关键词: 可润湿侧翼, 试验设计法, 切割深度, 框架设计

Abstract: This study investigates burr defects formed during the singulation of wettable flank (WF) quad flat no-lead (QFN) packages. Defect analysis indicated that copper burrs and filings generated in the first singulation were difficult to eliminate. During subsequent plating, these residues were encapsulated within the tin layer, leading to an increase in Dambar width beyond design specifications. In the second singulation step, blade compression readily induced tin burrs. The singulation parameters were optimized using a design of experiment (DOE) approach. Furthermore, the cutting blade and frame design were improved based on experimental findings. The results demonstrated that a reduced cutting depth, a self-sharpening blade, and a narrower Dambar width collectively enhanced the WFQFN product yield and effectively mitigated burr formation on the wettable flank structure.

Key words: wettable flank, doe, cut depth, lead frame design