Layered Construction
Copper cladding processes create a thick metal layer fused to a ceramic base to provide both electrical connectivity and heat dissipation. The direct bonded copper process relies on a controlled oxidation of the metal surface to create a eutectic liquid at the interface. This liquid wets the ceramic and forms a strong bond upon cooling.
Adhesion Mechanism
Temperatures during the bonding cycle typically exceed 1065 degrees Celsius in a nitrogen atmosphere with precise oxygen levels. Because direct bonded copper creates a chemical union that surpasses the strength of a mechanical grip, the resulting laminate offers high peel strength and excellent thermal contact. The thickness of the copper can range from 125 to several hundred micrometers depending on the current requirements.
Power Handling
Large cross sectional areas in the traces allow for high current densities with minimal resistive heating. In modules where rapid switching occurs, direct bonded copper provides the necessary thermal mass to absorb transient heat spikes. The ceramic core maintains high dielectric isolation between the circuit and the base plate.
Thermal Pathway
Heat moves directly from the semiconductor through the solder and into the copper layer before spreading into the ceramic. Reliability is measured through the number of thermal cycles the bond can survive before voids appear.
