Guyson Microsolve eliminates nPB from the defluxing of electronic PCB panels
Electronic manufacturing services (EMS) companies looking to eliminate the need to use n-Propyl Bromide (nPB) in the defluxing of their PCB boards and panels can call on leading industrial finishing equipment manufacturer Guyson International for an effective solution to their cleaning problems with the installation of a Kerry Microsolve Co-solvent cleaning system.
At present many PCB panels are still being cleaned using n-Propyl Bromide (nPB) – a solution that in 2012 the European Chemicals Agency (ECHA) listed as a ‘Substance of Very High Concern’ (SVHC) and now n-Propyl Bromide is classified as a CMR product (Carcinogenetic, Mutagenic and Reproductive toxin) by the SED (Solvent Emissions Directive 1999-13-EC). This has resulted in many users having to reduce their nPB fluid consumption volumes or replace nPB within a specified time period. Any company searching for a safe and effective alternative for cleaning their PCB Panels can now come to Guyson for the solution.
Guyson’s ‘Kerry’ branded Microsolve Co-solvent systems achieve cleanliness standards to specifications including BS, IPC [Institute for Printed Circuits], ESA [European Space Agency] and MIL SPEC with or without the use of ultrasonic agitation. The co-solvent process defluxes all types of PCBs, assembled and reworked, removes no-clean solder flux residues, and can also eliminate the white deposits (dependent upon flux age) associated with traditional single solvent and water-based detergent processes.
The Kerry Microsolve Co-Solvent system manufactured by Guyson has four process stages comprising of ultrasonic cleaning, an ultrasonic rinse, vapour rinsing and finally freeboard drying. The Co-Solvent process is intended to replace all VOC solvents (Volatile Organic Compounds) which impact upon global warming and are also classified as CMRs (Carcinogens, Mutagens & Reproductive Toxins).
The Kerry co-solvent system has two ultrasonic, heated stages comprising of cleaning and rinsing equipped with continuous filtration. Cleaning, with or without the use of ultrasonics (some aerospace/military PCB applications may restrict the use of ultrasonic activity within the solvent), is carried out in the stage one tank by immersion of the components into the Co-Solvent mixture, usually comprising of an HFE (hydrofluoroether) and a petroleum distillate based solvating agent.
The solvating agent and HFE are carefully selected by Guyson to suit the client’s particular application either from experience or by performance evaluation cleaning trials on sample components. Large quantities of flux and general contamination can be taken up by the solvating agent, making the process particularly suitable for high volume cleaning with minimal tank maintenance.
Immersion into the stage two rinse tank of pure HFE solvent allows the removal of any residues which might have been carried over on the processed components from the stage one cleaning tank. Both the cleaning and rinsing tanks have the ultrasonic transducers mounted on the tank base, connected to the Guyson Primewave dual frequency generators which incorporate ultrasonic output power control, pulsed operation of the ultrasonics (if required) and frequency modulation and sideband sweep. The Guysonic generator and Primewave dual-frequency controller offers cleaning at ‘standard’ frequencies of 36, 66, and 146 kHz, either single or dual frequency operation, and enables all sensitive or intricately shaped parts to be cleaned effectively.
Stages one and two are each supplied with solution heating and a pumped closed-loop filtration system comprising of a coarse strainer, fine filter cartridge, welded pipework and “O” ring sealed valves to minimise any possibility of solvent loss.
Stage one electrical heating is controlled in a unique operation that monitors the running temperature of primary refrigerated distillate cooling coils and effectively results in pulsed operation of the heating. This ensures that the vapour blanket above stages one and two is efficiently maintained to avoid solvent emissions. Primary rinsing is carried out by immersing the PCBs into stage two and this is followed by a final rinse in the vapour zone (distilled clean HFE solvent) located above both tanks. Drying then takes place while the components are located in the freeboard area, where the solvent evaporates almost instantaneously back onto the refrigerated distillate cooling coils situated above the two process tanks and around the perimeter of the freeboard zone.
Low, predictable running costs
The Microsolve has well proven and established unique solvent retention features which provide economic benefits through the efficient control and use of HFE solvents. Microsolve owners enjoy low, predictable running costs thanks to intelligent machine design - a highly effective refrigerated reflux cooling system, vapour break and an increased freeboard zone all help to prevent the potential high running cost through minimising evaporation of the HFE solvent. An optional automatic HFE top-up system logs the rate of solvent usage to provide factual information regarding the total consumption over a 30 day period.
The Autotrans Mk5 robotic work transfer system ensures consistent, repeatable quality whilst increasing throughput and also contributing to minimising solvent usage by controlling the speed of basket movement through the vapour zone. This operation reduces any solvent drag-out caused by disturbance of the vapour blanket. All Autotrans transporters can integrate with feed and exit conveyors or load and unload tables for fully automatic operation and are supplied with guarding to comply with CE regulations for moving parts, with various options to suit machine location, factory layout and operating procedures.
Cleaning trials
Prospective users of Guyson ultrasonic cleaning equipment are encouraged to submit sample components for free feasibility testing in the company’s extensive demonstration centre at Skipton, England. For further information regarding the Microsolve range of equipment and processes or specific information regarding low solvent running costs please contact Guyson International on +44 (0)1756 799911 or email info@guysonfr.co.uk