JP2006028638A - Method for surface-treating ferroalloy material for lead-free solder, and device for packaging electronic parts having equipment treated with the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treatment method that leads to the manufacture of an equipment member which has more excellent corrosion resistance than a conventional one even if being used in equipment contacting with the melt of a lead-free solder and is inexpensive, and to provide a device for packaging electronic parts, which has the equipment manufactured through using the method. <P>SOLUTION: The method for surface-treating the material or equipment of alloy steel such as stainless steel, which contacts with the melt of the lead-free solder containing 85% or more tin, comprises: hot-dip plating Al or an Al alloy on the surface of the material or the equipment; heating the plated article to diffuse Al or the Al alloy into the alloy steel; simultaneously melting the surplus Al or the Al alloy having deposited on the surface when plated, and removing it by free fall; and further removing flux trapped on the surface during a plating process, with an acidic solution; and forming an Fe-Al intermetallic compound layer or an aluminum-diffused layer having an Al concentration of 13 to 60 atom% on the surface. The device for packaging the electronic parts is provided with the equipment manufactured through using the method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface treatment method for an iron alloy material or equipment that comes into contact with a lead-free solder melt having a tin content of 85% or more, and an electronic component mounting apparatus composed of equipment whose surface is treated by this surface treatment method. More specifically, the present invention relates to a surface treatment method in which an Fe-Al intermetallic compound or aluminum diffusion / penetration layer is provided on the surface of an iron alloy material or equipment, and a mounting apparatus for an electronic component composed of equipment whose surface is treated by this surface treatment method. .

Conventionally used solder, for example, 63 wt% tin-37 wt% lead, has become an environmental problem because lead is harmful to the human body. The movement has been banned.
As a substitute for this lead solder, a lead-free solder, that is, a lead-free solder has been used. Most of these lead-free solders are mainly composed of tin, and typical ones are tin-silver-copper tin-3.5 silver-0.75 copper lead-free solder, tin-copper. Tin-0.7 copper lead-free solder, tin-silver tin-4 silver lead-free solder, tin-zinc tin-9 zinc lead-free solder, trace amounts of elements added to these solders Many lead-free solders that have improved various solder properties are known. Thus, most lead-free solders have a tin content of 85 wt% or more.

These lead-free solders having a tin content of 85 wt% or more are higher in melting point by 30 to 50 ° C. than conventional 63 wt% tin-37 wt% lead (hereinafter referred to as “Sn—Pb solder”). (2) Due to the low lubrication performance of Pb, the equipment that comes in contact with the lead-free solder melt is eroded or worn by high-temperature Sn, and the life of the equipment is significantly shortened. Has occurred.
Note that most of the equipment used for conventional Sn—Pb solder is manufactured from SUS304, which is an austenitic stainless steel.

  On the other hand, when mounting electronic parts, in order to improve solderability, flux is applied to the part to be soldered, but a conventional alcohol solvent, that is, VOC (Volataile Organic Compounds) is used. Recently, a VOC-free flux not containing VOC or a low VOC flux of 10% by weight or less of VOC has come to be used, because the generated flux causes generation of photochemical smog and global warming.

  This VOC-free flux that does not contain VOC or a low VOC flux of 10 wt% or less is usually water as a solvent, but requires a surface cleaning action of the soldered part, so a flux with increased acidity and alkalinity is required. Has come to be used. Equipment that contacts both of these fluxes and the lead-free solder melt has a problem that erosion by the lead-free solder melt is accelerated by the flux.

As materials to be used for the equipment that comes into contact with this lead-free solder melt, (1) SUS316, (2) SUS304 nitriding material, (3) ceramic coating on the surface as described in Patent Document 1 Materials, (4) Ti or Ti alloys, etc. are used or are under consideration.
However, the SUS316 of (1) has a life slightly longer than that of SUS304, which is a material of equipment conventionally used for Sn-Pb solder.

Further, the material obtained by nitriding the surface of SUS304 in (2) has a life of about twice as long as that made of SUS304, but it is still insufficient.
In addition, the ceramic coated product of (3) has a drawback that the lifetime is sufficiently long but the price is high.
Further, the Ti or Ti alloy of (4) has a drawback that it may or may not be effective depending on how it is used (particularly the type of flux used during soldering) and is expensive.

As a material excellent in corrosion resistance against molten tin, steel or stainless steel is processed by an aluminum diffusion coating method, that is, steel or the like is placed in a container together with aluminum-iron alloy powder, and the temperature is 900 to 1000 ° C. Is known in Patent Document 2 in which a heat treatment is performed for about 10 hours and an iron-aluminum alloy layer is provided on the surface of steel or the like.
However, since this method needs to be processed at a high temperature for a long time, there is a problem that equipment joined by welding or the like is significantly deformed to hinder its function and is expensive.

Further, as a method of providing an iron-aluminum alloy layer on the surface of stainless steel or the like, Non-Patent Document 1 also discloses a method in which aluminum is coated by a dipping method or the like and then heated and subjected to a diffusion treatment.
JP 2003-31398 A Japanese Patent Publication No. 48-27056 “Metal Surface Technology Handbook” edited by the Metal Surface Technology Association, November 30, 1951, published by Nikkan Kogyo Shimbun, pages 1163 to 1167

  The present invention has corrosion resistance such as erosion resistance superior to materials and equipment obtained by nitriding SUS304 even when used in equipment that comes into contact with a lead-free solder melt having a tin content of 85% or more, and is inexpensive. It is an object of the present invention to provide a surface treatment method capable of manufacturing materials and equipment, and an electronic component mounting apparatus having equipment that is superior in corrosion resistance and cheaper than equipment obtained by nitriding SUS304. .

  In order to solve the above problems, the present inventors have corrosion resistance such as erosion resistance superior to a nitrided device even when used in a device that contacts a lead-free solder melt having a tin content of 85% or more. We have been eagerly researching surface treatment methods that can produce materials and equipment. We have hot-plated aluminum or aluminum alloys on the surface of iron alloys such as steel, stainless steel, and cast iron, and then heated them to aluminum or aluminum alloys. At the same time, the aluminum or aluminum alloy adhering excessively at the time of plating is removed by melting (removal by natural dropping, etc.), and an Fe—Al intermetallic compound layer or aluminum diffusion / penetration layer having an aluminum concentration of 13 to 60 at% on the surface Use a formed stainless steel, steel, cast iron, or other iron alloy to contact a lead-free solder melt with a tin content of 85% or more When configuring the device, obtain a knowledge that life than those produced with materials nitrided stainless steel is much longer.

  Furthermore, if aluminum is mixed into lead-free solder with a tin content of 85% or more, an intermetallic compound is formed at the solder joint, which makes the joint brittle, so aluminum must not be mixed in. It was found that if the flux adhered during plating is left attached, the solder melt will be contaminated and the strength and chemical properties of the joint will be reduced. .

In addition, if the flux is removed with an acid solution and washed with water, a very small amount of aluminum residue reacts with nitric acid to form aluminum nitrate, which remains adhered to the surface as sludge, and the tin content is 85% or more. When contacted with lead-free solder, Ag and Cu in this lead-free solder form an alloy and intermetallic compound, which increases dross in the solder melt, and this dross is interposed in the solder joint and mechanically It is preferable to remove this sludge because there is a risk of deteriorating chemical properties.To remove this sludge, shot peening can be used to remove the sludge sufficiently, and the residual stress distribution on the outermost surface. Will become uniform compressive stress, and stain-like discoloration that may be caused by variation in residual stress distribution due to contact with lead-free solder melt Knowledge was obtained such that there is an effect that Kunar.
The present invention has been made based on these findings.

  That is, the present invention provides a plating layer and a Fe-Al intermetallic compound layer or an aluminum diffusion / penetration layer by subjecting a surface of an iron alloy material or equipment such as stainless steel, special steel, cast iron or the like to aluminum or aluminum alloy. It is formed and heated to diffuse aluminum or aluminum alloy, and at the same time, excess aluminum or aluminum alloy adhering at the time of plating is melted and removed by natural dropping or the like, and the flux adhering at the time of plating is removed with an acid solution to remove the surface. A surface of a material or device that comes into contact with a lead-free solder melt with a tin content of 85% or more, wherein an Fe—Al intermetallic compound layer or aluminum diffusion / penetration layer having an aluminum concentration of 13 to 60 at% is formed It is a processing method.

  Furthermore, the present invention removes the flux adhering at the time of plating with an acid solution, and then performs shot peening to remove oxidized sludge such as aluminum or an aluminum alloy, so that the surface is Fe-Al having an aluminum concentration of 13 to 60 at%. An intermetallic compound layer or an aluminum diffusion layer is a surface treatment method for a material or device that contacts a lead-free solder melt having a tin content of 85% or more.

  Further, the present invention provides a stainless steel device in which a device in contact with a lead-free solder melt having a tin content of 85% or more has a Fe—Al intermetallic compound layer or an aluminum diffusion layer having an aluminum concentration of 13 to 60 at% on the surface. An electronic component mounting apparatus comprising an iron alloy such as steel, special steel, or cast iron.

  In addition, the present invention provides a lead-free solder melt having a tin content of 85% or more and an alcohol solvent that does not contain an alcohol solvent or a flux of a low alcohol solvent having a content of 10 wt% or less. An electronic component mounting apparatus comprising: an iron alloy such as stainless steel, special steel, cast iron or the like having a Fe-Al intermetallic compound of -60 at% or an aluminum diffusion layer.

  Further, according to the present invention, there is provided an electronic component mounting apparatus that contacts the lead-free solder melt of 85% or more as one of a solder bath, a chamber body, a blower body, a heater, a pump, and a solder flow path. Or it is characterized by being two or more.

In the present invention, the “apparatus” means a material made by processing a material, and includes a member made by processing the material.
Furthermore, in the present invention, the “configuration” of “… consisting of an iron alloy ...” includes an Fe—Al metal having an aluminum concentration of 13 to 60 at% on the surface of the material before the device is manufactured. When an intermetallic compound layer or an aluminum diffusion / penetration layer is formed and an apparatus is manufactured using this material, after the apparatus is manufactured, the surface of the apparatus is Fe-Al intermetallic compound or aluminum diffusion / infiltrating with an aluminum concentration of 13 to 60 at%. This includes the case where a layer is provided.

  In the present invention, the “Fe—Al intermetallic compound layer or aluminum diffusion / penetration layer” means not only the Fe—Al intermetallic compound layer but also the aluminum diffusion / penetration layer, as well as the Fe—Al intermetallic compound. Including those having both a layer and an aluminum diffusion / permeation layer, and those containing an intermetallic compound of Al with another metal other than Fe, such as a Cr-Al intermetallic compound and a Ni-Al intermetallic compound It is not something that excludes. Further, it is not excluded that the outermost surface of these layers has the treatment of the present invention or a naturally produced passivated film.

  (1) The surface treatment method of the present invention is a lead-free solder having a tin content of 85% or more (hereinafter referred to as “lead-free solder”) on the surface of an iron alloy material such as stainless steel, special steel, cast iron, or equipment. ) Fe—Al intermetallic compound layer or aluminum diffusion permeation layer (hereinafter referred to as “Fe—Al intermetallic compound layer or aluminum diffusion permeation”) having an aluminum concentration of 13 to 60 at% excellent in corrosion (erosion) and wear against the melt. Layer ") can be formed at low cost, and the flux adhering during plating is sufficiently removed with an acid solution, so that the lead-free solder melt is contaminated, and the mechanical and chemical components of the solder joints The characteristic is not deteriorated.

  (2) The flux adhering during plating of the present invention is removed with an acid solution, and then shot peening is sufficient to remove the sludge, and the residual stress distribution on the outermost surface becomes a uniform compressive stress, leading to lead-free solder melting. Since it has the effect of eliminating spot-like discoloration that may be caused by variations in the residual stress distribution due to contact with the liquid, aluminum and other materials do not contaminate the lead-free solder melt. Since the characteristics are not deteriorated and the surface is stable, it is more excellent against erosion, wear, etc. due to a lead-free solder melt.

  (3) The electronic component mounting apparatus of the present invention does not include lead-free solder melt or lead-free solder melt and alcohol-based solvent flux of 10 wt% or less (hereinafter collectively referred to as both). Lead-free solder melt because the device in contact with the "low VOC flux" is made of an iron-alloy such as stainless steel or steel having a Fe-Al intermetallic compound or an aluminum diffusion layer on its surface. It is excellent in erosion and wear due to, and is inexpensive.

First, matters common to the present invention will be described.
The iron alloys processed by the surface treatment method of the present invention or used in the electronic component mounting apparatus of the present invention are ordinary steel, stainless steel, special steel, cast iron, etc., but in many members, austenitic stainless steel SUS304, SUS316, etc. are preferable because they have excellent corrosion resistance. However, the solder tank may be cast iron, the blower body may be carbon steel, and the heater cover (sheath) is preferably a carbon steel pipe. Since the heater cover (sheath) undergoes a thermal cycle and is frequently expanded and contracted, a carbon steel pipe having a smaller coefficient of linear expansion than austenitic stainless steel and excellent in thermal fatigue resistance is preferable.

In the present invention, the Fe—Al intermetallic compound is Fe ₃ Al, Fe ₂ Al ₅ , Fe ₃ Al ₂ or the like. Most of the Fe—Al intermetallic compound or aluminum diffusion / penetration layer formed by the treatment by the surface treatment method of the present invention is an Fe—Al intermetallic compound having an aluminum concentration of 13 to 60 at%. Is slight. Most of the Fe—Al intermetallic compounds are Fe ₂ Al ₅ (η phase).

  Further, in the present invention, the aluminum concentration of the Fe-Al intermetallic compound or the aluminum diffusion layer is limited to 13 to 60 at% when the aluminum concentration is less than 13 at%, the lead-free solder melt or the lead-free solder This is because erosion resistance, wear resistance, etc. are not sufficient with respect to the melt and low VOC flux. If it exceeds 60 at%, pure aluminum tends to appear on the surface and may be dissolved in the lead-free solder melt. Because.

Next, the surface treatment method of the present invention will be described.
The pretreatment method of the iron alloy processed by the hot dipping of the present invention may be a method performed by a normal hot dipping method of aluminum or aluminum alloy. For example, shot blasting is performed, and degreasing, water washing, acid washing, water washing, hot water washing preheating and flux application (floating on the surface of a hot dipping bath) may be performed in this order with a strong alkaline solution.

In this pretreatment method, if shot blasting is performed before degreasing with a strong alkaline solution, the surface of the material itself becomes inhomogeneous due to inhomogeneous surface properties and secondary processing (casting, pressing, machining, welding, etc.) The surface is increased by homogenizing the properties, cleaning the surface, and forming irregularities (skin texture) on the surface, and the plating properties of the molten aluminum before the Fe-Al intermetallic compound are good. Become. In particular, when an Fe—Al intermetallic compound layer is formed on cast iron, the surface oxide layer, the adhering mold binder, and the cast sand buried in the surface are removed and cleaned, which is effective. It is preferable to use sand, ceramic, and crushed glass that are machinable as the yacht blasting material, and at a spraying pressure of 0.5 to 10 kg / cm ² until the surface roughness becomes uniform.

In addition, if preheating is performed before hot dipping, the residual stress of materials and processing (pressing, machining, welding, etc.) is released, and deformation due to rapid heating by dipping in a hot dipping bath (expansion due to differences in wall thickness) The deformation due to the difference can be prevented. This preheating is performed by heating to 600 to 800 ° C. while performing stress relief annealing in a non-oxidizing atmosphere furnace, or after heating to 200 to 300 ° C., and further holding immediately above the aluminum hot dipping bath for 5 to 90 minutes, It is preferable to heat at 300-700 degreeC.
The apparatus used for hot dipping may be a normal apparatus for hot dipping aluminum or an aluminum alloy.

  The hot dip plating material used in the surface treatment method of the present invention is aluminum or an aluminum alloy. The aluminum alloy is an Al-12 wt% Si alloy, an Al-Si-Mg alloy, and 0.2 to 2 wt% Be. Or an alloy containing 0.1 to 1.5 wt% of Mn. The aluminum alloy containing Be has an effect of suppressing the generation of dross that floats on the surface of the plating bath, and is effective when plating is performed in the air. In addition, the alloy containing Mn has an effect of suppressing peeling from the interface by forming an intermetallic compound layer having an anchor effect with a dimple shape (wave having a small cross section) at the interface with the base material.

  The hot dip plating temperature is suitably 30 to 50 ° C. higher than the melting point of the aluminum or aluminum alloy of the material to be plated. For example, in the case of an Al-12 wt% Si alloy, the hot dipping temperature is 650 to 700 ° C. If the hot dipping temperature is too high, dross generation increases and intermetallic compounds are not formed uniformly, so the temperature is preferably as low as possible. Further, if the temperature is too high, if the covered material is stainless steel, the chromium carbide is coarsened and the corrosion resistance, toughness and the like are lowered, so the lower one is preferable.

The immersion time in the hot dipping bath varies depending on the plating method of aluminum or aluminum alloy.
In the case of a method in which the material to be plated is heated in a H ₂ , H ₂ —N ₂ reducing atmosphere, plating can be performed in 1 to 2 seconds.
In the case of the flux system, the reaction time is not reached unless the reaction time for activating the surface of the material to be plated and the temperature of the plating melt is reached.

In the case of the displacement plating method, it does not react unless the plating film is dissolved in the hot dipping bath, so that it varies depending on the preheating temperature and mass.
If the immersion time is too long, the material to be plated is eroded by the molten aluminum, and is dissolved in the molten aluminum, the thickness of the material to be plated is reduced, and the composition of the plating bath is changed. preferable. Therefore, the immersion time in the hot dipping bath is appropriately 2 seconds to 20 minutes.
The immersion in the hot dipping bath is preferably performed twice or more. This is because it may not be possible to uniformly plate the entire surface at one time.

  The cooling rate after hot dipping may be fast or slow in the present invention. In the case of general hot-dip aluminum plating, quenching is performed to suppress the formation of an intermetallic compound layer at the interface between the material to be plated and the plating layer (because the intermetallic compound layer is brittle). This is because the intermetallic compound layer is utilized.

  Heating after hot dipping is performed by diffusing aluminum or aluminum alloy to increase the Fe-Al intermetallic compound or aluminum diffusion permeation layer, and at the same time melting and removing the aluminum or aluminum alloy adhering excessively during plating Because. The heating temperature is suitably 700 to 900 ° C. and may be heated in the atmosphere. The heating time is about 1 to 5 hours.

The reason why the flux adhering at the time of plating after hot-dip plating is removed with an acid solution is that the flux contaminates the lead-free solder melt, and the flux enters the joint and reduces the strength and chemical properties of the joint. . In order to remove the flux, pickling may be performed with a 3 to 6 wt% nitric acid solution or the like.
Thereafter, it can be completed by washing with water, washing with water and drying, but if necessary, a step of treating the surface by the following shot peening can be added.

The reason why the flux adhering at the time of plating is removed with an acid solution, followed by washing with water and hot water, and then shot peening is to remove sludge and to make the residual stress distribution on the outermost surface uniform compressive stress. Shot peening removes the sludge sufficiently and eliminates the variation in the residual stress distribution on the outermost surface that occurs when the material to be plated comes into contact with the lead-free solder melt. This is because no discoloration occurs.
This shot peening is suitably performed at a blasting material particle size of 100 to 600 mesh and a projection pressure of 0.3 to 10 kg / cm ² .

Next, a description will be given of a device that comes into contact with the lead-free solder melt or the lead-free solder melt and the low VOC flux of the electronic component mounting apparatus.
FIG. 3 is an explanatory view showing a state where an electronic component is mounted on a printed wiring board and soldered, and FIG. 4 is a perspective view of an example of a soldering apparatus for an electronic component mounting apparatus to which the present invention is applied. 4 is a cross-sectional view taken along the line AA in FIG. 4, FIG. 6 is a perspective view of another example of the soldering device for the electronic component mounting apparatus to which the present invention is applied, and FIG. 7 is a cross-sectional view taken along the line BB in FIG. .

First, a part for soldering an electronic component to a printed wiring board using lead-free solder by the electronic component mounting apparatus of the present invention and a soldering method will be described with reference to FIG.
In the case of a lead-type electronic component, the lead of the lead-type electronic component is located in a hole in the printed wiring board (a copper foil portion called a land around the back of the hole is connected to the circuit). Insert the terminal from above, and in the case of chip-type electronic components, place the terminal electrode on the land of the printed wiring board and temporarily bond it with an adhesive, and the lead terminal and land, and the terminal electrode and land are in the solder bath. The printed wiring board mounted with electronic components is conveyed so as to come into contact with the jet wave of the lead-free solder melt coming out from the blower opening (see FIG. 4), and the lead terminals and lands as shown in FIG. In this method, solder fillets are formed on terminal electrodes and lands for soldering.

Next, an example of a soldering apparatus for an electronic component mounting apparatus will be described with reference to FIGS.
A soldering apparatus 1 for mounting an electronic component according to the present invention is fixed to a solder tank 2 containing a lead-free solder melt 5, a chamber body 3 provided in the upper part of the solder tank 2, and an upper part of the chamber body 3. The blower body 4, the electromagnetic pump 6 that is provided in the solder tank 2 and feeds the lead-free solder melt 5 into the chamber body 3, the heater 7 that heats the lead-free solder melt 5, and the outside of the solder tank 2 The control device 8 for the electromagnetic pump 6 provided in the control device 9, the control device 9 for controlling the heater 7, and the like.

  The solder tank 2 is fixed by a caging 10 and contains a lead-free solder melt 5. A chamber body 3 and the like are installed therein, and the solder tank 2 is made of cast iron or the like. Since the inner surface of the solder bath 2 is in contact with the lead-free solder melt 5 and may be further in contact with the low VOC flux, an Fe-Al intermetallic compound layer or an aluminum diffusion / penetration layer is formed on the surface. ing.

  In addition, when FIG. 5 is seen, although it seems that the solder tank 2 is divided into up and down, things like the partition seen in the middle support the chamber body 3 on the upper side, and support the electromagnetic pump 6 on the lower side. The suspension member 11 is configured such that the lead-free solder melt 5 can freely move up and down (moves as indicated by an arrow during use).

  The chamber body 3 provided in the upper part in the solder tank 2 is fixed to the upper edge of the solder tank 2 with a screw 25, and is fixed to a suspension member 11 provided with a handle 12 in the upper part. The chamber body 3 is provided with a guide plate 13 therein, and the blower body 4 is fixed at the upper part by a screw 15 protected by a sleeve 14, and the discharge port 16 of the electromagnetic pump 6 is fixed at the lower part. The lead-free solder melt 5 heated by the heater 7 and at a predetermined temperature is fed by the electromagnetic pump 6 so that the lead-free solder melt 5 is supplied to the blower body 4 fixed on the top. It is what has become.

The chamber body 3 is made of austenitic stainless steel SUS316 or the like, and both inner and outer surfaces thereof are in contact with the lead-free solder melt 5 and may be in contact with a low VOC flux. An Fe—Al intermetallic compound layer or an aluminum diffusion layer is formed.
Further, since the suspension member 11 and the sleeve 14 are also in contact with the lead-free solder melt 5 and may be in contact with the low VOC flux, an Fe-Al intermetallic compound or an aluminum diffusion / penetration layer is formed on the surface thereof. Yes.

  The blower body 4 is fixed to the upper part of the chamber body 3 with a screw 15 protected by a sleeve 14, and the blower body 17 is provided with a blower port 17 that is narrow in the vertical direction and long in the horizontal direction. The lead-free solder melt 5 supplied from 3 forms a jet wave 18 from the blowing port 17 and flows out into the solder bath 2.

  This blower body 4 is made of carbon steel or the like, and both inner and outer surfaces are in contact with the lead-free solder melt 5 and may further be in contact with a low VOC flux. An intermetallic compound layer or an aluminum diffusion layer is formed.

  The electromagnetic pump 6 which is fixed to the lower side of the suspension member 11 with a fixing screw 29 and feeds the lead-free solder melt 5 into the chamber body 3 has an outer core and a coil 19, and an internal portion having a grip portion 23 at the top. It consists of a core 20, a pipe 24 for electric wire cover for energizing the coil, and the outer core, the coil 19, and the inner core 20 are provided with covers 21 and 22 so as not to directly contact the lead-free solder melt 5. It has been.

  In the electromagnetic pump 6, electricity supplied from a power source 26 provided outside the solder bath 2 is controlled by the control device 8, and the suction between the outer core and the coil 19 and the inner core 20 is performed below. The lead-free solder melt 5 is sucked from the port 27, passes between them, is supplied to the lower portion of the chamber body 3 from the discharge port 16 coupled to the chamber body 3, is distributed by the guide plate 13, and is blown out A jet wave 18 is produced from the air outlet 17 and flows out.

  The outer core of the electromagnetic pump 5 and the covers 19 and 22 of the coil 19 and the inner core 20 and the pipe 24 are made of SUS316 or the like, and their outer surfaces are in contact with the lead-free solder melt 5, Since it may be in contact with the low VOC flux, an Fe—Al intermetallic compound layer or an aluminum diffusion / penetration layer is formed on the surface thereof. The fixing screw 29 is similarly processed.

The heater 7 provided in the lower part in the solder tank 2 is for heating the lead-free solder melt 5 to a predetermined temperature, and a cover (sheath) 28 is provided so as not to contact the lead-free solder melt 5 directly. Is provided.
The heater 7 is heated by being supplied with electricity from a power source 26 provided outside the solder bath 2, and measures the temperature of the lead-free solder melt 5 with a sensor 30 covered with a cover 31. The temperature is controlled by controlling the electricity supplied from the power source 26 by the temperature control root device 9 based on the measured value.

The cover (sheath) 28 of the heater 7 is made of carbon steel or the like, and the outer surface thereof is in contact with the lead-free solder melt 5 and may be further in contact with the low VOC flux. An Fe—Al intermetallic compound layer or an aluminum diffusion layer is formed.
Further, since the outer surface of the cover 31 of the sensor 30 is also in contact with the lead-free solder melt 5 and further in contact with the low VOC flux, an Fe—Al intermetallic compound layer or an aluminum diffusion / penetration layer is formed on the surface. Is formed.

As described above, the soldering apparatus 1 of the electronic component mounting apparatus according to the present invention is in contact with the lead-free solder melt 5 and may further be in contact with the low VOC flux. Alternatively, since the aluminum diffusion / penetration layer is formed, the aluminum diffusion / penetration layer has excellent corrosion resistance such as erosion resistance, wear resistance, etc. with respect to the lead-free solder melt.
Reference numeral 38 in the figure is a dross.

Next, another example of the soldering apparatus of the electronic component mounting apparatus will be described with reference to FIGS.
A soldering apparatus 1 for an electronic component mounting apparatus according to the present invention uses a rotary pump 32, and includes a solder tank 2 for storing a lead-free solder melt 5, and a chamber body provided at an upper portion in the solder tank 2. 3, blower body 4 fixed to the upper part of chamber body 3, rotary pump 32 for feeding lead-free solder melt 5 into chamber body 3, heater 7 for heating lead-free solder melt 5, solder bath 2 includes a control device (not shown) for the rotary pump 32 provided outside 2, a control root device 9 for controlling the heater 7, and the like.

  The soldering apparatus 1 for the electronic component mounting apparatus is substantially the same as the example of the soldering apparatus 1 for the electronic component mounting apparatus described above. A description will be given of the rotary pump 32 that is different from each other.

  The rotary pump 32 includes a motor 33 installed on a pedestal 36 fixed on the solder bath 2, a rotary shaft 34 driven by the motor 33, and an impeller 35 fixed to the rotary shaft 34 and rotating. It has become. The lead-free solder melt 5 heated to a predetermined temperature by the heater 7 is sucked from the lower suction port 27, supplied to the chamber body 3 from the discharge port 16 provided on the lateral side, and distributed by the guide plate 13. The flow is rectified by the perforated plate 37, and the jet wave 18 is made to flow out from the blowing port 17 of the blowing body 4.

  In the rotary pump 32, the surfaces of the rotary shaft 34 and the impeller 35 are in contact with the lead-free solder melt 5 and may be further in contact with the low VOC flux. A diffusion penetration layer is formed.

  A JIS SUS316 stainless steel plate with a thickness of 3 mm is used as a material to be plated. As shown in FIG. 1, this material is shot blasted using a glass bead of 120 mesh as a pretreatment, and degreased. Washing, pickling, washing and drying in this order, preheating for 60 minutes at 300 ° C, and immersing in a 700 ° C aluminum hot dipping bath with added stainless steel flux for 5 minutes to eliminate processing irregularities It was further immersed for 5 minutes, and the excess adhering aluminum was shaken off and cooled in the air. Thereafter, the material to be plated was placed in an atmospheric furnace at 830 ° C. and heated for 3 hours to thermally diffuse the aluminum adhering to the surface to the material to be plated, and the molten aluminum adhering to the surface was naturally dropped and cooled. Further, the flux adhering at the time of plating was removed by dipping in a 5% nitric acid solution, followed by washing with water, washing with hot water and drying to obtain a test piece 1 of the present invention.

When the concentration of aluminum in the surface layer of the test piece 1 of the present invention was measured, the concentration of aluminum in the intermetallic compound layer and diffusion diffusion layer was about 54.7 at%, and most of the aluminum was composed of the intermetallic compound. It was Fe ₂ Al ₅ (η phase). The thickness of the intermetallic compound layer and the diffusion / penetration layer was 15 μm at the thin portion and 25 μm at the thick portion.

  A JIS SUS316 stainless steel plate with a thickness of 3 mm is used as a material to be plated, and as shown in FIG. 2, this material to be plated is shot blasted using a glass bead glass with a particle size of 100 mesh as a pretreatment for plating. Degreasing, rinsing, pickling, rinsing and drying are performed in this order, preheating at 300 ° C. for 60 minutes, and immersed in a 700 ° C. aluminum hot dipping bath to which stainless steel flux has been added for 5 minutes to eliminate uneven processing. In order to eliminate it, it was further immersed for 5 minutes, and the excess adhering aluminum was shaken off and cooled in the atmosphere. Thereafter, the material to be plated is put in an atmospheric furnace at 710 ° C. and heated for 3 hours to thermally diffuse the aluminum adhering to the surface to the material to be plated, and the molten aluminum adhering to the surface is naturally dropped, air-cooled, and washed with hot water. . Further, the flux adhering to the surface is removed by dipping in a 5 wt% nitric acid solution, washed with water, washed with hot water and dried (the same as in Example 1 up to this point), and a glass bead glass with a particle size of 240 mesh. Using shot peening. Thereafter, it was washed with water, washed with hot water and dried to obtain a test piece 2 of the present invention.

When the concentration of aluminum in the surface layer of the test piece 2 of the present invention was measured, the concentration of aluminum in the intermetallic compound layer and diffusion diffusion layer was about 54.7 at%, and most of the aluminum was composed of the intermetallic compound. It was Fe ₂ Al ₅ (η phase). Further, the thickness of the intermetallic compound layer and the diffusion / penetration layer was 15 μm at the thin portion and 25 μm at the thick portion, the surface was smooth, and even when the surface was rubbed with tissue paper, oxidized sludge and the like did not adhere to the tissue paper. .

  A test piece 3 according to the present invention was prepared in the same manner as in Example 2 except that a JIS SUS304 stainless steel plate having a thickness of 3 mm was used as the material to be plated.

When the concentration of aluminum in the surface layer of the test piece 3 of the present invention was measured, the concentration of aluminum in the intermetallic compound layer and diffusion diffusion layer was about 54.7 at%, and most of the aluminum was composed of the intermetallic compound. It was Fe ₂ Al ₅ (η phase). Further, the thickness of the intermetallic compound layer and the diffusion / penetration layer was 15 μm at the thin portion and 25 μm at the thick portion, the surface was smooth, and even when the surface was rubbed with tissue paper, oxidized sludge and the like did not adhere to the tissue paper. .

[Erosion test]
Test pieces 1, 2 and 3 of the present invention, untreated SUS304 stainless steel plate with a thickness of 3 mm (Comparative Example 1), untreated SUS316 stainless steel plate with a thickness of 3 mm (Comparative Example 2) ), SUS304 stainless steel plate with a thickness of 3 mm was nitrided under reduced pressure, and a test piece (Comparative Example 3) provided with an oxide layer of 2 to 3 μm on the surface and a stainless steel plate with a thickness of 3 mm of SUS316 were passivated on the surface. A test piece (Comparative Example 4) subjected to nitriding treatment with a chemical film was immersed in a 400 ° C. lead-free solder (Sn-3.0 wt% Ag-0.5 wt% Cu) melt 6 times per minute It moved up and down, the weight of each test piece was measured every time shown in FIG. 8, and the erosion state was represented by the weight loss rate in FIG.

  According to these results, the test piece of Comparative Example 1 (no treatment) had a weight loss rate of -3.2% in 500 hours, and the test piece of Comparative Example 2 (no treatment) had a weight loss rate of -1. The test piece of 1% and Comparative Example 3 (special nitriding treatment) had a weight loss rate of −0.6% after 3700 hours, and the test piece of Comparative Example 4 (special nitriding treatment) had a weight loss rate of −0 after 1400 hours. It was 4% and was considerably eroded. On the other hand, the test piece 1 of the present invention has a weight loss rate of + 0.11% at 1,064 hours, the test piece 2 of the present invention has a weight loss rate of + 0.21% at 4,200 hours, The test piece 3 of the present invention had a weight loss rate of + 0.28% after 5,300 hours, and was slightly increased without any weight loss due to erosion.

The surface state after 1064 hours of test piece 1 of the present invention is shown in FIG. 9, the surface state of test piece 2 of the present invention after 4200 hours is shown in FIG. 10, and test piece 3 of the present invention is 4000 hours later. FIG. 11 shows the subsequent surface state, FIG. 12 shows the surface state of the test piece of Comparative Example 1 after 920 hours, and FIG. 13 shows the surface state of the test piece of Comparative Example 2 after 920 hours. FIG. 14 shows the surface state of the test piece of Comparative Example 3 after 3700 hours, and FIG. 15 shows the surface state of the test piece of Comparative Example 4 after 1400 hours. The white parts of these pictures are eroded parts.
From these photographs, it can be seen that the test pieces of Comparative Examples 1 to 4 are considerably eroded. However, it can be seen that the test pieces 1 to 3 of the present invention are hardly eroded after 1064 hours, 4200 hours, or 4000 hours.

  Using the test pieces 2 and 3 of the present invention and the test pieces of Comparative Examples 1 and 2, and using the same lead-free solder melt as in the above erosion test, the test piece was moved up and down 6 times per minute, and the VOC free flux was When 20 ml per 1000 hours was added in the vicinity of the contact between the molten lead-free solder and the test piece, the test piece of Comparative Example 1 and the test piece of Comparative Example 2 were also discolored and corroded at the part not in contact with the molten lead-free solder. However, the test pieces 2 and 3 of the present invention had no discoloration and no corrosion.

  The solder bath is made of cast iron (FCD material), the heater cover (sheath) is made of carbon steel pipe (STKM material), and these are treated in the same manner as the above test piece 2 and the Fe—Al intermetallic compound layer is formed on the surface. Alternatively, an aluminum diffusion penetration layer was formed. When these solder bath and heater cover were used as the solder bath and heater cover in the above erosion test, no erosion was observed after 4500 hours.

  INDUSTRIAL APPLICABILITY The present invention is applied to an electronic component mounting apparatus or the like that is indispensable for soldering an electronic component to a printed wiring board, and is a molten lead-free solder having a high erosion property or a low VOC having a high corrosion property. Since it has high erosion resistance and corrosion resistance with respect to the flux, the method to be carried out is easy, and the manufactured materials and equipment are inexpensive, it can be used sufficiently.

It is explanatory drawing which shows an example of the implementation method of this invention. It is explanatory drawing which shows the other example of the implementation method of this invention. It is explanatory drawing which shows the place which mounted | worn and soldered the electronic component to the printed wiring board. It is a perspective view of an example of the soldering apparatus of the mounting device of the electronic component to which this invention is applied. It is AA sectional drawing of FIG. It is a perspective view of the other example of the soldering apparatus of the mounting device of the electronic component to which this invention is applied. It is BB sectional drawing of FIG. It is a craft which shows the result of having done the erosion test of the test piece of Examples 1-3 of this invention, and Comparative Examples 1-4. It is a drawing-substituting photograph of the test piece 1 of the present invention subjected to an erosion test. It is a drawing-substituting photograph of the test piece 2 of the present invention subjected to an erosion test. It is a drawing-substituting photograph of the test piece 3 of the present invention subjected to an erosion test. It is the drawing substitute photograph of the test piece of the comparative example 1 which did the erosion test. It is the drawing substitute photograph of the test piece of the comparative example 2 which did the erosion test. It is the drawing substitute photograph of the test piece of the comparative example 3 which did the erosion test. It is a drawing substitute photograph of the test piece of Comparative Example 4 subjected to the erosion test.

Explanation of symbols

1 Soldering device for electronic component mounting equipment 2 Solder bath 2
3 Chamber body 4 Air outlet body
5 Lead-free solder melt 6 Electromagnetic pump 7 Heater 8 Electromagnetic pump control device 9 Heater control device
10 Casing
11 Hanging member
12 Handle
13 Information board
14 sleeve
15 screw
16 Discharge port
17 mouth
18 Jet wave
19 Outer core and coil
20 inner core
21 Cover of outer core and coil
22 Inner core cover
23 Grip part
24 pipe
25 Fixing screw
26 Power supply
27 Suction mouth
28 Heater cover (sheath)
29 Fixing screw
30 sensors
31 Sensor cover
32 Rotary pump
33 motor
34 Rotation axis
35 impeller
36 Suction mouth
37 perforated plate
38 Dross

Claims (9)

  When the surface of an iron alloy material or equipment is hot-plated with aluminum or aluminum alloy to form a plating layer and an Fe-Al intermetallic compound or aluminum diffusion / penetration layer, and this is heated to diffuse aluminum or the aluminum alloy At the same time, the excessively adhered aluminum or aluminum alloy is removed by melting, and the flux adhering at the time of plating is removed with an acid solution, and the Fe-Al intermetallic compound or aluminum diffusion permeation layer having an aluminum concentration of 13 to 60 at% on the surface. A surface treatment method for an iron alloy material or device that contacts a lead-free solder melt having a tin content of 85% or more.   When the surface of an iron alloy material or equipment is hot-plated with aluminum or aluminum alloy to form a plating layer and an Fe-Al intermetallic compound or aluminum diffusion / penetration layer, and this is heated to diffuse aluminum or the aluminum alloy At the same time, the excess aluminum or aluminum alloy is removed by melting, the flux adhering during plating is removed with an acid solution, and then shot peening is performed to remove aluminum or aluminum alloy and iron oxide sludge on the surface. A Fe-Al intermetallic compound having an aluminum concentration of 13 to 60 at% or an aluminum diffusion / penetration layer formed on the surface, or an iron alloy material in contact with a lead-free solder melt having a tin content of 85% or more, or Surface treatment method for equipment.   3. The surface treatment method for a material or equipment that contacts a lead-free solder melt having a tin content of 85% or more according to claim 1 or 2, wherein the iron alloy is stainless steel or cast iron.   A device that comes into contact with a lead-free solder melt having a tin content of 85% or more is composed of an iron alloy having an Fe-Al intermetallic compound layer or an aluminum diffusion layer having an aluminum concentration of 13 to 60 at% on the surface. An electronic component mounting apparatus characterized by that.   The device that contacts the lead-free solder melt having a tin content of 85% or more is one or more of a solder bath, a chamber body, a blower body, a heater, a pump, and a solder flow path. The electronic component mounting apparatus according to claim 4, wherein:   5. The electronic component mounting apparatus according to claim 4, wherein the iron alloy is stainless steel or cast iron.   A lead-free solder melt with a tin content of 85% or more and an apparatus that does not contain an alcoholic solvent or a flux of a low alcoholic solvent with a content of 10 wt% or less is Fe- having an aluminum concentration of 13 to 60 at% on the surface. An electronic component mounting apparatus comprising an iron alloy having an Al intermetallic compound layer or an aluminum diffusion layer.   The lead-free solder melt having a tin content of 85% or more and a device that does not contain an alcohol solvent or a flux of a low alcohol solvent having a content of 10 wt% or less are a solder bath, a chamber body, a blow body, and a heater. The electronic component mounting apparatus according to claim 7, wherein the electronic component mounting apparatus is one or more of a pump and a solder flow path. 8. The electronic component mounting apparatus according to claim 7, wherein the iron alloy is stainless steel or cast iron.

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