During the packaging process of power modules, organic substances such as oil stains and grease, as well as oxide layers, will inevitably adhere to the surfaces of DBC substrates and chips. Prior to packaging, these surface organics and oxide layers must first be removed. A plasma cleaner is a high-precision dry cleaning device. Its working principle is that under the excitation of radio frequency (RF) voltage, activated gas generates plasma, which drifts on the surface of the objects to be cleaned and decomposes and removes surface impurities through physical collision and chemical reaction.

Functions of plasma cleaning in power module packaging

Plasma cleaning of substrates and connecting components prior to nano-silver sintering can improve the hydrophilicity of substrates, enhance the wettability and spreadability of subsequent nano-silver paste printing, thereby boosting the sintering quality.

The copper layer on the surface of DBC is prone to oxidation upon contact with air, which seriously impairs the wire bonding quality and chip soldering effect. Plasma cleaning of DBC can remove the oxide layer on the copper surface, thus improving the wire bonding strength and increasing the soldering yield rate.

Workflow of the Inline Five-lane plasma cleaner

The first transfer station conveys materials to the code reading unit. After code scanning via the code reader, the first transfer station continues transporting the materials to the second transfer station. Once all five materials are transferred to the second transfer station, it sends them into the vacuum plasma cleaning chamber. Plasma is then used to decontaminate and modify the material surfaces. After cleaning, the materials are further conveyed by the second transfer station to the third transfer station, which delivers the cleaned materials to the next processing station. Through the integrated configuration of its vacuum plasma cleaning unit, material transfer unit, code reading unit and buffer unit, this equipment realizes integrated and fully automated cleaning of DBC substrates for power modules, which improves operational efficiency and reduces labor costs.