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July 2000

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Subject:
From:
Paul Klasek <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 1 Aug 2000 08:57:27 +1000
Content-Type:
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I like Gary's,
apart from that, 
considering the heat loss and gold's relative resistance to wetting,
it will help you to fill the barrel .
True, with foam wicking heaps of flux up,
you should be able to make it without tin, if you'd have less than 1um Au:
I wouldn' even push it to 2um, on connectors.

With heavy plate as you imagine you fracture the intermetalic,
often magnified by the dry character of uneven heat.
Agree, does not look like a big deal ,
but con's caught me up few times .
Sounds like the ALWAYS has had a very REAL reason, down in obscure past.
But Au specs DID change a lot last decade :

Your 30 of millionths of an inch convert according to my maths to 
some 0.76 micrometre, unless I messed it up as usual;
than Gary's quote would not apply;
than the short answer would be 

NOT REALLY, Steve, give it a shot

paul


-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Tuesday, 1 August 2000 6:20
To: [log in to unmask]
Subject: [TN] Pre-tinning...


Hi ya'll!

We've got a board here that we're going to be assembling that is
transferring 
from one of our other plants. They sent us a "Gold Board" so that we could 
look at it and have it in front of us to help when we write the work 
instructions.

It's a all PTH board and quite large. All along one edge of the board there 
are these right-angle headers. They're from FCI/Berg and gold plated. 

I noticed on the "Gold Board" it looked like they had been pre-tinned. I 
hadn't ever seen that before. I went back to the stockroom and checked the 
parts we had back there, and the whole header was gold plated. I called our 
sister plant and asked if they pre-tinned the headers before installing
them. 
They said they did. I asked is this something the customer requested and
they 
said no, but that it was something you ALWAYS did when you are dealing with 
gold plated parts...

I went to FCI's web page to see how much gold was plated on them, but I 
couldn't find the exact part there (they're still updating the web page with

part numbers since they bought Berg). But the gold plating thickness that I 
read on the page with similar parts was either 30-µin., or 15-µin...that 
doesn't seem to me like there's enough there to worry about gold 
embrittlement, especially with a PTH joint...

Do we REALLY need to pre-tin these things?

Thanks!

-Steve Gregory-

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