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Publication Date: 07/1/2007
Archive >  July 2007 Issue >  Electronic Mfg. Services > 

Sunburst EMS Adds Cost-Effective Selective Soldering
A.C.E. KISS 102 selective soldering system.

High-mix manufacturing is a fact of life for practically any EMS. The great range of product types, as well as assembly and rework applications requires great flexibility, as well as capability, on the part of the EMS provider. The production manager learns to accommodate, innovate, invent, cope, or compromise, to get the job done right. Now, with the conversion to lead-free soldering, there are bound to be dual assembly processes going on at the same time on the shop floor — rework or servicing of older Sn/Pb assemblies, and assembly of all-new Pb-free products. It's tough enough to prevent cross-contamination; but aside from that, how does the manufacturer accommodate both types of assembly seamlessly? Selective soldering is a necessary process for any EMS; there are enough through-hole, mixed technology, custom, and connector-laden assemblies out there to require at least one selective soldering system on the shop floor. When Sunburst EMS began switching over to lead-free electronics assembly, Andrew Chase, President and CEO, was looking for a simple, flexible selective soldering system that would allow transitioning to lead-free without fear of cross-contamination. Also a search was on for a way of handling higher volume and automating a number of soldering tasks that were being done manually. After a comprehensive search among available equipment and vendors, Sunburst chose A.C.E. Production

Technologies' KISS 102 Selective Soldering machines, for reasons that included simplicity, lead-free compatibility, comparatively low initial investment, and simplified automation with easy programming.

Additional Applications
Sunburst's production engineers soon realized that in addition to the intended uses of the machines, there were many more applications for this new soldering technology. Initial goals were to reduce labor costs, and speed up production, through automating a number of difficult soldering tasks that had previously been done by hand, with individual solder fountains, or through the use of custom pallets on a wavesoldering machine. In both instances, separate pots were required for lead-free and lead-bearing solders, requiring duplication of equipment. With the wavesoldering machine, there was always concern about cross-contamination, and degradation of the machine's impellers and parts by the lead-free alloys; never mind the cost of cleaning the machine and preparing it to run a different alloy type; it simply wasn't practical.

"Once we installed the A.C.E. system, we were able to complete many soldering tasks much faster, as we had anticipated" Chase says. "But more importantly, our ability to automate the process has brought greater consistency to the resulting solder connections, since the quality of the connection is no longer dependent on operator skill and variability."

Swappable Solder Pots
The ability to swap solder pots in and out of the machine alleviated Chase's concerns about lead cross-contamination. "As we transition to lead-free assembly, obviously there are going to be some products that still use lead solder, while the newer ones do not" he says. "Being RoHS-compliant is important to us. There are a lot of issues associated with lead cross-contamination, product reliability issues as well as regulatory compliance." Keeping lead-bearing and lead-free solders separate is simplified with quickly swappable solder pots, an innovative feature of the KISS 102 systems. "This capability is especially important to us since we have been certified to ISO 13485." ISO 13485, published in 2003, is an important quality management standard and represents the requirements for a comprehensive management system for the design and manufacture of medical devices.

Prior to acquiring the ACE machine, Sunburst relied on a wavesoldering machine to handle its through-hole soldering. The wavesoldering machine, however, is filled with lead solder and used for many through-hole assemblies that still require lead. Also, it was less flexible than a selective soldering machine. It required custom pallets for some applications. When Sunburst began building lead-free assemblies, it was realized that another soldering machine was needed — one with more flexibility than the wavesoldering machine. Currently, the ACE machine is used entirely for lead-free assemblies, and the wavesoldering machine for Pb-soldered assemblies. If the need arises to use the ACE machine for lead-bearing solder, the unit has swappable solder pots.
Removable, interchangeable solder pot for both lead-free and lead-containing soldering.

With the KISS 102 system, the user simply has two identical, quick-swappable solder pots, one for lead-based solder, and one for lead-free. The pots are clearly marked and color-coded to prevent mixups. Each pot is equipped with its own solder pump and solder delivery system.

Sunburst EMS is always looking for creative new approaches to solving soldering and board assembly challenges, Chase adds. As volumes have grown, so has the need for greater automation and programmability to handle to ever-widening range of components and soldering tasks, many of which simply cannot be addressed with hand soldering.

Why Selective Soldering?
Electronics assemblers are increasingly turning to selective soldering rather than hand or wave soldering for the same reasons as Sunburst, Craig Curk, A.C.E.'s National Sales Manager says. "Many of today's printed circuit boards are predominantly SMT; however there is often interconnect hardware, displays or other components that are generally soldered either by wave or by hand. The KISS machines will precisely solder only the components necessary without disturbing nearby SMT chip components. Selective soldering is precise, programmable, fast, and consistent."

The changeover to lead-free solder has many board assemblers faced with having to spend upwards of $100K for new lead-free compatible wave solder equipment and often additional money for a high capacity nitrogen installation. Multiple RoHS compatible KISS systems can be installed for less than the price of most new wave solder machines. The machine has programmable motion and a PC-based control system. The operating system is easy to use and provides the capability to program a virtually unlimited number of points or areas to be soldered and to store the parameters to be recalled as that job is set up again in the future. CAD files are used either offline or at the machine to teach the datum points. Programming can be accomplished by teaching on the machine using the built-in laser position indicator. PC boards with hundreds of points to be soldered can be processed automatically in a matter of minutes with repeatable results. This system provides the flexibility to individually tailor all the necessary parameters. The fountain position, preheat time, traverse speed, and wave height can all be varied uniquely for each device allowing the user to handle the variations of thermal mass caused by ground planes, heat sinks, and large components while still protecting thermally sensitive devices.

The machine has an optional spray fluxer that dispenses a controlled application of flux only to the areas that will be soldered. It can accommodate PC boards from 2 x 2-in. up to 18 x 24-in., and connectors up to 10-in. long. Its footprint is 30 x 32-in. Sunburst EMS is a flexible, full-service provider of a full range of contract electronics manufacturing services, including design, prototyping, PC board assembly, conformal coating, box build, and supply chain management. The company is fully RoHS and WEEE compliant, and has initiated a lead-free roadmap that can be customized to meet those specific business needs for full lead-free manufacturing and production-ready process.

For more information, contact: Sunburst EMS, 70 Pleasant Street, West Bridgewater, MA, 02379 508-580-1881 Web: or ACE Production Technologies, Inc., 3010 N. Industrial Park, 1st Street, Spokane Valley, WA 99216 509-924-4898 E-mail: Web:

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