电子产品在焊接过程中的可靠性探究

制备了一种新型Sn-9Zn-2.5Bi-1.5In钎料，开发了一套波峰焊氮气保护系统，考察了该钎料在不同氧含量的环境下的焊接质量. 结果表明，开发的氮气保护系统通过增加氮气流量可以将焊接区域内的动态氧含量降低到0.06%以下. 降低焊接区氧含量，可显著减少桥连、填充不良、气孔3类缺陷的数量，将不良率控制在0.20%以内. 在氧含量0.50%的临界值以下，该钎料可在锡炉设定温度为225 ℃的条件下进行低温焊接，焊接效果满足规模化生产需求. 通过能谱分析发现氧化物表面Zn元素含量比Sn-9Zn-2.5Bi-1.5In钎料升高84.9%，Zn元素的易氧化倾向是导致钎料形成大量氧化渣的主要原因. 降低焊接区域的氧含量可以有效抑制氧化渣的形成.采用氮气保护的方法可以解决Sn-Zn钎料在高氧环境下易出现的焊接缺陷问题，从而实现225 ℃低温波峰焊.

Research on reliability of electronic products in welding process

A new Sn-9Zn-2.5Bi-1.5In solder is prepared, a wave soldering nitrogen protection system is developed, and the soldering quality of the solder under different oxygen content is investigated. The results show that the modified nitrogen protection system can reduce the dynamic oxygen content to less than 0.06% by increasing the nitrogen flow. Reducing O₂ content in the soldering zone can significantly decrease the number of bridging, poor filling and pore defects, and the failure rate is controlled within 0.20%. Under the critical value of 0.50% oxygen content, the joint can be soldered at low temperature under the condition of 225 ℃ setting temperature. The soldering quality can meet the needs of large-scale production. EDS analysis shows that the content of Zn in the oxide dregs is increased by 84.9% compared with the original Sn-9Zn-2.5Bi-1.5In alloy, and the easy oxidation tendency of Zn leads to the formation of a large number of oxide slags. Reducing the oxygen content in the soldering zone can restrain the formation of oxide slags on the wave's surface. Nitrogen protection can solve the soldering defects of Sn-Zn alloy to realize low-temperature wave soldering at 225 ℃.