There are different methods of aluminum usage in PCB manufacturing industry. Mostly the aluminum PCBs are used for LED lighting applications. There technical name is Insulated Metal Substrate or IMS PCBs. The aluminum here is used as the carrier of the copper and heat sink applications. For examples this type of PCB are used for high power LED (1W, 3W, 5W etc.,) applications, control system parts, motor control, power conversion, power transduces and power delivery systems etc. Nowadays these types of PCBs are replacing the FR-4 PCBs in domestic lighting applications. The basic construction structure of an IMS PCB includes:: the aluminum foil material is placed at the bottom, then the composite resin material which is electrically insulator but thermally onductive, finally at the top the copper foil or laminate and then pressed under high pressure and temperature. The basic structure of an IMS PCB is shown in figure 1. Common PCB thickness is 1.6mm, 100µm ceramic isolation layers and 35µm copper foil over the insulation layer. The tracks are made over the copper laminate layer. Components are also placed and soldered on the copper layer side.
Fig. 1:- Basic structure of IMS (Aluminum) PCB
Fig. 2:- A high power LED mounted over an IMS PCB
Another form of aluminum PCBs is thick/ thin film ceramics-aluminum PCB which is a modified type of IMS. The conductor is applied over the core material i.e., ceramic material whereas the aluminum oxide or aluminum nitride are used as the base material that dissipates heat sufficiently. The thermal conductively of aluminum oxides is also very better.
Fig. 3:- Small power LED PCB assembled for lighting applications
Moreover, as compared to the FR-4 , FR-5 or CEM-1/2 material, aluminum PCBs have various advantages over the described PCBs. The Aluminum is a low cost metal and easily available. Its processing cost is also low. Their final products are low priced. The Aluminum PCBs are environment friendly, excellent heat dissipater, more durable and light weight. By mechanical point of view they are more rigid and reliable, increase product life and durability. By electrical point of view they are excellent in EMC-EMI shielding characteristics.