• Desco
  • EMIT
  • ESD Systems.com
  • Menda Pump
  • Menda-ID
  • Protektive Pak
  • SCS
  • Smart Clock
  • Special Team
  • Statguard Flooring

ESD Superstore – Online Leader for ESD Solutions
000 Checkout

Added to your cart

You do not have any items in your shopping cart at this time.
View All cart items

  Shop from our other Desco
  Industries websites:

Desco Europe

Asia

Questions And Answers

# List All Questions Search List by Category
Question Currently, we put our PCB's in a static dissipative cassette holder and then transport them on a mobile cart.  We may go to using a conveyor / flow rack system which means pushing the cassettes over rollers using a ball bearing system (the cassettes would move about 10 feet).  Are there ESD issues to be concerned with, and if so, do we need to use a conductive roller / rack system that is groundable?  Derrick S.
Answer

Table 3 of ANSI/ESD S20.20-2007 has the required limit for Mobile Equipment (working surfaces), such as on carts, to be RTG (resistance to ground) less than 1 x 10E9 ohms. So cart should be grounded while being moved via a drag chain or conductive casters to an ESD Floor.

Compliance Verification ESD TR53 for carts should be measured for RTG using one 5# electrode. The objective of this periodic test procedure is to verify the resistance of the Cart grounding system (cart through grounded floor). A well-designed Cart compliance verification program not only tests the Cart, but also indicates the quality of the conductive path through the cart and floor grounding system.

Regarding your conveyor / flow rack system, the roller / rack system should be grounded. Per ANSI/ESD S20.20-1999 section 6.2.6.3. Automated Handlers “All conductive or static dissipative components of automated handling equipment should provide a continuous conductive path to ground, whether stationary or in motion. The equipment should minimize charge generation of the ESDS [ESD sensitive] items that are handled. Where insulative materials are necessary in the device path, they should be designed to minimize electric fields and the charge imparted to devices being handled.”

 
If you have found this Q/A useful, please rate it based on its helpfulness.
Rating Rating Rating Rating Rating
This question has been rated: 0%0%
(0% at 0 Ratings)