SMT machine is a kind of precision instrument, which is equipped with a variety of sensors, such as pressure sensor, negative pressure sensor and position sensor. With the improvement of the intellectualized degree of the SMT machine, it can check the electrical performance of components and monitor the normal operation of the machine at all times. The more sensors are used, the higher the intelligent level of the SMT machine is. The functions of various sensors are described as follows.
(1) Pressure sensor of the placing machine
In the SMT machine, including various cylinders and vacuum generators, there are certain requirements on air pressure. When the pressure is lower than that required by the equipment, the machine cannot operate normally. The pressure sensor always monitors the pressure change, once abnormal, it will alarm in time to remind the operator to deal with it in time.
(2) Negative pressure sensor of the SMT machine
The nozzle of the SMT machine depends on the negative pressure suction component, which is composed of the negative pressure generator (jet vacuum generator) and the vacuum sensor. The negative pressure is not enough, will not absorb the components, the feeder has no components or components stuck in the material package can not be sucked up, the nozzle will not absorb the components, these situations will affect the normal work of the machine. The negative pressure sensor always monitors the change of negative pressure. When there is no suction or suction components, it can alarm in time to remind the operator to replace the feeder or check whether the suction nozzle negative pressure system is blocked.
(3) Position sensor of the placement machine
The transmission and positioning of printed board, including the count of PCB, the real-time detection of the motion of the paste head and the table, and the motion of the auxiliary mechanism have strict requirements on the position, which needs to be realized by various forms of position sensors.
(4) Image sensor of the patch machine
The real-time display of the working state of the SMT machine mainly uses CCD image sensor, which can collect a variety of required image signals, including PCB position, device size, and the computer analysis and processing, so that the SMT head to complete the adjustment and patch work.
(5) Laser sensor of the patch machine
Laser has been widely used in the SMT machine. It can help judge the coplane of the device pins. When the measured device runs to the monitoring position of the laser sensor, the laser beam irradiates to the IC pin and reflects to the laser reader. If the length of the reflected beam is the same as that of the emitted beam, then the device is coplanar; if not, the reflected light beam becomes longer due to the upturned pin, so that the laser sensor can identify the missing pin of the device
Sink. Also, the laser sensor can identify the height of the device, which can reduce lead time to production.
(6) Area sensor of the patch machine
In order to operate the patch head safely, a sensor is usually installed in the movement area of the patch head and photoelectric principle is used to monitor the running space to prevent damage caused by foreign objects.
(7) Attach the pressure sensor of the chip head
With the improvement of the patch speed and accuracy, the "suction and discharge force" of the patch head to attach the component on the PCB circuit board is more and more demanding, which is commonly referred to as the "Z-axis soft landing function". It is realized by the load characteristics of Hall pressure sensor and servo motor. When the component is placed on the PCB board, it will be shaken at the moment, and its shock power can be transmitted to the control system in time, and then fed back to the sticker head through the control system, so as to realize the Z-axis soft landing function. Have the function of the sticker head at work, give a person the feeling is smooth and light, if further observation, the two ends of the component immersed in the depth of the solder paste is roughly the same, which is to prevent the appearance of "monument" and other welding defects is also very favorable. Without a pressure sensor sticker head, there may be dislocation resulting in flying phenomenon.