Press Release

Breakthrough in inspection of organic electronics

We are increasingly seeing demonstrations, samples and first products of printed electronic transistors and other products. Companies are focusing on yield improvements and a necessary part of this is adequate inspection of devices, preferably at high speed.

Normally this is done by shining a beam of light onto the surface, with the reflected image recorded by a camera, as shown on the left in Figure 1a below. However sometimes upon inspection, while the image would suggest there is no conductor present, conductive material may actually be there causing a short circuit. This occurs when the surface of the conductor is not flat and perpendicular to the camera (increasingly so as people work on flexible substrates), the incident light is reflected off at an angle and not detected by the camera, as seen by the image on the right in Figure 1b below.

Beltronics Inc., a Massachusetts based automated optical inspection company, has patented an inspection system to overcome this problem. Organic materials used in fabrication of organic electronic components slightly fluoresce. This fluorescence is created at the surface of the material and therefore unlike the incident light it is transmitted in all directions. Beltronics has devised a way to detect this slight fluorescence and therefore the presence of organic material, as shown in Figure 2. Metal conductors which do not fluoresce appear dark and the organic substrate appears bright independent of curvature, angle or flatness of the substrate. Organic material as thin as an incredible 410 angstroms has been detected using this technology.