How to distinguish the first, second and third order of HDI PCB

The first order is relatively simple, and the process and the process are well controlled.

The second problem started to become troublesome, one was the alignment problem, and the other was the stamping and copper plating problem. There are many second-order designs. One is the staggered position of each step. When connecting the next adjacent layer, the wires are connected to the middle layer. This is equivalent to two first-order HDIs.

The second is that the two first-level holes overlap, and the second-level is realized by superposition. The processing is similar to the two first-order, but there are many technical points that require special control, as described above.

The third is to punch holes directly from the outer layer to the third layer (or N-2 layer). The process is very different from the previous one, and punching is more difficult.

For the third order, the second order analogy is.

The ordinary PCB board is mainly FR-4, which is made of epoxy resin and electronic grade glass cloth. Generally, traditional HDI uses bonded copper foil on the outermost surface. The glass cloth cannot be opened due to laser drilling. Therefore, bonded copper foil without glass fiber is usually used, but now high-energy laser drills can penetrate 1180 glass cloth. This is no different from ordinary materials.