Self-reinforced dielectric substrates based on PIBO film

Consumer electronics products in applications including mobile communications, work stations, small computers, automotive controls, and even high temperature, high reliability but less cost sensitive applications in military, space and aerospace, are moving relentlessly toward smaller, thinner and lighter formats in less costly packages. Interconnect (attachment pad) density requirements in these products are rapidly outstripping the density achievable through fabrication of traditional multilayer printed wiring boards (PWBs) derived from currently available materials. Reinforced dielectric substrates for PWBs (whether woven or non-woven and regardless of resin Tg) are reaching limits of utility for state of the art electronics. Build-up of dielectric layers on traditional PWBs utilizing photo, laser or plasma formed mass vias with small pads is one of the few approaches capable of achieving the desired functionality of leading edge products, even though a substantial cost penalty is incurred. A second way to increase routing density by creation of smaller pads is through the use of new cost effective dimensionally stable laminates. Dielectric film substrates which are thin, self-reinforced and have a high degree of in-plane isotropic dimensional stability are in development. These materials could provide for small vias and capture pads while utilizing the economics of large panel (18" by 24") fabrication. Copper clad panels and associated bond-ply adhesives based on polyimidebenzoxazole (PIBO) film will provide that capability.