RE: Conductive Coatings/Conductive Plastic

[John Juhasz]

Thanks to all who responded to my message (below)regarding
conductive coatings/conductive plastics.
Everyone made some good points. 

GE Interlogix

John Juhasz
Fiber Options Div.
Bohemia, NY

-Original Message-
From: John Juhasz [mailto:jjuh...@fiberoptions.com]
Sent: Tuesday, March 19, 2002 8:42 AM
To: 'emc-p...@ieee.org'
Subject: Conductive Coatings/Conductive Plastic



Seeking comment  on Conductive Coatings vs. Conductive Plastic

Having dealt with metal (primarily steel) enclosures, my knowledge
of conductive coatings/conductive plastics is strictly based on
what I have been able to gleen from simple research and some conversation.

It is my understanding the conductive plastic (metal fibers mixed with
the plastic) is less effective at high frequencies ( >200MHz) than
plastic with a conductive coating  (i.e. electroless plating). 
Further, from a processing perspective (notwithstanding the shielding
effectiveness),
if good contact between mating pieces is required, conductive plastic
is not a top ranked choice - the amount of fiber that is
actually exposed to make contact is difficult to control and filing during
product assembly may be required to expose sufficient fiber.
And in both cases - SE and physical contact - the preparation (mixing) 
of the plastic/metal fiber needs to be tightly controlled (and is more
difficult to control), with potential for greater variances from to batch to
 batch than there is for plated plastic.

Comments please.


GE Interlogix

John A. Juhasz
Product Qualification &
Compliance Engr.

Fiber Options Div.
Bohemia, NY 11716






---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

Re: Conductive Coatings/Conductive Plastic

[Doug McKean]

Did some research into switching over from 
conductive coated plastics to conductive plastics.
The turn off was due to the metallic additions to 
the plastic with conductive plastics, the molds 
wore out faster than plastic molds. Tooling was 
expensive for the product in mind, so I have no 
idea if that's a factor with yours.  

- Doug McKean 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

RE: Conductive Coatings/Conductive Plastic

[Gary McInturff]

John, from my research on the topic long ago (we decided against it by 
the way) this is pretty much what I found. Another issue to be concerned with 
on the fibers is that generally they are part of the plastic enclosure itself, 
and as such they cause problems with the case tooling, Including wearing it out 
much faster. New tools aren't cheap. The electoless coatings etc, have a hidden 
cost in the EPA requirements for applying this stuff. You will be paying for 
that on each part as well. Make sure you know the true cost of the metallized 
part compared to the metal part- that will have a product volume component to 
it. The tool guys will have to watch radii and small parts to make certain they 
can be coating and that the material doesn't wick away from edges and corners.
This was a while ago - so maybe some of the problems have been solved.
Gary
-Original Message-
From: John Juhasz [mailto:jjuh...@fiberoptions.com]
Sent: Tuesday, March 19, 2002 5:42 AM
To: 'emc-p...@ieee.org'
Subject: Conductive Coatings/Conductive Plastic



Seeking comment  on Conductive Coatings vs. Conductive Plastic

Having dealt with metal (primarily steel) enclosures, my knowledge
of conductive coatings/conductive plastics is strictly based on
what I have been able to gleen from simple research and some conversation.

It is my understanding the conductive plastic (metal fibers mixed with
the plastic) is less effective at high frequencies ( >200MHz) than
plastic with a conductive coating  (i.e. electroless plating). 
Further, from a processing perspective (notwithstanding the shielding
effectiveness),
if good contact between mating pieces is required, conductive plastic
is not a top ranked choice - the amount of fiber that is
actually exposed to make contact is difficult to control and filing during
product assembly may be required to expose sufficient fiber.
And in both cases - SE and physical contact - the preparation (mixing) 
of the plastic/metal fiber needs to be tightly controlled (and is more
difficult to control), with potential for greater variances from to batch to
 batch than there is for plated plastic.

Comments please.


GE Interlogix

John A. Juhasz
Product Qualification &
Compliance Engr.

Fiber Options Div.
Bohemia, NY 11716






---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

RE: Conductive Coatings/Conductive Plastic

[Robert Wilson]

I've had a fair amount of experience with both conductive plastics, and
conductive coatings. Your comments are basically correct. 

A lot depends on what you are trying to achieve, both in terms of
attenuation at a particular frequency, and how much actual attenuation
you need. In one project I was involved with, we needed around 60dB of
attenuation at >400 MHz. Conductive plastics were mostly useless,
although the ones that were best (but still not good enough) were those
filled with long strand stainless steel. As you mention, one of the big
problems is making contact, since there tends to be a microscopic film
of insulating plastic formed over the surface of the molded object. In
this project, we achieved excellent results with selective electroless
copper plating (covered with a thin "flash" of nickel for corrosion
resistance). Similar excellent results were obtained using Spraylat's
non-corroding copper "paint". The results were almost identical to using
a die cast aluminum case at this frequency (the device was a 416 MHz, 5
Watt, hand held search and rescue satellite transmitter).

The usual nickel-bearing paints were useless at this high frequency, and
carbon-bearing paints were absolutely hopeless. The high resistivity of
both relegates them to low frequency, low attenuation requirements. 

Another reasonable choice is Zinc Arc Deposition. Even though zinc has
relatively poor conductivity, this process lays on so much of the stuff
(up to 0.1mm, or 0.004"), that the overall resistivity is relatively
good. Of course, the extra thickness can cause other problems in
assembly and so on.

As far as conductive plastics are concerned, we found that the best (but
still not great) results were obtained with high percentages of LONG
STRAND stainless fiber content. Toshiba's "EMI CLEAR" line of resins
also seemed somewhat promising. But one significant problem with these
and other "filled" conductive resins is that the surface finish is
lousy. In general, they require painting (with masking of the critical
areas) after moulding to be "presentable", and this costs almost as much
as simply spraying a decent conductive coating on ordinary plastic,
which would work better anyway!

Bob Wilson
TIR Systems Ltd.
Vancouver.

-Original Message-
From: John Juhasz [mailto:jjuh...@fiberoptions.com] 
Sent: March 19, 2002 5:42 AM
To: 'emc-p...@ieee.org'
Subject: Conductive Coatings/Conductive Plastic


Seeking comment  on Conductive Coatings vs. Conductive Plastic

Having dealt with metal (primarily steel) enclosures, my knowledge
of conductive coatings/conductive plastics is strictly based on
what I have been able to gleen from simple research and some
conversation.

It is my understanding the conductive plastic (metal fibers mixed with
the plastic) is less effective at high frequencies ( >200MHz) than
plastic with a conductive coating  (i.e. electroless plating). 
Further, from a processing perspective (notwithstanding the shielding
effectiveness),
if good contact between mating pieces is required, conductive plastic
is not a top ranked choice - the amount of fiber that is
actually exposed to make contact is difficult to control and filing
during
product assembly may be required to expose sufficient fiber.
And in both cases - SE and physical contact - the preparation (mixing) 
of the plastic/metal fiber needs to be tightly controlled (and is more
difficult to control), with potential for greater variances from to
batch to
 batch than there is for plated plastic.

Comments please.


GE Interlogix

John A. Juhasz
Product Qualification &
Compliance Engr.

Fiber Options Div.
Bohemia, NY 11716






---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://ieeepstc.mindcruiser.com/
Click on "browse" and then "emc-pstc mailing list"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Ron Pickard:  emc-p...@hypercom.com
 Dave Heald:   davehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Ba

RE: Conductive Coatings

[Nerad, Daren HS-SNS]

John,
I refuse to say "in another life" because I have only one life to go through
and learn through, taking credit for my successes and accepting
responsibility for my learning opportunities. (to me it's a Dilbert "pointy
haired manager" phrase(of course so is "learning opportunity" instead of
mistake)
(sorry for the soapbox)

 BUT I have had the opportunity to investigate both conductive materials
(composites) and conductive coatings.  We decided to use conductive coatings
on a computer system for a medical imaging system.  The product was mature
and only limited units were expected to be sold.  We did replace some of the
panels with metal ones (at a cost savings even over the unplated plastic!
management liked that).  A sprayed on copper paint was applied to the
plastic parts.  It worked very well!  At the joints, soft gaskets
(conductive fabric covered foam) were used (e.g. Schlegel (spelling?)).
This reduced wear (assembly / disassembly) concerns.  The unit went from
being a "comb generator" to compliant.  Adequate application of the coating
was achieved.  Vacuum deposition was considered but was too expensive and
may have had problems with the cavities in the existing plastic parts.
For the fairly small quantity of parts, this worked quite well.  IF we were
starting a project and could design the  plastic parts with a particular
process in mind, other processes (e.g. plating) might be a better choice. 
Refer to other comments on safety aspects.  I have seen problems with
coatings flaking off.  Also note my experience occurred ~ 5 years ago.
Seems recent to me but there may have been many improvements in the field
since then.
Good luck!
  
Daren A. Nerad
EMC Engineer
815.226.6123


-Original Message-
From: John Juhasz [mailto:jjuh...@fiberoptions.com]
Sent: Monday, August 20, 2001 1:30 PM
To: 'emc-p...@ieee.org'
Subject: Conductive Coatings




Greetings . . . 

Beginning to consider conductive coatings for EMC shielding.
To be used inside a plastic cover (material as yet unknown) in
a low power/voltage (SELV) application. 
This is unfamiliar territory.

I'm sure someone on this listserv has experience with these.
I know to at least consider shielding effectiveness, material
compatibility (plastic housing material to coating), and
end-user environment. What are some other critical criteria?

Thanks.

John A. Juhasz
Product Qualification &
Compliance Engineer

Fiber Options, Inc.
80 Orville Dr.
Suite 102
Bohemia, NY 11716  USA

Tel: 631-419-2324 (direct)
Fax: 631-567-8322
 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
No longer online until our new server is brought online and the old 
messages are imported into the new server.

RE: Conductive Coatings

[Chris Maxwell]

Hi John,

Read through some other responses.  I have had similar experiences to
those already mentioned.  One thing that I didn't see mentioned was the
alternative of electroless plating.   Electroless plating consists of
three major processes.

1.  The plastic parts are cleaned and "etched" by a solvent bath.

2.  The plastic parts are then put into a catalyst bath which coats them
uniformly with a reaction catalyst.

3.  The plastic parts are then put into a plating bath where the
catalyst reacts with the bath to plate solid metal onto the parts.
There are two sub-steps here.  One to plate Copper directly on the
plastic; and one to plate Nickel over the Copper (for durability and
corrosion resistance).

We had product samples put through this process back in 1996.  The
surface resistivity, uniformity and durability were excellent.
Electroless plating gets a uniform coverage of conductive material into
corners and small features of the plastic.   Our units were a split
plastic case with an overlapping center joint.  The plating could
withstand many mating/unmating cycles without degrading.

What was the drawback?  We didn't have enough volume to make it cost
effective.  The process requires masks to be made; and the masks aren't
cheap.  In short, the per part cost was comparable or even less than
conductive spray coating, but the tooling cost was higher (I seem to
remember around $6,000).   Another drawback is that the coating isn't as
good if you need to selectively coat parts (i.e. coat some areas while
leaving others bare).   

At the time, the process was called "Enshield" and it was being marketed
by Enthone,  New Haven, CT, PHONE:  203-934-8611, FAX:  203-937-1680.
Fair warning...these phone numbers are five years old.  I don't know if
they're still good, you may very well call them and get an answer from
Samuri Delicatessen.  

Chris



> -Original Message-
> From: John Juhasz [SMTP:jjuh...@fiberoptions.com]
> Sent: Monday, August 20, 2001 2:30 PM
> To:   'emc-p...@ieee.org'
> Subject:  Conductive Coatings
> 
> 
> 
> Greetings . . . 
> 
> Beginning to consider conductive coatings for EMC shielding.
> To be used inside a plastic cover (material as yet unknown) in
> a low power/voltage (SELV) application. 
> This is unfamiliar territory.
> 
> I'm sure someone on this listserv has experience with these.
> I know to at least consider shielding effectiveness, material
> compatibility (plastic housing material to coating), and
> end-user environment. What are some other critical criteria?
> 
> Thanks.
> 
> John A. Juhasz
> Product Qualification &
> Compliance Engineer
> 
> Fiber Options, Inc.
> 80 Orville Dr.
> Suite 102
> Bohemia, NY 11716  USA
> 
> Tel: 631-419-2324 (direct)
> Fax: 631-567-8322
>  
> 
> 
> 
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
> 
> Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/
> 
> To cancel your subscription, send mail to:
>  majord...@ieee.org
> with the single line:
>  unsubscribe emc-pstc
> 
> For help, send mail to the list administrators:
>  Michael Garretson:pstc_ad...@garretson.org
>  Dave Healddavehe...@mediaone.net
> 
> For policy questions, send mail to:
>  Richard Nute:   ri...@ieee.org
>  Jim Bacher: j.bac...@ieee.org
> 
> All emc-pstc postings are archived and searchable on the web at:
> http://www.rcic.com/  click on "Virtual Conference Hall,"
> 

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
No longer online until our new server is brought online and the old 
messages are imported into the new server.

RE: Conductive Coatings

[Stone, Richard A (Richard)]

Must worry about fire and electrical
enclosure requirments as well.

Depending on levels and components
inside these 94v rating will vary.
Richard,

-Original Message-
From: Doug McKean [mailto:dmck...@corp.auspex.com]
Sent: Monday, August 20, 2001 7:22 PM
To: EMC-PSTC Discussion Group
Subject: Re: Conductive Coatings



John, 

Yes.  I've done it.  But the info is dated a little. 

First, the plastic has to have it's own UL rating. 
For SELV this might involve V2 min. 
Not sure about that. 

Then, the mold house has to have it's own UL 
approval to do the molding. 

Then, the conductive coating must have it's own 
UL approval as an approved material. 

Then, the marriage of the coating and the coating 
has to have yet another UL approval. 

Then, the vendor who does the application of the 
coating to the plastic has to have yet another UL 
approval. 

Depending upon the coating being an oil base or 
water base, you'll get different ohm readings. 
The oil will be higher in general. 

Then, within the types of coating, be it oil or water 
based, there's differences in ohmage as well.  I got 
nickel which was good for 0.5 ohm with a 7mil layer 
I believe.  You can add more layers to lower the 
resistance.  Silver and copper coating will be lower 
in resistance for the same thickness. 

Then, the conductive coating can't be used as 
a primary ground. 

Conductive coatings are also good for only one 
time use essentially.  Removing and installing a 
cover several times with a conductive coating will 
jeopardize the integrity of the coating.  It'll flake or 
simply wear off.  So, it's best to use it with the 
understanding that once the cover is installed and 
fit in place, then it stays that way. 

I had very good results with it.  It was getting 
through the safety aspects that proved difficult. 
This directly impacts the search effort for a 
vendor to use up front before you even start 
using it. 

Make sure to consult your safety approvals engineer 
at whatever NRTL you're using to fill you in on all 
the details specific to safety. 

Regards,  Doug McKean 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
No longer online until our new server is brought online and the old 
messages are imported into the new server.

Re: Conductive Coatings

[Doug McKean]

John, 

Yes.  I've done it.  But the info is dated a little. 

First, the plastic has to have it's own UL rating. 
For SELV this might involve V2 min. 
Not sure about that. 

Then, the mold house has to have it's own UL 
approval to do the molding. 

Then, the conductive coating must have it's own 
UL approval as an approved material. 

Then, the marriage of the coating and the coating 
has to have yet another UL approval. 

Then, the vendor who does the application of the 
coating to the plastic has to have yet another UL 
approval. 

Depending upon the coating being an oil base or 
water base, you'll get different ohm readings. 
The oil will be higher in general. 

Then, within the types of coating, be it oil or water 
based, there's differences in ohmage as well.  I got 
nickel which was good for 0.5 ohm with a 7mil layer 
I believe.  You can add more layers to lower the 
resistance.  Silver and copper coating will be lower 
in resistance for the same thickness. 

Then, the conductive coating can't be used as 
a primary ground. 

Conductive coatings are also good for only one 
time use essentially.  Removing and installing a 
cover several times with a conductive coating will 
jeopardize the integrity of the coating.  It'll flake or 
simply wear off.  So, it's best to use it with the 
understanding that once the cover is installed and 
fit in place, then it stays that way. 

I had very good results with it.  It was getting 
through the safety aspects that proved difficult. 
This directly impacts the search effort for a 
vendor to use up front before you even start 
using it. 

Make sure to consult your safety approvals engineer 
at whatever NRTL you're using to fill you in on all 
the details specific to safety. 

Regards,  Doug McKean 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

RE: Conductive Coatings

[Gary McInturff]

Just a couple of quick things, and they are dated so maybe life has
changed for the better by now. 
One of the problems with the coatings originally was that the
sprayed versions did not stay adhered to the base plastic. That lead to a
requirement to age the product during the type certification, and to
control, not only the plastic but the guy applying the plastic, and the
spray material itself.
You want to find material that has very low bulk resistivity e.g. <
0.5 ohms.
You have to watch the tight corners and bends in the plastic, the
coating doesn't always wick into these spaces very well.
There are a lot of environmental concerns and safety concerns just
in the process of applying the coating. Some of the old methods included
sputtering which was pretty much like applying with an electric blow torch,
etc.
There is another version in which metal flakes are injected into the
plastic, it has some cosmetic concerns - the surface if fairly rough.
Probably of more concern is that the flakes wear out the molds much more
quickly.



-Original Message-
From: wo...@sensormatic.com [mailto:wo...@sensormatic.com]
Sent: Monday, August 20, 2001 12:13 PM
To: emc-p...@ieee.org
Subject: RE: Conductive Coatings



Other issues include recycling of materials per the proposed EU directive. 
See http://europa.eu.int/comm/enterprise/electr_equipment/eee/index.htm
<http://europa.eu.int/comm/enterprise/electr_equipment/eee/index.htm> 

Richard Woods

--
From:  John Juhasz [SMTP:jjuh...@fiberoptions.com]
Sent:  Monday, August 20, 2001 2:30 PM
To:  'emc-p...@ieee.org'
Subject:  Conductive Coatings



Greetings . . . 

Beginning to consider conductive coatings for EMC shielding.
To be used inside a plastic cover (material as yet unknown) in
a low power/voltage (SELV) application. 
This is unfamiliar territory.

I'm sure someone on this listserv has experience with these.
I know to at least consider shielding effectiveness, material
compatibility (plastic housing material to coating), and
end-user environment. What are some other critical criteria?

Thanks.

John A. Juhasz
Product Qualification &
Compliance Engineer

Fiber Options, Inc.
80 Orville Dr.
Suite 102
Bohemia, NY 11716  USA

Tel: 631-419-2324 (direct)
Fax: 631-567-8322
 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

Re: Conductive Coatings

[Ron Pickard]

Hi John,

In a past life, I had to deal with conductive coatings. In addition to the 
parameters you listed,
uniformity, integrity and durability of the coating were important. Uniformity 
was important because
the inside surface of the enclosure pieces were complicated (coating voids 
behind obstructions were
no-no's). Integrity and durability were important because the 2 major enclosure 
pieces had to slide
together (interlock) & then were secured with a couple of screws. For service, 
the enclosure had to
be diassembled/reassembled. We were also sensitive to wear and flaking of the 
coating on the
enclosure piece mating surfaces. As memory serves and as best that we could 
measure it, the coating
impedance was about 1-2ohm/sq. Also, we had to ensure a reliable low impedance 
connection from the
coating to the mains earth connection on all enclosure pieces. It is also worth 
noting here that
adding a metallic "inner skin" may compromise some safety clearances, so please 
keep that in mind.
You will also very likely increase the ESD discharge points by adding this 
coating.

Nowadays, other issues would likely come into play, such as hazardous material 
avoidance and
recyclibility, to name a couple.

I hope this helps. Good luck.

Best regards,

Ron Pickard
rpick...@hypercom.com





   
jjuh...@fiberoptions.co 
   
m  To: emc-p...@ieee.org
   
Sent by:   cc:  
   
owner-emc-pstc@majordomSubject: Conductive 
Coatings
o.ieee.org  
   

   

   
08/20/01 11:30 AM   
   
Please respond to   
   
jjuhasz 
   

   

   






Greetings . . .

Beginning to consider conductive coatings for EMC shielding.
To be used inside a plastic cover (material as yet unknown) in
a low power/voltage (SELV) application.
This is unfamiliar territory.

I'm sure someone on this listserv has experience with these.
I know to at least consider shielding effectiveness, material
compatibility (plastic housing material to coating), and
end-user environment. What are some other critical criteria?

Thanks.

John A. Juhasz
Product Qualification &
Compliance Engineer

Fiber Options, Inc.
80 Orville Dr.
Suite 102
Bohemia, NY 11716  USA

Tel: 631-419-2324 (direct)
Fax: 631-567-8322




---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"






---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on 

RE: Conductive Coatings

[WOODS]

Other issues include recycling of materials per the proposed EU directive. 
See http://europa.eu.int/comm/enterprise/electr_equipment/eee/index.htm
 

Richard Woods

--
From:  John Juhasz [SMTP:jjuh...@fiberoptions.com]
Sent:  Monday, August 20, 2001 2:30 PM
To:  'emc-p...@ieee.org'
Subject:  Conductive Coatings



Greetings . . . 

Beginning to consider conductive coatings for EMC shielding.
To be used inside a plastic cover (material as yet unknown) in
a low power/voltage (SELV) application. 
This is unfamiliar territory.

I'm sure someone on this listserv has experience with these.
I know to at least consider shielding effectiveness, material
compatibility (plastic housing material to coating), and
end-user environment. What are some other critical criteria?

Thanks.

John A. Juhasz
Product Qualification &
Compliance Engineer

Fiber Options, Inc.
80 Orville Dr.
Suite 102
Bohemia, NY 11716  USA

Tel: 631-419-2324 (direct)
Fax: 631-567-8322
 



---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

---
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/

To cancel your subscription, send mail to:
 majord...@ieee.org
with the single line:
 unsubscribe emc-pstc

For help, send mail to the list administrators:
 Michael Garretson:pstc_ad...@garretson.org
 Dave Healddavehe...@mediaone.net

For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org
 Jim Bacher: j.bac...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.rcic.com/  click on "Virtual Conference Hall,"

Re: conductive coatings

[Cortland Richmond]

Eric,

I'll chip in my two cents here, having had some experiences with conductive
coatings.  I've seen emission problems from products with both nickel
coatings and copper.  Problems have been due to incomplete coverage,
failure to fill details, and unauthorized vendor mechanical changes.

You can build testers for quick estimates how effective a coating is. My
favorite is two, one-turn, shielded loops with adjustable spacing. While
magnetic coupling is perhaps an unfair test for chassis shielding, I feel
it gives a good handle on how well a coating will prevent nearby
current-carrying conductors from generating external fields. (I've been
able to follow a computer's clock lines through the bottom of a chassis by
using a small -- 2mm -- loop; a result which rather startled the people who
saw it done.)  I generally "calibrate" a two-loop probe at a standard
distance, say, an inch or two cm, setting air as zero, and galvanized iron
as perfect. Because the coupling is rather localized, this will usually
find small defects in coverage which multiple resistance tests might miss.

The failures have mostly been related to quality of the coating, not
necessarily its material, however,some materials require different
techniques. Nickel has a relatively high resistivity and must be quite
thick for good shielding.  Copper can be MUCH thinner, but is, as a result,
more prone to failure to fill in chassis details than nickel, where
multiple passes are more likely to cover everything.  I had to press a
vendor to run three or four sprayer passes for a copper coating which
replaced a nickel one, and it took a good deal of cajoling to make it
happen.  However, once this was done, performance was better even that a
nickel one meeting emission requirements in use.

You will need to coordinate among mechanical, electrical and QC departments
when using coatings.  Too may details in the casting will result in a
hard-to-cover enclosure, and you will need to know here the electrical
design expects ground pits so these areas can be treated with special care.
 All these are possible,but (as with most other things in our business)
they are  most often done in  isolation, which makes our job more
difficult!


== Original Message Follows 

 >> Date:  24-Feb-98 13:08:27  MsgID: 1058-10464  ToID: 72146,373
From:  Eric Henning >INTERNET:henn...@fp.com
Subj:  conductive coatings
Chrg:  $0.00   Imp: Norm   Sens: StdReceipt: NoParts: 1

anybody have any opinions on conductive coatings on plastic for rfi/emi
protection?  we've been very successful  at designing our products to
be quiet and immune even in plastic boxes but i've been asked to 
look into conductive coatings for further protection.  i've ordered some
spray/brush on coatings but is it a waste of time? I was hoping to find
spray can samples but haven't,  anybody know of 
spray bomb coatings?  also looking into vacuum application. I guess
i'd like to try spray/brush stuff first just to see if it makes any
difference.

thanks

eric
henn...@fp.com

== End of Original Message =

Re: conductive coatings

[Doug McKean]

Yes Eric, 

I have worked with conductive coatings on plastic with 
no problems as long as some things are kept in mind - 

There's a whole UL thing to it that I can list 
if enough people want me to.  

The coatings cannot withstand repeated removal 
from the product. The coatings are very fragile. 
Follow the basic rule of - "install the cover 
only when you know it's not going to be removed". 

I looked into nickel, copper, and silver. It seemed 
that nickel was half as conductive as copper and 
silver was more than twice conductive as copper. 
Price seemed to follow suit also. 

Shielding effectiveness totally dependent upon 
how well your vendor can control the thickness. 
Stay below 1 ohms/sq.  I forget how many mils 
that works out to be for nickel. 7 mils maybe? 

Observe the type of emulsion used for the specific 
metal used. Nickel conductive coating is not 
nickel conductive coating. There are at least 
two out there I found - one's basically a water 
based paint, the other is a sort of oil based paint. 
The oil base is obviously less conductive and that 
translates to a thicker coating needed to be applied  
and that translates to more paint - more cost. 

Don't use it for primary ground obviously. 

I also looked into conductive plastic coatings. 
At the bottom of it all, conductive plastic was twice 
as expensive as plastic with conductive coating. 

Regards,  Doug 

--
> From: Eric Henning 
> To: emc-p...@ieee.org
> Subject: conductive coatings
> Date: Tuesday, February 24, 1998 3:53 PM
> 
> anybody have any opinions on conductive coatings on plastic for rfi/emi
> protection?  we've been very successful  at designing our products to
> be quiet and immune even in plastic boxes but i've been asked to 
> look into conductive coatings for further protection.  i've ordered some
> spray/brush on coatings but is it a waste of time? I was hoping to find
> spray can samples but haven't,  anybody know of 
> spray bomb coatings?  also looking into vacuum application. I guess
> i'd like to try spray/brush stuff first just to see if it makes any
> difference.
> 
> thanks
> 
> eric
> henn...@fp.com

RE: conductive coatings

[Mel Pedersen]

Say, Eric:  I just received my copy of the Jan/Feb issue of compliance 
engineering, and there is an article in it related to this issue that may 
interest you...do you get this magazine?  The article presents a mathematical 
solution to this problem, and it looks like it has some good references. I'd be 
glad to fax you a copy if you don't have it...

Mel PedersenMidcom, Inc.
Homologations Engineer Phone:  (605) 882-8535
mpeder...@midcom.anza.com  Fax:  (605) 886-6752


--
From:   Eric Henning[SMTP:henn...@fp.com]
Sent:   Tuesday, February 24, 1998 2:53 PM
To: emc-p...@ieee.org
Subject:conductive coatings

anybody have any opinions on conductive coatings on plastic for rfi/emi
protection?  we've been very successful  at designing our products to
be quiet and immune even in plastic boxes but i've been asked to 
look into conductive coatings for further protection.  i've ordered some
spray/brush on coatings but is it a waste of time? I was hoping to find
spray can samples but haven't,  anybody know of 
spray bomb coatings?  also looking into vacuum application. I guess
i'd like to try spray/brush stuff first just to see if it makes any
difference.

thanks

eric
henn...@fp.com

fwd: Re: conductive coatings

[Bailin Ma]

Good comment, Doug,

I talked to a vendor of conducting paint. Their Technical Service Manager 
Mattew Gochman at 800-336-1936 was very helpful.

Best Regards,   Barry Ma
-
Original Text
From: "Doug McKean" , on 2/24/98 4:02 PM:
To: 
Cc: 

Yes Eric, 

I have worked with conductive coatings on plastic with 
no problems as long as some things are kept in mind - 

There's a whole UL thing to it that I can list 
if enough people want me to.  

The coatings cannot withstand repeated removal 
from the product. The coatings are very fragile. 
Follow the basic rule of - "install the cover 
only when you know it's not going to be removed". 

I looked into nickel, copper, and silver. It seemed 
that nickel was half as conductive as copper and 
silver was more than twice conductive as copper. 
Price seemed to follow suit also. 

Shielding effectiveness totally dependent upon 
how well your vendor can control the thickness. 
Stay below 1 ohms/sq.  I forget how many mils 
that works out to be for nickel. 7 mils maybe? 

Observe the type of emulsion used for the specific 
metal used. Nickel conductive coating is not 
nickel conductive coating. There are at least 
two out there I found - one's basically a water 
based paint, the other is a sort of oil based paint. 
The oil base is obviously less conductive and that 
translates to a thicker coating needed to be applied  
and that translates to more paint - more cost. 

Don't use it for primary ground obviously. 

I also looked into conductive plastic coatings. 
At the bottom of it all, conductive plastic was twice 
as expensive as plastic with conductive coating. 

Regards,  Doug 

--
> From: Eric Henning 
> To: emc-p...@ieee.org
> Subject: conductive coatings
> Date: Tuesday, February 24, 1998 3:53 PM
> 
> anybody have any opinions on conductive coatings on plastic for rfi/emi
> protection?  we've been very successful  at designing our products to
> be quiet and immune even in plastic boxes but i've been asked to 
> look into conductive coatings for further protection.  i've ordered some
> spray/brush on coatings but is it a waste of time? I was hoping to find
> spray can samples but haven't,  anybody know of 
> spray bomb coatings?  also looking into vacuum application. I guess
> i'd like to try spray/brush stuff first just to see if it makes any
> difference.
> 
> thanks
> 
> eric
> henn...@fp.com

RE: conductive coatings

[Ing. Gert Gremmen]

hello eric and group,


This is technique,

The shielding properties for an enclosure depend of its round-going conduction 
properties in X-Y-Z direction. That's what we learned from Faraday's cage. If 
one applies a conductive coating, the success of this approach depends fully on 
the success of the full coverage inside. If FA you use to shell covers fixed 
together, big chances are that their will be partial or full interruptions in 
the conduction . The size of any interruption you may allow depends of the 
shielding you require and the wavelength of any to be shielded signal. In 
general use lambda divided by 40.

A shielding cover NEED NOT BE EARHTED, but it does no harm either. 

Conductive boxes are often used as both shielding and earth means.

The thickness of the coating has an impact on the attenuation of low frequency 
magnetic fields.
The thicker the better.

In general my conclusion is:  do not design to use coatings, use them only if 
it prevents failure of a test.

==
CE-test, qualified testing, 
Consultancy, Compliance tests for EMC and Electrical Safety
15 Great EMC-design tips available !
Visit our site  :  http://www.cetest.nl 
The Dutch Electronics Directory http://www.cetest.nl/electronics.htm
==


-Oorspronkelijk bericht-
Van:Eric Henning [SMTP:henn...@fp.com]
Verzonden:  dinsdag 24 februari 1998 21:53
Aan:emc-p...@ieee.org
Onderwerp:  conductive coatings

anybody have any opinions on conductive coatings on plastic for rfi/emi
protection?  we've been very successful  at designing our products to
be quiet and immune even in plastic boxes but i've been asked to 
look into conductive coatings for further protection.  i've ordered some
spray/brush on coatings but is it a waste of time? I was hoping to find
spray can samples but haven't,  anybody know of 
spray bomb coatings?  also looking into vacuum application. I guess
i'd like to try spray/brush stuff first just to see if it makes any
difference.

thanks

eric
henn...@fp.com

RE: Conductive coatings for enclosures/chassis

[Upson,Darrell]

Terry,

We use a process known as Electro Galvanizing (EZC) on our steel 
 enclosures.  It has very high conductivity and is cost effective.

Darrell Upson
Xerox ColorgrafX Systems
--
From: owner-emc-p...@mail.ieee.org
To: emc-p...@ieee.org
Cc: "Terry J. Meck"
Subject: Conductive coatings for enclosures/chassis
List-Post: emc-pstc@listserv.ieee.org
Date: Wednesday, September 25, 1996 2:55AM

Hello again:

Thanks for your comments on the PE Grounding!

This brings up amother question on protective coatings.

I have been promoting painted and masked conductive
coatings for the enclosures/chassis enclosures for
both EMC reasons and Class I safety reasons.   Typical
enclosures employed are required to be NEMA 12 in our
industrial applications. 

The mechanical engineers have been using clear
iridited aluminum with paint masking or clear zinc
cromate on the steel enclosures. The cost of masking
and the zinc is questioned.

Does anyone have some recommendations as to finishes
that are good conductive protective coatings, durable,
aesthetically pleasing and economical?

It would be nice to become something other then a pain in
future design reviews.

Thanks again for your time?


Best regards,
Terry J. Meck
Senior QA/Test Engineer
215-721-5280
tjm...@accusort.com
Accu-Sort Systems Inc. Telford, Pa USA

Re: Conductive coatings for enclosures/chassis

[Eric Petitpierre]

 


__ Reply Separator _
On 9/26 Terry Meck writes:

>Does anyone have some recommendations as to finishes
>that are good conductive protective coatings, durable,
>aesthetically pleasing and economical?

Don't have an answer to that, but if you find one, could you please post it?

Another thing to be careful about, as you may already know, is compatibility of 
metals.   You can have electrochemical reaction if you have a copper ground lug
tied directly to an aluminum chassis. ( Table J.1 and section 2.5.10 in UL 1950 
Third Edition explains this)  

We use a no-ox compound, spray, or brushed on, to provide a gas tight seal.

>It would be nice to become something other then a pain in
>future design reviews.


I can relate to that, and probably so can most other people in this group.
I try to think of it as helping to save somebody from getting burned or 
electrocuted.

All opinions are my own, not necessarily those of corporate.

Eric Petitpierre
Pulsecom
Herndon, VA
er...@pulse.com