Micro Device Fine-Pin Soldering, Small Pin Components SMT Process

Bridging on Fine-Pin Chips in High-Speed SMT Production Lines: A Yield-Killing Defect

Bridging is the core defect causing a sharp drop in yield for fine-pitch chips (such as 0.4mm pitch QFN and 0.3mm pitch BGA) in high-speed SMT production lines. Its causes are concentrated in the combined effect of solder paste printing offset, mismatch in stencil aperture design, and fluctuations in placement accuracy. Actual measurements on Jia Jinyuan production lines show that bridging accounts for 68% of total solder joint defects, far exceeding cold solder joints and tombstoning.