TECHNET Archives

October 2002

TechNet@IPC.ORG

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

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

Print Reply
Subject:
From:
Adam Seychell <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 15 Oct 2002 20:02:49 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (39 lines)
I am looking at the possibility of making boards with electroplated tin
finish (tin over copper). From  the experiments I've done so far with tin
finished boards there exists a problem with tin slivers after etching. This
same problem agrees with what people have mentioned in a couple of past
posts on IPC TechNet forum regarding tin as the final finish. Etching
undercut is unavoidable and therefore slivers will always be around. I am
interested to know if people are successfully making such boards and if so
what are they doing to minimize this problem.

Some of the ideas are:

1) Follow with a solder reflow stage to remove the slivers

2) tin plate at minimal thickness so the slivers are too week to be
supported and fall off during normal etching and rinsing cycles. Practical
minimum plating thickness is about 1 um (40 micro inches). This idea doesn't
sound very good going by what I hear about copper/tin migration and the poor
solderability that can result over a period of time.

3) go over each board with a nylon brush and hope that no problematic
slivers remain to cause shorts sometime down the track.


I am just starting out with PCB fabrication and trying to learn more about
the industry. Please excuse me for asking such basic questions.

Adam Seychell

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2