Hi Ken: We do a lot of all gold PCA's which are electroplated. I assume you
are planning on using the same type of finish. We specify 10-20u" with 15u"
nominal and have not had any embattlement problems.
If you are using the gold for key pads or contacts etc you probably don't
want to go any thinner. If we are using the gold for rotary switches or a
high abrasion area we do a double gold plate   adding an additional 15-20u"
of overplate only to those selective no soldered areas. But it is more
expensive and I would not recommend it if you don't need it.

The only word of caution I would give you; if you are going with all gold
electroplate be aware of the variation in plating thickness across the panel
due to current density differences. The are a variety of causes that I won't
get into but make sure you check plating thickness across the panel and
especially in high current density areas. Poorly controlled electroplating
can put you over your max spec limit. Some fabricators have problems
controlling deposit thickness.
Also don't forget to specify the electroplated a minimum thickness of 100u"
of Ni under the gold.

                                                                Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076


-----Original Message-----
From: Bloomquist, Ken [mailto:[log in to unmask]]
Sent: Wednesday, October 27, 2004 10:14 AM
To: [log in to unmask]
Subject: Re: [TN] Gold Board


Thank you everyone! I think from all your replies I have the answer. Our
application would work with plating down to 15 microinches. That is well
below the 30 that several of you have mentioned. With some additional
testing at say 20 microinches I think we'll be OK.

Thanks again,

KennyB

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Valerie St.Cyr
Sent: Wednesday, October 27, 2004 8:38 AM
To: [log in to unmask]
Subject: Re: [TN] Gold Board


Ken,

Gold embrittlement is more a concern for fine pitch surface mount joints
where the percentage volume of gold grows as the absolute volume of paste
decreases. That being said, the gold thickness should still be kept low.
The pads which need to be gold will drive the final decision; why are
those pads gold and what does that mean for their necessary gold
thickness? If they are "thick" electrolytic gold, over 30 microinches,
then typically the fabricator would make the board in 2 gold passes: one
pass to put on a light sacrificial thickness of gold; then they would mask
off the whole board except for the pads of interest; then another pass in
gold to plate up those pads thicker - to 30 or 40 or 50 microinches
(whatever is called for). This 2 pass processing adds cost. If the gold
pads can be 25 microinches or less, then they can just gold plate the
whole board in one pass.

For all of this I am assuming that this is electrolytic gold over
electrolytic nickel.

Valerie

---------------------------------------------------
Technet Mail List provided as a 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/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 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------