Investigation on decap shift and incomplete fill issues in the wafer level compression molding process

Decaps are the panacea to cure the noise related issues. Due to the short distance advantage, decaps were embedded in the package instead of PCB. These decaps, generally having higher thickness than chips, would play a vital role in the wafer level molding process. Improper population will cause decap shift and incomplete fill issues. In the present paper, proper arrangement of decaps were designed and optimized. The results show that decaps placed along two adjacent sides rather than two opposite sides of the chip would result in better filling. In order to further reduce the drag force on decaps, chip to decap distance should be as large as possible. This implies that narrow gaps would result in higher drag force. Therefore, narrow gaps should be avoided to ease the drag force in the package as well as the whole wafer.