Co-solvent cleaning ups PCB quality

A Kerry Ultrasonics co-solvent cleaning system has upped cleaning quality and reduced reject rates for Electronic Technicians, which assembles printed circuit boards for aerospace industries.

Electronic Technicians Limited (ETL), which assembles printed circuit boards for the aerospace and general electronics industries, has seen an improvement in cleaning quality and a reduction in reject rates after the installation of a co-solvent cleaning system from Kerry Ultrasonics.

The Microsolve 350 replaces a system that ran on 141B, a solvent due to be phased out from January 2002.

The new machine uses an environmentally friendly, specially blended mixture of 3M's Novec HFE 71 IPA and a hydrocarbon solvating agent.

While its forerunner required topping-up on a daily basis, the Microsolve 350 needs only a single weekly replenishment.

Populated boards undergo a two-stage cleaning process, followed by rinses in pure hydrofluoroether (HFE) and HFE vapour.

The drying stage leaves them clean to military specification, ready for packaging.

"Our previous cleaning system would often leave boards needing additional hand scrubbing," commented David Martin, PCB operator.

The cleaning system is guaranteed to remove fluxes, including no-clean fluxes, without the problematic white residues associated with traditional mono-solvent and semi-aqueous processes.

The non-aggressive nature of the hydrocarbon solvating agent means that there are no material compatibility problems when cleaning populated boards.

The co-solvent process also removes both the oily film that occasionally coats unpopulated boards received by ETL, as well as aged solder pastes on misprinted circuit boards.

The Microsolve system's low solvent consumption was a major attraction for ETL, as was its conformity to health and safety and environmental requirements.

The reliability of Kerry solvent cleaning systems also proved decisive.

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