Ultrasonics clean up PCBs for aerospace use

General Dynamics has been won over by the ability of a Kerry co-solvent ultrasonic machine to remove flux from printed circuit boards destined for the aerospace industry.

General Dynamics United Kingdom, formerly known as Computing Devices, has been won over by the ability of a Kerry co-solvent ultrasonic machine to remove flux from printed circuit boards destined for the aerospace industry.

Following rigorous testing, the cleaning system was fitted with the Kerry Neptune microprocessor controller for the Pulsatron P500 generators, which allowed the ultrasonic transducers to run at either 38kHz or at 70kHz.

70kHz has previously been shown to cause no damage to wire-bonded devices.

The dual frequency switchable operation of the transducers, allied to the fact that the co-solvent process can operate both with and without ultrasonics, allowed General Dynamics to develop its use of ultrasonics over time.

Ultrasonics has been found not to be required on products containing fine-pitched or wire-bonded devices.

General Dynamics had experienced difficulty drying pcbs at the end of its previous semi-aqueous cleaning process; the hydrocarbons would not rinse out of fine pitched components.

This problem was solved by using a co-solvent process with a very effective hydrocarbon wash, followed by a rinse in volatile low viscosity fluorocarbon solvent which left the components clean, free from hydrocarbon residues and dry at the end of the cleaning cycle.

The entire process is automated with the Autotrans Mk4 robotic work transporter, ensuring optimum throughput efficiency at all times.

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