Oxygen-plasma cleaning of hybrid integrated circuits

The immediate need to eliminate the use of ozone-depleting chlorofluorocarbons (CFCs) is the driving force behind efforts to develop new methods for cleaning hybrid integrated circuits (HICs) without using CFC-113 based solvents. Oxygen-plasma cleaning is a cost-effective method for replacing processes that use these solvents. The performance of oxygen-plasma cleaning has improved over the years, but it has never worked successfully as a method for cleaning high-voltage circuits before they are encapsulated. However, results from a fractional-factorial designed experiment showed that an improved oxygen-plasma cleaning process can achieve cleanliness levels that equal or surpass those using a CFC-113 based solvent. This paper describes how oxygen-plasma substitution for a CFC-113 based solvent was developed and implemented at AT&T's Merrimack Valley Works.