Richard,
        Could it be the change of seasons?  I believe  humidity and
temperature have an affect on several processes from the weaving operation, to
impregnation at the laminator, to stack-up, and press.  But, I don't have any
hard data to prove it.  Maybe the gremlin is Mother Nature in disguise.

Glenn Pelkey
Quality/Reliability Engineer


Richard MacCutcheon <[log in to unmask]> Wrote:
|
| We seem to have developed a gremlin in our registration
| dept.
| A very large portion of scrap is attributed to NO Annular
| Ring (<.002").
|
| Over 90% of our product is 8-layer GIL with 2 and 7 as
| ground planes.
| Cores are .005 constructed of 1-106 and 1-2313.  Prepreg
| is 2313.
|
| Layer to layer misregistration is around .005" on average.
|  Artwork pad
| sizes are .022" over the max acceptable hole size.
| Tooling seems to be as
| tight as ever but in the last few weeks we have had an
| inordinate amount of
| scrap due to NO Annular Ring.
|
| What is the best systematic approach to take in
| identifying the problem(s)?
|
| Thanks for your time.
|
| Richard MacCutcheon
|