Light emitting diodes are put to the test

The TeraLED is a novel tester for thermal and radiometric characterisation of light emitting diodes.

New from Micred, a member of the Flomerics Group, the TeraLED is a novel tester for thermal and radiometric characterisation of light emitting diodes.

The TeraLED system was demonstrated at the 2006 Semi-Therm Conference and show where it played a key part in Micred winning the Gold Award for Exhibitor Excellence.

Micred was selected for the award based on the votes of the delegates of the conference.

TeraLED was developed in response to demands from leading LED manufacturers and provides a complete solution for LED testing.

The TeraLED system can be used stand-alone for optical measurements or combined with Micred's T3Ster for a complete thermal and radiometric measurement.

A 300 mm diameter integrating sphere hosts a temperature stabilised device under test (DUT) fixture, the reference LED, and a radiometric detector or a detector head with a bank of different filters.

The temperature controlled environment combined with the high precision design of detectors and filters provides very accurate measurements.

The temperature stabilised LED fixture has a mounting area of 40 x 40mm and is capable of heatsinking up to 10W.

This Peltier-based device is controlled by the TeraLED electronics.

Its temperature can be programmed in the TeraLED software between 10 and 90C.

This fixture is attached to the DUT fixture port of the integrating sphere.

TeraLED incorporates photometric and radiometric measurement tools based on Inphora's high precision detectors and reference light sources.

The detector head is compatible with Inphora's IPR-DES series detector C25mm geometry and fits into the detector port of the TeraLED sphere using a C25/60 mm adapter.

A plain detector with uniform spectral response can be used as a radiometric detector or a filter bank may be inserted between the sphere and the detector head.

The filter bank is controlled via the electronics and can host up to six filters for measurement of radiometric and luminous fluxes and x and z chromaticity co-ordinates (tristimulus values).

The TeraLED software automates procedures like measurement of emitted flux (photometric or radiometric), efficiency or chromaticity co-ordinates as function of temperature and/or operating current.

The LED's electrical characteristics as well as thermal calibration diagrams are also measured.

Results are presented in form of plots.

The TeraLED control electronics interfaces all devices attached to the sphere with the measurement control computer.

TeraLED can be combined with Micred's T3Ster thermal transient measurement tester to provide highly accurate structural functions that provide detailed internal information for power LED packages revealing die-attach failures and other structural integrity problems.

When combined thermal and radiometric measurements are performed, the T3Ster provides power for the LED under test.

The T3Ster software performs the thermal measurements and the evaluation of the thermal transients while the measurement sequences required for the photometric and radiometric characterisation are performed by the TeraLED software.

The optical measurements are performed in thermal steady state.

Once they are completed, the LED under test is switched off and its cooling transient is measured by the T3Ster equipment.

The measured emitted optical power is then considered by the T3Ster software when it calculates the thermal metrics of the LED under test.

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