The solar branch is booming – and therefore also the production of photovoltaic systems.
The annual growth rate is calculated to be more than 40 percent by the International Energy Agency (IEA) for the globally installed photovoltaic output. However, for the manufacturers of silicon wafers - the basic elements for photovoltaic energy production - this also means: To keep up with this rapid growth rate, wafer production has to become ever more efficient.
Only a reliable process monitoring system enables the necessary leaps in efficiency for the production of wafers - starting from the cutting of the wafer from the silicon blocks, the so-called ingots. These ingots, made of highly pure silicon, are usually cut into thin slices – the wafers – using a wire-sawing process. The main criteria for the quality of these 0.18 to 0.28 mm thin slices is the force with which the wire saw is driven through the crystal ingots. If this force deviates from the optimal value – usually around 30 Newton – unclean cuts and material losses result.
Continuous monitoring of this critical sawing process using modern measurement technology helps to avoid production errors and material loss early on. A measurement device from HBM has proven itself for this task; its components – a force transducer and the industrial digiCLIP amplifier – are perfectly matched.
The transducer records the force acting on the silicon by the saw wire. digiCLIP continuously acquires these force signals and transfers them directly via Profibus-DP to the production control. In addition to acquiring the basic measurement data, digiCLIP also initially evaluates the deviations from the nominal force – and also transmits these to the superordinate production control. Thanks to the high transmission speed of the Profibus interfaces, error messages are sent in just a few milliseconds.
If the contact force of the saw deviates from the reference value, the production control fully automatically corrects the parameters for drive and control of the saw machine. This interplay between continuous force monitoring, error evaluation and feedback channel ensures an efficient early warning system in the production of wafers – and protects against costs and material losses. The individual advantages:
- Errors and operating problems during wafer sawing are detected more rapidly and can be corrected immediately.
- The continuous feedback and ensuring of sawing force enables efficient handling of the silicon ingot – and therefore minimum material loss during production.
- The quality of the finished wafers is significantly improved.
The perfectly matched components of this measurement chain in production ensures significant gains in efficiency for the production of wafers - and not just there. Wherever forces, torques or pressures need to be monitored, the industrial process monitoring systems from HBM provide reliable services for more safety and efficiency.