Development of Multi Chip Module BGA Package for High Power Application
The relentless trend of ever increasing functionality integration and die shrinkage for cost reduction and miniaturization of products have led to intense heat dissipation in IC chips. To provide sufficient cooling of such devices at acceptable cost is becoming a challenging task for component as well as system engineers. Since the introduction of the standard Ball Grid Array (BGA) package, continued efforts by package developers have successively resulted in a family of thermally enhanced BGA packages, among which HS-PBGA (Heat Slug Plastic Ball Grid Array) is the most common package available in the market. While being a low cost solution, it is only applicable to those relatively bigger packages where space is not a concern. For chip-scale package (CSP) where the chip is occupying most of the area of the package, or System-in-Package (SiP) where multiple dice and passive devices may present, this solution is extremely difficult, if not impossible, to implement.UTAC has successfully developed a simple alternative thermal enhancement technology, which overcomes those problems inherent to HS-PBGA. It involves attaching a flat heat-spreader onto a molded BGA package with the option of adding a dummy silicon die to the top of the active die for applications where there is an external heat sink. This XP (eXtra Performance) concept to boost thermal performance of BGA package seems to be very promising since it uses standard assembly process flow, hence a low cost solution for high power application.In the case of recent application to 832B FBGA 31x31, it has proved again to be an effective tool for promoting heat dissipation in multi chip module (MCM). Simulation shows that the thermal resistance of XP-FBGA 31 x31 MCM (Fig. 1)can be reduced by 44％ against that with standard packaging technique under natural convection.The XP-BGA package consists of different materials and structures and package warpage is a concern as it manifests ball co-planarity failure at final inspection. In early development phase, however, it would be very costly and time consuming to build package to assess the impact of various parameters on thermal resistance and package warpage.Aiming to minimize prototype revisions and reduce overall turnaround time from design, to prototype, to high volume assembly production, this paper describes approaches of the design optimization for XP-BGA through mechanical and thermal modeling on designed experimental legs. 3D CFD (Flotherm) and FEM (Ansys) analysis tools were used for sensitivity study of such variables as dummy die and copper lid, TIM (Thermal Interface Material) BLT (Bond Line Thickness), mold flash over dummy die, and TIM coverage.The predicted values were then compared with the measurements from the actual built samples to certify the.creditability of the model. In addition, the pilot build underwent moisture sensitivity test at MSL 4 @260C followed by 300X Temperature Cycling to assess the material suitability. Result shows that the predicted and actual measurement for thermal performance and mechanical warpage was less than 5％, and 45％ respectively in terms of error range.
Y.Y.Ma
Packaging Analysis and Design Center, United Test and Assembly Center Ltd, 5th Serangoon North Ave 5, 554916, Singapore
国际会议
第八届电子封装技术国际会议(2007 8th International Conference on Electronics Packaging Technology ICEPT2007)
上海
英文
138-139
2007-08-14（万方平台首次上网日期，不代表论文的发表时间）