The difference between HDI board and blind buried hole circuit board

HDI is a board product called high density interconnect. Currently, advanced electronic products are generally HDI board products.
Blindvias: Blindvias: Blindvias is the type of hole that connects the internal wires of the PCB to the surface lines of the PCB. This hole does not penetrate the entire board.
Buried hole: A buried hole is a type of hole that connects only the wires between the inner layers, so they are not visible from the surface of the PCB.
As portable products move toward miniaturization and high density, PCB design becomes more and more difficult, which puts higher demands on the PCB production process. In most portable products, the BGA package with a 0.65mm pitch is based on a blind buried hole design process. What is a blind hole?
Blindvias: Blindvias: Blindvias is the type of hole that connects the PCB's internal wiring to the PCB surface. This hole does not penetrate the entire board.
Buried hole: A buried hole is a type of hole that connects only the wires between the inner layers, so they are not visible from the surface of the PCB.
A circuit board with buried blind holes is not necessarily an HDI circuit board, but a general HDI board has blind holes, which are not necessarily determined, depending on the level and pressure of the circuit board product.
Explain as follows:
The first and second orders of the six-layer board are suitable for boards that require laser drilling, ie HDI boards.
Six-layer board first-order HDI board finger blind holes: 1-2, 2-5, 5-6. That is 1-2, 5-6 requires laser drilling.
Six-layer circuit board second-order HDI board finger blind holes: 1-2, 2-3, 3-4, 4-5, 5-6. Two laser drillings are required.
First drill 3-4 buried holes, then press 2-5, drill 2-3 again, 4-5 laser holes for the first time, then press 1-6, then drill 1-2, 5-6 laser Hole in the second time, and finally drill the hole. It can be seen that the second order HDI plate has undergone two presses and two laser drills.
In addition, the second-order HDI board can be divided into: a staggered second-order HDI board and a stacked second-order HDI board. Interlaced second-order HDI boards refer to blind holes 1-2 and 2-3 interleaved, while stacked second-order HDI boards refer to blind holes 1-2 and 2-3 stacked together, for example: blind: 1-3, 3 -4, 4-6.
By analogy, the third and fourth order... it is the same.