polyamide laminates pcb
I have used metal and ceramic pcb designs. The metal base is aliminium or copper or an alloy and the tracks are normally on one side. They are used for efficient heatsinking of IGBT and Mosfets in D2 type packages in high power applications like fork lift truck motor drives, welding equipment and such like. They are impossible to rework if a component is faulty unless you have specialist tools. You cant get enough local heat to melt the solder!