Canoga Park, CA — Ultrasonic cleaning frequency is important; so is the equipment maker and the cleaning medium when cleaning Durostone® pallets, according to an evaluation by Durostone maker Permali Composites S.A. The company subjected its pallets to ultrasonic cleaning using Smart Sonic Ultrasonic Stencil Cleaners and 440-R® SMT detergent cleaning flux residues from reflow and wave solder pallets.
|Ultrasonic cleaning system from Smart Sonic. |
The test run was important because previous attempts using other equipment did not give good results. In fact, Durostone had previously advised customers not to clean its Durostone solder pallets using ultrasonic equipment as it seriously degraded the material and left it susceptible to flux attack, reducing the life-span of the pallets. Two cases had been reported but in both cases, the ultrasonic machines did not come from a manufacturer supplying the PCB industry.
Tests were carried out in conjunction with a major ultrasonic cleaner manufacturer, Smart Sonic Corporation of Canoga Park, California. A batch of pallets covered in a no-clean flux were submitted to Smart Sonic for cleaning and returned to the customers' production line. Following cleaning of the pallets, no degradation occurred so it was concluded that given the correct equipment and process settings, ultrasonics does not affect Durostone.
The pallets cleaned at Smart Sonic were cleaned at a frequency of 40kHz or higher, with a power input of 11 watts per liter or less, and (12-15 watts would also be all right — in a wash cycle of 10 minutes or less.
The final conclusion was that the past problems occurred due to the material being subjected to a low frequency — below 40kHz. The lower the frequency, the more aggressive the ultrasonic cavitation. Simply put, do not clean Durostone using a frequency below 40kHz. What works well is using high frequency/low power ultrasonics, and an effective cleaning chemistry. The tests at Smart Sonic were successful using the company's 440-R SMT Detergent.
Contact: Smart Sonic Corp., 6724 Eton Avenue, Canoga Park, CA 91303 818-610-7900 fax: 818-909-6109 E-mail: Bill@SmartSonic.com Web: http://www.SmartSonic.com or http://www.SMTdetergent.com