PCBs


Supply chain challenges Despite the questionable environmental benefits of reducing halogens, the pressure placed on consumer goods companies and the associated importance of maintaining a positive public image means that OEMs will continue to ask the electronics supply chain to develop halogen-free or at least low-halogen products. These efforts are hampered by several challenges including the absence of a common definition of low-halogen, the absence of inexpensive test methods for verification, performance challenges associated with low-halogen materials, and material costs.


Although IPC does not endorse the


environmental claims associated with reducing halogens, the organization has been actively supporting the development of a guideline defining low-halogenmaterials. While some critics believe that by developing a guideline IPC is endorsing bad science, IPC understands that it'smuch easier (and less expensive) for the supply chain to manufacture to a common, low-halogen definition than to develop products thatmeet a host of differing customer requirements.


That'swhy,when approached by several of itsmembers, IPC


formed a task group to develop a common definition of low-halogen electronics. The draft guidelinewill build on the existing IPC specifications for low-halogen printed board laminates. The draft guideline does not comment on the environmental benefits (or lack thereof) of low-halogen electronics. It simply seeks to provide a common definition of low-halogen for the electronics industry.


Another challenge hampering the supply chain is the limited


number of existing testmethods. If all you want to do ismeasure the concentration of all halogen atoms in your product, you have severalmethods available.


Simple X-ray fluorescence can be used for non-destructive


screening. Although the precision of this test is limited, the equipment is improving daily. For more precise concentration results, flame atomic adsorption, is fairly inexpensive and straightforward, although destructive.


However, if you want to test the presence of halogens in specific


compounds, such as brominated flame retardants (BFRs) or polyvinyl chloride (PVC), there is a lack of commonly accepted methodologiesmaking it difficult to verify the reduction of halogens associated specifically with BFRs and PVC.


Although a number of reduced-halogen laminates are available


for printed board manufacture because of special market demands, they have not been developed for all products. These materials can be significantly more expensive and the current


34 | April 2011


production capacity is by far too small to cover the full demand. Some reduced-halogen base materials rely mainly upon a


phosphorous-modified epoxy in combination with Al(OH)3 to provide flame retardancy. Risk assessments of the phosphorous components have not been sufficiently carried out. In addition, not all TBBPA-modified epoxy resins can be substituted by low-halogen components.


Many printed board manufacturers


and end users of printed boards will also not be able to afford the significantly higher costs for low- halogen laminates. In addition to facing higher materials costs, since some electrical and dielectrical properties of halogen-free materials are different compared to those based on TBBPA as a flame retardant, industry will need to redesign many printed circuit boards.


In addition to TBBPA, many


halogenated substances have critical functions in electronics products,


including solder flux and flame resistant coatings. Fluxes used for soldering most often contain organo-halides as activators. Although other activators (acids, amines) can be used to dissolve oxides, this can be too slow to compete with re-oxidation during the soldering process (up to 260°C).


Also, the quantity of other activators that can be used is limited


in solder pastes because of product stability. Generally, omitting halogen fromthe flux severely reduces the product process window, particularly for lead-free soldering. The reduced process window leads to an increase in the number of unsatisfactory solder joints, jeopardizing the reliability of the joint and hence the finished product. Organofluorine compounds, which are inherently flame resistant, and coatings are used for wire insulation, oil-free bearings and non-stick surfaces. There are no alternatives formost applications.


NGOs have devoted a lot of resources pressuring companies to


remove halogens fromproducts. Their failure to obtain restrictions on halogens under the revised RoHS Directive is just aminor speed bump for NGOs in their quest to regulate halogenated substances. Therefore, despite the questionable lack of environmental benefits of reducing halogens, the electronics industry is likely to spend the next decade attempting to address the challenges associated with low-halogen electronics.


For more information on IPC environmental initiatives, visit www.ipc.org/ehs or contact Fern Abrams, IPC director of


environmental policy and government relations, at fernabrams@ipc.org.


www.electronics-sourcing.com


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52