Describe where the connection goes
A blind via connects an outer layer to an internal layer. A buried via connects internal layers without reaching the finished outer surfaces. A through via spans the board. These location terms do not by themselves define a fabrication method or establish a supplier's process limit.
Altium's via documentation distinguishes these structures and describes microvias in sequential buildup. For a real design, pair the name with explicit start and stop layers. A via map is more precise than a note saying use HDI vias.
Describe how buildup connections are arranged
Stacked microvias are aligned across successive buildup levels; staggered microvias are offset between levels. Sequential buildup refers to constructing layers through successive manufacturing stages. Any-layer HDI commonly describes an architecture offering microvia based connections across the layer structure, but the exact proposed build still needs a drawing.
Do not read these words as reliability rankings independent of geometry and process. Ask which arrangement is actually required by the routing and what manufacturing evidence applies to it. Terminology narrows the question; it does not answer qualification.
Separate design geometry from acceptance evidence
A stackup documents the layer construction. A coupon is a test structure selected to represent particular features. An impedance coupon and a microvia reliability coupon serve different purposes. A microsection is a prepared cross sectional specimen used to inspect internal structure; its interpretation depends on the specified criteria.
| Term in discussion | Useful follow-up |
|---|---|
| Aspect ratio | Which depth and diameter definitions are used? |
| Via in pad | What filling, capping and assembly requirements apply? |
| Controlled impedance | Which geometry, layers, target and measurement method? |
| Approved material | Which product and construction are authorized? |
Use precise language in purchasing
Define DFM as the manufacturability review being requested and list its intended scope. Define first article by the product boundary being inspected. Identify the applicable standard and revision when requesting a class or acceptance level. These additions prevent familiar abbreviations from concealing different expectations.
When a supplier uses an unfamiliar term, ask for the relevant cross section or process explanation and add the agreed meaning to the project record. A shared drawing usually resolves ambiguity more effectively than debating shorthand.
Adjacent-layer access, one connection at a time
Dielectric · geometry + material
Core or build-up dielectric
Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.
Common questions
Is a blind via always a microvia?
No. Blind describes where a via begins and ends. Confirm the structure, geometry and process rather than treating the terms as interchangeable.
Does any-layer mean every possible via span is automatically allowed?
No. The actual stackup, fabrication sequence and approved via structures determine which connections can be built. Use the supplier reviewed via map.
References & further reading
Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.