Environmental-protection low halogen-content surface mounting adhesive capable of quick solidification under low temperature

Abstract

The invention discloses an environmental-protection low halogen-content (the total halogen content is smaller than 450ppm) surface mounting adhesive capable of quick solidification under low temperature. The adhesive is composed of high-purity liquid epoxy resin, modified epoxy resin, high-purity active diluent, a halogen-free latent firming agent, an accelerating agent, a thixotropic agent, an ion absorbing agent, high-purity inorganic padding and pigment. The weight percent of the above components is as follows: the high-purity liquid epoxy resin: 20 to 80%; the modified epoxy resin 0 to 10%; the high-purity active diluent: 1 to 10%; the halogen-free latent firming agent: 1 to 8%; the accelerating agent: 2 to 20%; the thixotropic agent 3 to 10%; the ion absorbing agent: 0 to 1%; the high-purity inorganic padding: 0 to 30%; and pigment: 0 to 3%. Compared a the present product, the halogen content of the adhesive is low, the total halogen content is smaller than 450ppm, the thixotropy is good, and the electric performance is excellent. The adhesive can be quickly solidified in 40 to 50 seconds under the temperature of 100 DEG C. With high adhesion power and good heat / impact resisting performance, the adhesive can be widely used in the technical field of surface mounting with strict requirement for environmental protection.

Description

technical field [0001] The invention relates to a surface-mounting adhesive, in particular to a low-halogen surface-mounting adhesive which can be cured quickly at low temperature and is mainly used for wave soldering and reflow soldering, and is suitable for current environmental protection requirements. Background technique [0002] On a global scale, the pace of development of electronic technology and its various applications has never stopped. More and more functions are being integrated into smaller modules. Due to the pursuit of miniaturization of electronic products, the perforated plug-in components used in the past can no longer be reduced, and the functions of electronic products are more complete. The integrated circuits (IC) used have no perforated components, especially large-scale and highly integrated ICs have to use SMD components , product batching, production automation, the factory should produce high-quality products at low cost and high output to meet ...

AI Technical Summary

Problems solved by technology

[0010] The characteristics of epoxy surface mount adhesives: good dispensing performance, consistent glue dot profile and size, high wet strength and curing strength, fast curing speed, storage stability, flexibility and temperature shock resistance, etc. However, as a surface mount adhesive, the two characteristics of fast curing and storage stability are contradictory. If the curing speed is increased, the storage period will definitely be shortened, and the viscosity will increase, which will affect the operability. However, if the storage stability is improved , then the curing speed will slow down, affecting the bonding strength, resulting in components falling off easily during wave soldering

Traditional adhesives cannot achieve fast curing, high bonding strength and stable storage period. Ordinary epoxy resins are synthesized with bisphenol A and epichlorohydrin, and there are a large number of free chloride ions in the synthesis process. Invisibly, this content cannot meet the current environmental protection requirements. The traditional epoxy resin adhesive content is above 2000ppm, and in order to meet the current environmental protection requirements, many components cannot withstand heat, so the curing temperature of the adhesive is required to be low. It cannot exceed 120 degrees. The curing temperature of traditional patch adhesives is generally 150 degrees. For this reason, we have invented a surface mount epoxy resin with low halogen content that can be cured quickly at low temperature, has high bonding strength and stable storage period. Adhesive