Jack
Rather than specifying a material type, many specify the material properties
such as the ones in your original email. In that way, you do not put your
fabricator in box that might later impact your cost.
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: "Jack Olson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, November 02, 2007 11:06 AM
Subject: Re: [TN] Bare-Board Materials for Lead-Free Soldering
> OK, I didn't get much response to my "informal poll"
> (thanks Dewey and Werner!),
> so I'll ask one more specific question before I start getting grouchy
> (grin)
>
> If you attend Lead Free Reliability presentations by people like
> Werner Englemaier or Gary Ferrari (highly respected in our industry)
> they recommend a material like IPC-4101/126 or /129
>
> If you go to websites like Merix (also highly respected)
> http://www.merix.com/RoHS+_+Lead+Free.aspx?id=4
> they recommend something different
>
> (so don't say, "ask your fabricator")
>
> Does anyone have knowledge that would help clarify the discrepancy?
> Is the /126 /129 just SUPER reliable over /99 and /124?
> (ok, that was more than one question)
> we are auomotive, but I know I am going to be asked to justify
> the added expense sooner or later...
> maybe I'm just looking for a group hug.
> sheep mentality.
> baaa....
>
> and no, I'm not a materials expert, but I MUST call out SOMETHING.
> and SOON!
> (I'm trying to wade through the materials info in the new Printed
> Circuits Handbook, but its still confusing.
> But hey, maybe I WILL be a materials expert by next week, huh?)
>
> onward thru the fog,
> Jbro
>
>
> On 10/29/07, Whittaker, Dewey (EHCOE) <[log in to unmask]>
> wrote:
> >
> > Yes and a few additional requirements.
> > Yes and /129 also.
> > It depends (cha-ching).
> > Yes.
> > Yes.
> > 1.5 mil avg. with 1.2 mil minimum.
> >
> > Dewey
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> > Sent: Monday, October 29, 2007 10:28 AM
> > To: [log in to unmask]
> > Subject: [TN] Bare-Board Materials for Lead-Free Soldering
> >
> > I'm hoping to get an informal poll of fabricators and people who specify
> > bare board materials.
> >
> > There's been a lot of literature and presentations lately that
> > recommend numbers for better material performance under the higher
> > soldering
> > temperatures.
> >
> > IPC-4101/126
> > Tg=170 or higher
> > Td=340 or higher
> > maximum expansion 3%
> > etc.
> >
> > I'm not questioning the wisdom of the numbers, I'd just like to know
> > whether
> > everyone (who is doing lead free soldering) is really USING these
> > numbers?
> > Or this material? Is there no wiggle room anymore? (EVERY example I see
> > now,
> > lists /126 material)
> >
> > I've also been advised to use a thicker minimum hole wall thickness than
> > before. Is that common now? >1mil?
> >
> > thanks,
> > Jack
> >
> >
>
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