Reliability with Smart Composite Products


CPS Offers AlSiC Metal Matrix Composite Base Plates for High Power and High Reliability Motor Control IGBT Power Modules

AlSiC-9 base plates for IGBT Power Modules offer high reliability for extended service life ... helping to reduce the cost of energy over time

AlSIC IGBT Baseplates
CPS AlSiC IGBT Baseplates

More than half of the electricity consumed in the word is to drive motors of some kind, whether it is commercial, industrial or military applications. Hence, Motor Control IGBT Power Modules need to meet the energy efficiency and reliability standards for today's variable speed motor control applications. Both factors affect the cost of energy over time. The switching for motor speed controls thermally stresses the IGBT power modules.

CPS Corporation, the worldwide leader in the design and production of metal matrix composites, offers AlSiC (Aluminum Silicon Carbide), a metal matrix composite ideally suited for base plates material for insulated gate bipolar transistor (IGBT) used in high-power traction, power control, and motor controller (motion control) applications.

The low isotropic coefficient of thermal expansion (CTE) value of AlSiC-9 (8 ppm/°C: 30 – 100°C) is compatible with the thermal expansion value of the die or substrate used in IGBT power modules for motor control applications. The AlSiC CTE match reduces the mechanical stresses on IGBT die and substrates that is induced by thermal power cycling (variable speed motors, surges, etc.), which improves reliability of substrate attachment and reduces die cracking failures.

The device compatible AlSiC CTE eliminates the need for stress compensation material layers that are required in Cu (CTE = 17ppm/°C) baseplate assemblies. Elimination of stress compensation materials simplifies assembly and reduces the thermal resistance for AlSiC systems so that AlSiC systems have equal or improved thermal dissipation over Cu baseplate assemblies.

In high power motor control applications (> 1200 V/ 400 A), IGBT modules assembled with AlSiC baseplates are found to have a service reliability of many tens of thousands of thermal power cycles over Cu equivalent systems.

AlSiC is a lightweight material (1/3 that of Cu), which makes it an ideal cooler material for the weight-sensitive IGBT applications (aircraft actuators, control systems, etc.). AlSiC also has higher strength and stiffness than Cu, which, combined with its lightweight nature, makes AlSiC assemblies more tolerant shock and vibration.

The CPS AlSiC near net-shape fabrication process both produces the composite material and fabricates the product geometry, allowing for the design of IGBT base plates with a dome profile. This geometry improves thermal interface contact with cold plates and coolers, adding to AlSiC’s advanced thermal management qualities. CPS fabricates standard of 190 mm x 140 mm, 140 mm x 130 mm and 140 mm x 70 mm base plate formats (shown) as well as custom size configurations. AlSiC has been tested and meets the requirements of the Restriction of Hazardous Substances Directive of the European Parliament (RoHS compliant).