Editor’s choice W
hether a smartphone, medical device or machine tool – almost every electrical device has a printed circuit board (PCB). However, these devices are getting
smaller, more efficient and faster, whereas the development cycles are becoming increasingly shorter. This also means that the boards must become significantly more powerful by using highly integrated components. Miniaturisation of switches and individual components, as well as ever increasing packing density, are essential elements to fulfill the required performance. In order to ensure that current – in the form of electrical energy signals or as information signals – easily flows through the components, exact positioning of electronic components is crucial. In PCB manufacturing, these must not only be in the right place but also on the right level in order to connect them properly. For smooth functioning, the components must not be tilted.
HIGH MEASURING REQUIREMENTS Sensors that inspect the position of highly- integrated components during production must overcome a series of challenges. Primarily, these include high speeds due to the highly dynamic production process, a small focus diameter because of extremely small components, and high spatial resolution due to minimal displacement changes that must be detected. The optoNCDT 1420 series of smart laser triangulation sensors from Micro-Epsilon is designed for high-tech applications. These laser sensors measure on a non-contact basis and do not affect the PCB or its highly-sensitive components. The non-contact measuring procedure enables the laser sensors to acquire and process the measurement values very quickly. The most important characteristics of laser triangulation sensors are their high performance, extremely compact design and reliable signal adjustment on changing surfaces, which ensures high precision results.
QUALITY CONTROL IN ELECTRONICS In quality control of PCB production, the sensors are placed in such a way that they measure the PCB from above. A traversing system guides them over the PCBs and its highly-integrated components. With a measuring rate up to 8 kHz, the sensors can detect dynamic processes directly in the production line. The compactness of the sensor (46 mm x 30 mm) and its integrated controller enable the sensor to be integrated in small installation spaces. The smallest possible diameter of the light spot is just 45 µm x 40 µm, which enables high precision measurements on fine IC pins as the light spot can be sharply focussed onto them.
Another critical factor for reliable measurements on PCBs is to use a measuring procedure that can measure different materials, from plastics to metals, which is why the laser triangulation principle is the correct choice. Laser triangulation sensors from Micro-Epsilon provide the innovative Auto Target Compensation (short: ATC) feature
12 October 2024 Instrumentation Monthly
SMART LASER SENSORS MEASURE EXTREMELY FINE DETAILS IN ELECTRONICS
PRODUCTION In PCB manufacturing, extremely high precision and high production speeds are required. Smart displacement sensors can be used in pick-and-place machines, where they perform reliable quality inspection at micrometer accuracies. In PCB production, the sensors can also inspect the position of integrated components and measure the scribe lines of PCB panels, says Glenn Wedgbrow, business development manager at Micro-Epsilon UK.
that enables the sensors to measure on permanently changing surfaces, from matt black to shiny and reflective targets, as well as from bright to dark. ATC ensures that the exposure time adapts to the conditions presented by the respective target object. To determine the
measurement values, the laser sensor projects a red laser point at a wavelength of 670 nm onto the target. The laser light is back-scattered in a certain reflection angle to hit the optical system of a CMOS line. With quickly changing objects from bright to dark, only a little light would reach the
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