The Systematic Process of PCB Assembly

PCB’s or printed circuit boards are utilized in various electronic and mechanical devices. It allows a device or machine to function through the electrical connections and components attached on the printed wiring board. PCB assembly is a long and systematic process, and the following are the steps involved in it.


This is the first step in manufacturing PCB’s. It involves input and verification of data, and output of digital tools with the use of computer aided manufacturing (CAM) software.


A panel is a large board of grouped PCB’s for manufacturing. It typically has a single design but there are instances where a panel has mixed, multiple designs. The panel will be broken apart in a process called depaneling, and nowadays depaneling makes use of laser technology. Lasers can cut the panel without contact; thus, using them is more efficient as it decreases pressure on the fragile circuits.

3.Copper patterning


The pattern on the CAM system will be replicated on the copper foil with protective mask. Various patterning methods like silk screen printing, photoengraving, PCB milling, and laser resist ablation can be used depending on the volume of boards to be produced.

4.Subtractive, additive, semi-additive process

In the subtractive method, the copper is removed from the board that is entirely covered with copper. Only the desired copper pattern will be left. On the other hand, the additive and semi-additive method involve the use of film and mask. With the use of various chemical processes, the laminate will be coated with copper in the triggered areas, then the mask will be stripped.

5.Chemical etching

Makes use of chemicals like ferric chloride or ammonium per sulfate. Large scale production makes use of other chemical etching methods like splash etching and spray etching.

6.Inner layer inspection

An automatic optical inspection (AOI) that is done by scanning the board and comparing it with the digital image of the original data. This process is important; any mistake cannot be repaired or changed on the PCB assembly after lamination.


It involves the use of heat and pressure for a certain period that results into an inseparable piece.


It is the process of placing holes in the board. It makes use of automated drilling machines that accurately drill holes, but in cases where micro vias are required, manufacturers use laser.

9.Coating and solder masking

PCB’s are coated with solder, gold, or tin.

10.Legend printing

On one or both sides of the board, a legend must be printed to guide in the PCB assembly and testing.

11.Bare-board testing

Before other electronic components are placed on the board, it will be tested for any missing or wrong connection.

12.Solder paste printing 

With the use of stencil, the primary solder paste is printed on the PCB.

13.Component placement and attachment

The chips and other electronic components are placed and attached on the PCB.

14.Re flow

The PCB assembly will be placed on a re flow oven to melt the solder and fix the components on the board.

15.Conformal coating

For an additional protective layer, selective coating machines can precisely coat PCB’s.


Automated inspection for quality assurance is important. PCB manufacturers use automatic optical inspection (AOI) and automated x-ray inspection (AXI) to check flaws.


PBC’s will undergo this process if there are defects found. The board will be heated and components will be removed.


Once PCB’s passed inspection or after reworking is done, it will undergo several tests like functional test, in-circuit test, power-off testing, as well as quality control.

19.Protection and packaging 

Since PCB’s are sensitive to static it must be well-protected and packaged in anti-static bags before delivery.

Author Bio
The challenges can be easily addressed only if the chosen partner company for the PCB assembly has an untarnished reputation for expertise and experience. Our passion is to fulfill our customer’s requirements with an excellent response time.