>On Mon, 02 Nov 2009 20:30:23 -0800, Archimedes' Lever ><OneBigLe...@InfiniteSeries.Org> wrote:
>>On Mon, 02 Nov 2009 17:37:39 -0800, D from BC <myrealaddr...@comic.com> >>wrote:
>>>I might try a solvent to smudge the ID on the IC.
>> Many these days are laser burned.
>> The Dremel grind will not hurt them.
>True.. >I do try to dodge making plastic dust when I can. >I don't like cleaning.
The high temp polymer dust is not the best stuff to be breathing either. I would not recommend doing any high speed power sanding on basically anything inside your house.
>I might even try melting the number with an old soldering tip.
It is not that kind of plastic. Use an engraving tool to gouge stripes into it and that will obscure the numbering.
> Dremel is probably the low cancer solution.
If it is laser etched, it is one of the only solutions. You have to move or remove media to remove etched info.
> Solvents make fumes and same goes for plastic melting.
There are not too many solvents that will attack the plastics most ICs are packaged in. The print used is pretty hardy stuff too. Usually an epoxy "ink".
>On Mon, 02 Nov 2009 20:37:14 -0800, Archimedes' Lever ><OneBigLe...@InfiniteSeries.Org> wrote:
>>On Mon, 02 Nov 2009 17:37:39 -0800, D from BC <myrealaddr...@comic.com> >>wrote:
>>>In addition to adhesion, the potting has to resist solvent/chemical >>>baths that pirates may use.
>> The stuff I am thinking of is a tough rubbery thing that can stop a >>knife point or a bullet, much less most solvents that you worry about >>that would melt polycarbonate, but not this. It is used by NASA. It is >>the ONLY encapsulant they have approved for HV space applications.
>Nasa stuff can be pricey. >Maybe I can get an Asian pirated copy of that rubbery stuff. :)
It is called "Conap" and there are no substitutes, as far as NASA is concerned, and it is VERY expensive, but I am sure there are plenty of good 'turgid' other brand polyurethane encapsulants out there.
>On Mon, 2 Nov 2009 20:51:05 -0800 (PST), Tim Williams ><tmoran...@gmail.com> wrote:
>>On Nov 2, 8:35 pm, MooseFET <kensm...@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. ;-)
> 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'....
TTman wrote: > "D from BC" <myrealaddr...@comic.com> wrote in message > news:dddue5hrjdthg692kk7s5kgcti5kjkvfkr@4ax.com... >> I'd like to pot my smt pcb with the nastiest sh*t possible to make it >> hell for copy cats..
> On Mon, 2 Nov 2009 20:51:05 -0800 (PST), Tim Williams
> <tmoran...@gmail.com> wrote: > >On Nov 2, 8:35 pm, MooseFET <kensm...@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. ;-)
> 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. 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.
<jaleg...@sympatico.ca> wrote: >On Nov 3, 12:44 am, D from BC <myrealaddr...@comic.com> wrote: >> On Mon, 2 Nov 2009 20:51:05 -0800 (PST), Tim Williams
>> <tmoran...@gmail.com> wrote: >> >On Nov 2, 8:35 pm, MooseFET <kensm...@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. ;-)
>> 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.
You didn't check overseas.
>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.
Hubris is a great protection mechanism, at least in the West.
>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.
>>>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.
You could additionally use a multi layer board with ground planes top & bottom ! That could get around the Xray machine.
<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.'
>> 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'....
Sorry. I didn't mean to imply vinegar removes cured epoxy.
On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
<jaleg...@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.
On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> wrote:
> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
> <jaleg...@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. In fact, I attribute my success, in part, to just such an attitude.
On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> wrote:
> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
> <jaleg...@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.
<jaleg...@sympatico.ca> wrote: >On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> >wrote: >> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
>> <jaleg...@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.
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.
On Tue, 3 Nov 2009 18:04:35 -0800 (PST), "J.A. Legris"
<jaleg...@sympatico.ca> wrote: >On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> >wrote: >> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
>> <jaleg...@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.
Some of us? You're a goddamned idiot for that snide remark. ALL of us like just statistics.
> In fact, >I attribute my success, in part, to just such an attitude.
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.
<jaleg...@sympatico.ca> wrote: >On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> >wrote: >> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
>> <jaleg...@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.
You're a goddamned retard.
> The long- >term effects of most synthetic chemicals have never been >comprehensively assessed,
Not with a dope like you at the wheel, but yes, there are long term studies, and there is long term knowledge in the industry, you stupid pussified twit.
> so erring on the side of caution is the wise >thing to do.
You're a goddamned long term stye on the face of intelligent men of the world. You meant to say "Being a PUSSY on the "side of caution" is a stupid way to achieve 'progress'".
You are probably so retarded that you embrace RoHS, and you think that metallic form lead is a problem for the environment.
If it were, the lead levels in water tables around lead mining and also around land fills and especially around decades old police shooting ranges would show higher numbers and they do NOT.
>>On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> >>wrote: >>> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
>>> <jaleg...@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.
>My 1"x1" pcb that I want to encapsulate will be in an environment >where the temp may swing from 22C to 70C daily.
The expansion numbers on potting are for what happens during curing.
>I have no idea if an epoxy encapsulant will flex with heat and shear >forces will push on the tiny smt parts..
Then conformally coat it BEFORE you pot it.
>I'll try to find specs.
They are, of course, available. Stycast is a common potting media.
>Perhaps testing in an environmental chamber is needed.
Not likely. A simple chamber with known temp is fine.
>But I'm cheap, so I'll be using a light bulb in a box controlled by a >thermostat.
> On Tue, 3 Nov 2009 18:22:04 -0800 (PST), "J.A. Legris"
> <jaleg...@sympatico.ca> wrote: > >On Nov 3, 7:33 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> > >wrote: > >> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
> >> <jaleg...@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.
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.
> My 1"x1" pcb that I want to encapsulate will be in an environment > where the temp may swing from 22C to 70C daily.
Smaller is better.
> 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.
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.
>>On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> >>wrote: >>> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
>>> <jaleg...@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.
> Some of us? You're a goddamned idiot for that snide remark. ALL of us >like just statistics.
>> In fact, >>I attribute my success, in part, to just such an attitude.
> 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
I've yet to find my design on the net nor in chip form. I figure the lazy cheap 'just in case' action is to pot the electronics in my product until it makes enough money for me to afford a patent guy to do all the patent searching, applying,patent write up,defending,offending and license granting...and maybe to run out to get coffee sometimes.
> >>On Nov 3, 7:31 pm, Archimedes' Lever <OneBigLe...@InfiniteSeries.Org> > >>wrote: > >>> On Tue, 3 Nov 2009 07:01:38 -0800 (PST), "J.A. Legris"
> >>> <jaleg...@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.
> > Some of us? You're a goddamned idiot for that snide remark. ALL of us > >like just statistics.
> >> In fact, > >>I attribute my success, in part, to just such an attitude.
> > 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
> I've yet to find my design on the net nor in chip form. > I figure the lazy cheap 'just in case' action is to pot the > electronics in my product until it makes enough money for me to afford > a patent guy to do all the patent searching, applying,patent write > up,defending,offending and license granting...and maybe to run out to > get coffee sometimes.
IIRC you should apply for the patent before you release the product (or even just keep it secret) or you may lose your rights. This presumes patenting the thing is a good idea in the first place - which is unlikely unless you have deep pockets.
On Wed, 4 Nov 2009 09:10:48 -0800 (PST), "J.A. Legris"
<jaleg...@sympatico.ca> wrote: >IIRC you should apply for the patent before you release the product >(or even just keep it secret) or you may lose your rights. This >presumes patenting the thing is a good idea in the first place - which >is unlikely unless you have deep pockets.
