Low CTE Cast-Polyimide Substrate for Tape Packages Applications

摘要

This paper will discuss a new low CTE cast polyimide substrate (Espanex-KB/KC) for tape carrier packages. This new TBGA substrate is based upon a flexible polyimide dielectric with low CTE properties, reduced moisture absorption and a low dielectric constant. The enhanced properties of Espanex-KB plus thin, low profile Electro Deposited Copper provides designers with fine pitch imaging capabilities, improved electrical performance and thermal peel strength stability after exposure at 150℃ for 1000 hours. Also, Espanex-KB can meet JEDEC level 2 soaking condition of 168 hours followed by IR reflow at 260℃. Micro-Via processing of Espanex-KB was evaluated using CO_2 pulse laser with a conformal mask. Data indicates good via formation and ablation speeds.