摘要
单排焊端的QFN焊接工艺趋于成熟,而双排及多排QFN器件给组装过程带来了很大挑战。生产中主要难点在于此类器件与其他较大型器件混装,对焊膏量、共面性的要求比较苛刻。通过分析焊膏印刷原理,同时在比对芯片焊端与PCB焊盘尺寸的基础上,采用调整模板开孔的方式来改善焊膏印刷,使焊接效果达到品质要求。介绍了PCB焊盘阻焊开孔及表面处理工艺、丝印参数在组装过程中的影响以及多排QFN返修工艺。
The soldering technology of single row pins QFN is mature, but the soldering technology of double or multi row pins QFN has brought great challenges. The main dififculties in production are that the requirements for paste volume and coplanarity are Very strict when PCBs has other large devices. Through the analysis of solder paste printing principle and comparison between chip termination size and PCB pad size, the soldering effect meet the quality requirements by adjusting stencil apertures to improve the solder paste print. Introduce the inlfuence of solder mask apertures, surface treatment, paste print on soldering effect, and repair methods of multi-row pins QFN.
出处
《电子工艺技术》
2014年第6期353-357,共5页
Electronics Process Technology
关键词
模板开孔
非阻焊膜定义焊盘
金相切片
X射线检测
Stencil aperture
Non-solder mask defined pads
Cross-section
X-Ray inspection
