Basic knowledge of PCB design

What is a part package and how is it different from a part ?

(1) Part packaging refers to the appearance and solder joint position indicated when the actual part is soldered to the circuit board.
(2) The part package is only the appearance of the part and the location of the solder joints. The pure part package is only the concept of space, so different parts can share the same part package; on the other hand, the same part can also have different packages, such as RES2 stands for resistance, and its package forms include AXAIL0.4, AXAIL0.3, AXAIL0.6, etc., so when taking soldered parts, you must not only know the name of the part but also the package of the part.
(3) The packaging of parts can be specified when designing the circuit diagram, or when introducing the network list. When designing the circuit diagram, it can be specified in the Footprint setting item in the part property dialog box, or the part package can also be specified when importing the network table.

What is the difference between wires, flying leads, and networks?
Conductors are also called copper film traces, referred to as conductors, which are used to connect various solder joints and are the most important part of printed circuit boards. The design of printed circuit boards is based on how to arrange the conductors.
Another kind of wire related to the wire is often called a flying lead or a pre-drawn wire. Flying wires are generated by the system according to the rules after the network table is introduced, and are used to guide wiring.
There is an essential difference between flying leads and wires. The flying lead is just a formal connection, which only formally shows the connection relationship between the various solder joints, and has no electrical connection meaning. The wire is arranged according to the connection relationship between the solder points indicated by the flying wire, and has the meaning of electrical connection.

Nets and wires are different, and solder joints are also included on the net, so when referring to nets, not only the wires but also the solder joints connected to the wires are included.

What is the difference between inner and middle layers?
 The middle layer and the inner layer are two easily confused concepts. The middle layer refers to the middle board layer used for wiring, and the wires are distributed in this layer; the inner layer refers to the power layer or ground layer, which is generally not wired. It is composed of a whole piece of copper film and is a negative correspondingly displayed.

What is an internal netlist and an external netlist, and what is the difference between them?
The network list can be divided into external network list and internal network list. The external netlist refers to the imported netlist, that is, the schematic netlist generated by Sch or other schematic design software; the internal netlist is the netlist used for wiring inside the PCB system after modification based on the imported external netlist. Strictly speaking, these two netlists are completely different concepts, but readers do not need to strictly distinguish them.

What does the Netlist Manager do?

First, introduce the netlist. The introduction process of this netlist is actually the process of loading the data of the schematic diagram design to the PCB of the printed circuit board design system. All changes in the data in the PCB design system can be done through the Netlist Macro. The system automatically generates the Netlist Macro by comparing and analyzing the netlist file and the internal data of the PCB system. Second, the network list manager can be used to directly edit the connection relationship between the various components of the circuit board in the PCB system to form a network list.

What is a class, and what are the benefits of introducing the concept of a class?

The so-called class refers to a collection of units with the same meaning. The class definition in PCB is open to users, and users can define the meaning and composition of classes by themselves. The introduction of classes in PCB has two main functions:
(1) Easy wiring In the process of circuit board wiring, some networks need special treatment, such as some important data lines, in order to avoid interference from other components on the circuit board, it is often necessary to increase these data lines and other components during wiring safety distance between them.
(2) Easy to manage circuit board components For a large circuit board, there are many component packages on it, and there are thousands of networks, which is very messy, and the circuit board can be easily managed by using classes. For example, to classify all input networks in the circuit board, when looking for an input network, you only need to search in this input network class; you can also classify all voltage limiting resistors in the circuit board, and when looking for a For voltage limiting resistors, just search in this voltage limiting resistor category.

How to add additional solder joints to the network?

You can add the solder joints to the circuit board first, then double-click the solder joints to open the solder joint attribute setting dialog box, select the appropriate network in the Net item in Advanced, and then complete the placement of the solder joints.

What is the use of inner division?

The divided inner layer can be used to connect some important lines, which can improve the anti-interference ability and protect important circuits.

What is the function of copper cladding, and what should be paid attention to?

The main function of copper coating is to improve the anti-interference ability of the circuit board. If the line is to be wrapped with wires or filled with teardrops, then the copper coating should be done at the end.

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