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|Molding Compound and Substrate Core Material for Thin Package|
|Keywords: Molded Underfill, PoP, Low CTE Core|
|According as the advance of mobile device and package, epoxy molding compound(EMC) and substrate are facing difficult technical requirement from assembling industry. Thin package which is one of the big trend of packaging technology needs new material for low warpage and good mold ability. EMC for thin mold package like as PoP was developed by new filler and resin system etc. several years ago and applied widely for PoP bottom an top package, but now is facing uncontrollability of warpage by EMC with some very thin mold package for example 0.15mm thickness. New technical concept besides mold shrinkage rate was studied and it found that other physical and thermal property showed some effect for decreasing warpage of very thin mold. On the other hand, many flip chip have been applied to mobile device, and new underfill process so-called molded underfill has been applied for lower process cost and higher reliability. EMC for molded underfill was developed by the fine filler with high flow ability technology, and by the control of cure property and reducing surface tension between die and substrate for goof filling under die. Also high adhesion and low stress technology was developed for Cu pillar. Regarding a core material for a substrate, thickness requirement is getting thinner and thinner because of higher density. Stiffness requirement is higher than previous materials because of reducing semiconductor substrate warpage. Today's finer flip chip has narrow pitch and small solder ball, and when that FC is mounted to very thin substrate, interconnection reliability will be low by big warpage of substrate. We have studied the factors of substrate warpage, and different level of CTE(x and y direction) material and different level of elastic modulus material at 260 degree C were evaluated as substrate. Lower CTE(x and Y direction) and higher elastic modulus at 260 degree C material will help to reduce warpage. Also that approach technique will affect drilling process.|
|Masashi Nakamura, General Manager
Panasonic Electric Works Co., Ltd.
Kadoma, Osaka 571-8686,