The stacked structure is an important factor affecting the EMC performance of PCB boards and an important means of suppressing electromagnetic interference. With the continuous emergence of high-speed circuits, the complexity of PCB boards is also increasing. In order to avoid electrical interference, the signal layer and power layer must be separated, which involves HDI multi-layer board stacking design. So, what are the commonly used stacking structures for HDI multilayer boards?

1. Simple one-time laminated printed circuit board

Six layers are stacked at once, with a stacking structure of (1+4+1). This type of panel is the simplest, that is, the inner multi-layer board has no buried holes and can be completed in one press. Unlike multi-layer boards, multiple processes such as laser drilling of blind holes are required in the future.

2. Conventional one-time layered HDI printed circuit board

One layer HDI 6-layer board is stacked to form a structure of (1+4+1). The structure of this type of board is (1+N+1), (N ≥ 2, N even), which is currently the mainstream design of primary laminated boards in the industry. The inner multi-layer board has buried holes and requires secondary pressing to complete.

3. Conventional secondary layer HDI printed board

The secondary layer HDI 8-layer board is stacked into a structure of (1++1+4+1+1). The structure of this type of panel is (1+1+N+1+1), (N ≥ 2, N even number), which is currently the mainstream design of secondary layering in the industry. The inner multi-layer panel has buried holes and requires three pressing cycles to complete.

4. The second type of conventional secondary layer HDI printed board

The secondary layer HDI 8-layer board is stacked into a structure of (1+1+4+1+1). The structure of this type of board (1+1+N+1+1), (N ≥ 2, N even numbers), although it is a secondary laminated board structure, the buried holes are not located between layers (3-6), but between layers (2-7). This design can reduce the number of lamination by one, making the secondary laminated HDI board require three lamination processes, optimizing it to a two-step lamination process.

5. HDI of secondary layer with blind hole stacking design

Blind holes are stacked on top of the buried holes (2-7) layer, and a secondary layer of HDI 8-layer board is stacked to form a structure of (1+1+4+1+1). The structure of this type of panel is (1+1+N+1+1), (N ≥ 2, even N), and the inner multi-layer panel has buried holes that require secondary pressing to complete.

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

The secondary layer HDI 8-layer board is stacked into a structure of (1+1+4+1+1). The structure of this type of panel is (1+1+N+1+1), (N ≥ 2, N even). This structure is a secondary layer panel that is currently difficult to produce in the industry. The inner multi-layer panel has buried holes in layers (3-6) and requires three pressing cycles to complete.

7. Optimization of HDI panels with other stacked structures

Triple layered printed boards or PCB boards with more than three layers can also be optimized. A complete HDI board with three layers requires four presses.