TECHNET Archives

August 2007

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Condense Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Sender:
X-To:
Date:
Tue, 28 Aug 2007 16:28:22 EDT
Reply-To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Subject:
MIME-Version:
1.0
Content-Transfer-Encoding:
7bit
Content-Type:
text/plain; charset="US-ASCII"
From:
Dennis Fritz <[log in to unmask]>
Parts/Attachments:
text/plain (46 lines)
 
In a message dated 8/28/2007 3:23:54 P.M. Eastern Daylight Time,  
[log in to unmask] writes:

As  in
the case of Paul's response below, this would also probably cause  the
pad adhesive to weaken.



Please remember that there is no "pad adhesive" on rigid boards.  That  was 
the old construction on flex, and now a lot of flex is  "adhesiveless".  The 
bond of copper pads/traces to the rest of the board is  physical - foil 
roughened on one side at the time  of manufacture.  And now, with the emphasis on high 
speed signal  traces and "low profile foils" - there isn't much "tooth" left 
for the curing  epoxy to physically attach to.  Take it easy with heated 
irons.  
 
My votes in order are:
1. laser ablation - can be run off the CAD program for trace areas and only  
focused on copper. 
2. abrasive removal - less selective than laser, but should not damage  epoxy 
of board
3. heat of any sort
4. chemical - remember epoxy is almost always one of the polymers in the  
mask. What is the board made of - epoxy!!.  It is a very tight chemical  
tightrope to chemically attack mask without some attack on the board epoxy. 
 
Denny Fritz
MacDermid



************************************** Get a sneak peek of the all-new AOL at 
http://discover.aol.com/memed/aolcom30tour

---------------------------------------------------
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
-----------------------------------------------------

ATOM RSS1 RSS2