Wednesday, November 16, 2005

Recently I complained about a low charging bag. The manufacturer came to me and he wanted to prove that the bags are suitable. He used a charged plate monitor. He charged it to 1000V. He connectted his wist strap to EPA ground, than he touched the plate with the bag. He measured the time taken for the voltage to decay to 100V. I think it's not an adequate method.

Whether on not it is an adequate method it is not a standard test method used in 61340-5-1 for demonstrating compliance of packaging. Actually it works by electrical conductivity and so is not even a test of "low charging" but is a sort of "charge decay" test of conduction properties. In the case of "low charging" there is no test method in 61340-5-1, neither is there any pass/fail criteria. But I would not use "low charging" bags for protection of ESDS, I would only use them to package documents or non-ESDS components to prevent them causing electrostatic fields.

For use to protect ESDS within the EPA under the 61340-5-1 standard the bags must be low charging AND either dissipative or conductive. They should therefore pass the criteria using a surface resistance measurement. If the bag does not pass this then it is not compliant with 61340-5-1.

To protect ESDS outside the EPA the total packaging solution (which could have many packaging types e.g. conductive box and dissipative foam) should also have shielding properties.

Wednesday, November 02, 2005

Documents innside ESD packaging



