Louis,

Microsectioning should not smear the solder mask to an unreadable
condition...if cured properly. The epoxy mask is durable enough to withstand
the sanding and polishing.

Depending upon the thickness of the mask, trapezoid should not really
present a great issue until you get over 1.5 mils I would think, but would
you really need that much mask on anything?

What are the dam widths you are trying to achieve/control? What is your
current process for solder mask application?

You can create solder mask artwork lines with the varying widths and just
mount them as you would any other cross-section, try to find a way to
include tooling holes for the microsection pins, I would try not to use
those plastic clips to align the coupon as they would not ensure true
perpendicular mounts for viewing thus skewing your readings.

Franklin



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
Sent: Friday, March 07, 2008 5:25 PM
To: [log in to unmask]
Subject: [TN] LPI solder resist thickness

Technetters, I'm planning a designed experiment to find a way to control
dimensions of solder dams between surface mount pads. I am not sure of a
good way to measure dam dimensions, however. My concern is cross section may
smear the resist and make any microscopic measurements suspect.

I suspect looking at the resist on a PC board from the top would give a
width measurement, but I would like to measure thickness as well and see how
trapezoidal is the dam profile.

In the IPC test methods manual I did not find any recipe.

Thanks for any comments or guidance.

Louis Hart
Compunetics
Monroeville, PA   USA
[log in to unmask]<mailto:[log in to unmask]>
412-858-1272

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------


-- 
No virus found in this incoming message.
Checked by AVG Free Edition. 
Version: 7.5.516 / Virus Database: 269.21.6/1316 - Release Date: 06/03/2008
18:58

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------