Project Title:

Liquid Crystal Polymers for CTE Matched PWBs

04.11-3200
902075
Liquid Crystal Polymers for CTE Matched PWBs

Abstract:

This project addresses the use of liquid crystal polymer (LCP) materials and processes
to fabricate laminated printed circuit boards (PCB) with the in-plane coefficient
of thermal expansion (CTE) matched to the ceramic chip carriers (6 to 7 ppm/oC) and
the out-of-plane CTE below 30 ppm/oC. This approach will solve the problem of thermal
fatigue related failures of solder joints enabling the implementation of surface
mount technology in space flight electronics. Also, this approach will enable the
use of reliable multilayer circuits by minimizing thermally induced stresses on plated,
through-hole vias. The result will be performance gains (weight and volume reductions
over 50 percent below current designs), clock speed and memory size increases, along
with reliability for long duration (up to 20 year) missions. In Phase I, a unique
film extrusion process followed by novel post processing techniques to tailor the
CTE of the LCP circuit layers will be used to  demonstrate that innovative materials
and processes can eliminate the problem of thermal fatigue in solder joints. In Phase
II, techniques will be developed for fabricating multilayer boards with LCPs. The
solder joint's performance and reliability advantages and commercial viability of
these new materials over the current state-of-the-art will be demonstrated.
Controlled CTE, multilayer PCBs will permit NASA's future space programs (such as
the Advanced Tracking and Data Relay Satellite System to utilize the increased speed,
smaller size, lighter weight, and larger memory offered by today's leadless ceramic
chip carriers and surface mount technology.
CTE matched boards, laminated printed circuit boards, liquid crystal polymers, solder
joint reliability, spacecraft electronics, electronics packaging