Anti-Static Conductive Box

[onemilimeter]

Today I received samples from Microchip. The samples were stored in a black plastic box (with "MICROPAK ANTISTATIC" words printed on the box). Inside the box there are two pieces of high-density foam. I can confirm that the foams are conductive. I wonder if the black plastic box itself is conductive (for antistatic). Anyone can help to confirm this? Many thanks.

[free_electron]

stick an ohmmeter to it. if its black plastic most likely you will read something in the order of a few tens of kiloohm.

[onemilimeter]

stick an ohmmeter to it. if its black plastic most likely you will read something in the order of a few tens of kiloohm.

I used a Fluke 12B multimeter to test the resistance between two points on the surface of the black plastic but the reading was "OL" (open circuit). But when the same multimeter was used to test the black foams which came inside the Microchip sample box, it recorded few kilo-ohm. What do you reckon?

[SeanB]

Static dissipative plastics typically have resitivities in the 10's of megohms per square. You need to use a meter capable of measuring gigohm resistors. Otherwise apply a high voltage to the one side and check if there is any current flow in the order of uA through it.

[Baliszoft]

I got lots of these microchip micropak antistatic boxes.

The foam inside measures around 1 MOhm per cm and the box itself is 100-200 kOhm per cm. For me.

[T4P]

Baliszoft, that's a bit odd.
On the foam i'm reading 5kohm/cm and the box is 0.22kohm/cm

[Baliszoft]

Baliszoft, that's a bit odd.
On the foam i'm reading 5kohm/cm and the box is 0.22kohm/cm

Well, re did my measurements. Depending on the pressure i applied on the probes, i could get down to ~20k on the box, but there are places where it is a lot higher (around the 200k). On the foam, i could get down to 0.6 MOhms with a lot of pressure (i got it out of the box, otherwise it can be easily punctured giving false reading (the resistance of the box)).

All in all it looks like to be antistatic.

[Sionyn]

they make green stickers to absorb moisture for shoe boxs (very hand to have in guitar case)

http://www.micropakltd.com/pdf/Micor-Pak%20Stickers%20-%20Instructions%20for%20use%20(Update).pdf

[onemilimeter]

Static dissipative plastics typically have resitivities in the 10's of megohms per square. You need to use a meter capable of measuring gigohm resistors. Otherwise apply a high voltage to the one side and check if there is any current flow in the order of uA through it.

I think you're right that my multimeter is not capable of doing the job. Will try to get a better multimeter from lab to test it. Thanks.

[onemilimeter]

I got lots of these microchip micropak antistatic boxes.

The foam inside measures around 1 MOhm per cm and the box itself is 100-200 kOhm per cm. For me.

Glad to know that the black plastic box is "conductive"... Thanks.

[NiHaoMike]

A simple way to detect very small currents with an ordinary multimeter is to simply set it to voltage mode. Then touch a 9V battery to the object to be tested and measure from another point on the object to the other terminal of the battery.

[T4P]

Well, re did my measurements. Depending on the pressure i applied on the probes, i could get down to ~20k on the box, but there are places where it is a lot higher (around the 200k). On the foam, i could get down to 0.6 MOhms with a lot of pressure (i got it out of the box, otherwise it can be easily punctured giving false reading (the resistance of the box)).

How much current can the U1252B source? IIRC my UT61E i was using for the test can source quite a lot of current compared to most measly DMMs

[onemilimeter]

Just watched the EEVBLOG #247 video. I still don't quite understand the ESD... Let's say there are two bags, denoted as Bag-A (which is non-antistatic) and Bag-B (which is antistatic, e.g. the pink bag shown in the video). If both bags are rubbed together, will charge build up on BOTH bags? Also, if Bag-A rubs against itself, will charge build up on Bag-A?

Thanks.