FR-4: the default
Woven glass fabric in an epoxy resin, clad with copper. It is mechanically strong, available in thicknesses from 0.1 mm to 6.0 mm, and supports the full multilayer range we build, up to 38 layers. If a design has no unusual thermal or RF requirement, FR-4 is almost always the cheapest route to a working board.
Metal core: move heat, not signals
The circuit layer sits on a thin dielectric bonded to an aluminium base. Heat leaves through the metal, which is why LED arrays and power stages use it. The trade-off is density: the thin dielectric and conductive base make plated through holes and multiple signal layers impractical, so metal-core boards are usually single or double sided.
Ceramic: dielectric stability at temperature
Alumina and aluminium nitride substrates hold their electrical properties at temperatures where FR-4 would degrade, and they conduct heat far better than epoxy laminates. They are used in power modules, RF front ends and sensors, and they are normally built as single or double-sided circuits with laser-machined features.
How we choose
We start from three questions: how much heat must leave through the board, how stable must the dielectric be, and how much routing density is needed. The answers pick the family; the stackup and copper weight follow from the electrical and thermal model.
