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Written by Mike Buetow   
Saturday, 31 January 2009 19:00
Caveat Lector

You’re still here?

Sorry; in times like these, it’s no doubt impolitic – not to mention impolite – to joke. Call it gallows humor.

But there’s something to be said if, after the thousands of layoffs and some high-profile bankruptcies – Nortel being the most recent – you still have your job as you read this.

Some victories are hollow, indeed.

As if we haven’t spent enough in time and expense on massive transitions of dubious environmental value (read: RoHS), there is, pending IPC and Jedec member approval, a draft standard establishing maximum limits for bromine and chlorine in low-halogen electronics components and assemblies. Per the standard, brominated and chlorinated compounds are “most common and also the most likely to be present to achieve flame retardancy, and therefore are the elements for which limits are established.” (Fluorine and iodine are not covered by the pending spec.)

Much of this rides on homogenous materials. As with RoHS, one issue is just what counts as a “compound.” Bromine or chlorine in materials used during processing or packaging, but which are deleted or otherwise disposed of from the final product, are not included. Those materials that remain in the final product, such as flux residues, are covered.

Yes, there are halogens in soldering fluxes, and in the past year we’ve seen suppliers launch halogen-free products. As with any new technology, there are drawbacks. In place of traditional flux chemistries, low halogen versions using organic acids or bases are popping up. The rub is they contain more activators, which do not remove oxides as well, which in turn increases the likelihood of corrosive residues.

That IPC is abetting the halogen limits movement is odd. The trade group wrote an open letter last March to the organization charged with assessing potentially hazardous substances for possible inclusion in supplemental legislation to the RoHS Directive to table its efforts until further scientific evidence is available to support a ban. In that letter, IPC wrote, “IPC urges the Oko-Institut to avoid restricting additional substances to the RoHS scope while industry, governments and the public are still facing a variety of implementation challenges. … Any expansion of the RoHS scope must be thoroughly reviewed for technical feasibility.”

Twice referring to the Oko-Institut’s actions as “arbitrary and capricious,” IPC asserted the institute mistakenly included TBBPA (Tetrabromobisphenol-A), a bromine-containing flame-retardant used in laminate, on its list, despite the substance’s having passed a recent EU risk assessment. “The shift from lead-bearing solder alloys to lead-free alloys has created reliability concerns within solder joints,” IPC wrote. “The high tin content solder joint may be stronger, [but] the thermal stresses applied are transferred to other locations within the assembly, causing failures within the board or the components.”

In response to Circuits Assembly's questions, IPC said, “IPC is completely opposed to legislative policy that is not based on solid science and stands behind its statement that the Oko Institut's report lacked a scientific basis, particularly in regards to the proposed ban on TBBPA. There is a fundamental difference between non-voluntary legislation and voluntary standards. J-STD-709 standard does not state an IPC position.” IPC is taking a highly disingenuous stance here, however, analogous to writing a letter, signing your name, then saying the contents don't represent your thinking.

Per a January task group meeting, J-STD-709 would call for limits on each plastic within the component of <1000 ppm (0.1%) bromine (if the bromine source is from brominated flame-retardants] and <1000 ppm (0.1%) of chlorine (if the chlorine source is from CFRs or PVC). Higher concentrations are permitted in plastics of components other than board laminates and substrates provided their sources are not BFRs, CFRs or PVC.

Yet it is questionable whether there are supporting data for the proposed limits. As one committee member told me, “When I ask, ‘How did you come up with 1000 ppm and to what test method?’ I have been told we are not concerned with testing.” But, as the committee member points out, “the two go together. They are setting standards that do not have test methods or sample preparation techniques. It is the most non-spec I have ever seen.”

Or, one might say, arbitrary and capricious.

The counter-argument will certainly be made that this standard is not intended to cover all end-products, but only those that seek the low-halogen classification. We've seen this play before. It’s the first step toward pushing all products toward low-halogen status. As was the case with lead-free components and alloys, it’s too expensive for suppliers to maintain boatloads of product lines. Eventually, they’ll capitulate, and the entire supply chain will pay the price.

Standards themselves shouldn’t get ahead of the market, let alone any legislation. And certainly standards should not be used to create a market. If end-customers want to go halogen-free, let them decide to do so. But don’t hoist yet another massive tax on an industry already staggering under the weight of a global financial meltdown.

 

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