Understanding the use of low coefficient of both hygroscopic and thermal expansion polymer matrix for the inner substrate multichip packages with multilevel interconnection

The development of a multimodule package based on an organic substrate adhering to a lead frame is described. This substrate has a small coefficient of both hygroscopic and temperature expansion, which keeps the lead-frame warping to a minimum amount. Several types of wire-bonding methods can be used. As the sealing material adhered to a metallic lead frame, this substrate has shown excellent adhesion both to a transfer-molding resin and a lead frame so that inner conductors are more stably leaded out. Without metallic lead frames and with the aid of top-hat coat resin, it has improved thermal and hygroscopic coefficients. The top-hat resin and soldering resist are also furnished by an aromatic epoxy, making reflow soldering of passive components possible after semiconductor-chip mounting