Ag 및 Cu 입자의 페이스트화를 통한 무가압 소결접합 기술
Pressureless Sintering Technologies Using Ag and Cu-based Pastes
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초록
전기차 시장의 성장과 신재생 에너지 확대에 따라 파워모듈 및 차세대 WBG 파워반도체의 수요가 급증하고있다. 특히 SiC 파워반도체는 고온 신뢰성 확보를 위해 고온 die-attach 소재와 접합이 필수적이며, 기존 솔더를 대체할Ag 또는 Cu 기반 소결접합 소재의 개발이 요구된다. 가압 공정 대비 무가압 소결접합 공정은 산업적 파급력이 크지만, 긴 공정시간과 낮은 접합 밀도 문제를 해결해야 한다. 따라서, 본 논문에서는 그 동안 보고된 보다 효과적인 Ag 및 Cu 필러 기반 무가압 소결접합 방안들을 화학적 접근 측면, 입자 최적화 측면, 기타 개선 방안 측면으로 구분하여 리뷰하고, 제시된 연구 결과 및 특징들을 상호 비교, 분석하고자 하였다. Ag 나노입자를 사용한 무가압 소결접합 기술은 축적된 연구 경험을 바탕으로 빠른 시간 내 높은 접합 강도와 치밀한 접합부를 구현할 수 있는 방안들이 제시되었으며, 따라서 향후 양산 공정 적용 가능성이 높다. 반면, Cu 입자 기반의 무가압 소결접합은 아직 초기 연구 단계에 있으나, 최근 질소 분위기에서의 초미세 Cu 나노입자의 우수한 소결 성과가 보고되었다. 이를 통해 Cu계 무가압 접합기술의 발전이 기대되며, 관련 연구가 활발히 진행될 전망이다.
Abstract
The demand for power modules and next-generation WBG power semiconductors is surging owing to the growth of the electric vehicle market and the expansion of renewable energy. In particular, SiC power semiconductors require high-temperature die-attach materials to ensure thermal reliability, necessitating the development of Ag or Cu-based sinterbonding materials as alternatives to conventional solder. Compared to pressure-assisted processes, pressureless processes have significant industrial potential, however issues such as long processing times and low joint density must be addressed. Therefore, this paper reviews previously reported pressureless sinter-bonding methods for Ag and Cu fillers, categorizing them into chemical approaches, particle optimization, and other improvement methods. We analyze and compare the results and characteristics of these studies. The use of Ag nanoparticles in pressureless sinter-bonding has demonstrated rapid joint strength and dense joint formation based on accumulated research, suggesting high potential for future mass production applications. On the other hand, Cu-based pressureless sinter-bonding is still in its early research stages, however recent results showing successful sintering of ultrafine Cu nanoparticles in a nitrogen atmosphere indicate promising progress, suggesting that the development of Cu-based pressureless sinter-bonding technology will continue to advance actively.
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