I don't think it matters where the Au is...
If it is in the solder interface, it will always be a problem with the
smaller joints currently being formed...Add to the fact that the joints
end up as both electrical and mechanical elements in PCAs...
Paul Edwards
Process/Quality Engineering
[log in to unmask]
Tel: 408-433-4700
FAX: 408-433-9988
Surface Art Engineering
81Bonaventura Dr.
San Jose, CA 95134
DUNS: 944740570
CAGE/NCAGE: 1XZ48
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, May 14, 2007 10:52 AM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors
What bogert was referring to, I think, was finished leads of components
bearing gold, not a board finish.
ENIG is exempted from the requirement to show proof of no embrittlement.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Monday, May 14, 2007 12:15 PM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors
I would think it a bit premature to mention it as the finish of choice -
period.
The common form of ENIG has very brittle intermetallics (Ni/Sn). I would
opt for immersion silver as a safer alternate particularly for mobile
(throw it
around) applications.
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Monday, May 14, 2007 9:34 AM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors
As the RoHS solder joints get smaller and become more interface
sensitive (i.e. QFNs), the volume ratio of available Au to Sn is
increasing....It may be a bit premature to bless Au as the RoHS finish
of choice...
Paul Edwards
Process/Quality Engineering
[log in to unmask]
Tel: 408-433-4700
FAX: 408-433-9988
Surface Art Engineering
81Bonaventura Dr.
San Jose, CA 95134
DUNS: 944740570
CAGE/NCAGE: 1XZ48
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of - bogert
Sent: Sunday, May 13, 2007 9:03 AM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors
It is true that J-STD-001 currently requires gold to be removed from all
SMT components. However, I am not sure we want to continue with this
requirement in J-STD-001. Since the advent of RoHS, and even before
this, folks have manufactured millions of parts with gold finish. As
long as the quantity of gold in the completed solder connection is not
causing gold embrittlement, I think we need to revise the requirements.
I am making a comment to our Task group who is currently developing
revision E of the standard.
>From: "Dehoyos, Ramon" <[log in to unmask]>
>Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
"Dehoyos,
>Ramon" <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: [TN] SMT connectors
>Date: Tue, 8 May 2007 08:54:11 -0400
>
>
> Steve:
> Yes, gold must be removed from SMT parts regardless. In a static
>solder pot, it is very difficult, but fine pitch parts can be replated
>by a miniwave with a N2 blanket. There is no need to dip it twice
>neither due to the fact that the melt is moving. It works very well
and
>it is done fast and no bridging.
> Regards,
> Ramon
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
>Sent: Monday, May 07, 2007 3:15 PM
>To: [log in to unmask]
>Subject: Re: [TN] SMT connectors
>
>Hi Phil!
>
>We don't make choices regarding SMT connectors, our customers do, and I
>can tell you I've seen a lot of different styles.
>
>There's one thing about them that I've seen lately that I really don't
>like, and it's mainly the SMT connectors that come from Samtec. Lately,
>they been coming out with some high-density fine pitch designs that are
>flash gold plated (RoHS compliant!), and that's the ONLY WAY you can
get
>them now. Flash gold is the RoHS finish of choice it seems for Samtec.
>But now to comply with the J-STD, you must remove gold no matter what
>the thickness on the solderable surfaces of SMT parts...right?
>
>I've sent some samples of QSE and QTE series connectors to a company to
>see if they can tin and remove the gold them for me. I hope they can,
>but they may not be able to without a lot of bridging because of the
>design of the connector. http://www.samtec.com/ftppub/pdf/QTE.PDF I
just
>know I don't want to try and do it myself.
>
>I think this connector was a bad choice as far as reliability is
>concerned (but I'm not the customer). These connectors are being used
to
>interconnect and stack with other boards, and there's no mechanical
>support built into the connector other than the grounding strip that
>runs down the middle of the connector. Plus we're putting down the big,
>tall -07 lead style connectors (they're almost 1-inch tall!)
>
>So really look at the connectors carefully. There's a lot out there and
>they may seem like the perfect answer to eliminate a process step...but
>be careful!
>
>-Steve Gregory-
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
>Sent: Monday, May 07, 2007 11:05 AM
>To: [log in to unmask]
>Subject: [TN] SMT connectors
>
>Hi Techies,
>
>What choices have you made regarding SMT connectors?
>
>We are designing some new SMT boards and could put SMT connectors on to
>reduce or eliminate a wave or hand solder step. I am looking at
>D-subminiature connectors and 0.100 on center ribbon connectors. Each
>are available in SMT. My concern is that the SMT is less durable in a
>high usage or high vibration/shock environment. Saving a step isn't
>worth it if it created more long term failures.
>
>Thanks in advance.
>
>Phil
>
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