Happy,
Werner, Doug, yourself and others have made valid points. The material
spec is but one facet; requiring additional definition of requirements,
both design and functional; knowledge of the process and conditions;
useable life; and end-use environment, in determining an acceptable
candidate.
The point I was trying to make is that all the main specifications need
to be more in line with requirement's definitions that will be
meaningful for use as tool data-set in the
selection/qualification/verification of potential Lead-Free laminate
materials. I am quite capable of putting all those additional
requirements in my own documentation, but what's the point. If I believe
it's right, then the Industry should also agree that it is a viable
target. It doesn't mean it's their target, but we should strive for
standardization as much as possible, so we are only left with a minimal
amount of specialization or deviations that reflect our own functional
requirements. This will help the Industry as a whole.
BTW- We have had coupons pass 20 floats/dips and exceed 500 IST cycles,
but would not pass our minimum 350 cycles (actually, would not pass 250
) when pre-conditioned to the 6 IR Reflow profiles at 260 C. This is our
requirement for a high-rel, Aerospace, Lead-Free material qualification.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Happy Holden
Sent: Friday, May 26, 2006 11:24 AM
To: [log in to unmask]
Subject: [spam] Re: [TN] Rohs Weeeeeee board material
Hi Werner,
Actually, this is the lowest cost way to go. Higher costs would be to
put
down a specific brand of laminate or an IPC-4101 slash sheet.
By putting down these two statements, our 6 , 8, 10 & 12 layer boards
are
being built in China with new Asian Lead-Free DiCY materials (Tg=140C)
that cost the same as the traditional DiCY laminates, but now they have
a
Td >350C and can take 10-12X 288C-10 sec solder dips without
delaminating
or cracking the PTHs. We let the fabricator choose the materials he is
most comfortable with, as long as it has the LF assy performance we
need.
These boards, when tested with a 3X- 260C preconditioning, had 700-1000
cycles of 160C IST performance.
So we are pretty pleased with the immersion silver finish and the
resulting LOWER COSTS of these multilayers even when they have to pass
the
LF assembly hurtle.
Happy Holden
Asian Pacific Materials
[log in to unmask]
05/26/2006 01:24 PM
To
[log in to unmask], [log in to unmask]
cc
Subject
Re: [TN] Rohs Weeeeeee board material
Happy,
That is not a bad way to go--expensive though.
Werner
-----Original Message-----
From: Happy Holden <[log in to unmask]>
To: [log in to unmask]
Sent: Fri, 26 May 2006 12:32:52 -0400
Subject: Re: [TN] Rohs Weeeeeee board material
Hi,
That's why we tell all our clients now to adjust their board blueprint
MFG
NOTES with the following additional statements:
1. That the finished multilayer must withstand (A)The LF assembly
process
description including a. Peak Temp b. Time at Peak Temp c Total
time above 250C on heating and cooling d. Number of Cycles of
a.+b.+c.
and (B) If repair and rework is going to be performed and what
those
Time & Temp will be.
2. That the finished multilayer must withstand 3 cycles of a 288C-10
sec.
solder-dip without delamination or hole cracking, measures and checked
in
(a) Ground-plane area AND (b) In the BGA area before the
board
is shipped.
Happy Holden
Asian Pacific Materials
"Stadem, Richard D." <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
05/26/2006 11:56 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
"Stadem, Richard D." <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Rohs Weeeeeee board material
That is the purpose of a thorough process/procedures audit done
periodically to ensure the material received is going to be good.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: Friday, May 26, 2006 10:50 AM
To: [log in to unmask]
Subject: Re: [TN] Rohs Weeeeeee board material
Hi,
I guess we have a good idea now of the difficulties in specifying and
manufacturing lead-free capable PCBs. The next question that comes to my
mind is how are we going to assess if the PCBs that are well speced are
what we expect?
I mean, the spec can be OK, whether perfect IPC-4010 slash sheets are
developed, or STII is implanted. But the manufacturer might still use
expired prepregs, they can have lamination problems, and so on.
What tests shall a contract manufacturer or OEM with no in-house testing
capability impose, in order to have the confidence that they receive
what they specified?
Thanks,
Ioan
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