Select Components According to PCB Package
The PCB encapsulation actually displays the various parameters (such as size, length and width, size of pad, etc.) of components, chips, etc. in a graphical manner. So that they can be called when drawing the PCB diagram. Therefore, before the PCB design, components selecting becomes the most important thing. Otherwise, you will always meet different problems during the design. This will cause the PCB boards which you to spend a lot of time designing do not work in practice. Today, I will introduce some points to pay attention to when choosing PCB components.
The main thing here is analyzing how to selecting components from PCB design and encapsulation. The encapsulation of components contains a lot of information. It Contains the dimensions of the component. Especially the relative position relationship of pins, and pad types for components. In addition, we have to pay special attention to the overall dimensions of the components when selecting components according to component encapsulation.
Pin position relationship: It mainly means that we need to correspond the actual component pins with the encapsulation size of PCB components.
Although different components have the same function, the encapsulation of components is likely to be different. It is necessary to ensure that the PCB pad size and position are correct, in order to ensure that the components can be welded correctly.
First, the types of pads. There are two types, one is Plated Through Hole (PTH), and the other is Surface Mounted Type (SMT). The factors that need to to considered include device cost, availability, device area, density and power consumption, etc. From the aspect of product design, SMT devices are usually cheaper than PTH devices, and have higher availability. For our design in general, choosing SMT, is not only facilitates manual welding, but also beneficial to better connection of pads and signals in the process of error checking and debugging.
Secondly, we should also pay attention to the positions of the pads. Because different pad positions represent different components positions.
If the positions of pads are not arranged properly, it is likely that the components in one area are too dense, while the components in another area are very sparse. Without doubt, the worse situation will be that cause the position of the pad is too close, so the component cannot be welded because the gap is too small.
Another situation is that we have to consider how to weld the pads. In the actual operation process, we usually arrange the pads in a particular direction, which is more convenient for welding.
Dimensions of components: In practical applications, some components (such as polar capacitors) may have Net Height limited, so we have to consider them in the component choosing process. At the beginning of the design, we can draw a basic outline shape of the circuit board, and then place some large or key location components (such as connectors) that you plan to use. In this way, we can directly and quickly see the virtual perspective view of the circuit board (without wiring), and figure out a relatively accurate relative positioning and component height of circuit boards and components.
This will help ensure that the components can be properly placed in the outer packaging (plastic products, chassis, frame, etc.) after PCB assembly. Quite rightly, we can also call the 3D preview mode from the Tools Menu to browse the entire circuit board.
For the selection of components, besides the design requirements, we should also choose the products from regular manufacturers. Only in this way can we ensure the realization of the target.