Take apart the inside of the phone and you’ll find that in addition to the display screen and trackpad, the core of the phone is a circuit board filled with various electronic components.
So the question is, how is this electronic circuit board made?
Today we will talk about the whole process of electronic circuit boards from scratch.
The first thing to understand is that the electronic Circuit Board is also called the motherboard, usually known as the PCB (Printed Circuit Board, printed circuit board). The PCB board integrates various components, such as resistors, capacitors, inductors, diodes, etc., and of course includes IC chips with different functions. It is these components that work together to form the electronic product motherboard that we use with a variety of functions.
However, electronic motherboards do not appear in a vacuum, and its production is a gradual process.
The first step in this process is the design of the electronic motherboard, and the starting point of the design is the drawing of the schematic diagram.
The schematic diagram is a diagram that shows the connection between the components on the circuit board. Any diagram that can reflect the working principle of a circuit can be called a schematic diagram.
(Figure: schematic diagram of a tachometer)
In the actual production, the circuit principle of each module of the electronic motherboard is separate. On the one hand, the drawing area is limited, and on the other hand, the modules are connected through network signals. As long as the network signal is labeled correctly, the schematic will not be confused.
Through the schematic, you can clearly understand the working principle of each module in the circuit board, as well as the flow of signals and power supplies, so as to glance at the core design of the circuit board
When designing the schematic diagram, it is also necessary to consider the selection of components, such as package format, withstand voltage value and EMC (electromagnetic compatibility). Therefore, the selection of components in schematic design is a very time-consuming and laborious work. After the selection is completed, a BOM (Bill of Materials) is usually generated.
After the schematic is completed, the next step is to convert the components in the diagram into an actual PCB board.
So, how does this process work?
This requires that each component in the schematic diagram be transformed into a physical shape in reality, and gradually realize the transition from design to physical object.
This is where the concept of encapsulation needs to be introduced. The package is to connect the circuit pin on the silicon chip to the external connector by wire for connection with other devices. Simply put, packaging determines the physical existence of a component. For example, a 10Ω resistor can be packaged as a pin plug-in type or as a pin free patch type. The choice of this packaging form directly affects the layout and installation of components.
The package is reflected in the shape and pin arrangement on the component, and on the PCB, it is expressed in the pitch, area and number of contact points. In short, PCB packaging is the physical mapping of components on the circuit board.
Next is the drawing of the PCB board. First of all, you need to draw the mechanical frame and determine the approximate shape and size of the circuit board. The components are then placed inside the box, and usually modules with the same function are arranged in adjacent areas.
If there is a ready-made component library, you can directly select the component corresponding to the schematic, and the PCB board will automatically generate the package position of the component.
At the beginning of the design, it is also necessary to consider the number of PCB layers. For simple circuits, usually only one or two layers are needed, that is, the top layer and the bottom layer. If the circuit is more complex and has more functions, you need to increase the number of PCB layers, such as the power layer, ground layer and solder resistance layer.
When the PCB layout of all components is completed, it can be routed. This step can be done automatically or manually. Wiring is to connect the wires in the circuit according to the schematic diagram, of course, in the actual design, the position of the wire needs to be adjusted according to the specific situation.
After the wiring is complete, you can see the preview of the PCB. If the software supports it, you can also view 3D renderings to show the final stereoscopic molding effect of the circuit board. This not only helps to check the rationality of the design, but also preview the actual appearance of the board in advance.
After completing all the above steps, the final step is to convert the designed PCB diagram into a physical circuit board.
This process requires a special PCB equipment or PCB factory to proofing according to your design drawing, and the proofing effect is shown in the following figure.
Next, the corresponding electronic components (such as resistors, capacitors, ics, etc.) are welded to the PCB board using solder paste or solder, and the entire electronic circuit board is finally completed.
