| Summary: | 碩士 === 國立彰化師範大學 === 機電工程學系 === 98 === The reliability of BGA (Ball Grid Array) products is one of the critical factors, which influence the lifetime of electronic products, and there are many literatures probing into the failure causes by temperature fatigue. To foresee the lifetime of BGA, various acceleration models were established and studied in succession. In this study our purpose is to prove that the acceleration factors in this model will be relevant to the parameters of chip design and package type. Thus we focus on the parameters such as Sphere size, Ball pitch, Package size and Die size and so on, which apparently affect the acceleration models.
There are different package types applied to this analysis, for example, MAPPBGA, CBGA, FCBGA and LGA, etc. Based upon original Norris-Landzberg[1] formula, we also introduce 2 parameters into this study, frequency and maximum temperature Tmax via the data of temperature cycle failure test to acquire the AF(Acceleration factor) data. Furthermore, from [Newton’s law of cooling], we try to find the correlation among thermal conductivity, acceleration models and acceleration factors, and the effects of each shape parameter on acceleration factors.
Our study demonstrates that the acceleration model made of SAC (Sn/Ag/Cu) solder material under the same package size has the larger acceleration factor than that of the other material. The thermal conductivity value of package is between air (value 0.024) and fiber board (FR4) (value 0.3). As regards package size, thermal conductivity is inversely proportional to thermal resistance trend. Finally, technical literatures [2][3] are quoted to describe the relationships between AF and thermal resistance to package size and die size in detail.
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