Lead-free soldering paste

A lead-free solder paste and solder paste technology, used in welding media, welding equipment, welding/cutting media/materials, etc., can solve problems such as poor carrier rheology, mismatch between activation point and welding temperature, and large residual after welding. , to improve the flux performance, reduce post-weld residues, and reduce post-weld corrosion.

Active Publication Date: 2011-04-06
ZHEJIANG ASIA GENERAL SOLDERING & BRAZING MATERIAL
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Problems solved by technology

[0005] The present invention aims to solve the common problems of current solder paste, that is, poor rheology of the carrier, mismatch between activation point and soldering temperature, large residue after soldering, etc., and provides a lead-free solder paste of the present invention for this purpose. Solder paste has good welding performance, printing performance and spreadability, and less residue after soldering

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Embodiment Construction

[0021] The examples are described to further explain the invention. These examples are generally illustrative rather than restrictive. In the examples, the percentages represent weight percentages unless otherwise specified.

[0022] The following are Examples 1-5 and Comparative Examples 1-5 of the solder paste formulation of the present invention, see Table 1:

[0023] Table 1 Flux Formula Table

[0024]

[0025] In the present invention, an activator made of an organic acid containing two carboxyl groups, a halogen-containing compound salt and an alkanolamine salt is added to the flux of the solder paste, the activator can continuously react with the tin powder, and the reaction temperature ranges It is very broad and also shows a strong effect of removing oxide film.

[0026] After the products obtained from the above-mentioned comparative examples and examples, referring to the detection method of SJ / T11186-199 "General Specification for Tin-Lead Paste Solder", the ...

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Abstract

The invention discloses a lead-free soldering paste with favorable welding performance, printing performance and spreadability and fewer welded residues. The lead-free soldering paste is formed by mixing 8-20 percent by weight of soldering flux and 80-92 percent by weight of SnAgCu series solder powder. The soldering flux comprises the components: 38-44 percent by weight of colophony, 6.5-7.0 percent by weight of activating agent, 41-45 percent by weight of organic solvent and 2.4-7.0 percent by weight of thixotropic agent, wherein the activating agent comprises halogen composite salt, dicarboxylic acid and alcohol amine salt; the organic solvent is formed by matching solvent with high boiling point being more than 220DEG C and solvent with low boiling point being less than 220DEG C; the thixotropic agent comprises one or two of daiamid, hydrogenated castor oil, fatty glyceride and N, N-ethylene distearate; and the SnAgCu series solder powder is formed by mixing 96.5-99.0 percent by weight of Sn powder, 0.3-3.0 percent by weight of Ag powder and 0.5-0.7 percent by weight of Cu powder. The invention is applicable to the surface mounted process in the electronic industry.

Description

technical field [0001] The invention relates to a soldering solder paste for electronic components, in particular to a lead-free soldering paste with high soldering performance based on Sn-Ag-Cu alloy. Background technique [0002] With the development of electronic products towards ultra-large-scale integration, digitization and miniaturization, surface mount technology (SMT) has become the mainstream technology of electronic assembly. Traditional tin-lead solder paste can basically meet these requirements, but because it contains a lot of lead, long-term use will bring great harm to human living environment and safety. Therefore, the United States and the European Union have promulgated legislation prohibiting the use of lead and its compounds, and many countries, including my country, have formulated national standards for lead-free solder. Compared with tin-lead solder paste, the melting point of lead-free SnAgCu series solder paste is about 34°C higher, which brings se...

Claims

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Application Information

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IPC IPC(8): B23K35/362B23K35/26
Inventor 金霞郭建军杨倡进王大勇刘保祥潘洪亮
Owner ZHEJIANG ASIA GENERAL SOLDERING & BRAZING MATERIAL
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