A THERMALLY ENHANCED BALL GRID ARRAY PACKAGE

摘要

Overmolded plastic ball grid array package has several advantages over fine-pitch plastic quad flat package, such as smaller footprint, better electrical and thermal performance, superior surface-mountability, etc. Several types of ball grid array packages show better thermal management capability than the overmolded plastic ball grid array packages. Among them are the plastic ball grid array package with cavity-down structure, and the ceramic ball grid array package. However, they are fairly expensive to fabricate. Therefore, a ball grid array package with new configuration was developed to get the improved thermal performance at relatively low assembly cost.rnThe new ball grid array package, "Metal-lid Ball Grid Array Package", has been developed, in this design, the heat from the chip was conducted to metal-lid through thermally conductive materials such as metal ribbons and thermal silicone. There was no transfermolding process in the assembly of this package. Instead, the substrate, on which an integrated circuit chip was electrically interconnected, was sealed with a metal-lid using adhesives. Except the metal-lid sealing process, the assembly processes of the metal-lid ball grid array package were the same as those of overmolded plastic ball grid array package.rnThe thermal performance of metal-lid ball grid array package was evaluated and compared with that of the plastic ball grid array package. The metal-lid ball grid array package showed the improvement of thermal performance by 27% over the plastic ball grid array package with the same substrate size and the same number of I/O's. Pre-conditioning tests were also carried out to compare the reliability between two types of packages.