Before the advent of circuit boards, circuit connections were made through point-to-point wiring. However, with the increasing lifespan of electronic products, circuit aging has become increasingly apparent. This is a serious issue of line reliability; line breakage can lead to open or short circuits at line nodes. To address these issues, new PCB manufacturing technologies have been adopted.

　　With the continuous development of technology, the types of PCBs have also become increasingly diverse. According to the number of sides and layers, PCBs can be classified as single-layer, double-layer, multi-layer, single-sided, and double-sided, etc. The manufacturing processes for different types of PCBs also vary; the more sides, the more complex the PCB manufacturing steps. The following are flowcharts for various types of PCB manufacturing:

　　 Complete PCB Manufacturing Process

　 　Step 1 in Making a PCB: Design

　　PCB design is a crucial step in the PCB production process, often referred to as PCB design or PCB layout. The circuit board should be strictly compatible with the components that will be mounted/soldered onto the board and the overall project requiring the PCB. Due to these requirements, designers typically use PCB design tools to create the PCB layout. The PCB design steps can be further divided into the following parts:

　　PCB Schematic: A schematic diagram showing the connections of components on the circuit board. It can be said that the drawing of the schematic is the focus of the circuit board manufacturing process, the lifeblood of the circuit board. The quality of the schematic is closely related to the quality of the project.

　　PCB Drawing: This is a basic installation diagram of electronic components. Those familiar with PCB boards may know that a PCB board is made by covering a metal foil on an underlying insulating board, then etching away the unnecessary parts of the metal foil. The remaining metal foil then serves as the connection for PCBA components, and components can now be assembled according to the markings on the PCB drawing.

　　BOM File: This is a procurement file. For turnkey projects, the procurement of PCBA components, surface mount processing, and soldering all require these files.

　　Component Package Library: The component prototype library used in the schematic diagram.

　　PCB Package Library: This refers to the external package library of chips, resistors, capacitors, etc., on the PCB board.

　　CAM File: This file refers to the Gerber and NC Drill files. All design software can export this file, mainly for use by PCB manufacturers.

　　Note: Before the PCB manufacturing process begins, the designer should inform their contract manufacturer of the version of the PCB design software used to design the circuit, as this helps avoid problems caused by discrepancies. Once the PCB design is approved for production, the designer can export the design in a format supported by their manufacturer. A commonly used file type is called a Gerber file.

　 　Step 2 in the PCB Manufacturing Process: CCL Manufacturing

　　Copper-clad laminate (CCL) is a substrate material that can be divided into rigid CCL and flexible CCL. CCL is a key material that determines the signal transmission speed, energy loss, and characteristic impedance in the circuit, playing a role of interconnection, insulation, and support in the PCB. The detailed process of CCL is: PP cutting → pre-stacking → combining → pressing → disassembling → cutting inspection → packaging → warehousing → shipping. As the core of the circuit board, CCL surface contamination with dust may lead to short circuits or open circuits in the final circuit, so a cleaning step needs to be added in the PCB process.

　　 Step 3 in the PCB Manufacturing Process: Inner Layer Routing

　　After cleaning the CCL, we need to apply a photosensitive film to the surface of the PCB substrate to prepare for subsequent image transfer. This film has the characteristic of curing when exposed to light. Therefore, we can use this film to form a protective film on the copper foil of the CCL.

　　After removing the photosensitive film, the hardened photoresist covers the copper we want to keep, and the CCL enters the next stage: removing the unwanted copper. Just as an alkaline solution removes the photoresist, stronger chemicals remove the excess copper. A copper solvent solution bath removes all exposed copper. Meanwhile, the required copper is well protected under the hardened photoresist layer.

　　Not all copper boards are the same. Some heavier circuit boards require a larger amount of copper solvent and different exposure times. In addition, heavier copper boards require special attention to track spacing. Most standard PCBs rely on similar specifications.

　 　Step 4 in the PCB Manufacturing Process: AOI Inspection

　　PCB testing includes various testing methods such as visual inspection, AOI optical inspection, electrical testing, and functional testing. Usually, AOI inspection is performed after SMT assembly, but in order to ensure the yield of the PCB, AOI testing is also required after the inner layer circuit process is completed. This is because once the circuit board enters the lamination process, even if errors are found in the inner layer, they cannot be modified. Therefore, after the CCL enters the AOI inspection equipment, the equipment scans it and transmits the data of the defective images to the VRS, and then a specialist is responsible for repair.

　　 Step 5 in the Formal PCB Production Process: Lamination

　　As the name suggests, lamination refers to bonding the various layers of the PCB together, connecting the outer layers with the inner layers. This process is divided into two steps: layering and bonding. This step is a real PCB manufacturing process, which means that the green board (or other color) we see is formed after lamination. The basic form of a PCB consists of a laminate, the core material of which is epoxy resin and fiberglass, also known as the substrate material. Copper-clad laminate is a specific type of laminate used in PCB production, as mentioned above. In this step, we need to use a new raw material - prepreg. This material has good insulation properties and can help bond the core board with the outer copper foil.

　　After the above steps are completed, the iron plate and pressure aluminum plate on the upper layer of the PCB are removed. At this time, both sides of the PCB will be covered with a layer of smooth copper foil, and the lamination process is completed. It should be noted that in addition to its pressure-bearing function, the aluminum plate also plays the role of isolating different PCBs and flattening the outer copper foil of the PCB.