I am in something of a dispute with one of our suppliers, a large Japanese
manufacturer, of high value ESD sensitive assemblies.  They supply the
assembly in blue antistatic polythene bags (see below) with no secondary
protection.  I insist that they package in metallised ESD protective bags,
but with a negative response so far as they believe their packaging is adequate.

This is not an innocent issue as we have suffered several failures which
this manufacturer ascribes to ESD damage.  Being confident in our own
precautions I believe the delivery packaging could be the principal cause.

Their QA department's response is as follows:

    "I collected the physical properties of anti-static polyethylene 
     packaging for TFT and C-STN as follows.
     
     Items                            Standard
     Sort                  APTSTAT-Blue  50 micron m
     Material              (main resin) MITSUBISHI-Polyrthy LD F250
     (sub  resin) Anti-static resin
     Surface resistivity   10**9 to 10**12 Ohm
     
     We use this ESD packaging for not only all TFT products but also 
     all C-STN products.  
     By the way, surface resistivity of a metallised bag giving a Faraday 
     cage effect is about 10**11 Ohm.
     Therefore, we think this is not problem. 
     Thank you and Best Regards
     QA department, Japan"

Can anyone give me an authorative reference that I can use to decide this
argument one way or the other please. 

Merry Christmas

John Loveluck
Quality Manager
Tadpole Technology plc
[log in to unmask]

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