Embedded Active Packaging Technology for High-Pin-Count LSI With Cu Plate

We have developed a thin, reliable, low-thermal-resistance LSI packaging technology by embedding a high-pin-count LSI chip into 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 of only 34 μm at room temperature for 27 × 27 mm
²
in size. It is also possible to reduce the total package thickness to 0.46 mm by etching the Cu plate to half thickness, with keeping the warpage increase up to 117 μm. Low thermal resistance of 10.8°C/W is achieved for the packages with 0.5-mm-thick Cu plate at a wind velocity of 0 m/s, which is almost comparable to that of an FCBGA with a large heat sink. We have successfully demonstrated the functions of our packages using an LSI tester and personal-computer-like system board. They have also passed a 1000-cycle package-level thermal cycle test.