Investigation of Post-Etch Copper Residue on Direct Bonded Copper (DBC) Substrates

Abstract

For many years, direct bonded copper (DBC) substrates have proved to be an excellent solution for electrical isolation and thermal management of highpower semiconductor modules. However, in this study we detected a copper residue on the surface of DBC alumina, presumably a result of pattern etching even in industry. As is known, growth of metal dendrites could be observed with the assistance of electric field, temperature, and humidity. Metal dendrites normally grow from the cathode to anode. Silver and copper are two kinds of metals susceptible to migration. In this work, copper dendrites could be formed at 400°C and 50 V/mm between conductors. These dendrites may impact the reliability of DBC in power electronic applications. Therefore, the formation of copper residue is an interesting phenomenon for etched DBC and warrants further attention in the future.

Thermal shock reliability of a GaN die-attach module on DBA substrate with Ti/Ag metallization by using micron/submicron Ag sinter paste

“…18) However, in spite of these excellent performances, some of the previous studies have reported that DBC showed an unreliable performance due to the oxidation and diffusion of copper through the grain boundary in a high temperature environment (<250 °C). [19][20][21][22][23][24][25] In our previous study, a Ni barrier layer showed poor inhibition of Cu diffusion in hightemperature die-attach applications, but a Ti barrier layer deposited on the DBC surface helped to prevent Cu diffusion into the Ag and consequent Cu oxidation. 25) The traditional 5000 nm Ni-metallized DBC substrates are no longer stable at high temperatures of 250 °C.…”

Perspective Method for Regeneration of Spent Solutions from Printed Circuit Boards Etching

“…Sulfur/chromic acid can release large volumes of hazardous substances. Waste ferric chloride solution [3][4][5] is difficult to treat and hard to reuse. Cupric chloride [6,7] includes two types of acidic and alkaline and is the most widely used at present because of its easy regeneration capability and low waste production.…”