Vapour phase or convection for lead-free?
Table 1 shows some materials which
were available originally for use in vapour
phase units.
Today the supplies are limited, and the
primary material for lead-free may be either
230 or 240˚C from Galden Materials. Ma-
chines are available in the UK from A&D
Automation
www.adauto.co.uk.
There are still differences in the ΔT
on the board surface and under com-
ponents, but it is very small at the peak
temperatures, provided the time is allowed
for the profiles to converge. The initial
temperature rise through preheat does have
recordable differences just like convection
but can be smaller depending on the ma-
chine design and the effort put in by the
Figure 4. Examples of the VPS batch system from Gen 3 Systems (www.gen3systems.com). Inline systems from
IBL represented in the UK by AD Automation.
engineer to optimize the process.
Cooling can still be a delay in the pro-
cess, just like standard convection reflow.
However new developments in liquid cool-
ing may benefit the industry, convection
cooling is of course still used on systems.
A new interactive CD-ROM on ‘Lead-Free
Reflow Soldering’ has been developed by
ITRI/Soldertec. It is one of three training
CDs covering lead-free wave, reflow and
hand soldering, available together as a
special set.
Table 1. Materials originally available for VPS
Manufacturerp Boiling point
FC70 215˚C
FC5311 218˚C
Galden LS 228˚C
Galden HS 255˚C
Bob Willis is a process engineer working in the
electronics industry, providing training, consul-
tancy and product failure analysis. Bob offers
workshops on lead-free on site for customers. He
runs production lines for suppliers at exhibitions
and also provides seminar and workshops world-
wide. For further information on lead-free train-
ing workshops, training materials and lead-free
process support visit
www.ASKbobwillis.com
Figure 5. Profiles above shows the temperature cures for a double sided product featuring fine pitch, BGA, 0603,
0201 and intrusive reflow connectors.
6 – Global SMT & Packaging – December 2008
www.globalsmt.net
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