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Types of HDI Stackups

There are several types of HDI stackups, or classes, that you may want to use for your design.

0-N-0 with Laser Microvias

In this stack up, the manufacturing steps are as follows:
  1. Core is laminated
  2. Core is mechanically drilled
  3. Mechanical drill is plated
  4. Laser Drilled Vias are formed
  5. Final through hole via is formed

1-N-1 with Laser Microvia and Mechanical Buried Core Via

In a 1-N-1 stackup, the '1' represents one sequential lamination on either side of the core. 1 sequential lamination adds two copper layers for a total of 4 layers and there are no stacked vias.

In this stack up, the manufacturing steps are as follows:
  1. Core is laminated
  2. Core is mechanically drilled
  3. Mechanical drill is plated
  4. Inner layer is created
  5. Sequential lamination adds two additional layers.
  6. Mechanical drill is now a buried via
  7. Laser Drilled Vias are formed
  8. Final through hole via is formed

1-N-1 with Microvia Stacked on Top of Buried & Filled Core Via

In a 2-N-2 stackup, the '2' represents two sequential laminations.

As stated above, 1 sequential lamination adds two copper layers, so 2 sequential laminations adds 4 copper layers for a total of 6 layers. Again, there are no stacked vias.

2-N-2 with Stacked Microvias and Buried Core Via

This stackup is similar to the one above, except in this case there are stacked microvias.

Because of the stacked microvias, a couple things need to happen: the microvia needs to be plated with copper and planarized flat.