Common in the high performance power supply market, multilayer IMS PCBs are made from multiple layers of thermally conductive dielectrics. These constructions have one or more layers of circuitry buried in the dielectric with blind vias acting as either thermal vias or signal vias. While more expensive and less efficient at transferring heat as a single layer designs, they provide a simple and effective solution for heat dissipation in more complex designs.

In the most complex constructions a layer of aluminum can form a ‘Core’ of a multilayer thermal construction. The aluminum is pre-drilled and back-filled with dielectric prior to lamination. Thermal materials or sub-assemblies can be laminated to both sides of the aluminum using thermal bonding materials. Once laminated, the completed assembly is thru-drilled similar to a conventional multilayer PCB. The plated through holes pass through the clearances in the aluminum to maintain electrical insulation. Alternatively a Copper core can allow both direct electrical connections as well as with insulated through holes.

Amitron has been producing Aluminum Printed Circuit Boards (also called Metal base PCBs) for over a decade. Although originally envisioned for use in the power-supply industry these substrates are now most widely used in High Brightness LED products.