Plade designed this in-line Automated Cleaner for Flexible Printed Circuits specifically to clean the narrow flexible circuits that are used to connect the main electronics in a Winchester hard disc drive unit to the read/write head. The circuits to be cleaned typically measured 300 mm long by 18 mm wide and were produced from etched copper on Mylar film.The design brief required the machine to automatically transport these circuits through a cleaning procedure consisting of four wet stages and a drying stage. These were a hot detergent pre-soak followed by a hot detergent clean and physical scrub, followed by a hot town water rinse and then a de-ionised water rinse and an air knife and radiant heat dryer.

Double containment was the key to minimising pollution from the machine. The conveyor compartments were constructed, as separate enclosed sections with no direct extraction. These sections were then housed in an exterior sealed structure. A small flow of extraction was provided to the intermediate chamber that had been created and this removed any steam or mist that escaped from the conveyor sections.

The machine was fully self-contained incorporating its own header tanks with temperature control, circulation pumps, conveyor speed control and all necessary internal wiring and plumbing services to carry out the cleaning process automatically.

The machine would be sited in a Class 10,000 cleanroom and should not pollute the surrounding environment through overspray, steam emissions or conducted heat. Extraction volume should be kept to a minimum to avoid loss of room pressure in the cleanroom.Recognising that it would be difficult for the conveyor mechanism to hold position on the flexible film circuit while carrying out a scrubbing procedure, the customer was prepared to allow up to a 10% loss of circuits from the conveyor during cleaning. This tolerance being subject to the provision of a convenient method of recovering lost circuits. During pre-delivery inspection trials at Plade's factory a tolerance of between 1% and 2% was maintained. Lost circuits were also easily recovered at the end of the shift in minutes.This easy recovery of lost circuits was achieved by the use of a combination of gull wing doors to gain access to the inner enclosure and quick release clamps for access to the conveyor compartments.