Scaling powder for no-clean lead-free low-silver welding paste

Abstract

The invention discloses scaling powder for no-clean lead-free low-silver welding paste. The scaling powder comprises, by weight percentage, 3-13% of active agent, 0.2-1.5% of surface active agent, 0.2-3.0% of emulgator, 3.0-10.0% of thixotropic agent, 3-8% of film-forming agent, 0.1-1% of antioxidant, 0.1-0.5% of corrosion inhibitor and the rest of solvent. The active agent is composed of four or five components in succinic acid, oxalic acid, salicylic acid, glutaric acid, citric acid, adipic acid, lactic acid, benzoic acid, malic acid and triethanolamine. The scaling powder for the no-clean lead-free low silver welding paste does not contain halogen, the corrosion to a circuit board is greatly lowered, the printing quality of the welding paste is good without bridging or turned-down edges, a welding point is good in forming after returning, the brazing connecting defect is greatly lowered, the residue is small without solder balls, the cleaning is not needed, the welding paste is directly used for assembling, the Sn-0.45 Ag-0.68 Cu or Sn-0.3 Ag-0.7 Cu low silver welding paste manufactured by using the scaling powder does not contain the halogen and rosin, the organic chemistry smoke is small, and the pollution to the environment is small.

Description

technical field [0001] The invention relates to a flux, especially a flux for no-cleaning lead-free low-silver solder paste, which is suitable for preparing conventional lead-free low-silver solder such as Sn-0.45Ag-0.68Cu or Sn-0.3Ag-0.7Cu Paste products. [0002] Background technique [0003] The solder paste used in surface mount (SMT) plays an important role in the whole soldering process. As an auxiliary material in solder paste (mass fraction is 10%~20%), flux can not only provide excellent soldering performance, but also directly affect the printing performance and storage life of solder paste. Therefore, the quality of flux directly affects the entire process and product quality of SMT. There are many types of fluxes for solder paste, and their component ratios and applicability are different. Although traditional rosin-based fluxes can provide good fluxing performance, most of these fluxes have high solid content, resulting in many residues after soldering and p...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problems that the existing lead-free solder paste needs to be cleaned after soldering, the workload is increased, and the problem of strong corrosion and environmental pollution due to the halogen ion is contained, the present invention provides a lead-free and low-silver solder paste. no-clean flux