Recovery Cleaning – Restoring Solderability using Plasma

We are always looking for ways to expand our core service offerings to meet the challenging and ever-changing needs of our clients. One example is our use of a plasma cleaning system to restore solderability to electronics assemblies and components.

We use a Yield Engineering YES-G1000 plasma cleaning system to remove surface organic residues and oxides. Oxygen plasma is used to improve surface adhesion by removing low molecular weight atoms (e.g. carbon, oxygen, hydrogen) and activating the surface. This can leave behind a clean surface with copious bond points for an adhesive or other material to utilize. Also, use of oxygen combined with inert gas(es) can remove organic residue as well as oxides from a metal surface to improve metal-to-metal adhesion (e.g. soldering, ball-bonding). 

Case 1 – Restoring Solderability of PCBs

A client contacted us regarding flight hardware that had been stored for over a year and had oxidized and become non-solderable. The PCBs were processed in the plasma cleaning system for three minutes utilizing a custom plasma-gas composition. After cleaning, the boards were verified to meet or exceed IPC solderability standards.

Case 2 – Restoring Solderability of Components

Another client submitted surface mount components packaged on tape and reel that were found to be non-solderable. The components were left in the tape and processed in the plasma cleaning system for two 3-minute cycles with a custom plasma-gas composition. Samples were subjected to a reflow profile after cleaning to verify solderability was restored.

Plasma cleaning offers a variety of advantages:

• Short cycle times

• Versatility (i.e. process chemistry, pressure, RF power, run time that can be tailored to the project)

• Minimal environmental concerns (i.e. no hazardous wastes or EH&S concerns)