Thin Substrates Bursting into the Market

摘要

The continued drive for miniaturization by mobile applications demands its toll also from packaging. Innovativepackages are required to shrink volume and weight of packages. This has led to the development of single layer,coreless and embedded component substrates. The thinnest prepreg based substrate and concomitant package is asingle layer substrate termed a-S~3 ? and can be as thin as 90 μ and 400 μ, respectively, with the appropriate moldcap. The manufacturing concept for a-S~3 has inspired a new manufacturing concept for thin prepreg based corelesssubstrates with any number of layers. Layers two through seven have been demonstrated successfully. Thepractical layer count is limited only by yield and cycle time. The same concept has been extended also toembedding active die as well as passives, a-EASI?. The total package height here is governed by the thickness ofthe embedded elements. The simplest embedded substrate is a two layer substrate with a MOSFET die. Theadvantage is a very low profile power package with excellent electrical and thermal performance. Theinterconnections to the die/passives are formed by plated laser vias as is a common practice. Process flows andconcepts will be introduced here. Thin substrates do pose many challenges during substrate manufacturing as wellas during assembly. Some of the handling concepts will be elucidated. Sample pictures will be shown todemonstrate successful builds and some reliability data will be presented as well.