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| Reply To: | TechNet E-Mail Forum. |
| Date: | Tue, 14 Jan 2003 17:33:52 +0800 |
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Marie,
Are your boards to be conformally coated? If you're worried about exposed
copper, you could try filling the holes with dilute conformal coating -
though you will probably have to put the boards in a vacuum oven to pull
the air out of the holes and allow the coating to penetrate and coat the
walls of the holes.
Peter
ME Magnin <[log in to unmask]> 14/01/2003 04:02 PM
Sent by: TechNet <[log in to unmask]>
Please respond to me.magnin
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] voids in gold plated holes
Thanks for this answer and all the others
I was not sure, when reading IPC A600 3.3.9, that it was talking about
copper voids or all plating voids. I understand now that the last is the
correct understanding.
I can see exposed red copper in these voids, I suppose there has been a
problem during nickel plating, thus consequently gold is missing too.
The number of voids is close to the acceptance limits, depending on the
standard I base on (IPC or PERFAG).
But my major concern is that the boards are finished now, and I am not sure
I can deliver them like this : bare copper is still exposed because I have
had poor vertical fill (we use a no-clean solder flux).
ME Magnin
FIRSTEC SA
Rue du Grand Pr¨¦ 70
CH 1211 Gen¨¨ve 2
T¨¦l. : +41(0)22 918 36 85
Fax : +41(0)22 918 36 93
mailto:[log in to unmask]
http://www.firstec.ch
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of [log in to unmask]
Sent: lundi, 13. janvier 2003 20:58
To: [log in to unmask]
Subject: Re: [TN] voids in gold plated holes
Marie
If you look in IPC-6012A, para 3.3.3 There is a table 3.3 that has the
requirements for Finish Coating. Then depending upon which class your
product has been built to meet, you can see the requirements. Class 2
says "Three voids allowed per hole in not more than 5% of the holes" for
example.
Bare copper is always a reliability concern - especially if it is in
contact with gold. Remember that the nickel is put on to prevent the gold
and copper from reacting.
Susan Mansilla
Robisan Lab ---------------------------------------------------
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