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Welding flux and brazing filler metal composition for brass solder

A brazing and composition technology, applied in welding/cutting media/materials, welding media, welding equipment, etc., can solve the problems of deterioration of flux fluidity, deterioration of solder wettability, inability to maintain activity, etc. Excellent insulation and enhanced joint effect

Inactive Publication Date: 2002-10-16
FUJI ELECTRIC CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, when such a conventional epoxy-based solder is used with lead-free solder (a flux that does not contain lead in the solder) that has a higher melting point than lead-based solder, for example, Sn- When used in Ag-based flux, a large amount of activator carboxylic acid is consumed in the hardening reaction with epoxy resin before the flux is melted, so its activity cannot be maintained, and the fluidity of the flux deteriorates, causing solder wetting. Phenomenon of deterioration such as humidity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Add 4.42 g of cis-4-cyclohexene-1,2-dicarboxylic acid to 4.33 g of triethylene glycol, and heat to about 130° C. to dissolve. After being cooled to below 100 DEG C subsequently, add 10g of cheaper epoxy resin AER 260 (bisphenol A type epoxy resin, epoxy equivalent 192g / eq; Asahi Kasei EPOXY (strain)), stir until uniform, make the present invention of flux. The combination of epoxy resin and carboxylic acid contained in this flux is such that there is 1 equivalent of carboxyl group to 1 equivalent of epoxy group, and the total content of epoxy resin and carboxylic acid is about 77% by mass relative to the total amount of the flux. Alcohol content is about 23% by mass relative to the total amount of flux. After cooling the above flux to room temperature, use Sn-2.5Ag-0.5Cu alloy (Sn 97% by mass, Ag 2.5% by mass, Cu 0.5% by mass, melting point 221°C) , or Sn-3.5Ag-0.5Cu-0.1Ni-0.05Ge alloy (Sn 95.85% by mass, Ag 3.5% by mass, Cu 0.5% by mass, Ni 0.1% by mass and Ge 0.05% b...

Embodiment 2

[0050] Using relatively cheap 2,2-dimethylglutaric acid instead of cis-4-cyclohexene-1,2-dicarboxylic acid in the above-mentioned Example 1, the same brazing as in Example 1 was performed. The starting temperature of the flux reaction is 173°C, and the peak temperature of the exothermic peak is as high as 220°C, so the activity of the carboxylic acid can be maintained, and the hardening reaction proceeds slowly. As in the above-mentioned examples, the wettability of the solder was good, and the storage stability was also good. At 85°C 85%RH, the insulation of the flux hardened product is 6.0×10 7 Ω or so, after 168 hours, the insulation resistance does not decrease. Even if the flux residue is not cleaned, it does not hinder the hardening of the silicone gel sealing resin, and good soldering can be obtained without cleaning the lead-free solder. The compounding ratio and characteristics of the flux of the present invention used in this example are shown in Table 1.

Embodiment 3

[0052] Using relatively cheap L-glutamic acid instead of cis-4-cyclohexene-1,2-dicarboxylic acid in the above-mentioned Example 1, the same brazing as in Example 1 was performed. However, L-glutamic acid is insoluble in triethylene glycol, so it is ground into a fine powder with a mortar before adding, and it becomes dispersed when mixed. The starting temperature of the flux reaction is 214°C, so the activity of the carboxylic acid can be maintained, and the hardening reaction proceeds. As in the above-mentioned examples, the wettability of the solder was excellent, and the storage stability was also excellent. At 85°C 85%RH, the insulation of the flux hardened product is 2.0×10 7 Ω or so. The insulation resistance did not decrease even after 168 hours. Even if the flux residue is not cleaned, it will not cause the hardening of the silicone gel sealing resin to be hindered, and for lead-free solder, good soldering can still be obtained without cleaning. Table 3 shows the c...

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Abstract

The brazing flux of the present invention contains epoxy resin and organic carboxylic acid, and is characterized in that, for the combination of epoxy resin and organic carboxylic acid, for 1.0 equivalent of epoxy group, 0.8-2.0 equivalent of carboxyl group is combined, relative to the total amount of flux, The total content of the epoxy resin and the organic carboxylic acid is 70% by mass or more. The lead-free solder composition of the present invention contains lead-free solder and solder flux. When using the soldering flux of the present invention or the lead-free solder composition of the present invention, soldering is performed with a lead-free solder having a melting point higher than that of lead-based solder (for example, a melting point of 190 to 240° C.), the activity of the flux is maintained, and the solder The wettability is very good, and it does not hinder the hardening of the sealing resin even if the flux residue is not cleaned.

Description

technical field [0001] The present invention relates to a flux for brazing and a solder composition containing it. Background technique [0002] In the past, most soldering fluxes were made by adding activators made of organic acids and halide salts to rosin and rosin-modified resins. However, these residues remain on the printed wiring board after the soldering operation is completed, and these residues cause corrosion, migration, and the like of the base material in many cases. When the printed wiring board with residual residue is sealed with resin (silicone gel, epoxy resin, etc.), the residue will hinder the hardening of the sealing resin and greatly affect the bondability and insulation with the substrate. Therefore, in order to remove the residue, it is cleaned with freon or an organic solvent after the brazing operation. However, since freon, VOC, and the like cause environmental problems, the cleaning agent is currently regulated. [0003] There is an epoxy-based...

Claims

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Application Information

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IPC IPC(8): B23K35/363B23K35/36
CPCB23K35/3613B23K35/3618
Inventor 仁科努冈本健次
Owner FUJI ELECTRIC CO LTD
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