IMS - Printed Circuit Boards
IMS boards (insulated metallic substrate) are made of a metallic base material, usually aluminum or copper and a thin insulator layer (prepreg) with high thermal conductivity which carrying the copperlayer of the conductor tracks. They are used when a lot of heat, as occurs for example in high-power LEDs or in Power-MOFETs, to be discharged perpendicular to the circuit board in a rear heatsink. A key criterion in selecting suitable material for a specific application, besides thermal stability, thickness of the copperlayer and thickness of the prepreg, is the thermal conductivity of the prepreg as well as its capability to withstand the applied voltage.
The photo above shows a detail of a circuit board for use with high-power LEDs for industrial application (customer logo on the single PCB defaced). Evident is a register hole (top left), 10 single PCBs (12x20mm) with mounting holes, the tracks with the "Hot Air Leveling" - method (HAL) unleaded pre-tinned solder pads, the green soldermask, my customer-ID, the PCB-ID, and the yellowish-green insulating layer (prepreg) between copper and the non-visible aluminum carrier. The individual printed circuit boards can be separated after assembly by simply breaking along the scored lines of weakness. The material has, besides an excellent thermal stability, a thermal conductivity of 3W/mK and is significantly better than conventional materials with typical 1.6 W/mK.
The photo below shows an unassembled IMS-PCB made of the same high quality material which is in use for the new interior lighting modul (Energy Saving LED-Modul for Indoor Use).