Um fabricante de placas-mãe de PC utiliza a deteção de presença, imediatamente após a saída do forno de refusão, para desencadear uma operação subsequente. Um sensor indutivo de longa distância é montado à saída do forno, acima do tapete transportador e deteta cada uma das placas, à medida que estas saem do forno. O sistema de controlo do cliente recebe o sinal NPN à saída do sensor, iniciando a etapa seguinte do processo.
Valor acrescentado para o cliente
- Uninterrupted production as circuit-board detection is highly reliable
- Minimal replacement sensor costs as a result of sensor’s long service life
- Low risk of thermal or mechanical damage because of extended operating distance
Vantagens específicas do produto
- Desempenho do sensor não é afetado por temperaturas elevadas
- Condist® technology of Extra Distance family delivers best-in-class operating distances
- Extended sensing range ≤ 10mm
- Rugged inductive sensor with metal housing
Aplicação do cliente
During manufacture of PC motherboards, reflow soldering is used to secure components in place on printed circuit boards. Following assembly, boards are conveyed into a reflow oven, where the temperature increases progressively to achieve a predetermined thermal profile, melting the solder paste on the boards.
As each board leaves the oven, a sensor must trigger the customer’s control system and activate a transfer mechanism, moving the board automatically to the next process stage.
The ambient temperature immediately adjacent to the oven may reach 80°C (176°F), which has caused unacceptable rates of sensor failure in the past. Sensors must operate continuously in this environment with ultra-high reliability.
Extended sensing distances are highly desirable for this application as several types of motherboard, each with different component heights, pass through the oven. Long-distance sensing does not require the sensor to be positioned in close proximity to hot boards.
Solução no cliente
Contrinex inductive sensors from the Extra Distance family (500 series) are ideal for this application. Condist® technology delivers best-in-class operating distances and sensors have a continuous rating to 70°C (158°F). Trials confirmed highly stable performance even in the elevated ambient temperatures around the reflow oven. Vacuum-encapsulated electronics ensure excellent resistance to thermal shock and vibration.
Extra Distance sensors are mounted vertically on steel brackets attached to the exterior of the reflow ovens, and sense the presence of each motherboard as it passes beneath the sensing face. The operating distance is set at 10mm, eliminating the risk of collision with components on the board, and an M12-threaded metal housing allows easy positional adjustment when necessary.
Extra Distance sensors with an industry-standard NPN normally-open configuration connect with the customer’s control system via a flexible PVC sheathed cable. No additional electrical or mechanical protection is required in spite of the adverse operating conditions.
Previously, sensors from other manufacturers did not detect boards reliably and had unacceptably short service lives, causing frequent interruptions to production. Sensor replacement costs were excessive. Contrinex inductive sensors have been reliable and long-lived, providing a professional sensing solution with an attractive total cost of ownership.