Werner,
Actually, I am the Chair of IPC-4101, so don't blame Doug Sober.
In principle, I agree with what you say, but you are not the only one with an opinion and wanting to present data. I have at this time 7 requests to look at data to support a change to a present Test Method; to change minimum values; or to propose a new Test Method to determine the acceptability of a material to an existing slash sheet or use in a Lead-Free environment. This is on top of many requests to list the numbers in a different qualitative or quantitative method. There are a few slash sheets that have the minimum mandatory requirements defined that would facilitate their use as a true high-rel Lead-Free candidate, but there is a lot of work to do to gain consensus.
The best material in the world does not a process make and IMHO no dicy-cured FR-4 need apply for high-rel, high layer count, Class 3/3A Aerospace, Lead-Free compliant product. We need people to work together to help IPC-4101 be the best it can be at the present time. This work then has to be carried over to IPC-600, IPC-6011, IPC-6012 and IPC-2221. I have just finished the re-write of 6011 and 6012. We are working on the others in special groups. When this is done it has to be correlated with the requirements in IPC J-STD-001 and IPC-A-610.
Even having done all that, it is still imperative that the Designer and Engineer work together to establish Design Guidelines that will optimize the material and process choices covered in the aforementioned documents.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Monday, May 22, 2006 12:28 PM
To: [log in to unmask]
Subject: Re: [TN] Rohs Weeeeeee board material
Hi Valerie,
Valerie: Interestingly, IPC 4101 does not require any Tg testing. For Tg it
states
that those are "optional tests as agreed upon between user and supplier",
and they reference both TMA and DSC as "the tests" for Tg.
EW: That is one of the reasons that I have voted 'Negative' on the 4101 B
revision. The prime reason is the wide ranges of properties allowed on
each slash sheet. The problem is, that too many vendors in the committee
have too mch vested interest. We need to think more in terms oof 'Win-Win'
scenarios.
Valerie: At this point in time what little respect I had for the slash
sheets is totally gone. As far as I am concerned they are useful only in
the most general sense to differentiate one "family" of materials from
another; ie: polyimide vs epoxy or fiberglass reinforced vs aramid fibers,
and all the other permutations. Which means effectively that the only
portion of the slash sheet that has any value is the "description fields"
above the solid lines. Ok, maybe I exaggerate a little.. and I did go on
for a bit on this topic. If anyone thinks that specifying a slash sheet
means that they have "quality" material or "suitable" material, they are
mistaken. All they have done is describe the generic resin and
reinforcement; after that, it means almost nothing with regard to
performance and use.
EW: That is exactly my point. If the two of us can see that, where is
everybody else? The committee voted "NOT ACCEPTED" on all of my suggested changes and
want me to withdraw my "NEGATIVES."
Everybody, let Doug Sober <[log in to unmask]>, committee chair for 4101,
know, if you agree--lets swamp him [actually, he is a nice guy].
Werner
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