The Study of Glass Core Substrates Warpage

Glass Core Substrates (GCS) is crucial in addressing the challenges of high-density IC package with its good thermal performance and rigidity advantages over traditional Organic Core Substrates (OCS). Even though low-coefficient-of-thermal-expansion (CTE) organic core have been developed to reduce the warpage during assembly, glass substrates offer added benefits of much higher modulus and thermo-mechanical stability, with the potential to reduce warpage beyond low-CTE organic materials. However, these same properties introduce new challenges, such as warpage control during manufacturing and operation. This paper is focus on measurements to quantify the warpage of glass and organic substrates at 400μm core thickness. In the experiments, four-metal-layer substrates were fabricated at the panel level, diced into 37.5×37.5mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> coupons, and the warpage of the assembled substrate was measured using shadow moire interferometry. Glass core substrate (GCS) was demonstrated to have lower substrate warpage than organic core substrate (OCS).