KALYAN NUKALA -
“pH Neutral and Alkaline Cleaning Agents – Market Expectation & Field Performance”
In recent years, significant changes in solder paste formulations and assembly processes have occurred. Post reflow residues of tin-lead and lead-free soldering materials are more difficult to remove due to increases in component density, larger component packages, higher lead counts, finer lead spacing and lower stand-off heights. While modern aqueous alkaline cleaning agents effectively remove these flux residues, achieving satisfactory results often requires an increase in temperature, exposure time, chemical concentration, and mechanical energy. This presents a new set of challenges in the area of material compatibility. Are pH Neutral cleaning agents a solution?
This presentation details cleanliness test results of a two phase DOE comparing pH Neutral and Alkaline cleaning agents. In Phase 1, the material compatibility effect of the cleaning agents was assessed for exposure under the worst case scenarios with particularly sensitive materials. In Phase 2, cleanliness performance of each cleaning agent was assessed utilizing industry standard and IPC-B-52 tests vehicles populated with numerous low standoff components that have been soldered with commonly used leaded and lead free solder pastes. Cleanliness assessment techniques included surface and under-component visual inspection, SIR and Ion Chromatography analyses.
Finally, a customer case study is presented featuring a Class III OEM, material compatibility challenges faced with their current cleaning process upon implementing a new program and the DOE developed and executed to resolve the issue.