Datasheet

3
Lead Free Soldering
with Weller Tools
In support of the global drive to reduce
enviromental pollution the European
Community's RoHS legislation came into
force on July, 1st 2006. A key element of
this legislation is the requirement to
remove lead from the soldering process.
Why Lead Free Soldering?
WDC 2 Dry Cleaner
Order No.: 005 15 125 99
Grindstone WPB1
Order No.: WPB1
Weller has extensive experience and
knowledge of lead free solder. This has
been gained through working with our
customers in Japan and China who have
been using Weller equipment and lead
free solder for many years. Weller’s ‘Silver
Line’ technology is proven in both terms
of its quality and its performance. Your
company can benefit from our knowledge
and experience.
Why Weller?
Lead free solders use new allows which
have higher melting points than traditional
lead solder (217°C to 227°C). When com-
pared to solder joints containing lead
these new alloys create solder joints which
appear dull and are more temperature
sensitive during the hardening process.
An increase in process temperature should
be avoided as longer cooling times may
cause micro cracks. Soldering with higher
temperatures can result in black layers on
the tip which make them unwettable and
cause early fallout (charred flux, oxidized
tin, tin-iron-fusion). Thus, new materials
like lead free alloys demand new tools.
Attributes of Lead Free
Solder
Due to higher melting points, working
with lead free solder requires:
Tools with better thermal conductivity,
to minimise heat loss from the tip of
the iron.
Optimised tip selection. More short
and thick tips are preferable to trans-
fer the required heat into the solder
joint without increasing the process
temperature. Thermal stress on compo-
nents and PCBs is reduced and the
solder tip is protected from damage
(lifetime, wettability).
Cost reduction of consumable parts.
Requirements for Hand-
Operated Soldering Tools
Select the lowest possible working
temperature.
Ensure the optimum heat transfer
between tip and solder by using a well
wetted tip.
Soldering in an inert gas environment
increases the flow behaviour and
reduces the need of flux; don’t use
more flux than is needed.
Work with soldering tools that offer
high power and optimal thermal
transfer.
Use an intelligent soldering station with
optimised temperature control and a
setback function to reduce the tip tem-
perature when the iron is not in use.
Preheat the boards with hot plates
before repairing to reduce the solder-
ing time.
Make sufficient tests and create a
detailed flow chart to establish the
steps needed for a successful transition
to lead free soldering.
Clean the tip with the Weller WDC
Dry Cleaner.
Add sufficient tin to the tip before
placing the iron into the stand.
Unwettable tips can be reactivated
with Weller Tip-Activator.
Apply as little force as possible onto
the tip.
Black layers of oxidized tips can be
softly removed with steel or aluminium
wool.
Hints for Soldering
WDC Dry Cleaner
Order No.: 005 15 124 99