TECHNET Archives

January 2003

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:
"Barmuta, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 29 Jan 2003 14:10:43 -0800
Content-Type:
text/plain
Parts/Attachments:
text/plain (69 lines)
Tom: Are these boards gold plated? If so, I would guess the color change was
caused by cobalt.  Some gold plating baths have cobalt as a component of
their chemical makeup. If the silk screen ink is porous or not fully
cured/polymerized the cobalt can be absorbed into the surface of the ink
during plating. When heated (reflowed) it turns purple.
Old-timers in the bare board business will remember this same effect "Purple
Plague" causing the laminate to turn purple usually after fusing.
We could make it go away by oxidizing it using a strong UV (200
watt/inch)light source.

                                                                Regards


Mike Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076

-----Original Message-----
From: Tom Parkinson - Quality System Manager - WinTronics, Inc.
[mailto:[log in to unmask]]
Sent: Wednesday, January 29, 2003 12:29 PM
To: [log in to unmask]
Subject: [TN] Silk Screen Goes Purple


Purple?!

We just finished running a batch of 15 PCBs through reflow and noticed
on 2 of them, the silk screen changed from white to a very even shade of
semi-dark purple.  The change was uniform across the entire board.  The
boards were not the first or last ones through the reflow, no changes
were made to the profile.

Contacted the PCB house and they said they have never seen anything like
it.

Any ideas??

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

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