With the progress of electronic technology, the complexity of PCB (placa de circuito impreso), el ámbito de aplicación tiene un rápido desarrollo. Designers engaged in HF PCB must have relevant basic theoretical knowledge and rich experience in THE manufacture of HF PCB. In other words, both schematic drawing and PCB design should be considered from the high-frequency working environment, so as to design a more ideal PCB.

This paper, a PCB wiring, welding plate and apply the design method of copper, first of all, on the base of the PCB wiring, wiring, the power cord and the ground wiring requirements in the form of the paper introduces the design of the PCB wiring, second from the bonding pad and aperture, PCB pad size and shape of design in the design of the standard, the requirements of PCB manufacturing process pads are introduced the design of the PCB solder, Finally, from the PCB copper coating skills and Settings introduced the PCB copper coating design, specific follow xiaobian to understand.

Explicación detallada del método de diseño del cableado de PCB, placa de soldadura y revestimiento de cobre

PCB wiring design

El cableado es el requisito general del diseño de PCB de alta frecuencia basado en un diseño razonable. Cabling includes automatic cabling and manual cabling. Usually, no matter how many key signal lines there are, manual wiring should be carried out for these signal lines first. After wiring is completed, the wiring of these signal lines should be carefully checked and fixed after passing the check, and then other cables should be automatically wired. That is, the combination of manual and automatic wiring is used to complete PCB wiring.

The following aspects should be paid special attention to during the wiring of hf PCB.

1. La dirección del cableado

The wiring of the circuit is best to adopt a full straight line according to the direction of the signal, and 45° broken line or arc curve can be used to complete the turning point, so as to reduce the external emission and mutual coupling of high-frequency signals. El cableado de los cables de señal de alta frecuencia debe ser lo más corto posible. De acuerdo con la frecuencia de trabajo del circuito, la longitud de la línea de señal debe seleccionarse razonablemente para reducir los parámetros de distribución y reducir la pérdida de señal. When making double panels, it is best to route the two adjacent layers vertically, diagonally or bent to intersect each other. Avoid being parallel to each other, which reduces mutual interference and parasitic coupling.

High frequency signal lines and low frequency signal lines should be separated as far as possible, and shielding measures should be taken when necessary to prevent mutual interference. Para que la entrada de señal se reciba relativamente débil, fácil de ser interferida por señales externas, puede usar el cable de tierra para hacer un blindaje para rodearlo o hacer un buen trabajo en el blindaje del conector de alta frecuencia. Parallel wiring should be avoided on the same level, otherwise distributed parameters will be introduced, which will affect the circuit. If unavoidable, a grounded copper foil can be introduced between the two parallel lines to form an isolation line.

In the digital circuit, for differential signal lines, should be in pairs, as far as possible to make them parallel, close to some, and the length is not much different.

2. The form of wiring

In PCB wiring, the minimum width of the wiring is determined by the adhesion strength between the wire and the insulator substrate and the strength of the current flowing through the wire. When the thickness of copper foil is 0.05mm and the width is 1mm-1.5mm, 2A current can be passed. La temperatura no debe ser superior a 3 ℃. Excepto por algunos cables especiales, el ancho de otros cables en la misma capa debe ser lo más consistente posible. En el circuito de alta frecuencia, el espaciado del cableado afectará el tamaño de la capacitancia e inductancia distribuidas y, por lo tanto, afectará la pérdida de señal, la estabilidad del circuito y la interferencia de la señal. In high speed switching circuit, wire spacing will affect signal transmission time and waveform quality. Therefore, the minimum spacing of the wiring should be greater than or equal to 0.5 mm. It is best to use wide lines for PCB wiring whenever possible.

There should be a certain distance between the printed wire and the edge of the PCB (no less than the thickness of the plate), which is not only easy to install and machining, but also improve the insulation performance.

When wiring can only be connected around a large circle of the line, we should use the flying line, that is, directly connected with short line to reduce the interference brought by long-distance wiring.

The circuit containing magnetic sensitive elements is sensitive to the surrounding magnetic field, while the bend of wiring of high-frequency circuit is easy to radiate electromagnetic wave. If magnetic sensitive elements are placed in PCB, it should ensure that there is a certain distance between the corner of wiring and it.

No se permite ningún cruce en el mismo nivel de cableado. For the line that may cross, can use “drill” with “wound” method to solve, let a certain lead namely from other resistance, capacitance, audion etc. device lead foot gap place “drill” past, or from the end of a certain lead that may cross “wound” past. In special cases where the circuit is very complex, to simplify the design, it is also allowed to solve the crossover problem with wire bonding.

When the high frequency circuit operates at a high frequency, the impedance matching and antenna effect of wiring should also be considered.

Because the client finally changed the previous agreement and required the interface definition and placement as defined by them, they had to change the layout to the diagram on the right. In fact, the entire PCB is only 9cm x 6cm. It is difficult to change the overall layout of the board according to the requirements of customers, so the core part of the board was not changed in the end, but the peripheral components were modified appropriately, mainly the position of the two connectors and the definition of pins were modified.

But the new layout obviously caused some trouble in the line, the original smooth line became a little messy, the length of the line increased, but also had to use a lot of holes, the difficulty of the line increased a lot.

Explicación detallada del método de diseño del cableado de PCB, placa de soldadura y revestimiento de cobre

It is clear from this example that layout differences can have an impact on PCB design.

Explicación detallada del método de diseño del cableado de PCB, placa de soldadura y revestimiento de cobre

3. Wiring requirements for power cables and ground cables

Aumente el ancho del cable de alimentación de acuerdo con las diferentes corrientes de trabajo. La PCB de Hf debe adoptar un cable de tierra de área grande y un diseño en el borde de la PCB en la medida de lo posible, lo que puede reducir la interferencia de la señal externa al circuito; At the same time, the grounding wire of PCB can be in good contact with the shell, so that the grounding voltage of PCB is closer to the earth voltage. The grounding mode should be selected according to the actual situation. Different from the low-frequency circuit, the grounding cable of the high-frequency circuit should be nearby or multi-point grounding. The grounding cable should be short and thick to minimize the ground impedance, and the allowable current should be three times of the working current. The speaker grounding wire should be connected to the PCB power amplifier output level grounding point, do not arbitrarily grounding.

En el proceso de cableado todavía debe haber un bloqueo de cableado razonable a tiempo, para que no se repita el cableado muchas veces. To lock them, run the EditselectNet command to select Locked in the pre-wired properties.