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Marking specification of circuit board
No rules, no standards. This is almost a universal truth, and the PCB design industry is no exception.
Just imagine, if the PCB circuit board you design does not meet some of these specifications, it will either affect the process flow in the PCB manufacturing process, or affect the product quality and electrical performance of the board, and then affect the stability and service life of the equipment.
In view of this, today we once again invited a big man from Benqiang Circuit PCB Design Division to explain to us the next important design link in PCB design, the labeling of PCB circuit boards.
1. Components and soldering surfaces should have the number and version number of the PCB or PBA. The light board number is marked on the welding surface of the board, and the mounting solder number is marked on the component side. The mounting solder number is generally added by 1 after the light board number.
2. When labeling, the top layer (first layer) should be the component surface, and it should be a positive figure, while the welding surface is a reverse figure (horizontal mirror image), such as the character'b', the component surface is displayed as'b', and the welding surface is displayed as'd. '.
3. If the board is to be silk-screened, the silk-screened characters should have a height of 1.5~2.0mm and a line width of 0.2~0.254.
4. Identification of each layer of PCB
For multi-layer PCB boards, for the needs of production inspection (such as during lamination), the different base layers of the circuit board should be marked and named
1) Edge Layer Marking of multilayer boards
The edge layer identification is: on the edge of the board, put a 1.6mm long and 1.0mm wide copper on each layer. The edge layer marks of each layer are arranged in order from the top to the bottom, respectively, from left to right.
The order of marking on PCB edge layer
2) Layer identification and naming of multilayer boards
In order to meet the process requirements of PCB production and increase the readability of the identification of each level, the number of layers should be added to the multi-layer board as shown in the figure:
Layer identification and naming of multilayer boards
A. The numbering principle of each layer of the multilayer circuit board:
There are fixed numbers for the top and bottom layers: Top Layer is KK; Bottom Layer is KA. The number of the middle layer from the bottom to the top is: KA, KB, KC, KD ... KK (where KI is not used). It can represent up to 10 layers of boards, as shown below: (There are two ways to represent, the second is recommended)
1. For 2-layer boards:
Top Layer KK 1
Bottom KA 2
2. For 4-layer boards:
Top Layer KK 1
Middle 1 layer KC 2
Middle 2 layer KB 3
Bottom KA 4
3. For 6-layer PCB board:
Top Layer KK 1
Middle 1 layer KE 2
Middle 2 layer KD 3
Middle 3 layers KC 4
Middle 4 layer KB 5
Bottom KA 6
4. For 8-layer circuit board:
Top Layer KK 1
Middle 1 layer KG 2
Middle 2 layer KF 3
Middle 3 layers KE 4
Middle 4 layer KD 5
5 middle floors KC 6
Middle 6th floor KB 7
Bottom KA 8
5. For 10-layer PCB circuit board:
Top Layer KK 1
Middle 1 layer KJ 2
Middle 2 layer KH 3
Middle 3 layer KG 4
Middle 4 layers KF 5
Middle 5 layers KE 6
6 middle layer KD 7
7 middle floors KC 8
Middle 8 layers KB 9
Bottom KA 10
6. When the number of layers of the printed circuit board reaches 12 layers, change the letter K in the previous digit to L. For a 12-layer board, the following is shown, and the 12-layer board is followed by analogy.
Top Layer KK 1
Middle 1 layer LB 2
Middle 2 layer LA 3
Middle 3 floors KJ 4
Middle 4 layer KH 5
5 middle layer KG 6
6 middle floors KF 7
Middle 7th floor KE 8
Middle 8 layers KD 9
9th floor KC 10
The middle 10 layers KB 11
Bottom KA 12
B. Numbering principle of multi-layer board
The labeling principle is:
■ The labels of each layer should be placed on the respective layer, expressed by the text of the current layer (TEXT)
■ The label of the top layer is a positive character (positive character) when viewed from the top to the bottom; and the label of the bottom layer is a reverse character (anti-character) when viewed from the top to the bottom.
■ The other layers are counted from the top to the bottom, odd numbers are inverse characters, and even numbers are positive characters.
