Principles

As an ESD simulator (a gun) discharges to a test point of a DUT, currents flow to chassis and internal PCB. The currents radiate E&M fields, which couple to components or traces in the PCB, inducing voltages or currents to the circuit. The induced voltages and currents can cause functional or unrecoverable failures to the circuit.

ESD scanning includes:
(1) emulating the fields that induce voltages or currents by magnetic field probes or electric field probes, respectively
(2) finding the sensitivity level at local areas of the circuit
(3) recording the responses of the DUT to the induced voltages or currents
Currents can be injected directly to the circuit by direct injection probes, and DUT response can be monitored as well.
'SmartScan ESD Scanner Introduction' >>>

Applications

● ESD failure debugging
● Quality inspection of functionally identical components or modules
● Qualification of components and modules for system level ESD

ESD Failure Debugging

ESD scan is an excellent tool to localize and debug IEC 61000-4-2 failures. Evaluation of countermeasures that are applied to modules is another area of application.

Quality inspection of functionally identical components or modules

The ESD scan is very effective for inspecting which supplier's part has the highest likelihood of causing ESD failures among multiple suppliers for functionally identical components.

Qualification of components and modules for system level ESD

It is more desirable to screen out potentially problematic IC's and modules before they are assembled into complete systems. The ESD scan can provide good information to determine the minimum ESD immunity level with an accumulated database by products.

"ANSI/ESD SP 14.5-2015, For electrostatic Discharge Sensitivity Testing - Near-Field Immunity Scanning - Component/Module/PCB Level" (published Sept. 2015) provides good guidelines.

Required Equipment

● SmartScan-ESD
● TLP (Transmission Line Pulser) as a disturbance source
● Probes
● Failure monitoring feature

TLP (Transmission Line Pulser)

The disturbance source of the ESD scan is a TLP with < 350 pSec rise time. For more information on backgrounds of selecting TLP as the source, refer to this paper in the Library.

Probes

ESD probes are designed in-house to have maximum E&M radiation. Several different sizes of magnetic field, electric field, and direct injection probes are available. Drawings below show concepts of four different types of probes.

Failure Detection Module

The automatic failure detection capability increases ESD scanning efficiency significantly because it enables the user to leave the scanner to run itself. It has the capability to monitor four analog and four digital outputs from a photo sensor and 1 kHz acoustic signals. It is equipped with one 120 ~ 240V AC relay and a NO/NC DC relay for DUT power cycle. It is software controlled. For more information about FD module, click here.

It is expected to provide a certain level of customization for automatic failure detection because failure definition is very different from product to product. Contact API for customization details.

Test Flow

1. Turn on the DUT
2. Move probe to the test position
3. Inject disturbance (field direct injection)
4. Monitor response of the DUT
5. If failed,
-- Power cycle the DUT
-- Lower the disturbance level (lower TLP voltage)
-- Repeat step #3
6. If not failed,
-- Move to next step
7. Move to next test point