Higher
temperatures can adversely affect ordinary polyimide labels in
use today...
The first photo shows the effects of extended time and temperature
(300°C/572°F for 30 minutes) on a "standard"
polyimide label from a competitor, compared to a new generation,
lead free polyimide label XF 581 and XF 582. The 58 series of polyimide
labels are designed for the higher temperatures required for lead
free soldering processes.
Polyonics XF 582 Competitor's
Polyimide Label |
|
The
second photo shows XF 552 polyimide label material after heating
under the same conditions, compared to a competitor's white polyimide
label, heated under the same conditions. The XF 552 undergoes
NO color change...it remains the same "school bus yellow"
color that it was prior to heating
.
The
European Union's Waste of Electrical and Electronic Equipment
(WEEE) and Restriction of Hazardous Substances (RoHS)
mandates lead free electronic manufacturing by August, 2006...that's
1 year away. .
Lead-free
solder requires 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% from 50-60 °C,
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, compared to 220-240 °C
required for ordinary lead-tin solders in use today.
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.
Data sheets and
samples are available for the new Polyonics THERMOGARD™:
1
mil white polyimide labels (gloss) for lead free soldering
2
mil white polyimide labels (gloss) for lead free soldering
1
mil white polyimide labels (matte) for lead free soldering
2
mil white polyimide labels (matte) for lead free soldering
2
mil yellow polyimide labels for lead free soldering
FREE
SAMPLES AVAILABLE are 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, click on the FAQS
page. You will see a heading for "Lead
Free Initiative".
