HotLine:
The traditional tin-lead solder is a standard material for connecting components and printed circuit boards because of its low cost, easy soldering, beautiful shape, good physical, mechanical and metallurgical properties, and has formed a set of application process, which has long been favored by electronic merchants. The results show that Pb plays the following important roles in Sn-Pb solder:
(1) Reducing surface tension is beneficial to infiltration;
(2) It can prevent the occurrence of tin epidemic. The so-called tin epidemic refers to the phase change from free tin (G-Pb) to gray tin (Z-Pb), which causes 26 volume expansion below 13 C.
(3) Promote rapid bonding between solder and welded components.
Although lead-tin solder has so many advantages, because lead is a highly toxic substance, the long-term use of lead-containing solder will bring serious harm to human health and living environment. Therefore, the voice of restricting and prohibiting the use of lead-containing solder is growing. Governments have formulated corresponding regulations to restrict the use of materials and waste disposal of electronic products, so as to make electronic packaging environmentally friendly. It has become a global trend. In addition, lead-free technology, due to the difference of solder and the adjustment of welding process parameters, will inevitably have a certain impact on the reliability of solder joints. SMT and MCM solder joints directly realize electrical and mechanical connections between heterogeneous materials (mainly withstanding shear strain). The quality and reliability of SMT and MCM solder joints largely determine the quality of electronic products. Therefore, more and more attention has been paid to the reliability of lead-free solder joints.
