The first-order HDI PCB circuit board is relatively simple, and the process and process are easy to control.
The second-order HDIPCB circuit board began to be troublesome, one was the alignment problem, and the other was the hole punching and copper plating problem. There are many second-order designs. One is that the positions of each stage are staggered, and when the next adjacent layer needs to be connected, it is connected through a wire in the middle layer. The method is equivalent to two first-order HDIs. The second is that two first-order holes overlap, and the second-order is realized by superposition. The processing is similar to the two first-order holes, but there are many process points that need to be specially controlled, which is the above mentioned. The third is to punch holes directly from the outer layer to the third layer (or N-2 layer). The process is much different from the previous one, and the difficulty of punching is also greater.
For the third order, it is to the second order.
Examples are as follows:
The first-order and second-order of 6-layer circuit boards are for PCB boards that require laser drilling, that is, HDI boards. The first-order HDI boards of 6-layer circuit boards refer to blind holes: 1-2, 2-5, 5- 6. That is, 1-2, 5-6 need laser drilling.
The second-order HDI board of 6-layer circuit board refers to blind holes: 1-2, 2-3, 3-4, 4-55-6. It needs 2 times of laser drilling. First drill 3-4 buried holes, and then press them 2-5, then drill 2-3, 4-5 laser holes for the first time, then press 1-6 for the second time, and then drill 1-2, 5-6 laser holes for the second time. Finally, drill through holes. 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: the second-order HDI board with staggered holes and the second-order HDI board with stacked holes. The second-order HDI board with staggered holes means that blind holes 1-2 and 2-3 are staggered, and the second-order HDI board with stacked holes The board refers to the stacking of blind holes 1-2 and 2-3, for example: blind: 1-3, 3-4, 4-6.
the third order, the fourth order... are all the same. The number of steps refers to the number of presses.
The first-order PCB board can be assembled once, and it can be imagined as the most common PCB circuit board.
The second-order PCB board is laminated twice, taking the eight-layer circuit board with blind buried holes as an example. First make the 2-7 layer circuit board and press it; at this time, the 2-7 through-hole buried holes have been prepared. Add 1 layer and 8 layers to laminate, and punch 1-8 through holes to make the whole board.
The third-order PCB 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. It needs to be pressed three times in total, which is generally impossible for circuit board manufacturers.
