Cleaning is picking up,” says Harald Wack, president of Zestron (Manassas, Va.). By the mid-1990s, flux removal in electronics assemblies was thought to be largely solved by using no-clean (low-reside) flux or OA (organic acid) flux.
Cleaning is picking up,” says Harald Wack, president of Zestron (Manassas, Va.). By the mid-1990s, flux removal in electronics assemblies was thought to be largely solved by using no-clean (low-reside) flux or OA (organic acid) flux. New cleaning challenges are emerging; and with those challenges comes a renewed interest in flux removal.
Why the renewed interest in cleaning? Cleaning issues that had been considered “solved” one to two decades ago have resurfaced within the last two years. Mike Bixenman, chief technology officer at Kyzen Corp. (Nashville, Tenn.), sees the major challenges as miniaturization, higher component density, European directives impelling the use of lead-free solder, and increased functionality requirements. The result is that “we see residues that form conductive bridges and interfere with reliability.” Another challenge is the variable and often conflicting regulatory landscape for cleaning chemistries.
Douglas Winther, president of Technical Devices Company (Torrance, Calif.) has observed that with increasing miniaturization, a major challenge is in getting cleaning agents and water under low-standoff components. “With in-line cleaning systems, you need a correct balance between pressure and flow rate (gpm) on the boards. In terms of our own research, we are adding steam. It is currently available on some systems.” Mr. Winther adds that more aggressive saponifiers will be needed. Edward DePauw, marketing manager, 3M Novec fluids at 3M Electronics Markets Materials Division (St. Paul, Minn.), notes that with miniaturization (lower standoff, higher density, and tighter spaces), there has been greater demand for lower surface tension cleaning fluids.
Mr. Wack explains that until approximately one year ago, perhaps half of industry cleaned electronics assemblies with deionized water. He observes that at the recent national 2010 APEX conference, there was an order of magnitude increase in the number of people urgently needing cleaning/defluxing processes for OA fluxes with a cleaning chemistry (not just deionized water) as compared with 2009. He sees the trend increasing over the next few months and predicts similar changes for those using no-clean (low residue) flux.
An important part of the challenge to electronics assemblers is that if current equipment cannot be retrofitted, new cleaning agents, new cleaning equipment, and thoughtful process development are needed, often accompanied by considerable capital equipment and engineering costs. However, as Mr. Wack explains, “once the investment in process conversion is made, operation costs do not increase markedly. You get a broader process window, one that includes OA, no-clean, and RMA [rosin mildly activated] fluxes. Manufacturers can offer more quality and flexibility to their customers. This helps everyone.”
Generally, an interest in defluxing has increased, with particularly strong growth in Asian markets. “Electronics is a worldwide industry,” Mr. Bixenman says. “We support the manufacturing side, wherever it is.” Mr. Winther comments that “right now, our equipment sales are at approximately 20 percent in Asia and 80 percent in the U.S. Next year, we expect to see 30 percent in Asia.” Electronics assembly and cleaning problems are global. Mr. Winther explains that they have not traditionally cleaned electronics assemblies in Asia; but with increased miniaturization, that is changing. Mr. Bixenman comments that “Some of the larger companies have taken production offshore, but that opens opportunities for smaller shops to stay onshore and fill in the gaps.”
IPC publishes a series of handbooks to provide technical guidance. As chairman of the IPC committee that is combining and updating the post-solder cleaning/defluxing handbooks, Mr. Bixenman envisions the new document, expected to be ready by next year, as “a resource guide to help customers solve their problems. It gives them a baseline—enough information to be able to ask the right questions as to which technical base is the best for them.” Mr. Wack sees the challenge in developing the IPC defluxing handbook as one of distilling disparate individual opinions down to a simple explanation that can be readily understood by the technicians. And Mr. DePauw adds that “the question for the end user is, ‘what’s best for me?’ In some cases it may be aqueous, in other cases, solvent. This handbook should be a practical guide to help end users understand the key factors to consider in their decision-making process.”
To facilitate informed decisions, manufacturers are demanding educational conferences; there was SRO at our recent SMTA cleaning presentation in California and at defluxing sessions at APEX. An IPC/SMTA cleaning symposium is scheduled for November 8th in Chicago. A fall program, in conjunction with IPC, SMTA and SMART, is planned for the U.K.
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