Judy:
Your confusion is understandable.
From MIL-G-45204C:
Type designates the purity of the gold (I, II or III). These are 99.7%,
99.0% and 99.9% respectively.
Class designates plating thickness with Class 1 being 0.00005 inch,
minimum. This conflicts with the .000030" callout.
In addition, there are Grades A through D for hardness, A being the
softest.
From QQ-N-290A:
Class 1 is a corrosion protective coating.
Types aren't given, so I have no idea what Type 7 refers to.
Plating is designated by Grades A through G, G being the thinnest at
0.0002" inches.
QQ-N-290 now belongs to the SAE and is known as SAE-AMS-QQ-N-290. It
was transferred pretty much intact.
MIL-G-45204 has been cancelled. The cancellation notice refers you to
AMS 2422 and ASTM B488 as possible replacements. We have adopted ASTM
B488 as our replacement feeling that some of the inspection requirements
of AMS 2422 were overly costly.
As for the plating callout, we generally specify ENIG instead of
electrolytic gold so our gold thickness is considerably less. The
nickel thickness is equivalent. Hopefully, one of the TN gurus can
comment on the brittleness and appearance aspects, but the gold
thickness called out seems high to me.
Rich.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Judy Brown
Sent: Wednesday, May 04, 2005 9:35 AM
To: [log in to unmask]
Subject: Re: [TN] minimum nickel thickness`
What is the standard thickness for electrolytic gold plate on BGA pads?
My customer's print is calling out .000030" minimum per MIL-G-45204 type
C class 1 over nickel plate .000150" per QQ-N-290 class 1 type 7. I have
misplaced my mil specs and do not remember the classes and types. Can
someone translate please? I am thinking that is too much gold for
surface mount soldering. Wouldn't the joint be dull and brittle?
Judy
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of R Sedlak
Sent: Tuesday, May 03, 2005 5:39 PM
To: [log in to unmask]
Subject: Re: [TN] minimum nickel thickness`
Phil:
Are you talking electroless or electrolytic Nickel? I believe
electroless to be MUCH more robust, and less pore prone. I would want
50% more electrolytic than electroless for the same protection, but even
this 50% factor can vary dramatically depending on plating rate.
Other question is this for simply surface mount, or, what other places
will it be done on the PCB? Will the board have tabs, and be inserted
and removed frequently?
So, as in many situations, the best answer probably is, "It depends".
Rudy Sedlak
RD Chemical Company
"Crepeau, Phil (Space Technology)" <[log in to unmask]> wrote:
hi,
forgetting about ipc spec requirements, what is the minimum nickel
plating thickness over copper on a printed wiring board that you would
feel comfortable with as a barrier against copper migration.
thanks,
phil
---------------------------------------------------
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
-----------------------------------------------------
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
---------------------------------------------------
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
-----------------------------------------------------
http://mail.yahoo.com
---------------------------------------------------
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
-----------------------------------------------------
|
