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Wave Soldering Defects - Lifted Component
Lifted components can occur during wave soldering
for a number of reasons. In the case of Figure 1, the part lifted
due to the thermal demand on the leads. Simply by increasing the
immersion time in the wave eliminated the problem. On lambda style
waves it is possible to increase the contact time by adjusting
the back wave section which eliminates the need to slow down the
conveyor. Slowing down the process does not go down well with production
managers. Generally components lift due to: Incorrect lead length
causing the leads to hit the solder bath and lift during entry
to the wave. Flexure of the board which is commonly seen on large
connectors, IC sockets or large IC packages. Basically the board
flexes and the component remains still. Light components are lifted
by the turbulent wave used for surface mount applications. Components
with either different thermal demands or different lead solderability
can also cause the lifting seen during wave contact. Although not
associated with the wave, vacuum formed shrinkwrap may cause lifting
during wave contact. The shrinkwrap is some times used to hold
components on the surface of the board for lead cutting. It can
be pulled under the leads which causes components to lift during
wave contact.
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| Figure 1: Increasing the immersion time in the wave
stopped this problem from occurring. |
In the case of Figure 2, the part was not inserted correctly
prior to entering the soldering process. It is uncommon for IC packages of
this size to lift during wave contact. Generally components lift due to:
Incorrect lead length causing the leads to hit the solder bath and lift during
entry to the wave. Flexure of the board which is commonly seen on large connectors,
IC sockets or large IC packages. Basically the board flexes and the component
remains still. Light components are lifted by the turbulent wave used for
surface mount applications. Components with either different thermal demands
or different lead materials. If a lead is slow to wet due to the thermal
demand of the component it can lift in the plated through hole and not sit
back on to the surface of the board.
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| Figure 2: This defect originated in the assembly process,
when the part was inserted incorrectly. |
Wave Soldering Defects:
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Lifted Component | |
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