Ed - Sorry to come in late on this discussion on V-Scoring. One additional
factor that was not mentioned by a few other comments I scanned is the depth
and alignment of the V-grooves. I agree with the others on chip caps as the
main problem that I have found, but the component's distance can vary based
on the remaining web thickness (remaining FR4 material after scoring). A
client of mine is currently assembling approximately 25,000 PC Boards per
month and we have chip caps less than 0.100" from the V-Score's centerline.
As long as the fabricator controls the web thickness to our requirements, we
do not have any chip cap cracking problems. Also note that the Z5U caps are
more sensitive to this type of cracking then say X7R's. Some suggestions for
you to consider: Make sure your fabricator does scoring on both sides
simultaneously (no flip scoring) and thirty-degree cutters should be
preferred. Finally, I would suggest you separate the boards prior to ICT,
but testing many times will not find cracked chip caps. Until you fully
define your scoring requirements, a detailed visual inspection of the
components near the scoring is also strongly recommended. Please feel free
to contact me offline.

Ed Valentine
Electronics Manufacturing Solutions
8612 Mourning Dove Road, Raleigh, NC 27615
Phone: (919) 270-5145, Fax: (919) 847-9971
Email: [log in to unmask]
Website: http://www.ems-consulting.com

----- Original Message -----
From: Ed Holton <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 01, 2000 11:01 AM
Subject: [TN] V-Score--stress


> We have recently started using boards with V-score for the panelization
and
> we have a debate raging here.  There is a concern about separating the
> boards before versus after the incircuit test and whether there is the
> possibility that there is imparted stress to the board that could create a
> failure mechanism that might have been caught at the ICT and not at the
> functional test, thus the requirement to singulate before versus after
ICT.
> I have read various articles, but am wondering what people have found in
> the real world.
>
> Thanks
>
> Ed Holton
> Manufacturing Engineer and Group Leader
> Hella Electronics
> Telephone (734) 414-0944
> Fax (734) 414-0941
>
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