Surface mount technology (SMT) is an advanced technology for mounting components on printed circuit boards (PCBs). Here is the detailed process of SMT assembly:

● Preparation:

Gather all the required components (e.g. integrated circuits, resistors, capacitors, etc.) and PCB boards.

Prepare SMT equipment, including placement machines, ovens, etc.

 

● Printing stencil:

Apply a layer of solder paste on the PCB board. The solder paste determines the exact position of the component on the PCB board.

● Component Positioning:

Using an SMT placement machine, the component is removed from the component library and precisely positioned in the appropriate location on the PCB. This process is usually automated.

 

● Soldering:

The PCB is fed into an oven, which is heated by hot air or infrared to melt the solder paste and fix the components on the PCB.

 

● SMD stage:

On the conveyor belt of the SMT equipment, the components are precisely placed on the solder paste under a high-speed conveyor.

● Reflow Soldering:

The PCB board passes through a temperature gradient region in the reflow oven. In the high temperature zone, the solder paste melts and completes the soldering, while in the lower temperature zone, the solder paste cools and solidifies.

 

● Quality Inspection:

Solder quality is checked using tools such as automated optical inspection (AOI) or X-ray inspection (X-ray) to ensure that components are correct and well soldered.

 

● Secondary operations:

Perform any manual or automated refill soldering, cleaning, or calibration work, if required.

 

● Functional Test:

Perform functional tests on completed PCBs to ensure they meet design requirements.

● Packaging and Shipping:

Packaging the completed PCBs into appropriate containers ready for shipment to the customer or to the next stage of manufacturing.

Please note that SMT assembly is a highly precise process that usually requires specialised equipment and training of experienced staff to ensure quality and efficiency. Also, the performance and process parameters of equipment such as placement machines and ovens need to be adjusted according to specific component and PCB board requirements.