PCB Technical - The difference between HDI board and blind via hole circuit board

HDI is a kind of circuit board product,the full name is high Density Interconnection,high density interconnection board.At present,high-end electronic products are generally HDI board products.

Blind vias:Blind vias are vias that connect the traces on the inner layer of the PCB to the traces on the surface of the PCB board.This hole does not penetrate the entire board.

Buried vias:Buried vias are the type of vias that only connect the traces between the inner layers,so they are invisible from the surface of the PCB plate.

With the current design of portable products moving towards miniaturization and high density,PCB design is becoming more and more difficult, and higher requirements are put forward for the PCB production process.In most of the current portable products,the BGA package with a pitch of less than 0.65mm uses the design process of blind and buried vias.So what is the blind and buried via?

Circuit boards with buried blind vias are not necessarily HDI circuit boards, but generally HDI boards have blind vias, but buried vias are not necessarily the case. It depends on the order and pressure of your circuit board product.

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

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

The 6-layer circuit board 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, 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 for the second time, 5-6 laser holes. Finally, the through holes are drilled. It can be seen that the second-order HDI board has been pressed twice and laser drilled twice.

In addition, second-order HDI boards are also divided into: second-order HDI boards with wrong holes and second-order HDI boards with stacked holes. 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... are all the same.

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