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December 2004

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Subject:
From:
James Hofer <[log in to unmask]>
Reply To:
James Hofer <[log in to unmask]>
Date:
Mon, 6 Dec 2004 17:23:44 -0800
Content-Type:
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text/plain (194 lines)
We use and are very pleased with LG's lead free materials they do have a
higher Td. Also halogen free material while having a lower Tg have a much
higher Td of about 380c.
Are your other laminates phenolic cured? If so that would explain why you do
not see any difference between your high Tg and lower Tg FR4's.

That's my $.02

James Hofer
Director of Operations
Accurate Circuit Engineering
3019 S. Kilson Dr.
Santa Ana Ca. 92707-4202
714-546-2162 work
714-473-6127 cell
[log in to unmask]
----- Original Message -----
From: "Ryan Grant" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 06, 2004 3:35 PM
Subject: Re: [TN] Lead-free, and not lead-free...


That's a negative.  There are no stinky or discolored laminates in our
reflow ovens.  LG sent a letter stating their FR-4 cores and prepreg can
be used in a lead-free process.  All other suppliers passed on the
request.  However, our own internal testing (hundreds of assembled
boards going through thousands of hours of tempcycle testing on a
regular basis) showed a "what's the big deal?" for the low (and high) Tg
standard regular regular FR-4 laminates (as well as Halogen free
laminates).  Solder joints and components fail long before the laminate,
regardless of the lead-free process.  Granted, our own lead-free process
does not peak at 260C but at 240C, and our finished product is only
0.050" thick or less.

Ryan
-----Original Message-----
From: Bill Decray [mailto:[log in to unmask]]
Sent: Monday, December 06, 2004 11:09 AM
To: 'TechNet E-Mail Forum'; rgrant
Subject: RE: [TN] Lead-free, and not lead-free...


Hello Ryan,
So is it fair to say that all of your PCBs are made with materials that
have a high  Td

Highest Regards

William W. DeCray III
V.P. of Sales and Marketing
Waytec Electronics Corp.
Desk: (434) 237-6391 ext 115
Cell  : (434) 851-6115
Fax  : (434) 237-1324
Web: www.waytec.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ryan Grant
Sent: Monday, December 06, 2004 12:59 PM
To: [log in to unmask]
Subject: Re: [TN] Lead-free, and not lead-free...


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.  (green
because it make you sick that lead-free is touted as environmentally
friendly).  At first the lead-free solder paste was called out on the
BOM.  Now lead-free solder is the rule and leaded solder paste is called
out on the BOM.  Initially, this meant a slightly higher solder paste
scrap, but that has subsided as used solderpaste is transferred to the
next "like solderpaste" build.

You can use lead-free, non-BGA components on all leaded BOM's, so our
component suppliers were driven hard to supply only lead-free.  We used
up all our leaded component inventory and replaced it with lead-free
before making the full switch.  Of course, there are some stragglers,
but they are controlled by the BOM.  You "could" maintain both lead-free
and leaded components in inventory and manage them through the BOM, but
that means duplicating components.  For about a year, we had that
unfortunate situation while the conversion took place.  It is best to
convert to backward compatible components, i.e. Lead-free whenever
possible to prevent the component duplication.

We've only had one incident over two years where work instruction were
not followed and leaded solder paste was used instead of lead-free with
a lead-free reflow profile.  Our reliability testing has shown the
higher reflow temperature does not cause any loss in reliability for our
product; but just to be safe, we redirected that build to specific
low-grade consumer markets.  As an OEM, we have that luxury.

Our process is fully SMT and no-clean, so we get off a little easier
than you.  However, I've never heard of a shop allowing production
operators to add solder to the pot.  This is typically relegated to
Equipment Support technicians, so unless your shop is different, the
number of employees "accidentally" contaminating the pot with lead is
minimal and easier to control.

Accidentally contaminating a lead-free build by building on a leaded
wave is a greater concern.  We have a particular line that was not
capable of lead-free so our planning department had to manage what
builds went on what line.  But again, production planning is a very
limited group, thus no mistakes.

Assuming a lead-free build was contaminated with lead from the wave, you
could recover the product using a manual lead-free rework fountain. 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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