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From now on, on the high-density double-sided mounting substrates represented by mobile phones and notebooks, due to the low heat-resistant temperature of BGA packaged IC, aluminium electrolytic capacitor and large connector connected with them, and restricted by the characteristics of substrates, device configurations and wiring patterns, as well as the current reflow soldering conditions have not changed greatly, the melting point phase is used as far as possible. Near solder is ideal. Therefore, an alloy solder consisting of silver, bismuth and zinc in tin has been developed. However, these solders have poor properties except low melting point, and sometimes they can not even be used. At the same time, it is necessary to improve the manufacturing equipment and re-explore the surface treatment of the connecting substrates. In addition, in the production of reflow welding and flow welding hybrid installation of substrates, measures must be taken to alleviate the stress caused by thermal expansion and warping of substrates, resulting in welded joints. Otherwise, the reliability of the connection will not be guaranteed and will cause trouble.
In addition, the solder used for flow welding and impregnation welding in commonly used solder tanks can be used if it can be operated at the current welding temperature, even for alloys with higher melting points such as tin, copper, tin and silver, as long as the fluidity can be guaranteed. In fact, it is very important to analyze the change of properties according to the reliability and composition change of solder and impurity mixing. Of course, it will take some time to explore these contents.
In addition, the evaluation of patents and costs is also indispensable. No matter which one is missing, it can not be used as a reassuring permanent material. As a result, large users are cautious in determining the composition, but time varies. The process of reassessing lead-free solders from alloy composition is not consistent with the deadline for lead-containing solders to be used. As a result, only a small number of solders of practical value have been used.
This article is from http://www.www.langleyyellowpages.com.
