Active Metal Brazed Cu-Si3N4 Composites for Power Electronics

Using Active Metal Brazing (AMB) processes to join Copper to Si3N4 instead of Direct Copper Bonding (DCB) extends the lifetime of circuit boards (AMB-substrates) for power electronics by improved active and passive thermal cycling stabilities. A critical component for the lifetime of AMB-substrates is the fraction of silver in the active filler metals due to silver migration and short cutting of the copper-pads. A silver-free brazing process for Copper-Si3N4 AMB-substrates is presented to elongate the lifetime especially at high voltages. Peel strength and microstructure of the joining interface of silver-based and silverfree active filler metals are compared.