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High Throughput , Despite 100% Inspection | Engineering Review

High Throughput , Despite 100% Inspection | Engineering Review

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The manufacturing process for solar cells consists of a multitude of individual steps. A weight check between each step ensures that only good wafers proceed to the next treat­ment. METTLER TOLEDO has the right products and the expertise to support machine builders in successfully applying weight based quality control for solar cells.

The transformation process from a block casted poly-crystalline silicon in­got to a solar cell consists of several in­dividual steps. It starts with cutting and shaping the ingots into wafers. Then the wafers have to pass through several etching, coating and printing processes until it is a solar cell with the capability to produce electricity. A strict quality control check at the end of each treat­ment ensures only good wafers proceed to the next production step.

 Weight-based quality control

Measuring the weight before and after each production step is a fast and reliable quality check. It allows for detecting de­viations in geometry, completeness and density of the wafer before surface treat­ment starts. Then the weight difference is used for checking results of etching, coating and printing. It requires weigh modules with repeatable precision be­tween 10 mg and 0.1 mg.

One weigh module for all steps

METTLER TOLEDO’s high-precision weigh modules comply with the requirements. They can reliably detect deviations of less than 1mg in a fraction of a second. The WMS104C is the most often used weigh module for quality control in silicium-based solar cell production. It has a read­ability of 0.1 mg and the repeatability of 0.2 mg. The software applies filter algo­rithms to measure correct and repeatable results despite of vibrations from ma­chines and drafts from the air condition­ing system. An incorporated calibration weight allows testing of correct function without the need to remove the hosting adapter for the wafer.

Fast communication

The fast interface sends 92 filtered and compensated weight values per second to the control system. The transmitted data can be converted to all common Fieldbus Systems if required.

Consultancy ensures successful implementation However, correct integration of weigh modules is key for the successful use of weighing technology in a solar wafer pro­duction process, because a number of challenging environmental effects have to be considered. Close cooperation dur­ing the design process between machine builders and the experts of METTLER TOLEDO ensures achievement of opti­mum performance.

Weight-based quality control is not limited to solar cells

Manufacturing of solar cells is not the only application for weight-based quality control. It can be applied to detect the smallest deviations in assembling, mold­ing, coating, etching and printing pro­cesses for many products. METTLER TOLEDO has its own direct service and sales force. Its experts are globally avail­able for consulting customers in correct integration of weigh modules into any kind of quality control applications.

Ask METTLER TOLEDO how weight-based quality-control can increase yield in your production.


METTLER TOLEDO is a leading global supplier of precision instruments and services. The Company is the world’s largest manufacturer and marketer of weighing instruments for use in laboratory, industrial and food retailing applications. METTLER TOLEDO also holds top-three market positions in several related analytical instruments and is a leading provider of automated chemistry systems used in drug and chemical compound discovery and development. In addition, the Company is the world’s largest manufacturer and marketer of metal detection and other end-of-line inspection systems used in production and packaging and holds a leading position in certain process analytics applications. Additional information about METTLER TOLEDO can be found at

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