WO2012060022A1 - Method for forming tin or solder coat film and device therefor - Google Patents

Method for forming tin or solder coat film and device therefor Download PDF

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Publication number
WO2012060022A1
WO2012060022A1 PCT/JP2010/073262 JP2010073262W WO2012060022A1 WO 2012060022 A1 WO2012060022 A1 WO 2012060022A1 JP 2010073262 W JP2010073262 W JP 2010073262W WO 2012060022 A1 WO2012060022 A1 WO 2012060022A1
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Prior art keywords
solder
tin
lead
pad
mass
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PCT/JP2010/073262
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French (fr)
Japanese (ja)
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石川　久雄
正徳 横山
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ホライゾン技術研究所株式会社
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Priority to JP2012541703A priority Critical patent/JPWO2012060022A1/en
Publication of WO2012060022A1 publication Critical patent/WO2012060022A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
    • H01L21/4853—Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • B23K35/262—Sn as the principal constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • B23K35/3601—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • B23K35/362—Selection of compositions of fluxes
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Definitions

  • the present invention relates to electronic components such as semiconductor elements, semiconductor chips, semiconductor wafers, interposers (wiring boards), lead frames, semiconductor devices, capacitors, capacitors, inductors, resistors, connectors, printed circuit boards, mounting boards, and electronic devices.
  • the present invention relates to a method and apparatus for forming a tin or solder film on pads or leads on an electronic circuit, and in particular, said electron comprising a fine electronic circuit in which a large number of pads or leads having a small area are arranged at a narrow pitch.
  • a smooth and uniform relatively thin tin or solder film is formed on all pads or leads of strips or strips (hereinafter referred to as electronic component assemblies) in which a large number of components or electronic components are arranged in a matrix.
  • the purpose of the present invention is to provide a technique useful for making it possible and a technique relating to the apparatus A.
  • the lead area is miniaturized, and the adjacent pitch is also becoming narrower.
  • the solder pre-coating area on the pads or leads necessary for joining the solder balls to form the bumps is becoming increasingly smaller.
  • there are many small electronic components such as ultra-mini transistors, ultra-mini diodes, and mini-capacitors that are assembled and formed as a multi-row lead frame strip that is arranged in a matrix.
  • the leads are also becoming increasingly narrow.
  • the pads or leads on the electronic circuit board on which these micro electronic components are mounted on the surface are naturally miniaturized and fine pitches are reduced accordingly, and these electronic components are well soldered.
  • an area for forming a tin or solder film necessary for facilitating soldering, or an area for applying a thin gold plating on a base plating of nickel has been increasingly miniaturized.
  • tin or solder film formation by the conventional methods (A) and (B) can be applied to a relatively wide pad or lead without any problem, when the pad or lead width becomes narrow, it is locally between adjacent pads or leads. In order to form a bridge, it is generally said that the minimum width is 0.15 mm and the pitch between adjacent pads or leads is 0.2 mm. In the case of an electronic circuit with a minute width and pitch smaller than this, In these methods, it is difficult to form a tin or solder film having no bridge.
  • (A) Molten tin or molten solder bath immersion method is the most widely used method since the oldest. Generally, the surface other than the pad or the lead is protected by the solder resist film, and only the pad or the lead portion is used. The exposed electronic circuit board is immersed in a flux solution, or flux is applied to the pad or lead surface, and then immersed in a molten tin or solder bath to utilize the reducing power of the flux. In this method, an oxide film on the pad surface is removed to improve solder wettability, and tin or a solder film is formed on the pad or lead. Generally, in this method, tin or solder adheres relatively thickly (several tens to 100 ⁇ m).
  • Patent Document 1 a hot liquid leveling method in which a molten solder is sprayed on an electronic circuit surface of 0.2 mm or less to form a solder film, and then a high-temperature liquid having a large specific gravity is sprayed to blow off excess solder.
  • Patent Document 1 a circuit width of 0.1 mm is a limit.
  • Patent Document 2 For the purpose of forming a solder precoat film, there has been proposed a hot air leveling method (Patent Document 2) in which, after forming a solder layer, high temperature air is blown onto the solder layer to blow off excess solder.
  • Patent Document 2 a hot air leveling method in which, after forming a solder layer, high temperature air is blown onto the solder layer to blow off excess solder.
  • a circuit width of 0.1 mm is a limit.
  • the variation range of the thickness of the solder precoat film that is finished by hot air leveling is usually about 10 ⁇ m, and there is a problem that the defective rate of electronic device assembly is high.
  • solder paste coating / fusion method has been widely used for a long time, and has been widely used even today, and the surface other than the pad or lead is protected with a solder resist film, and the pad or lead portion Reflow after the solder paste (cream solder) is applied to the pad or lead by screen printing etc. using a mask with an opening corresponding to the pad or lead position.
  • the solder paste of 20-80 ⁇ m ⁇ in the solder paste is melted and fused while improving solder wettability by removing the oxide film on the pad or lead surface using the reducing power of the flux present in the solder paste.
  • a solder film or a solder precoat film of 30 to 80 ⁇ m is formed.
  • solder paste application / fusion method the limit of the solder paste application accuracy by screen printing or the like (the limit for forming a solder coating) depends on the viscosity of the solder paste, the solder particle diameter, and the application conditions. It is said that the minimum width at which a solder film can be formed on a lead is at most 0.1 mm and the adjacent pitch is 0.15 mm. In particular, the pad or lead width is 0.02 to 0.08 mm, and the adjacent pitch is 0.04 to 0.12 mm. It is extremely difficult to stably form a solder film or a solder film having a good uniformity of 3 to 15 ⁇ m in thickness without bridging or missing in such a minute and fine electronic circuit.
  • the (C) tin or solder plating method and the (D) Ni / Au plating method are technologies that are particularly advantageous for pre-coating fine and fine circuits. Recently, they have been used for pre-coating micro-fine pads for semiconductor wafers and interposers. Has been applied.
  • the method (C) is a method in which an electronic circuit board in which the surface other than the pad or the lead is protected with a solder resist and only the pad or the lead part is exposed is desired in a plating solution containing a metal ion of a solder component.
  • a method of forming a solder film by plating to a thickness for example, a fine fine electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm and a thickness of 3 to 15 ⁇ m. It is possible to form a uniform solder precoat film. However, since aqueous solutions are mainly used, water molecules permeate into the electronic circuit board, requiring quality problems that reduce reliability, pre-treatment, water washing, post-treatment, etc. However, the process management is long and the cost is high.
  • Ni / Au plating in the (D) method is mainly to prevent internal diffusion of elements in the tin or solder components inside the electrode, as in the case of an aluminum evaporated electrode pad on silicon such as a wafer.
  • a thin gold plating is coated on the surface. Similar to the method C), for example, a uniform solder precoat film with a thickness of 3 to 15 ⁇ m is applied to a minute fine electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm. It is possible to form.
  • the procedure of the method (B) is further added on the gold plating to form a solder film, but in this case, the explanation of the method (B) is performed.
  • the minimum pad or lead width is 0.1 mm and the adjacent pitch is 0.15 mm.
  • the pad or lead width is 0.02 to 0.08 mm and the adjacent pitch is 0.04 to 0.12 mm. It is almost impossible to stably form a uniform solder film having a thickness of 3 to 15 ⁇ m on such a minute and fine electronic circuit without bridging or missing.
  • the ones in which the solder coating is formed by the hot air leveling method and the hot liquid leveling method are tin-copper solder alloys, tin-silver solder alloys, tin-silver-copper solder alloys that have been widely used as lead-free solder alloys in recent years.
  • tin-copper solder alloys tin-silver solder alloys
  • tin-silver-copper solder alloys that have been widely used as lead-free solder alloys in recent years.
  • IMC intermetallic crystals
  • the minimum width of an electronic circuit capable of forming a solder precoat film is the pad
  • the lead width is at most 0.1 mm
  • the adjacent circuit pitch is limited to 0.15 mm
  • the width less than that and the minute pitch solder joint electronic circuit formation of the adjacent bit can be formed by the electroplating method of (C) and (D).
  • the electroplating method of (C) and (D) it has not been fully put into practical use yet.
  • the pad width is 0.08 mm or less and adjacent A micro-fine circuit with a pitch of 0.12 mm or less is desired, but with the current method of forming a solder film, there is a high probability that a bridge will be formed even if the solder is locally attached, and most of the soldering does not occur (missing). Since it occurs frequently, it has become a bottleneck for further miniaturization, miniaturization, and weight reduction.
  • the present invention has a difficulty in the conventional method for forming a solder film on a pad or lead of an electronic component, that is, a fine fine narrow pitch high density electron having a pad or lead width of 0.08 mm or less and an adjacent pitch of 0.12 mm or less.
  • the present invention provides a technique for forming a uniform tin or solder film with high quality and reliability by solving the difficulty of forming tin or solder film on a circuit.
  • all the above-mentioned pads that have been cleaned of an electronic circuit board or an electronic component assembly in which surfaces other than the pads or leads are protected with a solder resist film and only the pads or leads are exposed.
  • a first step of mounting at least one tin or solder fine particle on the lead surface a second step of fusing the tin or solder fine particle to the pad or lead surface to form a tin or solder film;
  • a hot organic fatty acid solution onto the surface of the solder film to blow off and remove the excessively attached tin or solder, the pad or the lead has a thickness of 2 to 20 ⁇ m and a variation in thickness.
  • a uniform tin or solder film of ⁇ 3 ⁇ m or less is formed.
  • the pad or lead surface is sufficiently clean and has an anti-oxidation protective film (such as an OSP-treated imidazole film or an organic fatty acid chemically adsorbed protective film).
  • an anti-oxidation protective film such as an OSP-treated imidazole film or an organic fatty acid chemically adsorbed protective film.
  • the height difference (step) between the solder resist film and the opened pad or lead surface is usually 10
  • the height difference (step) between the solder resist film and the opened pad or lead surface is usually 10
  • ⁇ 30 ⁇ m there is a problem of the wetting angle due to the surface tension of the molten tin solution or molten solder solution, or on the pad or lead that is indented.
  • solder paste application / fusion method Due to the problem of air bubbles staying in the surface, molten tin or molten solder is very difficult to adhere to the pad or lead, and the solder paste is applied by screen printing in the conventional method (B) (solder paste application / fusion method). It is very difficult to completely (100%) fill all the very small pads or leads.
  • the pad or lead surface is not necessarily clean and oxidized
  • a flux in this case may be a normal solder flux, but a corrosive chlorine-containing flux is not preferred when quality reliability is important.
  • a flux containing nickel palmitate / or cobalt palmitate Japanese Patent No. 4389112
  • Kirkendall void that occurs over time at the tin or solder joint interface after high temperature exposure of electronic components and electronic devices.
  • the purpose of using the flux in this case is to remove residual oxide on the pad or lead surface, to adhere tin or solder fine particles to the flux, and to ensure that the adhered fine particles have good wettability. It is to be fused to the lead surface.
  • the flux on the surface of the pad or the lead may be applied with a brush, a roll or a squeegee, or the flux may be diluted with a solvent and sprayed with a spray. Further, all the pads and lead surfaces are indispensable for the place where the flux is interposed, but there is no particular problem even if the solder resist surface or the entire work surface is uniformly applied.
  • the tin or solder fine particles used in the first step of the present invention contain 1% by mass or more of fine particles having a particle diameter smaller than the width of the fine pad or lead exposed in the opening. If the particle diameter is too large, as described above, tin or solder particles do not enter the pad or lead opening surrounded by the high wall of the solder resist (generally 10 to 30 ⁇ m in thickness). This is because it becomes difficult to fuse tin or solder fine particles to the pad or lead surface in the second step of the present invention. Desirably, it is efficient to contain 10% or more of fine particles having a particle size of 1/2 or less of the exposed width (opening diameter) of the pad or lead.
  • the shape of the fine particles a spherical shape and a smooth surface are preferable because the rolling property and gas entrainment at the time of fusion are small. Further, it is desirable from the viewpoint of bonding reliability that the surface is not contaminated and further not oxidized.
  • the method of spraying tin or solder fine particles in the first step is, for example, for a work composed of a minute fine pitch high-density electronic circuit having a pad or lead width of 0.08 mm or less and an adjacent circuit pitch of 0.12 mm or less.
  • the work 1 may be sprayed from the top using a normal metal mask, may be applied using a squeegee as in screen printing, or may be applied using a brush.
  • the work 1 is vibrated as shown in FIG.
  • the tin or solder fine particles 4 may be sprayed and mounted from the nozzle 3 while scanning the powder spraying device 2 installed on the top.
  • the work 1 may be arranged with an inclination in the range of 5 to 60 degrees. If the surface of the pad or lead is not clean, the fine particles are dispersed in a diluted flux and sprayed, or a paste-like flux and the fine particles kneaded are applied to the pad or lead surface. Good.
  • solder As the material type of the tin or solder fine particles to be dispersed, normal solder widely used in electronic parts, that is, pure tin, tin-lead alloy, tin-silver-copper alloy, tin-zinc alloy, tin bismuth, etc. Further, a solder obtained by adding nickel, germanium, indium, antimony, phosphorus, or the like to these base alloys or these mother alloys may be used. However, lead-free solder is desirable from the viewpoint of environmental problems.
  • solder alloy added with 1% by mass and any one or more of 0.001 to 0.1% by mass of germanium or 0.003 to 0.05% by mass of phosphorus is used, a comparison of at most 140 to 180 ° C. It is possible to solder at low temperatures, and the effect of adding a small amount of nickel and germanium makes the surface of the formed solder film difficult to oxidize and a smooth solder film with no irregularities on the finished surface. There is also. In particular, when tin or solder added with a small amount of nickel is used, a nickel barrier layer is formed at the joint interface, and the copper of the pad or lead is effective in suppressing / preventing elution and diffusion in the molten solder solution. Is desirable.
  • the fine particles may be mounted not only on the pads or leads that are open on the workpiece but also on the solder resist portion around the pads, or in extreme cases, the fine particles may be excessively loaded on the entire surface of the workpiece. good. In these cases, naturally, when the fine particles are fused to the work pad or lead in the second step of the present invention, they are bridged with an adjacent circuit, or exist in the form of a ball on the solder resist.
  • the excess tin or solder is removed by the third step of the present invention, and there is no problem because a desired tin or solder film is formed only on the pad or lead portion.
  • the copper thickness of the pad or lead is very thin (for example, 5 ⁇ m or less)
  • the so-called “copper erosion” may cause copper to dissolve and diffuse in the molten solder, and the pad or lead may disappear.
  • the amount of tin or solder fine particles is too small, the desired tin or solder film thickness cannot be formed.
  • the fine particles are “nucleated” in the second step of the present invention.
  • the workpiece is fused to the pad or lead of the workpiece, the workpiece is immersed in a separately prepared molten tin bath or molten solder bath, or molten tin solution or molten solder solution is sprayed onto the workpiece pad or lead, and the pad Alternatively, a sufficient amount of tin or solder is placed on the fused tin or solder “core” of the lead portion.
  • the upper layer high-temperature organic fatty acid solution (for example, palmitic acid solution or the like) is passed, and the work 1 is immersed in the molten tin bath or the molten solder bath in the lower layer, or the molten tin solution or the molten solder solution and the high temperature
  • an organic fatty acid solution for example, palmitic acid solution, etc.
  • the circuit has a pad or lead width of 80 ⁇ m or more, it is not always necessary to spray tin or solder fine particles in the first step of the present invention. If necessary, another molten tin or molten solder solution can be used by using a flux. It is possible to form a tin or solder film on the pad or lead of the work simply by dipping directly in the bath.
  • a general oven heating furnace
  • a reflow furnace a flow furnace
  • an infrared or far infrared heater heating etc. It may be heated and fused in a heating atmosphere, or may be heated and fused on a hot plate.
  • a non-oxidizing liquid such as a high-temperature organic fatty acid solution (for example, palmitic acid solution) higher than the melting point of the tin or solder fine particles. It is extremely effective.
  • the temperature condition for the fusion is controlled to a temperature within the range of the melting point of the tin or solder fine particles +10 to 50 ° C., and the fusion is performed in as short a time as possible. At that time, by controlling the temperature of the entire work including the remaining heat to be as uniform as possible, and making the fusion time within 5 seconds, preferably 3 seconds or less, it is possible to avoid loss of pads or leads due to copper erosion. .
  • the organic fatty acid solution used in the third step of the present invention is caproic acid, caprylic acid, 2-ethylhexic acid, nonanoic acid, capric acid, undecanoic acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid
  • An organic fatty acid solution having a carboxyl group (—COOH) such as linolenic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, and melissic acid is preferable.
  • organic fatty acids which are preferably dissolved in a solvent used at 180 to 300 ° C.
  • organic fatty acids having a low boiling point it can be used at a high pressure, but it is not preferable in terms of safety and practicality.
  • organic fatty acids having 13 to 20 carbon atoms that is, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidin. Acid, arachidonic acid and the like, which are particularly useful because they have a great effect in accordance with the object of the present invention.
  • organic fatty acids can be used even with carbon atoms of 12 or less, they have water absorbency and are not very desirable due to their use at high temperatures, and even if they are coated as a protective film on the surface of tin or solder after excess solder is removed Therefore, the quality during long-term storage may be hindered, which is not always preferable. Further, although organic fatty acids having 21 or more carbon atoms can be used, the melting point is high and the rust preventive effect on the solder surface after treatment is slightly insufficient. Particularly desirable are industrially produced in large quantities in large quantities, used in various fields, and easily available, such as 16 carbon atoms of palmitic acid and 18 carbon atoms of stearic acid, and any one or more of them are used. The use of a solution having a liquid temperature of 180 to 300 ° C. composed of an oil-based solvent that is 1 to 80% by weight and the balance is stable in a high temperature region, also has a great effect of the present invention.
  • the purpose of using the organic fatty acid solution having a carboxyl group (—COOH) for the removal of surplus tin or solder in the third step of the present invention is as follows.
  • the effect of scavenging off is much greater than that of other organic compounds, and secondly, there is an effect of cleaning impurities and metal oxides in the fused tin or solder layer, and after removing excess tin or solder.
  • the organic fatty acid is chemisorbed on the surface of tin or solder remaining on the pad or lead to form an anti-oxidation protective film, and third, unnecessary dust and tin or solder fine particles adhering to the surface of the workpiece are washed away. This is because the effect is extremely large.
  • the effect of removing the first excess solder is a phenomenon newly discovered by the inventors as a result of trial and error of various organic compounds.
  • the concentration of the organic fatty acid in the organic fatty acid solution is effective even if it is 1% by mass or less, but replenishment management is complicated when processing a large amount continuously, and even if it is 80% by mass or more or 100% by mass alone Although the effect of the present invention is available and can be used, the problem of smoke generation and odor is also severe, so 5 to 80% by mass is preferable.
  • the liquid temperature of the organic fatty acid solution is an essential condition that is equal to or higher than the melting temperature of the tin or molten solder film formed in the second step, but the upper limit temperature is ignitable, fuming, and safe. In consideration of the problem of odor and energy saving, it is desirable to use an organic fatty acid solution at a liquid temperature 10 to 40 ° C.
  • the liquid temperature of the organic fatty acid solution used is 240 to 280. ° C is optimal.
  • the excess tin or solder removal efficiency in this case is not significantly different from the case where the liquid temperature of the organic fatty acid solution is increased from 280 ° C. to 320 ° C.
  • the temperature of the organic fatty acid solution used is sufficiently within the range of the melting point +10 to 40 ° C. is there. If it exceeds 280 ° C, there is a risk of ignition, so a nitrogen atmosphere is recommended.
  • the organic fatty acid solvent used in the present invention may be any of mineral oil, vegetable oil, and synthetic oil as long as it dissolves the organic fatty acid and is stable in the high temperature range. Ester synthetic oil is most suitable in terms of economy and handling.
  • the purpose and reason for using a solvent that is stable at high temperature is that the organic compound emits high-temperature smoke and suppresses odor, and also has good cleanability when washing off excessively attached organic fatty acid solution after soldering treatment. This is because the effect of lowering the liquid viscosity and improving the permeability is large.
  • the concentration is determined by the organic fatty acid concentration.
  • a work 1 is simply immersed vertically or inclined in the organic fatty acid solution 6 at a high temperature to give a physical vibration to the work (applying an inclined immersion vibration). Method). Even in this method, the tin or solder spheres existing on the bridge or solder resist generated in the second process, and unnecessary tin or solder such as unnecessary dust or tin or solder fine particles adhering to the surface of the workpiece are washed away. As a result, a good tin or solder film can be formed only on the pads or leads of the fine circuit of the workpiece.
  • the tilt angle of the workpiece is generally effective from 5 to 90 degrees, although it depends on the magnitude of physical vibration applied to the workpiece.
  • a desirable inclination angle is 30 to 90 degrees.
  • the thickness or shape of the tin or solder film remaining on the pad or lead surface is likely to vary, and it is particularly difficult to finish uniformly within ⁇ 2 ⁇ m within a thickness of 2 to 10 ⁇ m as in the case of a precoat film. .
  • a bridge may remain locally, and this inclined immersion method has a limit.
  • a method of spraying the organic fatty acid solution at a high temperature onto the workpiece (simple spraying method), or a method of spraying the organic fatty acid solution onto a workpiece immersed in the organic fatty acid solution at a high temperature (immersion spraying method)
  • immersion spraying method there is a method of scraping excess tin or solder with a roller or a squeegee in the liquid while immersing the workpiece in the high-temperature organic fatty acid solution.
  • the simple spraying method for example, as shown in FIG. 2, sprays a hot organic fatty acid solution from the nozzle 9 onto the work 1 and blows off the tin or solder excessively attached to the pad or the lead.
  • the immersion spraying method is a pump for transferring the hot organic fatty acid solution 6 in the liquid storage tank 5 in the upper part while pulling up the work 1 immersed in the hot organic fatty acid solution. 7 is supplied through the pipe 8 and sprayed with a high-temperature organic fatty acid solution 6 from the nozzle 9 at the tip to the work 1, thereby existing on the bridge 12 (FIG. 8) and the solder resist 10 generated in the second step.
  • the excess tin or solder ball or the unnecessary material 14 (FIG.
  • FIG. 4 the spraying of the organic fatty acid solution 6 is shown as an example in the air in the upper part of the liquid. However, the same effect can be obtained by performing the spraying process by installing the nozzle 9 in the organic fatty acid solution 6. Is obtained. Although there is a slight difference between the presence or absence of residual heat of the workpiece and the processing time, as a result, the simple spraying method and the immersion spraying method are effectively the same in the quality of tin or solder film formation.
  • the flow velocity sprayed from the nozzle 9 and the spraying treatment time vary depending on conditions such as a desired tin or solder film thickness, nozzle shape, spraying angle, etc.
  • the desired precoat film thickness is 5 ⁇ 2 ⁇ m
  • the tip of the nozzle is slit and the opening width is 0.5 to 3 mm and the opening length is 50 to 500 mm
  • the spray angle is 45 to 90 degrees with respect to the workpiece 1
  • a flow rate of 0.5 to 4 m / second and a substantial spraying treatment time of 0.5 to 5 seconds are sufficient.
  • the nozzle shape may be a commercially available nozzle for watering. In that case, a plurality of nozzles may be arranged so that the organic fatty acid solution to be sprayed uniformly against the width of the workpiece. Two or more nozzles may be scanned two-dimensionally or three-dimensionally.
  • the organic fatty acid solution 6 is put on the pad of the work 1 or the reverse roll 22 (rotated in the direction opposite to the pulling direction of the work 1) installed in the liquid of the high-temperature organic fatty acid solution 6.
  • the reverse roll diameter Is preferably in the range of 60 to 200 mm ⁇ and the rotation speed of 600 to 3000 rpm. The larger the roll diameter and the higher the rotation speed, the thinner the film thickness of the obtained tin or solder film.
  • tin or solder scraped off by the rotation of the reverse roll 22 may be dispersed in the organic fatty acid solution and reattached to the treated upper pad or lead portion.
  • a baffle 23 may be installed on the upper portion of the reverse roll 22.
  • the gap between the work 1 and the reverse roll 22 may be about 0, 1 to 5 mm.
  • the conventional method (A) Molten solder bath immersion method can be used by simply immersing in a high-temperature organic fatty acid solution as described above. Even in the circuit pattern bridging in, when passing through the organic fatty acid solution, the bridge is eliminated by the action of the organic fatty acid, there is no need for the high-temperature organic fatty acid solution spraying leveler treatment of the third step of the present invention, of course, There is no need for conventional hot air leveler processing or hot liquid leveler processing. The inventors have found that high-temperature organic fatty acids exhibit a specific separation effect for excess molten tin or molten solder.
  • the conventional hot air leveler process or hot liquid leveler process is performed, or the third step of the present invention is performed.
  • the variation of the precoat film thickness obtained by the hot air leveler treatment or the hot liquid leveler treatment of the conventional method is very large, whereas in the method of the present invention, the thickness variation is far larger. It was verified that a small and uniform precoat film was obtained, and that the effect of leveling treatment with an organic fatty acid solution was extremely large.
  • the solder precoat film formed by the conventional hot air leveling method and hot liquid leveling method is a tin-copper solder alloy, a tin-silver solder alloy, a tin-silver solder that has been widely used as a lead-free solder alloy in recent years.
  • a tin-copper solder alloy a tin-silver solder alloy
  • a tin-silver solder that has been widely used as a lead-free solder alloy in recent years.
  • IMC intermetallic crystals
  • the surface of the solder precoat film after leveling with a solder precoat thickness of 10 ⁇ m or less becomes uneven, and there is also a drawback that the solder thickness varies greatly.
  • solder precoat film contains a trace amount of nickel of 0.005 to 0.5 mass%, and a trace amount of germanium of 0.001 to 0.1 mass% or phosphorus of 0.003 to 0.1 mass%
  • a solder precoat film is formed by the method of the present invention using a solder alloy containing tin and the balance tin, it has been found that a precoat film with good smoothness can be obtained.
  • eutectic solder such as tin-lead alloy (tin 63 mass%, lead 37 mass%), tin bismuth alloy (tin 42 mass%, bismuth 58 mass%), tin antimony alloy, etc. If a solder added with 0.005 to 0.5 mass% and one or more of 0.001 to 0.1 mass% of germanium or 0.003 to 0.1 mass% of phosphorus is used, the solder Even when the thickness of the precoat film is 20 ⁇ m or less, the glossy surface is almost completely smooth. Further, there is an advantage that no whisker is found in the tin plating precoat.
  • a tin bismuth eutectic alloy which is a low temperature solder (for example, a semiconductor device)
  • a tin bismuth eutectic alloy which is a low temperature solder (for example, a semiconductor device)
  • ordinary lead-free solder eg tin-silver-copper solder, tin-copper solder, tin-silver solder, etc.
  • the tin bismuth solder precoat film melts at a low temperature of about 140 to 180 ° C., the bonding temperature with the normal lead-free solder is slightly lower and the bonding time is shorter than that of the conventional method. There is a merit of less thermal damage.
  • the reason for adding a small amount of nickel to tin is to suppress so-called "copper erosion” (a phenomenon in which copper on the pad or lead surface melts into the solder) when tin or solder is coated on the pad or lead surface of the electronic circuit.
  • it suppresses the Kirkendall voids (microvoids) that occur near the solder joint interface when exposed to a high temperature cumulatively over 120 ° C over a long period of time. This is to improve the quality reliability of the product.
  • the amount is 0.001% by mass or less, the effect is small, and when the amount is 1% by mass or more, the viscosity at the time of melting becomes high and bridging is likely to occur.
  • a desirable addition amount of nickel is 0.005 to 0.5 mass%. Addition of cobalt or iron instead of nickel is effective.
  • the reason for adding germanium or phosphorus is mainly to prevent the oxidation of the solder precoat film surface over time and the deterioration of solder wettability. In the case where this is not added, if the solder pre-coated product is left in the air, it will undergo oxidative discoloration over time and solder wettability will deteriorate. If the added amount is small, the effect is small, and if it is too large, the physical mechanical properties become brittle and it is easy to break. Therefore, a desirable addition amount is 0.001 to 0.1% by mass of germanium or 0.003 to 0.1% by mass of phosphorus.
  • the amount of tin or solder fine particles dispersed in the first step is rather small, and at least one tin or solder fine particle is mounted on at least all the pads or leads of the workpiece, After the fine particles are fused to the work pad or lead in the second step, a high temperature organic fatty acid solution and a molten tin solution or a molten solder solution are sprayed to the work with a dedicated pump as the third step. It is efficient that a tin or solder joint film is formed on the surface of the pad or the lead. Specifically, as shown in FIG. 6, while the workpiece 1 is running as shown in FIG.
  • the transfer pump 7 sprays the high-temperature organic fatty acid solution 6 from the nozzle 9 onto the pad or lead surface of the workpiece 1, and at the same time, the transfer pump 16.
  • the tin or solder solution 15 By spraying the molten tin solution or the molten solder solution 15 from the nozzle 17, the tin or solder fine particles fused in the second step are used as a core to supplement the missing tin or solder amount.
  • the spraying of the high-temperature organic fatty acid solution 6 and the spraying of the molten tin solution or the molten solder solution 15 bring the nozzles 9 and 17 close to each other so that both solutions overlap.
  • the nozzles 17 may be sprayed, or the nozzles 9 may be slightly spaced from each other around the nozzle 17 (at least 20 mm) and sprayed.
  • the cross-sectional shape of the ejection part of the nozzle but considering productivity, an elliptical shape or a slit shape in which the direction perpendicular to the traveling direction of the workpiece is long is efficient and desirable. If the electronic circuit board, the electronic component connector, the semiconductor lead frame, or the like is a long strip, the method of the present invention can be performed while being conveyed by continuous feeding or intermittent feeding.
  • a high-temperature organic fatty acid solution is sprayed on the surface of the workpiece to remove the tin or solder adhered excessively, and the pad or lead has a thickness of 2 to 20 ⁇ m.
  • a “bridge” can be formed by the conventional method, a pad or lead width of 20 to 80 ⁇ m and a fine narrow pitch high density electronic circuit having an adjacent pitch of 40 to 100 ⁇ m cannot be formed. There is a remarkable effect that industrially stable mass production of tin or solder coating is possible while controlling the thickness variation within a range of 2 to 20 ⁇ m and relatively freely within ⁇ 3 ⁇ m.
  • the high-density electronic device mounted and mounted by soldering using an electronic circuit board and an electronic component having a tin or solder coating manufactured by the method of the present invention is fused to the pad or lead in the second step of the present invention.
  • the tin or solder layer is sprayed with a high-temperature organic fatty acid solution in the third step so that the tin or solder layer is melted again, and microbubbles or voids, metal oxides, flux existing in the layer. While removing reaction products and other impurities and removing excess tin or solder, the required amount of tin or solder layer is firmly bonded to the pad or lead surface, so there is no finally formed tin or solder layer. In addition, in the bonding interface, microbubbles and voids in the bonding interface and in the solder layer and in the bonding interface due to the boiling-off of the flux often seen in the conventional methods (A) and (B). Not at all.
  • a chemical adsorption protective film (antioxidation film) of organic fatty acid is inevitably formed on the surface of the finished tin or solder film, so that it is oxidized even after storage in the atmosphere for a long time. Difficult to discolor and maintains good solder wettability. Therefore, the solder wettability at the time of assembling the electronic device in the subsequent processes is stable and superior to those manufactured by the conventional method.
  • the tin or solder precoat film is 5 ⁇ m or less, the intermetallic compound (IMC) is exposed on the surface, and if the surface is oxidized after long-term storage, soldering cannot be performed thereon, but the film thickness processed by the method of the present invention is 5 ⁇ m.
  • the film thickness processed by the method of the present invention is 5 ⁇ m.
  • IMC intermetallic compound
  • even if IMC is exposed on the surface it can be sufficiently soldered even after long-term storage in the air. This is considered to be an effect that an organic fatty acid chemical adsorption protective film (antioxidant coating film) is formed on the surface of the precoat film.
  • an organic fatty acid chemical adsorption protective film antioxidant coating film
  • FIG. 4 is a cross-sectional view schematically showing a state in which a solder film is formed on the surface of a pad or lead by pulling up while applying and removing excess tin or solder.
  • the immersion spraying method which is one of the third step embodiments of the method of the present invention, the high temperature organic fatty acid solution is sprayed by the upper nozzle while pulling up the work previously immersed in the high temperature organic fatty acid solution tank.
  • FIG. 6 is a cross-sectional view schematically showing a state in which excess tin or solder is removed to form a solder film on the pad or lead surface.
  • the immersion roll spraying method which is one of the embodiments of the third step of the method of the present invention, a work previously immersed in a high-temperature organic fatty acid solution tank is placed between two reverse rolls installed in the liquid. The organic fatty acid solution is sprayed onto the pad or lead part of the work by high-speed rotation of the reverse roll while passing the wire up and removing the excess tin or solder to form a solder film on the pad or lead surface. It is sectional drawing shown typically.
  • a high-temperature organic fatty acid solution is used as the upper layer, and a molten tin solution or molten as the lower layer.
  • Each liquid is supplied to the nozzle from the storage tank in which the solder liquid is arranged with a dedicated pump, and each liquid is sprayed from the nozzle onto the electronic circuit board or electronic component assembly (workpiece), so that excess tin or solder It is sectional drawing which showed typically a mode that a solder
  • FIG. 1 is a cross-sectional view schematically showing a state where the powder is sprayed from a powder spraying device to a workpiece as a powder spraying example made of tin or solder fine particles, which is one of the first step embodiments of the present invention. is there.
  • Sectional drawing which showed typically the cross-sectional state of the workpiece
  • FIG. 4 is a cross-sectional view after heat aging (150 ° C., 240 hours) of the solder precoat film produced in the examples of the present invention and the comparative example, and a) schematically shows the state of the precoat film of Comparative Example 2; ) Is a cross-sectional photographic example of a part of the precoat film of Comparative Example 2, similarly c) is a diagram schematically showing the state of the precoat film of Example 7, and d) is a cross section of a part of the precoat film of Example 7. This is an example of a photograph
  • Sample 1 A test circuit using 50 leads drawn as a unit with a lead width of 20 ⁇ m, a lead length of 6 mm, and an adjacent pitch of 50 ⁇ m centered on the center of the outer dimensions of 10 mm ⁇ 10 mm ⁇ 0.8 mm is 2 at 20 mm pitch.
  • an electronic circuit board in which test circuits each having 50 leads drawn in a unit of 50 rows drawn with a lead width of 40 ⁇ m, a lead length of 6 mm, and an adjacent pitch of 60 ⁇ m are arranged in two rows of X4 units at a pitch of 20 mm.
  • solder resist is applied to the entire work surface other than the lead portion, and the step difference between the solder resist film and the REIT surface is higher in the approximately 10 ⁇ solder resist film.
  • Sample 2 BGA with outer dimensions of 10 mm ⁇ 10 mm ⁇ 1.0 mm, number of electrode pads 304, pad diameter of 0.1 mm ⁇ , pad diameter of 0.08 mm ⁇ not covered with solder resist protective film, and pad pitch of 0.15 mm is 20 mm pitch Electronic circuit boards arranged in two rows of 4 each. As in the case of Sample 1, the step difference between the solder resist film and the REIT surface is higher in the approximately 10 ⁇ solder resist film.
  • a method for producing a low-oxygen solder alloy with a reduced oxygen concentration in the solder is 2.5% by mass of silver, 5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, and lead consisting of the balance tin.
  • a molten solder solution obtained by pre-melting a free solder alloy and an organic fatty acid solution having a liquid temperature of 260 ° C. composed of 30% by weight of palmitic acid and the remaining ester are circulated in a stirrer and vigorously stirred to melt the solder.
  • Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 10 ppm of oxygen, and the balance tin. After immersing Samples 1 and 2 in which the rosin flux was previously applied to the pad part for 2 seconds in the molten solder bath at 0 ° C. for 2 seconds and soldering to the pad part, the temperature was measured with a normal hot air leveler. It processed at 350 degreeC and the pressure (pressure gauge gauge) 0.2MPa.
  • Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin. After immersing Samples 1 and 2 in which the rosin flux was previously applied to the pad part for 2 seconds in the molten solder bath at 0 ° C. for 2 seconds and soldering to the pad part, the temperature was measured with a normal hot air leveler. It processed at 350 degreeC and the pressure (pressure gauge gauge) 0.2MPa.
  • Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin. After immersing samples 1 and 2 in which the rosin flux was previously applied to the pad portion for 2 seconds in the molten solder bath at 0 ° C. and soldering the pad portion, glycerin at a liquid temperature of 230 ° C. was added. The hot liquid leveler process which sprays and blows off the excess solder was performed.
  • Samples 1 and 2 were preliminarily immersed in a solution consisting of 10% by weight palmitic acid at a liquid temperature of 120 ° C. and the remaining ester synthetic oil to clean the surfaces of the pads and leads and to protect palmitic acid on the cleaned surfaces.
  • the above-mentioned pad is sprayed from above with solder fine particles composed of 2.5% by mass of silver having a particle diameter of 1 to 20 ⁇ m ⁇ , 0.5% by mass of copper, and the remaining tin with a powder spraying device as shown in FIG. A sufficient amount of the solder fine particles was mounted on the lead surface. At this time, the amount of the powder sprayed was about 30 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads.
  • the hot palmitic acid solution was sprayed at a flow rate of 2.0 m / sec while immersing the workpiece in a palmitic acid solution having the above composition at a liquid temperature of 260 ° C. in such an immersion spraying apparatus, and the pad and Excess solder was blown off and removed so that the finished thickness of the lead solder film was 5 ⁇ m.
  • Solder fine particles composed of 2.5% by mass of silver having a particle diameter of 1 to 10 ⁇ m, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, and the balance of tin with a powder spreader as shown in FIG. A sufficient amount of the solder fine particles were mounted on the pad and lead surfaces by spraying from above. At this time, the amount of the solder fine particles sprayed was about 50 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (workpiece) is carried into a reflow furnace having a maximum real temperature of 260 ° C. on the temperature profile and passed through the furnace to melt the solder fine particles mounted on the work, so that the pads and leads
  • a palmitic acid solution consisting of 10% by mass of palmitic acid at a liquid temperature of 260 ° C. in the immersion spraying apparatus as shown in FIG.
  • the hot palmitic acid solution was sprayed at a flow rate of 1.1 m / sec, and excess solder was blown off and removed so that the finished thickness of the solder film on the pads and leads was 10 ⁇ m.
  • a flux dilution solution consisting of 9% by weight of nickel stearate, 45% by weight of ordinary rosin flux, and the remaining solvent was applied to the surfaces of the pads and leads with a roller and dried, as shown in FIG.
  • Solder powder consisting of 2.5% by mass of silver having a particle diameter of 1 to 10 ⁇ m, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin with a simple powder spraying device A sufficient amount of the solder fine particles were mounted on the pad and lead surfaces by spraying from above.
  • the amount of the solder fine particles sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads.
  • a sufficient amount is obtained by immersing the workpiece in a solder bath composed of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the remainder of tin. After the solder and the solder are fused and stacked on the solder layer, a solution of 15 mass% stearic acid at a liquid temperature of 250 ° C.
  • ester synthetic oil is flowed from the nozzle of the apparatus as shown in FIG.
  • excess solder was blown off and removed so that the finished thickness of the solder film on the pads and leads was 5 ⁇ m.
  • the amount of the solder fine particles sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads.
  • the workpiece is immersed in a molten solder bath composed of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 1 ppm of oxygen, and the balance of tin.
  • a solution of 10 mass% stearic acid at a liquid temperature of 250 ° C. and the remaining ester synthetic oil is flowed from the nozzle of the apparatus as shown in FIG. The excess solder was blown off and removed so that the final thickness of the solder film of the pads and leads was 5 ⁇ m.
  • Samples 1 and 2 were sprayed with 5% by mass of nickel palmitate, 45% by mass of normal rosin-based flux, and the remainder of the solvent by spraying on the surfaces of the pads and leads, and dried.
  • a powder spraying device such as No. 1, 01% by weight of nickel with a particle size of 1 to 15 ⁇ m ⁇ , 0.005% by weight of germanium, oxygen concentration of 2 ppm, the remaining solder tin consisting of tin is sprayed from the top, and it is sufficient on the pad and lead surface
  • An appropriate amount of the solder fine particles was mounted. At this time, the amount of the solder fine particles sprayed was about 60 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads.
  • a solution consisting of 10% by mass of palmitic acid having a liquid temperature of 250 ° C. and the remaining ester synthetic oil is sprayed at a flow rate of 1.8 m / sec from a nozzle of such an apparatus, and the finished thickness of the solder film of the pads and leads becomes 6 ⁇ m.
  • excess solder was blown off and removed.
  • Samples 1 and 2 were sprayed with 5% by mass of nickel palmitate, 45% by mass of normal rosin-based flux, and the remainder of the solvent by spraying on the surfaces of the pads and leads, and dried.
  • 1 to 10 ⁇ m ⁇ tin 42 mass%, bismuth 58 mass%, oxygen concentration 3ppm tin tin bismuth eutectic alloy 0.07 mass% nickel, 0.005 mass% germanium
  • the added solder fine particles were dispersed from above and the solder fine particles were mounted on the pad and lead surfaces. At this time, the amount of the powder sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
  • each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads.
  • a solution consisting of 10% by mass of palmitic acid having a liquid temperature of 260 ° C. and the remaining ester synthetic oil was sprayed at a flow rate of 0.8 m / second, and then 42% by mass of tin and 58% by mass of bismuth from the nozzle 17.
  • molten solder added with 0.07% by mass of nickel and 0.005% by mass of germanium is sprayed onto a tin-bismuth eutectic alloy having an oxygen concentration of 3 ppm, and the liquid temperature is again returned by another nozzle 9 installed behind the molten solder.
  • a solution composed of 10% by mass of palmitic acid at 260 ° C. and the remaining ester synthetic oil was sprayed at a flow rate of 1.8 m / sec, so that the finished thickness of the solder film on the pads and leads was 6 ⁇ m. To form a solder film.
  • Each sample 2 of Examples 1 to 7 was mounted and soldered in a reflow furnace, and subjected to an evaluation test as an evaluation sample. In Comparative Examples 1 to 6, evaluation was not possible due to excessive missing.
  • the evaluation method for the presence or absence of voids in the vicinity of the solder joint interface is that the sample for the evaluation test is in a normal state and left in a constant temperature heating furnace at 150 ° C. for 240 hours, and after the heating aging acceleration test, the solder joint cross section is polished, Using a scanning electron microscope (SEM) and an X-ray microanalyzer (EPMA), the number and size of microvoids near the solder joint were observed, analyzed, and compared.
  • SEM scanning electron microscope
  • EPMA X-ray microanalyzer
  • the evaluation test sample was used as a normal state and a constant-temperature heating furnace. After the heat aging acceleration test after standing at 150 ° C. for 240 hours, the cross section of the solder joint is polished, and the micro void near the solder joint is observed by a scanning electron microscope (SEM) and an X-ray microanalyzer (EPMA). The number and size of these were observed, analyzed and compared.
  • SEM scanning electron microscope
  • EPMA X-ray microanalyzer
  • the present invention is a problem of the conventional method and similar prior art, such as a bridge problem when forming a solder precoat film of a fine circuit, a so-called micro-layer in a joint interface or a solder layer because it contains a flux component. It avoids the phenomenon of voids (small bubbles and voids), solves the problem of connection reliability over time, the problem of corrosiveness, and the problem of Kirkendall voids that occur over time after long-term high temperature exposure.
  • a tin or solder precoat film with a thickness variation of within ⁇ 3 ⁇ in a thickness range of 3-20 ⁇ m on a fine narrow-pitch electronic circuit with a lead width of 0.02-0.08mm and an adjacent pitch of 0.04-0.12mm Is a technological technology that has a very high industrial value.
  • Powder disperser screen made of fine mesh wire mesh from above, funnel container with top narrower and narrower toward the bottom, or commercially available powder disperser or container with spray spray nozzle at tip
  • Powder spraying device nozzle 4 Tin or solder fine particle 5
  • High temperature organic fatty acid solution storage tank 6
  • High temperature organic fatty acid solution 7
  • High temperature organic fatty acid solution transfer pump 8
  • High temperature organic fatty acid solution transfer pipe 9
  • Solder bridge 13 Excess tin or solder ball, unnecessary material such as dust adhering to the solder resist
  • Tin or solder film 15 Molten tin or solder liquid
  • Molten tin or molten Solder solution transfer pump 17

Abstract

A method for forming a tin or solder coat film on a small electrode pad or on a lead surface with a narrow pitch on an electronic circuit substrate or in an electronic component, the method including: a first step of placing tin or solder particles on a cleaned pad or a cleaned lead surface that is exposed on the electronic circuit substrate or an electronic component assembly (hereinafter referred to as "workpiece"), wherein the surface except the pad or the lead is covered by a solder resist film; a second step of fusing, as cores, the tin or solder particles on the pad or the lead surface to form the tin or solder coat film; and a third step of spraying high-temperature organic fatty acid solution on a surface of the tin or solder coat film to blow away the excessively attached tin or solder. Consequently, a uniform tin or solder coat film having the thickness of 2 to 20 µm with the thickness variation being ± 3 µm or less is formed on the pad or the lead.

Description

錫またははんだ皮膜の形成方法及びその装置Method for forming tin or solder film and apparatus therefor
　本発明は、半導体素子、半導体チップ、半導体ウエハー、インターポーザー（配線基板）、リードフレーム、半導体装置、コンデンサー、キャパシタ、インダクタ、抵抗器、コネクタ、プリント回路板、実装基板、電子装置などの電子部品の電子回路上のパッドまたはリードに錫またははんだ皮膜を形成させる方法及びその装置に関する技術であって、特に、微小面積のパッドまたはリードが狭ピッチで多数個配置された微細電子回路からなる前記電子部品または前記電子部品をマトリックス状に多数個配列した条帯または短冊板（以下、これを電子部品連結体という）の全てのパッドまたはリードに、平滑で均一な比較的薄い錫またははんだ皮膜を形成させることに有用な方法及びその装置に関する技術を提供することを目的としたものである。 The present invention relates to electronic components such as semiconductor elements, semiconductor chips, semiconductor wafers, interposers (wiring boards), lead frames, semiconductor devices, capacitors, capacitors, inductors, resistors, connectors, printed circuit boards, mounting boards, and electronic devices. The present invention relates to a method and apparatus for forming a tin or solder film on pads or leads on an electronic circuit, and in particular, said electron comprising a fine electronic circuit in which a large number of pads or leads having a small area are arranged at a narrow pitch. A smooth and uniform relatively thin tin or solder film is formed on all pads or leads of strips or strips (hereinafter referred to as electronic component assemblies) in which a large number of components or electronic components are arranged in a matrix. The purpose of the present invention is to provide a technique useful for making it possible and a technique relating to the apparatus A.
　近年、電子機器はますます高集積高密度小型軽量化され、品質的に高信頼性が要求されている。これに相応して、半導体チップ、ウエハー、インターポーザー、リードフレーム、半導体装置、抵抗器、コンデンサー、コネクタなどの電子部品はますます高密度小型化され、それらの電子回路上のパッドまたはリードは幅も隣接ピッチも微小狭小化が進んでいる。それに伴い、これらの電子部品を実装搭載する電子回路基板のパッドまたはリードもそれに対応してますます微小狭小化されてきている。
　例えば、電子部品の中でも、特に半導体装置のＢＧＡ（Ｂａｌｌ　Ｇｒｉｄ　Ａｒｒａｙ）、ＣＳＰ（Ｃｈｉｐ　Ｓｉｚｅ　Ｐａｃｋａｇｅ）の半導体チップやインターポーザー（配線基板）は、小型微小化に伴い、マトリックス状に配列された電極パッドまたはリードの面積は微小化され、隣接ピッチも微小狭ピッチ化が進んでいる。
　このため、はんだボールを接合してバンプを形成させるために必要なパッドまたはリード上のはんだプリコート面積もますます微小狭小化されてきている。このほか、超ミニトランジスタ、超ミニダイオード、ミニコンデンサなどの微小な電子部品は多列多数個取りでマトリックス状に配列されたリードフレーム条帯として組立て成形されているものも多く、その電極パッドやリードも同様にますます微小狭小化している。
　一方、これらの微小な電子部品を搭載して表面実装する電子回路基板側のパッドまたはリードも、当然、それに対応して微小化と微小狭ピッチ化が進み、これらの電子部品と良好なはんだ接合を容易にするために必要な錫またははんだ被膜を形成させる面積、あるいはニッケルを下地めっきした上に薄い金めっきを施す面積もますます微小化されてきている。 In recent years, electronic devices are increasingly highly integrated, high density, small and light, and high quality is required for reliability. Correspondingly, electronic components such as semiconductor chips, wafers, interposers, lead frames, semiconductor devices, resistors, capacitors, connectors, etc. are becoming increasingly dense and compact, and pads or leads on these electronic circuits are wide. The adjacent pitch is also becoming increasingly narrow. Along with this, the pads or leads of electronic circuit boards on which these electronic components are mounted and mounted have been correspondingly reduced in size.
For example, among electronic components, in particular, semiconductor devices such as BGA (Ball Grid Array) and CSP (Chip Size Package) semiconductor chips and interposers (wiring substrates) of semiconductor devices are electrode pads arranged in a matrix with miniaturization. Alternatively, the lead area is miniaturized, and the adjacent pitch is also becoming narrower.
For this reason, the solder pre-coating area on the pads or leads necessary for joining the solder balls to form the bumps is becoming increasingly smaller. In addition, there are many small electronic components such as ultra-mini transistors, ultra-mini diodes, and mini-capacitors that are assembled and formed as a multi-row lead frame strip that is arranged in a matrix. The leads are also becoming increasingly narrow.
On the other hand, the pads or leads on the electronic circuit board on which these micro electronic components are mounted on the surface are naturally miniaturized and fine pitches are reduced accordingly, and these electronic components are well soldered. In addition, an area for forming a tin or solder film necessary for facilitating soldering, or an area for applying a thin gold plating on a base plating of nickel has been increasingly miniaturized.
　一般に、電子回路基板のパッドまたはリードに錫またははんだ皮膜を形成する方法としては、（Ａ）溶融錫または溶融はんだ浴浸漬処理方式、（Ｂ）ソルダーペスト塗布・溶融方式、（Ｃ）錫またははんだめっき方式、（Ｄ）Ｎｉ／Ａｕめっき方式などが広く普及している。
　しかしながら、従来方法（Ａ）と（Ｂ）による錫またははんだ被膜形成は比較的広幅のパッドまたはリードには問題なく適用できるが、パッドまたはリード幅が狭くなると、局部的に隣接パッドまたはリード間にブリッジを生ずるため、一般的には最小幅は０．１５ｍｍ、隣接パッドまたはリード間ピッチは０．２ｍｍが限界と言われており、これ以下の微小狭小幅・ピッチの電子回路の場合には、これらの方法ではブリッジが全くない錫またははんだ皮膜を形成させることは困難である。 In general, as a method of forming tin or a solder film on a pad or lead of an electronic circuit board, (A) molten tin or molten solder bath immersion method, (B) solder paste coating / melting method, (C) tin or solder Plating methods, (D) Ni / Au plating methods, etc. are widely used.
However, although the tin or solder film formation by the conventional methods (A) and (B) can be applied to a relatively wide pad or lead without any problem, when the pad or lead width becomes narrow, it is locally between adjacent pads or leads. In order to form a bridge, it is generally said that the minimum width is 0.15 mm and the pitch between adjacent pads or leads is 0.2 mm. In the case of an electronic circuit with a minute width and pitch smaller than this, In these methods, it is difficult to form a tin or solder film having no bridge.
　即ち、（Ａ）溶融錫または溶融はんだ浴浸漬処理方式は、最も古くから実用普及している方法であり、一般に、パッドまたはリード以外の表面がソルダーレジスト膜で保護され、パッドまたはリード部のみが露出している電子回路基板を、フラックス液中に浸漬処理するか、もしくはパッドまたはリード表面にフラックスを塗布した後に、溶融した錫またははんだ浴の中に浸漬して、フラックスの還元力を利用してパッド表面の酸化膜を除去して、はんだぬれ性を改善しながら、パッドまたはリードに錫またははんだ皮膜を形成する方法である。
　この方法では、一般に、錫またははんだが比較的厚く付着（数１０~１００μｍ）するため、狭ピッチ回路やスルーホールを有する電子回路基板では局部的に隣接パッドまたはリード間でブリッジを生じ易く、微小なスルーホール内部にははんだ付着しにくい難点がある。
　従って、特に、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小微細電子回路の場合には、溶融錫またははんだ固有のぬれ角が小さいために、はんだレジスト膜の高い壁で囲まれた内底部の微小パッドまたはリード表面に、溶融はんだが殆ど接触接合できないため、錫またははんだ皮膜を形成することすら殆ど不可能な欠点がある。 That is, (A) Molten tin or molten solder bath immersion method is the most widely used method since the oldest. Generally, the surface other than the pad or the lead is protected by the solder resist film, and only the pad or the lead portion is used. The exposed electronic circuit board is immersed in a flux solution, or flux is applied to the pad or lead surface, and then immersed in a molten tin or solder bath to utilize the reducing power of the flux. In this method, an oxide film on the pad surface is removed to improve solder wettability, and tin or a solder film is formed on the pad or lead.
Generally, in this method, tin or solder adheres relatively thickly (several tens to 100 μm). Therefore, in an electronic circuit board having a narrow pitch circuit or a through hole, a bridge is easily generated locally between adjacent pads or leads. There is a difficulty in soldering in the through hole.
Therefore, especially in the case of a micro-fine electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm, the wet angle inherent to molten tin or solder is small. There is a drawback that it is almost impossible to form a tin or solder film because the molten solder cannot be contact-bonded to the inner bottom micropad or lead surface surrounded by the high wall of the solder resist film.
　このため、０．２ｍｍ以下の電子回路表面に溶融はんだを吹付けてはんだ皮膜を形成させた後、比重の大きい高温の液体を吹き付けて余剰のはんだを吹き落とすホットリキッドレベリング方法（特許文献１）が提案されている。
　しかしながら、この方法でも回路幅０．１ｍｍが限界であり、例えば前記パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小狭小電子回路の場合には、溶融はんだ固有のぬれ角が小さいために、ソルダーレジスト膜の高い壁で囲まれた内底部の微小パッドまたはリード表面に、溶融はんだが殆ど接触接合できないため、はんだ不着（以下、ミッシングという）なく全ての微小パッドまたはリード表面に安定して均一なはんだ皮膜またはプリコート皮膜を形成することは非常に困難である。 For this reason, a hot liquid leveling method in which a molten solder is sprayed on an electronic circuit surface of 0.2 mm or less to form a solder film, and then a high-temperature liquid having a large specific gravity is sprayed to blow off excess solder (Patent Document 1). Has been proposed.
However, even in this method, a circuit width of 0.1 mm is a limit. For example, in the case of a small and narrow electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm, Because the wet angle inherent to molten solder is small, almost no molten solder can contact and bond to the inner bottom micropad or lead surface surrounded by the high wall of the solder resist film, so there is no solder adhesion (hereinafter referred to as missing). It is very difficult to form a stable and uniform solder film or precoat film on the surface of the micropad or lead.
　また、はんだプリコート皮膜形成を目的とする場合には、はんだ層形成後、前記はんだ層に高温のエアーを吹き付けて余剰のはんだを吹き落とすホットエアーレベリング方法（特許文献２）が提案されている。
　しかしながら、この方法でも回路幅０．１ｍｍが限界であり、例えば前記パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小狭小電子回路の場合には、部分的にはんだ皮膜が形成されることはあっても、１つのミッシングもなく全ての微小パッドまたはリード表面に完璧に安定して均一なはんだ被膜を形成することは殆ど不可能である。また、部分的に形成されたはんだ皮膜においてもホットエアーレベリングでは仕上がるはんだプリコート皮膜厚さのばらつきの幅は通常１０μｍ程度あり、電子装置組立の不良率が高い難点がある。 For the purpose of forming a solder precoat film, there has been proposed a hot air leveling method (Patent Document 2) in which, after forming a solder layer, high temperature air is blown onto the solder layer to blow off excess solder.
However, even in this method, a circuit width of 0.1 mm is a limit. For example, in the case of a small and narrow electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm, Even if a solder film is partially formed, it is almost impossible to form a completely stable and uniform solder film on all the micropads or lead surfaces without one missing. Further, even in a partially formed solder film, the variation range of the thickness of the solder precoat film that is finished by hot air leveling is usually about 10 μm, and there is a problem that the defective rate of electronic device assembly is high.
　また、（Ｂ）ソルダーペースト塗布・融着方式も、かなり古くから広く普及し、現在でも広範囲に実用されている方法で、パッドまたはリード以外の表面がソルダーレジスト膜で保護され、パッドまたはリード部のみが露出している電子回路基板を、パッドまたはリード位置に相当する部分が開口しているマスクを利用して、スクリーン印刷等でソルダーペースト（クリームはんだ）をパッドまたはリードに塗布した後、リフロー処理をしてソルダーペースト中に存在するフラックスの還元力を利用してパッドまたはリード表面の酸化膜を除去してはんだぬれ性を改善しながら、ソルダーペースト中の２０~８０μｍφのはんだ粒子を溶融融合して３０~８０μｍのはんだ被膜またははんだプリコート皮膜を形成させている。（特許文献３、４、５）
　しかしながら、このソルダーペースト塗布・融着方法では、スクリーン印刷等によるソルダーペースト塗布精度の限界（はんだ被膜形成可能限界）は、ソルダーペーストの粘度・はんだ粒子径および塗布条件にもよるが、一般にパッドまたはリードにはんだ皮膜形成可能な最小幅は高々０．１ｍｍ、隣接ピッチは０．１５ｍｍと言われており、特に、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小微細電子回路にブリッジやミッシングなく厚さ３~１５μｍの均一性の良好なはんだ被膜またははんだ皮膜を安定して形成させることは至難である。 Also, (B) the solder paste coating / fusion method has been widely used for a long time, and has been widely used even today, and the surface other than the pad or lead is protected with a solder resist film, and the pad or lead portion Reflow after the solder paste (cream solder) is applied to the pad or lead by screen printing etc. using a mask with an opening corresponding to the pad or lead position. The solder paste of 20-80μmφ in the solder paste is melted and fused while improving solder wettability by removing the oxide film on the pad or lead surface using the reducing power of the flux present in the solder paste. Thus, a solder film or a solder precoat film of 30 to 80 μm is formed. ( Patent Documents 3, 4, and 5)
However, in this solder paste application / fusion method, the limit of the solder paste application accuracy by screen printing or the like (the limit for forming a solder coating) depends on the viscosity of the solder paste, the solder particle diameter, and the application conditions. It is said that the minimum width at which a solder film can be formed on a lead is at most 0.1 mm and the adjacent pitch is 0.15 mm. In particular, the pad or lead width is 0.02 to 0.08 mm, and the adjacent pitch is 0.04 to 0.12 mm. It is extremely difficult to stably form a solder film or a solder film having a good uniformity of 3 to 15 μm in thickness without bridging or missing in such a minute and fine electronic circuit.
　一方、（Ｃ）錫またははんだめっき方式、及び（Ｄ）Ｎｉ／Ａｕめっき方式は、特に微小、微細回路のプリコートに優位な技術であり、近年、半導体ウエハーやインターポーザーの微小微細パッドのプリコートに適用されている。
このうち（Ｃ）法は、パッドまたはリード以外の表面がはんだレジストで保護され、パッドまたはリード部のみが露出している電子回路基板を、はんだ成分の金属イオンを含有するめっき液中で所望の厚さにめっきしてはんだ皮膜を形成させる方法で、例えば、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小微細電子回路に厚さ３~１５μｍの均一注のはんだプリコート皮膜を形成させることは可能である。
　しかしながら、主として水溶液を用いるため、電子回路基板中に水分子が浸透して、信頼性を低下させる品質上の問題と、前処理、水洗、後処理などを必要として、工程が長く複雑で処理時間も長く工程管理も大変なこと、従ってコストが高い難点がある。 On the other hand, the (C) tin or solder plating method and the (D) Ni / Au plating method are technologies that are particularly advantageous for pre-coating fine and fine circuits. Recently, they have been used for pre-coating micro-fine pads for semiconductor wafers and interposers. Has been applied.
Among these, the method (C) is a method in which an electronic circuit board in which the surface other than the pad or the lead is protected with a solder resist and only the pad or the lead part is exposed is desired in a plating solution containing a metal ion of a solder component. A method of forming a solder film by plating to a thickness, for example, a fine fine electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm and a thickness of 3 to 15 μm. It is possible to form a uniform solder precoat film.
However, since aqueous solutions are mainly used, water molecules permeate into the electronic circuit board, requiring quality problems that reduce reliability, pre-treatment, water washing, post-treatment, etc. However, the process management is long and the cost is high.
　同様に、（Ｄ）法のＮｉ／Ａｕめっきの目的は主として、ウエハーなどのシリコン上のアルミ蒸着電極パッドの場合のように、電極内部に錫またははんだ成分中の元素が内部拡散するのを防止するために、拡散防止膜として下地ニッケルめっきなどを施した後、めっきされたニッケル表面の酸化防止とはんだ付け性を改善するためにその上に薄い金めっきを被覆するもので、この場合も（Ｃ）法と同様、例えば、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小微細電子回路に厚さ３~１５μｍの均一性のはんだプリコート皮膜を形成させることは可能である。但し、（Ｄ）法の場合は金めっきの上に更に（Ｂ）法の手順を付加して、はんだ皮膜を形成させることも広く行われているが、この場合は上記（Ｂ）法の説明で述べた通り、一般にパッドまたはリード最小幅０．１ｍｍ、隣接ピッチは０．１５ｍｍが限界であり、例えば、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍのような微小微細電子回路に厚さ３~１５μｍの均一性のはんだ皮膜をブリッジやミッシングなく安定して形成させることは殆ど不可能である。 Similarly, the purpose of Ni / Au plating in the (D) method is mainly to prevent internal diffusion of elements in the tin or solder components inside the electrode, as in the case of an aluminum evaporated electrode pad on silicon such as a wafer. In order to improve the anti-oxidation and solderability of the plated nickel surface after applying a base nickel plating or the like as a diffusion prevention film, a thin gold plating is coated on the surface. Similar to the method C), for example, a uniform solder precoat film with a thickness of 3 to 15 μm is applied to a minute fine electronic circuit having a pad or lead width of 0.02 to 0.08 mm and an adjacent pitch of 0.04 to 0.12 mm. It is possible to form. However, in the case of the method (D), the procedure of the method (B) is further added on the gold plating to form a solder film, but in this case, the explanation of the method (B) is performed. In general, the minimum pad or lead width is 0.1 mm and the adjacent pitch is 0.15 mm. For example, the pad or lead width is 0.02 to 0.08 mm and the adjacent pitch is 0.04 to 0.12 mm. It is almost impossible to stably form a uniform solder film having a thickness of 3 to 15 μm on such a minute and fine electronic circuit without bridging or missing.
　また更に、ホットエアーレベリング方法及びホットリキッドレベリング方法ではんだ被膜を形成したものは、近年鉛フリーはんだ合金として広く普及している錫銅系はんだ合金、錫銀系はんだ合金、錫銀銅系はんだ合金などにおいては、凝固時に１~１０数μｍ程度の針状または粒状の錫銅または錫銀の金属間結晶（ＩＭＣ）が偏析してはんだ接合界面近傍のはんだ層内部に散在するため、特にはんだ厚さが１０μｍ以下のレベリング後のはんだ皮膜の表面はデコボコになり、はんだ厚さのばらつきも大きく、表面外観もまだら模様を呈する難点がある。 Furthermore, the ones in which the solder coating is formed by the hot air leveling method and the hot liquid leveling method are tin-copper solder alloys, tin-silver solder alloys, tin-silver-copper solder alloys that have been widely used as lead-free solder alloys in recent years. In particular, when solidifying, needle-like or granular tin-copper or tin-silver intermetallic crystals (IMC) of about 1 to several tens μm are segregated and scattered in the solder layer in the vicinity of the solder joint interface. The surface of the solder film after leveling with a thickness of 10 μm or less becomes uneven, the solder thickness varies greatly, and the surface appearance has a mottled pattern.
　しかしながら、製造効率が悪く信頼性に劣る前記（Ｃ）、（Ｄ）を除いて、現行のはんだ接合技術を組合わせても、現状では、はんだプリコート皮膜形成可能な電子回路の最小幅は、パッドまたはリード幅で高々０．１ｍｍ、隣接回路ピッチとしては０．１５ｍｍが限界であり、それ以下の幅と隣接ビッチの微小微細はんだ接合電子回路形成は、（Ｃ），（Ｄ）の電気めっき方式以外は未だに完全には実用化されていない。
　このため、特に高信頼性が求められる航空機用や車載用の電子回路基板、電子部品、半導体装置及び電子装置の更なる小型軽量化のためにも、例えば、パッド幅が０．０８ｍｍ以下、隣接ピッチ０．１２ｍｍ以下の微小微細回路が望まれているが、現行方式のはんだ皮膜形成方法では、譬え局部的にはんだが付着してもブリッジを生ずる確率が高く、大半ははんだ不着（ミッシング）を多発するため、更なる微小微細小型軽量化のネックになっている。
特開平６−２５２５４２号 特開平８−３７３６１号 特開平１０−３２２００７号 特開平９−３０７２２３号 特開平１１−３０７５６５号 However, with the exception of the above (C) and (D), which are inferior in manufacturing efficiency and inferior in reliability, at present, the minimum width of an electronic circuit capable of forming a solder precoat film is the pad Alternatively, the lead width is at most 0.1 mm, and the adjacent circuit pitch is limited to 0.15 mm, and the width less than that and the minute pitch solder joint electronic circuit formation of the adjacent bit can be formed by the electroplating method of (C) and (D). Other than that, it has not been fully put into practical use yet.
For this reason, in order to further reduce the size and weight of electronic circuit boards, electronic components, semiconductor devices, and electronic devices for aircraft and automobiles that require particularly high reliability, for example, the pad width is 0.08 mm or less and adjacent A micro-fine circuit with a pitch of 0.12 mm or less is desired, but with the current method of forming a solder film, there is a high probability that a bridge will be formed even if the solder is locally attached, and most of the soldering does not occur (missing). Since it occurs frequently, it has become a bottleneck for further miniaturization, miniaturization, and weight reduction.
JP-A-6-252542 JP-A-8-37361 JP 10-322007 A JP-A-9-307223 JP-A-11-307565
　本発明は、電子部品のパッドまたはリードにはんだ皮膜を形成する方法における前記従来方法の難点、即ち、パッドまたはリード幅０．０８ｍｍ以下・隣接ピッチが０．１２ｍｍ以下の微小微細狭ピッチ高密度電子回路への錫またははんだ皮膜形成困難な問題を解決して品質信頼性の高い均一な錫またははんだ皮膜を形成させる技術を提供するものである。 The present invention has a difficulty in the conventional method for forming a solder film on a pad or lead of an electronic component, that is, a fine fine narrow pitch high density electron having a pad or lead width of 0.08 mm or less and an adjacent pitch of 0.12 mm or less. The present invention provides a technique for forming a uniform tin or solder film with high quality and reliability by solving the difficulty of forming tin or solder film on a circuit.
　本発明は、パッドまたはリード以外の表面がソルダーレジスト膜で保護され、パッドまたはリードのみが露出している電子回路基板または電子部品連結体（以下、ワークという）の清浄化された全ての前記パッドまたはリード表面に、錫またははんだ微粒子を少なくとも１個以上搭載させる第１ステップと、前記錫またははんだ微粒子を前記パッドまたはリード表面に融着させて錫またははんだ皮膜を形成させる第２ステップと、錫またははんだ皮膜表面に高温の有機脂肪酸溶液を吹付けて余剰に付着した前記錫またははんだを吹き落し除去する第３ステップにより、前記パッドまたはリードに厚さ２~２０μｍで、かつ厚さのばらつきが±３μｍ以下の均一な錫またははんだ皮膜を形成させるものである。 In the present invention, all the above-mentioned pads that have been cleaned of an electronic circuit board or an electronic component assembly (hereinafter referred to as a workpiece) in which surfaces other than the pads or leads are protected with a solder resist film and only the pads or leads are exposed. Or a first step of mounting at least one tin or solder fine particle on the lead surface; a second step of fusing the tin or solder fine particle to the pad or lead surface to form a tin or solder film; Alternatively, by spraying a hot organic fatty acid solution onto the surface of the solder film to blow off and remove the excessively attached tin or solder, the pad or the lead has a thickness of 2 to 20 μm and a variation in thickness. A uniform tin or solder film of ± 3 μm or less is formed.
　更に詳しく述べると、本発明の第１ステップにおいては、パッドまたはリード表面が充分に清浄で酸化防止の保護皮膜（例えばＯＳＰ処理済のイミダゾール皮膜や有機脂肪酸の化学吸着した保護膜など）があれば、直接錫またははんだ微粒子を全てのパッドまたはリード表面に少なくとも１個以上搭載して、本発明の第２ステップで前記パッドまたはリード表面に融着させると、これが「核」となり周囲の溶融錫または溶融はんだを呼び込み融合して錫またははんだ層の厚みを増すことが出来る。
　この「核」が必要な理由は、溶融錫液または溶融はんだ液固有の表面張力によるぬれ角の問題、あるいは窪みになっているパッドまたはリード上に滞留する気泡の問題で、前記「核」がないと特に極細幅のパッドまたはリード表面に溶融錫または溶融はんだ液が直接接触することができないためである。
　例えば、幅２０~６０μｍ、隣接ピッチ４０~１００μｍの微小微細電子回路基板または電子部品連結体においては、はんだレジスト膜と開口しているパッドまたはリード面との高さの差（段差）が通常１０~３０μｍもあり、従来法である前記（Ａ）法（溶融はんだ浴浸漬処理法）では該溶融錫液または溶融はんだ液の表面張力によるぬれ角の問題、あるいは窪みになっているパッドまたはリード上に滞留する気泡の問題などで、パッドまたはリードに溶融錫または溶融はんだが極めて付着し難く、また、従来法の（Ｂ）法（ソルダーペースト塗布・融着方式）でもスクリーン印刷でソルダーペーストを前記微小幅のパッドまたはリード全てに完全に（１００％）充填することは非常に難しい。 More specifically, in the first step of the present invention, if the pad or lead surface is sufficiently clean and has an anti-oxidation protective film (such as an OSP-treated imidazole film or an organic fatty acid chemically adsorbed protective film). When at least one tin or solder fine particle is directly mounted on all pads or lead surfaces and fused to the pads or lead surfaces in the second step of the present invention, this becomes a “nucleus” and the surrounding molten tin or Molten solder can be attracted and fused to increase the thickness of the tin or solder layer.
This “nucleus” is necessary because of the problem of the wetting angle due to the surface tension inherent in the molten tin solution or the molten solder solution, or the problem of bubbles remaining on the recessed pad or lead. Otherwise, the molten tin or the molten solder solution cannot be brought into direct contact with the surface of the extremely narrow pad or lead.
For example, in a micro-fine electronic circuit board or an electronic component assembly having a width of 20 to 60 μm and an adjacent pitch of 40 to 100 μm, the height difference (step) between the solder resist film and the opened pad or lead surface is usually 10 There is also ~ 30 μm, and in the conventional method (A) (molten solder bath dipping method), there is a problem of the wetting angle due to the surface tension of the molten tin solution or molten solder solution, or on the pad or lead that is indented. Due to the problem of air bubbles staying in the surface, molten tin or molten solder is very difficult to adhere to the pad or lead, and the solder paste is applied by screen printing in the conventional method (B) (solder paste application / fusion method). It is very difficult to completely (100%) fill all the very small pads or leads.
　一方、パッドまたはリード表面が必ずしも清浄でなく酸化している場合には、本発明の第１ステップとして、フラックスを介して錫またははんだ微粒子を少なくとも１個以上全てのパッドまたはリードに搭載する。
　この場合のフラックスは通常のはんだフラックスでも良いが、品質信頼性を重視する場合は腐食性のある塩素含有系フラックスは好ましくない。
　特に、パルミチン酸ニッケル／またはパルミチン酸コバルトなどを含有するフラックス（日本特許第４３８９１１２号）などを使用すると、電子部品、電子装置の高温暴露後に錫またははんだ接合界面に経時的に生ずる所謂カーケンダルボイド（マイクロボイド）を生じ難く、従って、耐熱耐衝撃破断性に優れた高信頼性はんだ接合が可能である。
　このケースでフラックスを使用する目的は、パッドまたはリード表面の残存酸化物を除去することと、錫またははんだ微粒子をフラックスに粘着させること、更に、この粘着した前記微粒子をぬれ性よく確実にパッドまたはリード表面に融着させることにある。 On the other hand, when the pad or lead surface is not necessarily clean and oxidized, as a first step of the present invention, at least one or more tin or solder fine particles are mounted on all the pads or leads via a flux.
The flux in this case may be a normal solder flux, but a corrosive chlorine-containing flux is not preferred when quality reliability is important.
In particular, when a flux containing nickel palmitate / or cobalt palmitate (Japanese Patent No. 4389112) or the like is used, a so-called Kirkendall void that occurs over time at the tin or solder joint interface after high temperature exposure of electronic components and electronic devices. (Microvoids) hardly occur, and therefore, highly reliable solder joints excellent in heat and shock resistance and fracture resistance are possible.
The purpose of using the flux in this case is to remove residual oxide on the pad or lead surface, to adhere tin or solder fine particles to the flux, and to ensure that the adhered fine particles have good wettability. It is to be fused to the lead surface.
　また、フラックスを前記パッドまたはリード表面に介在させる方法は、ブラシやロールやスキージーで塗布しても良いし、フラックスを溶媒で希釈してスプレーで噴霧塗着させてもよい。また、フラックスを介在させる個所は全てのパッド及びリード表面が必須であるが、それ以外のソルダーレジスト面、あるいはワーク全面に万遍なく塗着させても特に支障はない。 Further, as a method of interposing the flux on the surface of the pad or the lead, it may be applied with a brush, a roll or a squeegee, or the flux may be diluted with a solvent and sprayed with a spray. Further, all the pads and lead surfaces are indispensable for the place where the flux is interposed, but there is no particular problem even if the solder resist surface or the entire work surface is uniformly applied.
　本発明の第１ステップに用いる錫またははんだ微粒子は、開口露出している微細なパッドまたはリードの幅より小さい粒子径の微粒子を１質量％以上含有することが重要である。粒子径がこれより大きすぎると、前述の通り、ソルダーレジストの高い壁（一般的には、厚さで１０~３０μｍ）で取り囲まれているパッドまたはリード開口部内に錫またははんだ微粒子が入らないため、本発明の第２ステップにおいてパッドまたはリード表面に錫またははんだ微粒子を融着させることが難しくなるからである。
　望ましくは、前記パッドまたはリードの露出している幅（開口径）の１／２以下の粒子径の微粒子を１０％以上含有していることが効率的で良い。
　また、前記微粒子の形状としては真球状で表面が平滑なものが転がり性および融着時に気体の巻き込みが少ないので好ましい。また、表面が汚染していないこと、更には酸化していないことが接合信頼性上から望ましい。 It is important that the tin or solder fine particles used in the first step of the present invention contain 1% by mass or more of fine particles having a particle diameter smaller than the width of the fine pad or lead exposed in the opening. If the particle diameter is too large, as described above, tin or solder particles do not enter the pad or lead opening surrounded by the high wall of the solder resist (generally 10 to 30 μm in thickness). This is because it becomes difficult to fuse tin or solder fine particles to the pad or lead surface in the second step of the present invention.
Desirably, it is efficient to contain 10% or more of fine particles having a particle size of 1/2 or less of the exposed width (opening diameter) of the pad or lead.
Further, as the shape of the fine particles, a spherical shape and a smooth surface are preferable because the rolling property and gas entrainment at the time of fusion are small. Further, it is desirable from the viewpoint of bonding reliability that the surface is not contaminated and further not oxidized.
　第１ステップにおける錫またははんだ微粒子の散布方法は、例えば、パッドまたはリード幅が０．０８ｍｍ以下で、隣接回路ピッチが０．１２ｍｍ以下の微小微細狭ピッチ高密度電子回路で構成されているワークの場合、上方から細かいメッシュの金網でできた篩、上部が広く下部に行くほど先端が細く狭まったロート状の容器、あるいは市販の粉末用散布装置や先端部に噴射散布ノズルを有する容器などに、固体の錫またははんだ粒子を入れて、上部から前記ワークの全てのパッドまたはリード表面上に付着するように散布する。
　その際、通常のメタルマスクを使用して上部から散布しても良いし、スクリーン印刷のようにスキージーを使って塗布しても良く、またはブラシを使用して塗布しても良い。更には、例えば、パッドまたはリード幅が２０~６０μｍで、隣接回路ピッチが４０~１００μｍの微小微細狭ピッチ高密度電子回路で構成されているワークの場合、図１のようにワーク１を振動させながら、上部に設置した粉末散布装置２を走査させながらノズル３から錫またははんだ微粒子４を散布して搭載しても良い。この場合、ワーク１を５~６０度の範囲で傾斜をつけて配置しても良い。
　また、パッドまたはリード表面が清浄でない場合は、希釈したフラックス中に前記微粒子を分散させてスプレー状に散布するか、ペースト状のフラックスと前記微粒子とを混練りしたものをパッドまたはリード表面に塗布すると良い。 The method of spraying tin or solder fine particles in the first step is, for example, for a work composed of a minute fine pitch high-density electronic circuit having a pad or lead width of 0.08 mm or less and an adjacent circuit pitch of 0.12 mm or less. In this case, a sieve made of a fine mesh wire mesh from above, a funnel container whose tip is narrowed and narrowed toward the lower part of the upper part, or a container having a spraying nozzle for commercially available powder or a spraying nozzle at the tip part, Solid tin or solder particles are added and spread from the top to adhere to all pads or lead surfaces of the workpiece.
At that time, it may be sprayed from the top using a normal metal mask, may be applied using a squeegee as in screen printing, or may be applied using a brush. Further, for example, in the case of a work composed of a minute fine pitch electronic circuit having a pad or lead width of 20 to 60 μm and an adjacent circuit pitch of 40 to 100 μm, the work 1 is vibrated as shown in FIG. However, the tin or solder fine particles 4 may be sprayed and mounted from the nozzle 3 while scanning the powder spraying device 2 installed on the top. In this case, the work 1 may be arranged with an inclination in the range of 5 to 60 degrees.
If the surface of the pad or lead is not clean, the fine particles are dispersed in a diluted flux and sprayed, or a paste-like flux and the fine particles kneaded are applied to the pad or lead surface. Good.
　また、散布する前記錫またははんだ微粒子の材質種類としては、電子部品に広く使用されている通常のはんだ、即ち、純錫、錫鉛系合金、錫銀銅系合金、錫亜鉛系合金、錫ビスマス系合金、更にはこれらの母合金にニッケル、ゲルマニウム、インジウム、アンチモン、リンなど添加したはんだで良い。但し、環境問題の観点からは鉛フリーはんだが望ましい。
　このうち、特に、電子部品、電子装置の高温暴露後に錫またははんだ接合界面に経時的に生ずる所謂カーケンダルボイド（マイクロボイド）を抑止し、耐熱耐衝撃破断性に優れた高信頼性はんだ接合を目的とする場合には、酸素濃度５ｐｐｍ以下の錫またははんだ合金からなる微粒子を使用することが望ましい。とりわけニッケル０．００５~０．５質量％と、ゲルマニウム０．００１~０．１質量％またはリン０．００３~０．１質量％のいずれか１種以上を添加した酸素濃度５ｐｐｍ以下のはんだ合金が良い。
　特に、酸素濃度が２ｐｐｍ以下の錫またははんだ微粒子を使用した場合は、１２０℃以上の高温で長期加熱後のカーケンダルボイド発生をほぼ皆無にでき、長期加熱後の耐衝撃破断性に優れた品質信頼性の高い電子部品、半導体装置、及び電子装置が得られる。
　また、半導体装置または電子装置の特性を損なわないために、特に高温でのはんだ接合を嫌う場合は、錫４２質量％、ビスマス５８質量％の錫ビスマス母合金に、ニッケル０．００５~０．５質量％と、ゲルマニウム０．００１~０．１質量％またはリン０．００３~０．０５質量％のいずれか１種以上とを添加したはんだ合金を使用すれば、高々１４０~１８０℃程度の比較的低温でのはんだ接合が可能であり、しかも、前記微量のニッケルとゲルマニウム添加の効果で、形成されたはんだ皮膜の表面は酸化し難く、かつ仕上がり表面に凹凸のない平滑なはんだ皮膜になるメリットもある。
　特に、微量のニッケルを添加した錫またははんだを使用すると、接合界面にニッケルバリヤー層が形成されて、パッドまたはリードの銅が溶融はんだ液の中に溶出拡散抑制／防止する効果があり、その使用が望ましい。 In addition, as the material type of the tin or solder fine particles to be dispersed, normal solder widely used in electronic parts, that is, pure tin, tin-lead alloy, tin-silver-copper alloy, tin-zinc alloy, tin bismuth, etc. Further, a solder obtained by adding nickel, germanium, indium, antimony, phosphorus, or the like to these base alloys or these mother alloys may be used. However, lead-free solder is desirable from the viewpoint of environmental problems.
Of these, the so-called Kirkendall voids (microvoids) that occur over time at the tin or solder joint interface after high-temperature exposure of electronic components and electronic devices are suppressed, and highly reliable solder joints with excellent thermal shock resistance and fracture resistance For the purpose, it is desirable to use fine particles made of tin or a solder alloy having an oxygen concentration of 5 ppm or less. In particular, a solder alloy having an oxygen concentration of 5 ppm or less to which 0.005 to 0.5 mass% of nickel and one or more of 0.001 to 0.1 mass% of germanium or 0.003 to 0.1 mass% of phosphorus are added. Is good.
In particular, when tin or solder fine particles with an oxygen concentration of 2 ppm or less are used, the generation of Kirkendall voids after long-term heating at a high temperature of 120 ° C. or higher can be almost eliminated, and the quality is excellent in impact fracture resistance after long-term heating. A highly reliable electronic component, semiconductor device, and electronic device can be obtained.
In order not to impair the characteristics of the semiconductor device or the electronic device, in particular, when solder bonding at a high temperature is disliked, a nickel bismuth master alloy of 42 mass% tin and 58 mass% bismuth is added with 0.005 to 0.5 nickel. If a solder alloy added with 1% by mass and any one or more of 0.001 to 0.1% by mass of germanium or 0.003 to 0.05% by mass of phosphorus is used, a comparison of at most 140 to 180 ° C. It is possible to solder at low temperatures, and the effect of adding a small amount of nickel and germanium makes the surface of the formed solder film difficult to oxidize and a smooth solder film with no irregularities on the finished surface. There is also.
In particular, when tin or solder added with a small amount of nickel is used, a nickel barrier layer is formed at the joint interface, and the copper of the pad or lead is effective in suppressing / preventing elution and diffusion in the molten solder solution. Is desirable.
　散布する錫またはんだ微粒子の搭載量は所望の錫またははんだ皮膜厚さと同じ厚さになるように搭載することは至難であるので、それより過剰に搭載すると良い。あるいはワークの開口しているパッドまたはリードの直上部のみならず、その周辺のソルダーレジスト部の上にも前記微粒子を搭載するか、極端な場合はワーク全面に前記微粒子を過剰に搭載しても良い。
　これらの場合は、当然、本発明の第２ステップで前記微粒子をワークのパッドまたはリードに融着した際に隣接回路とブリッジしたり、あるいはソルダーレジスト上でボール状になって乗る形で存在することになるが、これらの余剰の錫またははんだは本発明の第３ステップにより除去されて、前記パッドまたはリード部にのみ所望の錫またははんだ皮膜が形成されて残るので問題ない。
　但し、パッドまたはリードの銅厚が非常に薄い場合（例えば５μ以下）は、所謂「銅食われ」により、溶融はんだ中に銅が溶解拡散してパッドまたはリードが消失する可能性があるので、その場合のパッドまたはリードへの錫またははんだ微粒子の搭載量は高さで５μを超えないことが望ましい。
　一方、錫またははんだ微粒子の搭載量が過少の場合は、所望の錫またははんだ皮膜厚さを形成することが出来ないので、この場合には、本発明の第２のステップで前記微粒子を「核」としてワークのパッドまたはリードに融着させた後、別に用意した溶融錫浴または溶融はんだ浴にワークを浸漬するか、溶融錫液または溶融はんだ液をワークのパッドまたはリードに吹き付けて、前記パッドまたはリード部の前記融着錫またははんだ「核」上に更に充分な量の錫またははんだを上乗せする。その際、上層の高温の有機脂肪酸溶液（例えば、パルミチン酸溶液など）を通過させて、下層に溶融錫浴または溶融はんだ浴にワーク１を浸漬するか、溶融錫液または溶融はんだ液と高温の有機脂肪酸溶液（例えば、パルミチン酸溶液など）とをワークのパッドまたはリードに吹き付けると、上乗せされる錫またははんだの密着性ならびに形成された錫またははんだ皮膜内の酸化物汚染を回避できるので、好ましい。
　この場合も、微細回路では当然ブリッジが形成されるが、上述と同様にこれら余剰の錫またははんだは本発明の第３ステップにより除去されて、前記パッドまたはリード部にのみ所望の錫またははんだ皮膜が形成されて残るので問題はない。 Since it is difficult to mount the tin or the fine particles to be dispersed so as to have the same thickness as the desired tin or solder film thickness, it is preferable to mount excessively. Alternatively, the fine particles may be mounted not only on the pads or leads that are open on the workpiece but also on the solder resist portion around the pads, or in extreme cases, the fine particles may be excessively loaded on the entire surface of the workpiece. good.
In these cases, naturally, when the fine particles are fused to the work pad or lead in the second step of the present invention, they are bridged with an adjacent circuit, or exist in the form of a ball on the solder resist. However, the excess tin or solder is removed by the third step of the present invention, and there is no problem because a desired tin or solder film is formed only on the pad or lead portion.
However, when the copper thickness of the pad or lead is very thin (for example, 5 μm or less), the so-called “copper erosion” may cause copper to dissolve and diffuse in the molten solder, and the pad or lead may disappear. In this case, it is desirable that the amount of tin or solder fine particles mounted on the pad or lead does not exceed 5μ in height.
On the other hand, if the amount of tin or solder fine particles is too small, the desired tin or solder film thickness cannot be formed. In this case, the fine particles are “nucleated” in the second step of the present invention. After the workpiece is fused to the pad or lead of the workpiece, the workpiece is immersed in a separately prepared molten tin bath or molten solder bath, or molten tin solution or molten solder solution is sprayed onto the workpiece pad or lead, and the pad Alternatively, a sufficient amount of tin or solder is placed on the fused tin or solder “core” of the lead portion. At that time, the upper layer high-temperature organic fatty acid solution (for example, palmitic acid solution or the like) is passed, and the work 1 is immersed in the molten tin bath or the molten solder bath in the lower layer, or the molten tin solution or the molten solder solution and the high temperature It is preferable to spray an organic fatty acid solution (for example, palmitic acid solution, etc.) on a pad or lead of a work because adhesion of tin or solder to be added and oxide contamination in the formed tin or solder film can be avoided. .
In this case as well, a bridge is naturally formed in the fine circuit, but as described above, these excess tin or solder is removed by the third step of the present invention, and a desired tin or solder film is formed only on the pad or lead portion. Since it is formed and remains, there is no problem.
　尚、パッドまたはリード幅が８０μｍ以上の回路であれば、本発明の第１ステップで錫またははんだ微粒子の散布は必ずしも行う必要はなく、必要によりフラックスを使用して別の溶融錫または溶融はんだ液槽に直接浸漬するだけでも、ワークのパッドまたはリードに錫またははんだ皮膜を形成することは可能である。 If the circuit has a pad or lead width of 80 μm or more, it is not always necessary to spray tin or solder fine particles in the first step of the present invention. If necessary, another molten tin or molten solder solution can be used by using a flux. It is possible to form a tin or solder film on the pad or lead of the work simply by dipping directly in the bath.
　本発明の第２ステップにおける前記錫またははんだ微粒子を前記パッドまたはリード表面に融着させる方法としては、一般のオーブン（加熱炉）、リフロー炉、フロー炉、更には赤外線または遠赤外線ヒーター加熱などの加熱雰囲気内で加熱して融着させても良いし、あるいはホットプレート上で加熱して融着させても良い。更に、前記錫またははんだ微粒子の融点以上の高温の有機脂肪酸溶液（例えばパルミチン酸溶液など）のような非酸化性液体中で融着させるのも接合時に酸素の巻き込みがなく接合界面の品質信頼性上極めて有効である。
　前記融着させる温度条件としては、前記錫またははんだ微粒子の融点＋１０~５０℃の範囲内の温度に温度制御して、できるだけ短時間で融着させると良い。その際、余熱も含めてワーク全体が出来るだけ均一な温度になるよう制御して、融着時間は５秒以内、望ましくは３秒以下にすると、銅食われによるパッドまたはリードの消失を回避できる。 As a method for fusing the tin or solder fine particles to the pad or lead surface in the second step of the present invention, a general oven (heating furnace), a reflow furnace, a flow furnace, an infrared or far infrared heater heating, etc. It may be heated and fused in a heating atmosphere, or may be heated and fused on a hot plate. Furthermore, it is possible to fuse in a non-oxidizing liquid such as a high-temperature organic fatty acid solution (for example, palmitic acid solution) higher than the melting point of the tin or solder fine particles. It is extremely effective.
As the temperature condition for the fusion, the temperature is controlled to a temperature within the range of the melting point of the tin or solder fine particles +10 to 50 ° C., and the fusion is performed in as short a time as possible. At that time, by controlling the temperature of the entire work including the remaining heat to be as uniform as possible, and making the fusion time within 5 seconds, preferably 3 seconds or less, it is possible to avoid loss of pads or leads due to copper erosion. .
　本発明の第３ステップに用いる有機脂肪酸溶液は、カプロン酸、カプリル酸、２−エチルヘキ酸、ノナン酸、カプリン酸、ウンデカン酸、ミリスチン酸、パルミチン酸、マルガリン酸、ステアリン酸、オレイン酸、リノール酸、リノレン酸、アラキジン酸、アラキドン酸、ベヘン酸、リグノセリン酸、セロチン酸、モンタン酸、メリシン酸、などのカルボキシル基（−ＣＯＯＨ）を有する有機脂肪酸溶液がよい。これらの内、望ましくは１８０~３００℃で使用する溶媒に溶解し分解などせず安定している有機脂肪酸がよい。沸点が低い有機脂肪酸の場合は高圧にして使用することも可能であるが、安全性、実用性の点で好ましくはない。
　経済性や取扱い上から工業的により実用に適するものは、例えば、炭素数１３~２０の有機脂肪酸、即ち、ミリスチン酸、パルミチン酸、マルガリン酸、ステアリン酸、オレイン酸、リノール酸、リノレン酸、アラキジン酸、アラキドン酸などであり、本発明の目的に合致した効果が大きく、特に有用である。
　有機脂肪酸は炭素数１２以下でも使用可能ではあるが吸水性があり、高温で使用する関係からあまり好ましくないこと、更に余剰のはんだ除去後の錫またははんだ表面に保護膜としてコーティングされても吸水性があるため長期保存時の品質に障害をもたらすこともあり、必ずしも好ましくない。また、炭素数２１以上の有機脂肪酸でも使用は可能であるが、融点が高いこと及び処理後のはんだ表面の防錆効果もやや不充分になる。
　特に望ましいのは、工業的にも大量に生産され、多分野で使用されていて、入手もし易い炭素数１６のパルミチン酸、炭素数１８のステアリン酸が最適であり、そのいずれか１種以上を１~８０重量％と残部が高温領域で安定な油系溶媒からなる、液温１８０~３００℃の溶液を使用すると本発明の効果も大きい。 The organic fatty acid solution used in the third step of the present invention is caproic acid, caprylic acid, 2-ethylhexic acid, nonanoic acid, capric acid, undecanoic acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid An organic fatty acid solution having a carboxyl group (—COOH) such as linolenic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, and melissic acid is preferable. Among these, organic fatty acids which are preferably dissolved in a solvent used at 180 to 300 ° C. and stable without decomposition are preferred. In the case of an organic fatty acid having a low boiling point, it can be used at a high pressure, but it is not preferable in terms of safety and practicality.
Those that are industrially more suitable for practical use in terms of economy and handling are, for example, organic fatty acids having 13 to 20 carbon atoms, that is, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidin. Acid, arachidonic acid and the like, which are particularly useful because they have a great effect in accordance with the object of the present invention.
Although organic fatty acids can be used even with carbon atoms of 12 or less, they have water absorbency and are not very desirable due to their use at high temperatures, and even if they are coated as a protective film on the surface of tin or solder after excess solder is removed Therefore, the quality during long-term storage may be hindered, which is not always preferable. Further, although organic fatty acids having 21 or more carbon atoms can be used, the melting point is high and the rust preventive effect on the solder surface after treatment is slightly insufficient.
Particularly desirable are industrially produced in large quantities in large quantities, used in various fields, and easily available, such as 16 carbon atoms of palmitic acid and 18 carbon atoms of stearic acid, and any one or more of them are used. The use of a solution having a liquid temperature of 180 to 300 ° C. composed of an oil-based solvent that is 1 to 80% by weight and the balance is stable in a high temperature region, also has a great effect of the present invention.
　本発明の第３ステップの余剰錫またははんだ除去にカルボキシル基（−ＣＯＯＨ）を有する有機脂肪酸溶液を使用する目的は、第１にワークに存在するブリッジ等の余剰錫またははんだを有機脂肪酸の活性力によりはじき落とす効果が他の有機化合物より非常に大きいこと、第２に前記融着した錫またははんだ層内の不純物や酸化金属を洗浄する効果があり、かつ余剰の錫またははんだを除去したあとのパッドまたはリード上に残存した錫またははんだ表面に前記有機脂肪酸が化学吸着して酸化防止保護膜が形成されること、第３にワークの表面に付着した不要な塵埃や錫またははんだ微粒子を洗い流し落とす効果が極めて大きいこと、に因る。このうち、特に第１の余剰のはんだをはじき落とす効果はいろいろな有機化合物を試行錯誤した結果、発明者らが新たに発見した現象である。 The purpose of using the organic fatty acid solution having a carboxyl group (—COOH) for the removal of surplus tin or solder in the third step of the present invention is as follows. The effect of scavenging off is much greater than that of other organic compounds, and secondly, there is an effect of cleaning impurities and metal oxides in the fused tin or solder layer, and after removing excess tin or solder. The organic fatty acid is chemisorbed on the surface of tin or solder remaining on the pad or lead to form an anti-oxidation protective film, and third, unnecessary dust and tin or solder fine particles adhering to the surface of the workpiece are washed away. This is because the effect is extremely large. Among these, the effect of removing the first excess solder is a phenomenon newly discovered by the inventors as a result of trial and error of various organic compounds.
　有機脂肪酸溶液中の有機脂肪酸の濃度については１質量％以下でも効果はあるが、連続して大量に処理する場合は補充管理などが煩雑なこと、また８０質量％以上あるいは１００質量％単体液でも本発明の効果はあり使用可能であるが、発煙性と臭気の問題もきつくなるため、好ましくは５~８０質量％が良い。
　前記有機脂肪酸溶液の液温は前記第２ステップで形成された錫または溶融はんだ皮膜の溶融温度と同温度以上であることが必須条件であるが、上限温度は発火性、発煙性、安全性を考慮すると３２０℃程度であり、臭気の問題及び省エネを考慮すると、前記錫または溶融はんだ皮膜の溶融温度より１０~４０℃高い液温で有機脂肪酸溶液を使用することが望ましい。
　例えば、融点が２１７℃近辺の錫銀銅（Ａｇ３．０質量％、Ｃｕ０．５質量％、残部錫）３元系はんだ合金の場合であれば、使用する有機脂肪酸溶液の液温は２４０~２８０℃が最適である。この場合の余剰の錫またははんだ除去効率は、有機脂肪酸溶液の液温を２８０℃~３２０℃まで上げた場合と有意差はない。同様に、錫／ビスマス系はんだのような融点が１３９~１６０℃付近の低融点はんだの場合も、使用する有機脂肪酸溶液の液温は前記融点＋１０~４０℃の範囲で充分本発明の効果がある。２８０℃を超えると発火の危険性があるので、窒素雰囲気にすると良い。 The concentration of the organic fatty acid in the organic fatty acid solution is effective even if it is 1% by mass or less, but replenishment management is complicated when processing a large amount continuously, and even if it is 80% by mass or more or 100% by mass alone Although the effect of the present invention is available and can be used, the problem of smoke generation and odor is also severe, so 5 to 80% by mass is preferable.
The liquid temperature of the organic fatty acid solution is an essential condition that is equal to or higher than the melting temperature of the tin or molten solder film formed in the second step, but the upper limit temperature is ignitable, fuming, and safe. In consideration of the problem of odor and energy saving, it is desirable to use an organic fatty acid solution at a liquid temperature 10 to 40 ° C. higher than the melting temperature of the tin or molten solder film.
For example, in the case of a tin-silver-copper (Ag 3.0 mass%, Cu 0.5 mass%, balance tin) ternary solder alloy having a melting point near 217 ° C., the liquid temperature of the organic fatty acid solution used is 240 to 280. ° C is optimal. The excess tin or solder removal efficiency in this case is not significantly different from the case where the liquid temperature of the organic fatty acid solution is increased from 280 ° C. to 320 ° C. Similarly, even in the case of a low melting point solder having a melting point of around 139 to 160 ° C. such as tin / bismuth solder, the temperature of the organic fatty acid solution used is sufficiently within the range of the melting point +10 to 40 ° C. is there. If it exceeds 280 ° C, there is a risk of ignition, so a nitrogen atmosphere is recommended.
　また本発明に使用する有機脂肪酸の溶媒は、前記有機脂肪酸を溶かし、かつ前記高温領域で安定な溶媒であれば、鉱物油、植物油、合成油のいずれでもよいが、特に安定性、安全性、経済性、取扱い性の点でエステル合成油が最適である。高温で安定な溶媒を使用する目的と理由は、前記有機化合物の高温発煙性ならびに臭気の緩和抑制、更にははんだ接合処理後に過剰に付着した有機脂肪酸溶液を洗い落とす際の洗浄性がよいこと、また、若干ではあるが液粘性を下げ浸透性も改善される効果が大きいからである。その濃度は前記有機脂肪酸濃度により決まる。 The organic fatty acid solvent used in the present invention may be any of mineral oil, vegetable oil, and synthetic oil as long as it dissolves the organic fatty acid and is stable in the high temperature range. Ester synthetic oil is most suitable in terms of economy and handling. The purpose and reason for using a solvent that is stable at high temperature is that the organic compound emits high-temperature smoke and suppresses odor, and also has good cleanability when washing off excessively attached organic fatty acid solution after soldering treatment. This is because the effect of lowering the liquid viscosity and improving the permeability is large. The concentration is determined by the organic fatty acid concentration.
　次に本発明の第３ステップで前記有機脂肪酸溶液により余剰の錫またははんだを除去する方法を説明する。
　先ず最も単純な方法としては、図３のように、高温の前記有機脂肪酸溶液６にワーク１を単に垂直もしくは傾斜をつけて浸漬して、ワークに物理的な振動を与える方法（傾斜浸漬振動付与方法）である。この方法でも、第２のプロセスで生じたブリッジやソルダーレジスト上に存在する錫またははんだ球状物、更にはワークの表面に付着した不要な塵埃や錫またははんだ微粒子などの余剰の錫またははんだを洗い流し落として、ワークの微細回路のパッドまたはリード部のみに良好な錫またははんだ皮膜を形成できる。
　この場合のワークの傾斜角度は、前記ワークに付与する物理的振動の大小にもよるが、一般的には５~９０度まで効果がある。特に、望ましい傾斜角度は３０~９０度である。但し、パッドまたはリード表面上に残存形成された錫またははんだ皮膜厚さおよび形状はばらつきを生じ易く、特にプリコート皮膜のように２~１０μｍの厚さ内で±２μｍ以内に均一に仕上げることは難しい。また、例えば、パッドまたはリード幅が４０μｍ以下で隣接回路ピッチが６０μｍ以下の極細回路の場合はブリッジが局部的に残存することもあり、この傾斜浸漬方法には限界がある。 Next, a method for removing excess tin or solder with the organic fatty acid solution in the third step of the present invention will be described.
First, as the simplest method, as shown in FIG. 3, a work 1 is simply immersed vertically or inclined in the organic fatty acid solution 6 at a high temperature to give a physical vibration to the work (applying an inclined immersion vibration). Method). Even in this method, the tin or solder spheres existing on the bridge or solder resist generated in the second process, and unnecessary tin or solder such as unnecessary dust or tin or solder fine particles adhering to the surface of the workpiece are washed away. As a result, a good tin or solder film can be formed only on the pads or leads of the fine circuit of the workpiece.
In this case, the tilt angle of the workpiece is generally effective from 5 to 90 degrees, although it depends on the magnitude of physical vibration applied to the workpiece. In particular, a desirable inclination angle is 30 to 90 degrees. However, the thickness or shape of the tin or solder film remaining on the pad or lead surface is likely to vary, and it is particularly difficult to finish uniformly within ± 2 μm within a thickness of 2 to 10 μm as in the case of a precoat film. . Further, for example, in the case of an ultrafine circuit having a pad or lead width of 40 μm or less and an adjacent circuit pitch of 60 μm or less, a bridge may remain locally, and this inclined immersion method has a limit.
　また別の方法として、高温の前記有機脂肪酸溶液をワークに吹き付ける方法（単純吹付け方法）、あるいは高温の前記有機脂肪酸溶液中に浸漬したワークに前記有機脂肪酸溶液を吹付ける方法（浸漬吹付け方法）、更には高温の前記有機脂肪酸溶液中にワークを浸漬しながら液中でローラーまたはスキージーにより余剰の錫またははんだを掻き落す方法（浸漬平滑化方法）などがある。
　このうち、単純吹付け方法は、例えば図２のように、ノズル９から高温の有機脂肪酸溶液をワーク１に吹付けて、前記パッドまたは前記リードに余剰に付着している錫またははんだを吹き落として、前記パッドまたは前記リードに所望の均一な膜厚の錫またははんだ皮膜を形成させる。
　一方、浸漬吹付け方法は、例えば、図４のように、高温の前記有機脂肪酸溶液中に浸漬したワーク１を引き上げながら、上部にて貯液槽５の高温の有機脂肪酸溶液６を移送用ポンプ７で配管８を通して給液して、先端のノズル９からワーク１に高温の有機脂肪酸溶液６を吹付けることにより、第２ステップで生じたブリッジ１２（図８）やソルダーレジスト１０の上に存在する余剰の錫またははんだ球状物またはワークの表面に付着した塵埃などの不要物１４（図８）を短時間でより効果的に吹き落として、ワークの微細回路のパッドまたはリード部のみに良好な錫またははんだ皮膜を均一な厚さに制御して形成することができる。
　尚、図４では前記有機脂肪酸溶液６の吹付けは液外上部の気中で行う事例として示したが、有機脂肪酸溶液６中にノズル９を設置して吹付け処理を行っても同様の効果が得られる。
　ワークの余熱の有無の差と、処理時間に多少の差はあるが、結果的には単純吹付け方法と浸漬吹付け方法は効果的に錫またははんだ皮膜形成の出来栄えはほぼ同一である。 As another method, a method of spraying the organic fatty acid solution at a high temperature onto the workpiece (simple spraying method), or a method of spraying the organic fatty acid solution onto a workpiece immersed in the organic fatty acid solution at a high temperature (immersion spraying method) Further, there is a method of scraping excess tin or solder with a roller or a squeegee in the liquid while immersing the workpiece in the high-temperature organic fatty acid solution (immersion smoothing method).
Among these, the simple spraying method, for example, as shown in FIG. 2, sprays a hot organic fatty acid solution from the nozzle 9 onto the work 1 and blows off the tin or solder excessively attached to the pad or the lead. Then, tin or a solder film having a desired uniform film thickness is formed on the pad or the lead.
On the other hand, for example, as shown in FIG. 4, the immersion spraying method is a pump for transferring the hot organic fatty acid solution 6 in the liquid storage tank 5 in the upper part while pulling up the work 1 immersed in the hot organic fatty acid solution. 7 is supplied through the pipe 8 and sprayed with a high-temperature organic fatty acid solution 6 from the nozzle 9 at the tip to the work 1, thereby existing on the bridge 12 (FIG. 8) and the solder resist 10 generated in the second step. The excess tin or solder ball or the unnecessary material 14 (FIG. 8) such as dust adhering to the surface of the work is blown off more effectively in a short time, and is good only for the pads or leads of the fine circuit of the work. A tin or solder film can be formed to a uniform thickness.
In FIG. 4, the spraying of the organic fatty acid solution 6 is shown as an example in the air in the upper part of the liquid. However, the same effect can be obtained by performing the spraying process by installing the nozzle 9 in the organic fatty acid solution 6. Is obtained.
Although there is a slight difference between the presence or absence of residual heat of the workpiece and the processing time, as a result, the simple spraying method and the immersion spraying method are effectively the same in the quality of tin or solder film formation.
　前記単純吹付け方法と浸漬吹付け方法において、ノズル９から吹付ける流速と吹付け処理時間は、所望する錫またははんだ皮膜の厚さ、ノズルの形状、吹掛け角度などの条件により異なるが、例えば、所望のプリコート被膜厚さが５±２μｍ、ノズルの先端形状がスリット状で開口幅０．５~３ｍｍＸ開口長さ５０~５００ｍｍの場合、吹付け角度がワーク１に対して４５~９０度、ワーク１の連続的引き上げ速度が毎秒１~２０ｃｍの場合、流速は０．５~４ｍ／秒、実質吹付け処理時間は０．５~５秒で充分である。
　また、吹付ける高温の前記有機脂肪酸溶液６の流速が速い程、得られる皮膜の膜厚は薄くなる。尚、ノズル形状は一般に市販されている散水用のノズルでも良く、その場合は噴射する有機脂肪酸溶液がワークの横幅に対して万遍なく一様に当たるように複数個のノズルを配置するか、１個以上のノズルを２次元的あるいは３次元的に走査させても良い。 In the simple spraying method and the immersion spraying method, the flow velocity sprayed from the nozzle 9 and the spraying treatment time vary depending on conditions such as a desired tin or solder film thickness, nozzle shape, spraying angle, etc. When the desired precoat film thickness is 5 ± 2 μm, the tip of the nozzle is slit and the opening width is 0.5 to 3 mm and the opening length is 50 to 500 mm, the spray angle is 45 to 90 degrees with respect to the workpiece 1, When the continuous pulling speed of the workpiece 1 is 1 to 20 cm per second, a flow rate of 0.5 to 4 m / second and a substantial spraying treatment time of 0.5 to 5 seconds are sufficient.
Moreover, the faster the flow rate of the high-temperature organic fatty acid solution 6 to be sprayed, the thinner the film thickness obtained. In addition, the nozzle shape may be a commercially available nozzle for watering. In that case, a plurality of nozzles may be arranged so that the organic fatty acid solution to be sprayed uniformly against the width of the workpiece. Two or more nozzles may be scanned two-dimensionally or three-dimensionally.
　あるいは、図５のように、高温の有機脂肪酸溶液６の液中に設置したリバースロール２２（前記ワーク１の引上げ方向と逆向きに回転）により、前記有機脂肪酸溶液６を前記ワーク１のパッドまたはリード部に吹付けることでも、ノズル吹付けの場合と同じ効果が得られる。
　この場合の吹付ける流速は、リバースロール２２の直径と回転速度を所望の錫またははんだの膜厚により適宜調整する必要があるが、例えば、所望の膜厚が５~２０μｍの場合、リバースロール径は６０~２００ｍｍφ、回転速度は６００~３０００ｒｐｍの範囲が良く、前記ロール径が大きい程、また回転速度が速い程、得られる錫またははんだ皮膜の膜厚は薄くなる。
　尚、このリバースロール２２の回転によりかき落とされる余剰の錫またははんだは微粒子となって該有機脂肪酸溶液中に散乱して処理済の上方パッドまたはリード部に再付着する危険性があるので、それを防止するためにリバースロール２２の上部ににバッフル２３を設置すると良い。また、ワーク１とリバースロール２２との間隙は０，１~５ｍｍ程度でよい。 Alternatively, as shown in FIG. 5, the organic fatty acid solution 6 is put on the pad of the work 1 or the reverse roll 22 (rotated in the direction opposite to the pulling direction of the work 1) installed in the liquid of the high-temperature organic fatty acid solution 6. By spraying on the lead part, the same effect as in the case of nozzle spraying can be obtained.
In this case, it is necessary to adjust the diameter and rotation speed of the reverse roll 22 according to the desired tin or solder film thickness. For example, when the desired film thickness is 5 to 20 μm, the reverse roll diameter Is preferably in the range of 60 to 200 mmφ and the rotation speed of 600 to 3000 rpm. The larger the roll diameter and the higher the rotation speed, the thinner the film thickness of the obtained tin or solder film.
It should be noted that excess tin or solder scraped off by the rotation of the reverse roll 22 may be dispersed in the organic fatty acid solution and reattached to the treated upper pad or lead portion. In order to prevent this, a baffle 23 may be installed on the upper portion of the reverse roll 22. The gap between the work 1 and the reverse roll 22 may be about 0, 1 to 5 mm.
　パッドまたはリードに被覆される錫またははんだ膜厚として２０μｍ以上でも可とする仕様であれば、上述のように高温の有機脂肪酸溶液に浸漬するだけで、従来法の（Ａ）溶融はんだ浴浸漬方式でブリッジしている回路パターンでも、有機脂肪酸溶液中を通過する際、有機脂肪酸の作用でブリッジは解消され、本発明の第３ステップの高温有機脂肪酸溶液吹付けレベラー処理の必要はなく、勿論、従来法のホットエアーレベラー処理またはホットリキッドレベラー処理の必要もない。ここに高温の有機脂肪酸が余剰の溶融錫または溶融はんだに対して特有の分離効果を発揮することを発明者らは知見した。
　しかしながら、パッドまたはリードに被覆される錫またははんだ膜厚が１~２０μｍの所謂プリコート皮膜形成の場合は、従来法のホットエアーレベラー処理またはホットリキッドレベラー処理をするか、本発明の第３ステップの処理をする必要があるが、特に、従来法のホットエアーレベラー処理またはホットリキッドレベラー処理では得られるプリコート皮膜厚のばらつきが非常に大きいのに対して、本発明方法では厚さのばらつきは遥かに小さく、均一なプリコート皮膜が得られ、有機脂肪酸溶液吹付けレベラー処理の効果が極めて大きいことが検証された。 As long as the thickness of tin or solder coated on the pad or lead is 20 μm or more, the conventional method (A) Molten solder bath immersion method can be used by simply immersing in a high-temperature organic fatty acid solution as described above. Even in the circuit pattern bridging in, when passing through the organic fatty acid solution, the bridge is eliminated by the action of the organic fatty acid, there is no need for the high-temperature organic fatty acid solution spraying leveler treatment of the third step of the present invention, of course, There is no need for conventional hot air leveler processing or hot liquid leveler processing. The inventors have found that high-temperature organic fatty acids exhibit a specific separation effect for excess molten tin or molten solder.
However, in the case of so-called precoat film formation with a tin or solder film thickness of 1 to 20 μm coated on the pad or lead, the conventional hot air leveler process or hot liquid leveler process is performed, or the third step of the present invention is performed. In particular, the variation of the precoat film thickness obtained by the hot air leveler treatment or the hot liquid leveler treatment of the conventional method is very large, whereas in the method of the present invention, the thickness variation is far larger. It was verified that a small and uniform precoat film was obtained, and that the effect of leveling treatment with an organic fatty acid solution was extremely large.
　また、更に、従来のホットエアーレベリング方法及びホットリキッドレベリング方法ではんだプリコート皮膜を形成したものは、近年鉛フリーはんだ合金として広く普及している錫銅系はんだ合金、錫銀系はんだ合金、錫銀銅系はんだ合金などにおいては、凝固時に１~１０数μｍ程度の針状または粒状の錫銅または錫銀の金属間結晶（ＩＭＣ）が偏析してはんだ接合界面近傍のはんだ層内部に散在するため、特にはんだプリコート厚さが１０μｍ以下のレベリング後のはんだプリコート被膜の表面はデコボコになり、はんだ厚さのばらつきが大きい難点もある。 In addition, the solder precoat film formed by the conventional hot air leveling method and hot liquid leveling method is a tin-copper solder alloy, a tin-silver solder alloy, a tin-silver solder that has been widely used as a lead-free solder alloy in recent years. In copper-based solder alloys, etc., needle-like or granular tin-copper or tin-silver intermetallic crystals (IMC) of about 1 to several tens of μm are segregated and scattered in the solder layer near the solder joint interface during solidification. In particular, the surface of the solder precoat film after leveling with a solder precoat thickness of 10 μm or less becomes uneven, and there is also a drawback that the solder thickness varies greatly.
　それを回避して、はんだプリコート厚さが１０μｍ以下でもほぼ完全に平滑な光沢表面に仕上がるようにするために、発明者らは試行錯誤的にいろいろ研究した結果、錫または共晶はんだであれば良いことを突き止めた。例えば、純錫に微量のニッケル０．００５~０．５質量％を含有し、微量のゲルマニウム０．００１~０．１質量％またはリン０．００３~０．１質量％のいずれか１種以上を含有し、残部錫からなるはんだ合金を用いて、本発明方法ではんだプリコート皮膜形成すれば、平滑良好なプリコート皮膜が得られることが判った。
　このほか、共晶はんだ、例えば、錫鉛合金（錫６３質量％、鉛３７質量％）、あるいは錫ビスマス合金（錫４２質量％、ビスマス５８質量％）、錫アンチモン合金などに、微量のニッケル０．００５~０．５質量％と、微量のゲルマニウム０．００１~０．１質量％またはリン０．００３~０．１質量％のいずれか１種以上とを添加したはんだを使用すれば、はんだプリコート皮膜厚さが２０μｍ以下でもほぼ完全に平滑な光沢表面に仕上がる。更に、錫めっきプリコートに見られるウィスカーの発生もない利点がある。
　尚、低温はんだである錫ビスマス共晶合金に前記適正量の範囲内でニッケルと、ゲルマニウムまたはリンのいずれか１種以上を添加してプリコート皮膜を形成させた電子部品同志（例えば、半導体装置をプリント基板に実装する場合など）を通常の鉛フリーはんだ（例えば、錫銀銅系はんだ、錫銅系はんだ、錫銀系はんだなど）を介して、前記各電子部品のプリコート皮膜にはんだ接合した場合、錫ビスマスはんだプリコート皮膜は１４０~１８０℃程度の低温で溶融するので、前記通常の鉛フリーはんだとの接合温度も若干低く目にして、かつ接合時間が従来法より短くて済むため、電子部品の熱的ダメージが小さいメリットがある。 In order to avoid that, and to achieve a nearly completely smooth glossy surface even when the solder precoat thickness is 10 μm or less, the inventors have conducted various trial and error studies. I found a good thing. For example, pure tin contains a trace amount of nickel of 0.005 to 0.5 mass%, and a trace amount of germanium of 0.001 to 0.1 mass% or phosphorus of 0.003 to 0.1 mass% When a solder precoat film is formed by the method of the present invention using a solder alloy containing tin and the balance tin, it has been found that a precoat film with good smoothness can be obtained.
Besides, eutectic solder such as tin-lead alloy (tin 63 mass%, lead 37 mass%), tin bismuth alloy (tin 42 mass%, bismuth 58 mass%), tin antimony alloy, etc. If a solder added with 0.005 to 0.5 mass% and one or more of 0.001 to 0.1 mass% of germanium or 0.003 to 0.1 mass% of phosphorus is used, the solder Even when the thickness of the precoat film is 20 μm or less, the glossy surface is almost completely smooth. Further, there is an advantage that no whisker is found in the tin plating precoat.
In addition, electronic components composing a pre-coating film by adding nickel and one or more of germanium and phosphorus within a proper amount range to a tin bismuth eutectic alloy which is a low temperature solder (for example, a semiconductor device) When mounting on a printed circuit board, etc.) via ordinary lead-free solder (eg tin-silver-copper solder, tin-copper solder, tin-silver solder, etc.) Since the tin bismuth solder precoat film melts at a low temperature of about 140 to 180 ° C., the bonding temperature with the normal lead-free solder is slightly lower and the bonding time is shorter than that of the conventional method. There is a merit of less thermal damage.
　錫に微量のニッケルを添加する理由は、電子回路のパッドまたはリード表面に錫またははんだ被覆する際に、所謂「銅食われ」（パッドまたはリード表面の銅がはんだに溶け込む現象）を抑制することと、長期に亘り１２０℃以上に累積的に高温暴露された場合にはんだ接合界面近傍に生ずるカーケンダルボイド（マイクロボイド）を抑止し、組み込まれた半導体装置または電子装置の耐衝撃性、耐熱疲労性などの品質信頼性向上化効果を挙げるためである。添加量としては０．００１質量％以下では前記効果が小さく、１質量％以上では溶融時の粘性が高くなり、ブリッジを生じ易いために好ましくない。望ましいニッケルの添加量は０．００５~０．５質量％である。ニッケルの代わりにコバルト、鉄の添加でも効果がる。 The reason for adding a small amount of nickel to tin is to suppress so-called "copper erosion" (a phenomenon in which copper on the pad or lead surface melts into the solder) when tin or solder is coated on the pad or lead surface of the electronic circuit. In addition, it suppresses the Kirkendall voids (microvoids) that occur near the solder joint interface when exposed to a high temperature cumulatively over 120 ° C over a long period of time. This is to improve the quality reliability of the product. When the amount is 0.001% by mass or less, the effect is small, and when the amount is 1% by mass or more, the viscosity at the time of melting becomes high and bridging is likely to occur. A desirable addition amount of nickel is 0.005 to 0.5 mass%. Addition of cobalt or iron instead of nickel is effective.
　また同様に、ゲルマニウムまたはリンを添加する理由は、はんだプリコート皮膜表面の経時的酸化防止とはんだぬれ性の劣化防止が主目的である。これを添加しない場合には、はんだプリコート品を大気中に放置すると、経時的に酸化変色してはんだぬれ性が悪くなる。
　その添加量は少ないと効果が小さく、多過ぎると物理的機械的特性が脆弱になり、割れやすいので好ましくない。従って、望ましい添加量はゲルマニウム０．００１~０．１質量％またはリン０．００３~０．１質量％である。 Similarly, the reason for adding germanium or phosphorus is mainly to prevent the oxidation of the solder precoat film surface over time and the deterioration of solder wettability. In the case where this is not added, if the solder pre-coated product is left in the air, it will undergo oxidative discoloration over time and solder wettability will deteriorate.
If the added amount is small, the effect is small, and if it is too large, the physical mechanical properties become brittle and it is easy to break. Therefore, a desirable addition amount is 0.001 to 0.1% by mass of germanium or 0.003 to 0.1% by mass of phosphorus.
　また、上記以外の本発明の実施形態として、第１ステップで散布する錫またははんだ微粒子の量をむしろ少な目にして、少なくともワークの全てのパッドまたはリードに１個以上錫またははんだ微粒子を搭載させ、第２ステップで前記微粒子をワークのパッドまたはリードに融着させた後、第３ステップとして前記ワークに専用ポンプで高温の有機脂肪酸溶液と、溶融錫液または溶融はんだ液とを、それぞれ吹付け処理を行って、前記パッドまたは前記リード表面に錫またははんだ接合皮膜を形成させると効率的で良い。
　具体的に図で説明すると、図６のようにワーク１を走行させながら移送用ポンプ７によりノズル９から高温の有機脂肪酸溶液６をワーク１のパッドまたはリード表面に吹付けるとともに、同時に移送ポンプ１６によりノズル１７からも溶融錫液または溶融はんだ液１５を吹付け処理行うことにより、前記第２のステップで融着した前記錫またははんだ微粒子を核として、不足している錫またははんだ量を付加補充融合させ、かつ余剰に錫またははんだが付着しないように高温の有機脂肪酸溶液６の吹付けで制御することにより、ワーク１のパッドまたはリードにブリッジのない良好均一な錫またははんだ皮膜形成を効率的に行うことが出来る。
　この場合、前記高温の有機脂肪酸溶液６の吹付けと、前記溶融錫液または溶融はんだ液１５の吹付けは、相互のノズル９と１７とを近接させて、両方の液がオーバーラップするように吹き付けても良いし、あるいはノズル１７を中心にして、その前後にノズル９を１本ずつ少し離して（２０ｍｍ以上）配置して吹付けても良い。
　ノズルの噴出部断面形状は特に限定する必要はないが、生産性を考慮するとワークの走行方向に対して、直角方向を長くした楕円状またはスリット状が効率的で望ましい。
　尚、電子回路基板または電子部品連結体あるいは半導体リードフレームなどが長尺の条帯であれば、連続送りまたは間欠送りして搬送しながら、本発明方法の処理を行うことが出来る。 Further, as an embodiment of the present invention other than the above, the amount of tin or solder fine particles dispersed in the first step is rather small, and at least one tin or solder fine particle is mounted on at least all the pads or leads of the workpiece, After the fine particles are fused to the work pad or lead in the second step, a high temperature organic fatty acid solution and a molten tin solution or a molten solder solution are sprayed to the work with a dedicated pump as the third step. It is efficient that a tin or solder joint film is formed on the surface of the pad or the lead.
Specifically, as shown in FIG. 6, while the workpiece 1 is running as shown in FIG. 6, the transfer pump 7 sprays the high-temperature organic fatty acid solution 6 from the nozzle 9 onto the pad or lead surface of the workpiece 1, and at the same time, the transfer pump 16. By spraying the molten tin solution or the molten solder solution 15 from the nozzle 17, the tin or solder fine particles fused in the second step are used as a core to supplement the missing tin or solder amount. By fusing and controlling by spraying a high-temperature organic fatty acid solution 6 so that excessive tin or solder does not adhere, good uniform tin or solder film formation without a bridge on the pad or lead of the work 1 is efficiently performed. Can be done.
In this case, the spraying of the high-temperature organic fatty acid solution 6 and the spraying of the molten tin solution or the molten solder solution 15 bring the nozzles 9 and 17 close to each other so that both solutions overlap. Alternatively, the nozzles 17 may be sprayed, or the nozzles 9 may be slightly spaced from each other around the nozzle 17 (at least 20 mm) and sprayed.
There is no particular limitation on the cross-sectional shape of the ejection part of the nozzle, but considering productivity, an elliptical shape or a slit shape in which the direction perpendicular to the traveling direction of the workpiece is long is efficient and desirable.
If the electronic circuit board, the electronic component connector, the semiconductor lead frame, or the like is a long strip, the method of the present invention can be performed while being conveyed by continuous feeding or intermittent feeding.
　以上の通り、本発明の第３ステップより、ワークの表面に高温の有機脂肪酸溶液を吹付けて余剰に付着した前記錫またははんだを吹き落し除去し、パッドまたはリードに厚さ２~２０μｍで、かつ厚さのばらつきが±３μｍ以下の均一な錫またははんだ皮膜を形成させることが可能である。 As described above, from the third step of the present invention, a high-temperature organic fatty acid solution is sprayed on the surface of the workpiece to remove the tin or solder adhered excessively, and the pad or lead has a thickness of 2 to 20 μm. In addition, it is possible to form a uniform tin or solder film having a thickness variation of ± 3 μm or less.
　本発明の方法によれば、従来方法では「ブリッジ」が出来るため、良好な回路形成が不可能なパッドまたはリード幅２０~８０μｍ、隣接ピッチ４０~１００μｍの微細狭ピッチ高密度電子回路に、厚さ２~２０μｍの任意の厚さ範囲で、しかも厚さのばらつきを±３μｍ以内に比較的自由に制御しながら、錫またははんだ皮膜を工業的に安定量産可能にする顕著な効果がある。
　しかも、本発明方法により製造した錫またははんだ皮膜を有する電子部品と電子回路基板を使用してはんだ接合して搭載実装した高密度電子装置は、本発明の第２ステップでパッドまたはリードに融着した錫またははんだ層に、第３ステップで高温の有機脂肪酸溶液を吹付けることにより、前記錫またははんだ層を再び溶融状態にして、該層内に存在する微小気泡や空隙、金属酸化物、フラックス反応生成物、その他不純物を除去しながら、かつ余剰の錫またははんだを除去し、必要量の錫またははんだ層を強固にパッドまたはリード表面接合するので、最終的に形成された錫またははんだ層ない及び接合界面には前記従来法（Ａ）や（Ｂ）によく見られるフラックスの沸騰飛散による接合界面及びはんだ層内および接合界面の微小気泡・空隙は全くない。従って、長期高温暴露後のカーケンダルボイド（マイクロボイド）の発生を殆ど皆無に出来る効果がある。特に、酸素濃度２ｐｐｍ以下のはんだを使用すれば、長期高温暴露後のカーケンダルボイドの発生を皆無に出来るので、本発明の錫またははんだ接合部品は長期高温暴露後の耐衝撃破断性が格段に優れている。
　更に、従来法では不可能なパッドまたはリード幅２０~８０μｍ、隣接ピッチ４０~１００μｍの微小・狭ピッチ電子回路に錫またははんだ皮膜を形成することが可能である。
　また、本発明の第３ステップにおいては、仕上がった錫またははんだ皮膜表面に有機脂肪酸の化学吸着保護皮膜（酸化防止皮膜）が必然的にコーティング形成されるので、長期間大気中に保管後も酸化変色し難く、はんだぬれ性の良い状態が保持される。従って、その後の後工程で電子装置組立時のはんだぬれ性が従来法で製造された物より安定して優れている。特に、錫またははんだプリコート皮膜が５μｍ以下の場合は金属間化合物（ＩＭＣ）が表面に露出し、長期保管後に表面酸化するとその上にははんだ付けはできないが、本発明方法で処理した膜厚５μｍ以下のプリコート品の場合はＩＭＣが表面に露出していても長期大気中保管後もはんだ付けが充分出来る。これは、プリコート皮膜表面に有機脂肪酸の化学吸着保護皮膜（酸化防止コーティング皮膜）が形成されている効果と考えられる。
以上の通り、本発明の効果は工業的に極めて価値が高いものである。
これを更に詳しく具体的事例で以下に説明する。 According to the method of the present invention, since a “bridge” can be formed by the conventional method, a pad or lead width of 20 to 80 μm and a fine narrow pitch high density electronic circuit having an adjacent pitch of 40 to 100 μm cannot be formed. There is a remarkable effect that industrially stable mass production of tin or solder coating is possible while controlling the thickness variation within a range of 2 to 20 μm and relatively freely within ± 3 μm.
In addition, the high-density electronic device mounted and mounted by soldering using an electronic circuit board and an electronic component having a tin or solder coating manufactured by the method of the present invention is fused to the pad or lead in the second step of the present invention. The tin or solder layer is sprayed with a high-temperature organic fatty acid solution in the third step so that the tin or solder layer is melted again, and microbubbles or voids, metal oxides, flux existing in the layer. While removing reaction products and other impurities and removing excess tin or solder, the required amount of tin or solder layer is firmly bonded to the pad or lead surface, so there is no finally formed tin or solder layer In addition, in the bonding interface, microbubbles and voids in the bonding interface and in the solder layer and in the bonding interface due to the boiling-off of the flux often seen in the conventional methods (A) and (B). Not at all. Therefore, there is an effect that almost no generation of Kirkendall void (micro void) after long-term high temperature exposure. In particular, if a solder with an oxygen concentration of 2 ppm or less is used, the occurrence of Kirkendall voids after long-term high-temperature exposure can be eliminated, so that the tin or solder joint parts of the present invention have a markedly high impact fracture resistance after long-term high-temperature exposure. Are better.
Furthermore, it is possible to form a tin or solder film on a minute or narrow pitch electronic circuit having a pad or lead width of 20 to 80 μm and an adjacent pitch of 40 to 100 μm, which is impossible with the conventional method.
Further, in the third step of the present invention, a chemical adsorption protective film (antioxidation film) of organic fatty acid is inevitably formed on the surface of the finished tin or solder film, so that it is oxidized even after storage in the atmosphere for a long time. Difficult to discolor and maintains good solder wettability. Therefore, the solder wettability at the time of assembling the electronic device in the subsequent processes is stable and superior to those manufactured by the conventional method. In particular, when the tin or solder precoat film is 5 μm or less, the intermetallic compound (IMC) is exposed on the surface, and if the surface is oxidized after long-term storage, soldering cannot be performed thereon, but the film thickness processed by the method of the present invention is 5 μm. In the case of the following precoat products, even if IMC is exposed on the surface, it can be sufficiently soldered even after long-term storage in the air. This is considered to be an effect that an organic fatty acid chemical adsorption protective film (antioxidant coating film) is formed on the surface of the precoat film.
As described above, the effects of the present invention are extremely valuable industrially.
This will be described in more detail below with specific examples.
本発明方法の第１ステップに使用する錫またははんだの微粒子からなる粉末を細かいメッシュの金網を有する篩または市販の粉末散布装置から、ワークに散布する状態を模式的に示した断面図である。It is sectional drawing which showed typically the state which spreads the powder which consists of a tin or solder fine particle used for the 1st step of this invention method to a workpiece | work from the sieve which has a fine mesh metal net, or a commercially available powder spraying apparatus. 本発明方法の第３ステップの実施形態の１つである吹付け方式の事例として、ワークに高温の有機脂肪酸溶液をノズルで吹付けて、余剰の錫またははんだを除去して、パッドまたはリード表面にはんだ皮膜を形成させる様子を模式的に示した断面図である。As an example of the spraying method which is one of the third step embodiments of the method of the present invention, a hot organic fatty acid solution is sprayed on a workpiece with a nozzle to remove excess tin or solder, and a pad or lead surface It is sectional drawing which showed typically a mode that a solder film was formed in. 本発明方法の第３ステップの実施形態の１つである単純浸漬方式の事例として、高温の有機脂肪酸溶液中に電子回路基板または電子部品連結体（ワーク）を浸漬し、ワークに物理的振動を付与しながら引上げて、余剰の錫またははんだを除去して、パッドまたはリード表面にはんだ皮膜を形成させる様子を模式的に示した断面図である。As an example of the simple dipping method, which is one of the embodiments of the third step of the method of the present invention, an electronic circuit board or a connected electronic component (work) is immersed in a high-temperature organic fatty acid solution, and physical vibration is applied to the work. FIG. 4 is a cross-sectional view schematically showing a state in which a solder film is formed on the surface of a pad or lead by pulling up while applying and removing excess tin or solder. 本発明方法の第３ステップの実施形態の１つである浸漬吹付け方式の事例として、予め高温の有機脂肪酸溶液槽に浸漬したワークを引き上げながら、上部のノズルで高温の有機脂肪酸溶液を吹付けて、余剰の錫またははんだを除去して、パッドまたはリード表面にはんだ皮膜を形成させる様子を模式的に示した断面図である。As an example of the immersion spraying method, which is one of the third step embodiments of the method of the present invention, the high temperature organic fatty acid solution is sprayed by the upper nozzle while pulling up the work previously immersed in the high temperature organic fatty acid solution tank. FIG. 6 is a cross-sectional view schematically showing a state in which excess tin or solder is removed to form a solder film on the pad or lead surface. 本発明方法の第３ステップの実施形態の１つである浸漬ロール吹掛け方式の事例として、予め高温の有機脂肪酸溶液槽に浸漬したワークを、液中に設置された２本のリバースロールに間を通過させ引き上げながら、リバースロールの高速回転によりワークのパッドまたはリード部に該有機脂肪酸溶液を吹掛けて、余剰の錫またははんだを除去して、パッドまたはリード表面にはんだ皮膜を形成させる様子を模式的に示した断面図である。As an example of the immersion roll spraying method which is one of the embodiments of the third step of the method of the present invention, a work previously immersed in a high-temperature organic fatty acid solution tank is placed between two reverse rolls installed in the liquid. The organic fatty acid solution is sprayed onto the pad or lead part of the work by high-speed rotation of the reverse roll while passing the wire up and removing the excess tin or solder to form a solder film on the pad or lead surface. It is sectional drawing shown typically. 本発明の第３ステップの実施形態の１つである有機脂肪酸溶液と溶融錫液または溶融はんだ液の２液吹付け方式の事例として、上層に高温の有機脂肪酸溶液、下層に溶融錫液または溶融はんだ液を配した貯液槽からそれぞれの液を専用ポンプでノズルに給液して、ノズルからそれぞれの液を電子回路基板または電子部品連結体（ワーク）に吹付けて、余剰の錫またははんだを除去して、パッドまたはリード表面にはんだ皮膜を形成させる様子を模式的に示した断面図である。As an example of a two-component spraying method of an organic fatty acid solution and a molten tin solution or a molten solder solution, which is one of the embodiments of the third step of the present invention, a high-temperature organic fatty acid solution is used as the upper layer, and a molten tin solution or molten as the lower layer. Each liquid is supplied to the nozzle from the storage tank in which the solder liquid is arranged with a dedicated pump, and each liquid is sprayed from the nozzle onto the electronic circuit board or electronic component assembly (workpiece), so that excess tin or solder It is sectional drawing which showed typically a mode that a solder | pewter was removed and a solder film was formed in the pad or lead surface. 本発明の第１ステップの実施形態の１つである錫またははんだ微粒子からなる粉体散布事例として、粉体散布装置からワークに前記粉体散布している様子を模式的に示した断面図である。1 is a cross-sectional view schematically showing a state where the powder is sprayed from a powder spraying device to a workpiece as a powder spraying example made of tin or solder fine particles, which is one of the first step embodiments of the present invention. is there. 本発明の第２ステップの実施形態の１つである錫またははんだ微粒子からなる粉体をワークのパッドまたはリードに融着させた状態の事例として、模式的にワークの断面状態を示した断面図である。Sectional drawing which showed typically the cross-sectional state of the workpiece | work as an example of the state which fuse | melted the powder which consists of the tin or solder fine particle which is one of the 2nd step embodiment of this invention to the pad or lead of the workpiece | work. It is. 本発明の方法及び装置において、電子回路基板または電子部品連結体の搬送に使用するプログラム式自動３次元移動装置のロボットアーム部分と、ワークを取付けた治具（枠状専用ホルダー）部分の事例を模式的に示した断面図である。In the method and apparatus of the present invention, examples of a robot arm part of a programmable automatic three-dimensional movement device used for transporting an electronic circuit board or an electronic component assembly and a jig (frame-shaped dedicated holder) part to which a workpiece is attached are shown. It is sectional drawing shown typically. 本発明実施例および比較例で製造したはんだプリコート皮膜の加熱エージング（１５０℃、２４０時間）後の断面形態で、ａ）は比較例２のプリコート皮膜の状態を模式的に示した図で、ｂ）は比較例２のプリコート皮膜の一部分の断面写真事例、同様にｃ）は実施例７のプリコート皮膜の状態を模式的に示した図で、ｄ）は実施例７のプリコート皮膜の一部分の断面写真事例を示したものであるFIG. 4 is a cross-sectional view after heat aging (150 ° C., 240 hours) of the solder precoat film produced in the examples of the present invention and the comparative example, and a) schematically shows the state of the precoat film of Comparative Example 2; ) Is a cross-sectional photographic example of a part of the precoat film of Comparative Example 2, similarly c) is a diagram schematically showing the state of the precoat film of Example 7, and d) is a cross section of a part of the precoat film of Example 7. This is an example of a photograph
　本発明の実施例と従来方法との比較例について以下に述べる。
　先ず、共通の試供試料として、電子回路基板は以下の２種類を用いた。
　試料１：外形寸法１０ｍｍ×１０ｍｍ×０．８ｍｍの中央を中心に左右にリード幅２０μｍ、リード長さ６ｍｍ、隣接ピッチ５０μｍで描かれたリード５０本を１単位にしたテスト回路が２０ｍｍピッチで２列Ｘ４ユニット、同様に、リード幅４０μｍ、リード長さ６ｍｍ、隣接ピッチ６０μｍで描かれたリード５０本を１単位にしたテスト回路が２０ｍｍピッチで２列Ｘ４ユニット配列された電子回路基板。
　尚、前記リード部以外のワーク表面には全てソルダーレジストが塗布され、ソルダーレジスト膜とリート表面の段差は約１０μソルダーレジスト膜の方が高くなっている。
　試料２：外形寸法１０ｍｍ×１０ｍｍ×１．０ｍｍ、電極パッド数３０４、パッド径０．１ｍｍφ、はんだレジスト保護皮膜で覆われていないパッド径０．０８ｍｍφ、パッド間ピッチ０．１５ｍｍのＢＧＡが２０ｍｍピッチで２列各４個配列された電子回路基板。尚、試料１と同様に、ソルダーレジスト膜とリート表面の段差は約１０μソルダーレジスト膜の方が高くなっている。
　また、はんだ中の酸素濃度を下げた低酸素はんだ合金の作製方法は、銀２．５質量％、銅５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、残部錫からなる鉛フリーはんだ合金を予め溶融させた溶融はんだ液と、パルミチン酸３０重量％と残部エステル合成からなる液温２６０℃の有機脂肪酸溶液とを撹拌器内に循環給液して、激しく撹拌して溶融はんだ内部に存在する金属酸化物、及び不純物をパルミチン酸のケン化作用を利用して、前記パルミチン酸溶液中に取り込ませて、撹拌混合液を貯槽に戻し、溶融はんだ液とパルミチン酸溶液の比重差を利用して両液を分離しながら、これを酸素濃度が１ｐｐｍ以下になるまで繰り返し循環処理して精製作成した。これを母合金として、酸素濃度が２、５、１０ｐｐｍになるように、この母合金に上記精製処理前の酸素濃度既知（１２０ｐｐｍ）の同金属組成のはんだ合金を加えて溶融し、それぞれの酸素濃度のはんだ合金を作製し、以下の比較例（従来方法）と実施例の評価試験に供した。 A comparative example of the embodiment of the present invention and the conventional method will be described below.
First, the following two types of electronic circuit boards were used as common sample samples.
Sample 1: A test circuit using 50 leads drawn as a unit with a lead width of 20 μm, a lead length of 6 mm, and an adjacent pitch of 50 μm centered on the center of the outer dimensions of 10 mm × 10 mm × 0.8 mm is 2 at 20 mm pitch. Similarly, an electronic circuit board in which test circuits each having 50 leads drawn in a unit of 50 rows drawn with a lead width of 40 μm, a lead length of 6 mm, and an adjacent pitch of 60 μm are arranged in two rows of X4 units at a pitch of 20 mm.
Note that a solder resist is applied to the entire work surface other than the lead portion, and the step difference between the solder resist film and the REIT surface is higher in the approximately 10 μ solder resist film.
Sample 2: BGA with outer dimensions of 10 mm × 10 mm × 1.0 mm, number of electrode pads 304, pad diameter of 0.1 mmφ, pad diameter of 0.08 mmφ not covered with solder resist protective film, and pad pitch of 0.15 mm is 20 mm pitch Electronic circuit boards arranged in two rows of 4 each. As in the case of Sample 1, the step difference between the solder resist film and the REIT surface is higher in the approximately 10 μ solder resist film.
Also, a method for producing a low-oxygen solder alloy with a reduced oxygen concentration in the solder is 2.5% by mass of silver, 5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, and lead consisting of the balance tin. A molten solder solution obtained by pre-melting a free solder alloy and an organic fatty acid solution having a liquid temperature of 260 ° C. composed of 30% by weight of palmitic acid and the remaining ester are circulated in a stirrer and vigorously stirred to melt the solder. Utilizing the saponification action of palmitic acid, metal oxides and impurities existing inside are taken into the palmitic acid solution, the stirred mixed solution is returned to the storage tank, and the specific gravity difference between the molten solder solution and the palmitic acid solution While separating both liquids using the above, this was repeatedly circulated until the oxygen concentration was 1 ppm or less, and purified. Using this as a mother alloy, a solder alloy of the same metal composition with a known oxygen concentration (120 ppm) before the refining treatment was added to the mother alloy so that the oxygen concentration would be 2, 5, 10 ppm, and then melted. Concentration solder alloys were prepared and used for evaluation tests of the following comparative examples (conventional methods) and examples.
［比較例１］
　銀２．５質量％、銅０．５質量％、残部錫からなる組成の鉛フリーはんだ合金をそのまま溶融した浴温２６０℃のはんだ浴に、予めパット部にロジン系フラックスが塗布されている試料１及び２を２秒間浸漬してパッド部にはんだ付け処理した後、通常のホットエアーレベラーで温度３５０℃、圧力（圧力計ゲージ）０．２ＭＰａで処理した。 [Comparative Example 1]
A sample in which a rosin flux is applied in advance to a pad part in a solder bath having a bath temperature of 260 ° C., in which a lead-free solder alloy having a composition of 2.5% by mass of silver, 0.5% by mass of copper, and the balance of tin is melted as it is. After immersing 1 and 2 for 2 seconds and soldering to the pad part, it processed with the temperature of 350 degreeC and the pressure (pressure gauge gauge) 0.2MPa with the normal hot air leveler.
［比較例２］
　市販の銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、残部錫からなる鉛フリーはんだ合金をそのまま溶融した浴温２６５℃のはんだ浴に、予めパッド部にロジン系フラックスが塗布されている試料１及び２を３秒間浸漬してパッド部にはんだ付け処理した後、通常のホットエアーレベラーで温度３５０℃、圧力（圧力計ゲージ）０．２ＭＰａで処理した。 [Comparative Example 2]
In a solder bath with a bath temperature of 265 ° C., a molten lead-free solder alloy consisting of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, and the balance tin is used. Then, after immersing Samples 1 and 2 in which the rosin flux was previously applied to the pad part for 3 seconds and soldering the pad part, the temperature was 350 ° C. and the pressure (pressure gauge gauge) 0. 0 with a normal hot air leveler. Processed at 2 MPa.
［比較例３］
　銀２．５質量％、銅０．５質量％、残部錫からなる鉛フリーはんだ合金の粉末をフラックス成分などと混練した市販のクリームはんだ（ソルダーペースト）を用いて、試料１及び２に通常のシルクスクリーン印刷法でパッド部にソルダーペーストを塗布した後、該試料１，２をピーク温度３５０℃の通常のリフロー炉中を通過させて、パッドにはんだ被膜を形成させた。 [Comparative Example 3]
Using commercially available cream solder (solder paste) obtained by kneading a powder of lead-free solder alloy composed of 2.5% by mass of silver, 0.5% by mass of copper and the balance tin with a flux component or the like, After the solder paste was applied to the pad portion by a silk screen printing method, the samples 1 and 2 were passed through a normal reflow furnace having a peak temperature of 350 ° C. to form a solder film on the pad.
［比較例４］
　銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度１０ｐｐｍ、残部錫からなる組成に調整した鉛フリーはんだ合金を溶融した浴温２６０℃の溶融はんだ浴に、従来方法、即ち、予めパッド部にロジン系フラックスが塗布されている試料１及び２を２秒間浸漬してパッド部にはんだ付け処理した後、通常のホットエアーレベラーで温度３５０℃、圧力（圧力計ゲージ）０．２ＭＰａで処理した。 [Comparative Example 4]
Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 10 ppm of oxygen, and the balance tin. After immersing Samples 1 and 2 in which the rosin flux was previously applied to the pad part for 2 seconds in the molten solder bath at 0 ° C. for 2 seconds and soldering to the pad part, the temperature was measured with a normal hot air leveler. It processed at 350 degreeC and the pressure (pressure gauge gauge) 0.2MPa.
［比較例５］
　銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度２ｐｐｍ、残部錫からなる組成に調整した鉛フリーはんだ合金を溶融した浴温２６０℃の溶融はんだ浴に、従来方法、即ち、予めパッド部にロジン系フラックスが塗布されている試料１及び２を２秒間浸漬してパッド部にはんだ付け処理した後、通常のホットエアーレベラーで温度３５０℃、圧力（圧力計ゲージ）０．２ＭＰａで処理した。 [Comparative Example 5]
Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin. After immersing Samples 1 and 2 in which the rosin flux was previously applied to the pad part for 2 seconds in the molten solder bath at 0 ° C. for 2 seconds and soldering to the pad part, the temperature was measured with a normal hot air leveler. It processed at 350 degreeC and the pressure (pressure gauge gauge) 0.2MPa.
［比較例６］
　銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度２ｐｐｍ、残部錫からなる組成に調整した鉛フリーはんだ合金を溶融した浴温２６０℃の溶融はんだ浴に、従来方法、即ち、予めパッド部にロジン系フラックスが塗布されている試料１及び２を２秒間浸漬してパッド部にはんだ付け処理した後、液温２３０℃のグリセリンを吹き付けて余剰のはんだを吹き落とすホットリキッドレベラー処理を行った。 [Comparative Example 6]
Bath temperature 260 obtained by melting a lead-free solder alloy adjusted to a composition comprising 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin. After immersing samples 1 and 2 in which the rosin flux was previously applied to the pad portion for 2 seconds in the molten solder bath at 0 ° C. and soldering the pad portion, glycerin at a liquid temperature of 230 ° C. was added. The hot liquid leveler process which sprays and blows off the excess solder was performed.
　試料１及び２について、予め液温１２０℃のパルミチン酸１０質量％、残部エステル合成油からなる溶液に浸漬して、パッド及びリードの表面を清浄化するとともに清浄化された表面にパルミチン酸の保護膜を形成させた後、図１のような粉末散布装置で粒子径１~２０μｍφの銀２．５質量％、銅０．５質量％、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記粉体の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約３０倍量を散布した。
　次に２６０℃に過熱されたホットプレート上に各試料（ワーク）を載せて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、図４のような浸漬吹付け装置中の液温２６０℃の前記組成のパルミチン酸溶液にワークを浸漬して徐々に引き上げながら、前記高温のパルミチン酸溶液を流速２．０ｍ／秒で吹付けて、パッド及びリードのはんだ皮膜の仕上がり厚さが５μｍになるように、余剰のはんだを吹き落として除去した。 Samples 1 and 2 were preliminarily immersed in a solution consisting of 10% by weight palmitic acid at a liquid temperature of 120 ° C. and the remaining ester synthetic oil to clean the surfaces of the pads and leads and to protect palmitic acid on the cleaned surfaces. After the film is formed, the above-mentioned pad is sprayed from above with solder fine particles composed of 2.5% by mass of silver having a particle diameter of 1 to 20 μmφ, 0.5% by mass of copper, and the remaining tin with a powder spraying device as shown in FIG. A sufficient amount of the solder fine particles was mounted on the lead surface. At this time, the amount of the powder sprayed was about 30 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads. The hot palmitic acid solution was sprayed at a flow rate of 2.0 m / sec while immersing the workpiece in a palmitic acid solution having the above composition at a liquid temperature of 260 ° C. in such an immersion spraying apparatus, and the pad and Excess solder was blown off and removed so that the finished thickness of the lead solder film was 5 μm.
　試料１及び２について、予めパルミチン酸ニッケル５質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をスプレーで噴霧して、パッド及びリードの表面に塗布、乾燥させた後、図１のような粉末散布装置で粒子径１~１０μｍφの銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記はんだ微粒子の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約５０倍量を散布した。
　次に各試料（ワーク）を温度プロファイル上の最高実質温度２６０℃のリフロー炉に搬入して炉中を通過させて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、図４のような浸漬吹付け装置中の液温２６０℃のパルミチン酸１０質量％、残部エステル合成油からなるパルミチン酸溶液にワークを浸漬して徐々に引き上げながら、前記高温のパルミチン酸溶液を流速１．１ｍ／秒で吹付けて、パッド及びリードのはんだ皮膜の仕上がり厚さが１０μｍになるように、余剰のはんだを吹き落として除去した。 About samples 1 and 2, after spraying a flux dilution liquid consisting of 5% by mass of nickel palmitate, 45% by mass of normal rosin flux, and the remaining solvent by spraying, and applying and drying on the surface of the pad and lead, Solder fine particles composed of 2.5% by mass of silver having a particle diameter of 1 to 10 μm, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, and the balance of tin with a powder spreader as shown in FIG. A sufficient amount of the solder fine particles were mounted on the pad and lead surfaces by spraying from above. At this time, the amount of the solder fine particles sprayed was about 50 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (workpiece) is carried into a reflow furnace having a maximum real temperature of 260 ° C. on the temperature profile and passed through the furnace to melt the solder fine particles mounted on the work, so that the pads and leads After the workpiece is immersed in a palmitic acid solution consisting of 10% by mass of palmitic acid at a liquid temperature of 260 ° C. in the immersion spraying apparatus as shown in FIG. The hot palmitic acid solution was sprayed at a flow rate of 1.1 m / sec, and excess solder was blown off and removed so that the finished thickness of the solder film on the pads and leads was 10 μm.
　試料１及び２について、予めパルミチン酸ニッケル５質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をスプレーで噴霧して、パッド及びリードの表面に塗布、乾燥させた後、図１のような粉末散布装置で粒子径１~１０μｍφの銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度１０ｐｐｍ、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記はんだ微粒子の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約１００倍量を散布した。
　次に各試料（ワーク）を温度プロファイル上の最高実質温度２６０℃のリフロー炉に搬入して炉中を通過させて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、図４のような浸漬吹付け装置中の液温２６０℃のパルミチン酸１０質量％、残部エステル合成油からなるパルミチン酸溶液にワークを浸漬して徐々に引き上げながら、前記高温のパルミチン酸溶液を流速２．１ｍ／秒で吹付けて、パッド及びリードのはんだ被膜の仕上がり厚さが５μｍになるように、余剰のはんだを吹き落として除去した。 About samples 1 and 2, after spraying a flux dilution liquid consisting of 5% by mass of nickel palmitate, 45% by mass of normal rosin flux, and the remaining solvent by spraying, and applying and drying on the surface of the pad and lead, From a powder spraying device as shown in FIG. A sufficient amount of the solder fine particles were mounted on the pad and the lead surface by spraying the solder fine particles to be formed from above. At this time, the solder fine particles were dispersed in an amount of about 100 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (workpiece) is carried into a reflow furnace having a maximum real temperature of 260 ° C. on the temperature profile and passed through the furnace to melt the solder fine particles mounted on the work, so that the pads and leads After the workpiece is immersed in a palmitic acid solution consisting of 10% by mass of palmitic acid at a liquid temperature of 260 ° C. in the immersion spraying apparatus as shown in FIG. A hot palmitic acid solution was sprayed at a flow rate of 2.1 m / sec, and excess solder was blown off and removed so that the finished thickness of the solder coating on the pads and leads was 5 μm.
　試料１及び２について、予めステアリン酸ニッケル９質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をローラーでパッド及びリードの表面に塗布、乾燥させた後、図１のような粉末散布装置で粒子径１~１０μｍφの銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度２ｐｐｍ、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記はんだ微粒子の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約２０倍量を散布した。
　次に２６０℃に過熱されたホットプレート上に各試料（ワーク）を載せて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、浴温２５０℃の銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度２ｐｐｍ、残部錫からなるはんだ浴にワークを浸漬して、充分な量のはんだを前記融着したパッド及びリードにはんだ層に融合上積みした後、図３のような装置のノズルから液温２５０℃のステアリン酸１５質量％、残部エステル合成油からなる溶液を流速２．０ｍ／秒で吹付けて、パッド及びリードのはんだ皮膜の仕上がり厚さが５μｍになるように、余剰のはんだを吹き落として除去した。 For Samples 1 and 2, a flux dilution solution consisting of 9% by weight of nickel stearate, 45% by weight of ordinary rosin flux, and the remaining solvent was applied to the surfaces of the pads and leads with a roller and dried, as shown in FIG. Solder powder consisting of 2.5% by mass of silver having a particle diameter of 1 to 10 μm, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the balance tin with a simple powder spraying device A sufficient amount of the solder fine particles were mounted on the pad and lead surfaces by spraying from above. At this time, the amount of the solder fine particles sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads. A sufficient amount is obtained by immersing the workpiece in a solder bath composed of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 2 ppm of oxygen, and the remainder of tin. After the solder and the solder are fused and stacked on the solder layer, a solution of 15 mass% stearic acid at a liquid temperature of 250 ° C. and the remaining ester synthetic oil is flowed from the nozzle of the apparatus as shown in FIG. By spraying at 0 m / sec, excess solder was blown off and removed so that the finished thickness of the solder film on the pads and leads was 5 μm.
　試料１及び２について、予めステアリン酸ニッケル９質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をローラーでパッド及びリードの表面に塗布、乾燥させた後、図１のような粉体散布装置で粒子径１~１０μｍφの銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度１ｐｐｍ、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記はんだ微粒子の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約２０倍量を散布した。
　次に２６０℃に過熱されたホットプレート上に各試料（ワーク）を載せて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、浴温２５０℃の銀２．５質量％、銅０．５質量％、ニッケル０．０１質量％、ゲルマニウム０．００５質量％、酸素濃度１ｐｐｍ、残部錫からなる溶融はんだ浴にワークを浸漬して、充分な量のはんだを前記融着したパッド及びリードにはんだ層に融合上積みした後、図３のような装置のノズルから液温２５０℃のステアリン酸１０質量％、残部エステル合成油からなる溶液を流速２．０ｍ／秒で吹付けて、パッド及びリードのはんだ皮膜の仕上がり厚さが５μｍになるように、余剰のはんだを吹き落として除去した。 For Samples 1 and 2, a flux dilution solution consisting of 9% by weight of nickel stearate, 45% by weight of ordinary rosin flux, and the remaining solvent was applied to the surfaces of the pads and leads with a roller and dried, as shown in FIG. Solder fine particles consisting of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 1 ppm of oxygen concentration, and 1% of the remaining tin with a particle size of 1 to 10 μmφ Was sprayed from above to mount a sufficient amount of the solder fine particles on the pad and lead surface. At this time, the amount of the solder fine particles sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads. The workpiece is immersed in a molten solder bath composed of 2.5% by mass of silver, 0.5% by mass of copper, 0.01% by mass of nickel, 0.005% by mass of germanium, 1 ppm of oxygen, and the balance of tin. After the amount of solder is fused and stacked on the soldered pad and lead, a solution of 10 mass% stearic acid at a liquid temperature of 250 ° C. and the remaining ester synthetic oil is flowed from the nozzle of the apparatus as shown in FIG. The excess solder was blown off and removed so that the final thickness of the solder film of the pads and leads was 5 μm.
　試料１及び２について、予めパルミチン酸ニッケル５質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をスプレーで噴霧してパッド及びリードの表面に塗布、乾燥させた後、図１のような粉末散布装置で粒子径１~１５μｍφのニッケル０１質量％、ゲルマニウム０．００５質量％、酸素濃度２ｐｐｍ、残部錫からなるはんだ微粒子を上部から散布して前記パッド及びリード表面上に充分な量の前記はんだ微粒子を搭載した。このときの前記はんだ微粒子の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約６０倍量を散布した。
　次に２６０℃に過熱されたホットプレート上に各試料（ワーク）を載せて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、図４のような装置のノズルから液温２５０℃のパルミチン酸１０質量％、残部エステル合成油からなる溶液を流速１．８ｍ／秒で吹付けて、パッド及びリードのはんだ皮膜の仕上がり厚さが６μｍになるように、余剰のはんだを吹き落として除去した。 Samples 1 and 2 were sprayed with 5% by mass of nickel palmitate, 45% by mass of normal rosin-based flux, and the remainder of the solvent by spraying on the surfaces of the pads and leads, and dried. With a powder spraying device such as No. 1, 01% by weight of nickel with a particle size of 1 to 15 μmφ, 0.005% by weight of germanium, oxygen concentration of 2 ppm, the remaining solder tin consisting of tin is sprayed from the top, and it is sufficient on the pad and lead surface An appropriate amount of the solder fine particles was mounted. At this time, the amount of the solder fine particles sprayed was about 60 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads. A solution consisting of 10% by mass of palmitic acid having a liquid temperature of 250 ° C. and the remaining ester synthetic oil is sprayed at a flow rate of 1.8 m / sec from a nozzle of such an apparatus, and the finished thickness of the solder film of the pads and leads becomes 6 μm. Thus, excess solder was blown off and removed.
　試料１及び２について、予めパルミチン酸ニッケル５質量％、通常のロジン系フラックス４５質量％、残部溶媒からなるフラックス希釈液をスプレーで噴霧してパッド及びリードの表面に塗布、乾燥させた後、図１のような粉末散布装置で粒子径１~１０μｍφの錫４２質量％、ビスマス５８質量％、酸素濃度３ｐｐｍからなる錫ビスマス共晶合金に、ニッケル０．０７質量％、ゲルマニウム０．００５質量％を添加したはんだ微粒子を上部から散布して前記パッド及びリード表面上に前記はんだ微粒子を搭載した。このときの前記粉体の散布量は全ての開口部が溶融はんだで完全に充填される理論容量値の約２０倍量を散布した。
　次に２６０℃に過熱されたホットプレート上に各試料（ワーク）を載せて、前記ワーク上に搭載された前記はんだ微粒子を溶融させて、前記パッド及びリードに融着させた後、図６のような装置のノズル９から液温２６０℃のパルミチン酸１０質量％、残部エステル合成油からなる溶液を流速０．８ｍ／秒で吹付け、次にノズル１７から錫４２質量％、ビスマス５８質量％、酸素濃度３ｐｐｍからなる錫ビスマス共晶合金に、ニッケル０．０７質量％、ゲルマニウム０．００５質量％を添加した溶融はんだを吹付け、更にその後方に設置された別のノズル９で再び液温２６０℃のパルミチン酸１０質量％、残部エステル合成油からなる溶液を流速１．８ｍ／秒で吹付け、パッド及びリードのはんだ皮膜の仕上がり厚さが６μｍになるように前記はんだ皮膜を形成させた。 Samples 1 and 2 were sprayed with 5% by mass of nickel palmitate, 45% by mass of normal rosin-based flux, and the remainder of the solvent by spraying on the surfaces of the pads and leads, and dried. 1 to 10 μmφ tin 42 mass%, bismuth 58 mass%, oxygen concentration 3ppm tin tin bismuth eutectic alloy 0.07 mass% nickel, 0.005 mass% germanium The added solder fine particles were dispersed from above and the solder fine particles were mounted on the pad and lead surfaces. At this time, the amount of the powder sprayed was about 20 times the theoretical capacity value at which all openings were completely filled with molten solder.
Next, each sample (work) is placed on a hot plate heated to 260 ° C., and the solder fine particles mounted on the work are melted and fused to the pads and leads. From the nozzle 9 of such an apparatus, a solution consisting of 10% by mass of palmitic acid having a liquid temperature of 260 ° C. and the remaining ester synthetic oil was sprayed at a flow rate of 0.8 m / second, and then 42% by mass of tin and 58% by mass of bismuth from the nozzle 17. Then, molten solder added with 0.07% by mass of nickel and 0.005% by mass of germanium is sprayed onto a tin-bismuth eutectic alloy having an oxygen concentration of 3 ppm, and the liquid temperature is again returned by another nozzle 9 installed behind the molten solder. A solution composed of 10% by mass of palmitic acid at 260 ° C. and the remaining ester synthetic oil was sprayed at a flow rate of 1.8 m / sec, so that the finished thickness of the solder film on the pads and leads was 6 μm. To form a solder film.
　評価試験は、外観については、顕微鏡（Ｘ２０~１００倍）でブリッジやミッシング（はんだ不着）の有無を観察した。
　上記各比較例および実施例の鉛フリーはんだ中の銅濃度、不純物濃度については、比較例１~６、実施例１~７の各試作実験に先立ち使用直前のはんだをサンプリングし、最新のＴＯＦ−ＳＩＭＳ分析装置により表面から深さ１０μｍの内部までの酸素濃度を測定した。
　また、実施例１~７の加熱エージング後の半導体装置の半田接合部のボイド観察試料および耐衝撃性試験試料の作成には、試料２に対応するバーンイン試験用プリント回路基板を使用して、実施例１~７の各試料２を搭載してリフロー炉ではんだ接合して評価用試料として評価試験に供した。比較例１~６については、ミッシングが多過ぎて評価不能であった。
　はんだ接合部界面付近のボイド有無の評価方法は、評価試験用試料を常態と、恒温加熱炉に１５０℃、２４０時間放置して加熱エージング加速試験後について、それぞれ半田接合部断面を研磨して、走査電子顕微鏡（ＳＥＭ）及びＸ線マイクロアナライザー（ＥＰＭＡ）により、該半田接合部付近のマイクロボイドの数と大きさを観察ならびに分析し比較した。
　また、同一条件下で同時に加熱エージング加速試験した上記実施例１~７の各試料２のＢＧＡ側のはんだ接合部界面付近のボイド有無の評価方法として、評価試験用試料を常態と、恒温加熱炉に１５０℃、２４０時間放置して加熱エージング加速試験後について、それぞれ半田接合部断面を研磨して、走査電子顕微鏡（ＳＥＭ）及びＸ線マイクロアナライザー（ＥＰＭＡ）により、該半田接合部付近のマイクロボイドの数と大きさを観察ならびに分析し比較した。
一方、同一条件下で同時に加熱エージング加速試験をした上記実施例１~７の試料を、市販のＢＧＡ等電子デバイス部品用全自動落下試験装置を用い、ＪＥＤＥＣ（Ｊｏｉｎｔ　Ｅｌｅｃｔｒｏｎ　Ｄｅｖｉｃｅ　Ｅｎｇｉｎｅｅｒｉｎｇ　Ｃｏｕｎｃｉｌ）規格のＮｏ．２２−Ｂ１１１に準じて高さ１０００ｍｍから約１３００Ｇで繰り返し落下させ、その都度各試験試料の導通試験を行い、導通不良が発生するまでの落下試験回数を調べた。（表２） In the evaluation test, the appearance was observed with a microscope (X20 to 100 times) for the presence of bridges and missing (non-soldering).
Regarding the copper concentration and impurity concentration in the lead-free solders of the above comparative examples and examples, the solders immediately before use were sampled prior to each prototype experiment of comparative examples 1 to 6 and examples 1 to 7, and the latest TOF- The oxygen concentration from the surface to the inside of a depth of 10 μm was measured by a SIMS analyzer.
In addition, a void observation sample and an impact resistance test sample of the solder joint portion of the semiconductor device after heat aging in Examples 1 to 7 were prepared using a printed circuit board for burn-in test corresponding to Sample 2. Each sample 2 of Examples 1 to 7 was mounted and soldered in a reflow furnace, and subjected to an evaluation test as an evaluation sample. In Comparative Examples 1 to 6, evaluation was not possible due to excessive missing.
The evaluation method for the presence or absence of voids in the vicinity of the solder joint interface is that the sample for the evaluation test is in a normal state and left in a constant temperature heating furnace at 150 ° C. for 240 hours, and after the heating aging acceleration test, the solder joint cross section is polished, Using a scanning electron microscope (SEM) and an X-ray microanalyzer (EPMA), the number and size of microvoids near the solder joint were observed, analyzed, and compared.
In addition, as a method for evaluating the presence or absence of voids in the vicinity of the solder joint interface on the BGA side of each of the samples 2 of Examples 1 to 7 that were simultaneously subjected to the heat aging acceleration test under the same conditions, the evaluation test sample was used as a normal state and a constant-temperature heating furnace. After the heat aging acceleration test after standing at 150 ° C. for 240 hours, the cross section of the solder joint is polished, and the micro void near the solder joint is observed by a scanning electron microscope (SEM) and an X-ray microanalyzer (EPMA). The number and size of these were observed, analyzed and compared.
On the other hand, the samples of Examples 1 to 7 that were subjected to the accelerated heat aging test under the same conditions at the same time were subjected to JEDEC (Joint Electron Engineering Engineering) standard No. using a fully automatic drop test apparatus for electronic device parts such as a BGA. . According to 22-B111, the test piece was repeatedly dropped from a height of 1000 mm to about 1300 G, and a continuity test of each test sample was performed each time, and the number of drop tests until a continuity failure occurred was examined. (Table 2)
　その結果は下記［表１］の通り、特に、微細回路である試料１及び２におけるはんだ形成部の外観検査において、実施例１~７と、比較例１~６との間にはいずれにも明確な有意差があり、比較例１~６ではほんの一部のパッドまたはリードにはんだが付くものもあるが、殆どはんだが付着しない、所謂「ミッシング（はんだ未着）」が多発した。
　一方、はんだ膜厚のばらつきは、本発明方法である実施例１~７が±２μｍの範囲に入っている。これに対して比較例１~６はいずれもミッシングが多く、局部的に付着している部分を測定すると１~１４μｍと厚さのばらつきが大きく不均一であることが判った。 The results are as shown in [Table 1] below, and in particular, between the examples 1 to 7 and the comparative examples 1 to 6 in the appearance inspection of the solder formation part in the samples 1 and 2 which are fine circuits. There was a clear significant difference. In Comparative Examples 1 to 6, some of the pads or leads had solder attached thereto, but so-called “missing (solder unattached)” in which almost no solder adhered thereto occurred frequently.
On the other hand, the variation in the solder film thickness is in the range of ± 2 μm in Examples 1 to 7, which are the method of the present invention. On the other hand, all of Comparative Examples 1 to 6 had a large amount of missing, and it was found that the variation in thickness was 1 to 14 μm and non-uniformity when the locally attached portion was measured.
　更に、使用したはんだ中の酸素濃度とカーケンダルボイド（マイクロボイド）の関係について、比較例（局部的にはんだが付いた部分のみ観測）、実施例とも常態においては、比較例及び実施例とも全くマイクロボイドもないことを確認した上で、加熱エージング（１５０℃、２４０時間）を行ったが、表２の通り、本発明である実施例では、酸素濃度が高いはんだを使用した実施例１、２ではカーケンダルボイドの発生が若干見られたが、酸素濃度を５ｐｐｍ以下に調整したはんだを使用した実施例４~７では、明らかに溶融はんだの粘性が一段と低くなり、所謂「はんだ切れ」が良くなり、カーケンダルボイドの発生は激減する。酸素濃度を２ｐｐｍ以下にした実施例５~７では加熱エージング後のカーケンダルボイド発生を皆無に出来ることが検証された。物理化学的な物性上の変曲点（臨界点）が酸素濃度５ｐｐｍ付近にあると推定される。
　これに対して、比較例１~６（局部的にはんだが付いた部分のみ観測）の場合、加熱エージング（１５０℃、２４０時間）後の接合界面にはかなり大きいカーケンダルボイドが多数（接合部断面長さ０．２ｍｍ当り２００~３００個）見られた。
　また、耐衝撃性試験結果は表２の通り、比較例１~６ははんだ不着多発のため測定不能であったが、実施例１~７とも２０回でも全く不良を発生しないことが確認された。尚、衝撃試験は２０回で一応打ち切ったので、それ以上どこまで正常性を保持できるかは未確認である。その理由は２０回も持てば実用上、信頼性として充分なことに因る。 Furthermore, with respect to the relationship between the oxygen concentration in the solder used and the Kirkendall void (micro void), the comparative example (observed only on the part where the solder was locally attached), the example and the normal state, both the comparative example and the example were completely After confirming that there were no microvoids, heat aging (150 ° C., 240 hours) was performed. As shown in Table 2, in the example of the present invention, Example 1 using a solder having a high oxygen concentration, In Example 4 to 7 in which solder with an oxygen concentration adjusted to 5 ppm or less was used, the viscosity of the molten solder was clearly lowered further, and so-called “solder out” occurred. It becomes better and the occurrence of Kirkendall void is drastically reduced. In Examples 5 to 7 in which the oxygen concentration was 2 ppm or less, it was verified that generation of Kirkendall voids after heat aging could be eliminated. It is presumed that the inflection point (critical point) in physical and chemical properties is in the vicinity of an oxygen concentration of 5 ppm.
On the other hand, in Comparative Examples 1 to 6 (observed only on the part where solder was locally attached), there were a lot of fairly large Kirkendall voids at the joint interface after heat aging (150 ° C., 240 hours) (joint part). 200 to 300 pieces per 0.2 mm cross-sectional length).
Further, as shown in Table 2, the results of the impact resistance test were not able to be measured in Comparative Examples 1 to 6 due to frequent solder non-bonding, but it was confirmed that no failure occurred even in Examples 1 to 7 even 20 times. . In addition, since the impact test was temporarily stopped after 20 times, it has not been confirmed to what extent the normality can be maintained. The reason is that if it has 20 times, it is practically sufficient for reliability.
　尚、前記実施例では、対象として電子回路基板としてＢＧＡとそれに対応するバーンインテスト用プリント回路基板を使用したが、それ以外の電子回路基板でも同様の効果が得られることは容易に類推できるし、超ミニトランジスタ、超ミニダイオード、ミニコンデンサなどの微小な電子部品は多列多数個取りでマトリックス状に連結して配列したリードフレーム条帯、短冊などの電子部品連結体、あるいは線棒または板状保持体に整列配列した電子部品配列体に本発明の方法ではんだ被膜またははんだプリコート被膜を形成させても、同じ効果が得られることは容易に類推される。従って、これらは本発明の範囲内である。
　また、コイル状に巻いた微小な電子部品は多列多数個取りでマトリックス状に連結して配列したリードフレーム条帯は、本発明方法ではその移動処理と連続送りまたは間欠送りなどして処理することが出来る。 In addition, in the said Example, although BGA and the printed circuit board for a burn-in test corresponding to it as an electronic circuit board were used as object, it can be easily analogized that the same effect is acquired also in other electronic circuit boards, Small electronic components such as ultra-mini transistors, ultra-mini diodes, mini capacitors, etc. are connected to each other in a matrix with multiple rows and rows of electronic components, such as lead frame strips and strips, or wire rods or plates. It can be easily inferred that the same effect can be obtained even if a solder coating or a solder precoat coating is formed by the method of the present invention on the electronic component array aligned on the holder. Therefore, these are within the scope of the present invention.
In addition, the lead frame strips arranged in a matrix with multiple rows of multi-row electronic components wound in a coil shape are processed by the moving method and continuous feeding or intermittent feeding in the method of the present invention. I can do it.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　以上の通り、本発明は、従来法ならびにそれに類する先行技術の難点である、微細回路のはんだプリコート皮膜形成時のブリッジの問題、フラックス成分を含有するが故の接合界面やはんだ層内に所謂マイクロボイド（微小な気泡や空隙）発生現象を回避し、経時的接続信頼性の問題、腐食性の問題、更には長期高温暴露後に経時的に発生するカーケンダルボイドの問題を解決するもので、パッドまたはリード幅０．０２~０．０８ｍｍ、隣接ピッチ０．０４~０．１２ｍｍの微細狭ピッチ電子回路に３~２０μｍの厚さ範囲で厚さのばらつきが±３μ以内の錫またははんだプリコート皮膜形成をも、安定的に量産可能にする技術を提供するものであり、工業的価値が極めて高い画期的な技術である。 As described above, the present invention is a problem of the conventional method and similar prior art, such as a bridge problem when forming a solder precoat film of a fine circuit, a so-called micro-layer in a joint interface or a solder layer because it contains a flux component. It avoids the phenomenon of voids (small bubbles and voids), solves the problem of connection reliability over time, the problem of corrosiveness, and the problem of Kirkendall voids that occur over time after long-term high temperature exposure. Alternatively, a tin or solder precoat film with a thickness variation of within ± 3μ in a thickness range of 3-20μm on a fine narrow-pitch electronic circuit with a lead width of 0.02-0.08mm and an adjacent pitch of 0.04-0.12mm Is a groundbreaking technology that has a very high industrial value.
　１　電子回路基板または電子部品連結体（ワーク）
　２　粉末散布装置（上方から細かいメッシュの金網でできた篩、上部が広く下部に行くほど先端が細く狭まったロート状の容器、あるいは市販の粉末用散布装置や先端部に噴射散布ノズルを有する容器などに入れた固体の錫またははんだ粒子を散布する装置）
　３　粉末散布装置のノズル
　４　錫またははんだ微粒子
　５　高温の有機脂肪酸溶液貯槽
　６　高温の有機脂肪酸溶液
　７　高温の有機脂肪酸溶液移送用ポンプ
　８　高温の有機脂肪酸溶液移送用配管
　９　高温の有機脂肪酸溶液吹付け用ノズル
１０　ソルダーレジスト
１１　パッドまたはリード
１２　はんだブリッジ
１３　余剰の錫またははんだ球状物、ソルダーレジスト上に付着した塵埃などの不要物
１４　錫またははんだ皮膜
１５　溶融錫液またははんだ液
１６　溶融錫液または溶融はんだ液移送用ポンプ
１７　溶融錫液または溶融はんだ液の噴射ノズル
１８　有機脂肪酸溶液と溶融錫液または溶融はんだ液吹付け後の溢流（オーバーフロー）液（混合液）
１９　溢流混合液３９を受ける金属製の受皿樋
２０　撹拌器
２１　貯槽
２２　リバースロール
２３　バッフル
２４　アーム
２５　パイロットピン
２６　ワーク保持治具
２７　銅パットまたは銅リード
２８　錫銀、錫銅などの金属間化合物（ＩＭＣ）の偏析物
２９　錫銅ニッケルの金属間化合物（ＩＭＣ）層
３０　鉛フリーはんだ層
３１　錫銅ニッケル金属間合金層
３２　錫ニッケル層金属間合金層
３３　ガラスエポキシ基板
３４　パッドまたはリード表面に搭載した錫またははんだ微粒子が本発明の第２ステップで加熱されてパッドまたはリードに融着接合した錫またははんだ皮膜
３５　カーケンダルボイド（マイクロボイド） 1 Electronic circuit board or electronic component assembly (work)
2 Powder disperser (screen made of fine mesh wire mesh from above, funnel container with top narrower and narrower toward the bottom, or commercially available powder disperser or container with spray spray nozzle at tip For spraying solid tin or solder particles in
3 Powder spraying device nozzle 4 Tin or solder fine particle 5 High temperature organic fatty acid solution storage tank 6 High temperature organic fatty acid solution 7 High temperature organic fatty acid solution transfer pump 8 High temperature organic fatty acid solution transfer pipe 9 High temperature organic fatty acid solution spraying Nozzle 10 Solder resist 11 Pad or lead 12 Solder bridge 13 Excess tin or solder ball, unnecessary material such as dust adhering to the solder resist 14 Tin or solder film 15 Molten tin or solder liquid 16 Molten tin or molten Solder solution transfer pump 17 Injection nozzle 18 of molten tin solution or molten solder solution Overflow solution (mixed solution) after spraying organic fatty acid solution and molten tin solution or molten solder solution
19 Metal saucer bowl 20 for receiving overflow mixture 39 Stirrer 21 Storage tank 22 Reverse roll 23 Baffle 24 Arm 25 Pilot pin 26 Work holding jig 27 Copper pad or copper lead 28 Intermetallic compound such as tin silver, tin copper (IMC) segregated material 29 Tin-copper-nickel intermetallic compound (IMC) layer 30 Lead-free solder layer 31 Tin-copper-nickel intermetallic alloy layer 32 Tin-nickel layer intermetallic alloy layer 33 Glass epoxy substrate 34 Mounted on the pad or lead surface Tin or solder film 35 heated by the second step of the present invention and fused and bonded to the pad or lead 35 Kirkendall void (micro void)

Claims (13)

  1. 　電子回路基板または電子部品の狭ピッチ微小面積の電極パッドまたはリード表面に錫またははんだ皮膜を形成する方法において、パッドまたはリード以外の表面がソルダーレジスト膜で保護され、パッドまたはリードのみが露出している電子回路基板または電子部品連結体の清浄化された前記パッドまたは前記リード表面に、錫またははんだ微粒子を搭載させる第１ステップと、前記錫またははんだ微粒子を核として前記パッドまたは前記リード表面に融着させて錫またははんだ皮膜を形成させる第２ステップと、錫またははんだ皮膜表面に高温の有機脂肪酸溶液を吹付けて余剰に付着した前記錫またははんだを吹き落し除去する第３ステップと、により前記パッドまたは前記リードに均一な錫またははんだ皮膜を形成させることを特徴とする方法。 In a method of forming a tin or solder film on the surface of an electrode pad or lead having a small pitch on an electronic circuit board or electronic component, the surface other than the pad or lead is protected with a solder resist film, and only the pad or lead is exposed. A first step of mounting tin or solder fine particles on the cleaned pad or lead surface of the electronic circuit board or electronic component connected body, and melting on the pad or lead surface using the tin or solder fine particles as a core. A second step of depositing and forming a tin or solder film, and a third step of spraying and removing the excessively adhered tin or solder by spraying a hot organic fatty acid solution onto the surface of the tin or solder film. A uniform tin or solder film is formed on the pad or the lead. How.
  2. 　前記請求項１に記載の方法において、第１ステップでフラックスを介して錫またははんだ微粒子を搭載させることを特徴とする錫またははんだ皮膜の形成方法。 The method according to claim 1, wherein tin or solder fine particles are mounted via flux in the first step.
  3. 　前記請求項１、及び２に記載の方法において、前記フラックスはパルミチン酸ニッケル、パルミチン酸コバルト、ステアリン酸ニッケル、ステアリン酸コバルトのいずれか１種類以上を０．１~２０質量％含有することを特徴とする錫またははんだ皮膜の形成方法。 3. The method according to claim 1, wherein the flux contains 0.1 to 20% by mass of any one or more of nickel palmitate, cobalt palmitate, nickel stearate, and cobalt stearate. A method for forming a tin or solder film.
  4. 　前記請求項１に記載の方法において、前記均一な錫またははんだ皮膜は厚さが３~３０μｍ、厚さのばらつきが５μｍ以下であることを特徴とする錫またははんだ皮膜の形成方法。 2. The method according to claim 1, wherein the uniform tin or solder film has a thickness of 3 to 30 μm and a thickness variation of 5 μm or less.
  5. 　前記請求項１に記載の方法において、第３ステップで使用する前記有機脂肪酸溶液はパルミチン酸またはステアリン酸５~８０質量％と残部エステル合成油とからなることを特徴とする錫またははんだ皮膜の形成方法。 2. The method according to claim 1, wherein the organic fatty acid solution used in the third step comprises 5-80% by mass of palmitic acid or stearic acid and the remaining ester synthetic oil. Method.
  6. 　前記請求項１に記載の方法において使用する前記はんだ成分は、ニッケル０．００５~０．５質量％と、ゲルマニウム０．００１~０．１質量％またはリン０．００３~０．１質量％のいずれか１種以上と、残部錫または錫ヒスマス母合金と、からなることを特徴とするはんだ皮膜の形成方法。 The solder component used in the method according to claim 1 is composed of 0.005 to 0.5 mass% nickel, 0.001 to 0.1 mass% germanium, or 0.003 to 0.1 mass% phosphorus. A method for forming a solder film comprising any one or more of the remaining tin and a tin hiss master alloy.
  7. 　電子部品および／または半導体装置において、前記請求項１、２、３、４、５、または６のいずれかに記載の方法によりパッドまたはリードに錫またははんだ皮膜を形成させたことを特徴とする電子部品および／または半導体装置。 An electronic component and / or a semiconductor device, wherein a tin or a solder film is formed on a pad or a lead by the method according to any one of claims 1, 2, 3, 4, 5, or 6. Components and / or semiconductor devices.
  8. 　電子装置において、前記請求項７記載の電子部品および／または半導体装置を実装基板に搭載したことを特徴とする電子装置。 An electronic device comprising the electronic component and / or the semiconductor device according to claim 7 mounted on a mounting board.
  9. 　電子回路基板又は電子部品の狭ピッチ微小面積の電極パッドまたはリード表面に錫またははんだ皮膜を形成するための装置であって、パッドまたはリード以外の表面がソルダーレジスト膜で保護され、パッドまたはリードのみが露出している電子回路基板または電子部品連結体の清浄化された前記パッドまたは前記リード表面に、第１ステップとして錫またははんだ微粒子を搭載させる装置と、第２ステップとして前記錫またははんだ微粒子を核として前記パッドまたは前記リード表面に融着させて錫またははんだ皮膜を形成させる装置と、第３ステップとして錫またははんだ皮膜表面に高温の有機脂肪酸溶液を吹付けて余剰に付着した前記錫またははんだを吹き落し除去する装置と、を具備したことを特徴とする装置。 A device for forming a tin or solder film on the surface of an electrode pad or lead having a small pitch on an electronic circuit board or electronic component. The surface other than the pad or lead is protected by a solder resist film, and only the pad or lead is formed. An apparatus for mounting tin or solder fine particles as a first step on the cleaned pad or lead surface of an electronic circuit board or electronic component coupling body on which is exposed, and tin or solder fine particles as a second step An apparatus for forming tin or a solder film by fusing to the surface of the pad or the lead as a nucleus, and the tin or solder adhered excessively by spraying a high-temperature organic fatty acid solution on the surface of the tin or solder film as a third step And a device for blowing off and removing.
  10. 　前記請求項９に記載の装置において、第１ステップでフラックスを介して錫またははんだ微粒子を搭載させることを特徴とする錫またははんだ皮膜の形成装置。 10. An apparatus for forming a tin or solder film according to claim 9, wherein tin or solder fine particles are mounted via a flux in the first step.
  11. 　前記請求項９、及び１０に記載の装置において、前記フラックスはパルミチン酸ニッケル、パルミチン酸コバルト、ステアリン酸ニッケル、ステアリン酸コバルトのいずれか１種類以上を０．１~２０質量％含有することを特徴とする錫またははんだ皮膜の形成装置。 11. The apparatus according to claim 9, wherein the flux contains 0.1 to 20% by mass of any one or more of nickel palmitate, cobalt palmitate, nickel stearate, and cobalt stearate. An apparatus for forming a tin or solder film.
  12. 　前記請求項９に記載の装置において、前記有機脂肪酸溶液としてパルミチン酸またはステアリン酸５~８０質量％と、残部エステル合成油とからなることを特徴とする錫またははんだ皮膜形成装置。 10. The tin or solder film forming apparatus according to claim 9, wherein the organic fatty acid solution comprises 5-80% by mass of palmitic acid or stearic acid and the remaining ester synthetic oil.
  13. 　前記請求項９に記載の装置において、前記はんだ微粒子の成分は、ニッケル　０．００５~０．５質量％と、ゲルマニウム　０．００１~０．１質量％またはリン　０．００３~０．１質量％と、残部錫または錫ビスマス母合金と、からなることを特徴とするはんだ皮膜形成装置。 10. The apparatus according to claim 9, wherein the components of the solder fine particles are nickel 0.005-0.5% by mass, germanium 0.001-0.1% by mass, or phosphorus 0.003-0.1% by mass. And a remaining tin or a tin bismuth master alloy.
PCT/JP2010/073262 2010-11-05 2010-12-16 Method for forming tin or solder coat film and device therefor WO2012060022A1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014033172A (en) * 2012-11-02 2014-02-20 Tanigurogumi:Kk Component with electrode corrosion preventive layer, and method of manufacturing the same
JPWO2014148634A1 (en) * 2013-03-21 2017-02-16 株式会社谷黒組 Soldering apparatus and method, and manufactured board and electronic component
CN113035553A (en) * 2021-03-26 2021-06-25 四川长虹电子部品有限公司 Method for improving corrosion resistance and production efficiency of pin transformer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0410694A (en) * 1990-04-27 1992-01-14 Toshiba Corp Solder coating method of printed wiring board
JPH06252542A (en) * 1993-02-25 1994-09-09 Sharp Corp Method for forming solder layer
JP4203281B2 (en) * 2002-08-09 2008-12-24 日本ジョイント株式会社 Surface treatment method
JP2009105356A (en) * 2007-10-25 2009-05-14 Horizon Gijutsu Kenkyusho Kk Printed circuit board and surface treatment method for printed circuit board
JP4389112B2 (en) * 2008-01-17 2009-12-24 ホライゾン技術研究所株式会社 Semiconductor device and manufacturing method thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0410694A (en) * 1990-04-27 1992-01-14 Toshiba Corp Solder coating method of printed wiring board
JPH06252542A (en) * 1993-02-25 1994-09-09 Sharp Corp Method for forming solder layer
JP4203281B2 (en) * 2002-08-09 2008-12-24 日本ジョイント株式会社 Surface treatment method
JP2009105356A (en) * 2007-10-25 2009-05-14 Horizon Gijutsu Kenkyusho Kk Printed circuit board and surface treatment method for printed circuit board
JP4389112B2 (en) * 2008-01-17 2009-12-24 ホライゾン技術研究所株式会社 Semiconductor device and manufacturing method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014033172A (en) * 2012-11-02 2014-02-20 Tanigurogumi:Kk Component with electrode corrosion preventive layer, and method of manufacturing the same
JPWO2014148634A1 (en) * 2013-03-21 2017-02-16 株式会社谷黒組 Soldering apparatus and method, and manufactured board and electronic component
CN113035553A (en) * 2021-03-26 2021-06-25 四川长虹电子部品有限公司 Method for improving corrosion resistance and production efficiency of pin transformer
CN113035553B (en) * 2021-03-26 2023-03-24 四川长虹电子部品有限公司 Method for improving corrosion resistance and production efficiency of pin transformer

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