When trying to understand how a printed circuit board works and its application, it’s essential to know the manufacturing process. Learning about the manufacturing process of PCBs can help you gain a more insightful understanding of the circuit board’s functioning. The manufacturing process for printed circuit boards introduces you to some of the most fundamental concepts of the PCB design.
Basic Board Structure
The PCB consists of multiple layers, and these layers also impact the manufacturing process. The critical layers of the printed circuit board include the copper layers. These are where you will find the traces. The traces are the wires within the circuit that connect the different components.
In a two-layered circuit board, you will have a top copper layer and a bottom copper layer. Between the two layers, you will find a dielectric material that is made of fiberglass. This fiberglass material is also called the Substrate, and engineers often refer to it as FR4.
In addition to that, most boards also contain a layer that sits on top of the copper, as well as on the bottom of it. This layer is called Soldermask, and it is a critical aspect of the PCB manufacturing process.
Soldermask
Soldermask is a layer of insulation that sits on top of the copper so that the components on the board are not in contact with each other. Very often, you can also find a layer of silkscreen on top of the printed circuit board. This silkscreen is text that allows you to identify the components inside a PCB.
The solder mask is the green layer of material that you find on PCBs. Whenever you have exposed copper on the PCB, you can apply a solder mask to it. The manufacturing process also involves making holes inside printed circuit boards, called through-holes.
These holes are plated through the board, with copper all the way through. These are the sorts of things that manufacturers will typically solder through. There are other types of holes, and engineers will call them Via.
Vias connect a wire on one layer to another layer. If you look at a board carefully, you will have lighter green areas and darker green areas. Where you have lighter green areas, you will find copper sitting on top of the FR4 Substrate.
Silkscreen
Copper on a printed circuit board is effectively on a large plane and traces. The silkscreen sits on top of the highest layer, which gives the reflection of the lighter colors on the board. Darker areas on the copper are simply solder mask and Substrate.
Manufacturing a Multilayered Board
In a multilayered board, what you have is a sandwich of individual boards. In other words, creating a multilayered board will require you to stack one board on top of another. A motherboard inside a computer can have about 16 layers which are very complex.
The Significance of the Process
The PCB process is incredibly complex. It encompasses multiple steps, and there are incredibly large boards with multiple different designs that are flowing through the factory. In today’s world, highly automated and large-scale machines make it possible to produce high volumes of Printed Circuit Board in a single day. This simple phenomenon has expanded the growth of technological innovations around the world, giving way to the acceleration of mechanical and electronic progress.
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