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December 2004

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From:
Joyce Koo <[log in to unmask]>
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Date:
Mon, 6 Dec 2004 15:02:26 -0500
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Steve,
"I envision that we will be building tin/lead products for quite a few years
yet. Military minds don't change easily. Besides, there are exemptions for
defense related electronics"
if you follow Mike's advice, you will do no wrong ;-).
As for the mil-mind, it is driven by all the obsolesces parts from
commercial supply.  The few years back, few of the chip supplies cancel many
of their part numbers due to either (a) change to large wafer format, or (b)
limited demand = few thousand aircrafts vs. million of commercial
electronics.  That leave the assembly producer with little choice: (a)
re-spin the whole board with new "hi-rel commercial device with up-grating",
normally you need re-qual of the assembly, or (b) do a life time buy of the
parts and stored in N2 or any way you know how to keep the aircraft going
(life time of the mil-aircraft is much longer than the 3-5 years of
commercial electronics).  Most of the so call "life time =last time buying
parts are lead/tin finishing.  (some of them are gold finishing, so you can
store longer and tin them as you required.. those are ASICs, FPGAs, and
microprocessors... large device size, so you do not have to worry too much
about rad-hardening).  most of the assemblies are try to keep the parts list
compatible to each other, so you can buy "large qty", the qty still very
very small compare to the commercial lot.
If you start introduce leadfree, look like you will have to re-spin the
board and re-qual at assembly level, if not at system level (I am sure those
are new generation of devices, that is possibly sub-micron metallization for
VLSI, if you are lucky... otherwise, you are dealing with ULSI. if it is
really state of the art generation devices.  As for new design, it should
not be an issue.  But the device selection will be limited at current level
(after few years, it may be different).  You are caught at rock and hard
places...
                                    jk my 1.66 cents

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Monday, December 06, 2004 2:02 PM
To: [log in to unmask]
Subject: Re: [TN] Lead-free, and not lead-free...


Hi Ryan!

Unfortunately, this isn't going to be a transitional thing for me, at least
in the near future anyway. We're a contract assembly company that builds
things for most of the the major DoD contractors, and most of them have told
me informally that they aren't even thinking about lead-free. Some have
actually put it into writing. I've pasted a few paragraphs as an example
that was sent to us recently below (I've blanked out the company name:


"At present, (Blank) will continue to order and assemble electronic products
using tin-lead solder. There are currently no (Blank)customer contracts
requiring transition to lead-free solders.

There are, however, (Blank) customer contract requirements for (Blank) to
continue using lead-based solders. These requirements are currently driven
by a lack of community acceptance of reliability and design data to safely
transition to lead-free solders.

We are also concerned about our ability to guarantee the life of products,
and our lack of process controls within (Blank)to manufacture with lead-free
components.

If there is a change in position, (Blank) will notify our suppliers of any
new requirements. Presently, (Blank) is requesting that all suppliers
provide lead-based electrical components and assemblies to (Blank) on all
orders.

(Blank)is monitoring industry work/study group efforts involved in lead-free
solder transition, and while much still needs to be done, we are also
establishing an internal program to evaluate transitioning to lead-free
electronic assemblies, if and when that time comes."


So, I have that stance from existing customers, and have just learned that
we are pursuing business with a company that will have their products
marketed in the EU, and must comply with WEEE and RoHS. So I find myself in
quite a "pickle", as it were...

I envision that we will be building tin/lead products for quite a few years
yet. Military minds don't change easily. Besides, there are exemptions for
defense related electronics.

But if we're going to be build lead-free stuff along with tin/lead stuff,
I'm inclined to agree with Mike Fenner and set-up completely separate areas
with an impenetrable wall between them   ;^)

-Steve Gregory-



Hi Steve,

We're doing it no sweat! :)  O.K., just kidding.  Actually, it hasn't been
too bad, we require our solder paste suppliers to visually mark their tubes
with a "green" color so they aren't easily mixed.

(Snip...)

That would be easier to replace the eventually contaminated pot and keep
pure.  Ideally, you would convert all wave solder machines to lead-free,
assuming all your leaded customers agree to the change.  Then the only risk
is production operators using the wrong solder paste.

Good luck on the conversion.

Ryan Grant

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Saturday, December 04, 2004 6:21 PM
To: [log in to unmask]
Subject: [TN] Lead-free, and not lead-free...


Hi All!

I've got a problem that I've been worrying about all weekend. It may come to
pass that we will be building both lead-free, and standard 63/37
stuff...whoa is me.

I'm interested in stories from those that have done that...what the hell did
you do?

Is this something that can be done? It probably can, but me, being the
pessimistic sort, thinks that you're just asking for trouble when you try to
mix the two...

-Steve Gregory

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