Dragon lair (antistatic)

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In another topic (holding the Dragon) Bloody-orc warned me that a plastic housing could get Staticly charged just after i built my own.

But most modern electronics are encased with plastic, and all the cases i have here (even all plastic PSU units) can be made static.
(this will be an absolute bomb to the pc modding scene :-) )

Atmel encases devices in plastics, don't they?

Mounting it on a piece of wood or a metal case isn't my style, so what's the sollution?

Maby a small piece of an antistatic bag between the pcb and the plastic housing?

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There was a thread about this appx a month ago in off-topic forum.
All I remember is that ABS is non-static.

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If you are talking about ABS or PVC, you're pretty safe. If you're talking about the type of plastic that celophain (spelling &, I can't remember its chemical name), you run a high risk of damaging your electronic device.

Devices enclosed in a plastic enclosure are typically safe. One thing to consider with a fully enclosed device is that, any static charge is built up on the outside of the case - not the inside. The inside of a plastic case remains statically neutral. That is, any charge that might be present on the inside of a plastic case is distributed evenly across the entire inside of the enclosure. Just as all charge external to the case is distributed evenly across the surface of the enclosure. It is the point of discharge where the damage ocurrs.

Typically, static electricity likes to discharge at areas that form a point, and not from larger surface areas. The external corners of any enclosures are far more prone to static discharge, then are the external surface areas. The internal surface areas, including the internal (inverse) corners are statically neutral and can't discharge to other areas of the internal enclosure.

When the case is open, say, for servicing, standard static practices need to be observed, as would normally be.

I use ABS plastic cases for a lot of electronic projects, and have never had any static related failures. In fact, I'm more liable to destroy my project because of my own stupidity, and not static discharge.

Edit:
Plexiglass sheeting is not a plastic that you would want to use as, it will hold a static charge. Lexan will be a much better choice as, it is not statically induced as Plexiglass

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

Last Edited: Sun. May 20, 2007 - 01:30 PM
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Lennart wrote:
There was a thread about this appx a month ago in off-topic forum.

Read something like that too, someone with a modified cd case.
Wasn't able to find the topic using google or the search function.

microcarl wrote:
If you are talking about ABS or PVC, you're pretty safe. If you're talking about the type of plastic that celophain (spelling &, I can't remember its chemical name), you run a high risk of damaging your electronic device.

Ah someone who has fought this battle before.

My casing that i made before all of this was an old electronics project casing, it's darkened see through plastic.
Could that be Cellophane?
(Googled it for spelling)

Last Edited: Sun. May 20, 2007 - 01:39 PM
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Maximilian wrote:
Lennart wrote:
There was a thread about this appx a month ago in off-topic forum.

Read something like that too, someone with a modified cd case.
Wasn't able to find the topic using google or the search function.

Yes! That type of plastic (A CD case) is not a good candidate for supporting electronic devices. It is the wrong plastic to use...

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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microcarl wrote:
Yes! That type of plastic (A CD case) is not a good candidate for supporting electronic devices. It is the wrong plastic to use...

Is See through darkened plastic always Cellophane?, is there any way to check?

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use the test I described in the other topic. Just rub that and see, if the static builds up or not. if it doesn't you are safe, if it does... you know what to do.
Also do the same test on a CD casing to see, what bad plastic should do ;) (or if your wool is woolen enough ;))

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bloody-orc wrote:
use the test I described in the other topic. Just rub that and see, if the static builds up or not. if it doesn't you are safe, if it does... you know what to do.
Also do the same test on a CD casing to see, what bad plastic should do ;) (or if your wool is woolen enough ;))

Verdict:
After yet again a thorough cleaning of my initial housing i threw it away because it seemed more prown to static buildup than other non see throug plastics.

Will convert a black plastic PSU case into the new dragonlair

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Maximilian wrote:
microcarl wrote:
Yes! That type of plastic (A CD case) is not a good candidate for supporting electronic devices. It is the wrong plastic to use...

Is See through darkened plastic always Cellophane?, is there any way to check?

I don't think that the color of the plastic determines the static suseptibility of plastic. After all, the color is only a dye mixed into the raw plastic.

The wool-rubbing test is one method to test for the static holding ability of plastic. There are static measuring devices that measure the suseptability of a material to hold a static charge. Using one of these instruments would be the correct way to determine a plastics usefullness for electronics applications. As to how cost effective it would be???

So, rubbing the plastic with wool and seeing if it moves two very small pieces (electrometer) of aluminum or, it it raises the hair (I don't have much hair, you might have to use one of your kids) on your head, would be at least some indication of the presence of static build up.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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What would be the difference anyway even if you'd have a metal surface, you'd still have the board floating in air? Why didn't atmel include good old HOLES in the board?

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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daqq wrote:
What would be the difference anyway even if you'd have a metal surface, you'd still have the board floating in air?

Probably none... The advantage to a metal plate, though, would be that you could properly ground it. I'm not sure how that would work with a plastic that inherently builds static charge.

daqq wrote:
Why didn't atmel include good old HOLES in the board?

I've asked myself that question, ever since I got my first STK500. And, I asked it again, after getting the Dragon.

While I understand that Atmel doesn't want to raise the cost of their development products with fancy cases, it costs incredably little to design suitable mounting holes into their caseless products.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Quote:
Probably none... The advantage to a metal plate, though, would be that you could properly ground it. I'm not sure how that would work with a plastic that inherently builds static charge.

Wouldnt a nice metal plate combined with a nice little dragon make a nice little capacitor?

BTW: My temporary solution: When I simply have the dragon in a box, I have it on the original conductive foam. When I want to use it I take it out of the box.

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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I've got the same setup as Daqq right now. Works est IMHO. When I get time after my finals, I'll try that rubber spacest thingy...

Ps Daqq shouldn't you be revising for your exams right now? they are like... TOMORROW! :D

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Quote:
Ps Daqq shouldn't you be revising for your exams right now? they are like... TOMORROW!

We all have to have our priorities. ;-) Nah, I got 1 from english, and 3 from literature. So i'm happy. The final exam from my specialization will be thursday.

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Good work. I do hope, that 1 = 5 in Other countries or A in US. (maximum)
Now if I could only get that chemistry sorted I could start enjoying the summer outside ;)

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bloody-orc: Good luck to you. 1 means best in slovakia, 5 means worst.

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Well done David :!: If the 3 for literature is sufficient then it wasn't too bad after all :)
Wish you good exams too Rain :!: Chemistry ... I remember that being a PITB for Dean too, ... so thumbs up ... soon exams will be over.

Nard

A GIF is worth a thousend words   She is called Sylvia (2018), lives at Mint18.3 https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Well, this is my current Dragon lair...

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There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Some (unsharp) pictures

The little pcb's are to connect the prototyping area quicly, just put the right one on and program

I hotglued the pcb while sill sitting on its antistatic foam, works like a charm!!

Later i'll add two transparent plastic rods for the leds

[/img]

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I can't remember whose web site gave me this tip but digikey part number SRH65TG-ND is an almost perfect fit for the Dragon. Four screws hold the board down and it would be a simple matter to make holes in the top of the case to allow plugging in the ISP leads; I'm just using half the case with rubber feet on the bottom.