A brief summary of
various wave soldering (common) combinations & options is summarised below
together with the effect on the EVS process.
| Fluxes
- |
Low Rosin |
No problem possible
|
| |
High Rosin |
Watch the fumes!
Minimise exposure when lifting loading flap. Ensure regular filter
maintenance. Cylinder maintenance needs to be regularly performed.
|
| |
No Clean |
Should be no
problem |
| |
No Clean
(rosin) |
No problem |
| |
Organic Acid
(water sol) |
Watch the fumes!
Minimise exposure when lifting loading flap. Ensure regular filter
maintenance. Cylinder maintenance needs to be regularly performed. |
| Waves
- |
Single Lambda
|
Standard machine
used for soldering PTH |
| |
Single Oscillating |
Adaptation of
above in attempt to solder SMD - produces slightly more dross than
single Lambda |
| |
Dual/Chip |
Most common
way of wave soldering SMD's. The "chip" wave by its nature produces
large amounts of dross. A common problem is dross blockage
of the chip wave producing an uneven solder wave. This can be exaggerated
by leaving dross on the surface of the solder wave. Regular de-drossing
is important. |
| |
Kirsten |
Don't bother.
Small volume machine uses oil to lubricate wave. |
|
Treatments - |
Wave Oil
|
Do not load
oil laden dross into the EVS. The SRS will allow companies to stop
using oil. Normally the use of oil prevents the use of No Clean fluxes.
The EVS can be justified by the savings generated by the cessation
of the cleaning process. |
| |
De-drossing
crystals |
Not that common
in "mature" markets. Crystals tend to be effective when added regularly
and stirred into the solder and dross. This tends to distribute the
crystals and dross throughout the solder bath creating an emulsion.
This may be detrimental to solder joints in some applications. |
| |
Open Nitrogen |
Otherwise known
as a contour wave it is not that effective in reducing dross - typically
15% less dross. Nitrogen can cost up to £1000 a month to run. The
traditional argument for Nitrogen is that it is required to run a
no clean process. No longer true. The modern formulations are more
than capable of supporting NC technology in atmospheric conditions
(try our NC213 & NW85!). The EVS can easily be justified by switching
off the Nitrogen! |
| |
Closed Nitrogen |
Produces much
less dross, but equipment is very costly. Some customers have still
bought EVS to handle the dross produced by the closed N2 system. This
was not done on ROI however. |
| |
Hot air
knife |
Used to debridge
pcbs the hot air knife can actually produce serious amounts of dross.
The cost of reworking is such that the cost of producing the dross
can be discounted. With the EVS the customer can have the best of
both worlds!
|
