신소재공학과 나노 패키징 및 접속 연구실 (백경욱 교수님)에서 아래와 같이 세미나를 개최하오니 관심있는 분들의 많은 참석 부탁드립니다.
ㅁ 일시 : 2015.03.04 (수) 오후 3시~
ㅁ 장소 : 응용 공학동 1층 신소재공학과 #1317 강의실
ㅁ 연 사 : 한봉태 박사님
( Mechanical Engineering Department, University of Maryland, College Park)
ㅁ 초청교수 : 신소재공학과 백경욱 교수
Moisture Ingress, Behavior and Prediction Inside Semiconductor Packaging
Reliability issues associated with moisture have become increasingly important as advanced electronic
devices are nowhere more evident than in portable electronic products. The transition to the Pb-free
solders, which requires higher reflow temperature, makes the problem further exacerbated. Moisture
absorbed into semiconductor packages can initiate many failure mechanisms, in particular interfacial
delamination, degradation of adhesion strength, etc.
The absorbed moisture can also result in catastrophic crack propagation during reflow process, the well-
known phenomenon called pop-corning. High vapor pressure inside pre-existing voids at material
interfaces is known to be a dominant driving force of this phenomenon. It is also known to cause
interconnection failure in the flip chip package, where delamination initiated from air-trapped cavities
within underfill grows unstably during reflow process. Although there have been numerous researches
on dynamic interactions between the void pressure and the crack propagation, the moisture behavior
inside and around the void is not yet clearly understood, i.e., how water accumulates inside the void.
The first half of this seminar presents a review and a brief quantitative assessment on various existing
mechanisms of water accumulation inside voids at polymer interfaces from the chemical potential point
of view. They include condensation, adsorption, capillary, microfogging, and quick diffusion.
The second half will be devoted to the standard procedures to obtain the critical hygroscopic properties
as well as advanced numerical modeling schemes to analyze the moisture diffusion phenomenon using
the thermal-moisture analogy as well as the mass diffusion.