PCB News - HDI PCB board commonly used laminated structure

1. Simple one-time build-up printed PCB circuit board(one-time build-up 6-layer board, laminated structure is (1+4+1))

This type of board is the simplest, that is, the inner multi-layer board has no buried holes, and it can be laminated in one time. Although it is a laminated board, its manufacturing is very similar to the conventional multi-layer board once laminated, but the follow-up is different from the multi-layer board. It requires multiple processes such as laser drilling of blind holes. 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 printed board (one-time HDI 6-layer 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 industry at present. The inner multi-layer board has buried holes and requires secondary The pressing is complete. In addition to blind holes, this type of primary build-up board also has buried holes. If the designer can convert this type of HDI into the simple primary build-up board of the first type above, it will be a problem for both supply and demand. Is helpful. 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 printed circuit board (two-layer HDI 8-layer board, the 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 the secondary buildup in the industry. The inner multilayer board has buried holes. It takes 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 location of the buried hole is not in (3-6) Between layers, but between (2-7) layers, this design can also reduce the compression by one time, so that the second-layer HDI board requires three compression processes, which is optimized to a two-fold compression 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 filling holes. Generally, the cost of HDI with filling holes is higher than the cost without filling holes. 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 printed board (two-layer HDI 6-layer board, the stacked structure is (1+1+2+1+1))

The structure of this type of board is (1+1+N+1+1), (N≥2, N even number). Although it is a secondary laminate structure, there are also cross-layer blind holes and the depth of the blind holes. The capacity has been significantly increased. The depth of blind holes in the (1-3) layer is double that of the conventional (1-2) layer. Customers of this design have their own unique requirements and are not allowed to cross (1-3). Layer blind holes are made into stacked blind holes (1-2) (2-3) blind holes. In addition to the difficulty of laser drilling, this kind of cross-layer blind holes is also one of the difficulties in subsequent copper sinking (PTH) and electroplating. . 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 board, stacked structure is (1+1+4+1+1))

The structure of this type of panel is (1+1+N+1+1), (N≥2, N even number). This structure is currently part of the industry’s secondary laminated panels with such a design, inner multi-layer The 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. Secondary build-up HDI with cross-layer blind via design (second build-up HDI 8-layer board, stacked structure is (1+1+4+1+1))

The structure of this type of panel is (1+1+N+1+1), (N≥2, N even number). This structure is a two-layer laminated panel that is currently difficult to produce in the industry. Design, the inner multi-layer board has buried holes in the (3-6) layer, which requires 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.

8. Optimization of HDI panels with other laminated structures

Three-layer build-up printed boards or PCB boards with more than three build-ups can also be optimized according to the design concept provided above. For a complete three-layer HDI board, the entire production process requires 4 presses., If you can consider the design ideas similar to the above-mentioned primary or secondary laminated panels, the production process of primary pressing can be completely reduced, thereby increasing the yield of panels. Among our many customers, there is no shortage of such examples. The laminated structure designed at the beginning requires 4 times of pressing. After the optimization of the laminated structure design, the production of PCB only needs 3 times of pressing. The function that meets the needs of the three-layer laminated board.

The above is an introduction to the commonly used laminated structure of HDI PCB boards. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology