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| J.A. Legris... |
 Posted: Tue Nov 03, 2009 5:01 am |
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On Nov 3, 12:44 am, D from BC <myrealaddr... at (no spam) comic.com> wrote:
[quote]On Mon, 2 Nov 2009 20:51:05 -0800 (PST), Tim Williams
tmoran... at (no spam) gmail.com> wrote:
On Nov 2, 8:35 pm, MooseFET <kensm... at (no spam) rahul.net> wrote:
Make it all "firmware" in a FPGA and use a coin cell battery to keep
the FPGA always powered on. If they open it up poof goes the code.
Planned obsolescence, too. Good idea!
D: what about x-rays? Do they make lead oxide-filled epoxy? It's
pretty trivial to x-ray through potting otherwise. ;-)
Tim
Example:http://www.vidisco.com/images/full/app-ndt-Electronic-PCB-100.jpg
I can see the disc capacitors,resistors,jumpers and all traces.
But what an xray won't show chip functions and discrete part values.
imo ..encapsulation makes scope probing difficult.
[/quote]
I used to manufacture a product that was encapsulated and nobody ever
copied it. Then I stopped encapsulating, sales went up, and still
nobody copied it. Why? Because it used a micro. Last time I checked it
costs over $20K to read a locked micro. Also, the firmware was pretty
easy - no self-respecting programmer would pay $20K for someone else's
lousy object code, so they did it themselves and never got a faithful
copy.
If all you're protecting is a circuit design, don't count on epoxy
potting compound - it simply disintegrates under the heat and pressure
of an ordinary soldering iron, allowing you to drill down wherever you
need access. An x-ray would make the task almost routine.
More reasons for not encapsulating:
1) Honest dealing. Would you choose an encapsulated product over an
open one if there was no actual need for encapsulation? What are the
encapsulators hiding besides the functions?
2) A horrible mess. Epoxy is formulated to flow wherever it can, and
it does. Especially into DIP switches, connectors, and all over your
tools and work space.
3) Diagnostics and repair. How do you diagnose an encapsulated device
that fails. How do you repair it?
4) Expensive and time-consuming addtional steps to manufacture.
5) Environmentally unfriendly: for you, the customer and everyone
else.
--
Joe |
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| MooseFET... |
| Posted: Tue Nov 03, 2009 5:09 am |
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On Nov 2, 8:51 pm, Tim Williams <tmoran... at (no spam) gmail.com> wrote:
[quote]On Nov 2, 8:35 pm, MooseFET <kensm... at (no spam) rahul.net> wrote:
Make it all "firmware" in a FPGA and use a coin cell battery to keep
the FPGA always powered on. If they open it up poof goes the code.
Planned obsolescence, too. Good idea!
D: what about x-rays? Do they make lead oxide-filled epoxy? It's
pretty trivial to x-ray through potting otherwise. 
[/quote]
Nearly any large atom works. The trick would be to make the masking
material very nonuniform. Here's an idea for doing it:
Dip coat the board twice and let each dip dry completely.
Dip the PCB a 3rd time and then roll in random bits of metal from a
machine shop.
Dip the PCB and let it dry again.
Dip the PCB and then cover with bits of scrap wire.
Pot the whole mess. |
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| Dirk Bruere at NeoPax... |
| Posted: Tue Nov 03, 2009 8:09 am |
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Guest
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TTman wrote:
[quote]"D from BC" <myrealaddress at (no spam) comic.com> wrote in message
news:dddue5hrjdthg692kk7s5kgcti5kjkvfkr at (no spam) 4ax.com...
I'd like to pot my smt pcb with the nastiest sh*t possible to make it
hell for copy cats..
So far I've found:
http://www.mgchemicals.com/products/832ht.html
'Extremely difficult to remove - grants incredible technology
protection '
Besides epoxy.. Are there alternatives?
Araldaite 2014- grey epoxy. I use it, very, very good stuff !
Doesn't it shrink on curing, possibly damaging components?[/quote]
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show |
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| Spehro Pefhany... |
| Posted: Tue Nov 03, 2009 10:36 am |
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On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
<jalegris at (no spam) sympatico.ca> wrote:
[quote]On Nov 3, 12:44 am, D from BC <myrealaddr... at (no spam) comic.com> wrote:
On Mon, 2 Nov 2009 20:51:05 -0800 (PST), Tim Williams
tmoran... at (no spam) gmail.com> wrote:
On Nov 2, 8:35 pm, MooseFET <kensm... at (no spam) rahul.net> wrote:
Make it all "firmware" in a FPGA and use a coin cell battery to keep
the FPGA always powered on. If they open it up poof goes the code.
Planned obsolescence, too. Good idea!
D: what about x-rays? Do they make lead oxide-filled epoxy? It's
pretty trivial to x-ray through potting otherwise. ;-)
Tim
Example:http://www.vidisco.com/images/full/app-ndt-Electronic-PCB-100.jpg
I can see the disc capacitors,resistors,jumpers and all traces.
But what an xray won't show chip functions and discrete part values.
imo ..encapsulation makes scope probing difficult.
I used to manufacture a product that was encapsulated and nobody ever
copied it. Then I stopped encapsulating, sales went up, and still
nobody copied it. Why? Because it used a micro. Last time I checked it
costs over $20K to read a locked micro.
[/quote]
You didn't check overseas.
[quote]Also, the firmware was pretty
easy - no self-respecting programmer would pay $20K for someone else's
lousy object code, so they did it themselves and never got a faithful
copy.
[/quote]
Hubris is a great protection mechanism, at least in the West.
[quote]If all you're protecting is a circuit design, don't count on epoxy
potting compound - it simply disintegrates under the heat and pressure
of an ordinary soldering iron, allowing you to drill down wherever you
need access. An x-ray would make the task almost routine.
More reasons for not encapsulating:
1) Honest dealing. Would you choose an encapsulated product over an
open one if there was no actual need for encapsulation? What are the
encapsulators hiding besides the functions?
2) A horrible mess. Epoxy is formulated to flow wherever it can, and
it does. Especially into DIP switches, connectors, and all over your
tools and work space.
3) Diagnostics and repair. How do you diagnose an encapsulated device
that fails. How do you repair it?
4) Expensive and time-consuming addtional steps to manufacture.
5) Environmentally unfriendly: for you, the customer and everyone
else.
[/quote]
Good points all. |
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| baron... |
| Posted: Tue Nov 03, 2009 11:45 am |
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D from BC Inscribed thus:
[quote]On Mon, 02 Nov 2009 16:57:55 -0800, John Larkin
jjlarkin at (no spam) highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 02 Nov 2009 13:16:28 -0800, D from BC
myrealaddress at (no spam) comic.com> wrote:
I'd like to pot my smt pcb with the nastiest sh*t possible to make it
hell for copy cats..
So far I've found:
http://www.mgchemicals.com/products/832ht.html
'Extremely difficult to remove - grants incredible technology
protection '
Besides epoxy.. Are there alternatives?
ex: Very very hot melt? Low melting point glass?
D from BC
Amateur smps designer
British Columbia, Canada
Posted to sci.electronics.design
The disadvantages of potting generally far outweigh the likelihood
that someone will copy your design. And if they're determined, they
will anyhow.
John
Potting will make me feel good? :)
This might be ironic.
It's possible the first people to tear into the epoxy potting will not
be Asian copy cats but instead US patent owners who suspect their
patent is being used without permission.
[/quote]
You could additionally use a multi layer board with ground planes top &
bottom ! That could get around the Xray machine.
--
Best Regards:
Baron. |
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| legg... |
| Posted: Tue Nov 03, 2009 11:46 am |
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On Mon, 02 Nov 2009 15:39:24 -0800, D from BC
<myrealaddress at (no spam) comic.com> wrote:
[quote]On Mon, 2 Nov 2009 22:28:03 -0000, "TTman" <someone.pc at (no spam) ntlworld.com
wrote:
snip
While on wiki. I came across this tidbit...
http://en.wikipedia.org/wiki/Epoxy_resin
'Vinegar is an effective and safe solvent to clean up tools, brushes,
skin, and most surfaces contaminated with epoxy resin or hardener.'
Huh..didn't know that..
[/quote]
Don't count on it.....
RL |
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| J.A. Legris... |
| Posted: Tue Nov 03, 2009 4:04 pm |
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Guest
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On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe... at (no spam) InfiniteSeries.Org>
wrote:
[quote]On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
3) Diagnostics and repair. How do you diagnose an encapsulated device
that fails. How do you repair it?
Pitch and replace. Doh! Some products cost far more to service than
to simply replace, and that includes even many that are not ever
encapsulated.
[/quote]
Some of us are interested in knowing why their products fail. In fact,
I attribute my success, in part, to just such an attitude.
--
Joe |
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| J.A. Legris... |
| Posted: Tue Nov 03, 2009 4:22 pm |
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Guest
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On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe... at (no spam) InfiniteSeries.Org>
wrote:
[quote]On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
5) Environmentally unfriendly: for you, the customer and everyone
else.
Cured potting compounds pose no environmental threat (nearly all), and
even when uncured they only pose a threat to the environment if you or
another of your dopes gets the shit all over the place.
Use some brains.,
[/quote]
I did, which is why I no longer use potting compounds. The problem is
dopes like you who cannot reason beyond their next paycheck. The long-
term effects of most synthetic chemicals have never been
comprehensively assessed, so erring on the side of caution is the wise
thing to do.
--
Joe |
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| D from BC... |
| Posted: Tue Nov 03, 2009 4:49 pm |
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Guest
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On Mon, 02 Nov 2009 23:15:46 -0800, Archimedes' Lever
<OneBigLever at (no spam) InfiniteSeries.Org> wrote:
[quote]On Mon, 2 Nov 2009 22:03:41 -0800 (PST), Greegor <greegor47 at (no spam) gmail.com
wrote:
How do you like getting products made that way?
Unless YOU QUOTE who you are responding to, nobody will know who or
what the fuck you are talking about.
Not everyone reads or looks at there news the same way.
Relying on threaded views is retarded.
QUOTE what you are referring to. D'oh!
[/quote]
I smell a bot. |
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| D from BC... |
| Posted: Tue Nov 03, 2009 4:52 pm |
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Guest
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On Tue, 3 Nov 2009 08:54:25 -0000, "TTman" <someone.pc at (no spam) ntlworld.com>
wrote:
[quote]
Neato..
http://en.wikipedia.org/wiki/Araldite
'Highmark Manufacturing uses Araldite in the manufacture of advanced
ballistic protection body armor'
While on wiki. I came across this tidbit...
http://en.wikipedia.org/wiki/Epoxy_resin
'Vinegar is an effective and safe solvent to clean up tools, brushes,
skin, and most surfaces contaminated with epoxy resin or hardener.'
Huh..didn't know that..
It says vinegar will remove resin 'that is starting to harden'....
[/quote]
Sorry. I didn't mean to imply vinegar removes cured epoxy. |
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| Archimedes' Lever... |
| Posted: Tue Nov 03, 2009 7:31 pm |
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Guest
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On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
<jalegris at (no spam) sympatico.ca> wrote:
[quote]3) Diagnostics and repair. How do you diagnose an encapsulated device
that fails. How do you repair it?
[/quote]
Pitch and replace. Doh! Some products cost far more to service than
to simply replace, and that includes even many that are not ever
encapsulated. |
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| Archimedes' Lever... |
| Posted: Tue Nov 03, 2009 7:33 pm |
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Guest
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On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
<jalegris at (no spam) sympatico.ca> wrote:
[quote]5) Environmentally unfriendly: for you, the customer and everyone
else.
[/quote]
Cured potting compounds pose no environmental threat (nearly all), and
even when uncured they only pose a threat to the environment if you or
another of your dopes gets the shit all over the place.
Use some brains., |
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| D from BC... |
| Posted: Tue Nov 03, 2009 10:56 pm |
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On Tue, 3 Nov 2009 18:22:04 -0800 (PST), "J.A. Legris"
<jalegris at (no spam) sympatico.ca> wrote:
[quote]On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe... at (no spam) InfiniteSeries.Org
wrote:
On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
5) Environmentally unfriendly: for you, the customer and everyone
else.
Cured potting compounds pose no environmental threat (nearly all), and
even when uncured they only pose a threat to the environment if you or
another of your dopes gets the shit all over the place.
Use some brains.,
I did, which is why I no longer use potting compounds. The problem is
dopes like you who cannot reason beyond their next paycheck. The long-
term effects of most synthetic chemicals have never been
comprehensively assessed, so erring on the side of caution is the wise
thing to do.
[/quote]
I'm wondering about thermal expansion.
My 1"x1" pcb that I want to encapsulate will be in an environment
where the temp may swing from 22C to 70C daily.
I have no idea if an epoxy encapsulant will flex with heat and shear
forces will push on the tiny smt parts..
I'll try to find specs.
Perhaps testing in an environmental chamber is needed.
But I'm cheap, so I'll be using a light bulb in a box controlled by a
thermostat. |
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| MooseFET... |
| Posted: Wed Nov 04, 2009 4:31 am |
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Guest
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On Nov 3, 7:56 pm, D from BC <myrealaddr... at (no spam) comic.com> wrote:
[quote]On Tue, 3 Nov 2009 18:22:04 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe... at (no spam) InfiniteSeries.Org
wrote:
On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
5) Environmentally unfriendly: for you, the customer and everyone
else.
Cured potting compounds pose no environmental threat (nearly all), and
even when uncured they only pose a threat to the environment if you or
another of your dopes gets the shit all over the place.
Use some brains.,
I did, which is why I no longer use potting compounds. The problem is
dopes like you who cannot reason beyond their next paycheck. The long-
term effects of most synthetic chemicals have never been
comprehensively assessed, so erring on the side of caution is the wise
thing to do.
I'm wondering about thermal expansion.
[/quote]
You can find the thermal rate for most materials. There is likely to
be a temperature gradient but it will be smaller than the total swing.
[quote]My 1"x1" pcb that I want to encapsulate will be in an environment
where the temp may swing from 22C to 70C daily.
[/quote]
Smaller is better.
[quote]
I have no idea if an epoxy encapsulant will flex with heat and shear
forces will push on the tiny smt parts..
I'll try to find specs.
Perhaps testing in an environmental chamber is needed.
But I'm cheap, so I'll be using a light bulb in a box controlled by a
thermostat.
[/quote]
If you put a very flexible layer over the parts it will help.
Unfortunately it also provides the nice parting line to let the
pirates pop it apart along the boundary.
I have used a "light bulb" based heat box. Mine used power
resistors. You can get thermostats that can switch the load. A
couple of jugs of water in the hot box helps to hold the temperature
steady.
Run you freezer down as cold as it can get. Put the item in the
freezer and let it soak till it is all the way down. Once it is fully
cold move it to the hot box. leave it in the hot box for a day and
then move it back to the freezer.
This will quickly show you that the potting was a bad idea. |
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| Archimedes' Lever... |
| Posted: Wed Nov 04, 2009 7:01 am |
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Guest
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On Tue, 3 Nov 2009 18:04:35 -0800 (PST), "J.A. Legris"
<jalegris at (no spam) sympatico.ca> wrote:
[quote]On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe... at (no spam) InfiniteSeries.Org
wrote:
On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
jaleg... at (no spam) sympatico.ca> wrote:
3) Diagnostics and repair. How do you diagnose an encapsulated device
that fails. How do you repair it?
Pitch and replace. Doh! Some products cost far more to service than
to simply replace, and that includes even many that are not ever
encapsulated.
Some of us are interested in knowing why their products fail.
[/quote]
Some of us? You're a goddamned idiot for that snide remark. ALL of us
like just statistics.
[quote]In fact,
I attribute my success, in part, to just such an attitude.
[/quote]
Yes, but you apparently have no clue about hard potted devices.
If it is that small a device, you should already know all about every
failure mode there is for it, and that should be able to be determined
without examination in many cases. All you should need is your prior
knowledge of the circuit operation and the particulars of the failure.
If it is a power supply device and it is failing, you should not be
selling it as a product to begin with. A PROVEN design, will have all of
its failure modes documented. Any potted design should be a proven
design, especially if the potting is meant for IP security purposes.
Otherwise, a serviceable potting would be needed.
If you are selling hard potted products, you have already resolved to
full replacement upon failure.
Why a PS device would need IP security is the real question. Why this
dope thinks his supply circuit is so special that someone would be on his
heels to copy it is beyond me. If it is that revolutionary, he should
patent it, and SELL the design to a bigger player in the industry.
DUH. |
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