The goal of the classification test is to find a component’s failure threshold—the point at which an ESD pulse is too strong for it to survive. To do this, engineers use a methodical “staircase test” where the voltage is gradually increased. To ensure consistency, the entire test is performed at room temperature.

Here is a high-level overview of the procedure:

1. Prepare the Samples: A small batch of components, typically three devices, is selected for testing at a specific voltage level.
2. Apply Controlled Pulses: The test equipment applies a specific number of controlled zaps—one positive and one negative voltage pulse—to the pins of each component. To prevent device stress from rapid, repeated pulses, there is a minimum delay of 0.5 seconds between each zap.
3. Start Low and Go High: The test always begins at the lowest voltage level specified in the standard, which is 100 volts.
4. Check for Failure: After being zapped, each component is thoroughly tested to see if it still functions correctly. Failure is defined as the point when a part “no longer meets the device data sheet requirements.” In other words, if it doesn’t work as advertised, it has failed.
5. Increase the Voltage: If all the components in the sample survive the pulses, they are then subjected to the next higher voltage level in the standard. This process of zapping and checking is repeated until the components finally fail.

The result of this staircase test isn’t just a simple pass/fail; it provides enough information to assign the component a specific classification grade.