Statistical Evaluation for Type-6 Lead-Free Solder Paste Down to 200-Microns Pitch with Type 6 Pb-free Solder Paster
Recent advances in chip scale packaging technologies have prompted a rapid increase in the density of solder joints in microelectronics products. As the industry pushes towards utilizing this packaging technology due to the benefits for miniaturization, reduction in production materials, requirements for high speed communication and eventual decrease in manufacturing costs further reductions in the pitch size are likely, leading to joint structures exhibiting sub-200μm dimensions. Stencil printing for flip chip packaging using fine particle solder pastes is a low cost and flexible assembly solution for flip chip solder joint interconnects. In addition the associated cost and process properties makes Wafer Bumping by stencil printing solder paste an attractive alternative compared to other bumping technologies.However, for ultra fine pitch printing applications, consistency and yield are determined by a combination of variables that are involved in the stencil manufacturing, paste formulation, and the solder paste printing. Recent improvements have been made to enable this process as a viable production process for volume production. The key parameters for this process are clearly defined in this study for pb-free alloys.The WEEE and RoHS Directives, outlining targets for electronic equipment re-use and recycling, have indicated to the electronics manufacturing industry that an inevitable change to replace the Sn-Pb solders with Pb frees alloys. For that reason this paper reports his paper that solder paste printing with lead free solder paste has been achieved at pitches ranging from 180-200 microns pitch using Pb-free solder paste with IPC type-6 (15-5μm) powder particles . The results showsthat repeatable paste deposits can be produced at ultra fine pitch for certain paste types, stencil designs and manufacturing methods.This project investigates the print performance of four type 6 SAC-solder pastes, from 3 different suppliers in combination with different stencil manufacturing technologies:· State of the Art laser cut stencil,· conventional electroformed stencil and· a precision microengineered stencil.· In particular the key criteria evaluated in this study for each stencil and paste type are:· Bump height and coplanarity · Line resolution (minimal printable apertures) and achievable pitch· Paste release & Frequency of cleaning· Hot slump
fine pitch printing type 6 solder paste lead free bump height
T.Krebs A.Brand Richard Lathrop R.W.Kay T.Wang I.Roney
W, C.Heraeus GmbH, Contact Materials Division, Heraeusstrasse 12-14, 63250 Hanau, Germany Micro Stencil Limited.Starlaw Park, Starlaw Road, Livingston, EH54 8SF, Scotland, UK
国际会议
Chinas Premier SMT & MPT Event(2007年中国国际表面贴装和微组装技术大会)
上海
英文
134-162
2007-03-22（万方平台首次上网日期，不代表论文的发表时间）