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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Thu, 17 May 2007 12:21:31 -0500
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text/plain (376 lines)
: <[log in to unmask]>

: <[log in to unmask]>
: <[log in to unmask]>

Yep, I got a quote from Samtec and the price is a couple of bucks more
per connector with tin/lead leads instead of gold. After doing the math
to meet the minimum 100,000 contacts, we would use that amount of
connectors fairly easily in the number of assemblies we're planning to
build. I hope that we won't experience the problems that you've had
though...

I got the samples of the gold plated connectors back from the tinning
house that tried to remove the gold for me, and if you remember my
previous email, they turned the job down. No matter what they did, they
couldn't avoid the solder bridges because of the way the connector is
made. If you don't want gold plated leads, you have to start from
scratch with the leads being tin/lead before the connector is assembled.
I've got some pictures of what the connector looks like after their
attempt at removing the gold:

http://www.stevezeva.homestead.com/files/Samtec_Connector.jpg

http://www.stevezeva.homestead.com/files/Samtec_Bridges.jpg

Oh I suppose you could wick the bridges from the connector leads if you
wanted to, but who in their right mind is going to do that?

-Steve Gregory-



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Scott Lefebvre
Sent: Tuesday, May 15, 2007 2:04 PM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors

Yes they will configure the connector the way you want it but getting it
isn't as easy as it would seem.  

I order parts several months ago requesting Mat tin solder tails instead
of gold. I got the part number from Samtec and it was also in their data
sheet.  The part would come in with the correct part number on the tube
but the physical part was not correct.  After several months of phone
calls and emails we have just now received the correct parts.  This was
not an easy process.

Scott Lefebvre

-----Original Message-----
From: Phil Nutting [mailto:[log in to unmask]]
Sent: Monday, May 14, 2007 11:30 AM
Subject: Re: SMT connectors

Pardon my stupidity, but won't Samtec build you a connector configured
they way you want?

Phil 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, May 14, 2007 1:48 PM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors

Hi Richard!

I understand what you are saying, but I'm seeing more and more SMT
connectors out there (especially from Samtec) that are finishing them
with flash gold that is next to impossible to remove the gold. 

The company that I talked about in my original post gave up
trying....and they really tried. Brought their oxygen analyzer out to
try and get the 02 levels down over the wave they use to remove the gold
at their place, and got it down to 25ppm. The stupid connector still
bridged. Even tried to give it a little physical shock (by tapping it)
immeadiately after the wave to try and knock the bridges loose, but no
joy. They're returning the connectors back to me and rejecting the job.
The problem is the grounding strip the runs down the middle of the
connector.

So I'm stuck...unless I want to try and tin these things by hand and use
some solder wick to remove the bridges. I know that ain't gonna happen.

I wonder if Samtec bothers to read the J-STD when they create these
things? I also wonder if they would guarantee that there won't be any
issues without removing the gold? I might just call them and see what
they say...

-Steve Gregory-

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, May 14, 2007 8:55 AM
To: [log in to unmask]
Subject: Re: [TN] SMT connectors

Bogert,
Some of us to wish to continue with this requirement.
The requirement was put there for a very good reason. I would be very,
very careful when changing it. You will need to qualify any new
parameters fully, to cover every lead/pad configuration that currently
exists by implication. 

If any amount of gold is added to a solder joint, some corresponding
nucleation is going to take place.

I would recommend a Class 1, Class 2, Class 3 type of arrangement, with
Class 3 being the current standard listed in J-STD-001DS (none allowed
in the area to be soldered, period). But I would also recommend a
reference to a test method and a reference to a %-by-volume calculation
method for the Class 1 and Class 2 levels. Too many people are out there
soldering gold parts and then adding a 5 lb weight or some type of shear
test immediately afterward and saying "it did not break, therefore I
have 'subjective proof' of no gold embrittlement issues". 

Ignoring the time variable happens because there is no definition of
what "subjective proof" is.

The Space Addendum (J-STD-001DS) requires all gold be removed in the
area to be soldered. Again, there are good reasons for this. This
portion of the standard should not be taken lightly or changed without
full qualification.
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of - bogert
Sent: Sunday, May 13, 2007 11:03 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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