Multi-Channel LED Tester for Colour and Intensity

Whether an LED lights up is easy to test. Whether it lights up in the right colour and at the right brightness is considerably more demanding – and that is exactly what decides whether an assembly is accepted by the customer or sent back. Our multi-channel LED testers check both, across the entire visible spectrum and on several LEDs at the same time.

What actually goes wrong in series testing

Failure modes with LEDs are rarely a total failure. More often they are parts from a different binning class that light up measurably brighter or darker, swapped colours on multi-colour indicators, reversed polarity, or a spread across the assembly that the end customer notices as an uneven display. A visual check finds some of these – and a different some from inspector to inspector.

A measuring test, by contrast, delivers figures that are comparable and can be documented. That is why repeatability in colour and intensity testing is the most important characteristic of these instruments.

Why multi-channel?

A typical assembly rarely carries just one or two LEDs. If they were tested one after another with a single sensor, the test time would set the cycle of the line. A multi-channel instrument measures several LEDs in the same pass – the test time therefore stays roughly constant, regardless of how many LEDs the assembly carries.

Two versions

• Version for in-circuit test – integrated into the existing ICT sequence via a serial interface; the measurement runs as part of the test program, without an additional work step
• Functional version with USB – works independently on a PC or at a functional test station and is suited to tests outside the ICT as well as to rework and sample testing

Which of the two is the right one depends on where in your process the LEDs are to be tested – in the in-circuit test that exists anyway, or at a station of its own.

Integration into your test fixture

The tester measures where the LED sits – which means the light pick-up has to be integrated into the test fixture. Since we build test fixtures ourselves, we can supply both from a single source: the fixture with the contacting, and the pick-up for the LED measurement in the right place. For existing fixtures we check whether the measurement can be retrofitted.