Cleaning IGBT modules, i.e. DCBs, is an absolute must within the power electronics industry. The substrate surfaces must be prepared for wire bonding after the die attach process. Cleaning is also necessary after the "heat sink soldering" process and before modules are further processed, that is molded, wire bonded and/or connected to the frames. There are two main requirements for the cleaning process:
- Complete removal of contaminants that typically remain on substrate surfaces, and chips. Residues can impair achievable shear values for copper and IGBTs.
- Visually spot-free substrate and chip surfaces such that it is able to activate oxidized surfaces.
Using specifically developed processes with aqueous-based ZESTRON cleaning agents, clean surfaces can be achieved that will significantly increase the wire bond quality. Consequently, shear tests results as well as the qualification through power cycling (long-term reliability) test will be significantly improved. This also increases the product yield.
Using modern water-based cleaning processes provide optimal compatibility with various chip passivation and substrate surfaces. Eliminating the need for subsequent plasma treatments that are typically necessary, unsuitable cleaning agents attack the passivation leading to impairment of chip function.