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Polyimide Labels in Lead Free Soldering Applications.....Requires Higher Solder Temperatures
Higher temperatures can adversely affect ordinary polyimide labels in use today...
The photos below show the effects of extended time and temperature ( 277 °C for 50 minutes) on a "standard" polyimide label from a competitor, compared to a new generation polyimide label XF 581 and 582, designed for the higher temperatures required.
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Polyonics XF 582 Competitor's Polyimide Label |
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The European Union's Waste of Electrical and Electronic Equipment (WEEE) and Restriction of Hazardous Substances (ROS) strongly suggests that lead-free electronic assemblies will be mandatory in Europe by 2008. Japan is moving toward voluntary compliance by 2003 with a lead-free initiative that focuses on environmental marketing of new products such as mobile phones, consumer electronics and automotive electronics.
Lead-free solder require higher processing temperatures than traditional tin-lead alloys, which most certainly will affect polyimide labels for circuit board ID. In general, fluxes used for lead-free flow soldering must be able to withstand topside PCB preheat temperatures as high as 130 °C and solder temperatures as high as 280 °C for a minimum of 3 seconds of contact time or longer. |
PREHEAT CYCLE: For most lead-free flow soldering applications, the topside PCB temperature will increase by as much as 125% to approximately 110- 130 °C to limit the thermal shock as the PCB contacts the higher temperature of the lead-free molten solder.
SOLDER POT: The solder pot temperature will be as high as 260-280 °C for Tin-Copper solders.
Each label material used must be re-evaluated against these new thermal profiles. If polyester was used in a location, which now experiences the higher temperatures (and renders it useless), then the label must be changed to a different material, such as PEI or Polyimide (Kapton) label material. The higher temperatures may also require that standard polyimide labels be changed to new polyimide labels specifically engineered for these lead-free processes. |
Get more information on the new Polyonics THERMOGARDŽ 1 mil polyimide labels for lead free soldering and 2 mil polyimide labels for lead free soldering.
FREE SAMPLES AVAILABLE at Lead Free Polyimide Samples.
In all cases, TEST, TEST, TEST the existing barcode labels, as well as any new circuit board labels proposed for use. You can find a more detailed discussion of these issues at LEAD FREE DISCUSSION. Or, go to www.polyonics.com/ and click on the FAQS page. You will see a heading for "Lead Free Initiative".
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