What exactly is a “lead free label”?

The strictest definition is that it is one that contains no lead, or other heavy metals such as Chromium, Cadmium, Mercury, organo-tin compounds, and the like which are harmful to not only human beings, but also to the environment. However, in the context of today’s “lead free manufacturing processes” embraced by the electronics industry and the European Union, it has a much wider meaning. “Lead free labels” today means those label materials which not only are “lead free” themselves, but which are also designed to be used in the new manufacturing processes, which oftentimes will require higher soldering and processing temperatures.

I believe that almost all labels used today are “lead free” as defined here, i.e. contain no heavy metals. But that is not the main concern, as you will see from Question #2.

What are the implications of these new “lead-free initiatives” for the barcode label systems I currently use?

There are several implications for the users/purveyors of barcode label technologies using labels on or inside electrical and electronic products: Administrative, and Functional.
a. Administrative. You will be required by those companies which want to be in total compliance with WEEE (“Directive 2002/96/EC of the European Parliament and of the Council of 27 January 2003 on waste electrical ane electronic equipment”) and RoHS (“Directive 2002/95/EC of the European Parliament and of the council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment”). End users each have their own format for disclosure of hazardous materials used (if any), and also a complete mass balance of materials supplied by each vendor. Examples can be found at www.polyonics.com/DocsCenter/RoHSSubstances.pdf, and www.polyonics.com/DocsCenter/100PercentMaterial.pdf.

For complete information you may see current events in these areas at http://164.36.253.20/sustainability/weee/index.htm . For the actual legislation you may go to the EU website, http://europe-eu.int/eur-lex . They have a search engine to lead you: use a quick search, and type in “13.2.2003” for WEEE. The 3rd (or so) citation is the document in question, entitled “3b2 to ps.psl..24 WEEE”. For RoHS you will enter “ALL”. Then go to “Search by Document Number”. Fill in “Year =2002”, Number =95” Then the first document shown is the Directive 2002/95/EC…” or the RoHS.

b. Functional. Presumably you or your customer has been satisfactorily been using barcode labels for quite a while. The use of “no-lead” solder will, of necessity, require higher processing temperatures in the soldering step(s), since the solders proposed to date require temperatures of between 20-30°C higher than those used today to be used. This means that thermally marginal components (and do not forget that the barcode label is a component) may become damaged once subjected to these higher temperatures. In the case of a barcode label, the label may shrink (destroy barcode integrity), badly discolor (destroy PCS), or even curl or fall off the board (information not available for scanning).

Existing labels must be re-tested under the new manufacturing environments. Even the venerable polyimide (or “Kapton®”, DuPont’s brand name for its polyimide) labels may not work…all polyimide labels are “NOT” created equal. In some cases, new materials must be used, which are designed specifically with these new requirements in mind. In the worst case scenario, this may mean incremental increases in label costs, to meet these new thermal demands. Such materials have been developed by polyonics, and free samples are available at info@polyonics.com. In the subject line just type in “Lead Free Samples”..we’ll need your name and address of course.

Dr. James Williams, Polyonics founder, has written a complete discussion of these performance issues, which was published in the February, 2004 issue of “Circuits Assembly” magazine. A pdf copy of that article is available free at www.polyonics.com/Documents/LeadFreeArticle.pdf .