Thanks a lot, Joyce,
I have the article co-writer on-line now, and he promised to give a hand. Let's see what comes out.
cu
Ingemar
Inge,
the recent issue of CPMT has following paper:
Effect of Ag Particle Size on Electrical Conductivity of Isotropically
Conductive Adhesives
L. Ye, Z. Lai, J. Liu, and A. Thölen
[p. 299]
http://www.cpmt.org/past_trans/epm_toc_9910.html
you may be able to find the paper you wanted in the reference...Good luck.
jk
At 02:34 PM 2/14/00 -0800, you wrote:
>Ingemar
>
>Good to hear you're out there. Unfortunately, I don't have any such paper.
>
>The issue you bring up is basic metal-Si (Schottky barrier diode)
>semiconductor physics...not a focus to most of those in the PWB world. You
>can read about this in almost any solid-state physics book. Typical voltages
>to overcome the barrier can be as high as 0.5-1.0V, although it depends on
>the doping level and other related stuff. Silver epoxy can be a bit more
>complicated because it forms a very thin sulfuric (I think, if not it's
>oxide) coating (from reacting to air and the epoxy resin) that acts like an
>insulator that get's broken down easily, but can affect the Schottky
>interfacial properties. Under these situations, you have various values of
>Schottky barriers (think of it as a distribution of resistor values with a
>critical turn-on voltage). Because the metal-Si interface is dictated by
>charge carrier density and that this density is exponential with both
>temperature and doping, it gets very squirrelly (for you non-english
>speaking folks..."weird").
>
>There is also the situation where the Si is doped such that you form Ohmic
>contacts (your standard contact resistance), which also has some variation
>in values, but not as severe in affecting electronic current because the
>charge density does not vary significantly.
>
>In short, if you are looking into this, avoid non-wire bonded or metal
>bumped Si devices. Look into IEEE journals in the mid-80's or look at
>recent work in anisotropic conductive adhesives in flat panel displays
>papers of the 90's. Call Hitachi Chemical (they are the big supplier) or 3M
>(they have products out there and probably a lot of publications/patents)
>for information on the adhesive electrical properties. Lastly, when I think
>of RF, I track down contacts at Teradyne (think military).
>
>Good luck
>
>Carey
>
>-----Original Message-----
>From: Ingemar Hernefjord (EMW) <[log in to unmask]>
>To: [log in to unmask] <[log in to unmask]>
>Date: Monday, February 14, 2000 2:19 AM
>Subject: [TN] GHz and filled adhesives
>
>
>>Gidd Moerning all,
>>I have something that may be too far from PWB, but I dare try: who knows
>about noise in metal filled adhesive joints? Many years back people found
>that the conducting mechanism in thin silver epoxy joints reminds of that in
>semiconductors, i.e. you have something like a diode, but very small
>forward current drops and hardly measureable reverse blocking, anyway, it
>may cause noise. Unfortunately, I have lost the article and the guy who made
>research in this issue (possibly IBM, Raytheon, HP... was american I'm
>sure). Anyone out there with experience from this field and RF-noise?
>>txs in advance
>>Ingemar Hernefjord
>>Ericsson Microwave Systems
>>
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