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40 SMT Magazine • September 2017 is the removal of residual solder on top of the components board land pads. It is necessary to properly reinstall a new component onto a defined surface and achieve repeatable and reliable soldering results. Today's hand-operated methods are related to the operator's skills and thus are a hidden risk. A manually operated, but non-contact residual solder removal module has many benefits: • repeatable process and non-contacting suction of the solder • no risk of pad damage or rip off • no solder mask damage • no contamination of the PCB with flux or solder residues The method is to use a gentle air flow along with the PCB bottom side preheating to melt the remaining solder on the PCB and suck off the liquid solder with a vacuum nozzle shortly above the PCB surface (Figure 3). Besides the known technology of melting the solder with a gentle air flow and cleaning off the solder from the PCB with vacuum, it is necessary to control the height above the PCB in order to keep the boards undamaged. In first applications the height adjustment will be manual, in advanced systems there will be an automatic height adjustment based on pressure control or with a laser triangulation sensor. Solder separation and flux filtration as well as an acceptable maintenance of the unit are crucial features for successful daily operation. This module cannot be seen as completely independent from a rework machine, but an integrated part. The board temperature should be known and the PCB bottom side preheating must be active and controlled during the process. Operator Guidance—Software Assisted Operation The market clearly asks for flexible and easy to operate rework systems and at the same time for high automated, user independent equipment. For all of them a clearly structured interaction with the operator or the system administrator is essential. One clear customer expectation towards rework processes is achieving user-independent, high-quality results. This is why more auto- mated process steps are implemented into rework units and improvements on the HCI (human computer interface) are requested. It is obvious that operator guidance and assistance is decreasing operator failures during the rework procedure. Clearly structured software surfaces provides all necessary information along BTC AND SMT REWORK CHALLENGES Figure 3: Scavenging system for residual solder removal during SMT rework and mounting.