Vicor Micro Family of DC-DC Converter - Manual (Page 66)

Design Guide & Applications Manual
For Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies
Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com
Page 65 of 88
Apps. Eng. 800 927.9474 800 735.6200
13. Recommended Soldering Methods, Lead Free Pins (RoHS)
Index of Common Soldering defects.
1. Solder Bridge. A short circuit between two electrically
inadvertently forming a “bridge” or connection between
the two points.
Recommended Solution. Use a smaller soldering tip,
or hold the tip at a different angle when soldering, so
as to contact only one pad at a time.
2. Cold Solder. An incomplete or poor connection
caused by either the barrel or the pin not being
heated to the flow temperature of solder. A cold
solder joint will typically exhibit a convex meniscus
with possibly a dark spot around the barrel or pad.
Also, a cold solder joint will not be shiny, but will
typically have a “dirty” appearance.
CAUTION: A cold solder joint is not necessarily
an open connection electrically, and cannot be
diagnosed by a simple continuity check. A cold
solder joint is frequently an electrically inter-
mittent connection and is best diagnosed by
way of visual inspection. A cold solder joint will
likely become electrically open following a period
of temperature cycling.
Recommended Solution. Increase soldering iron
temperature, soldering time, or use a soldering iron
with a higher output wattage if hand soldering. If
wave soldering, lower conveyor speed or increase
preheat temperature.
3. PC Board Damage. An intermittent or poor connection
caused by damage to a trace, pad, or barrel. A damaged
pad is best identified by a burn mark on the PCB,
or a trace pad that moves when prodded with a
mechanical object.
Recommended Solution. Lower the soldering iron
temperature or the soldering time. If damage persists,
use a lower power iron, or consult with the manufacturer
of the PCB for recommended soldering guidelines.
4. De-wetting. The solder initially appears to wet but
then pulls back to expose the pad surface. More
common in wave-soldering.
Recommended Solution. Make sure the PCB is clean
prior to soldering.
5. Dry Joint. The solder has a dull gray appearance as
opposed to a bright silver surface. The solder joint may
have a mottled look as well, with jagged ridges. It is
caused by the solder joint moving before it has
completely cooled.
Recommended Solution. Immobilize the module
with respect to the PCB to ensure that the solder joint
cools properly.
6. Icicles. Jagged or conical extensions from solder fillet.
These are caused by soldering with the temperature too
low, or soldering to a highly heat absorbent surface.
Recommended Solution. Increase the soldering
temperature, but not outside the recommended limits.
If necessary, use a higher power soldering iron.
7. Pinholes. Small or large holes in surface of solder
joint, most commonly occurring in wave solder systems.
Recommended Solution. Increase preheat or
topside heater temperature, but not outside the
recommended limits.