SIR Doug and fellow Techies
I am much obliged for your rapid responses and help - particularly to Jim
Douglas of KAM (or is it CAM?) Circuits here in the UK - he has offered to
strip a couple of coupons and we will run some SIR tests to check out their
condition.
Doug makes an excellent point but I would appreciate his / your views on
using HASL v Bare copper for our coating tests. Yes, I am sorry we will be
running some tests on a new coating material.
First, I do appreciate that the spec (IPC-CC-830) calls up B25A bare copper
so any results may be questioned. However, if you tested with HASLed coupons
would you expect the results to be better or worse? Our experience has shown
that HASL v NiAu has little appreciable difference.
I would surmise that the results we obtain would be / could be considered
"Worst Case".
As to the Gerber files - I have them here already along with the fabrication
spec. - which calls up bare copper! But our order stated HASL aaarrghhh! -
Guess this must go into our ISO 9001 (yeah I know!) "Screw-ups" portfolio -
which is VERY THIN I might point out!!!!
Regards,
Graham Naisbitt
[log in to unmask]
WEB: http://www.concoat.co.uk
CONCOAT Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK
Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>; <[log in to unmask]>
Sent: Friday, February 18, 2000 5:24 PM
Subject: Re: [TN] Removing HASL
> In a message dated 02/18/2000 9:24:56 AM US Eastern Standard Time,
> [log in to unmask] writes:
>
> >
> > I wonder if anyone has any ideas about removing HASL from B25A coupons.
> > Someone here goofed and ordered our test coupons with HASL instead of
bare
> > copper - you can't get the staff you know!
> >
> > So, as it will take some time - and money! - to get these replaced I
> thought
> > I would put this to the experts.
> >
>
> Graham,
> This is one of those Can I - Yes, Should I - No questions. B25A boards
are
> cheap and you will put more money into stripping the tin-lead than you
will
> for new boards. In quantity, these boards only cost $3-4 each (at least
when
> I buy them for our inventory here).
>
> Second, the SIR will be degraded by about half a decade, perhaps more,
> depending on the porosity of the mask and laminate. I presume you are
> looking at qualifying a coating or mask, which is what that board is used
> for. If your mask or coating fails the SIR test, was it a fault in the
> material being qualified or an effect of the stripping? I suggest that
you
> run a few virgin bare copper B25A boards and a few stripped B25A boards
> through a few days of the test environment. If you see no appreciable
> difference between the two, then use what you have. Without this check,
you
> will never know.
>
> I have Gerber files for the B25A if you are interested and can e-mail them
to
> the fabricator of your choice, if you wish. I don't know if you have a
local
> source for these boards, as I do.
>
> Doug Pauls
> CSL
>
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