The printed circuit boards with multi-layer blind buried and blind via structures are generally completed by the "sub-board" production method, which means that it can only be completed after many times of pressing, drilling, hole plating, etc., so the precise positioning is very important.
High-precision printed circuit refers to the use of fine line width/spacing, tiny holes, narrow ring width (or no ring width), and buried and blind vias to achieve high density. And high precision means that the result of "thin, small, narrow, thin" will inevitably bring high precision requirements. Take the line width as an example: 0.20mm line width, 0.16-0.24mm produced according to the regulations is qualified, and the error is (0.20 Soil 0.04) mm; and the line width of 0.10 mm, the error is (0.10+0.02) mm in the same way, obviously the accuracy of the latter is doubled, and so on is not difficult to understand, so the high-precision requirements will not be discussed separately. The combination technology of buried, blind and through-hole (multi-layer blind buried circuit board) is also an important way to improve the high density of printed circuits. Generally, buried and blind vias are tiny holes. In addition to increasing the number of wiring on the circuit board, buried and blind vias are interconnected between the "nearest" inner layers, which greatly reduces the number of through-holes formed, and the setting of isolation pads also will be greatly reduced, thereby increasing the number of effective wiring and interlayer interconnections in the board, and improving the high density of interconnections.
Coincidence between layers in the manufacture of multi-layer circuit boards with blind and buried holes
By adopting the pre-pin positioning system produced by ordinary multi-layer circuit boards, the pattern production of each layer and single piece is unified into one positioning system, which creates conditions for the success of manufacturing. For the ultra-thick single piece like the one used this time, if the thickness of the plate reaches 2 mm, the method of milling a certain thickness layer at the position of the positioning hole can also be classified into the processing of the punching four-slot positioning hole equipment of the front positioning system. in ability.