Enabling Halogen Free Electronic Assemblies
Posted 02/06/2013 by $username
Halogens in Electronic Devices
There is an increasing awareness of the use of halogens as flame retardants in electronics assemblies and their potentially negative impact on the environment at the end of an electronic device’s useful product lifecycle. The RoHS list of restricted materials includes two formerly common types of Halogen Flame Retardants: Polybrominated and Polychlorinated Biphenyls.
RoHS declarations specify that these halogen bearing flame retardants are not intentionally added to soldering materials. There are no current regulations against other covalently bonded halogen compounds.
However, NGO’s like Greenpeace have disclosed OEMs whose products contain halogenated flame retardants and PVC. Companies who made a commitment to reducing or eliminating PVC and halogens from their products were rewarded with increased green ratings.
Alpha’s Extensive Offering of Halogen-Free Product Technologies
See the list below of Alpha halogen-free products for SMT processes:
ALPHA® Lead-Free Solder Paste: a series of products to meet a variety of challenging process requirements:
OM-338: minimizes concerns in tin-lead to lead-free transitions while delivering excellent ultra fine feature printing repeatability on a broad range of board designs.
OM-340: delivers excellent ultra fine feature print definition with excellent in circuit pin test yields and head-in-pillow (HiP) resistance.
CVP-390: delivers low voiding and excellent first pass ICT pin test yields and electrical reliability for fine feature printing challenges.
CVP-520: delivers low temperature SMT processing that can eliminate an extra wave soldering step when sensitive through-hole components are used.
PoP-33: designed to minimize expensive rework and scrap by providing highly repeatable paste volumes to BGA memory packages.
PoP-707: engineered for use as a dip flux for BGA packages; delivers even, reproducible volumes of flux onto spheres that have been dipped into the flux.
ALPHA® Flux Coated Preforms: extensive offering addressing a broad range of applications, including flux versions that meet the important halogen-free classification; available in a variety of shapes, including washers, sleeves, discs and rectangles.
ALPHA® Liquid Soldering Flux:
6850-HF: innovative low solids, alcohol based, no clean flux formulated for both standard and certain thicker, high-density PCBs; designed for low bridging, superior pin testing performance and excellent hole fill.
SLS-65C: an active, low solids, no-clean flux formulated with a proprietary mixture of organic activators which reduce the surface tension between the solder mask and the solder; to dramatically reduce solder ball generation and solder bridging.
ALPHA® Telecore 850-HF Cored Solder Wire: complies with the IEC and JPCA halogen content specifications; meets highest industry standard for reliability; fast wetting and low flux splatter.and fume levels; operator friendly.
More Information on Halogens in Electronic Assemblies
Halogen Content Industry Standards
The International Electrochemical Commission standard allows up to 900 ppm each of Br and Cl, but no more than 1500 ppm combined (IEC 61249-2-21). The Japan Printed Circuit Association uses 900 ppm Br and 900 ppm Cl as the standard.
Halogenated compounds are commonly used in PCB laminates and are found in many solder pastes. Halogens in solder pastes can allow paste flux to survive the longer, hotter thermal excursions of lead-free soldering.
More modern paste formulations are available that eliminate halogens. One has to ask why 900 or 1000 ppm halogen is acceptable when 0 intentionally added halogen formulations have been on the market since 2003.
Another issue is measurement of the halogen content. In method EN-14582-B, paste is completely oxidized, converting any covalent halogen into its ionic form. However, there is no resolution between halide content before the oxidation/combustion and after. To be accurate, one needs to run an ion chromatograph of a pre-oxidized sample. This is currently not the standard procedure. Most 3rd party labs who conduct the halogen bomb/IC test report a minimum detection level of 50 ppm. However, it has been reported that the gage R&R of this test method may not be very high. Sample size and sample preparation (paste, paste flux or reflowed solder paste) can affect the test results. Zero intentionally added halogen eliminates these issues.