Have you ever wondered how are PCB boards made? We all have encountered at least one small board with a lot of electrical equipment assembled in a complex. They have seen some inside broken Electrical equipment, from smartphones and televisions to simple machinery like a remote controller. These boards are called PCBs or Printed Circuit Boards.
How Are PCB Boards Made?
These PCB are like the backbone of electrical engineering and manufacturing electronics. These boards provide structural and electrical support to small electrical components like resistors and capacitors etc, in heavy electronics.
History of PCBs
The traces of PCBs can be seen to the 1900s. That era was the beginning of the initial connections of electrical connections with wires, connectors, and screws. It was during the time of World War II when the demand to make better, more reliable radio and communication equipment was raging. This demand led to starting of absolute PCB construction. However, during the late 1940s, PCBs were available for commercial purposes. In the 1950s, the introduction of techniques like the photo-engraving process advanced older versions of PCB manufacturing. This technique allowed the processing of better light-sensitive material etching. In the early 1950s, companies like Motorola were one of the first to commercialize these boards and started using them for consumer electronics like general Radio. It was until the very late 60s that wide spectrum use of PCB was noticed. PCBs were widely used in Television and high-fi industries. During the 60s and 70s, using CADs (Computer Aided Designs) helped advance PCB designing. This CAD software made PCB designing more efficient and time-saving.
The Materials Used in PCB Board Manufacturing
To make PCB efficient and reliable, a broad variety of materials are used. But these materials can generally be broken down into a few categories: Conducting Material: The conducting materials are usually used to make conducting traces on the board. Since copper is conducting, it is heavily used in these tracing techniques. Usually, electroplating is used to deposit this copper on the base of the board. Copper also gives scope to cut down production costs with efficient conductivity. Substrate Material: The substrate material is the base material in a PCB. This makes up most of the board. On this substrate material, all the conducting lines and traces are deposited. Materials like fiberglass-reinforced epoxy resins, ceramics, and polyamide are used. Generally, FR-4 (Fibreglass-Reinforced epoxy resin) is preferred. The substrate material used in PCB is insulating material. This material should be rugged and strong to give mechanical support to the PCB. The Solder Mask materials are used for the prevention of shortage in the interconnections. The conducting trace could get shorted if the Solder Mask is not provided. This Solder Mask is usually a polymer. These polymers help in preventing oxidation of the conducting material. The thin layer of the Solder Mask is deposited on the whole surface of the PC and it is done in a way that only the conducting traces are exposed. This is the most visible part of a PCB. It is usually Green, Blue or Black. Miscellaneous Materials: An extraordinary part of a PCB called Via or Via(s). These are small holes that are drilled into the base material. The Vias are usually made of copper and these are made of different depths if needed, sometimes they penetrate through the PCB. Other parts of PCB also include Connectors or Interconnectors are used to provide the external supply or connections, they let us do all the outer connections if needed. There are Male and Female Connectors, the first one is usually the pin headers and the latter is the sockets receptacles.
Step 1: Designing The Board CAD software is usually to make such designing. A 2D image is generated on the software of how the board will look and its components. Step 2: Substrate Material The FR-4 (fiberglass-reinforced epoxy resin) material is prepared. These are turned into sheets and then these sheets are trimmed into the required shape and size. Step 3: Depositing Copper Foil Copper foil of the required shape and thickness is used as conducting material and traces of it are deposited on the substrate. This is achieved by applying high heat and pressure. Step 4: Photoresist Process and Etching Here firstly a uniform thin layer of Photosensitive material is applied onto the copper foil. Then the whole board is exposed to UV radiation where the photosensitive exposed becomes sturdy and hard. The area where the material was not applied becomes soft and is removed later. After this, the board is dipped into a chemical bath where the unprotected areas get dissolved and the etching is achieved. After this, the remaining photo-sensitive material is removed by another chemical washed. Step 5: Applying Solder Mask and Drilling of holes Here, the green Solder mask is applied and the holes are drilled into the board. The holes are usually drilled by a CNC driller to avoid damage. Step 6: Applying Silkscreen The Silkscreen is usually a layer of ink used to notify the component and voltage details in the circuit. This is the final step and now we have a ready-to-be-used PCB.
PCB Assembly and Testing
Testing and assembly are the most important steps. Assembly is usually achieved by mounting the components onto the board in the right locations and checking if they fit into desired places with high precision. The Testing comes after Assembly, where circuit continuity is majorly checked. During testing, strict visual inspection and functionality check is done. The PCBs have to run to a certain standard to get their sale certification.
Advancement in PCB
There could be major advancements that can be seen in PCB Manufacturing. Recently better etching techniques are implemented in PCB to operate at higher frequencies, better speed, and reliable continuity. The usage of 3D printing made the manufacturing process time efficient. The automated robotic assembly line has also reduced manufacturing costs and defects.
If you are curious about “how are PCB boards made?” The process typically involves several steps. PCB is an essential element for electrical engineering and manufacturing electronics. It helps in giving identity to every process involved so that the operating system can easily determine between operations. It not only does this but also gives mechanical support and provides electrical connections to a circuit board’s electrical components. And hence is a very essential thing in electrical engineering.
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