JP2011211137A - Semiconductor device and method of manufacturing the same, and electronic device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve bonding reliability of fine junctions of a semiconductor device and an electronic device.SOLUTION: A bump or solder coating is formed through a first process and a second process. In the first process, at least one or more tin or solder particles are bonded to metal surfaces of electrode pads or lead parts to be solder-bonded in a state wherein the tin or solder particles are scattered on the cleaned surfaces of all the exposed fine-pitch electrode pads or leads of a chip, a wafer, an interposer (wiring board), or a mounting substrate covered with a heat-resistive organic insulating protective film except electrode pads or lead parts to be solder-bonded. In the second process, the pad or lead metal surfaces are brought into contact with a solution containing a 1 to 95 mass% of an organic compound which is dissolved in an oil-based solvent of 180 to 300°C in liquid temperature and molecule-structurally stable, and has at least a carboxyl group (-COOH), a low-oxygen-concentration molten solder liquid of 5 ppm or below in oxygen concentration, and the organic compound solution again.

Description

  The present invention relates to a semiconductor device and a manufacturing technique thereof, and an electronic device and a manufacturing method thereof, and more particularly, a technique for forming small solder bumps on a large number of electrode pads arranged in parallel at a narrow pitch of a semiconductor device, and a mounting board as well. A technology that coats a small solder film on the surface of a large number of electrode pads or leads that are arranged in parallel at a narrow pitch, and all semiconductor wafers that have a large number of semiconductor chips in which a large number of electrode pads are arranged in parallel at a narrow pitch Semiconductor device in which minute solder bumps are formed on all electrode pads or leads existing in the chip and its manufacturing technology, and further, an electronic device formed by soldering these semiconductor devices and other electronic components to a mounting board And its manufacturing technology.

In recent years, electronic devices, in particular semiconductor chips and semiconductor devices, are increasingly required to be highly integrated, high density, small and light, and to have high quality. Correspondingly, electronic components such as resistors, capacitors, and connectors have been miniaturized and densified, and electronic devices that are mounted on a mounting board and soldered are increasingly miniaturized and densified.
Among semiconductor devices, semiconductor chips and interposers (wiring boards) of LSI, BGA (Ball Grid Array), CSP (Chip Size Package), etc., have been increasingly miniaturized and bumps and solder joints have also been made finer and finer. In addition, higher reliability is required. In particular, extremely strict reliability is required for the quality of the fine solder joint between the semiconductor chip and the interposer on which it is mounted.
For this reason, the bonding strength of the tin or solder alloy used for tin or solder bonding, especially the bonding area of electrode pads or leads of semiconductor chips and other electronic components, and the fineness of tin or solder accompanying the narrowing of adjacent pitches High reliability of the joint is required.

  On the other hand, in recent years, the use of lead has been banned or regulated due to environmental pollution and harm to the human body, and so-called “lead-free solder alloys” that do not contain lead are widely used for soldering, especially in the field of electronic components. In particular, tin / silver / copper solder alloys and solder alloys with antimony added thereto (patent document 1), tin / silver / copper solder alloys with nickel or germanium added, etc. (patent document) 2) etc. are proposed and put into practical use. In addition to these, a number of various solder alloys have been proposed, such as a tin / zinc / nickel solder alloy and a solder alloy further added with silver, copper, bismuth, etc. (Patent Document 3).

In general, in order to form a minute bump on a minute electrode pad of a CSP chip, a protective film is applied to all other surfaces except for the electrode pad part where the bump is formed, and the openings are opened after covering and protecting. The electrode pad metal surface (generally Au flash plating is applied on the underlying Ni plating) is used by electroforming gold bumps or solder bumps to a thickness of several tens of μm. However, in this case, gold is expensive, electroforming plating takes a long time, management is complicated and inefficient, and costs are high.
Also, the size and adjacent pitch of the solder bumps can be determined by using the current solder melted and used due to restrictions on the physical properties and joining technology of the current solder when the CSP is mounted on the mounting board and soldered. Solder ball or solder bump diameter formed by immersion of solder ball or solder due to the so-called “over volume” (tsuno, tsura) where the solder rises in the part with more capacity than necessary and the difficulty of leaking by bridging to adjacent leads Currently, it is said that the narrowing of about 80 μm and the adjacent pitch of about 200 μm is the limit at present. For example, the minute fine solder bumps having a bump diameter of 80 μm or less and an adjacent pitch of 150 μm or less are still completely other than the electroformed plating bumps. Has not been put to practical use.

On the other hand, as a method of soldering and mounting a semiconductor device or other electronic components such as capacitors, resistors, connectors, etc. on the surface of the mounting board pad or lead, the soldering pad or lead of the mounting board is excluded. Then, after covering all other surfaces with a protective film, a metal mask having openings corresponding to the pads or leads of the mounting board is overlaid on the mounting board, and a predetermined thickness is applied to the pads or leads of the mounting board with a roller or squeegee. The solder paste is printed and applied, then the metal mask is removed, and the automatic surface mounter (mounter) automatically mounts the specified electronic components on the specified pads or lead positions on the mounting board. Various parts are put into practice by passing them through a reflow oven heated to a temperature where soldering is possible. It has produced semiconductor devices or electronic devices soldered to the substrate.
However, current tin or solder alloys generally have several hundred ppm of metal oxide, so the viscosity at the time of melting is relatively high and the wettability is relatively low, so that the pad or lead width is particularly less than 80μ. When soldering a semiconductor device or other electronic component to a fine mounting substrate with a pitch of 150 μm or less, the solder rises with a capacity more than necessary even if an appropriate flux is used. In addition to the difficulty of leaking by bridging to “volume” (horns and wigs) and adjacent leads, the solvent and resin components contained in solder unattached, flux or solder paste, etc. are vaporized during soldering. Therefore, there is also a difficulty in producing macro voids (Patent Document 4). In addition, since the elongation, which is one of the physical and mechanical characteristics of the solder joint, is small, after being energized on-off after being incorporated into a semiconductor device or electronic device as an electronic circuit, the solder joint becomes fatigued due to heat cycles. It is widely known that breakage tends to occur, such as poor conduction, and impairs connection reliability of miniaturized electronic devices. (Patent Document 4)

  JP 5-50286 (Patent 3027441)   JP 11-77366 (Patent 3296289)   Japanese Patent Laid-Open No. 9-94688 (Patent 3299091)   JP2001-237536 (Patent 3216709)   JP2003-334498 (Patent No. 4153723)   JP 2002-233994 (Patent No. 4203281)

The present invention eliminates the above-mentioned disadvantages in tin or solder alloy for electronic parts and joining technology that have been practically used in the past, that is, "over volume" (horn, tsura) and leakage failure due to bridge over to adjacent leads, Bump diameter or lead width that was not possible with conventional technology using molten solder, and a circuit that enables direct soldering by using molten solder of a narrow pitch micro-fine chip with an adjacent pitch of 150 μm or less and an interposer that is less than 80 μm. And a manufacturing technique thereof, similarly, a semiconductor device at a predetermined position on a mounting substrate in which a surface of a narrow pitch pad or lead metal having a width of 80 μm or less and an adjacent pitch of 150 μm or less is directly solder-coated with molten solder And other electronic components that are surface-mounted by direct solder bonding with molten solder It is to provide a manufacturing technique.
As a result, a semiconductor device that is simple, convenient, economical, efficient, and reliable in quality without using a conventional expensive metal mask or solder paste, and its manufacturing technology, as well as an electronic device and its manufacturing technology Is to provide.

A semiconductor device and a manufacturing method thereof, and an electronic device and a manufacturing method thereof according to the present invention include a chip covered with a protective film other than pads or leads to be soldered, a wafer in which a large number of chips are arranged in parallel, and a BGA interposer. Alternatively, tin or solder particles are dispersed in a clean metal surface of all exposed pads or leads of the mounting substrate, and at least one or more of the particles are dispersed to adhere to the clean metal surface of each pad or lead. A first process, and then a chip, a wafer, an interposer, or a mounting substrate having tin or solder particles bonded to the pad or lead is dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. A solution containing 1% by mass or more of an organic compound which is stable and has at least a carboxyl group (—COOH), or After the contact with the 00% organic compound simple substance liquid, the pad or lead is immediately brought into contact with the low oxygen concentration molten solder liquid having an oxygen concentration of 5 ppm or less, and again immediately brought into contact with the solution or the 100% simple substance liquid. A solder bump or solder film is formed directly on the surface. As a result, a chip, a wafer, an interposer, or a mounting substrate having a lead in which a fine solder bump or a fine solder film is formed without bridging the tin or solder on an adjacent circuit having a narrow pitch, and a combination thereof, can be trusted. High-performance semiconductor devices and electronic devices can be manufactured.
For example, a BGA semiconductor device or the like mounts bumps on a chip on which micro bumps are formed at a narrow pitch in accordance with the first and second processes in accordance with the positions of interposer pads. A semiconductor device can be manufactured by forming a circuit by melting the solder and solder-bonding between the chip and the electrodes of the interposer.
Further, when the chip is mounted on the interposer, a part of the protective film other than the bump and a protective film part other than the interposer pad corresponding to the position of the chip are bonded via a heat-resistant adhesive. After fixing the position, a solution containing 1% by mass or more of an organic compound which is dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. and which is stable in molecular structure and has at least a carboxyl group (—COOH) or 100% After contacting with the organic compound simple substance liquid, it is immediately brought into contact with a low oxygen concentration molten solder liquid having an oxygen concentration of 5 ppm or less, and immediately again with the organic compound solution or 100% simple substance liquid, the adjacent circuit with a narrow pitch can be obtained. More reliable semiconductor by soldering the chip to the electrode pad or lead of the interposer without bridge over leak It is possible to manufacture the location.
Similarly, in an electronic device, the bumps of a semiconductor device such as CSP and BGA in which minute bumps are formed at a narrow pitch by the first and second processes, and other electronic components whose outer leads are coated with solder The electrode pads or leads corresponding to the positions of these leads are exposed, and the other surfaces are mounted at predetermined positions on the mounting substrate covered with a protective film, and the bumps, outer An electronic device can be manufactured by forming a circuit by melting the lead solder and soldering the pads or leads of the mounting substrate to the semiconductor device and other electronic components. Also in this case, when mounting the semiconductor device and other electronic components on a mounting substrate, a part of the protective film other than the bumps of the semiconductor device, and insulating portions other than outer leads of the other electronic components, After fixing the position with a protective part other than the pad or lead of the mounting board corresponding to the position via a heat-resistant adhesive, it is dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. and has a molecular structure In contact with an organic compound solution containing 1% by mass or more of an organic compound having at least a carboxyl group or a 100% simple substance solution, and immediately brought into contact with a low oxygen concentration molten solder solution having an oxygen concentration of 5 ppm or less. By contacting with a solution or 100% simple substance solution, a semiconductor device and its adjacent circuit without a bridge over leak in a narrow pitch adjacent circuit The electrode pads or leads of a mounting board electronic component is to enable the production of a solder joint to highly reliable electronic device.

Further, for example, an interposer processed by the first process or an interposer processed by the first and second processes on a chip on which micro bumps are formed at a narrow pitch by the first and second processes. It is also possible to manufacture a semiconductor device by forming a circuit by mounting corresponding to the position of the electrode pad of the poser, melting the solder of the bump in a heated atmosphere, and solder-bonding between the chip and the electrode of the interposer. . Also in this case, desirably, when the chip is mounted on the interposer, a part of the protective film other than the bump of the chip and a protective film portion other than the electrode pad of the interposer corresponding to the position are provided. 1 mass of an organic compound having a molecular structure stable and having at least a carboxyl group (—COOH) dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. % Or more of the organic compound solution containing 100% by mass or more, and immediately contacting with a low oxygen concentration molten solder solution having an oxygen concentration of 5 ppm or less, and immediately contacting with the organic compound solution again. By doing so, the chip is soldered to the electrode pad of the interposer without the bridge over leak of the adjacent circuit with a narrow pitch. It is intended to allow the production of more highly reliable semiconductor device.
Similarly, in the electronic device, the bumps of a semiconductor device such as CSP and BGA in which minute bumps are formed at a narrow pitch by the first and second processes, and other electronic components whose outer leads are coated with solder Leads are mounted corresponding to the positions of electrode pads or leads on the mounting substrate processed in the first process or the mounting substrates processed in the first and second processes, and the bumps or leads are mounted in a heated atmosphere. An electronic device can be manufactured by forming a circuit by melting the solder and soldering the semiconductor device and other electronic components to the electrode pads or leads of the mounting substrate. In this case also, preferably, when mounting the semiconductor device and other electronic components on a mounting substrate, a part of the insulating protective film other than the bumps of the semiconductor device and an insulating portion other than the outer leads of the other electronic components , And a protective film other than the electrode pads or leads of the mounting substrate corresponding to these positions are bonded via a heat-resistant adhesive, and then dissolved in an oil-based solvent at a liquid temperature of 180 to 300 ° C. and have a molecular structure After being brought into contact with an organic compound solution containing at least 1% by mass of an organic compound having a carboxyl group (—COOH) or 100% by mass of the organic compound, the oxygen concentration melts immediately at an oxygen concentration of 5 ppm or less. Narrow-pitch adjacent circuits are brought into contact with the solder solution and immediately again brought into contact with the organic compound solution or the single solution. The semiconductor device and the other electrode pads or leads of a mounting board electronic components without bridging is to enable the production of a solder joint to highly reliable electronic device.

  More specifically, in the first process, “each electrode pad is dispersed by spraying tin or solder particles in the clean metal surface of all electrode pads or leads, and at least one or more of the particles are dispersed and heated at a high temperature. The purpose of “adhering to the clean metal surface of the lead” is to draw molten solder into the electrode pad or lead to form a good solder bump or solder film. That is, the surface of the chip, interposer, or mounting substrate is exposed only on the electrode pad or lead, but the other surfaces are covered with a protective film having a thickness of several μm to several tens of μm (electrode pad or Minimum width of lead, adjacent pitch, and also varies depending on application and purpose), especially electrode pad or lead with minimum width and surrounded by thick protective film (for example, width 20 μm, protective film thickness 20 μm or more Etc.), even when a molten solder solution with good wettability is used, the problem of the wetting angle peculiar to molten solder and the air existing in the part surrounded by the protective film become obstacles, and the bottom electrode pad or lead surface Since molten solder cannot be contacted, it is almost impossible to form a solder film on the solder bump. For this reason, in the method of the present invention, tin or solder particles having a diameter of 0.5 to 20 μmφ are used as a core for attracting the molten solder liquid depending on the minimum width of the electrode pad or lead.

  The material of the particles may be pure tin or a normal solder alloy containing normal tin as a main component and containing at least one of silver, copper, zinc, lead, bismuth, antimony, nickel, germanium, indium and the like. However, the oxygen concentration is desirably 5 ppm or less. From the viewpoint of rolling properties, the particle shape is preferably a spherical shape that is close to a perfect circle and has a smooth surface, and preferably has no so-called voids or microvoids inside. Those having a rough surface or a porous surface are not preferred because of their poor rolling properties. Also, in the case where voids or microvoids are present inside or the whole particles are porous, when the solder bump or solder film is formed by combining with the molten solder in the second process, There is a possibility that microvoids may be scattered at the bonding interface with the electrode pad or lead, and this is not preferable because it causes deterioration of bonding strength over time.

In addition, small particles or powders with a particle size of less than 0.5 μmφ are less likely to roll, more susceptible to static electricity, difficult to spread evenly, and many more than necessary inside electrode pads or leads. When particles are deposited and become nuclei when forming nuclei, and when they are combined with molten solder in the second process to form solder bumps or solder films, the interior of the bumps or solder films, electrode pads or There is a possibility that microvoids may be present at the bonding interface with the lead, which is not preferable because it causes deterioration in bonding strength over time.
Accordingly, the desirable particle diameter is 5 to 40 μmφ, but the upper limit is limited by the minimum width of the electrode pad or lead, which is lower than the enclosed protective film thickness and is 0.3 to 0.3 mm which is the minimum width of the pad or lead. A spherical body with a diameter of about 0.8 times is optimal.

As a method of dispersing one or more tin or solder particles to disperse one or more electrode pads or lead surfaces surrounded by a protective film, simply place the electrode pads or lead surfaces on the upper surface. The method of mechanically sprinkling the particles from the whole surface, the method of using the vibration, the method of dispersing the particles in ultrapure water and spraying with the ultrapure water, the volatile solvent instead of the ultrapure water A method in which the above particles are dispersed and sprayed, or a method in which an electrode pad or a lead having a mask corresponding to the arrangement and shape of the lead portion and a brush are used for transfer, and further on molten tin or molten solder. There is a method of spraying molten tin or solder particles from a nozzle while directly irradiating ultrasonic waves. Also, using a special jig made of powder sintering corresponding to the center position of each electrode pad or lead and having a hemispherical hole corresponding to the size of the transferred particles, 1 to 3 in the hemisphere An automatic transfer machine that sucks individual particles and transfers them to each electrode pad or lead may be used.
In addition, when using the dedicated mask jig or automatic transfer machine and simply sprinkling the entire surface of the chip, wafer, interposer, or mounting substrate, excess particles remaining on the protective film other than the electrode pads or leads Although it has never been eliminated, there is no problem even if it is not eliminated, since it can be washed away with an organic compound solution in the second process and is taken into the molten solder solution. However, if the composition of the particles and the composition of the molten solder solution used in the present invention are different, the component ratio in the molten solder solution that is the main body changes with time, which is not preferable. In this case, it is desirable to use a solder having the same composition as the solder used in the second process as the particles used for the core.

  As a method for adhering one or more of the tin or solder particles scattered on the surface of the electrode pad or lead surrounded by a protective film to the surface, the melting point of the particles is within + 50 ° C. and about 0.5 to 10 seconds. It is sufficient to bond by heating. There is also an efficient method in which the particles are sprinkled onto a pre-warmed object (work) and the particles are directly bonded when they reach the electrode pad or lead surface of the work. Alternatively, it is also effective to disperse and adhere to the electrode pad or the lead surface while passing through a high-temperature organic fatty acid solution within the melting point to + 50 ° C. of the particles.

  On the other hand, the second process, that is, “chip, wafer, interposer (wiring board) or mounting board in which tin or solder alloy is partially bonded to the electrode pad or lead part is made into an oil-based solvent having a liquid temperature of 180 to 300 ° C. After contacting with an organic compound solution containing 1% by mass or more of an organic compound which is dissolved and stable in molecular structure and has at least a carboxyl group (—COOH) or 100% by mass of the organic compound, an oxygen concentration of 5 ppm or less immediately The purpose of “contacting with a low oxygen concentration molten solder solution of the above and immediately contacting with the organic compound solution again” is a unique and excellent characteristic in the molten state of a special solder refined to an oxygen concentration of 5 ppm or less, that is, the general composition of the same composition Compared to solder (containing several hundred ppm of oxygen), the viscosity in the molten state is remarkably low, and the solidification temperature is 10-30. In particular, a solution containing 1% by mass or more of an organic compound which is dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. and which is stable in molecular structure and has at least a carboxyl group (—COOH) or 100% by mass of the organic compound When used in combination with a single solution, solder "cuts" well, making it difficult to over-volume, thus making it difficult to generate bridges, and forming circuits with fine bumps and fine leads at narrow pitches. Another object is to achieve further downsizing while ensuring high reliability of the electronic device.

  The purpose of using an organic compound solution having a carboxyl group (—COOH) in this process is to clean and activate the pad or lead metal surface by removing the oxide film by a saponification reaction, and at the same time clean and activated surface. In addition to preventing oxidation of the low oxygen concentration molten solder solution having an oxygen concentration of 5 ppm or less to be used together and removing the mixed oxide from the molten solder solution, The surface is also coated as a chemisorption protective film. In addition to this, there is an effect that the extra particles adhering to the surface of the workpiece protective film in the first process are washed away to some extent. These functions, effects, and surface treatment techniques are already known from Patent Documents 5 and 6.

In addition, the organic compound used in the process of the present invention is essential to be an organic compound having at least a carboxyl group (—COOH). For example, methanoic acid (formic acid), ethanoic acid (acetic acid), propionic acid, butyric acid, Isobutyric acid, α-methyl-β-oxybutyric acid, valeric acid, isovaleric acid, active valeric acid, pivalic acid (trimethylacetic acid), 2-ethylbutyric acid, 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, linolenic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, cyclohexanecarboxylic acid, Succinic acid, malonic acid, succinic acid, glutaric acid, ethylmalonic acid, adipic acid, pimelic acid, Vacic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid and its isomers, benzoic acid, toluic acid, phenylacetic acid, phenylsuccinic acid, phthalic acid, isophthalic acid, salicylic acid, α-naphthoic acid, β-naphthoic acid, calcein, cyclohexane Organic acids and organic fatty acids such as propanedicarboxylic acid, nitrophthalic acid, glycine, aspartic acid, glutamic acid, alanine, phenylalanine, threonine, methionine, lysine, histidine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, 1,2-cyclohexanediaminetetraacetic acid, Examples include organic compounds such as chelate compounds such as glycol ether diamine tetraacetic acid. .
Among these, an organic compound which is desirably dissolved in a solvent used at 180 to 300 ° C. and stable without decomposition is preferable. In the case of an organic compound having a low boiling point, it can be used at a high pressure, but it is not preferable in terms of safety and practicality. Industrially more suitable for practical use in view of economy and handling, 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 are water-absorbing and are not very desirable due to their use at high temperatures. Furthermore, even if they are coated as a protective film on the solder surface after bonding, they are water-absorbing and thus are stored for a long time. It is not preferable because it may cause trouble in quality of time. Although organic fatty acids having 21 or more carbon atoms can be used, they have a high melting point, poor permeability and are difficult to handle, and the rust preventive effect of the treated tin or solder alloy is somewhat insufficient. Particularly preferable is industrially produced in large quantities and easily used because it is readily available, and 16-carbon palmitic acid and 18-carbon stearic acid are suitable, and one or more of them is 1 to 95% by weight. The effect of the present invention is also great when a solution having a liquid temperature of 180 to 300 ° C. made of an oil-based solvent that is stable in the high temperature region of 180 to 350 ° C. is used.

Even if the concentration of the liquid organic compound is 1% by mass or less, a sufficient effect is obtained, but replenishment management is complicated when it is continuously used in large quantities, and 80% by mass or more or 100% by mass alone can be used. Although the effect of the invention is present and can be used, it is preferably 5 to 80% by mass because the problem of smoke generation and odor is also severe.
The liquid temperature is determined by the temperature of the molten solder to be used, and it is efficient and desirable to be within a range of ± 20 ° C. from the liquid temperature of the molten solder. However, the upper limit temperature is about 320 ° C. in consideration of ignitability, smoke generation and safety, but about 300 ° C. or less is desirable from the viewpoint of odor and further energy saving.

  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 is a solvent that dissolves the organic compound and is stable in the high temperature range, but is particularly stable, safe and economical. Ester synthetic oil is the most suitable in terms of the properties and handling properties. The purpose and reason for using a solvent that is stable at high temperatures is not particularly effective, but to put it in a strong sense, it is to suppress high-temperature smoke generation and odor mitigation of the organic compounds, and slightly lower the viscosity and slightly improve permeability. Is done. The concentration is determined by the concentration of the organic compound.

  On the other hand, the molten solder liquid used in combination in the second process must use a molten solder refined to an oxygen concentration of 5 ppm or less. The reason for this is that, since commercially available pure tin, which is the main raw material of solder, and various solder master alloys have a minute amount of tin oxide of several hundred ppm, when they are melted and used for solder joining, the present invention Since the viscosity and the solidification temperature are higher than those of the molten solder solution with an oxygen concentration of 5 ppm or less used for the solder, the “cut” of the solder when the soldered joint is drawn out from the molten solder solution after soldering is poor. This is used in the present invention because it has a large swell and is likely to generate so-called over-volume (horn, icicle), and in a narrow pitch circuit, it bridges to an adjacent circuit and frequently causes a leak failure (FIG. 3-3b). Solder with an oxygen concentration of 5 ppm or less has a relatively low viscosity and solidification temperature in the melted state, and it is clearly free-flowing. Since the “cut” of the solder at the time of drawing out from the liquid is remarkably good, for example, even in a circuit where the lead width is 20 μm and the adjacent bitch is 60 μm, there is no overvolume, so there is no bridge over and no leak failure is caused (see FIG. 3-3a, 3c).

As a method for producing a solder having an oxygen concentration of 5 ppm or less used in the present invention, a commercially available refined tin and a molten solder solution obtained by melting a refined metal or a solder mother alloy necessary for a solder composition are used in the present invention. Injecting into a solution containing 1 to 95% by mass of an organic compound dissolved in an oil-based solvent having a temperature of 180 to 300 ° C. and having a stable molecular structure and having at least a carboxyl group (—COOH), and vigorously stirring treatment Thus, the fine oxides and impure metals present in the molten solder are removed by the saponification reaction of the organic fatty acid, and the oxygen concentration can be refined to 5 ppm or less.
Specifically, for example, a commercially available Ag 2.5 mass% Ag, 0.5 mass% Cu, 0.01 mass% nickel, 0.005 mass% germanium, and a tin-silver-copper-based lead-free solder alloy composed of the remaining tin were melted. If the molten solder solution with a liquid temperature of 260 ° C. is dripped into a solution with a liquid temperature of 260 ° C. composed of 50% by weight of palmitic acid and the remaining ester synthetic oil while vigorously stirring and mixing for 1 hour, the saponification reaction is promoted. Then, fine oxides and impure metals present in the molten solder solution are removed, and a solder having an oxygen concentration of 5 ppm or less is obtained. When the oxygen concentration in the solder is 5 ppm or less, the viscosity when melted is overwhelmingly lower than that of solder with an oxygen concentration of several tens to several hundred ppm. The crystallization and freezing point is low, so the so-called “solder breakage” when pulling up the workpiece from the soldering solution is very good, and there is no excessive solder bulging, which causes the so-called “over volume”, “tsuno” and “smooth” phenomenon. It has been found that there is a merit that it is difficult to cause a leak failure due to a solder bridge in a minute narrow pitch circuit.

The kind of tin or solder alloy applicable to the present invention is usually used for joining electronic components, and can be used if it is purified to an oxygen concentration of 5 ppm or less by performing the same treatment as described above. From the viewpoint of bonding reliability, it is desirable to use tin or a molten lead-free solder alloy containing tin as a main component and at least one of silver, copper, zinc, bismuth, antimony, nickel, and germanium. Is preferred.
Examples of practical verification of the present invention are mainly tin / silver / copper and nickel / germanium-added solder and tin / zinc-based nickel / silver added low oxygen concentration solder with oxygen concentration of 5 ppm or less. However, other lead-free solder alloys, pure tin, and tin-lead solder alloys can be obtained by refining them to an oxygen concentration of 5 ppm or less and applying them to the second process of the present invention. Estimated. This is because the refined raw material tin is dotted with ultrafine tin oxide particles of about several tens of nanomicrons, and the solder alloys manufactured using the raw materials as raw materials are equivalent to several tens or more. This is because ultrafine tin oxide particles of about nano microns are scattered.
Again, the low oxygen concentration solder refined to an oxygen concentration of 5 ppm or less has physical, mechanical and chemical properties that are not found in conventional solders. In particular, it is flexible, stretchable, tough, and has a markedly lower viscosity when melted (the apparent sensation is clearly “smooth” compared to conventional tin and solder alloys), and has good wettability, so it melts. "Solder breakage" when drawing out from the solder solution is good. By using this, it is possible not only for micro lead / narrow lead pitch circuits with a circuit width of 80 μm or less and an adjacent circuit pitch of 150 μm or less, which is almost impossible with conventional molten solder. Even a circuit with a circuit width of 10 to 20 μm and an adjacent pitch of 20 to 50 μm does not generate horns, wiggles, solder bridges, high-density microelectronic circuits with high bonding reliability, and high bonding reliability in which they are assembled High-density semiconductor device and electronic device can be manufactured.
On the other hand, when the oxygen concentration is 10 ppm or more, as the oxygen concentration increases, the viscosity increases, the “solder breakage” when drawn from the molten solder solution is poor, the freezing point is high, and a bridge is clearly easily formed. As a result of detailed studies on the relationship between the oxygen concentration and “solder breakage” and “bridge”, the inventors have found that the physical, mechanical and chemical properties, that is, particularly flexible and stretchable, and toughness, are around 5 ppm as described above. It was found that there was an inflection point of richness, solidification temperature drop, and viscosity at the time of melting, and 5 ppm was found to be a critical point.

Further, in the second process of the method of the present invention, the organic fatty acid solution and a low oxygen concentration of 5 ppm or less on the solder-bonded surface of an object (workpiece) to be solder bumped or solder-covered on a pad or lead of an electronic circuit. Although it is an indispensable condition to contact the oxygen concentration molten solder solution, the simplest concrete method is to put both solutions in one tank and leave them in a certain temperature range, and leave the organic matter due to the difference in specific gravity. When the workpiece is immersed in the upper and lower layers of the fatty acid solution on the upper layer and the molten solder solution on the lower layer, the workpiece surface of the workpiece is first cleaned and activated with the upper organic fatty acid solution, and a protective film is formed. Is done. Next, when the workpiece is pushed down and immersed in the molten solder solution in the lower layer, the wettability is good, and for example, about 0.1 to 1 second (pad or lead surface condition or heat / insulation protective film surrounding it) Depending on the thickness or height of the walls and the shape of the core particles adhered in the first process, the molten solder solution is drawn and soldered to the surface. After that, when the work is pulled up, the solder "cut" is good when the solder joint comes out from the lower layer, so the amount of solder to be joined does not over-volume, and therefore the appropriate amount of solder bump or solder film without bridging between adjacent circuits Can be formed. When the workpiece is further pulled up, it inevitably passes again through the upper organic fatty acid solution, so that the organic fatty acid is chemically adsorbed on the surface of the solder bump or solder film joined at that time, and a protective film is formed.
As a method of bringing the organic fatty acid solution and the low oxygen concentration molten solder solution having an oxygen concentration of 10 ppm or less into contact with the soldered joining surface of other objects (workpieces), each solution is circulated and supplied to the nozzle by a pump. There are also a method of spraying and spraying, and a method of circulating and supplying each liquid to separate tanks with a pump and passing the workpiece through the work, and processing. In any case, it is necessary to individually treat the organic fatty acid solution, the molten solder solution, and the organic fatty acid solution again in this order. In either case, the same effect as the upper and lower two-layer method is obtained and effective.
In the case of the jet method, the nozzle needs to be appropriately devised depending on the size and shape of the work, but in general, a slit-like nozzle is preferably used.
In addition, a jet slit nozzle for the molten solder is provided in a tank filled with the organic fatty acid solution, and the molten solder liquid is jetted in the organic fatty acid solution to immerse a work from above, the organic fatty acid solution, There is also a method in which the molten solder solution and the organic fatty acid solution are contacted again in this order. In this case, the workpiece may be moved vertically, or the soldered joint surface may be moved with an inclination angle obliquely upward or obliquely downward.

As described above, the method of the present invention, that is, a clean metal surface of an electrode pad or lead of a chip, wafer, interposer or mounting substrate in which the electrode pad or lead is exposed and the other part is covered with a protective film Further, after spraying tin or solder particles having a size of 0.5 to 40 μmφ to disperse at least one of the particles in all the electrode pads or leads, the mounting substrate is heated in the heating atmosphere. A first process for adhering to the surface of the pad or lead metal, and dissolving the chip, wafer, interposer or mounting substrate in an oil-based solvent having a liquid temperature of 180 to 300 ° C. and stable in molecular structure and at least a carboxyl group (− After contact with an organic compound solution containing 1% by mass or more of an organic compound having COOH) or 100% by mass of the organic compound alone Immediately contact with a low oxygen concentration molten solder solution having an oxygen concentration of 5 ppm or less, and then immediately contact again with the organic compound solution or 100% by mass organic compound simple substance solution to form a solder film on the electrode pad or lead surface. The second process forms a stable and good solder bump and solder film with a very narrow pitch with a pad or lead width of 80 μm or less and an adjacent pitch of 150 μm or less, no over-volume and no solder bridge failure with the adjacent circuit. I found that I can do it. That is, if the technology of the present invention is used, even a minute and fine pitch electronic circuit having a pad or lead width of 10 to 50 μm and an adjacent pitch of 20 to 120 μm (adjacent minimum space width is 10 μm depending on the lead width) is stable. As a result, it is possible to manufacture a small solder bump or a small solder film on a pad or a lead on a minute fine pitch electronic circuit of a chip, a wafer on which a large number of chips are arranged, an interposer, or a mounting substrate. Can be stably manufactured without over-volume and without bridging leakage with the adjacent circuit, and the semiconductor device and the electronic device can be further miniaturized. This is almost impossible with the conventional molten solder joining technique, and the effect of the present invention is extremely valuable industrially.
This will be described in more detail below with specific examples.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which showed typically the structure of the semiconductor device example which is embodiment of this invention, and the electronic device example, 1a is a cross-sectional example of CSP (Chip Size Package), 1b is a cross-sectional example of BGA (Ball Grid Array) 1c is an example of a plane of an electronic device on which a semiconductor device and other electronic components are mounted, and 1d is an example of a cross section of an electronic device on which a semiconductor device and other electronic components are mounted. The internal cross-sectional crystal structure of the solder alloy of the Example of this invention and a comparative example is shown, 2a is Example 1, 2b is Comparative Example 1, 2c is Example 2, 2d is the example of Comparative Example 2. Industrial application examples in which the lead-free solder alloys of Example 2 of the present invention and the conventional comparative example 2 are applied to a narrow-pitch mounting board (work A) having a very small width of 20 μm and an interval between adjacent circuits of 60 μm. 3a is an appearance photograph of Example 2 enlarged from the top, 3b is an appearance photograph of Comparative Example 2 that is enlarged from the top, and 3c is an enlarged photograph of the above 2a from the oblique upper part. It is a photograph.

DESCRIPTION OF SYMBOLS 1 Electrode pad 2 Core which adhered solder particle to electrode pad surface 3 Low oxygen concentration solder joined to electrode pad or lead surface Bump or solder film 4 Protective film 5 Sealing resin 6 Chip 7 Interposer 8 Au wire bonding Wire 9 Mounting substrate 10 BGA semiconductor device 11 CSP semiconductor device 12 DIP semiconductor device 13 BGA semiconductor device 14 Mini transistor 15 Chip capacitor 16 Resistor 17 Electronic device (module)

First, the solder compositions and experimental conditions used in the examples and comparative examples are shown in [Table 1].
As a common experimental condition, a test mounting substrate work A (FIG. 1-1a) in which 100 × 50 fine narrow pitch patterns having a lead width of 20 μm × a length of 360 μm and an adjacent pitch of 60 μ are arranged in a matrix and an electrode having an area of 40 μm × 40 μm Using test wafer work B (FIG. 1-1b) in which 20 × 20 pads arranged in a matrix with pads of adjacent pitch of 100 μm are arranged in a matrix of 10 × 10,
1) For Examples 1-3 and Comparative Example 2, the first process of the present invention, i.e. Example 1 in the clean metal surface of all the leads of A and all the electrode pads of B One to several particles of solder particles having the same composition and particle size of 8 to 18 μm are dispersed and left to stand in a reflow furnace at 260 ° C. for 5 seconds. Then, as a second process, after the workpieces A and B are brought into contact with each organic compound solution having a carbonyl group (—COOH) at a temperature of 260 ° C., the workpieces A and B are immediately brought into contact with each molten solder solution and immediately again. In contact with each organic compound solution, a solder film was formed on the lead of the work A, and a solder bump was formed on the electrode pad of the work B.
2) On the other hand, for Comparative Examples 1 and 3, a commercially available solder paste was applied to the leads or electrode pads of the workpieces A and B using a metal mask, and then left in a reflow oven at 260 ° C. for 5 seconds.

First, prior to the above experiment, oxygen concentration analysis, physical mechanical characteristics, and chemical characteristics in the lead-free solders of the comparative examples and examples were examined.
About oxygen concentration, the oxygen concentration inside the lead-free solder of Comparative Examples 1 to 3 and Examples 1 to 4 (from the surface to a depth of 10 μm) was measured by a TOF-SIMS analyzer.
Each solder was individually put into a viscosity alumina crucible, dissolved in an argon atmosphere, and the temperature was gradually lowered from 300 ° C. to the freezing point, and measurement was performed using an alumina vibrating piece viscometer.
For solder wettability, a 0.4 mmφ pure copper wire was used as a measuring pin in a solder bath in which the solder alloys of the comparative examples and examples were separately melted and automatically controlled at a liquid temperature of 260 ° C. The zero-crossing time was measured repeatedly 4 (n = 4) by a solder wettability test method using a meniscograph.
The melting temperature and solidification temperature of the solder used in each example and comparative example were recorded and analyzed using a differential thermal analyzer.
As a physical-mechanical evaluation method, each of the solder alloys of the comparative example and the example was made of a cast metal mold (JIS No. 6) made of stainless steel (SUS 304), the distance between ratings L = 50 mm, diameter 8 mmφ, chucking A test piece having a part length of L = 20 mm and a diameter of 10 mmφ was prepared, and repeatedly using a tensile tester (AG100 type) manufactured by Shimadzu Corporation according to the test method of JIS Z 4421) at a room temperature of 25 ° C. with 2 (n = 2) each. Further, the test load was measured at a load load speed of 5 mm / min. Further, for over-volume characteristics (whether horns and wigs were generated) and bridging characteristics, the binocular stereomicroscope (10 to 40 times zoom) was used for each of the comparative examples and examples. Each sample prepared in the experiment was observed and evaluated.

As a result, first, various characteristic values of each solder are as shown in the following [Table 2]. Each low oxygen concentration solder used in Examples 1 to 4 has an oxygen concentration of 5 ppm or less. It can be seen that fine oxides are scattered inside at 70 to 140 ppm. Further, even in the case of mechanical characteristic values, each of the solders of the example had a significantly larger elongation than that of the comparative example, and the tensile strength was not significantly different. Therefore, it was found that the example was excellent in toughness. On the contrary, it was confirmed that the normal solder of the comparative example had a small elongation and was hard and fragile.
On the other hand, the viscosity in the molten state (viscosity) was measured by gradually decreasing the temperature from 300 ° C. to the vicinity of the freezing point and measuring every 5 ° C., whereas the comparative example was 0.005 to 0.007 Pa · S. The solder used in the examples of the present invention was found to have an overwhelmingly low viscosity at 0.003 to 0.004 Pa · S, which also improved the “solder wettability” and removed the workpiece from the molten solder liquid. “Solder breakage” at the time of drawing out seems to be a good cause, and it is thought that it greatly contributes to the suppression of “over volume” and “bridge failure”. However, in particular, regarding the goodness of “solder breakage” in the examples, “not to be over-volume”, and therefore “no bridging failure”, not only the effect of the characteristic of low oxygen concentration solder, but also an organic compound having a carboxyl group This is a synergistic effect shared with the solution or the organic compound simple substance solution.
Furthermore, the results of analysis with the differential thermal analyzer for the examples and comparative examples show that although the melting point at the time of temperature rise is almost the same at around 217 ° C. in the tin-silver-copper solder used in the experiment, As for the solidification characteristics when the temperature is lowered, the comparative example starts to solidify at around 218 ° C. and completes at around 213 ° C., whereas in the examples of the present invention, only a part of the solidification starts to occur at around 218 ° C. The product started to solidify at around 215 ° C, and even when it dropped to around 204 ° C, it still solidified only about half, and finally solidification was completed at around 189 ° C. In contrast to the fine granular crystals (FIGS. 2-2a and 2c), it has been found that all of the comparative examples have a coarse crystal form (FIGS. 2-2b and 2d) containing a relatively large amount of columnar crystals. Clearly, there is a significant difference in physical properties It was found.
Considering the above together, the metal composition of the solder corresponds to Example 1 and Comparative Example 1, as well as Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 correspond to each other in the same composition. Regardless, as described above, in the examples, the solder of the comparative example corresponding thereto was purified to make the oxygen concentration 5 ppm or less, and the viscosity (viscosity), elongation, toughness, solidification temperature, crystal grain size in the molten state were reduced. There was a significant difference in any of the characteristics of solder wettability, and it was verified that the examples of the present invention were excellent. Thus, by combining the first process and the second process of the present invention, it becomes possible to form a fine narrow pitch solder bump and a solder film. By applying this technique, the semiconductor device and the electronic device can be further reduced in size. Can be realized.

  On the other hand, a prototype (Examples 1 to 4) in which the technology of the present invention is applied to a prototype chip and a mounting substrate approximated to an actual chip and a mounting substrate, and a similar prototype chip and mounting substrate prototyped by the conventional technology For the prototypes (Comparative Examples 1 to 3), the results of examining the over-volume property and the bridging (defect) property in the minute narrow-pitch circuit showed that all the Examples 1 to 4 had no over-volume and no bridging failure (FIGS. 3-3a and 3c) In all of the comparative examples, overvolume and bridges were observed in the local part or most of the adjacent parts (FIG. 3-3b) [Table 3].

  As described above, the technology of the present invention is obviously a fine pad or lead having a width of 50 μm or less, a solder bump or a solder film of a minute / narrow pitch electronic circuit having an adjacent pitch of 120 μ or less, which is completely impossible by the conventional technology using a molten solder. Providing technology that enables the manufacture of highly reliable semiconductor devices and electronic devices that can be formed and that has no over-volume or bridging with adjacent circuits, and is revolutionary in terms of industrial value. Technology.

Claims (10)

  In a semiconductor device having a large number of electrode pads or leads arranged in a narrow pitch with a width of 120 μm or less and an adjacent pitch of 200 μm or less, the electrode pad or lead surface has tin or solder particles having a size of 0.5 to 40 μm as nuclei, A semiconductor device comprising a semiconductor chip or an interposer formed of a low oxygen concentration solder film having an oxygen concentration of 5 ppm or less.   In a semiconductor device having a large number of electrode pads or leads arranged in a narrow pitch with a width of 120 μm or less and an adjacent pitch of 200 μm or less, tin or solder particles having a size of 0.5 to 40 μmφ on the surface of the plurality of electrode pads or leads Is applied to the surface of the pad or the lead, and the pad or the lead is dissolved in an oil-based solvent having a liquid temperature of 180 to 300 ° C. Contact with an organic compound solution that is stable and contains at least 1% by mass of an organic compound having a carboxyl group (—COOH) or 100% by mass of the organic compound, and then immediately a low oxygen concentration molten solder solution having an oxygen concentration of 5 ppm or less Contact with the organic compound solution and contact the pad or lead surface again. The method of manufacturing a semiconductor device characterized by the formation of bumps or solder film solder.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the electrode pad or the lead of the semiconductor device is brought into contact with the organic compound solution or the low oxygen concentration molten solder solution. An organic fatty acid solution composed of 5 to 80% by mass of any one or more acids and the remaining ester synthetic oil is arranged in the upper layer, and the lower layer contains tin as a main component and one or more of silver, copper, nickel, and germanium. The semiconductor device is immersed in an upper layer liquid and a lower layer liquid in the order of an upper layer liquid and a lower layer liquid in an upper and lower layer liquid composed of a molten solder liquid with an oxygen concentration of 5 ppm or less to which a metal is added. A method for manufacturing a semiconductor device.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the electrode pad or the lead of the semiconductor device is brought into contact with the organic compound solution or the low oxygen concentration molten solder solution. Oxygen concentration of organic fatty acid solution consisting of 5 to 80% by mass of any one or more acids and the remaining ester synthetic oil, and one or more metals of silver, copper, nickel, and germanium containing tin as the main component A manufacturing method of a semiconductor device, wherein a molten solder solution of 5 ppm or less is sprayed from each liquid supply pipe or nozzle and sprayed onto an electrode pad.   5. The method of manufacturing a semiconductor device according to claim 2, 3, and 4, wherein solder particles having a size of 0.5 to 40 [mu] m are provided in a plurality of electrode pads or leads in a semiconductor wafer in which a large number of semiconductor chips are arranged in parallel. After spraying at least one or more and fusing the tin or solder particles to each electrode pad or lead, the upper layer is 1 to 95% by mass of any one or more of palmitic acid or stearic acid having a liquid temperature of 180 to 300 ° C. An organic fatty acid solution composed of the remaining ester synthetic oil, the upper and lower layers made of a molten solder solution having an oxygen concentration of 5 ppm or less, the lower layer of which is mainly composed of tin and containing one or more of silver, copper, nickel, and germanium. It is characterized in that the solder bumps are formed through a process of immersing the wafer in the upper layer liquid and the lower layer liquid in this order and passing the wafer through the upper layer liquid and drawing it out again. A method for manufacturing a semiconductor device.   In an electronic device in which at least a semiconductor device is mounted on a mounting substrate by solder bonding, tin having a size of 0.5 to 40 μmφ bonded to a narrow pitch electrode pad or lead surface having a width of 120 μm or less and an adjacent pitch of 200 μm or less, or A semiconductor device having a solder particle nucleus and a bump or solder film in which a low oxygen concentration solder having an oxygen concentration of 5 ppm or less is fused thereon is mounted on a mounting substrate having electrode pads or leads corresponding to the bump positions of the semiconductor device. An electronic device having a structure in which solder bonding is performed at a predetermined corresponding position.   7. The electronic device according to claim 6, further comprising electrode pads corresponding to bump positions of the semiconductor device and pads or leads corresponding to electrode pads or leads of other semiconductor devices and other electronic components. The semiconductor device and other electronic components are mounted on a mounting substrate coated with a low oxygen concentration solder having an oxygen concentration of 5 ppm or less with a solder particle having a size of 0.5 to 40 μmφ as a nucleus. An electronic device characterized by that.   In an electronic device manufacturing method in which a semiconductor device or an electronic component is solder-bonded to a mounting substrate, the electrode pad or lead exposed on the mounting substrate is cleaned except for the electrode pad or lead portion to be solder-bonded. After spraying tin or solder particles having a size of 0.5 to 40 μmφ on a simple metal surface to disperse at least one of the particles in all the electrode pads or leads, the electrode pads are heated in a heated atmosphere. Alternatively, a first process of adhering the particles to the lead metal surface, and then dissolving the metal surface in an oil-based solvent having a liquid temperature of 180 to 300 ° C. and stable in molecular structure and having at least a carboxyl group (—COOH) Oxygen concentration immediately after contact with an organic compound solution containing 1% by mass or more of the organic compound or 100% by mass of the organic compound alone A second process of forming a solder film on the surface of the electrode pad or lead by contacting with a low oxygen concentration molten solder solution of 5 ppm or less and then immediately contacting with the organic compound solution or the organic compound solution of 100% by mass immediately A method of manufacturing an electronic device, comprising mounting a semiconductor device and other electronic components on a predetermined pad or lead of a mounting substrate on which a solder film is formed through soldering and soldering.   9. The method of manufacturing an electronic device according to claim 8, wherein palmitic acid or stearin having a liquid temperature of 180 to 300 ° C. is used as a method of bringing the mounting substrate into contact with the organic compound solution and the low oxygen concentration molten solder solution in the second process. An organic fatty acid solution composed of 5 to 80% by mass of any one or more acids and the remaining ester synthetic oil is arranged in the upper layer, and the lower layer contains tin as a main component and one or more of silver, copper, nickel, and germanium. Solder film is obtained by immersing the semiconductor device in the upper and lower layers in the order of the upper and lower layers in a molten solder solution with a metal added oxygen concentration of 5 ppm or less, and letting it pass through the upper layer again. Manufacturing an electronic device characterized by mounting a semiconductor device and other electronic components on a predetermined pad or lead of a mounting board formed with solder and soldering Law.   9. The method of manufacturing an electronic device according to claim 8, wherein palmitic acid or stearic acid having a liquid temperature of 180 to 300 ° C. is used as a method of bringing the mounting board into contact with the organic compound solution or the low oxygen concentration molten solder liquid in the second process. Oxygen concentration of organic fatty acid solution consisting of 5 to 80% by mass of any one or more acids and the remaining ester synthetic oil, and one or more metals of silver, copper, nickel, and germanium containing tin as the main component Predetermined pads on the mounting board in which a molten solder solution of 5 ppm or less is sprayed from the respective liquid supply pipes or nozzles and sprayed onto the electrode pads or passed through the overflowing liquid to form a solder film on the pads or leads. Alternatively, a method of manufacturing an electronic device comprising mounting a semiconductor device and other electronic components on a lead and soldering them.

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