Application of embedding insulation sheet (EBIS) for FOWLP

Fan-out wafer level package (FOWLP), which is effective for thinner, lower-cost package and higher I/O, is attracting attention in accordance with the development and spread of smart phone and tablet PC. FOWLP is molded by liquid molding material using compression molding process. However, the liquid molding material has become difficult to respond to the increasing needs of large panels for cost reduction. Nowadays, the insulation material of sheet form which is capable of large size molding is attracting a lot of attention. Therefore, we have developed embedding insulation sheet (EBIS) which is capable of molding large size FOWLP. EBIS has the advantageous effect to reduce the flow distance for filling the spaces of different height and gap, compared with liquid and granular materials. EBIS is also excellent in terms of workability. In this study, we investigated the applicability of EBIS to the assembling of FOWLP. We have conducted a series of assembly process of temporary Si die bonding, compression molding, formation of photosensitive insulation material, Cu patterning by semi-additive process and solder ball mounting. Then, we have evaluated the package level warpage and reliabilities. We also conducted the adhesion and reliability tests of EBIS in combination with photosensitive insulation material (HD-8940), and found that it has the excellent adhesion and reliability of 500 h pressure cooker test.