Hi Karl,
No argument about the importance of overall board
thickness and worst case PTH aspect ratio; but then you also need to consider plating thickness and ductility, resin content, moisture content, degree of cure of prepreg layers, use of non-functional lands, etc. ad infinitum.
That is NOT what STII is all about, it is NOT a substitute for a proper DfR nor can it take the place of proper qualification. It is meant to be a simple pre-selection tool before wasting any efforts on clearly inadequate materials.
Ianfox hit it just right in his e-mail on the subject.
Werner
-----Original Message-----
From: Karl Sauter <[log in to unmask]>
To: Werner engelmaier <[log in to unmask]>
Sent: Thu, 4 Dec 2008 3:07 pm
Subject: Re: [LF] Fwd: Draft for IPC-4101C
Werner,
In our experience, the STII formula should include overall board
thickness and worst case PTH aspect ratio as factors in order to be
sufficiently useful.? Otherwise it's benefits are more limited, not
enough to justify the added complexity of having STII in industry
standards.
Regards,
Karl Sauter
Werner engelmaier wrote, On 12/04/08 11:14:
Hi Karl,
The whole purpose of the
STII concept was to be simple to the point of being simplistic---it
certainly is better than an arbitrary Keyword: "Lead-free compatible."
And certainly, it was never intended to take the place of qualification
runs.
If anybody placed confidence an just the STII-value, that clearly is a
misuse of its purpose.
Werner
-----Original Message-----
From: Karl Sauter <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 4 Dec 2008 12:41 pm
Subject: Re: [LF] Fwd: Draft for IPC-4101C
Sun Microsystems has found the STII formula to be overly simplistic,
with great potential for false confidence. In-depth qualification runs
for evaluating lead-free assembly board processing are still required.
The addition of new test methods such as fracture toughness may
potentially mitigate this requirement.?
?
Regards,?
Karl Sauter?
?
Stadem, Richard D. wrote, On 12/04/08 05:34:?
> I couldn't agree more. I don't understand why the STII formula
would?
> not be added with alacrity and dispatch.?
>?
> -----Original Message-----?
> From: Leadfree [mailto:Leg] On Behalf
Of Fox, Ian?
> Sent: Thursday, December 04, 2008 2:[log in to unmask] AM?
> To: [log in to unmask]
> Subject: Re: [LF] Fwd: Draft for IPC-4101C?
>?
> Werner, I like the STII concept and in my opinion not only should
it be?
> in 4101 it should also be included in the materials section of
2221.?
>?
> Regards?
> Ian Fox?
> Goodrich ECS?
>?
> -----Original Message-----?
> From: Leadfree [mailto:[log in to unmask]] On Behalf
Of Werner engelmaier?
> Sent: 03 December 2008 23:11?
> To: [log in to unmask]
> Subject: [LF] Fwd: Draft for IPC-4101C?
>?
>?
> Guys & Gals,?
> Doug Sober wrote:?
>?
> "I admit that we promised you consideration for the C Revision.?
We do?
> need some testimonials for people that feel that it has value.?
>?
>?
>?
>?
>?
> For sure your recipe makes sense and it does provide a guide to?
> lead-free assembly compatibility, however the materials picked by
this?
> method are normally the higher Tg, higher priced and more
specialized?
> FR-4.? >?
>?
>?
>?
>?
> Customers cannot always purchase?
> specification sheet 126 materials.?
>?
>?
>?
>?
>?
> But I would be willing to listen to the?
> testimonials. ?It is not going to happen for this revision
however.?
>?
>?
>?
>?
>?
> Doug"?
>?
> Keep those 'testimonials' coming. I guess we do technology by
democratic?
> principles.?
>?
> Of course, you do not need /126 for most applications. My take on
the 12?
> keyworded:?
> "Lead-free-FR-4" slash-sheet material groups in the C-rev is as
follows:?
>?
>?
> For Rev. C (Final Draft) /126, /129, /130 and /131 are fully
compatible?
> with?
> /126 and /130 being the best choices because of their lower
CTE(z), and?
> /99, /124, /125 and /128 limited; the others [/101, /121, /122,
/127]?
> keyworded:?
> "Lead-free-FR-4' may be problematic with LF-soldering
temperatures. >?
>?
> Just for reference, for Rev. B, /126 and /129 are fully
compatible, /99?
> and?
> /124 to a more limited extent. >?
> You should have an easily-applied tool to pre-select materials
likely?
> meeting your needs.?
>?
>?
> >?
> Regards,?
>?
> Werner Engelmaier?
>?
> Engelmaier Associates, L.C.?
>?
> Electronic Packaging, Interconnection and Reliability Consulting?
>?
> 7 Jasmine Run?
>?
> Ormond Beach, FL 32174 USA?
>?
> Phone: 386-437-8747, Cell: 386-316-5904?
>?
> E-mail: [log in to unmask],
Website: www.engelmaier.com?
>?
>?
> >?
> -----Original Message-----?
> From: Sober, Doug <[log in to unmask]>?
> To: [log in to unmask];
[log in to unmask]
> Cc: [log in to unmask];
tony senese <[log in to unmask]>?
> Sent: Wed, 3 Dec 2008 4:14 pm?
> Subject: RE: Draft for IPC-4101C?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
> Werner,?
>?
>?
>?
> ??
>?
>?
>?
> I admit that we promised you consideration for the C Revision.? We
do?
> need some testimonials for people that feel that it has value.?
>?
>?
>?
> ??
>?
>?
>?
> For sure your recipe makes sense and it does provide a guide to?
> lead-free assembly compatibility, however the materials picked by
this?
> method are normally the higher Tg, higher priced and more
specialized?
> FR-4.? >?
>?
>?
> ??
>?
>?
>?
> Customers cannot always purchase?
> specification sheet 126 materials.?
>?
>?
>?
> ??
>?
>?
>?
> But I would be willing to listen to the?
> testimonials. ?It is not going to happen for this revision
however.?
>?
>?
>?
> ??
>?
>?
>?
> Doug?
>?
>?
>?
> ??
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
> From:?
> [log in to unmask]
[mailto:[log in to unmask]]
>?
> Sent: Monday, December 01, 2008?
> 5:32 PM?
>?
> To: [log in to unmask]
>?
> Cc: Sober, Doug; [log in to unmask];?
> [log in to unmask]
>?
> Subject: Re: Draft for IPC-4101C?
>?
>?
>?
>?
>?
>?
> ??
>?
>?
>?
> Hi Tom,?
>?
> I am rather disappointed to find that the STII-concept has not
been?
> included in this draft. I was promised that the concept would get?
> serious consideration and be included in the C-revision 'if?
> appropriate'.?
>?
> Over 2 years have passed since I withdrew my NEGATIVE on the
B-revision,?
> and from what I can tell from the meeting minutes absolutely
nothing has?
> been done by the committee in this regard.?
>?
> The STII-concept has found favorable interest by users both in the
USA?
> and Europe, with some interest expressed in Asia as well. Its?
> effectiveness is clearly evident, it does not take anything away
from?
> any of the materials, it makes selection for suitability much
easier,?
> and it combines the impact of the major parameters affecting PCB?
> survival/reliability.?
>?
> So, clearly, the STII-concept is appropriate.?
>?
> As this draft stands, it will receive a NEGATIVE from me.?
>?
>?
>?
> Regards,?
>?
> Werner Engelmaier?
>?
> Engelmaier Associates, L.C.?
>?
> Electronic Packaging, Interconnection and Reliability Consulting?
>?
> 7 Jasmine Run?
>?
> Ormond Beach, FL 32174 USA?
>?
> Phone: 386-437-8747, Cell: 386-316-5904?
>?
> E-mail: [log in to unmask],
Website: www.engelmaier.com?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>?
>
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> ?
-- ? Karl Sauter?
? Principal Engineer, PCB Technology?
? Sun Microsystems, Inc.?
? 4120 Network Circle (Bldg. 12)?
? Santa Clara, CA 95054?
? Phone: (408) 276-3207?
?
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Karl Sauter
Principal Engineer, PCB Technology
Sun Microsystems, Inc.
4120 Network Circle (Bldg. 12)
Santa Clara, CA 95054
Phone: (408) 276-3207
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