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In this study, intelligent power module (IPM) with body size of 40mm × 40mm is developed and its stress and reliability are investigated through finite element analysis (FEA) considering power cycling loading condition. Mechanical modeling and simulation for IPM package subjected to power cycling are conducted to help material selection such as epo...
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... Critical solder joints location are identified and predicted based on FEA simulation results. To improve solder joint reliability and reduce package stress, parametric study on material selection is conducted including 6 EMC, 4 DA, and 4 TIM materials. Final material selection is recommended for IPM test vehicle based on FEA simulation results. Fig. 1 shows expose view for IPM package. In the IPM test vehicle, 2 SiC chips with body size of 3.1mm × 5.9mm × 0.18mm each are mounted onto Cu lead frame with die attach (DA) material. Chip gate and source are connected to Cu lead frame through solder and Cu clip 1 and Cu clip 2, respectively. After chip attachment, compression molding ...
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... is not significant. Thin TIM3 (50µm) reduces the maximum chip stress. For overall low stress of SIC chip, DA1, EMC1 or EMC3 are recommended. Molding compound has large stress at the interfacial area with SiC chip where temperature is high and temperature variation is severe. Stress varies with power on and off during power cycling, as shown in Fig. 10. Stress reached its peak value before power is off. Fig. 11 shows the effect of packaging material on first principle stress of mold compound. Mold compound is one important parameter affecting itself stress. EMC3 leads to lower stress due to its lower modulus and molding temperature. TIM3 leads to slightly higher stress due to its ...
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... chip stress. For overall low stress of SIC chip, DA1, EMC1 or EMC3 are recommended. Molding compound has large stress at the interfacial area with SiC chip where temperature is high and temperature variation is severe. Stress varies with power on and off during power cycling, as shown in Fig. 10. Stress reached its peak value before power is off. Fig. 11 shows the effect of packaging material on first principle stress of mold compound. Mold compound is one important parameter affecting itself stress. EMC3 leads to lower stress due to its lower modulus and molding temperature. TIM3 leads to slightly higher stress due to its poor thermal conductivity and low modulus. Thin TIM layer ...
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... temperature. TIM3 leads to slightly higher stress due to its poor thermal conductivity and low modulus. Thin TIM layer (50µm) looks no help to reduce the maximum EMC stress. Effect of DA on stress is negligible. Die attach has large stress at the edge area than other locations. Stress varies with power on and off during power cycling, as shown in Fig. 12. Stress reached its peak value before power is on because high bonding temperature is set as stress free temperature. First principle stress and von Mises stress follow the similar profile. Fig. 13 shows the effect of packaging material on the first principle stress of die attach. Die attach itself is one important parameter affecting ...
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... negligible. Die attach has large stress at the edge area than other locations. Stress varies with power on and off during power cycling, as shown in Fig. 12. Stress reached its peak value before power is on because high bonding temperature is set as stress free temperature. First principle stress and von Mises stress follow the similar profile. Fig. 13 shows the effect of packaging material on the first principle stress of die attach. Die attach itself is one important parameter affecting its stress. DA1 leads to lower DA stress due to its lower modulus and lower bonding temperature. Effects of TIM and EMC materials on DA stress are not significant. Thin TIM layer (50µm) looks no ...
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... one important parameter affecting its stress. DA1 leads to lower DA stress due to its lower modulus and lower bonding temperature. Effects of TIM and EMC materials on DA stress are not significant. Thin TIM layer (50µm) looks no help to reduce the maximum DA stress. To reduce DA stress, DA1 is recommended and it also leads to low chip stress. . Fig. 13. Effect of packaging material on stress of die ...
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... High Ag content lead-free solder is used as solder joint material in IPM package to improve reliability when subjected to power cycling. Temperature dependent Young's modulus is modelled for solder material [10]. Elastic-creep model of solder is adopted and creep strain energy density is used as failure control parameter for life prediction [11]. Fig. 14 shows creep strain energy density of solder joint. Solder joint between chip source (right chip) and Cu clip shows the highest creep strain energy density, which means the lowest fatigue life under power cycling condition. Fig. 14. Creep strain energy density of solder ...
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... of solder is adopted and creep strain energy density is used as failure control parameter for life prediction [11]. Fig. 14 shows creep strain energy density of solder joint. Solder joint between chip source (right chip) and Cu clip shows the highest creep strain energy density, which means the lowest fatigue life under power cycling condition. Fig. 14. Creep strain energy density of solder ...
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... for life prediction using energy-based fatigue life model [8,9]. Solder joints between Cu clip and Cu lead frame have very long fatigue life under power cycling condition due to matched CTE among solder, Cu frame and Cu clip. Therefore, solder joint life prediction will be focused on solder joints at both chip gate and chip source as mentioned in Fig. 14. Fig. 15 shows fatigue life of solder joints at chip source for different packaging materials. Solder joints located at the left chip have higher life than those at the right chip for all cases due to low temperature variation. TIM material has significant effect on PCT life of solder joint at chip source. TIM3 leads to the lowest life ...
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... prediction using energy-based fatigue life model [8,9]. Solder joints between Cu clip and Cu lead frame have very long fatigue life under power cycling condition due to matched CTE among solder, Cu frame and Cu clip. Therefore, solder joint life prediction will be focused on solder joints at both chip gate and chip source as mentioned in Fig. 14. Fig. 15 shows fatigue life of solder joints at chip source for different packaging materials. Solder joints located at the left chip have higher life than those at the right chip for all cases due to low temperature variation. TIM material has significant effect on PCT life of solder joint at chip source. TIM3 leads to the lowest life of ...
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... and EMC5 lead to slightly higher PCT life of solder joint maybe due to their lower CTE and slightly higher modulus. 16 shows fatigue life of solder joints at chip gate for different packaging materials. Solder joints located at the left chip also have higher life than those at the right chip. ...
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... life prediction results, solder joint at chip source is critical one, which should be carefully designed in terms of solder material, other packaging material selection, and structure design. High temperature solders, such as SnSb, sintered Ag or Cu, are needed to further improve reliability of advanced IPM package, which will be the future work. Fig. 16. Effect of packaging material on power cycling fatigue life of solder joint at chip ...
