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Stencil mask design method and under bump metallurgy for C4 solder bump

Authors Xiao, Guo Wei HKUST affiliated (currently or previously)
Chan, Philip Ching-Ho HKUST affiliated (currently or previously)
Issue Date 2006-11-14
Source US Patent , 7,135,355 B2, 2006
Summary A method for the fine-pitch stencil mask design for stencil printing bumping technology for eutectic Sn/Pb and lead-free solder material is described. In the method, a reflowing enhancement layer is introduced to improve the solder quality and reduce the pitch of solder bumps. The method of forming the layer is described as well as the forming method of matching under-bump metallurgy layer. The method of stencil mask design can match various sizes and pitch of the solder bumps. The designed mask is fixed on the stencil printer to deposit the solder materials with the required patterns. This method can increase the solder paste volume to increase the height of solder bumps after the reflowing process.
Language English
Format Patent
Access View details of TTC.PA.212S via HKUST Technology Transfer Center
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US7135355TTC.PA.0212_20061222.pdf 292802 B Adobe PDF