Error Proofing with RFID

Modular assembly system

For a well-known customer from the semiconductor industry, the Gefasoft Automatisierung und Software GmbH has developed an automated loading and unloading system for the manufacturing of multi-chip modules. This system links numerous wire bonders and simultaneously handles quality control of the bonded chip modules. The machine has a modular design and consists of one loading and unloading module with three magazine handling stations, transfer paths on the wire bonder, as well as the transverse and reverse transport routes for the parts carrier. Before handlers transfer the processed chip modules to the good parts magazine, they are checked for correct wiring using RFID and image processing. A reject parts punch marks the defective parts with a hole on a determined position.

The parts carrier and the corresponding stations are equipped with the BL ident RFID system from Turck, which is connected to the plant’s control system via Profibus DP. Overall, six read and write points are currently integrated in the system: one on the ramp of the loading area, one on each in the maintenance positions in front of the three wire bonders, one with the transverse transport and one in front of the reject part punch. “In the system expansion phase that is now complete, we could also have handled the identification of the parts carrier with alternative technologies,” explains CEO Grünbauer, “but precisely because of the modularity and expansion capability of the system, we decided in favor of the RFID technology. It means that the system can be easily upgraded.”

Data carriers in metal

“We have a metal contact between the parts carrier and the data carrier. This should not actually be the case, but due to general construction conditions, the data carrier could not be mounted on its own nor positioned otherwise. And our tests showed that the Turck system had no problem with this issue, it functioned on the first go,” explains Müller happily. Turck offers special data carriers for installation on or in metal.

Documentation of the process steps

Gefasoft uses the RFID technology in order to document all process steps directly on the parts carrier. The first read-write location is located on the outlet of the loading machine. Here, the data carrier receives information as to whether all designated components were successfully mounted and can be further processed. If the four points in the parts carrier are properly filled, the content of the data carrier is added so it includes the processing release. Information concerning the successful or unsuccessful processing of each component is added on the following processing stations. Finally, on the last RFID station, the data is exported and the individual parts are forwarded by the operator either to the good parts magazine or the reject parts punch, depending on their classification on the data carrier. The production data is archived per batch in a report file.

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