Oh, gee, ehm, Ryan, mate, close, not sure if enough :
1
Steve's maths ?(sorry Steve, you ARE one of the LEGENDS):
"nearly" 75u" = 1.875um (or close enough);
is NOT in line with ITRI's recommended 1.5um ceiling :
me the coward never had guts to digest even 1um on soldered pads .
I'll give you; with latest pad size trends (smaller); you may creep touch
higher,
but i do know if i'd got totally stoned and placed more than 1umAu on specs,
my fellow in QA would be after my skin .
Besides, Tim 's been just quizzing me where the hell do i squeeze 0.5um from
flush;
whining bitterly all he gets from his fabs is 0.25um tops on flash .
Record i MEASURED on flash was some 0.8um,
so i presume it's my turn in Tim's shoes :
Where would you get saturation's which throws 75u" on Ni ?
Presume only academic maths ?
And the bible talks, i think (?) about 4% , not 3,
but i won't be making scenes about that one
(less is better, almost, hahaha)
And NiAu (0.5umAu average = 20u") costs us less than HASL .
Getting gold ears from all this off hip traffic ;
getting dark here too: Inge : deleted some dozen methaned messages today !
All in good humor Ryan , ok ?, just let's retain the functionality.
Paul
-----Original Message-----
From: Ryan Grant [mailto:[log in to unmask]]
Sent: Thursday, 16 March 2000 10:47
To: [log in to unmask]
Subject: Re: [TN] ??: [TN] Gold Removal
I agree with this. Do the math. If a five mil stencil is used, and the
component leads are NOT gold plated, the board gold thickness can reach
nearly 75 micro inches before the percentage of gold in the joint reaches
the magical number of 3%. Below 3%, gold is not shown to induce
embrittlement. If you are soldering to BGA balls, there is even more Tin to
dilute the gold, so the gold thickness can be even thicker. The reason for
the 5 to 8 micro inches of gold thickness is, that is the MINIMUM needed to
prevent oxidation of the nickel. Thicker gold is more expensive in terms of
processing and material cost, and it is unnecessary, so why do it?
Of course, if I buy a new stereo, and it has a scratch on it, I'll take it
back. Functionality be damned. Rick can do the same with his boards.
Ryan G.
> -----Original Message-----
> From: Timothy Reeves [SMTP:[log in to unmask]]
> Sent: Wednesday, March 15, 2000 3:08 PM
> To: [log in to unmask]
> Subject: Re: [TN] ??: [TN] Gold Removal
>
> Does anyone agree with this? I hope not.
>
> > ----------
> > From: Jonathan A Noquil
> > Sent: Tuesday, March 14, 2000 15:57
> > Subject: Re: ??: [TN] Gold Removal
> >
> > Higher gold thickness does not affect
> > reliability (solderability),
>
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