Principles

Current spreading is a reconstruction of spreading currents, which are usually the real problematic element that cause ESD failures. Magnetic fields are measured in time domain while currents are injected to a fixed point of a DUT. The currents are then converted to surface current density through post-measurement processing, and finally, the current flow is presented as a video. This is for more visualization purposes rather than for quantitative analysis.
'Current Spreading Principles' video >>>

An ESD simulator can be a current injection device, but it has a notorious radiation issue, which can easily overpower the induced fields from the flowing current in a DUT. API uses a TLP as the current injection device. For more information about an ESD gun versus a TLP, click here.

Applications

● Identifying effective clamping device placement
● Performance comparison of clamping devices
● Identifying unintended current paths

Combining CS with the ESD scan can provide powerful insight to understand a DUT's behavior during ESD tests.

Required Equipment

● SmartScan-CS
● Probes
● TLP with a trigger signal capability
● Oscilloscope

Probes

EMI probes are used to measure the fields from the DUT. API's standard EMI probe for CS is Hx-2mm. Scanning is done for both X and Y directions separately, then combined together for magnitude.

TLP with a triggering signal capability

The field measurement and current injection have to be synchronized, and thus the TLP is equipped with a trigger signal port, which is a 40 dB attenuated TLP HV output.

Oscilloscope with minimum 2 GHz bandwidth and 20 GSamples / sec

The rise of the TLP is < 350 pSec, and 20 GSamples/sec sampling are enough for reconstructing the rising edge of the TLP output waveform. A list of oscilloscope families that API supports is shown below. API writes the driver when a specific oscilloscope driver is not readily available in SmartScan-CS.




● KeySight (Agilent) 54580A DSO
● KeySight (Agilent) 6000 DSO
● KeySight (Agilent) 9404A DSO
● Tektronix DSA70604
● Tektronix TDS6154
● Tektronix TDS7104
● Tektronix DPO7254
● LeCroy X Stream