PCBA Tech - SMT component placement accuracy and machine function

Use CAD tools to ensure the placement accuracy of PCBA components

There are many utility programs in PCB design CAD tools that can help designers accurately place their component footprints on the circuit board

Library tools: The importance of creating accurate components in CAD tools takes up space, but this step cannot be overstated. In short, the space occupied by poor components will not only cause unexpected manufacturing problems, but if the distance between components is too close or too far, it may also cause problems with part placement. Therefore, if possible, use automatic part generators and wizards. These tools are usually based on IPC specifications and will bring you heavy part creation work. Another great resource is to use online library services, which usually have complete resources for design tools that are already available for you to use.

Design rules: These often underutilized features may be of great help to PCB designers. They can not only set basic gaps, such as the spacing between pads, but also often have advanced functions. These can include defining different clearance values for component groups, areas, and sides of the circuit board. Also, make sure to use the cross-probing function of the design tool so that the components can be placed in the correct order according to the signal path defined in the schematic.

Placement function: Many tools have utilities that allow you to automate many component placement tasks, such as part alignment or copy placement patterns. These features can save you a lot of time and energy, and you should use them as much as possible.

3D: By using STEP models, many PCB design systems allow you to view the design in full 3D. Although the layout tool has the function of checking the clearance conflicts on the X-axis, Y-axis and Z-axis, it is very useful for designers to be able to see them when actually assembling parts. For example, design rules may allow manufacturing gaps between parts, but 3D allows you to see if there is enough space to insert connectors or manually rework parts.

In addition, PCB designers should ensure that the placement of components is consistent with the electrical, thermal, mechanical, and manufacturing specifications of the circuit board. Using the schematic as a road map for component placement is useful here, just like using various analysis tools to verify the accuracy of the final placement. Another useful trick is to fully understand the component placement rules before the layout begins, and this information can be obtained from the PCB contract manufacturer.

Function of SMT placement machine

As we all know, when using SMT placement machines, we also need to maintain them. So why do we need to keep it? How to maintain it? Let us understand according to SMT placement equipment:

1. Clean and lubricate the movable part of the bracket. During the long-term operation of the machine, due to improper environment, a large amount of dust will adhere to the moving parts (for example: screw, guide rail, sliding block, transmission belt, motor coupling, etc.). The purpose of maintenance is to prevent SMT machines from being maintained and cleaned in a timely and professional manner. If the machine is overloaded for a long time, it will inevitably affect the service life of the machine.

2. Clean and remove the dust and scale on the surface of the chip mounter and the chip mounter circuit board. The purpose of maintenance is to prevent poor heat dissipation inside the machine due to dust and scale, which may lead to overheating and burning of electrical components;

3. SMT machine maintenance can effectively reduce the speed of transmitting chips, reduce the number of alarms, improve production efficiency, and improve production quality

4. Disassemble and clean the internal air circuit, solenoid valve, vacuum generator, air cylinder, etc. SMT machine; the purpose of maintenance is to prevent if the oil in the air circuit cannot be cleaned and maintained in time, it will block the air circuit, resulting in high-volume components; in severe cases, the oil accumulated in the air circuit will corrode Internal sealing rings and components, such as solenoid valves, vacuum generators, cylinders, etc., which cause damage to the components and seriously affect the normal use of the machine;

5. After the warranty period and long-term operation, how to conduct a comprehensive and professional maintenance of the SMT placement machine? Some parts of the machine have hidden dangers (for example: machine circuit wear, cable rack wear, motor fixing screws and screw rods loose, some mechanical parts failure, wrong parameter settings, etc.). The purpose of this kind of maintenance is to avoid potential hazards, which will inevitably pose a threat to the normal production of the machine in the future. Therefore, it is necessary to carry out large-scale maintenance of the machine, timely check and find out the hidden dangers inside the machine, and solve them.

6. After a long time of operation, the relevant parts of the machine will be worn, deformed, and aged, and some of the placed parts will have deviations. The original parameters of the placement machine have not yet adapted to the current machine state, and have affected the installation accuracy of the machine. Therefore, the purpose of maintenance is to calibrate the machine regularly, so that the machine can be produced with high precision and improve the quality of PCBA products.