PCB assembly process overview

The PCB assembly process mainly includes the following steps:

Component and material procurement: According to the requirements of the PCB and the bill of materials (BOM) provided by the buyer, the required components and materials are purchased. If some components are not available, they can be replaced with similar components with the buyer's consent. Design for manufacturability (DFM) is crucial, and experts will carefully check various documents to ensure that problems that may affect the smooth assembly of the PCB are found in the initial stage.

PCB manufacturing: Bare boards without any components installed are manufactured according to the buyer's requirements.

Solder paste application: Solder paste is applied to the surface area of the PCB where the components will be placed in the future by a machine with the help of a template. Solder paste is applied to the pads and holes for subsequent fixing and electrical connection of components.

Component placement (pick and place): After applying the solder paste, the machine is used to automatically pick up the components and accurately place them in the corresponding position. This process is transmitted to the machine through information, and the machine performs operations according to instructions to improve speed and accuracy.

Reflow soldering: After the components are in place, the PCB is sent to the reflow soldering furnace to melt the solder paste so that the components form a good electrical connection. The temperature of the soldering furnace is enough to melt the solder paste, thereby fixing the components and completing the electrical connection. After soldering, it needs to be cooled and tested to ensure quality.

Detection: Detection is a key step, including manual detection and machine detection, such as X-ray detection and automatic optical inspection (AOI). Although manual detection is not reliable, it can also find some problems; X-ray detection is effective and can penetrate multi-layer structures to detect internal problems.

The detailed process of PCB assembly process includes the following steps:

Cutting, filleting, and planing: Cut the original copper clad board into working boards.

Drilling: Drill the required holes on the PCB board.

Copper deposition: Form a copper layer in the hole after drilling to make the layers electrically connected.

Lamination: Press a layer of dry film on the circuit board for pattern transfer.

Exposure: Transfer the circuit pattern to the dry film through the exposure machine.

Development: Use developer to remove the unexposed part to form the circuit pattern.

Electroplating: Electroplating copper on the copper part to complete the circuit production.

Silkscreen: Mark the name and position box of each part on the circuit board.

Surface treatment: Protect the copper surface to prevent oxidation and ensure good solderability.