THERMAL-CHARACTERISTICS OF SINGLE AND MULTILAYER HIGH-PERFORMANCE PQFP PACKAGES

In order to meet the electrical and thermal performance requirements of today's high performance devices, an enhanced design of plastic quad flat pack (PQFP) was introduced recently [1]. In this design, the conventional single layer lead frame has been replaced with a multilayer lead frame design. This change is only internal to the package and the package exterior design is intact. By addition of two copper layers to the lead frame, which serve as power and ground planes, not only the package electrical performance is improved, the thermal resistance is also reduced by the heat spreading action of the planes. In this paper, attention is focused on the thermal performance of the single and multilayer PQFP packages. Using experimental and computational techniques, it is shown that significant reduction in the package thermal resistance can be achieved by using a multilayer lead frame structure for medium and high lead count PQFP packages. © 1990 IEEE