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PCB assembly process

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Published by: Keyou August 09,2019

A basic overview
The assembly process design of the printed circuit board assembly (PCBA), also known as the process path design.
The PCBA assembly process design determines the component layout (mounting) design on the front and back of the PCBA. In IPC-SM-782, the installation design of components on the front and back of the PCB is called assembly type design, and it is called product design in CISCO enterprise specification. The two are essentially the same, all based on process flow, yuan. The layout of the device on the front and back panels.

In fact, in the EDA design, the appropriate assembly process is determined according to the number of components and the package type, and then the layout design of the components according to the assembly process requirements, the core of which is "assembly process design".

We use the "Top component class / / Bottom component class" way to indicate the installation layout of components. The top surface corresponds to the top surface of the EDA design software, and is also the main assembly surface defined by IPC; the bottom surface corresponds to the Bottom surface in the EDA design software, and is also the auxiliary assembly surface defined by IPC.

 

            PCB assembly process

 

2. Design requirements
The recommended PCBA assembly process mainly includes the following processes.
1. Single-sided wave soldering process
The one-sided wave soldering process is suitable for both "Top Panel Mounted Components (THC) Layout" and "Top Mounted Components (THC) / / Surface Mount Components (SMD) Layout" designs.
1) Top THC layout
The top THC layout, that is, the design of the THC only on the top surface of the PCB.
Corresponding process path:
Top surface. Insert THC one wave soldering.
2) Top THC / / bottom SMD layout
The top surface THC//bottom SMD layout, that is, the THC is mounted on the top surface of the PCB, and the SMD design of the wave soldering is mounted on the bottom surface.
Corresponding process path:
a. The bottom surface. Spot red glue, the patch is cured;
b. Top surface. Insert THC;
c. The bottom surface. Wave soldering.
2. Single-sided reflow soldering process
The single-sided reflow soldering process is suitable for "top SMD layout", ie design where only SMD is mounted on the top surface.
3. Top surface reflow soldering, bottom full wave soldering process
Top reflow soldering, bottom full wave soldering process is suitable for “top SMD and THC// bottom without components or SMD layout. That is, only THC and SMD are installed on the top surface, and there is no component or wave soldering SMD design on the bottom surface. .

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