Characterization of chip scale packaging materials

摘要

The mechanical stabiltiy of Chip Scale Packages (CSP) used in surface mount technology is primary concern. The dominant issues are package warpage and solder fatigue in solder joints under cyclic loads. To address these issues, molding compound and die attach film were characterized with finite element mehod which employed a viscoelastic and viscoplastic constitutive model. The model was verified with experiments on package warpage, PCB warpage and solder joint reliabiltiy. Aftr the correlation was observed, the effect of molding compound and die attach film on package warpage and solder joint reliabiltiy was investigated. It was found that package warpage termendously affected solder joint reliabiltiy was investigated. It was found that package warpage tremendowsly affected solder joint reliabiltiy. Furthermore, a die attach film was developed based on results of the modeling. CSP with the developed die attach film are robust and capable of withstanding the thermal stresses, humidity and high temperatures encountered in typeicla package assembly and die attach processes. Also, a lead free solder is discussed based on the results of creep testing. This paper presents the viscoelastic and viscoplastic constitutive modle and its verification, the optimum material properties, the experimental and simulated reliability and performance results of the u*BGA packages, and the lead free solder creep.