TECHNET Archives

May 2006

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Werner Engelmaier <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Mon, 22 May 2006 13:34:02 EDT
Content-Type:
text/plain
Parts/Attachments:
text/plain (61 lines)
Hi Valerie,
You are giving me a rather lengthy response—so I will go point by point.
1)
> The Isola site is also used to track order and ship status, invoicing, and
> dock to stock in addition to technical details; so it would be entirely
> appropriate that they do not just approve all comers but first understand
> who is requesting access to what - so they are asking for 24 hours to
> review the registration 
> A: If it works like that, it would be acceptable, BUT 5 days after asking for 
registration, i still have not heard from them. And why restrict access to 
technical data.

2)
> When I only see DSC, I subtract 10 degrees and call that value the
> equivalent to the Tg by TMA - and move on. 
> A: I do the same.

3)
> Since the IPC has test methods for all three tests, they are all valid. 
> A:   I think the IPC is doing a lot for the industry, BUT I would not go as 
far as you and say "Since the IPC has test methods for all three tests, they 
are all valid."

4)
> 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.
> A:   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. 

5)
> x,y-TE is below Tg, so it is low. Almost all FR4s with woven glass are
> somewhere between 10 and 14; and that number would also change in practice
> when one moves from a raw laminate core to a cured multilayer board. 
> A:   Well, those numbers do not make sense--where do 10 to 14 come from. I 
have never seen values this low-they typically are 16+/-2 ppm/C. When I had one 
of these materials measured, the values turned out to be CTE(x,<Tg)=21.4 and 
CTE(y,<Tg)=16.0. Can you imagine the incorrect Design for Reliability for the 
SMT solder joints based on CTE's of 11 and 13?

6)
> In general I would say that USA laminators didn't pick up on the
> enormity of the research and development that it would take for RoHS
> capable materials; ie: able to withstand lead-free process temperatures.
> A:   AMEN, to that. I am already seeing the consequences.


Werner

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2