The causes of the defects in the SMT Nozzle of the placement machine
The electronic components are taken out from the packaging tape by the high-speed moving patch head. During the process of mounting on the printed board, there are several faults such as unacceptable, lost after SMT , etc. These faults will cause a large number of faults. Component loss, according to our experience, component SMT is usually caused by the following reasons:
1) The vacuum negative pressure is insufficient. When the nozzle takes the component, a certain negative pressure is generated at the nozzle, and the component is adsorbed on the nozzle. It is determined that the nozzle picking component is abnormal. Generally, the negative pressure detecting mode is adopted, and the negative pressure sensor is used. When the detection value is within a certain range, the machine considers that the SMT is normal, otherwise it is considered that the SMT is bad. When the component is sucked, the vacuum negative pressure should be above 53.33 kPa, so that there is enough vacuum to absorb the component. If the vacuum negative pressure is insufficient, It is impossible to provide enough SMT SMT components. In use, we should always check the vacuum negative pressure and clean the nozzles regularly, and also pay attention to the pollution of the vacuum filter on each placement head. The gas source is filtered, and the blackening of the pollution should be replaced to ensure the smooth flow of air.
2) The nozzle is worn, the nozzle is deformed, blocked, damaged, and the air pressure is insufficient, resulting in the absorption of the component. Therefore, the degree of wear of the nozzle should be checked regularly, and the replacement should be severe. The Panasonic MCF nozzle Panasonic nozzle.
3) The influence of the feeder, the feeder is poorly fed (the feeder gear is damaged), the material hole is not stuck on the gear of the feeder, there is foreign matter under the feeder, the circlip wears), the pressure belt cover Plates, springs and other operating mechanisms produce deformation, rust damage, etc., resulting in components being deflected, slabs or absorbing devices, so they should be inspected regularly and problems should be dealt with in a timely manner to avoid a large amount of waste.
4) The influence of SMT nozzle height, the ideal SMT height is 0.05mm when the nozzle of the placement machine contacts the surface of the component. If the depth of the depression is too large, the component will be pressed into the trough instead. Unexpectedly. If the SMT condition of a component is not good, the SMT height can be adjusted slightly upwards, for example, 0.05mm. The author has encountered a bad SMT on all the components on a certain table during the actual work. In the case of the solution, the method of retrieving the height of the material in the system parameter is appropriately shifted up a little.
5) The problem of incoming materials, some manufacturers have the quality problems of the chip component packaging, such as the large pitch error of the perforation, the excessive adhesion between the paper tape and the plastic film, the size of the trough is too small, etc. Possible reasons for not getting up.