Hi all,

We have a minor problem at wave soldering shields on 8-layer FR-4.
The problem is that we need a very long dwell time (6-8secs) to get the
solder to wet all around the shield, it's very critical because it has
to be a tight joint. This leads to a high temperature at topside of the
board at soldering, and inside the shields we have SMD-ICs which joints
reach an temperature to about 209 degC. 
But then if i raise the preheating temperature and lower the dwell time,
the shields won't get this tight joint and misses corners and some
long-sides, this cost some to rework.
Some additional info: Seho wave solderer, NO-CLEAN flux, We put some
extra flux around the shield, we use a chip-wave to get better wetting.
Anyone have more ideas?

/Jan Merstrand
Wave Soldering Technician 

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