Designed Experiment to Determine the Reliability of Various Commercial Plating Baths and the Key Factors Affecting Whisker Formation

• Main Authors: Cheng-Hsiung Hsu, 徐政雄
• Other Authors: SHIA-CHUNG CHEN
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/52321023880705256847

碩士 === 中原大學 === 機械工程研究所 === 94 === Abstract In order to develop a reliable Lead-free substitutes applying on soldering application for electrical component, six hazardous substances includes Lead shall be restricted in a bittiest level claims by RoHS since July 1st 2006. Traditional SnPb was implementing on soldering material, not only to downgrade the melt temperature of solder, but also to restrain the Sn whisker as bridge to avoid circuit shorting on equipment. The response variables included whisker density, whisker length, solderability, and solder joint reliability. We used total whisker length for data analysis but also measured “effective whisker length” for comparison under eight conditions. The eight main input variables for this DOE included; tin baths-3 levels, nickel thickness-2 levels, topcoat type-2 levels, topcoat thickness-2 levels, preconditioning-2 levels, aging environment-3 levels, aging duration-7 levels, and observed stress zones-4 levels. We also collected some data on no nickel versus nickel. Our test vehicle was a surface mount R/A header. We statistically analyzed all results that were collected monthly over a six-month period and were able to draw conclusions about which input variables significantly retarded or promoted whisker growth. The results present five times on whisker quantity between SnPb and pure Sn, and one-fifth on whisker length. Moreover, an effective and rapid method was found to speed up the whisker growth with thermal cycle and heat & humidity tests.