A smaller, lighter power supply will have an immediate market in both the commercial and military sectors. Higher switching frequencies reduce the size of power supplies but existing transformer core materials are forced to operate at low frequency to avoid losses in the transformer core. This proposal identifies a microengineering approach to form a new core material which eliminates these losses by making a laminated magnetic structure with both the magnetic and insulating strips formed by thin film deposition techniques, allowing the structure to be "microengineered" with specific properties not available by conventional fabrication techniques. The Phase 1 program will fabricate a transformer which can produce a power supply of unequaled size and performance. Use of a thin film magnetic material in combination with thin film windings on a thin flexible substrate will result in a totally integrated, low profile, highly efficient planar power supply.