AOI and functional test for assembled LED PCBs Premiere for in-line automated LED Test Systems

Testsystem »LaserVision LED« von Prüftechnik Schneider & Koch

Test technology specialists Prüftechnik Schneider & Koch present a world first - the test system „LaserVision LED“ for 100 percent testing of LED modules during the running production process. It includes both AOI as well as complete electrical testing, and the result of the combination of the two provides optical measurements of the powered LEDs.

The new test system LaserVision LED automatically checks complete LED modules including components for mounting, solder joints, shorts, polarities, etc. In addition, live photometric tests are possible. In this case, a hitherto unseen combination of photometric measurements and camera inspection under running production conditions, is deployed. LED lights can be fully tested as end products and/or at different stages of their production.

Components with dimensions of up to 600 x 600 mm. which are also often manufactured for multiple applications, can be tested. This also covers typical ceiling lighting whereby the company also views manufacturing service providers and the automotive industry as clear target markets. Each test is performed at the individual LED level. During the inspection process, the LEDs on the test object are supplied with the necessary supply voltage. To determine the set-points test objects with typical values are recorded by means of photometric measurement in advance.

Calibration is carried out automatically during the next stage of development as part of the test system, and here the measured values are stored as parameters in the test program. This process can be repeated at any time (for example at the start of a new shift or when changing the product).

Thus aligned and set to production operation the camera system can now monitor the running manufacture of LEDs with regard to compliance with required tolerances and direct deviating devices to a repair station or reject them directly.
Since measurement is carried out during running manufacture by means of a camera test times can be implemented that are suitable for manufacturing speeds.

Test processes using light measurement tend, in general, be much higher and are therefore not really suitable for mass production. In practice for example, a 48-fold 100% test of an approx. A4 format can be achieved in just 20 seconds.

DUT specific interchangeable cartridges including an interface for the transfer of electrical signals are designed into the basic system with 64 contacts. However, this can be extended at full expansion up to 1536 pins. In the basic system, a DMM for measurement tasks and a Source Measurement Unit (SMU) are integrated for the testing power supply. Other measuring and stimuli-functions up to on-board parallel programming are possible.

By being able to use the system as a pure AOI system, a faster return on investment (ROI) is assured. Due to the high test cell inspection depth only a small production footprint is required. The standardized software solution for each test technology and the repair station concept ensures best possible performance and a competitive advantage for manufacturing companies.