PCB Technical - HDI circuit board commonly used laminated structure

1. A simple one-time build-up printed circuit board(6 layers of PCB boards are stacked at a time, and the laminated structure is (1+4+1)). This type of board is the simplest, that is, the inner multi-layer circuit board has no buried holes. The lamination is completed. Although it is a one-time laminated board, its manufacturing is very similar to a conventional multi-layer circuit board once laminated, except that the subsequent process is different from the multi-layer circuit board in that multiple processes such as laser drilling of blind holes are required. Since this laminated structure has no buried holes, in the production, the second and third layers can be used as a core board, the fourth and fifth layers can be used as another core board, and the outer layer is added with a dielectric layer and copper. The foil, which is laminated with a dielectric layer in the middle, is very simple, and the cost is lower than that of a conventional primary laminated board.

2. Conventional one-layer HDI circuit board (one-time HDI circuit board 6-layer PCB board, stacked structure is (1+4+1)) The structure of this type of board is (1+N+1), (N≥2, N even number), this structure is the mainstream design of the primary laminated board in the current industry. The inner multi-layer board has buried holes and needs to be pressed twice. This type of primary build-up board, in addition to the blind hole circuit board, also has buried vias. If the designer can convert this type of HDI circuit board into the first type of simple primary build-up board above, It is good for both supply and demand. We have many customers after our suggestion, it is preferable to change the laminated structure of the second type of conventional primary laminate to a simple primary laminate similar to the first type.

3. Conventional two-layer HDI circuit board (two-layer HDI 8-layer board, stacked structure is (1++1+4+1+1)). The structure of this type of board is (1+1) +N+1+1), (N≥2, N even number). This structure is the mainstream design of secondary laminate in the industry. The inner multi-layer board has buried holes and requires three presses to complete. The main reason is that there is no stacked hole design, and the production difficulty is normal. If the buried hole optimization of the (3-6) layer is changed to the buried hole of the (2-7) layer as described above, one press fit can be reduced and optimized Process and achieve the effect of reducing costs. This type is like the example below.

4. Another conventional two-layer HDI printed board (two-layer HDI 8-layer board, the stacked structure is (1+1+4+1+1)). The structure of this type of board (1 +1+N+1+1), (N≥2, N even number), although it is a secondary laminate structure, but because the position of the buried hole is not between (3-6) layers, but in (2 -7) Between layers, this design can also reduce the pressing time by one time, so that the second-layer HDI board requires three pressing processes, which is optimized to a two-time pressing process. And this kind of board has another difficulty to make. There are (1-3) layers of blind holes, which are divided into (1-2) layers and (2-3) layers of blind holes. -3) The inner blind holes of the layer are made by filling holes, that is, the inner blind holes of the secondary build-up layer are made by a filling process. Usually, the cost of HDI with a filling process is higher than the cost of not making a filling process. It is high and the difficulty is obvious. Therefore, in the design process of conventional secondary laminates, it is recommended not to use stacked hole design as much as possible. Try to convert (1-3) blind holes into staggered (1-2) blind holes and (2-3) Buried (blind) holes. Some experienced designers can adopt this kind of simple refuge design or optimization to reduce the manufacturing cost of their products.

5. Another unconventional two-layer HDI circuit board(two-layer HDI 6-layer PCB board, the stacked structure is (1+1+2+1+1)). The structure of this type of board ( 1+1+N+1+1), (N≥2, N even number), although it is a secondary laminate structure, there are also blind holes across layers, and the depth capability of the blind holes is significantly increased, (1- 3) The depth of the blind holes of the layer is double that of the conventional (1-2) layer. Customers of this design have their own unique requirements, and it is not allowed to make the (1-3) cross-layer blind holes into stacked holes. Type blind holes (1-2) (2-3) blind holes, this kind of cross-layer blind holes are not only difficult to drill by laser, but also the subsequent copper immersion (PTH) and electroplating is also one of the difficulties. Generally, PCB manufacturers without a certain level of technology are difficult to produce such boards, and the production difficulty is obviously much higher than that of conventional secondary laminates. This design is not recommended unless there are special requirements.

6. The HDI of the secondary build-up layer with blind hole stacked hole design, and the blind hole is stacked above the buried hole (2-7) layer. (Secondary build-up HDI 8-layer PCB board, stacked structure is (1+1+4+1+1)) The structure of this type of board is (1+1+N+1+1), (N≥2, N even number), this structure is currently part of the industry's secondary laminated panels have such a design, the inner multi-layer board has buried holes, and needs to be pressed twice. The main feature is the stacked hole design, instead of the cross-layer blind hole design in point 5 above. The main feature of this design is that the blind hole needs to be stacked above the buried hole (2-7), which increases the difficulty of production. The buried hole design is in (2-7). -7) Layer, can reduce one lamination, optimize the process and achieve the effect of reducing cost.

7. Cross-layer blind hole design of the secondary laminated HDI (secondary laminated HDI 8-layer board, the laminated structure is (1+1+4+1+1)). The structure of this type of board is (1+ 1+N+1+1), (N≥2, N even number). This structure is a secondary laminated board that is difficult to produce in the industry. With this design, the inner multilayer board has buried holes in the (3-6) layer, need three times of pressing to complete. Mainly there is a cross-layer blind via design, which is difficult to produce. HDI PCB manufacturers without certain technical capabilities are difficult to produce such secondary build-up boards. If this cross-layer blind via (1-3) layers, optimize the split For (1-2) and (2-3) blind holes, this method of splitting the blind holes is not the method of splitting the holes at points 4 and 6 mentioned above, but staggering the blind holes The split method will greatly reduce the production cost and optimize the production process.