Alcanta PCB company is one of the Blind Vias pcb manufacturer.we have made many PCB with Buried and Blind Vias holes, Impedance Control with +/-5%, Hybrids & Mixed Dielectrics, Non‐Conductive Via Fill, Conductive Via Fill , Cavity Boards, Backdrilling, Controlled Depth Drill and Rout and other many especial design.
Blind Vias and buried vias
Due to the increasing complexity of the design structure, more and more blind holes and buried holes are used in high density circuit board (hdi-pcb). Blind holes and buried through holes are used to connect PCB layers with limited space. A blind hole connects the outer layer of one or more inner layers but does not go through the entire plate. The armour is buried via at least two inner layers, which are not visible from the outer layer. This technology can achieve more functions with less board space (package density).
Not all combinations are possible.
Blind hole and buried hole will greatly increase the cost of PCB. They should only be used when absolutely necessary. To help the designers of the compact plate, we provide through holes below 0.15 mm in the summary service, while the through holes of 0.10 mm are provided in the non buffering option. They require a minimum outer pad size of 0.45 mm and 0.40 mm, respectively.
Use the smart menu build wizard to examine which blind hole and flush hole options can be generated for your design and determine their cost. Choose from more than 700 preset multi-layer structures, accessible by number of layers, plate thickness, structure and copper weight.
Making method of blind hole and buried hole
We don’t use depth controlled laser drilling to make blind and buried holes. We first drill one or more cores and then pass them through the hole. Then we build and press the stack. This process can be repeated several times.
- Through hole must always cut through even number of copper layers.
- The through hole shall not terminate at the top of the core wire
- Vias cannot start from the bottom of the core
- Blind or buried holes cannot start or end in the interior or end of another blind or buried hole, unless one blind hole or buried hole is completely enclosed in the other hole (this will add additional cost because additional stamping cycle is required).
These rules have been merged into the build wizard.
Therefore, in a standard 4-layer construction, we can only drill the embedded vias between layers 2 and 3.
For blind holes, you need to choose reverse build. Here, instead of having a single core in the center between layers 2 and 3, but on the outside of the board, there are two cores between layers 1, 2 and 3 and 4. Now we can drill blind holes between layers 1 and 2 and between layers 3 and 4. Buried holes are no longer available because the dielectric between 2 and 3 is prepreg and cannot be drilled separately.
Higher layers work in the same way, but blind and buried holes can now be combined. Blind and buried holes can overlap as long as one of them is completely enclosed in the other (but pay attention to the additional stamping cycle).