Double sheet detection of wafers

Wafers, used for printed circuit boards or semi-conductors, can get stuck to each other easily and it is therefore useful to perform a double sheet detection with ultrasonic sensors.
wafer double-sheet detection

Wafers are used for the production of printed circuit boards, semi-conductors, solar panels, etc. The wafers are light and ultra-thin and can easily stick to each other during various steps within the process. Think of the cleaning process or moving the wafers with a vacuum gripper. This creates stacked wafers, or double sheet. The wafers are often detected at a high speed during production, as are any stuck wafers. This increases the risk of breaking these wafers or damaging other wafers. Resulting in having to stop production and unnecessary costs. Therefore the double sheet wafers need to be detected before moving or further processing.

Due to innovation, there are more and more types of wafers, such as different colors, materials and structure. This presents challenges in the detection of a double sheet. In order to limit this impact of the variation of materials, we opt for ultrasonic sensors to detect the double sheet, whereby these variations do not form any limitations for the detection.

dbk+4 double sheet detection sensors on wafers

The dbk+4 series from microsonic are the ideal double-sheet detection sensors. The automatic teach-in function ensures that the sensor itself selects the correct settings. The teach-in also makes it possible to detect wafers of different thicknesses during the process with the same sensor. A teach-in on another (thicker or thinner) wafer is not necessary, the sensor does this autonomously.

For reliable and accurate detection of the double sheets, the dbk+4 sensors must be mounted at a specific angle of inclination to the continuous material. This differs per material in which angle this is, but in the case of wafer detection this is an inclination angle (α) of 11° to 27°.

The dbk+4 series also offers the choice of an M12 or M18 variant, the availability of a separate controller and the option of an angled version. Furthermore, these sensors are equipped with a PNP or NPN (NO or NC) output and a 2 m. fixed cable.

Menno Reijnders

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