Influence of IC substrate surface finish joints with Pb-free solder in reliability test

• Main Authors: Lin, Yen-Yi, 林延益
• Other Authors: Chang, Yung-Chia
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/06915771519535249786

碩士 === 國立交通大學 === 管理學院碩士在職專班工業工程與管理組 === 98 === For electronic packaging, BGA (Ball Grid Array) substrate connects to PCB (Printed Circuits Board) by using solder ball welding process, solder joints may cause cracks while the electronic components get an accidental drop. The solder joints strength depends upon the strength of IMC (Inter-Metallic Compound) for two metal materials welding process. However, the welding strength of IMC is determined by surface finish process of basic materials and compositions of the solder ball materials. In this connection, it is very important to select a proper surface finish process of basic material and use proper solder ball to achieve the most welding strength. That will be the key consideration factors for those portable electronic products avoiding any negative impact by accidental drop by users. This study is done by DOE(Design and Analysis of Experiment) to try to find out the most proper weld compositions of the variety of Pb-free solder balls and surface finish technologies in order to achieve the best welding strength results. The factors of this DOE are Pb-free solder balls and the surface finish technologies; there are four levels for Pb-free solder balls, SAC105(Sn98.5%-Ag1%-Cu0.5%), SAC305(Sn96.5%-Ag3%-Cu0.5%), SAC405(Sn95.5%-Ag4%-Cu0.5%) and SN96.5-Ag3.5; and four levels for surface finish technologies; IT (Immersion Tin, ), ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold), ENEP (Electroless Nickel Electroless Palladium) and OSP (Organic Solderability Preservatives) . The weld time is designed as an block which we may maintain the most welding strength during multi-reflow process. Therefore, it is defined to keep the experimental process by randomized complete block design for these two factors study. This experiment has demonstrated that Pb-free SAC405 collocates surface finish IT、ENEPIG or ENEP to own best welding strength after welding process of the variety of Pb-free solder balls and surface finish technologies.