Need something solid to seal it, Epoxy perhaps????

Hello All,

I want to make some of my components (on a PCB) consealed so that they are immovable, un-openable and if any one tries to "de-cure" it ... it (components) should get destroyed !!!

So, Do i Need a Expoxy based some thing? i dont know what it is called....

I did try using Silicone based RTV Sealent...Rubber... but it wont serve my purpose.

how can i achieve my objective ?.... there are loads of lights that have sealed "business heads" to keep their "Business" secret.... Many examples.... but i would like to quote Peak LED Solution's McKinley...

Its really nice idea to do this.... it first of all seals up the things, dose not let the moisture in... so protects it at the same time.

I also have a few questions regarding this "sealing" .... Lets say i seal out the components (mostly they are Chip's) ... and they do get hot.... will it be heat conductive ? .... what are the alternatives....

Also, the "curing" should be fast.... and at Room Temprature ... is it possible ? ....

I did search this forum about epoxy... but could not get satisfied results... even checked the dat2zip's epoxy question... (but it is an advanced stage i guess) ...

Please Guide Me....

Thanks & Regards,
ViReN

I can only tell you this, if someone wants to see your work, he will.

all the sealed heads you mention were opened and modded /ubbthreads/images/graemlins/smile.gif

Pablo

PEU /ubbthreads/images/graemlins/smile.gif thats true ... but there must be some way where i can seal up the things... and it would make harder for people (generally) to poke in to the things... not that the circuit that i am using is very precious... but to prevent tampering with the things... and to keep away bad practices.. like copying etc etc... i want to make the specific components sealed....

I will post the picture of what exactly i want to seal soon.

Thanks & Regards,
ViReN

Epoxy will be one of the tougher items to unhide, RTV/Silicone is easy to undo. The higher the Tg point of the epoxy, the tougher it will be to do. Still, its a simple matter for anyone that is experienced to do. I've even undone the ARC4, and certain measures were taken to make it non-functional when undone. As far as flashlights go, it was one of the tougher ones to undo, but that only increases the fun factor.

Another factor that makes it tougher is if it survives cyrogenic shock. As I recall, several Master Bond and EpoTek (epoxy technologies) formulations are made to withstand this.

Hi Viren,

Using epoxy that is the same color as your components would make it more difficult. You could also drop a layer of epoxy, then some metal shavings as filler, then more epoxy, etc.. I'd hate to be cutting into a mess like that, not knowing which metal bits are component leads and which are bogus.

Of course, don't forget to file off all those component part numbers and markings to make it even more of a pain.

Oh, and don't forget to kick me back my 5% royalties on any sales of the device where my ideas were used.

pb

Hi ViReN,

Epoxy is the usual solution for this, since it's extremely hard to destroy either chemically or mechanically without also destroying the components or the PCB (which usually also are embedded in/made of epoxy). Often, an opaque filler is added to the epoxy.

But if your components get hot, you must find another way (e.g. connect the to a heat sink that protrudes outside the epoxy).

Curing at RT is usually not a problem - fast is mostly a matter of how fast you can work and what temperature your parts can withstand. Epoxy hardens exothermally, i.e. it gets _hot_ - with a fast curing epoxy, you can melt the bottom out of your mixing beaker. Otherwise, I know about epoxies with curing times between 5 minutes and several hours. Or you might want to use UV curing epoxies.

Bye
Markus

Hi,

I think, to undo epoxy heat is applied ... is it the only method to undo ? if yes.. then... i think ... that the components inside it will also get damaged by application of heat.... isnt it ?

What is a cyrogenic shock ? ... I am a total novice & newbie when it comes to these things...

pbarrette has pointed out about using epoxy of same color as chips... great idea... i was also thinking of using a black colored epoxy .... and filing the component part numbers is ofcourse a normal practice that has been usually employed... but ofcourse.. i needed tougher measures to make things more difficult /ubbthreads/images/graemlins/smile.gif

Where can i get cheap epoxy that will do my job ?

-ViReN

Hello markus_i ,

Thanks for your response. I am looking at epoxy with an opaque filler, may be black in color.... the components dont get very hot ..normally up to 45-55 may be 60 - 65 Degree Celcius is a ultimate maximum... and they definately wont burn out as i am not doing any things that will make it *hot* ... using them in a normal way... at normal loads....

I need some thing that will cure in may be 2-5 minutes .... or even UV Curing will do (depends on how long it will take) ... may be 30 - 40 seconds after applying UV ?

Also, what kind of die should i use ? ... I am thinking of using a Plastic die... with one end open for filling up the epoxy ... and then i will let the plastic in there itself.... (this might prevent hassle of removing.. if it's difficult) .... I dont know.. and not sure about this either...

Can you also point me to some of the links / names who sell cheap epoxy .... & the fillers....

Thanks & Regards,
ViReN

About ten years ago I used to buy epoxy by the kilo can, the same shop that sell the epoxy also sells the colorants, fillers, etc. For filler I used a white powder, so that way I worked the epoxy with a spatula.

Pablo

Re: Need something solid to seal it, Epoxy perhaps

One of the most effective things to do is to contact a fabrication house to have a custom IC made. A non-standard package is harder to decode.

The reality is that a sufficiently determined company can reverse engineer your work. X-rays, microscopes and good engineers will all work against you.

Unless you've come up with a really unique circuit the chances are that people will not bother to steal your design. If it's that good, you should patent it.

Daniel

Re: Need something solid to seal it, Epoxy perhaps

hmm... thats true too... there are many many ways to look in to..if some one really has to...but for my purpose... i just want to make it difficult .... not very very difficult... so that normal attempts would be barred... if one can work that hard (like X-ray etc etc...) ... they would be spending much much less energy if they design the circuit themselves. ... and thats the idea what i was thinking of....

I think, by epoxying the things in to a container will ease my troubles...

I will be using a plastic container about .75 mm thick to surround the components... which will also include resistors and chip capacators.... the whole value of the circuit (by cost) is less than 3$ ...

and people will go to X-rays & microscopes.... will find themselves ashamed... & feel foolish... that they had discovered a rather simple circuits in the epoxy....after so much of efforts....

and for normal guys... who just want to copy things... they can do nothing but to destroy the circuit itself...

i have nothing to loose in either case... hopefully /ubbthreads/images/graemlins/smile.gif

PEU, NewBie, pbarrette, markus_i ,gadget_lover ... you guys have been very very helpful to me... and have enlightned my knowledge... my whole hearted thanks to you guys.

My next mission is now to look for the Epoxy's & Fillers & Colorent's ... and to come up with the names... and again ask for your reviews regarding which one would be a best solution. /ubbthreads/images/graemlins/smile.gif

If any one has any names / brands.. i would be glad to look in to them too....

Thanks once again....
ViReN

Re: Need something solid to seal it, Epoxy perhaps

Hi Viren,

What are you building here? Can you at least give us a hint as to what this circuit will do that it's worth going through this extra trouble?

pb

Re: Need something solid to seal it, Epoxy perhaps

Have you had a look at 3M's thermal potting compound? It is basically a black-dyed epoxy, I'm not sure about how tough it is.

Alternatively, try an opaque epoxy such as Eclectic Product's SuperWeld which is dielectric and thermally conductive. I potted a DB convertor in some of this and it is nearly impossible to unpot the convertor without destroying it.

Re: Need something solid to seal it, Epoxy perhaps

How about defacing the name/code whatever, of the IC you are using before/after you put it in?

Re: Need something solid to seal it, Epoxy perhaps

There's a good idea. Deface the chip code. Polish off the code printed on the IC, then stenscil on a code from a similar looking chip. Use a ztec part number if you have an intel chip, for instance.

This will confound people who try to duplicate the circuit and still let you service what you sell.

Daniel

Re: Need something solid to seal it, Epoxy perhaps

The heat necessary to remove the epoxy does not damage the components if done right.

Here is an example of one of the ARC4 boards that was potted in that black epoxy:



(Don't worry Peter Gransee, it was done out of curiousity instead of reverse engineering. I chose this board because it is an example and it doesn't reveal any of the heart of the design. I though was dismayed over the poor flow through of solder in the pads, and the lack of fillets on both sides. Some of the wires had solder less than half way through the board, which from what I've experienced, causes reliability issues in the pad, creating a stress point where the solder stops in the midway through the board, often cracking the "via" after repeated thermal cycles. Also, it appeared the soldering temperature seemed a bit low, as there was poor adhesion to the wires. You might consider obtaining Metcal stations to help with the soldering temperature issue on the leads. This would help with the flow through and the adhesion at the same time.)

Re: Need something solid to seal it, Epoxy perhaps

Hi... pbarrette,

It would be a second generation or perhaps a third generation board... similar tht is normally being used.. but much much more different in some ways...

If you see my technical abilities... they are ZERO /ubbthreads/images/graemlins/smile.gif but if you see the way i think, its different (slightly though) from others....

It could mean a totally new / revolutionary thing... (ok ok.. i will stop bragging / boasting /ubbthreads/images/graemlins/wink.gif )

just some thing simple ... a board.. that will perform similar function (but NOT SAME) to what all others do ....

Nothing great at all... and there is nothing for me to hide... just... that for a normal being .. i dont want to poke on and fiddle with the things... and thats my only motive....

Mr "NewBie" has proved .. that if it can be done... it can be 'un-done' too ... nothing's impossible...

be it timetravel itself /ubbthreads/images/graemlins/wink.gif

but thanks every one.. its really great to discuss the things out here...
i keep saying this.. because it in deed is /ubbthreads/images/graemlins/smile.gif

Thanks & Regards,
ViReN

Re: Need something solid to seal it, Epoxy perhaps

LOL ViReN!

You can also select fillers that make it more difficult, such as boron nitride, in addition to rather high thermal transfer, it dulls tools of folks attempting to cut it. GE sells the stuff in buckets/barrels. A cheap alternative is various ceramics, which GE also sells.

Oh, humm, just had an idea. Never tried it, so I'd not recommend it, but have you ever thought of common cement with an adhesion promoter? That would be a real pain to remove...

Re: Need something solid to seal it, Epoxy perhaps

if it has to be heat conductive, use Arctic Alumina Epoxy....

i agree woth Jarhead on Silicone - just use some solvent or melt it off like wax....

of course, you could get a company to make your circuit with BOB (Blobchip On Board) architecture.....

neg

Re: Need something solid to seal it, Epoxy perhaps

Newbie, how did you remove the expoxy from ARC4? What is the exact proccess with temp?

What is your recommended way to break free parts that have been potted?