TechNet:

We are currently evaluating the Multiline Multiframe glass frames on a
Colight 1330 exposure unit.

We are seeing loss of contact resulting in reduced spacing and/or bridging
of circuits. Although the exact location of the off contact varies, it
seems to be concentrated in an approximately 3-inch wide band at the front
(closest to the operator) and back of the glass along the length of the panel.

The frame installation has been thoroughly inspected to ensure that the top
glass can close flat against the bottom with no binding or misalignment.

The vacuum pressure has also been inspected and appears to be working fine.

The majority of the image tests have been done using .0025" cores with 1
oz. copper, although the off-contact condition has been seen with a variety
of core thicknesses.

Our dry-film vendor suggested placing .005" shims between the glass around
the perimeter of the panel when imaging the .0025" material, which appeared
to work pretty well (the image quality was much better with no noticeable
off-contact).

However, we were told that the use of shims would be unnecessary with this
system and would prefer not to use them if possible.

If anyone has any suggestions or has had any experience with the Multiline
frames your input would be appreciated.

John Lennox
Process Engineer
EMC

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