DocumentCode :
427418
Title :
A numerical study of the effects of temperature, moisture and vapour pressure on delamination in a PQFP during solder reflow
Author :
Guojun, Hu ; Tay, Andrew A O
Author_Institution :
Dept. of Mech. Eng., Singapore Nat. Univ., Singapore
fYear :
2004
fDate :
8-10 Dec. 2004
Firstpage :
98
Lastpage :
104
Abstract :
Delamination during solder reflow is a critical reliability problem for the plastic IC packages. The main objective of this paper is to investigate the effects of temperature, moisture diffusion and vapour pressure on the likelihood of delamination of the interface between the leadframe pad and the encapsulant. In this paper the entire thermal and moisture history of a plastic IC package is simulated from the start of level 1 moisture preconditioning (85°C/85%RH for 168 hours) to subsequent exposure to a solder reflow process lasting about 5 minutes. The transient development of the strain energy release rate due to thermal stress only Gt, hygrostress only Gh, vapour pressure Gp and combined Gtot are computed and studied by using a new modified crack surface displacement extrapolation method (MCSDEM). Finite element models were constructed for a 160-leaded PQFP. The initial crack length was varied from 0.1mm to 3.5mm in order to study its effect. The results show that for small cracks, the effects of temperature and moisture are dominant while that of vapour pressure is insignificant. For moderate crack lengths, the effect of temperature is greatest. For large crack lengths, the effect of vapour pressure is dominant.
Keywords :
delamination; extrapolation; finite element analysis; heat transfer; integrated circuit packaging; interface phenomena; moisture; reflow soldering; stress analysis; surface cracks; vapour pressure; 185 C; 604800 s; PQFP delamination; encapsulant; finite element model; hygrostress; leadframe pad; level 1 moisture preconditioning; modified crack surface displacement extrapolation method; moisture diffusion; plastic IC package; solder reflow process; strain energy release rate; temperature effects; thermal stress; vapour pressure; Capacitive sensors; Delamination; History; Integrated circuit modeling; Lead; Moisture; Plastic integrated circuit packaging; Surface cracks; Temperature; Thermal stresses;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Electronics Packaging Technology Conference, 2004. EPTC 2004. Proceedings of 6th
Print_ISBN :
0-7803-8821-6
Type :
conf
DOI :
10.1109/EPTC.2004.1396585
Filename :
1396585
Link To Document :
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