Brad,

The boards are manufactured to BS and IPC recommendations by a high volume
international supplier if there are any problems with the plating, ( of
which there is no evidence and which I doubt there are), then its not our
problem.

As for the latest on the actual problem - board warping to well within IPC
recomendations but outside of what we'd like, it seems that the latest
boards have even less of a problem.

Its not gone away, and we are still working on a better resolution, but for
now we've decided to just run with them and see what the best and worst look
like.

Thanks for all your help,


Jason.


-----Original Message-----
From: Brad Velander [mailto:[EMAIL PROTECTED]]
Sent: 11 April 2002 16:41
To: 'Protel EDA Forum'
Subject: Re: [PEDA] WANTED: PCB Expert (Off Topic)


Jason,
        aside from your problems with warp and twist, there are other
possible problems lurking if you do not know the actual thickness of your
Nickel/Gold plating. There are a myriad of complicated
electro/chemical/physics related problems which can occur with Nickel Gold
plating, the most common of which is solder joint embrittlement.
        SN/PB/AU Solder joint embrittlement can cause solder joint failures
in field units which are a devil to find because they will break connections
during thermal or stress cycles and be fine other times. In conjunction with
your warping, your design would be a prime candidate for these failures. In
the extreme cases I have been told of boards having significant numbers of
their components drop off the boards when the board is manually flexed. On a
typical SMD land pattern design if your Gold is greater then approx. 25 - 30
microinches then you may have embrittlement problems if you do not use
special solder compositions.
        I would suggest that you must find out what the nickel & gold
plating thickness is for your board. Then you could discuss them here with
us and we could give you some more detailed information. In the future you
should specify the gold plating requirements and not rely on luck or a
single fabricators judgement as to what plating thickness your require for
your board.
        One of the best studies which I have found on this issue was
performed by HP. The article was titled "Effect of AU on the Reliability of
Fine Pitch Surface Mount Solder Joints" by Judith Glazer, HP, Palo Alto,
California. It was published in "Proceedings, Surface Mount International
Conference, Aug 25 - 29 (1991), San Jose, CA." It was republished in Circuit
World 18, pg 41-46 1992 and Surface Mount Technology 4, pgs 15 - 28 (1992).

Good luck Jason.

Sincerely,
Brad Velander.

Lead PCB Designer
Norsat International Inc.
Microwave Products
Tel   (604) 292-9089 (direct line)
Fax  (604) 292-9010
email: [EMAIL PROTECTED]
http://www.norsat.com

See us at Booth S8155 at NAB 2002 in Las Vegas April 8 - 11.


> -----Original Message-----
> From: Jason Morgan [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, April 11, 2002 1:10 AM
> To: 'Protel EDA Forum'
> Subject: Re: [PEDA] WANTED: PCB Expert (Off Topic)
> 
> 
> Monitoring - sort of, bit busy for full followup.
> 
> Anyway, I did post a full explanation that the plating would 
> be Cu+Ni+Au, no
> idea on the proportions.
> 
> J.

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