Why You Should Stop Averaging Your Measurements

Learn why you should stop averaging your forward voltage measurements and how SpikeSafe current sources improve forward voltage measurement accuracy and reduce the cost of test in this helpful webinar.

For this demonstration, we used actual forward voltage measurement data from a leading Chinese manufacturer. The sample batch of measurements was taken using a typical industry setup: an Instrument Systems CAS 140 Spectrometer and a Keithley 2400 Series Source Measure Instrument. With this setup, eight to ten measurements need to be taken and averaged in order to reduce their 0.8% variation. Averaging leads to increased costs, increased time spent taking measurements and masked operator or instrument measurement errors.

Watch this video to see exactly how upgrading to a SpikeSafe Performance Series Current Source or Pulse Source Measure Unit can save you from having to regularly perform the costly task of averaging measurements and make improvements to your Vf measurement accuracy.

The Problem with Averaging Forward Voltage Measurements

Commonly used source/measure units produce varied measurements that require averaging to be useful. This raises the cost of measurements and adds additional risk to the production process as it can mask both operator and equipment errors.

The following graph shows one manufacturer’s measurements taken using a Keithley 2401 unit and a CAS-140 spectrometer.

Measurements taken using a Keithley 2401 and a CAS-140 spectrometer.

The original measurements (bright orange line) vary by about 0.8% which is significant when testing the flux output of a production LED. In order for these measurements to be usable, the manufacturer had to average them (dark line).

This same manufacturer swapped out their Keithley unit for a SpikeSafe™ Performance Series Current Source and took the same measurements using the SpikeSafe and CAS-140.

Keithley measurements (orange) versus SpikeSafe measurements (blue) .

As you can see in the overlaid graph, the SpikeSafe produced much more consistent measurements with only 0.04% measurement variation.

Improve Forward Voltage Measurement Accuracy by Switching to SpikeSafe

CAS-140 + Source/MeasureCAS-140 + SpikeSafe
Measurements per DUT101
DUTs per week1,0001,000
Total measurements required10,0001,000
Measurement variation0.8%0.04%

The Bottom Line

By switching to a Performance Series Current Source, this manufacturer could go from taking 10 measurements per DUT to taking just 1.

The immediate benefits of this were as follows.

  1. Increase capacity without increasing labor cost
  2. Increase capacity without significant investment
  3. Increase yield with reduced measurement variation

Contact us today to see how you can benefit from switching to SpikeSafe.