How to make blind&buried vias
Generally We don’t use depth-controlled laser drilling to manufacture blind and buried vias. Firstly we drill one or more cores and plate through the holes. Then we build and press the stack. This process can be repeated several times.
This means:
1. A Via always has to cut through an even number of copper layers.
2. A Via cannot end at the top side of a core
3. A Via cannot start at the bottom side of a core
4. Blind or Buried Vias cannot start or end inside or at the end of another Blind/Buried via unless the one is completely enclosed within the other (this will add extra cost as an extra press cycle is required).
Impedance control
Impedance control has been one of the essential concerns and severe problems in high-speed pcb design.
In high-frequency applications, controlled impedance helps us ensure that signals are not degraded as they route around a PCB.
Resistance and reactance of an electrical circuit have a significant impact on functionality, as specific processes must be completed before others to ensure proper operation.
Essentially, controlled impedance is the matching of substrate material properties with trace dimensions and locations to ensure the impedance of a trace’s signal is within a certain percentage of a specific value.