Product Details

What is 4 layer PCB?

Four-layer circuit board is a kind of Printed Circuit Board . It is made of four layers of glass fibre, which can reduce the cost of PCB.

Compared with Double Sided PCB, multi-layer PCB have many advantages. They can be designed more compactly. They can greatly improve noise resistance and make layout easier.

There are also great differences between the 2-layer and 4-layer PCB.

Stack up forms for the 4-layer PCB

The standard 4-layer PCB stack is shown below, and GND and VCC can be switched according to the layer with more signals.

If you don't want to connect all the ground pins through the hole, there will be different stacks and wide power routing on the signal plane.

What's the difference between 2 layer and 4 layer PCBs?

1. The four-layer board has a GND and POWER layer in the middle of the TOP layer and the BOTTOM layer

2.Features of four-layer board: 1. Reference plane, impedance calculation can be carried out, 2. The return path is shorter, 3. The number of layers is more, the design is simpler, 4. The cost is higher

3. Based on the wiring density (after the layout, look at the densest place of the flying lines, at least two layers of wiring are required for the places where the flying lines cross), cost (design a multilayer board if you don’t care about the cost), and signal quality to consider whether to judge whether Choose a four-layer board

4. It is judged how many layers to use after the layout. After the layout, look at the density of the signal and the place with the most flying lines

Why choose to design four layer PCB?

1. When there is a BGA package, the outer two rows can be directly pulled out to go to the surface layer, the third and fourth layers can be punched to go to the bottom layer, and the fifth and sixth rows can be drilled to go to the bottom layer. However, the power and ground wires inside You can't get out, you need to add layers, add two more layers (usually the number of layers is even)

2. The power cable blocks the signal cable

3. Some line density is not high, two layers can be done, but based on signal considerations, the quality of the signal is given priority, you can choose to use a four-layer board

4 layer stack up:

1. The signal layer is on the top and bottom layers, and the power layer and ground layer are in the middle (two types)

2. The signal layer is in the middle, the power layer is on the top layer, and the ground layer is on the bottom layer

A: The ground is as complete as possible. For example, comparing the first stack and the third stack, the first component will divide the ground, and the third one is complete, which is better

B: Comparing the first and the third, the third is better, the signal lines are not adjacent

C: At this point, there is no difference in the stacking method above

D: At this point, there is no difference in the stacking method above

Through these four, the third or second stacking scheme is preferred. The third and second stacking method is different in that the ground is first walked on the layer close to the ground. The most common are the second and third. Two types of stacking methods

What is the positive film layer and what is the negative film layer: the wire drawn by the positive film layer is copper, and the line drawn by the negative film layer is not copper. In most cases, the negative film layer is used, and the complexity will be reduced a lot

How to add a layer stack: Add in the layer stack manager (D+K (layer stack manager)), select the TOP layer, and then add internal layer (add negative layer), after adding you can change the layer name (for example, GND02 \POWER03)

There is basically no need to change the type of layer (whether it is a negative layer or a positive layer) and materials, the thickness of the layer can be set, and a stack calculation is required.

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