What are the ESD Classifications? A Look at the Charge Device Model

by Andy on November 7, 2011

Last week we took a look at the human body model ESD classification. While static discharge from the operator is a danger to ESD sensitive devices there are other concerns to keep in mind as well.

Charge Device Model Classifications

Charge device model (CDM) is concerned with making sure the device itself does not get charged. Even if the operator is grounded the device can still be damaged if it has a charge. ESD sensitive devices can become charged by rubbing against other materials such as their packaging. If a product gains a charge this way then it may be damaged when the operator touches it, allowing the device to discharge.

To protect against this damage it is important to make sure ESD sensitive products are stored properly. ESD-safe bags or bins can help prevent devices from being charged while being put in or removed from storage. This will help ensure your products are protected from discharge.

The classification system in the above chart is used to let an operator know how much voltage can discharge from a device before damage occurs. Products are normally classified in this system by charging the device and allowing it to discharge to a grounded object and checking to see how much charge is needed for the product to fail.

Circuit Board in ESD-Safe BagFor more information on charge device model ESD classification you can go to www.esda.org. They have several documents on how components are classified as well as information on ESD control programs.

Make sure to check back next Monday for the last article in our series on the machine model ESD classification system!



Read Part 1 of “What are the ESD Classifications? Human Body Model”

Read Part 3 of “What are the ESD Classifications? Machine Model”

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