JP2010046688A - Flux for soldering and soldering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To select an exact organic halide according to solder in consideration of the fact that, when organic the halide is used as flux for soldering, the activation temperature of the organic halide is influenced by the kind of the metal of solder which is made coexistent with the organic halide. <P>SOLUTION: The flux to an Sn-containing lead-free multi-metal alloy comprises: at least one kind of organic halide (a) in which an exothermic peak in differential calorimetry in the coexistence with the multi-metal alloy solder lies in the range of less than the melting point of the multi-metal alloy and also ≥90°C; and at least one kind of organic halide (b) in which the exothermic peak lies in the range of ≤330°C and the melting point peak of the multi-metal alloy or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a soldering flux and a soldering method.

The soldering flux removes the oxide film on the surface of the base material, covers the base material and the molten solder and shields it from the air to prevent oxidation, enhances the wettability of the solder and promotes workability (soldering workability) In addition, it plays the role of improving solder adhesion on the surface of the base material.
Flux residue is generated after soldering, and in the past, flux residue was cleaned and removed, but nowadays it has become common to leave flux residue from the point of eliminating the use of solvents based on environmental conservation. . As a result, requirements such as water insolubility of the flux residue, copper plate corrosion resistance, and insulation resistance have been required.
The main component of the flux is rosin. Therefore, rosin alone cannot satisfy requirements such as soldering workability, appearance such as voids, cracks, cracks, etc., water resistance of flux residue, corrosion resistance of flux residue, insulation resistance of flux residue, etc. .
Therefore, in soldering fluxes, it is a common practice to add an activator and other additives to rosin.

Many activators have been proposed, one of which is an organic halide. (Patent Document 1, Patent Document 2, etc.)
Japanese Patent Laid-Open No. 08-155676 JP, 2001-138089, A In organic halide, although it dissociates and shows activity at predetermined temperature, according to the present inventors' earnest examination result, in the case of lead-free solder, halogen in the presence of solder is present. It was confirmed that there was a difference between the dissociation temperature (activation temperature) and the halogen dissociation temperature (activation temperature) under the organic halide alone. This is presumed to be caused by a specific metal of the solder acting as a catalyst for the halogen dissociation of the organic halide or reacting with the metal surface. Therefore, it is recognized that the activation temperature of the organic halide varies depending on the type of solder metal.

(A) in FIG. 8 shows 2,2,2-tribromoethanol, which is one of organic halides, and Sn—Ag—Cu solder powder (Sn-3.0
g-0.5 u) shows the differential thermal measurement curve of the mixed sample, and 2,2,2-tribromoethanol melts between the temperature y '(endotherm based on the state change), and between the temperature ro' The 2,2,2-tribromoethanol decomposes exothermically and heat is absorbed between the temperature and the heat.
FIG. 8B shows a differential thermal measurement curve of a mixed sample of 2,2,2-tribromoethanol and Sn—Bi (Sn-58Bi) solder powder. 2,2-Tribromoethanol is melted, the solder is melted between the temperature rolls, and 2,2,2-tribromoethanol is exothermicly decomposed between the temperature rolls. Accordingly, when an organic halide is used as an activator for a soldering flux, the activation temperature of the flux differs depending on the solder metal. For example, an organic halide useful as an activator for lead solder is Sn- Whether or not it is effective as an activator for flux of Ag-Cu solder, with respect to the solder of a specific alloy, an organic halide a that exhibits an active action on the lower temperature side than the solder melting point and an organic halide that exhibits an active action on the higher temperature side There arises a problem that the technical significance of adding b to the flux cannot be guaranteed if the solder alloy system is changed.

The purpose of the present invention is to consider that in using an organic halide as a soldering flux, the activation temperature of the organic halide depends on the type of solder metal coexisting with the organic halide. Select the appropriate organic halide according to the solder, such as soldering workability, appearance such as void, tsura, crack, etc., water resistance of flux residue, corrosion resistance of flux residue, insulation resistance of flux residue, etc. A soldering flux that can satisfactorily satisfy both requirements is to provide a soldering method.

The flux for soldering according to claim 1 is a flux for Sn-based lead-free solder, and the exothermic peak in the differential heat measurement in the presence of the solder is less than the melting point peak of the solder and is in the range of 90 ° C. or more. It contains at least one organic halide a, and at least one organic halide b having the same exothermic peak of 320 ° C. or less and in the range of the melting point peak of the multi-component alloy solder.
The soldering flux according to claim 2 is the soldering flux according to claim 1, wherein the melting point of the Sn-based lead-free solder is 170 ° C. or higher and 240 ° C. or lower, and the organic halides a and b are 2,2,2 -Tribromoethanol, 2,3-dibromo-2-butene-1,4-diol, tris (2,3-dibromopropyl) isocyanurate, 2,2-bis [3,5-dibromo-4- (2, 3-Dibromopropoxy) phenyl] propane.
The soldering flux according to claim 3 is the soldering flux according to claim 1 or 2, wherein the Sn-based lead-free solder is Sn, Ag, Cu, Bi, In, Zn, Sb, Ni, Ga, Ge, It is characterized by being one or more selected from the group consisting of Co, Al, Si and P.
The soldering method according to claim 4 is a method of fluxing Sn-based lead-free solder with an organic halide a exhibiting an active action at a temperature lower than a melting point peak of the solder and an organic halide b exhibiting an active action at a high temperature. The organic halide b is an organic halide having an exothermic peak in the differential heat measurement in the presence of the solder alloy on the low temperature side, and soldering the organic halide b. Further, an organic halide having an exothermic peak in differential heat measurement in the presence of the solder alloy on the high temperature side is used.
The solder containing spear according to claim 5 is characterized in that the flux is the soldering flux according to any one of claims 1 to 3.
The solder paste according to claim 6 is characterized in that the flux is the soldering flux according to any one of claims 1 to 3.

In an organic halide used as an activator for soldering flux, the temperature at which the solder metal acts as a catalyst for halogen dissociation of the organic halide or reacts with the metal surface to cause halogen dissociation is the same as that of the organic halide. It depends on the type of solder metal that coexists.
Therefore, in the present invention, the differential thermal curve of the coexisting sample of the solder to be used and the organic halide is measured, the organic halide a that generates an exothermic peak at a lower temperature side than the melting point peak of the solder, and the melting point peak of the solder Since the organic halide b that generates an exothermic peak on the higher temperature side is added to the flux as an activator, it corresponds to the type of solder metal in both the low temperature side and the high temperature side of the solder melting point. The active action can be performed accurately.
Accordingly, it is possible to satisfactorily achieve removal of the oxide film on the surface of the base material before melting the solder, prevention of oxidation of the molten solder after melting the solder, and promotion of soldering work due to excellent wettability of the solder.

FIG. 1 (a) shows a general differential thermal measurement curve in the coexistence of the organic halide a used in the present invention and the solder used, and the organic halide a is solid between the temperatures II ′. From the melting point to the liquid, exhibiting a melting point peak due to endotherm, and the organic halide a dissociates the halogen between the temperature rolls and exhibits an exothermic peak due to the reaction with the activated metal surface. The solder melts from a solid to a liquid and exhibits a descending melting point peak due to endotherm.
FIG. 1 (b) shows a general differential thermal measurement curve in the presence of the organic halide b used in the present invention and the solder used, and the organic halide b is solid between the temperature y '. From melting to liquid, exhibiting a melting point peak due to endotherm, and the solder transforms from the solid phase to the liquid phase and melts between the temperature and the melting point due to endotherm. The organic halide b dissociates the halogen between the temperature rolls and exhibits an exothermic peak due to the reaction with the activated metal surface. The organic halide a aims at removing the oxide film on the surface of the base material before melting of the solder, and the organic halide b aims at promoting the wetting of the molten solder.

In the present invention, the reason why the lower limit on the low temperature side is 90 ° C. is that, even if the activator is operated while the flux is in a solid state, penetration of the flux due to capillary action of the flux, spreading of the flux, etc. do not occur. This is because the effective use of is not realized.
The reason why the upper limit on the high temperature side is set to 320 ° C. is that when an organic halide b having an exothermic peak exceeding 320 ° C. is used, the activation of the organic halide remains incomplete and does not follow the effective use of the activator. is there.

Organic halides include 2,2,2-tribromoethanol, tribromomethylphenylsulfone, 2,3-dibromo-2-butene-1,4-diol, pentaerythritol tribromide, isocyanuric acid tris (2,3 -Dibromopropyl)
2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane and the like.
Each addition amount of the organic halide a and the organic halide b with respect to the flux is set to 0.2 to 4.0%. If it is less than 0.2%, the activation action is insufficient, and if it exceeds 4.0%, it is difficult to guarantee the copper plate corrosiveness of the flux residue. Preferably, the content is 0.5% to 30%.
It is also possible to use organic halides whose halogen is chlorine, fluorine or iodine.

The solder in which the flux of the present invention is used is a Sn-based lead-free solder having a melting point of 170 ° C. to 240 ° C., and is at least one alloy selected from Sn, Ag, Cu, Bi, In, and Zn.
For example, Sn-3.0Ag-0.5Cu (Ag: 3.0% by mass, Cu: 0.5% by mass, balance Sn. Solidus temperature 217 ° C., liquidus temperature 219 ° C.), Sn-0. 3Ag-0.7Cu (solidus temperature 217 ° C, liquidus temperature 227 ° C),
Sn-1.0Ag-0.7Cu (solidus temperature 217 ° C, liquidus temperature 227 ° C), Sn-0.7Cu (solidus temperature 227 ° C, liquidus temperature 228 ° C), Sn-3. 0Cu (solidus temperature 227 ° C, liquidus temperature 312 ° C), Sn-3.5Ag (solidus temperature 221 ° C, liquidus temperature 221 ° C), Sn-3.5Ag-0.5Bi-8In ( Solidus temperature 196 ° C, liquidus temperature 206 ° C), Sn-2.5Ag-1.0Bi-0.5Cu (solidus temperature 214 ° C, liquidus temperature 217 ° C), Sn-8Zn-3Bi ( Solid phase temperature 187 ° C., liquidus temperature 196 ° C.) and Sn (solidus temperature 234 ° C., liquidus temperature 234 ° C.).
One or more metals selected from the group consisting of Sn, Ag, Cu, Bi, In, Zn, Sb, Ni, Ga, Ge, Co, Al, Si, and P are added to these solders. You can also.

As the organic halide a for the Sn—Ag—Cu solder or Sn—Cu solder, 2,2,2-tribromoethanol (melting point: 82 ° C., having an exothermic peak between 120 ° C. and 140 ° C.), 2 , 3-Dibromo-2-butene-1,4-diol (melting point: 110
° C. Exothermic peak between 140 ° C. and 180 ° C.), pentaerythritol tribromide (melting point: 69 ° C., exothermic peak between 180 ° C. and 210 ° C.) can be used, and organic halide b is isocyanuric acid Tris (2,3-dibromopropyl) (melting point: 120 ° C., exothermic peak between 270 ° C. and 300 ° C.), 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) ) Phenyl] propane (melting point: 110 ° C., with an exothermic peak between 300 ° C. and 320 ° C.).

In the flux according to the present invention, one or more of rosin or a derivative thereof is a main component, and in addition to the organic halide as an activator, an amine organic acid salt, an amine halogen salt, a halide, and other oxidations. Additives such as inhibitors can be added.

Examples of the rosin used include wood rosin, gum rosin, tall rosin, disproportionated rosin, hydrogenated rosin, fully hydrogenated rosin, maleic acid-modified rosin, and rosin ester.

Examples of amines include primary amines such as ethylamine, cyclohexylamine and benzylamine, secondary amines such as diethylamine, diethanolamine and diphenylamine, and tertiary amines such as triethylamine, triethanolamine and triisopropanolamine. Or as its organic acid salt or hydrohalide salt. Other amines include quaternary amines such as tetraethylammonium salt, diphenylguanidine and diphenylurea. Examples of the organic acid include diglycolic acid, adipic acid, glutaric acid, dodecanedioic acid, propionic acid, succinic acid, maleic acid and the like.
In addition, polyethylene wax, ester wax, etc. can be added to these compositions, and thermoplastic resins and other polymers should be added within a range that does not significantly affect solderability in order to improve performance against the thermal cycle. Can do.

When the present invention is applied to a solder paste, a high melting point wax such as hardened castor oil or polyamide wax may be added to a high boiling point solvent such as ethylene glycol, glycerin, hexylene glycol or an ester thereof in the above composition. it can.

When the present invention is applied to a liquid flux, the flux having the above composition can be dissolved in an appropriate concentration in a solvent such as isopropyl alcohol, xylene, or butyl acetate.

[Example 1]
The embodiment is a solder containing solder, and Sn-3.0Ag-0.5Cu was used as the solder.
Use 2,2,2-tribromoethanol as the organic halide a. As the organic halide b, tris (2,3-dibromopropyl) isocyanurate was used.
Mixed sample of 2,2,2-tribromoethanol and Sn-3.0Ag-0.5Cu powder (melting start temperature 217 ° C, solidification start temperature 219 ° C) (mass% of 2,2,2-tribromoethanol is 50%) ) Differential heat measurement curve (differential heat measurement device Thermo plus TG8120 manufactured by Rigaku Corporation. Measurement sample weight 20 mg, heating rate 10 ° C./min. The same applies hereinafter) is as shown in FIG. , 2,2-tribromoethanol melting peak, m, 2,2,2-tribromoethanol exothermic peak, and s solder melting peak.
The differential thermal measurement curve of the mixed sample of tris (2,3-dibromopropyl) isocyanurate and Sn-3.0Ag-0.5Cu powder (mass% of tris (2,3-dibromopropyl) isocyanurate is 50) is shown in FIG. N represents the melting peak of tris (2,3-dibromopropyl) isocyanurate, s represents the melting peak of solder, and m represents the exothermic peak of tris (2,3-dibromopropyl) isocyanurate. .
A flux was prepared by melting and mixing WW rosin 76%, hydrogenated rosin 20%, 2,2,2-tribromoethanol 2%, and isocyanuric acid tris (2,3-dibromopropyl) 2%. Further, this flux was softened by heating and placed in a Sn-3.0Ag-0.5Cu solder hollow tube, and drawn to an outer diameter of 1.0 mmφ to produce a solder containing a paste.

This spear-containing solder was evaluated by the following test.
Solderability test: Using a soldering robot set at 350 ° C, solder 100 points to a single-sided universal board, ○ for those with no defects, △ for less than 10%, and for those with 10% or more defects. It was evaluated.
Void number test: A case where no void was found in any of the 100-point soldering points in the solderability test was evaluated as ○, a case where the number of voids was less than 5% was evaluated as Δ, and a case where the number of voids was 5% or more was evaluated as ×.
Aqueous solution resistance test: The aqueous solution resistance of the flux residue was measured by the method described in JIS Z 3197, and a high one was evaluated as ◯, a middle one as Δ, and a low one as ×.
Copper plate corrosion test: JIS
Z 3197 was evaluated according to the copper plate corrosion. The case where there was no corrosion was evaluated as ◯, the case where there was no corrosion but a part of the flux was initially greened was evaluated as △, and the case where there was corrosion was evaluated as ×.
Insulation resistance test: Conducted at 85 ° C. RH85% -RH90% in accordance with JIS Z 3197. High resistance samples were evaluated as ◯, medium resistance samples were evaluated as Δ, and low resistance samples were evaluated as ×.
The evaluation results of Example 1 are as shown in Table 2.

[Example 2]
As shown in Table 1, in Example 1, tris (2,3-dibromopropyl) isocyanurate was used as the organic halide b on the high temperature side, whereas in Example 2, the organic halogen on the high temperature side was used. The same as Example 1 except that 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane was used as the compound b.
Mixed sample of 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane and Sn-3.0Ag-0.5Cu powder (2,2-bis [3,5-dibromo The differential calorimetric curve of -4- (2,3-dibromopropoxy) phenyl] propane is 50% by mass is as shown in FIG. 5, where n is 2,2-bis [3,5-dibromo-4- ( 2,3-dibromopropoxy) phenyl] propane melting peak, solder melting peak, m of 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane Each exothermic peak is shown.
The evaluation results of Example 2 are as shown in Table 2.

Example 3
As shown in Table 1, in Example 1, 2% of 2,2,2-tribromoethanol was used as the organic halide a on the low temperature side, whereas in Example 3, 2,2,2- Tribromoethanol 1% and 2,3-dibromo-2-butene-1,4-diol 1% were used. In Example 1, tris (2,3-dibromopropyl isocyanurate was used as the organic halide b on the high temperature side. In the same manner as in Example 2, 2,3-bis [3,5-dibromo-4- (2,3-dibromo) was used as the organic halide b on the high temperature side. Same as Example 1 except that propoxy) phenyl] propane was used.
Mixed sample of 2,3-dibromo-2-butene-1,4-diol and Sn-3.0Ag-0.5Cu powder (mass% of 2,3-dibromo-2-butene-1,4-diol is 50) The differential calorimetry curve is as shown in FIG. 3, where n is the melting peak of 2,3-dibromo-2-butene-1,4-diol and m is 2,3-dibromo-2-butene-1,4. -Exothermic peak of diol and melting peak of s solder are shown.
The evaluation results of Example 3 are as shown in Table 2.

Example 4
In Example 1, 2% of 2,2,2-tribromoethanol was used as the organic halide a, whereas in Example 4, the amount was reduced to 1% of 2,2,2-tribromoethanol. In Example 1, 2% of tris (2,3-dibromopropyl) isocyanurate was used as the organic halide b, whereas in Example 4, tris (2,3-dibromopropyl) isocyanurate was used as the organic halide b. 2) and 1% of 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane. .
The evaluation results of Example 4 are as shown in Table 2.

  Examples 1-4 passed any of a solderability test, a void number test, an aqueous solution resistance test, a copper plate corrosion test, and an insulation resistance test.

[Comparative Example 1]
As shown in Table 1, the same procedure as in Example 1 was used except that 2,3-dibromopropanol liquid at room temperature, which is an organic halide having an exothermic peak not reaching 90 ° C., was used as an activator.
The differential calorimetry curve of a mixed sample of 2,3-dibromopropanol and Sn-3.0Ag-0.5Cu powder (mass% of 2,3-dibromopropanol is 50) is as shown in FIG. 6, where m is 2,3 -Exothermic peak of dibromopropanol and melting peak of s solder are shown.

[Comparative Example 2]
As shown in Table 1, it was the same as Example 1 except that only 2,2,2-tribromoethanol, which is an organic halide a exhibiting activity on the lower temperature side than the melting point of the solder, was used as the activator.

[Comparative Example 3]
As shown in Table 1, the same procedure as in Example 1 was conducted except that decabromodiphenyl ether, which is an organic halide having an exothermic peak exceeding 330 ° C., was used as an activator.
The differential thermal measurement curve of the mixed sample of decabromodiphenyl ether and Sn-3.0Ag-0.5Cu powder (mass% of decabromodiphenyl ether is 50) is as shown in FIG. 7, where n is the melting peak of decabromodiphenyl ether, s The melting peak of solder and m represents the exothermic peak of decabromodiphenyl ether.

[Comparative Example 4]
As shown in Table 1, 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl, which is an organic halide b that exhibits activity on the higher temperature side than the melting point of the solder, as an activator. The same as Example 1 except that propane was used.

[Comparative Example 5]
As shown in Table 1, 2,3-dibromopropanol, which is an organic halide a exhibiting activity on the lower temperature side than the melting point of the solder, and an organic halide b exhibiting activity on the higher temperature side than the melting point of the solder are used as the activator. Same as Example 1 except that some decabromodiphenyl ether was used.

[Comparative Example 6]
As shown in Table 1, as activators, 2,2,2-tribromoethanol and 2,3-dibromo-2-butene-1,4, which are organic halides a that exhibit activity at a temperature lower than the melting point of the solder. -Same as Example 1 except that the diol was used.

[Comparative Example 7]
As shown in Table 1, tris (2,3-dibromopropyl) isocyanurate and 2,2-bis [3,5-dibromo, which are organic halides b that are active on the higher temperature side than the melting point of the solder, as activators. Same as Example 1 except that -4- (2,3-dibromopropoxy) phenyl] propane was used.

[Comparative Example 8]
As shown in Table 1, the same procedure as in Example 1 was performed except that triethylamine hydrobromide, which is widely used as an activator, was used.

The evaluation results of Comparative Examples 1 to 8 are shown in Table 2 together with the evaluation results of Examples 1 to 4.
As is clear from Table 2, in the comparative example, some characteristics are good, but it can be confirmed that any of the other tests have an adverse effect. On the other hand, according to the present invention, good results are obtained in any of the solderability test, void number test, aqueous solution resistance test, copper plate corrosion test, and insulation resistance test.

It is a differential thermal curve which shows the characteristic of the organic halides a and b used as activator use in this invention. It is a figure which shows the differential thermal measurement curve of the mixture of Sn-Cu-Ag solder and 2,2,2-tribromoethanol. It is a figure which shows the differential calorimetry curve of the mixture of Sn-Cu-Ag solder and 2,3-dibromo-2-butene-1,4-diol. It is a figure which shows the differential thermal measurement curve of the mixture of Sn-Cu-Ag solder and isocyanuric acid tris (2,3- dibromopropyl). It is a figure which shows the differential thermal measurement curve of the mixture of Sn-Cu-Ag solder and 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane. It is a figure which shows the differential thermal measurement curve of the mixture of Sn-Cu-Ag solder and 2, 3- dibromo propanol. It is a figure which shows the differential thermal measurement curve of the mixture of Sn-Cu-Ag solder and decabromodiphenyl ether. When using an organic halide as a flux activator, it is a differential calorimetry curve showing that the activation temperature differs depending on the type of solder metal.

Explanation of symbols

m Melting peak of organic halide n Exothermic peak of organic halide s Melting peak of solder

Claims (6)

It is a flux for Sn-based lead-free solder and has the same heat generation as that of at least one organic halide a in which the exothermic peak in the differential heat measurement in the presence of the solder is less than the melting point peak of the solder and in the range of 90 ° C. or higher. A soldering flux comprising at least one organic halide b having a peak of 320 ° C. or lower and a melting point peak or more of the multi-component alloy solder. Sn-based lead-free solder has a melting point of 170 ° C. or higher and 240 ° C. or lower, and organic halides a and b are 2,2,2-tribromoethanol, 2,3-dibromo-2-butene-1,4-diol, 2. Isocyanuric acid tris (2,3-dibromopropyl), 2,2-bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] propane Flux for soldering as described. Sn-based lead-free solder is a solder composed of one or more selected from the group consisting of Sn, Ag, Cu, Bi, In, Zn, Sb, Ni, Ga, Ge, Co, Al, Si, and P. The soldering flux according to claim 1 or 2, wherein the soldering flux is provided. For Sn-based lead-free solder, soldering is performed by adding to the flux an organic halide a that exhibits an active action on the lower temperature side than the melting point peak of the solder and an organic halide b that exhibits an active action on the higher temperature side. There is used an organic halide having an exothermic peak in the differential heat measurement in the presence of the solder alloy in the organic halide a, and the differential heat in the presence of the solder alloy in the organic halide b. A soldering method characterized by using an organic halide having an exothermic peak in measurement on the high temperature side. A solder containing solder, wherein the flux is the soldering flux according to any one of claims 1 to 3. A solder paste, wherein the flux is the soldering flux according to any one of claims 1 to 3.

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