Thermal Fatigue Life of Soldered Joints of Flat Package.
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概要
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Thermal fatigue life of soldered joints of flat package (FP) -LSI on printed circuit boards is quantitatively estimated by observation of the crack length in thermal cycle tests and the crack propagation mechanism of solder joints is proposed. The main factor causing the crack propagation in soldered joints of the FP-LSI with ceramic packaging is bending strain of the lead opening to heel of the joints when the temperature changes from high to low. The crack length of FP-LSI soldered joints increases approximately proportional to the thermal cycles. Effects of the lead stiffness, the thermal expansion coefficient of printed circuit boards, the defective mode of soldered joints, the solder thickness, the thermal cycle conditions and the thermal fatigue with creep by spring back effect of the lead on the crack propagation are clarified. Macro analysis method by using mean equivalent stress is useful for the evaluation of the soldered joints reliability.
- 社団法人 エレクトロニクス実装学会の論文