An assessment of the thermal performance of the PBGA family

The plastic Ball Grid Array (PBGA) has generated significant interest as a cost effective packaging alternative for high I/O ULSI devices. This study assesses thermal performance of the PBGA family using the metric of power dissipation capability-"power rating" for IC packages. The metric chosen is the power dissipated for constraints of junction temperature (<105/spl deg/C), and board temperature (<90/spl deg/C), in low aspect ratio enclosures (portable products), as well as natural and forced air convection (/spl sim/1.0 m/s) equipment operating conditions. The free and forced air conditions are typical of PC/workstation environments. Simulation studies using a finite difference based software for thermal performance of IC packages investigated the relative roles of package enhancements towards the thermal performance. Experimental data for the 106 PBGA in free air and portable radio mockup, and the 119 PBGA in free and forced air were used to validate the methodology. The study covers 68 to 324 pincount PBGAs and compares the performance with comparable pincount PQFPs (plastic Quad Flat Package) and other contemporary package styles. The study also addresses system level enhancements for extending the thermal performance of PBGAs for applications. The power dissipation for PBGAs in portable products is projected at 0.6 W. The power dissipation capability of the PBGA is projected to lie in the range 1.5-1.75 W in free and forced air environments. Coupling a motherboard ground plane to the package thermal vias and bumps allows performance enhancement to 2.8 W. A heat-sink attached PBGA allows heat dissipation in excess of 8 W in high end systems. The thermal performance of the PBGA is comparable to PQFP-even when no advantage is taken of the package thermal vias and bumps by the system. Furthermore, the performance of the PBGA compares well with CPGA, CQFP and the CBGA packages.

[1]  H. M. Berg,et al.  Thermal sensitivity analysis for the 119 PBGA-a framework for rapid prototyping , 1995, 1995 Proceedings. 45th Electronic Components and Technology Conference.

[2]  B. Freyman,et al.  Overmolded plastic pad array carriers (OMPAC): a low cost, high interconnect density IC packaging solution for consumer and industrial electronics , 1991, 1991 Proceedings 41st Electronic Components & Technology Conference.

[3]  B. Chambers,et al.  Application of CFD Technology to electronic thermal management , 1994 .

[4]  B. Chambers,et al.  Application of CFD Technology to electronic thermal management , 1994, 1994 Proceedings. 44th Electronic Components and Technology Conference.

[5]  B. Chambers,et al.  Thermal performance limits of the QFP family , 1993, [1993 Proceedings] Ninth Annual IEEE Semiconductor Thermal Measurement and Management Symposium.

[6]  M. Mahalingam,et al.  Surface mount plastic packages-an assessment of their thermal performance , 1989, Fifth Annual IEEE Semiconductor Thermal and Temperature Measurement Symposium.

[7]  J. A. Andrews,et al.  Package thermal resistance model dependency on equipment design , 1988, Fourth Annual IEEE Semiconductor Thermal and Temperature Measurement Symposium.

[8]  J. S. Hunter,et al.  Statistics for Experimenters: An Introduction to Design, Data Analysis, and Model Building. , 1979 .

[9]  Ephraim M Sparrow,et al.  Local and average natural convection Nusselt numbers for a uniformly heated, shrouded or unshrouded horizontal plate , 1986 .