What procedures are essential for 6 layer pcb manufacturing and fabrication?2020-04-24
What are 6 layer PCB manufacturing skills and steps?
Here are 6 layer pcb manufacturing skills and steps:
- Editing the schematic diagram
- Second, create a new PCB file, set the layer structure
- Third, the layout
- Fourth, the production of ground plane
- Fifth, the production of power plane
- Six, routing
- Seven, DRC inspection
Why are multi-layer boards generally even layers?
Do you want to improve your 6-layer pcb manufacturing skills?
Here are why multi-layer boards generally even layers? There are 4, 6, 8. . . 32, 64, etc. Just use HDI as an example:
The so-called layer refers to the circuit layer. According to different design methods. There can be 1 + N + 1, 2 + N + 2, 3 + N + 3 and so on. Double-sided board means that there are circuits on both sides of the substrate.
So the 4-layer board is based on the double-sided board. Add two layers of pp on both sides and lay two layers of lines separately. It becomes a 4-layer board (for 1 + 2 + 1 type). Same is the process with 6-layer pcb manufacturing.
How 6 layer pcb manufacturing take place?
In fact, 3, 5, 7 … there are quite a few shelves, but they don’t call it that.
In terms of production, in 6 layer pcb manufacturing, board is pressed from the core and then coated with copper foil. One core board is a four-layer board, two are six-layer boards. But there are still many three-layer boards. Furthermore, it is sufficient if one side of the core board is a light board.
But it is usually called a four-layer board. For example, the seven-layer board is actually one of the three core boards is a single-sided smooth board.
The so-called 126.96.36.199 …… The laminate is only called according to the process. There are actually many odd layers.
Four Layer pcb Can be manufactured in a PCB factory. The four-layer board is generally pressed with one copper foil on each side of a CORE, and the three-layer board is tested with one copper foil on one side. As far as the process is concerned, they must be pressed together.
The cost difference between 6 layer pcb manufacturing and 4 layer pcb
The difference in process cost between the 6 layer pcb manufacturing and 4 layer that there is one more copper foil and adhesive layer on the four-layer board.
The cost difference is not large. When the board factory quotes, generally the 3-4 layer is quoted as a grade, and the quote is an even number.
For example, if you design a 5-layer board, the other party will quote according to the price of the 6-layer board. Furthermore, that is to say, the price of your 3-layer design is the same as the price of your 4-layer design.
In the PCB process:
- the four-layer board is better controlled than the three-layer board.
- Mainly in terms of symmetry, the warpage of the four-layer board can be controlled below 0.7%.
- But the three-layer board is large.
At this time, the warpage will exceed this standard. it will affect the reliability of the SMT patch and the entire product. So the average 6 layer pcb manufacturing designer does not design odd-layer boards. Even if the odd-layer layers realize the function. Moreover, they will be designed as false even-numbered layers. That is to design 5 layers into 6 layers and 7 layers into 8 layers.
6 layer PCB design skills and steps detailed descriptions
Here are 6-layer pcb manufacturing and design skills and steps detailed descriptions:
- Editing the schematic diagram
The 6-layer board can have two layers of ground in the PCB board. So the analog and digital grounds can be separated. Therefore, for the problem of uniform or separate, involving the minimum return path of the signal in electromagnetic interference. Similarly, after drawing the schematic diagram, don’t forget to check the error. And check the package manager to check the component package.
2. create a new PCB file, set the layer structure 6 layer pcb manufacturing
After creating a new one, you can import the schematic netlist to a PCB file for 6 layer pcb manufacturing. The next thing to do is to set the layer structure (layer stack manager), add layer is to add an intermediate signal layer.
And add plane is to add internal power and internal ground layers. The middle signal layer is the same as the top layer and the bottom layer.
- The signal lines are placed.
- The signal lines represent copper, and
- the places without signal lines are insulated.
- The internal power supply and the ground layer generate a copper mold.
- The line used when dividing the internal electrical layer represents the eroded copper.
The dark red represents the eroded copper. And the other regions represent the copper mold. Another point in 6-layer pcb manufacturing is that the power layer and the main ground layer should be tightly coupled. Preferably at a distance of 5 mi (prepreg).
The layout procedure in 6 layer pcb manufacturing
The main principle of layout in 6 layer pcb manufacturing is to partition well. Moreover, the partition of analog devices and digital devices. Which can reduce interference. Because the interference generated by digital signals is large and the anti-interference is also strong.
While the interference generated by analog signals is relatively small. But it is susceptible Digital signal interference.
Another point is to pay attention to the layout of components with different operating voltages. And devices with large voltage differences should be far apart. For the decoupling capacitors of some chips, the closer to the pins, the better.
“The other thing to note is that the pins of the same network are close, pay attention to the beautiful layout.”
- there are 3 signal layers and 3 power layers
- of which GND is two and five layers
- and the middle layers of 3 and 4 are Power and middle signal layers.
If there are fewer traces in the middle signal layer in 6 layer pcb manufacturing, it is appropriate to apply copper on the middle signal layer.
Each signal layer is adjacent to the inner electrical layer. Moreover, there is no directly adjacent signal layer, to avoid crosstalk of signals between layers.
The high-speed signal line can be arranged on the signal layer 5. So that it can be effectively shielded by the ground layer and the power layer.
4. the production of ground plane 6 layer pcb
6 layer pcb manufacturing has two layers of ground:
Generally, both are separated and located on the second and fourth layers respectively. So the operation of the ground network is relatively easy.
The ground network pins of the top and ground components are led out with wires and connected to the corresponding network through the via hole. Use as few pads as possible during the connection process. Because the pads will bring capacitance effects and increase interference.
5. the production of power plane in 6 layer printed circuit boards
Since the multilayer board will not have only one working voltage value, the power layer generally needs to be divided.
The specific steps for segmentation during 6-layer pcb manufacturing are as follows:
- Highlight a voltage network
- switch to the inner power layer
- use line to draw a closed graph
- the closed area is the network of the voltage;
- Lead out the pins of the top layer and ground layer with wires, and
- connect to the inner power layer through the pad;
- Draw the next power network
line is the dividing line of the two networks, which is the eroded part.
During 6 layer pcb manufacturing, a pcb manufacturer should pay attention to the following too:
- the area of large voltage difference should be wider
- the unused copper mold can be placed on the plane to corrode its area during manufacturing
- do not place the pad on the dividing line to affect its internal Electrical layer contact.
6. 6 layer pcb manufacturing routing
Make the power layer and ground layer well. And then you can route the signal lines. When routing during 6 layer pcb manufacturing, the important high-speed signal line is best to go to the inner signal layer.
Another principle is that the signal should go on its own ground layer.
For example, if most of the top layer is analog signals, the second layer is best set to AGND. Since the layer structure has been set up in the front, this point needs to be considered when routing signal lines.
In addition, when wiring, the component layout needs to be adjusted appropriately to facilitate wiring. The wiring between the top layer and the ground layer is no different from the two-layer board.
For the inner signal layer in 6 layer pcb manufacturing, the routing method is wire-pad-inner electric layer. Priority placement and routing of DDR FPGA FPC cables, etc.
Use 5mil (0.127mm) width of the signal line traces. Using the power supply line (16mil) line width of 0.4mm, the theoretical line may 10mil over- current to 1A.
Following are 8 instructions for 6 layer pcb manufacturers
- 1-For important signals, perform differential wiring, set wiring groups, and perform equal-length processing.
- 2, FPGA or the like for a multi-pin pin function independent, may be arranged into groups, to facilitate the swap PI n-operation.
- 3-For BGA packaged devices, first arrange the cables. And then lead out the outermost two layers of pins, and then arrange the cables. For the inner layer, it is difficult to lead the cables. It can be appropriately led to other layers.
- 4-For the DDR data line, try to ensure that the data line is a cluster, and the clock line is isolated from the data line.
- Moreover, the connection between the two chips can go through two vias at most.
- You can select the schematic diagram and then link to the PCB. In this way, you can effectively select specific components.
- For those that can no longer lead by the pin, the lead can be led to the outside and lead farther away in 6 layer pcb manufacturing.
- For the GND and Power in the BGA, the wire should be led out during wiring to avoid the wiring being too dense and unconnected GND and Power.
When the components are not dense and there is a certain empty area. Therefore, it is best to lay the ground. And the ground is also divided into AGND and DGND. So the local grounding operation should be carried out separately. For the tear drop, generally need to be carried out.
7. 6 layer pcb manufacturing DRC inspection
This step is very important for 6-layer pcb manufacturing. After the drawing of the board is completed, it must be carried out to check. Whether there are any places that have not been found in violation of the rules.