Heat-resistant die-attach with cold-rolled Ag sheet

Noh, Seungjun; Choe, Chanyang; Chen, Chuantong; Suganuma, Katsuaki

doi:10.7567/apex.11.016501

Cited by 21 publications

(4 citation statements)

References 36 publications

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“…3) For this reason, wide-bandgap (WBG) semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) are emerging in modern transportation equipment industries as the next generation of semiconductors. 4) These WBG semiconductors enable power electronic devices to operate at much higher temperatures (>250 °C) than traditional Si-based power devices (<150 °C), 5,6) because they are theoretically capable of operating at high temperatures above 500 °C at switching frequencies in the range 10-100 GHz and the increased power densities of power modules. 3) WBG semiconductors can also ultimately maximize the efficiency of the system by reducing the volume of the cooling system.…”

Section: Introductionmentioning

confidence: 99%

Thermal shock reliability of a GaN die-attach module on DBA substrate with Ti/Ag metallization by using micron/submicron Ag sinter paste

Kim

Chen

Pei³

et al. 2019

Jpn. J. Appl. Phys.

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This study was carried out to evaluate the reliability of GaN die-attached on a direct bonded aluminum (DBA) substrate with Ag sinter joining in up to 1000 harsh thermal shock cycles over a temperature range from −50 °C to 250 °C. For joining the die-attached structure, metallized Ti/Ag was prepared first on the substrates of DBA and GaN chips. A GaN die and DBA substrate were bonded by a micron/submicron Ag sinter paste in air at 250 °C without pressure. The initial die shear strength of the GaN/DBA joint structure, above 33 MPa, was retained up to 250 cycles and then gradually decreased up to 1000 cycles. Microstructural observation by field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy showed a crack growing inside the Ag/Al bonding interface during thermal cycles due to the large plastic deformation of the Al layer. In addition, with the aid of simulations based on the finite element method, the damage mechanism is discussed in further detail, including the Al grain boundary effect. This study systematically revealed that the mechanism of thermal shock damage of a GaN/DBA module with an Ag sinter joining structure suggests that it can prevent severe damage during thermal shocks in high-temperature applications.

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Section: Introductionmentioning

confidence: 99%

Thermal shock reliability of a GaN die-attach module on DBA substrate with Ti/Ag metallization by using micron/submicron Ag sinter paste

Kim

Chen

Pei³

et al. 2019

Jpn. J. Appl. Phys.

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“…The high purity Al sheet bonding technology introduced in this study is more cost-efficient and has a simpler bonding process compared with the Ag thin film bonding technology and Ag sinter paste joining. In addition, the melting point is Ag thin film 25,26 1 Table 1. Material properties of pure Al sheet die-attach compared with other materials.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, a solid-state bonding technology that uses porous Ag [22][23][24] or Ag foils 25,26 has been reported for high-temperature applications. The bonding mechanism is attributed to solid interface inter-diffusion, which requires high-temperature or high-pressure conditions 24,26 , which contribute to high costs. A direct bonding method of Ag coating on the Si chip surface has been reported.…”

mentioning

confidence: 99%

Low temperature SiC die-attach bonding technology by hillocks generation on Al sheet surface with stress self-generation and self-release

Chen

Suganuma

2020

Sci Rep

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this paper introduced an approach of die-attach bonding technology based on a low-cost high-purity aluminum (99.99%) sheet in a silicon carbide (SiC)/direct bonded aluminum (DBA) power module. Both sides of an Al sheet were sputtered by a thin Ti and Ag layer, which generated a tensile stress of 166 MPa on the Al surface. After heating, the Al surface displayed a large quantity of Ag hillocks by stress selfrelease due to the coefficient of thermal expansion (CTE) mismatch among Al, Ti, and Ag. The SiC/Al sheet/DBA substrate interfaces were bridged by the generation of these hillocks, which correspond to a robust shear strength of 33.4 MPa in a low-temperature process. Hillocks generation and the interface bonding mechanism by surface stress self-generation and self-release were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The shear strength remains constant at 32.1 MPa after high-temperature storage at 250 °C for 500 h, which suggests that the Al sheet possesses excellent high-heat resistance and thermal stability. this novel approach of die-attach bonding technology serves as an attractive alternative for Sic power devices that require high-temperature performance. Silicon carbide (SiC) forms a next-generation power semiconductor that realizes innovative energy saving in all types of electronic equipment, such as information communication equipment, electric vehicles, and electric railways 1-4. Next-generation super-heat-resistant packaging needs to secure reliability at extremely high operating temperatures (maximum temperature of 250 °C), which are substantially higher than the operating temperature of conventional Si devices (maximum temperature of 150 °C). Although the junction temperature of SiC is 250 °C, SiC can operate at high temperatures. The heat resistance of each part that constitutes the module is lower than 175 °C, which is representative of most solder die-attach materials. To address these challenges, a novel class of die-attach technologies is required due to the processability, compliance, and cost of solders. However, the electrical and thermal properties must match those of a pure metal. SiC power device modules comprise several components, including terminals, a SiC die, direct bonded copper (DBC) or direct bonded aluminum (DBA) substrate, and a heat sink. The bonding technology of SiC die devices, which can be employed for high operating temperature mounting, can be divided into three categories: (1) high melting point solder bonding 5-7 , (2) solid-liquid inter-diffusion bonding (SLID) 8-10 , (3) sinter silver paste joining 11-15 or copper paste joining 16,17. SLID bonding technology has a few advantages, such as a relatively short bonding time and some surface roughness tolerance; however, it is generally limited to material combinations with a favorable phase diagram 17 and interface voids generation 18. The use of sintered Ag paste as a bonding layer has received considerable attention due to its sup...

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“…Since these WBG semiconductors have superior properties, kind of a wide band gap (>3 eV), a high critical electric field (>3 MV/cm) and a high saturation velocity (>2 × 10 7 cm/s), SiC and GaN can enable to overcome the ultimate performances reached by silicon (Si) based devices, in terms of power conversion efficiency [3]. In addition, WBG semiconductor devices can be operating much higher temperatures (>250 °C) than Si based devices (<150 °C) [4,5,6,7,8], this means massive, complex and heavy cooling systems can be eliminated from power conversion systems. Inverters and converters automotive components can be change to smaller by the simply heat dissipation design of in the high temperature environments [9].…”

Section: Introductionmentioning

confidence: 99%

Measurement of Heat Dissipation and Thermal-Stability of Power Modules on DBC Substrates with Various Ceramics by SiC Micro-Heater Chip System and Ag Sinter Joining

et al. 2019

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This study introduced the SiC micro-heater chip as a novel thermal evaluation device for next-generation power modules and to evaluate the heat resistant performance of direct bonded copper (DBC) substrate with aluminum nitride (AlN-DBC), aluminum oxide (DBC-Al2O3) and silicon nitride (Si3N4-DBC) ceramics middle layer. The SiC micro-heater chips were structurally sound bonded on the two types of DBC substrates by Ag sinter paste and Au wire was used to interconnect the SiC and DBC substrate. The SiC micro-heater chip power modules were fixed on a water-cooling plate by a thermal interface material (TIM), a steady-state thermal resistance measurement and a power cycling test were successfully conducted. As a result, the thermal resistance of the SiC micro-heater chip power modules on the DBC-Al2O3 substrate at power over 200 W was about twice higher than DBC-Si3N4 and also higher than DBC-AlN. In addition, during the power cycle test, DBC-Al2O3 was stopped after 1000 cycles due to Pt heater pattern line was partially broken induced by the excessive rise in thermal resistance, but DBC-Si3N4 and DBC-AlN specimens were subjected to more than 20,000 cycles and not noticeable physical failure was found in both of the SiC chip and DBC substrates by a x-ray observation. The results indicated that AlN-DBC can be as an optimization substrate for the best heat dissipation/durability in wide band-gap (WBG) power devices. Our results provide an important index for industries demanding higher power and temperature power electronics.

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Heat-resistant die-attach with cold-rolled Ag sheet

Cited by 21 publications

References 36 publications

Thermal shock reliability of a GaN die-attach module on DBA substrate with Ti/Ag metallization by using micron/submicron Ag sinter paste

Thermal shock reliability of a GaN die-attach module on DBA substrate with Ti/Ag metallization by using micron/submicron Ag sinter paste

Low temperature SiC die-attach bonding technology by hillocks generation on Al sheet surface with stress self-generation and self-release

Measurement of Heat Dissipation and Thermal-Stability of Power Modules on DBC Substrates with Various Ceramics by SiC Micro-Heater Chip System and Ag Sinter Joining

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