High via density thin metal-core PCB using electro-coated dielectric

Abstract

Conventional printed circuit boards (PCBs) may be replaced by thinner metalcore boards for some applications, as well as for package substrates. Using thin, metalcore technology may provide advantages for radio frequency (RF) circuits and packages, and increase heat dissipation for high power applications. The metalcore technology has several layers including the metal core, electrocoated dielectric, sputtered metal layers, and electroplated copper. Especially for RF application and automotive electronics printed circuit boards with a metal core is gaining interest. The advantage of metal core PCB is the low thermal coefficient as well as the possibility to achieve a high density of vias and electronic component assembly. This paper describes the realization of metal core PCB with a dense array of vias and with a low thermal coefficient. The dielectric layer is applied after vias have been formed providing a high density electronics assembly on a double sided PCB which exhibits the heat dissipation of a metal core with minimal thermal expansion. After photochemically etching an array of vias, the metal core can be optionally plated with copper. The insulating dielectric is applied using a highly reliable electrodeposited coating. Metal core substrate provides the opportunity to form a via to the metal core to provide electrical grounding. The final traces are fabricated on top and bottom and can be interconnected through via openings.