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www.us-
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Selective Soldering Continued from 63
Rosin does leave a residue on
the board that can contaminate man- ufacturing equipment, which is more of a threat to circuit boards than the reliability issues of water-soluble fluxes. Although with the high demands of today’s electron- ics, rosin residues can also lead to failures in harsh envi- ronments. The
cleaning
process for rosin can be an expensive process to operate and also usually requires a solvent that brings its own complications.
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30+ years of experience manufacturing electronics and much more.
Low-Solids/No-Clean Flux. These types of fluxes were em - ployed so that cleaning could be eliminated. Initially, low- solids/no-clean fluxes were essentially rosin-like fluxes, but with less rosin. Today, these flux- es are much more sophisticated. But, the principle is that with less chem- istry, there will be little-to-no active chemistry left on the board after the soldering process. So rather than the 35 percent solids in a full-rosin flux, low-solids fluxes range from 1.5 to 8 percent. With less chemistry, the issue then becomes having enough active chemistry to be an effective flux.
Note that low-solids fluxes are
not necessarily “no-clean” for every application. The same flux and res - idues may be perfectly safe in one application, and very harmful in another. It is up to the customer, the product designers and anyone who understands the demands of the end- use of the product to decide the type of flux. Even in small amounts rosin is
used as a way to avoid adding active chemistry to improve performance. It is a key ingredient in many of these low-solids fluxes, as it helps to protect the cleaned metal and the little chem- istry in these fluxes during the solder- ing process. It allows the flux to with- stand a longer, hotter exposure to heat than without it. There may be slightly more residue with rosin in the flux, but the idea is that any remain- ing chemistry will be contained by the rosin. Even so, some customers find any residue visibly undesirable or unsafe to leave on the board. Not only are these fluxes good
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in long preheat/heat exposures or higher-heat processes, they also work well in low-heat applications or short processes as the alcohol evapo- rates quickly, allowing the soldering to begin almost immediately. To address this issue, most flux
manufacturers offer low-solids fluxes with no rosin at all, which tends to allow the active flux to volatilize more completely during soldering and leave the least amount of residue. As a result, however, these fluxes do not last as long because they are not shrouded by rosin. For selective soldering this can be a prob- lem, as exposure to elevated or high heat can be relatively long in some cases. These fluxes may be depleted by the time they are soldered. Leaving a little rosin in the flux helps to combat the heat issue as well as to encapsulate remaining ionic residue. VOC-free, low-solids/no-clean fluxes are similar in that they do not
Flux containing rosin can act as a protective barrier against ionic residue damage.
more active. To conclude, low-solids/no clean
fluxes with a small amount of rosin, or a synthetic equivalent, are usually the best choice for selective solder- ing. This type of flux has a wide process window and offers a higher chance of success when working with a variety of products and programs that require ranging temperatures or very high heat. Contact: Pillarhouse USA, Inc.,
201 Lively Boulevard, Elk Grove Village, IL 60007 % 847-593-9080 fax: 847-593-9084 E-mail:
sales@pillarhouseusa.com Web:
www.pillarhouseusa.com and Selective Solder Academy, 201 Lively Boulevard, Elk Grove Village, IL 60007 % 224-659-7086 E-mail:
info@solderingacademy.com Web:
www.solderingacademy.com r
iTAC Exhibits Smart Factory Software
Southfield, MI — iTAC Software is offering a variety of advanced plan- ning and scheduling, business intelli- gence, and real-time factory dash- boards. The next revolution in manu- facturing involves the creation of smart factories that use Internet of Things (IoT) solutions to achieve new levels of productivity and efficiency. The company has released the latest version of its
iTAC.MES.Suite, which is designed to use IoT technologies to serve as the nerve center of the smart factory. Other products offered by iTAC
include its Advanced Planning & Scheduling software, which uses machine, material, tooling, and worker constraint data to automati- cally create optimized production schedules; the
iTAC.BI.Portal, which is a web-based business intelligence solution for delivering interactive big data reporting and analysis; and 2D and 3D dashboards that contain cus- tomizable visualizations displaying up-to-the-second KPIs. Contact: iTAC Software, Inc.,
Dürr Campus, 26801 Northwestern Highway, Southfield, MI 48033 % 248-450-2446 Web:
www.itacsoftware.com
See at IPC APEX, Booth 2619
February, 2017 Choosing the Right Flux for
have rosin, but because they are water-based they handle exposure to heat better and tend to be a little
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