JP2001212694A - Wirelike solder and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wirelike solder with a flux which is formed by processed wires and is thoroughly made at a low cost, though a reformed prepared- composition is delicate when a lead-free solder base alloy, for example, Sn-Ag series of a solder is reformed by adding Bi. SOLUTION: Prepared solder materials, in which Bi is added into a solder base alloy, are divided to composition materials having different compositions. A part of the composition materials are formed to a wire n by a wire drawing, and other part of the composition materials are formed to a wire m by a rotary in-liquid spinning method in which a jet-stream of a molten solder of the composition materials is injected to a rotary cooling liquid stratum for spinning. These wires are then lumped together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear solder and a method for manufacturing the same.

[0002]

2. Description of the Related Art A flux-shaped linear solder having a diameter of about 1 to 1.2 mm is used for repairing or retrofitting an electronic component after mounting it on a printed circuit board by a flow method or a reflow method. Have been. Conventionally, Sn-Pb-based solder has been used as the above-mentioned solder. However, the harmfulness of lead eluted from waste home appliances to the human body has been a problem, and lead-free or reduced lead has been demanded. ing.

[0003]

As such a lead-free solder, Sn-Ag based solder is known. However, in this solder, the basic properties of the solder, especially the wettability, are lower than those of Sn-Pb based solder. Inferior, modification is required. To improve the wettability, the addition of Bi is effective. However, the addition of Bi inevitably makes it brittle, making continuous drawing difficult, and the linear shape having a wire diameter of about 1 mm required for the above correction soldering. It becomes extremely difficult to draw solder.

The present applicant has proposed a method of producing a solder wire by spinning in a rotating liquid, that is, cooling a molten solder jet injected from a nozzle into a cooling liquid layer formed and held on the inner peripheral surface of a rotating drum by centrifugal force. We have already developed a method in which the liquid is injected at the same speed and in the same direction as the peripheral speed of the liquid layer, and this liquid layer incident jet is quenched and solidified in the cooling liquid layer to spin. In the spinning process, the jet in the space from the nozzle to the coolant layer is formed into a circular cross section by maintaining the circular shape of the nozzle by the surface tension of the molten metal, and the jet having the circular cross section is subjected to dynamic pressure ( The jet is cooled and solidified while receiving the pressure to flatten the jet. Therefore, it is necessary to make the circular cross section holding force higher than the dynamic pressure. The circular cross section holding force is inversely proportional to D, where D is the diameter of the circular cross section, and the larger the diameter of the linear solder, the more difficult it is to spin. Therefore, when spinning the Bi-added Sn-Ag solder in a rotating liquid, it is difficult to make the wire diameter 0.2 mm or more, and the wire diameter becomes 1 mm or more.
In order to form a collective wire having substantially the same cross-sectional area as a linear solder of ２2 mm, wire processing having a length of 25 to 100 times is required, and an increase in processing cost is inevitable.

It is an object of the present invention to sufficiently modify a lead-free base solder alloy, for example, a Sn-Ag-based solder by adding Bi, even though the modified composition is brittle. An object of the present invention is to process the wire at a low cost so that it can be used as a linear solder with flux.

[0006]

SUMMARY OF THE INVENTION A method for producing a linear solder according to the present invention is a method for producing a linear prepared solder in which Bi is added to a base solder alloy. The material is processed into a wire by drawing a part of the composition material into a wire by drawing, and the other composition material is processed into a wire by a rotating liquid spinning method in which a molten solder jet is jetted into a rotating cooling liquid layer and spun. This is a configuration characterized by combining lines.

The linear solder according to the present invention is a linear solder produced by the above-described method for producing a linear solder, wherein the base solder alloy is an Sn-Ag alloy, and the divided composition is Sn-Ag. System and Sn-Bi system, Sn-Ag
A line obtained by drawing the Sn-Ag-based composition material is combined with a line obtained by drawing the Sn-Bi-based composition material in the spinning liquid. A configuration in which a line and a flux are formed by spinning the Bi-based composition material in a rotating liquid, or a line by drawing a Sn-Ag-based composition material and a line by spinning the Sn-Bi-based composition material in a rotating liquid. Is formed by twisting or assembling, the flux is impregnated, or the flux is embedded in the wire drawn by the Sn-Ag-based composition material. A flux can also be incorporated in a line formed by drawing an Ag-based composition material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the base solder alloy has a low lead content which is sufficiently effective for lead-free or environmental protection, but has poor wettability which is a basic property of solder, It is intended to improve the wettability by addition. In the following embodiments, an Sn-Ag solder alloy is used as a base solder alloy as an example. Now, the Sn-Ag base solder alloy is changed to B
The prepared composition material modified by the addition of i is assumed to have a composition composed of a weight% of Ag, b weight% of Bi, and the balance Sn, and is expressed as Sn-aAg-bBi. Thus,
The eutectic composition of Sn-Ag is Sn-3.5Ag, the eutectic point is 221 ° C., and it is desirable that Sn-3Ag-bBi be an adjustment composition in view of the soldering temperature of the electronic component. In this adjusted composition, if the added amount of Bi exceeds 3% by weight, embrittlement becomes remarkable, and it becomes difficult to draw a wire having a wire diameter of 1 mmφ required for a linear solder. Despite exceeding 3% by weight, it can be used as a linear solder.

FIGS. 1A and 1B show different examples of the linear solder according to the present invention.
Sn-yA as a composition material that can be easily drawn
g-zBi composition material (Ag is y% by weight, Bi is z% by weight,
The Sn-xBi composition material (Bi is x wt%, the balance being Sn) is considerably brittle and the balance is Sn and the weight ratio of w wt% to (100-w) wt% The Sn-yAg-zBi composition material is linearly processed by drawing, and the Sn-xBi composition material is linearly processed by a rotating liquid prevention method, and a line having a larger cross-sectional area, usually Sn-y
A flux f is incorporated in the line n of the Ag-zBi composition material and a groove is machined.
A line m of the xBi composition material is inserted. These lines are swaged with a die or the like, and are shown in FIGS.
As shown in (1), the line m can be held in the line n. In this case, as shown in (e) and (f) of FIG.
It is preferable to divide the line m into a plurality of lines to increase the degree of dispersion. Also, as shown in FIG. 1 (g), a groove is formed in the line n, the line m and the flux f are accommodated in this groove, and further swaged with a die or the like to form a groove in FIG. 1) hugging the line m to the line n as shown in FIG.
As shown in (i), the line m can be divided into a plurality of lines to increase the degree of dispersion.

[0010] Between the above a, b, x, y, z, w,

A = wy / 100 (1)

## EQU2 ## The relationship of b = wz / 100 + (100-w) x / 100 (2) is established. For the above-mentioned melting point, Sn-
When 3Ag-bBi is used as the preparation composition material, a = 3.
As described above, Bi is added to improve the poor wettability of Sn-3Ag, and the composition of the prepared composition material is changed to Sn-3Ag-5B with the amount of Bi added being 5% by weight.
Assuming that i, in the above equations (1) and (2), a =
3, b = 5,

## EQU00003 ## 3 = wy / 100 (1 ')

The relationship of 5 = wz / 100 + (100−w) x / 100 (2 ′) is established. Among the divided composition materials, S
The nyAg-zBi composition material is a prepared composition material Sn-3Ag
As described above, it is considered that the wire is more excellent in drawability than -5Bi. Particularly, in the Sn-3Ag-zBi composition material, when Bi exceeds 3% by weight, it becomes critically difficult to draw. , Z <3, and z = 0 is desirable. Therefore, the prepared composition material Sn-3Ag-5Bi
A preferred system for separating Sn-yAg and Sn-xBi.

Further, Sn-xBi is eutectic and x = 57
Further, the wire diameter of the Sn-xBi composition material is made as small as possible (0.2 to 0.05 mm), while the wire diameter of the Sn-yAg composition material is made close to about 1 mm. Weight ratio), and thus, it is desirable to determine y with known x and w. In this way, in soldering, first, the eutectic Sn-57Bi has a temperature of 139 ° C.
And the wire of the Sn-yAg composition material is dissolved in the melt, and the dissolution rate is accelerated by a further temperature rise.
When the melting is completed, the soldering is completed. The soldering completion temperature depends on the prepared composition material Sn-3Ag-5Bi.
The temperature is sufficiently close to the soldering temperature.

In FIG. 1, the sectional area and specific gravity of the line m of the Sn-xBi composition material are Sm and ρm, and Sn-y
Assuming that the total cross-sectional area and specific gravity of the Ag-zBi composition material desirably Sn-yAg line n are Sn and pn,

Sm · ρm / (Sn · ρn) = (100−w) / w (3) holds, and the sectional area of one line m of the Sn—xBi composition material is represented by s.
m, the number is m,

Sm = sm · m (4) holds. In the linear solder of the embodiment shown in FIG.
The total cross-sectional area Sm + Sn is set substantially equal to the cross-sectional area of a single line having a diameter of 1 to 1.5 mm.

The spinning in liquid spinning apparatus shown in FIG. 2 can be used for wire drawing of the Sn-xBi composition material in the spinning liquid prevention method. The spinning apparatus shown in FIG. The molten solder jet 10 jetted from the quartz nozzle 33 is incident on the liquid layer 32 at the same speed and in the same direction as the peripheral speed of the cooling liquid layer 32, and the liquid layer incident jet is rapidly cooled and solidified by the cooling liquid layer 32 to spin. I will do it. In this case, the jet in the space from the nozzle to the cooling liquid layer has a circular cross-section because the circular shape of the nozzle is held by the surface tension of the molten metal. Further, the peripheral speed of the cooling liquid layer, the incident angle of the cooling liquid layer of the jet, and the like are set so that the circular holding force due to the surface tension of the jet is larger than the dynamic pressure of the cooling liquid layer (the pressure for flattening the jet). The jet that has been adjusted and incident on the cooling liquid layer also cools and solidifies while maintaining a circular cross section. The diameter of the linear solder that can be spun in this way is usually
It is 0.05 to 0.2 mm.

FIGS. 3A and 3B show another embodiment of the linear solder according to the present invention, which is different from the above.
A wire n obtained by drawing a g-based composition material and a wire m obtained by spinning a Sn-Bi-based composition material in a rotating liquid are twisted or assembled and impregnated with a flux f. In addition, a flux is incorporated in at least a part of the wire formed by drawing the Sn—Ag-based composition material, or a flux is incorporated in at least a part of the wire formed by drawing the Sn—Ag-based material, and the twisted wire is used. Alternatively, the flux can be impregnated into the collecting wire.In the latter case, the activity of the built-in flux can be made higher than that of the external flux in order to reduce the scattering based on the moisture absorption of the flux due to the outside air. preferable.

In FIG. 3, a line m of the Sn—xBi composition material
Is defined as Sm and ρm, and Sn-yAg
Assuming that the total cross-sectional area and specific gravity of the -zBi composition material desirably Sn-yAg line n are Sn and pn,

Sm · ρm / (Sn · ρn) = w / (100−w) (3 ′) holds, and the cross-sectional area of one line m of the Sn-xBi composition material is represented by s.
m, the number is m, the cross-sectional area of one Sn-yAg-zBi composition material desirably Sn-yAg line n is sn, and the number is n
given that,

Sm = sm · m (4 ′)

The following holds: Sn = sn · n (5 ′) In the linear solder of the embodiment shown in FIG.
The total cross-sectional area Sm + Sn is set substantially equal to the cross-sectional area of a single line having a diameter of 1 to 1.5 mm, m is 1 to 4, and n is 2
And the diameter of the wire of the Sn-xBi composition material by the rotation liquid prevention method is 0.05 to 0.2 mm, and Sn-yA
The g-zBi composition material desirably has a wire diameter of 0.5 to 1.2 mm by wire drawing of Sn-yAg.

As the above-mentioned flux, a flux excellent in flexibility is used in order to impart flexibility to the solder with flux to facilitate winding by a bobbin and to prevent flux cracking at the time of bending. Is preferred. Further, it is desirable to use a flux residue after soldering that can be used as an insulating film as it is. Such fluxes include rosin or / and modified rosin, activator and melt flow rate 500 g / 10 m
1 to 50% by weight of ethylene / vinyl acetate copolymer
Preferably, the composition contains 5 to 30% by weight, and if necessary, 5 to 30% by weight, preferably 10 to 25% by weight of fatty acid amide and / or fatty acid bisamide. The above melt flow rate is JIS
Measured based on K7210-1976, inner diameter φ9.5
A sample was filled into the hole of a heater cylinder having a through hole of 0 ± 0.03 mm, and a die having an inner diameter φ2.095 ± 0.005 mm at the lower end of the hole, and a weight was attached to the upper end. Using a test device in which the lower end of the piston is inserted into the above hole, the extrusion weight W (g) for 10 minutes when the weight of the weight is 325 gf {3.185 N} and the test temperature is 125 ° C. And obtained from Wg / 10 minutes. The above-mentioned fatty acid amide / fatty acid bisamide is used for suppressing the adhesion of the flux residue and for preventing the flux from being cut off (occurrence of flux impregnation), for example, stearic acid amide / stearic acid bisamide, palmitic acid amide One or more of these can be used. The rosin or / and modified rosin includes:
Natural rosin, polymerized rosin, phenol-modified rosin, maleated rosin, hydrogenated rosin and the like can be used. Examples of the activator include a hydrohalide of an organic amine, an organic acid, and a salt of an organic acid and an organic amine. For example,
Diethylamine hydrochloride, cyclohexylamine hydrochloride,
Dioctylamine hydrochloride, propylamine hydrochloride, diethylamine hydrobromide, cyclohexylamine hydrobromide, dioctylamine hydrobromide, propylamine hydrobromide, glutaric acid, adipic acid, sebacic acid, Methylmaleic acid, cyclohexylamine adipate and the like can be used. Furthermore, a corrosion inhibitor (for example, phthalic acid,
A benzotriazole compound, a gallic acid ester such as n-propyl gallate, an antioxidant (eg, dibutyl cresol, etc.) may be added, and the amount of addition may be 1-3 to 100 parts by weight of the main component. Parts by weight.

FIG. 4 shows an example of a manufacturing apparatus used for manufacturing the linear solder with flux shown in FIG.
In FIG. 4, reference numeral 41 denotes a supply bobbin on which a stranded wire of the wires m and n manufactured in the previous step is wound. 42 is a flux bath and 43 is a guide roll. Reference numeral 44 denotes a wiper, which can use a die. 45 is a cooler, for example, an air cooler. 46 is a winding hobbin. In order to manufacture the linear solder with flux according to the present invention using this manufacturing apparatus, the flux in the bath 420 is heated to
The stranded wire mn fed from the supply bobbin 41 is immersed in a molten flux 42 to impregnate the molten flux with the molten flux, and excess flux is wiped off with a die wiper 44 to impregnate. After the flux is cooled and solidified by the cooler 45, the flux is wound around the winding bobbin 46. Dice Whipper-44
Instead of wiping the excess flux, the excess flux can be wiped off by blowing hot air.

In the above, a flux dissolved with a low boiling point solvent, for example, xylene or isopropyl alcohol, may be used in the flux bath, and the solvent may be evaporated by blowing the above-mentioned hot air to solidify the flux.

FIG. 5 shows another example of a manufacturing apparatus used for manufacturing the above solder with flux. In FIG.
Reference numerals 41,... Are supply bobbins arranged in parallel. Some of the bobbins have the above-mentioned spinning wire m, and the other bobbins have the above-mentioned drawing wire n.
Has been wound up. 42 is a flux bath, 43,... Are guide rolls in the bath for each wire, and 47 is a dice for assembling in the bath. Reference numeral 44 denotes a wiper, which can use a die, a hot air blower or the like. 45 is a cooler, 46 is a winding hobbin. In order to manufacture the above-mentioned linear solder with flux using this manufacturing apparatus, the flux in the bath 420 is heated to a height.
, And the solder wires m,..., N,... Drawn out from the supply bobbins 41 are held in the molten flux by guide rolls 43,. The excess flux is wiped off with a die wiper 44 outside the flux bath, cooled and solidified by a cooler 44, and then wound up by a winding bobbin 46. Also in this case, the excess flux can be wiped off by blowing hot air instead of wiping the excess flux by the die wiper.
Also, a low boiling solvent such as xylene,
Using a flux dissolved in isopropyl alcohol or the like, the solvent can be evaporated by blowing the above-mentioned hot air to solidify the flux.

In the above example, the lines m, n
The assembling dies are arranged outside the flux bath, and the flux attached wire drawing group is passed through the assembling dies at the stage where the flux exhibits tackiness before solidification, and then assembled. The flux can also be solidified by cooling and solidifying or evaporation of the solvent by heating. Also, the flux-attached wire drawn from the flux bath is cooled or heated to semi-solidify the flux, and then passed through an assembling die to maintain the aggregated state by the adhesive force of the semi-solidified flux, and then re-assembled. It is also possible to finally solidify the flux by cooling or heating.

In the above example, a horizontal flux bath is used, but a vertical flux bath may be used. For example, as shown in FIG.
A plurality of nipples 421,... Are attached to the bottom wall of the molten flux 42 through the nipples 421,. The excess flux of the flux-impregnated assembly wire gathered by the die 47 and exiting the bathtub is wiped off by the die wiper 44, cooled and solidified by the cooler 45, and then wound around the winding bobbin 46. .

In the present invention, Bi is added to a lead-free base solder alloy to prepare a basic composition required for the solder, for example, to improve the wettability.
In order to be usable in the form of a linear solder, the composition is divided into a composition having a different composition, which is easier to draw than the prepared composition, and the remaining composition. Is spun by a spinning method in a rotating liquid, and both lines are combined.In each composition material, other metal elements, for example, copper or copper, within a range that does not substantially affect drawability or spinnability. Silver may be included.

In the above embodiment, the Sn-Ag system is used as the lead-free base solder alloy.
The present invention can be applied to an n-Zn system or a Sn-Sb system.

[0024]

[Embodiment 1] Lead-free base solder alloy S
Provided is a linear solder of prepared composition material Sn-4Bi-3Ag in which Bi is added to n-3Ag to improve wettability. Using the one shown in FIG.
A drum having an inner diameter of 500 mm and a width of 45 mm was rotated at 200 rpm to form a layer of about 1500 ml of isopropyl alcohol. In this cooling liquid layer, a Sn-57Bi composition material melted with a heater was added with nitrogen gas. By pressure, inner diameter 9
jet from a quartz glass nozzle having a diameter of 0.1 mm and a length of 150 mm at the same speed as the peripheral speed of the cooling liquid layer.
A 5 mm Sn-57Bi wire was obtained. In addition, Sn-3.3
Ag was drawn into a line having a diameter of 0.85 mm. Then, four Sn-57Bi wires having a diameter of about 0.15 mm and two 0.85 mm Sn-3.3Ag wires having a diameter of about 0.15 mm are twisted together,
The flux was impregnated to produce a flux-coated linear solder having a solder cross-sectional area substantially equal to a single-wire cross-sectional area having a diameter of 1.2 mm.

[Example 2] In the same manner as in Example 1, a linear solder of Sn-4Bi-3Ag, a prepared composition material obtained by adding Bi to a lead-free base solder alloy Sn-3Ag to improve wettability, was used. provide. A Sn-3.3Ag composition material having a diameter of 1.2 mm and a line having four grooves separated by 90 ° in the circumferential direction was drawn, and a wire having a diameter of 0.15 mm by the rotation liquid prevention method used in Example 1 was used. A flux-containing linear solder was manufactured by accommodating a flux with one Sn-57Bi wire in each groove.

COMPARATIVE EXAMPLE 1 A flux-free solder having an outer diameter of 1.2 mm was manufactured from a lead-free base solder alloy Sn-3.5Ag.

Comparative Example 2 Sn-4Bi-
An attempt was made to draw 3Ag, but drawing with an outer diameter of 2 mm or less was impossible.

Comparative Example 3 Sn-4Bi-
When 3 Ag was spun under the same spinning liquid spinning conditions as in Example 1, the number of aggregates was 144 in order to obtain a linear solder having a wire diameter of 0.1 mm and a cross-sectional area of a single wire having a diameter of 1.2 mm.
It is necessary to use a large number of these, and the cost is significantly higher than that of the embodiment.

In the examples and comparative examples, the flux was composed of 24% by weight of natural rosin, 25% by weight of hydrogenated rosin, 30% by weight of stearamide, and Melt-flow resin.
1000g / 10min ethylene-vinyl acetate copolymer 2
0% by weight, cyclohexylamine hydrobromide 0.5% by weight (activator), dibromopropanol 0.5% by weight
The composition of (activator) was used.

For each of the flux-lined solders of Examples 1 and 2 and the flux-cored solder of Comparative Example 1, the spread rate was determined based on the JIS Z 3197-1986 soldering resin flux test method 6.10 spread test. As a result of measurement (the number of each sample was set to 20), the example product was 88% for both the example products 1 and 2, and the comparative example 1 was 85%, and all the example products were superior to the comparative example product. It exhibited wettability.

In the solders of Examples 1 and 2, the Sn-57Bi composition material was eutectic, melted at 139 ° C., and the Sn-3.5Ag composition material dissolved in the melt.
This melting speed is accelerated by the temperature rise, and the completion of the melting ends the soldering. Thus, the temperature required for this soldering is slightly higher than the soldering temperature of Sn-4Bi-3Ag.

[0032]

According to the present invention, according to the present invention, lead free
Or a solder alloy containing a small amount of lead, particularly Sn-Ag
System, Sn-Zn system, Sn-Sb system
Despite the addition of i, the wettability, which is a basic property of the solder alloy, can be improved by the addition of Bi while ensuring workability and economic efficiency by using the drawing process and the spinning method in a rotating liquid in combination. Correction soldering or post-mounting of the mounted electronic component by soldering can be performed safely without lead pollution.

[Brief description of the drawings]

FIG. 1 is a view showing another embodiment of the linear solder according to the present invention.

FIG. 2 is a view showing a rotary liquid spinning apparatus used for producing a wire m in a linear solder according to the present invention.

FIG. 3 is a drawing showing another embodiment of the linear solder according to the present invention, which is different from the above.

FIG. 4 is a drawing showing an example of a manufacturing apparatus used for manufacturing a linear solder according to the present invention.

FIG. 5 is a drawing showing an example of another manufacturing apparatus used for manufacturing the linear solder according to the present invention.

FIG. 6 is a drawing showing an example of another manufacturing apparatus used for manufacturing the linear solder according to the present invention.

[Explanation of symbols]

 n, m Wire drawing of different solder composition materials f Flux

Claims (6)

[Claims] 1. A method for producing a linear prepared solder in which Bi is added to a base solder alloy. The prepared solder material is divided into composition materials having different compositions, and a part of the composition material is processed into a wire by drawing. A method for producing a linear solder, comprising processing a wire by a spinning method in a rotating liquid in which another composition material is jetted into a rotating cooling liquid layer by injecting a molten solder jet and spinning, and these lines are collectively processed. 2. A linear solder manufactured by the method for manufacturing a linear solder according to claim 1, wherein the base solder alloy is Sn.
-Ag-based alloy, and the divided composition materials are a Sn-Ag-based material and a Sn-Bi-based material. A linear solder, wherein 3. A line formed by drawing a Sn—Ag-based composition material into S
3. The linear solder according to claim 2, wherein a wire and a flux of the n-Bi-based composition material by a spinning method in a rotating liquid are incorporated. 4. A line obtained by drawing a Sn—Ag composition material and S
3. The linear solder according to claim 2, wherein the batch of the n-Bi-based composition material and the wire by spinning in a rotating liquid is performed by twisting or assembling. 5. The linear solder according to claim 4, wherein a flux is incorporated in at least a part of the wire formed by drawing the Sn—Ag-based composition material. 6. The linear solder according to claim 4, wherein the flux is impregnated.