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May 2010

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Subject:
From:
Werner Engelmaier <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Werner Engelmaier <[log in to unmask]>
Date:
Fri, 21 May 2010 01:35:40 -0400
Content-Type:
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 Hi Jack,
One important parameter you did not asked for is the thermal expansion.

 S1000-2 is a Shengyi product with a TE of 2.6% [very good] and an STII=230.
IT-180 is from ITEQ with a TE=3.0% and a STII=220.
The slash sheet designation only sets the material category these materials fall into, and some minimum properties, which both exceed.
But to choose depends on your PCB design and your product application.
Werner


 

 

-----Original Message-----
From: Jack Olson <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, May 20, 2010 9:02 pm
Subject: Re: [TN] My first RoHS circuit board!


Thanks for the advice (everyone!)

Here's an update if anyone is interested:

I sent a sample fab dwg to our primary supplier (in China) with notes
that incorporated several of your recommendations (the main one being
material /126 170Tg 330Td 30minT288) to see if it would cause them any
problems before I send them the real order. They looked at it and said "No
Problem. Our default material meets those requirements"

So I told them that since I'm trying to learn about his I would like to know
what kind of material it was, and could they send me a data sheet.

Well, they sent a data sheet for something called S1000-2 which it says
right on the data sheet is /99, but the parameters are 175Tg 335Td 10minT288
So I wrote back and asked if they had another material that is more robust,
and they sent me data for a material called IT-180 which it says is /24
Tg180 Td350 >60minT288(?)

I really don't think they are trying to be deceptive, but that they honestly
think the only thing that matters is the Tg and Td numbers. And those
numbers look pretty good!

So now I'm wondering how hard I should push to get them to literally buy
/126, and if by forcing them to use a material they aren't familiar with, if
there will be other problems related to drilling, or desmear or plating or
routing or whatever could be different from the /99 they are used to. Is
there a "learning curve" with these materials?
Jack

.
On Tue, May 18, 2010 at 4:41 PM, Whittaker, Dewey (EHCOE) <
[log in to unmask]> wrote:

> Jack,
> Just designing for RoHS compliance does not dictate the use of non-dicey
> cured material. If you are designing a fully compliant, complex,
> Lead-free design that will be exposed to a minimum of two lead-free
> reflow profiles and one wave solder operation and expect it to work for
> twenty plus years, then no dicey-cured FR4 shall apply. IPC-4101/126 and
> /129 are phenolic cured materials which have demonstrated a robustness
> that is up to the challenge.
> Dewey
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Tuesday, May 18, 2010 2:29 PM
> To: [log in to unmask]
> Subject: [TN] My first RoHS circuit board!
>
> Well, we avoided it as long as we could, but now I have to design for
> RoHS
> compliance.
>
> I'm basically following Werner's recommendations (which don't conflict
> with
> anyone else's as far as I know), but I'm confused about one aspect of
> material:
> Several sources have stated that its better to use "NON-DICEY" material,
> but
> none of the IPC-4101 slash sheets mention dicy or non-dicy (or
> dicyandiamide).
> If we are trying /126 material, do we still have to specify non-dicy?
>
> thanks,
> Jack
>
>
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