Printed Circuit Board Laminated Design Principles and Methods

Under normal circumstances, when designing ordinary single and double panels, there is no need to consider the lamination problem of PCB, and the copper clad plate with copper thickness and plate thickness meeting the design requirements are usually directly selected for direct processing. However, when designing a PCB with more than 4 layers, the laminated design directly affects the performance and price of the PCB.

The multi-layer PCB is made of copper clad Core board (Core), semi-cured sheet (prepreg, referred to as PP) and copper foil, which are combined according to the laminated design and are made by pressing.

Before the PCB design begins, Layout engineers will determine the number of layers of the PCB according to the size of the board, the size of the circuit and the requirements of electromagnetic compatibility (EMC), and then determine the layout of the components, and finally confirm the division of the signal layer, the power layer and the formation.

PCB laminated design principles

PCB lamination needs to be considered from many aspects such as the number of layers, signal type, board thickness, material selection, copper thickness, impedance control, EMI/EMC shielding, thermal management, cost and testability.

Meet the signal integrity requirements of high-speed signal wiring

For critical Signal lines, it is necessary to build a laminated combination of GND/Signal/GND, strip lines of adjacent signal layers, and cross vertical wiring to minimize crosstalk coupling. From the point of view of signal integrity, Stripline lines are used for critical high-speed signals, and Microstrip lines can be used for non-critical high-speed signals.

If not necessary, it is not recommended to use Broadside-Coupled Stripline, PCB processing exposure and etching offset will cause overlap dislocation, processing is difficult and difficult to ensure impedance consistency.

There are a variety of PCB lamination design methods, the following are some common lamination design methods:

For the signal layer, usually each signal layer is directly adjacent to the internal electrical layer, and has effective isolation from other signal layers to reduce crosstalk. In the design process, multiple reference ground planes can be considered to enhance the electromagnetic absorption capacity.

In a multi-layer board design, such as a 10-layer board, there may be different lamination schemes depending on the needs of the power layer. For example, in the case of a single power layer, one solution is S G S S G P S S G S s g s; For the case where two power layers are required, the scheme of S G S S G P S S P S can be considered.

In a specific stacking setup, crosstalk can be controlled by increasing the spacing between certain layers, such as increasing the spacing between S1 to S2 and S3 to S4.

Considering electromagnetic absorption capacity and power supply impedance, some lamination methods may have better performance. For example, PCB boards that use multilayer ground reference planes usually have better electromagnetic absorption capacity.

The laminated design also needs to consider signal integrity, PCB layers that avoid discontinuities and loops, capacitor decoupling and flux elimination, and avoiding unwanted impedances and loops.

The impact of laminated design on the circuit is mainly reflected in the following aspects:

First, the laminated design can effectively improve power quality and reduce crosstalk and electromagnetic interference (EMI). Through a reasonable stacking layout, such as the signal layer and the power layer or the ground adjacent, can optimize the electromagnetic field distribution, reduce the coupling interference between the layers, improve the overall performance of the circuit.

Secondly, laminated design helps to save costs. In a limited space, by increasing the number of circuit layers, the integration of the circuit can be improved without increasing the PCB area and more functions can be achieved. This helps to reduce the size of electronic devices and meet the trend of miniaturization of modern electronic devices.

Moreover, the layer-on design can improve the anti-interference ability of the circuit. By introducing insulation layer in the layer, the interference and crosstalk between circuits can be reduced, and the stability and reliability of circuits can be improved. This is especially important for high-speed, high-frequency circuits to ensure the accuracy and integrity of signal transmission.

In addition, the layered design can also reduce the transmission delay of the circuit. Due to the short distance transmission between the circuit layers, the transmission time of the signal can be greatly reduced, thus improving the working efficiency of the circuit. This is important for applications that require high-speed data transmission.

It is important to note that laminated design also needs to weigh various factors. For example, while increasing the number of circuit layers can improve integration and performance, it also increases manufacturing costs. At the same time, the complexity of the laminated design will also increase with the increase of the number of layers, which may increase the difficulty of design and manufacturing. Therefore, in the lamination design, it is necessary to consider the performance, cost, manufacturing difficulty and other factors to find the most suitable lamination scheme.