Fluke Datapaq Reflow Tracker User Manual page 35

Analysis of Wave-solder Temperature
Profiles
For details of analyses that can be performed on a wave-solder profile, see
Insight's Help system (under Contents, select Data Analysis > Wave Solder).
Note that the temperature profiles resulting from reflow and wave-solder ovens
require different analyses, and consequently the data files (paqfiles) which Insight
produces for each also differ and are not interchangeable – nor can a process file
for one type of oven be applied to a paqfile from the other type; see Insight's Help
system (under Contents, select 'Reflow or Wave Solder?').
Checking Profiles
The wave solder process (p. 31) is well understood and generally has a wider
tolerance than reflow soldering. Some of the more common process faults that
can be caused by the thermal profile are listed below. More comprehensive
information is generally available on the websites of the larger wave-solder-
machine suppliers such as Vitronics Soltec or Electrovert.
• Insufficient solder flow – Occurs when the solder has not had sufficient
time to penetrate the holes around the component leads. There are
numerous possible causes, but those that are related to the profile could be
insufficient flux activation due to poor pre-heat temperatures or insufficient
contact time with the wave. In each case, the profile should be used to verify
the temperatures/times against those which are recommended. For the pre-
heat zone, temperatures should be checked on the actual product in the
area where the problem is seen, as component size and placement can affect
the temperature reached.
• Solder balling/beading – There are many possible causes, but one related
to the thermal profile is insufficient flux activation. In this case, the pre-heat
temperature needs to be raised to increase paste activation in line with the
manufacturer's recommendations.
• Component cracking – The most likely cause is too rapid a temperature
change while moving from the pre-heat zone to the wave. After the wave,
cooling is generally not forced, so the temperature gradient here is less
severe.
• Re-melting of top-side SMD joints – If the solder on the top-side
components is re-melted during subsequent wave soldering, the quality of
the SMD solder joints will be compromised. The remedy is to reduce total
heat input to the PCB during soldering, which may involve reducing the
solder temperature and adjusting the pre-heat temperature.
REFLOW TR ACK ER
Wave Solder
35