The stack structure is an important factor affecting the EMC performance of PCB, and also an important means to suppress electromagnetic interference. With the continuous emergence of high-speed circuits, the complexity of PCB boards is also getting higher and higher. In order to avoid the interference of electrical factors, the signal layer and power layer must be separated, so it involves the HDI multilayer board stack design. What are the common stack structures of HDI multilayer boards?

1. Simple once laminated printed board 

Six layers of boards are stacked at one time, and the stacking structure is (141). This type of plate is simple, that is, the inner multilayer plate has no embedded hole, and the pressing is completed in one time. Different from multilayer boards, there are multiple processes such as laser drilling blind holes.

2. Conventional once laminated HDI printed board 

The HDI 6 layers are stacked at one time, and the stacking structure is (141). The structure of this type of panel is (1 N 1), (N ≥ 2, N even number). This structure is the mainstream design of primary laminates in the industry at present. The inner multilayer plates have embedded holes, which require secondary pressing.

3. Conventional secondary build-up HDI printed board 

The secondary stacking HDI 8-layer board has a stacking structure of (11.411). The structure of this type of plate is (1 1 N 1 1), (N ≥ 2, N even number). This structure is the mainstream design of secondary lamination in the industry at present. The inner multilayer plates have embedded holes, which need three times of pressing.

4. The second kind of conventional secondary build-up HDI printed board 

The secondary stacking HDI 8-layer board has a stacking structure of (11.411). Although the structure of such plates (1 1 N 1 1), (N ≥ 2, N even number), is the structure of secondary laminates, since the location of the buried holes is not between (3-6) layers, but between (2-7) layers, this design can reduce the pressing once, so that the HDI plates of secondary laminates need three pressing processes, which are optimized into two pressing processes.

5. HDI of secondary stack for blind hole stack design 

The blind holes are stacked above the buried holes (2-7) layer, and the secondary HDI 8 layers are stacked in a (11411) structure. The structure of this type of plate is (1 1 N 1 1), (N ≥ 2, N even number), and there are embedded holes in the inner multilayer plate, which requires secondary pressing.

6. HDI of secondary layer of cross layer blind hole design 

The secondary stacking HDI 8-layer board has a stacking structure of (11.411). The structure of this type of plate is (1 1 N 1 1), (N ≥ 2, N even number). This structure is a secondary laminated plate that is difficult to make in the industry at present. There are embedded holes in the (3-6) layers of the inner multilayer plate, which requires three times of pressing.

7. Optimization of HDI boards with other laminated structures 

Third build up PCB or PCB with more than three build ups can also be optimized. A complete third build up HDI board requires four laminations.