PCBA Tech - SMT placement machine components and throwing materials

With the widespread application of SMT (surface mount technology) in electronic products, the key equipment in SMT production-the placement machine has also been rapidly developed, but in the use of the placement machine, some will inevitably happen Fault. How to eliminate these faults and ensure that the machine is in the best operating condition is an important task in the daily use and management of the placement machine. The following introduces some common faults and troubleshooting methods in the daily use of the placement machine.

Component picking error

The components are taken out from the packaging and tape by the high-speed moving placement head, and are placed on the circuit board. Several poor absorption failures will occur, such as not being picked up, and lost after being picked up. These failures will cause a large amount of component loss. Poor component pick-up is usually caused by the following reasons:

(1) The vacuum negative pressure is insufficient. When the component is sucked, the vacuum negative pressure should be above 53.33kPa, so that there is enough vacuum to suck the component. If the vacuum negative pressure is insufficient, it will not be able to provide enough suction to absorb the components. In use, check the vacuum negative pressure frequently and clean the suction nozzle regularly. At the same time, pay attention to the pollution of the vacuum filter element on each smt placement head. Its function is to filter the air source reaching the suction nozzle, and replace the polluted black ones to ensure the unblocked air flow.

(2) The suction nozzle is worn, and the suction nozzle is deformed, blocked, or damaged, resulting in insufficient air pressure, resulting in the inability to absorb the components. Therefore, the degree of wear of the suction nozzle should be checked regularly, and the serious ones should be replaced.

(3) The influence of the feeder, the feeder is poorly fed (the feeder gear is damaged), the material belt hole is not stuck on the feeder gear, there are foreign objects under the feeder, and the circlip is worn), resulting in Component attracts bias, stand-up or cannot absorb components, so it should be checked regularly, and if problems are found, they should be dealt with in time

(4) The influence of the suction height. The ideal suction height is when the suction nozzle touches the surface of the component and then press it down by 0.05mm. If the depth of the pressure is too large, the component will be pressed into the trough and cannot be taken. material. If the suction of a component is not good, the suction height can be adjusted slightly upwards

(5) Incoming material problems, some manufacturers produce chip component packaging with quality problems, such as large perforation pitch error, excessive adhesion between paper tape and plastic film, and too small trough size. Possible reasons for not being picked up

Throwing

Throwing refers to the loss of components in the placement position. The main reasons for it are as follows:

(1) The component thickness is set incorrectly. If the component thickness is thin, but the database is set thicker, then the nozzle will be put down when the component has not reached the pad position during placement, and the xy work of the PCB will be fixed. The platform is moving at high speed again, which causes flying parts due to inertia. Therefore, the component thickness must be set correctly.

(2) The PCB thickness is set incorrectly. If the actual thickness of the PCB is thin, but the database is thicker, the support pins will not be able to fully lift the PCB during the production process, and the component may be put down before reaching the pad position, Which leads to throwing materials.

(3) Reasons for PCB

1) PCB itself problems, PCB warpage exceeds the allowable error of the equipment,

2) The placement of support pins. When doing a double-sided mounting PCB, when doing the second side, the support pins are placed on the bottom components of the PCB, causing the PCB to warp upwards, or the support pins are not placed uniformly, and some parts of the PCB are not topped, causing the PCB to be incomplete Was jacked up.