Memory Module With Polyimide Alpha Barrier
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
A polyimide layer is used as an alpha barrier in a memory module. Alpha particle emission from ceramic substrates can cause faulty operation of the memory circuit chip(s) mounted to the substrates. It is customary in conventional memory modules to provide an alpha barrier layer after chip mounting that covers the exposed ceramic substrate's circuitized surface surrounding the chip(s) C-4 (controlled chip collapse connection) joints to minimize the emission effects. However, because of the plastic nature of the type barrier used, the barrier often seeps between the surface-mounted chip and substrate creating stresses during subsequent processing that cause failure of the solder bond between the chip and substrate pads.