What are the main sensors of the SMT machine?

The SMT machine is equivalent to an automated robot. All its actions are transmitted by sensors. The main brain determines what to do next. FASTPCBA will shares the types of sensors on the SMT machine.

SMT machine

SMT machine

1, Pressure sensor

The SMT machine, including various cylinders and vacuum generators, has certain requirements on air pressure. When the pressure is lower than the pressure required by the equipment, the machine cannot operate normally. The pressure sensor always monitors the pressure change. Once abnormal, it is timely alarm to remind the operator to deal with it in time.

2, Negative pressure sensor

The nozzle of the SMT machine is a vacuum suction component, which consists of a negative pressure generator (jet vacuum generator) and a vacuum sensor. If the negative pressure is not enough, the components will not be able to be sucked. When the feeder has no components or components stuck in the package and cannot be sucked up, the nozzle will not suck the components. These conditions will affect the normal operation of the machine. The negative pressure sensor always monitors the negative pressure change. When cannot suck the components, it can alarm in time to remind the operator to replace the feeder or check whether the suction vacuum system is blocked.

3, Position sensor

The transmission positioning of the printed board, including the counting of the PCB, the real-time detection of the SMT machine head and the work bench, the movement of the auxiliary mechanism, etc., all have strict requirements on the position, and these positions need to be realized by various forms of position sensors.


4, Image sensor

The real-time display of the working state of the placement machine mainly uses CCD image sensor, which can collect various required image signals, including PCB position, device size, and computer analysis and processing, so that the SMT machine head can be adjusted and mounted.


5, laser sensor

Lasers have been widely used in SMT machines to help determine the coplanarity of device pins. When the tested device runs to the monitoring position of the laser sensor, the beam emitted by the laser shines on the IC pin and is reflected to the laser reader. If the reflected beam length is the same as the emitted beam, the device is coplanar. When they are different, the reflected light beam becomes longer due to the upwarp of the pin, and the laser sensor recognizes that the device pin is defective. Similarly, the laser sensor also recognizes the height of the device, which reduces production lead times.


6, area sensor

When the placement machine is working, in order to operate the smt machine head safely, sensors are usually set in the movement area of the smt machine head, and the operating space is monitored by the photoelectric principle to prevent damage from external objects.


7, Component inspection

Inspection of components, including feeder feeding and component type and accuracy inspection. In the past, it was only used in high-end smt machines, and is now commonly used in general-purpose smt machines. It can effectively prevent components from being mislabeled,or not working properly.


8, SMT machine head pressure sensor

As the speed and accuracy of the patch improve, the requirement for the “sucking and releasing force” of the SMT head to place the component on the PCB is higher and higher, which is commonly referred to as the “Z-axis soft landing function”. It is realized by the load characteristics of the Hall pressure sensor and the servo motor. When the component is placed on the PCB, it will be shaken at an instant, and its vibration force can be transmitted to the control system in time, and then fed back to the smt machine head through the control of the control system, thereby realizing the Z-axis soft landing function. The SMT machine head with this function gives a feeling of smoothness and lightness when working. If it is further observed, the depth of the two ends of the component is almost the same in the solder paste, which is also very advantageous for preventing welding defects such as “tombstoning”.  If the smt machine head without a pressure sensor is easily to occur misplacing and flying phenomenon.

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