The effect of internal package delaminations on the thermal performance of PQFP, thermally enhanced PQFP, LOC, and BGA packages

Plastic IC packages rely on a contiguous structure for efficient heat conduction from the chip to the surrounding environment. Any discontinuity within the package, such as an interfacial separation or delamination, degrades the thermal efficiency of the package. Four package types have been studied with respect to the thermal impact of interfacial delaminations; a 240 pin plastic Quad-Flat-Pack (PQFP), a thermally enhanced 240 PQFP, a 28 pin Lead-on-Chip (LOC) package, and a plastic overmolded 388 Ball-Grid-Array (PBGA) package. Modeling found wide variation in the sensitivity of the package to thermal degradation based on package type and delamination location. The largest shifts (50%) were found in thermally enhanced packages. The results identify interfaces critical to thermal integrity. In addition to studying the thermal impact of delaminations, practices to thermally enhance the PBGA package will be discussed.