CPS Offers AlSiC Metal Matrix Composite Base Plates For IGBT Modules

CPS Corp. announced that it is offering AlSiC (Aluminum Silicon Carbide), a metal matrix composite well suited for base plates material for insulated gate bipolar transistor (IGBT) used in high-power traction, power control, Hybrid Electric Vehicle power systems, and fly-by-wire applications. AlSiC has been tested and is RoHS compliant.

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 applications. The AlSiC CTE match reduces the mechanical stresses on IGBT die and substrates that is induced by thermal power cycling, which is said to improve the reliability of the substrate attachment and to reduce die cracking failures.

The device compatible AlSiC CTE is said to eliminate the need for stress compensation material layers that are required in Cu (CTE = 17ppm/°C) baseplate assemblies. It is claimed that the 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 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 a suiatble cooler material for the weight-sensitive IGBT applications. AlSiC is also said to have higher strength and stiffness than Cu, which, combined with its lightweight nature, is to make 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 x 140mm, 140 x 130mm and 140 x 70mm base plate formats (shown) as well as custom formats.