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|Effect of Sealing Material on the Reliability of Direct-Bond-Copper Substrates|
|Keywords: Direct-Bond-Copper(DBC), Reliability, Thermal Cycling|
|Direct-bond-copper (DBC) is widely used as a substrate material for power electronic packaging. However, when subjected to high temperature cycling, as pointed out by previous researches, the reliability lifetime of DBC is greatly reduced. It has also been reported that creating step-edges and seal-edges can significantly improve the reliability lifetime. In this work, the reliability of seal-edged and non-seal-edged DBC substrates are compared under a cycling condition of -55°C - 200°C. Also, the effect of interfacial adhesion between sealing material and DBC on the reliability is investigated. Parylene HT and R-2188 were used as the sealing material. CF1-135 was used as the adhesion promoter. During temperature cycling, one out of the three non-seal-edged substrates failed after 100 cycles; the other two failed after 150 cycles. When coated with parylene HT, failure was postponed to 300 cycles under the same condition. It was proven that a 10 μm parylene HT film can double the reliability lifetime of DBC substrates under temperature cycling condition of -55°C - 200°C. It was also discovered that parylene HT peeled off from DBC surfaces approximately 100 cycles before failure. This led to the hypothesis that strong interfacial adhesion may further improve substrate lifetime. Therefore, to evaluate the effect of interfacial adhesion on reliability, another experiment was designed. R-2188 silicone elastomer had been used as the sealing material. CF1-135 silane coupler was used to improve adhesion strength between R-2188 and DBCs. Temperature cycling of -55°C - 200°C had been performed to R-2188 coated DBC with and without CF1-135. The reliability of each is being compared. The results will be reported in the full paper.|
|Yiying Yao, Student