Industrial image processing is the technological key to efficient, automated manufacturing processes in the photovoltaics industry.
Machine vision and automation for photovoltaics
The photovoltaics industry is a prime example of the success of industrial image processing in automation. One of the recurring tasks in this area is the precise position detection, for instance, for wafer handling and in silk-screen printing. Image processing systems ensure precise laser control in laser edge isolation or in microdrillings such as needed in modern wrap-through technology. Quick optical inspection systems identify material defects such as microcracks or chips at an early stage and are used to optimise production processes in a targeted manner.
In today’s photovoltaics production, automation solutions from Eckelmann are used in many manufacturing stages. Whether in laser edge isolation or in the inspection of solar wafers and modules, these systems improve the quality and efficiency of production processes.
Quick inspection of solar wafers and modules
The solar wafer production places high demands on quality control. E•SEE Waferinspect is a system for the inline inspection of monocrystalline and polycrystalline wafers which reliably identifies geometry and surface defects as well as errors in the crystalline structure.
Moreover, E•SEE Waferinspect precisely measures geometrical properties such as edge lengths, corner angles and bevel lengths of square and pseudo-square silicon wafers. Gauge capability can be verified semi-automatically by programmed sequences in the system.
Next to reliability and precision, the most captivating feature of the machine vision system is its cycle time. With a measuring and evaluation time of 0.8 s for two images per wafer, the system is capable of testing up to 3,600 wafers per hour, transport times included.
E•SEE Modulinspect was designed for the inspection of finished solar modules. Amongst other things, it identifies microcracks or interruptions in conducting paths.
Precise laser edge isolation
Our application for laser edge isolation is based on a line-scan camera which measures the wafer position and dimensions within microseconds. The laser is deflected by a galvo head (controlled by using the measurement data) and scribes very thin isolations onto the wafer.
A dense grid is lasered onto the wafer to calibrate laser and camera (grid calibration). From these data, the system calculates a so-called compensation diagram which is used for correcting errors that have occurred in controlling the laser deflection unit. Hence, there is no need for an elaborate calibration of the camera and laser coordinate system. Instead, the system is simply put into operation and can be recalibrated subsequent to maintenance.
As the image processing was taken into account right from the beginning, the system could be built in very compact dimensions. The general tendency that image processing systems are increasingly becoming integral components of machines becomes apparent in applications of this kind. As a consequence, the focus is shifting from simple quality control to inline process control.