How are the first, second and third levels of HDI PCB distinguished? Detailed case description

The first-order is relatively simple, and the process and craftsmanship are well controlled. The second order started to be troublesome, one was the alignment problem, and the other was the problem of punching and copper plating. There are many types of second-order designs. One is that the positions of each step are staggered. When connecting the next adjacent layer, it is connected in the middle layer through a wire, which is equivalent to two first-order HDIs. The second is that the two first-order holes overlap, and the second-order is achieved by superposition. The processing is similar to two first-order, but there are many process points to be specially controlled, which is mentioned above. The third is to punch directly from the outer layer to the third layer (or N-2 layer). The process is different from the previous one, and the difficulty of punching is also greater. For the third-order analogy, it is the second-order analogy.

Examples are as follows:

The first order and the second order of the 6-layer boards are for the boards that require laser drilling, that is, the HDI board.

The 6-layer first-order HDI board refers to blind holes: 1-2, 2-5, 5-6. That is, 1-2, 5-6 need laser drilling.

6-layer second-order HDI board refers to blind holes: 1-2, 2-3, 3-4, 4-5, 5-6. That is, 2 laser drilling is required. First, drill 3-4 buried holes, and then press 2-5, then drill 2-3, 4-5 laser holes for the first time, then press 1-6 for the second time, then drill 1-2, 5-6 laser holes for the second time. Finally, drill through Hole. It can be seen that the second-order HDI board has been pressed twice and laser drilled twice.

In addition, the second-order HDI board is also divided into: wrong hole second-order HDI board and stacked hole second-order HDI board. The wrong hole second-order HDI board means that the blind holes 1-2 and 2-3 are staggered, and the stacked hole second-order HDI board Board refers to the blind holes 1-2 and 2-3 stacked together, for example: blind: 1-3, 3-4, 4-6.

And so on, third-order, fourth-order...all are the same.

The number of steps refers to the number of presses.

The first-order board, once pressed together, can be imagined as the most common board

Second-order board, press twice, take the eight-layer board with blind buried holes as an example, first make a 2-7 layer board, press it, at this time the 2-7 through-holes and buried holes have been completed, and then add 1 Layer and 8 are laminated, and 1-8 through holes are punched to make a whole board.

The third-order board is more complicated than the above, first press 3-6 layers, then add 2 and 7 layers, and finally add 1 to 8 layers, a total of three times, which ordinary manufacturers can't do.