Selective soldering is emerging as a necessary technology for companies that produce circuit boards with a mix of SMT and through-hole components. In the past, the choices for soldering through-hole components have been limited to hand soldering, masked wave soldering, and multi and single tube nozzles for dedicated selective soldering equipment.

The most typical process is hand soldering which often produces upwards of 1000 defects per million opportunities (DPMO). The defects range from insufficient fill due to varying solder dwell times to cold solder joints and missed joints. While labor intensive and hampered by defects, hand soldering is the most widely accepted method for soldering through-hole leads in heavily populated double-sided circuit board assembly.

The Jade Selective Solder system from Pillarhouse (Figure 5-1) is used at the EMPF. The Jade is a flexible, low cost, single point selective soldering system with a large capability. This particular system is designed with an easy to use hand load operation which provides the user great flexibility for quick changes in small batch processing.. It incorporates a board support system that can hold a printed circuit board (PCB) of up to 18” x 20”. While the PCB is loaded and unloaded by an operator, the soldering process is fully automated. The use of an inert hot nitrogen curtain provides localized bottom-side pre-heating to prevent thermal shock and reduce oxidation. Topside pre-heating is provided by four individually controlled, fast-response, medium-wavelength infrared lamps. An optional thermocouple placed on the PCB can provide closed-loop control where the programmer can heat the board under ramp-rate control and maintain the target temperature during soak. When using the closed-loop system, users can choose to use a cooling timer or a temperature setting from the board to determine when the lid can be unlocked and the board is safe to handle.

This system uses a very accurate ink jet fluxing system which has the ability to operate either in a completely separate fluxing program or as part of a simultaneous flux / soldering operation. Solder is applied using a “mini solder wave” which can move quickly and accurately in three axes under the circuit board, controlled by an intuitive, Windows based “point and click” interface.

Options available for the Pillarhouse selective soldering system include a fiducial correction system, an automatic solder wire feed and a level detect system, selective pre-heat, solder wave height measurement system, and separate lead-free solder pot assembly.

For more information related to this article, or to schedule a demonstration of Jade selective solder system located at the EMPF, contact Ken Friedman, 610-362-1200 x 279 or via email at kfriedman@aciusa.org