3/4/98
embedding some ceramic powder particles in resin prior to ion beam thinning
(since they are far too large to be electron transparent without thinning).
I was thinking that embedding in a conductive resin may be a good idea.
Some have suggested mixing carbon (carbon black I assume) with the resin.
I have heard in the past about use of a silver loaded resin. Is this
readily available? Is it horribly expensive? Does anyone know of a vendor
who sells this in the UK?
Also, some epoxy resins have been optimised for materials work so that they
can be cured to a high hardness value. How do silver or carbon loaded
epoxies compare with this?
Thanks for any help you can give.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Ian MacLaren, Tel: (44) (0) 121 414 3447
IRC in Materials for FAX: (44) (0) 121 414 3441
High Performance Applications, email: I.MacLaren@bham.ac.uk
The University of Birmingham, http://web.bham.ac.uk/I.MacLaren/
Birmingham B15 2TT,
England.
in the US. All I have seen, however, has rather large Ag flakes...
Along this thread... I am still waiting for the chemists to
develop a thermoplastic version of intrinsically conductive
plastic. Intrinsically conductive polymer is around, but all I
have seen is milled thermoset - May as well use carbon or metal
powders....
Woody White
McDermott Technology, Inc
for surface SEM observation
for example. But don't forget, they are composite materials, i.e.
non-conductive resin loaded with enough
conducting material (Cu, Ag whatever) to make them MACROSCOPICALLY conductive.
In microscopy application, their composite structure quickly appears and limit
their usage. For example,
their are useless to look at edges of conductive material because the
non-conductive resin portion
in-between the conductive particles will charge up exactly as pure polymer and
blur out the picture.
For your ion-milling application I suspect the same holds true but I haven't
try myself. So just be aware of this
problem if doesn't work.
BTW they are available from any electron microscopy accessories vendor.
Jean-Marc Boichat email: jean-marc.boechat@chma.mhs.ciba.com
EM LABS FO 5.1 phone:+4126 435 6979 fax: +4126 435 6907
Ciba research Center
P.O. Box 64
CH- 1723 Marly 1 When things go wrong, don't go with them!
Switzerland
electrically conductive. It is rated at 50 ohm/cm, but I measure about
10k ohms/cm.
Metal particles cast and polished in this material show no charging when
imaged at fast or slow rates in BSE or SE mode in my SEMQ. Nice to see
the original colors of a material through the light optics. X-ray count
rates seem OK.
It may be suitable for high vacuum since it contains no solvents. I
can't melt a hole in the stuff with a 100 nA focused beam.
Adhesion is excellent. In fact, it sticks to silastic mold perimeters.
Mixing is a little fussy. 3 parts to 100. A perfect mix might get the
50 ohm/cm value. Shelf life is supposed to be less than a year and it's
expensive.
The grain size of the carbon filler is relatively coarse. Colloidal
graphite might be better.
This posting is definitely to help you people and not Master Bond, a
company I did not find especially cooperative toward experimenters.
Master Bond is located in Hackensack, NJ. Phone 201 343 8983.
Bart Cannon
Cannon Microprobe
Seattle
likely to achieve the aim, which was the elimination of charging in the SEM
of DIFFICULT non-conductors embedded in resins.
Consider that most elemental standards for EDS are mounted in resin blocks.
Furthermore, in WDS especially much higher specimen currents are used than
in normal SEM. Those standards have a 20nm, heavy carbon coating, but this
is not as conductive as is the Au coating employed in SEM. Normally in
analysis BS detection is used but charging in secondary mode is uncommon. If
the argument was right that resin embedded non-conductors charge because of
the resin, EDS and WDS would have a few additional problems. WHY THEN SHOULD
CONDUCTING RESINS SOLVE CHARGING PROBLEMS IN SEM?
The difference is the type of embedded material. All standard materials used
must permit a fine polish and cannot be porous or highly fractured. Such
materials will have a continues conducting layer accross the surface and not
charge.
The original correspondent has charging problems because of the highly
porous nature of his specimens. Better (angled) coatings and optimising the
instrument's parameters to minimize charging will hopefully solve his
problem.
Jim Darley
ProSciTech Microscopy PLUS
PO Box 111, Thuringowa QLD 4817 Australia
Phone +61 7 4774 0370 Fax: +61 7 4789 2313
Great microscopy catalogue, 500 Links, MSDS, User Notes
**************************** www.proscitech.com.au *
The last time this thread was on the List, I asked for a supplier of the
German-made Technovit 5000, which is a copper-filled, cold-curing resin I
have used in the past. The Canadian supplier was no longer carrying it.
Energy Beam Sciences (www.ebsciences.com/) replied that they could get it on
5 to 7 weeks delivery. It is about $200US for 500 ml. liquid and 1000 g.
copper powder, but this lasts a long time. The quality is O.K., with some
resin areas that charge, but it is essential for looking at edges of
material you don't want to carbon coat or heat up. Most metallurgical
companies carry a conductive hot-press material.
Regards,
Mary
Mary Mager
Electron Microscopist
Metals and Materials Engineering
University of British Columbia
6350 Stores Road
Vancouver, B.C. V6T 1Z4
CANADA
tel: 604-822-5648
fax: 604-822-3619
e-mail: mager@interchange.ubc.ca
Yet another question from the unpredictable world of multi-user facilities.
One of our users embeds samples in epoxy and polishes them to eliminate
topographical variables. He requires both imaging and EDS, which precludes
metal coating for conductivity.
He was wondering about the availability of epoxies containing conductive
components, which might allow us to use high-vacuum SEM with secondary
electron imaging. Does such a thing exist? Has anyone ever used a
standard epoxy and added their own conductive "secret recipes" before
polymerizing?
I'm aware that carbon coating is an option, as well as painting conductive
stripes of colloidal carbon or silver to the edge of the embedded materials
and down to the aluminum stub. The idea of a conductive epoxy is
intriguing, though, for the time and mess-saving possibilities.
As usual, thanks in advance for the always helpful replies I get to these
queries.
Randy Tindall
Electron Microscope Laboratory
Box 3EML
New Mexico State University
Las Cruces, NM 88003
rtindell@NMSU.Edu
including at least four that are electrically conductive; all contain
silver. I have not used any of them myself. BTW, their EPO-TEK 353ND is
the same as Gatan's G-1, which I do use.
Call them at 800 227 2201 for a catalog.
Michael K. Cinibulk
UES, Inc.
Air Force Research Laboratory
Materials and Manufacturing Directorate
Wright-Patterson AFB, OH 45433-7817
937 255 9339 phone
937 656 4296 fax
cinibumk@ml.wpafb.af.mil
was a hot-preesed, thermosetting material from Beuhler or Leco. However,
there was still a substantial fraction of the surface that was
nonconductive. I don't recall if we could count on it providing a conducting
path to ground. I think we C-coated most of our samples anyway.
At that time I was looking at S in coal and had little trouble from the C
coating.
Warren E. Straszheim
23 Town Engineering
Iowa State University
Ames IA, 50011
Phone: 515-294-8187 FAX: 515-294-8216
E-Mail: wesaia@iastate.edu (or: wes@ameslab.gov)
http://www.marl.iastate.edu/marl/ (re: SEM)
http://www.public.iastate.edu/~iprt_info/cfce/ (re: coal)
CT) used to sell a product called "E-Solder No. 3022," which is a
conductive epoxy containing silver. It was intended as a substitute for
solder in electronics repair when soldering isn't possible. I haven't
used it for SEM. Hope this is helpful.
Scott Schwinge
University of Washington
Friday Harbor Labs
360-378-2165
schwinge@fhl.washington.edu
169-10005) with carbon particles.
Allied High Tech (800) 950-9347 or (310) 635-2466
or
Electron Microscopy Sciences has a Conductive Cold Mount (# 50452-01) with
copper particles.
EMS (800) 523-5874 or (215) 646-1566
Hermann Reese
IACSA Mexico-City
iacsa_df@CompuServe.COM
Well, this is maybe not exactly an unswer which one may excpect,
but it may give an idea how to deal with the problem.
We are using old electric discharge machine and it requires from
time to time the samples to be glued. So to make, the glue or
epoxy conaductive some carbone powder is add.
Regards
Witold Zielinski
Warsaw University of Technology
Narbutta 85, O2-524 Warszawa
Poland
WIZIEL@inmat.pw.edu.pl
I have used the conductive cold-curing resin: "Technovit 5000" for several
years, but the last time I tried, my usual suppliers no longer carried it.
Electron Beam Sciences Inc. informed me that they have it available, when I
asked on the listserver. Several other suppliers of mounting media have
hot-press, conductive mounting media (Leco, etc.). For my usual
metallurgical mounts, I mount in normal epoxy, poloish, then paint all of
the top epoxy surface with carbon paint, overlapping the metal slightly.
Then run a stripe down the side to the stub to connect. I use the carbon
evaporative coating if I want to look at the very edge of the sample or if
the sample is not conductive, and only use the conductive resin if the
sample cannot be coated and the edge is important.
Mary Mager
Electron Microscopist
Metals and Materials Engineering
University of British Columbia
6350 Stores Road
Vancouver, B.C. V6T 1Z4
CANADA
tel: 604-822-5648
fax: 604-822-3619
e-mail: mager@interchg.ubc.ca
Electron Microscopist
Metals and Materials Engineering
University of British Columbia
6350 Stores Road
Vancouver, B.C. V6T 1Z4
CANADA
tel: 604-822-5648
fax: 604-822-3619
e-mail: mager@interchg.ubc.ca
Many thanks for the helpful replies after my recent inquiry about
conductive epoxies for SEM specimen embedding. I am passing on the replies
for other listmembers who may have an interest in this.
>From Mark Darus:
> I use "PolyFast" available from Struers. The description on
>the container states; Phenolic hot mounting resin with carbon filler
>for edge retention and examination in SEM.
> A code on the container is: FAPSA
> 40100036
> 6062-5754
> Look in a Struers catalog for more information, or call them for one
>at 1-888-Struers.
>
>From Matthew Libera:
>I had a similar problem when I was a grad student. I used conductive
>epoxies from a company called Epotek in Billerica, Massachusetts. I
>never had great success getting the conductive epoxy to cure properly,
>however. Perhaps you will have more success.
>
>
>
>From Phil Oshel:
>Various companies make silver-impregnated epoxy for making conductive
>joins--such as gluing a new target onto an (old) Hummer sputter-coater
>electrode. Don't know if this would work directly for embedding, but it
>suggests that you could buy silver painting for mounting specimens that's
>dissolved in acetone (EMS sells this, I think, others likely do also), and
>use it in the embedding resin.
>From Winton Cornell:
>what about simply mixing graphite into the epoxy as it's prepared?
>
>
>From Brian Demczyk:
>Yes, there most certainly are conductive epoxies (containing, for example,
>silver). Check any of the EM supply houses. You might also want to check
out a company called EPON-Tek, or something
>of the like.
>
>
>From John Hunt:
>
> Sure. Buehler and probably Struers, LECO etc. make conductive
>material for mounts. The copper ones were removed from the market
>some years ago but Al filled and Carbon filled ones are still
>available, I believe. The powder is used in a hot hydraulic ram type
>mold. The specimen is placed with the side of interest face down. The
>mounts are usually inch or inch and a quarter diameter. The sample
>is then ready for polishing. Coating is not necessary unless the
>sampled is non-conductive in which case one might as well use epoxy.
>
>From Eunsung Park:
>I usually use a Ag-dispersed epoxy (from SPI) to embed small specimens
>for both SEM and TEM work. Howver, it doesn't eliminate the necessity of
>conductive coating since the epoxy contains non-conducting polymers. Another
>problem is that the eopxy is not cheap (I fon't have the price list in
handy).
>It is surely worth to try, though. Good luck.
>
>From Warren Straszheim:
>We used to use some copper-filled diallyl pthallate (sp?) to embed coal. It
>was a hot-preesed, thermosetting material from Beuhler or Leco. However,
>there was still a substantial fraction of the surface that was
>nonconductive. I don't recall if we could count on it providing a conducting
>path to ground. I think we C-coated most of our samples anyway.
>
>At that time I was looking at S in coal and had little trouble from the C
>coating.
>
>
>From Michael Cinibulk:
>
>Epoxy Technology, Inc. manufactures a complete spectrum of epoxies
>including at least four that are electrically conductive; all contain
>silver. I have not used any of them myself. BTW, their EPO-TEK 353ND is
>the same as Gatan's G-1, which I do use.
>
>Call them at 800 227 2201 for a catalog.
>
>
>From Scott Schwinge:
>Acme Conductive Adhesives (Division of Allied Products Corp. / New Haven,
>CT) used to sell a product called "E-Solder No. 3022," which is a
>conductive epoxy containing silver. It was intended as a substitute for
>solder in electronics repair when soldering isn't possible. I haven't
>used it for SEM. Hope this is helpful.
>
>From Hermann Reese:
>Allied High Tech Products has a Conductive Mounting Powder (order #
>169-10005) with carbon particles.
>Allied High Tech (800) 950-9347 or (310) 635-2466
>
>or
>
>Electron Microscopy Sciences has a Conductive Cold Mount (# 50452-01) with
>copper particles.
>EMS (800) 523-5874 or (215) 646-1566
>
>
>"I have no commercial or financial interest in the companies stated above,
>except within Mexico."
>
>
>From Witold Zielinski:
>Well, this is maybe not exactly an unswer which one may excpect,
>but it may give an idea how to deal with the problem.
>We are using old electric discharge machine and it requires from
>time to time the samples to be glued. So to make, the glue or
>epoxy conaductive some carbone powder is add.
>
>
This is what I have received to date. Thanks to all and my apologies if I
missed anybody.
Randy Tindall
Electron Microscope Laboratory
Box 3EML
New Mexico State University
Las Cruces, NM 88003