The above picture shows the B/C/B film between 2 glass slides before pressure and heat are applied. The unique B-Stage diamond pattern is pronounced and designed to allow air to escape from between substrates upon applied pressure during heat cure.
The above photo depicts “squished” B/C/B film that has been cured under heat and pressure. The diamond pattern melts and cures to a thin, uniform, void-free adhesive layer.
B/C/B is Aptek’s trademark for unique film adhesives that go against conventional wisdom that uses glass-fabric as the carrier system. Instead, Aptek uses a low modulus, C-staged resin matrix as the carrier for the B-staged resin applied to each side of it. When this product is fully cured, it becomes a low-modulus, stress absorbing adhesive and is quite effective in large area bonding of ceramics to metal. The B/C/B system is designed to manage stresses developed from CTE mismatches during temperature cycling as well as to dissipate heat generated from components and circuitry.