A novel ultra-thin package for embedded high-pin-count LSI supported by Cu plate

We have developed a thin, low-thermal-resistance LSI package by embedding a high-pin-count LSI chip into ultra-thin build-up layers supported by Cu plate. The embedded LSI chip is a microprocessor with approximately 1500 pads and a thickness of 50 µm, and it is completely laminated by the first build-up epoxy resin. The total package thickness is only 0.71 mm including a 0.5-mm-thick Cu plate for cooling, which is much thinner than the conventional flip chip ball grid array (FCBGA) package with a heat sink. Our package shows excellent warpage characteristics, smaller than 82 µm in the temperature range from −55 to +260 °C. Low thermal resistance of 10.8 °C/W is achieved at a wind velocity of 0 m/s, which is also comparable to that of the FCBGA with a large heat sink. We have successfully demonstrated the functions of this package using an LSI tester and personal-computer-like system board. It has also passed a 600-cycle package-level thermal cycle test.