We constructed our own machine for spotwelding mlb lay-ups prior
to pressing. It works fine for 6 and 8 layers (standard FR4 thin
laminates and prepreg). However, for higher layer counts especially
12 layers we seem often to loose internal layer / layer registration.

Could anyone kindly suggest a set of operating parameters
(temperature / pressure / time etc) to give more reliable welds for
higher layer counts. Pressed thickness about 1.6mm. Panel sizes
are relatively small - 14" x 11" would be typical, with 3 welds on
each long side about 4" apart.

The welder heads have a round flat point 10mm diameter and
existing settings are as follows:
Air pressure on the 16mm dia. welder cylinders is 5.5 bar, head
temperatures are controlled at 280C and weld timer set at 90 sec.

Any other input on this subject will also be welcome.

Thanks,

Mike Holst


Mike Holst.
TraX Interconnect (Pty) Ltd
Tel:(++27 21)712 5011
Fax:(++27 21)712 5798
Cape Town
South Africa

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