Substates typically have anisotropic CTEs in X/Y and Z because of the effect of the glass reinforcement limiting expansion in the X/Y direction. CB-100 is a silver filled epoxy. Unless there is something about the size and shape of the filler and application method that would provide an orientation to the filler (I'm unaware of any of this being done with this material), CB-100 should have isotropic CTE values.
Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263
----------
From: Yuan Li[SMTP:[log in to unmask]]
Reply To: TechNet E-Mail Forum.;Yuan Li
Sent: Tuesday, March 25, 2003 10:02 AM
To: [log in to unmask]
Subject: Re: [TN] FW: [TN] TCE above Tg for Dupont CB100 silver resin
Is it the CTE on Z-direction?
The CTEs on X- and Y- directions above Tg are lower for BT substrates.
-----Original Message-----
From: peter blokhuis [mailto:[log in to unmask]]
Sent: Tuesday, March 25, 2003 6:07 AM
To: [log in to unmask]
Subject: Re: [TN] FW: [TN] TCE above Tg for Dupont CB100 silver resin
Methode Electronics http://www.methode.com/mdc/via.pdf
has a similar material (their 1210) with a Tg of
190ppm/C above their Tg of 120C. Perhaps this will be
close enough for your needs.
Peter Blokhuis
--- joyce <[log in to unmask]> wrote:
> if it is standard epoxy filled with silver, my guess
> is 3x TCE above Tg.
> With absent of data and not going to do any test
> (which I think you
> really should do the test... rather than question it
> endlessly, why not
> just pay few $ run a TMA?), I would design per 3x
> TCE above Tg, provide
> you cure it properly. On the other hand, why Dupont
> not provide above
> Tg data? very strange...
>
> my 2 cents.
>
> jk
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of
> Mcmaster, Michael
> Sent: Monday, March 24, 2003 5:41 PM
> To: [log in to unmask]
> Subject: Re: [TN] FW: [TN] TCE above Tg for Dupont
> CB100 silver resin
>
>
>
> I'm going to have to disagree with Guy on this.
> There's nothing that
> says CTE above Tg has to be non-linear. Nor is
> there anything that says
> it has to be linear, especially when working with
> systems like today's
> high performance epoxy systems.
>
> There are multiple ways to define, measure, and
> determine Tg, but it is
> generally regarded as the temperature below which
> free rotations cease
> because of intramolecular energy barriers. In other
> words, the material
> acts as a glass.
>
> Above Tg the polymer achieves what is known as
> segmental mobility. The
> reason for this is that as you heat the material up
> it expands (the
> CTE). This expansion results in an increase in free
> volume. Below, Tg,
> the free volume is too small to allow segmental
> mobility, whereas above
> Tg, the free volume is large enough.
>
> The Tg the shows up as a discontinuity in the
> specific volume vs
> temperature curve. For amorphous polymers,
> especially something like a
> cross-linked epoxy, the transition is not clean.
> Difference in cross
> link density, segment length, initial free volume
> and other factors mean
> that different sections of the material achieve the
> necessary free
> volume for segmental mobility at different
> temperatures. As a result,
> the glass transition is usually not abrupt (like
> say, the melting of
> water, another transition). So while the Tg is
> reported as a single
> temperature, that's rarely true. The temperature is
> usually arrived at
> by extrapolating the specific volume vs temperature
> curves above and
> below Tg. The reported Tg is the intersection of
> the two lines, even
> though the transition itself started below and
> continued above this
> temperature.
>
> For CTE above Tg to be restricted to "non-linear" or
> "linear" is
> unfounded. I've seen plenty of TMA scans that
> exhibit linear behavior
> for at least some section above the Tg. I've also
> seen materials that
> exhibit very non-linear behavior. Much of this has
> to do with the
> highly variable structures and compositions of
> polymeric materials. You
> have materials that are difunctional,
> tetrafunctional, mulitifunctional
> and then the co-polymer blends that tend to exhibit
> multiple transitions
> to the point where you can't find two lines from a
> TMA scan to
> extrapolate to an intersection. In some cases, it's
> nearly impossible
> to get a good Tg determination from TMA alone and
> alternative methods
> such as DSC and DMA must be used. But these look at
> properties other
> than volume to determine the transition and don't
> necessarily give the
> same result.
>
> And I'm guessing that you don't really care whether
> it's truly linear or
> not as along as it's a reasonable approximation of
> the CTE in the
> temperature range of interest. In all likelihood
> you want to know how
> the material is going to perform during reflow
> soldering (from below to
> above Tg). And maybe the properties during the
> operational life (likely
> below Tg). So you need to know the Tg, preferably
> measured with TMA
> since that is how CTE is measured also. You need to
> know the
> temperature range for the CTE measurements. You at
> least want the value
> above and below Tg. Reporting and using a CTE value
> that is the
> combination of the values above and below Tg is not
> of any practical
> value. The material exhibits this particular
> behavior only at one very
> specific temperature during the transition phase.
> It's akin to a
> stopped watch being right twice per day.
>
> Like you, I've had no luck determining the CTE of
> CB-100 above Tg.
>
> Mike McMaster
> RF Product Engineer
> Merix Corporation
> 503-992-4263
>
>
>
> ----------
> From: Arbour,
> Michel[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;Arbour, Michel
> Sent: Monday, March 24, 2003 6:10 AM
> To: [log in to unmask]
> Subject: [TN] FW: [TN] TCE above Tg for
> Dupont CB100 silver resin
>
>
> > OK,
> > So the values for ZTCE > Tg given in the material
> specs or various
> > articles
> > are linear approximation of the behaviour of ZTCE
> >Tg . Right ??
> >
> > And the Zaxis expansion% (50 to 288C) is the
> "real" value ?
> >
> > Ref. : circuitree magazine Feb. 2001: High
> reliability/Low CTE epoxy
> > technology,
> >
> >
> >
> > > -----Original Message-----
> > > From: Guy Ramsey [SMTP:[log in to unmask]]
> > > Sent: 21 mars, 2003 16:01
> > > To: 'TechNet E-Mail Forum.'; 'Arbour, Michel'
> > > Subject: RE: [TN] TCE above Tg for Dupont
> CB100 silver resin
> > >
> > > TCE above Tg is non-linear. What you're asking
> for is like asking
> for
> > > the distortion characteristics of a amp is after
> clipping.
> > >
> > > > -----Original Message-----
> > > > From: TechNet [mailto:[log in to unmask]] On
> Behalf Of Arbour, Michel
>
> > > > Sent: Friday, March 21, 2003 2:52 PM
> > > > To: [log in to unmask]
> > > > Subject: [TN] TCE above Tg for Dupont CB100
> silver resin
> > > >
> > > >
> > > > Hello Techies,
> > > > By any chance, would you know what is
> the TCE > Tg
> > > > for Dupont CB100 silver resin ??
> > > >
> > > > Can't get that info from DuPont's
> Micro-Circuit
> > > > Materials group in the U.S. . They have not
> measured that
> > > > characteristic they said...
> >
> >
> ---------------------------------------------------
>
=== message truncated ===
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