Environment-friendly tin paste special for lead-free low-temperature through hole

Abstract

The invention relates to environment-friendly tin paste special for a lead-free low-temperature through hole. The environment-friendly tin paste is composed of Sn42Bi58 alloy tin powder and flux paste. The flux paste includes, by mass, 1%-6% of a thixotropic agent 6650, 35%-58% of resin KE-604, 2%-3% of a phenolic antioxidant, 1%-2% of a nonionic halogen compound, 35%-55% of ethylene glycol monohexyl ether and 1.5%-7% of an active agent. The weight ratio of the Sn42Bi58 alloy tin powder to the flux paste is 89:11. According to the environment-friendly tin paste, the phenomenon that the tin paste falls off during element inserting in the THT process is effectively solved, and the stability of the paste is kept; few postwelding residues are generated, transparency performance and insulation performance are good, cleaning is avoided, and extremely high postwelding reliability is achieved; and the unit size of the postwelding tin paste is quite stable, and the phenomenon of much tin or little tin cannot happen.

Description

technical field [0001] The invention relates to a welding material for assembling an electronic printed circuit board, in particular to a special environment-friendly solder paste for lead-free low-temperature through-holes. Background technique [0002] With the rapid development of the electronic manufacturing industry, the production of power chargers is becoming more and more modernized. However, due to the limitation of single-sided and double-sided mixed packaging of the product itself, the assembly of power chargers must be made of surface mount (SMT) and through-hole plug-in. (THT) consists of two different processes. Due to the continuous development of electronic processing in the direction of miniaturization and high integration, the electronic components used in power chargers are also getting smaller and smaller, and the assembly density of electronic components is getting higher and higher, especially in In the THT process, the solder paste is easy to drop when...

AI Technical Summary

Problems solved by technology

[0002] With the rapid development of the electronic manufacturing industry, the production of power chargers is becoming more and more modernized. However, due to the limitation of single-sided and double-sided mixed packaging of the product itself, the assembly of power chargers must be made of surface mount (SMT) and through-hole plug-in. (THT) consists of two different processes. Due to the continuous development of electronic processing in the direction of miniaturization and high integration, the electronic components used in power chargers are also getting smaller and smaller, and the assembly density of electronic components is getting higher and higher, especially in In the THT process, the solder paste is easy to drop when the components are inserted, resulting in a more serious phenomenon of virtual soldering, so the requirements for the solder paste are getting higher and higher, especially for the post-soldering reliability of the solder paste. The device requires that the components are not resistant to high temperature. In lead-free solder, the preferred alloy composition is Sn42Bi58. The solder paste is generally composed of 35-58% resin (KE-604), 1-6% thixotropic agent (such as thixotropic agent) Variable agent 6650), 35-55% by mass of solvent (such as diethylene glycol hexyl ether), 1.5-7% by mass of active agent (such as succinic acid, 24 acid, etc.), the current type of solder paste is difficult to To meet the above requirements, there are mainly the following deficiencies in the welding of power chargers:

[0003] 1. The solder paste of the plug-in components is easy to fall off during the plug-in process, resulting in false soldering;

[0004] 2. After using the solder paste for 2-3 hours, there will be more tin beads in the post-soldering residue, especially between the pads with small spacing, there will be a short circuit phenomenon;

[0005] 3. After the solder paste is used for 2-3 hours, the solder paste dries up, resulting in less tin in the solder, less tin in the solder joints, resulting in false soldering