Identify the space you recover

Compare the proposed pad-centered transition with an offset escape at the actual package geometry. Include the track segment, neighboring pad clearance, solder mask, and target-layer routing. If moving the via does not open a usable channel or improve a necessary current path, the additional processing may have little benefit.

Keep the component land requirements visible during this study. Modifying a land solely to accommodate a chosen via can trade a routing improvement for an assembly problem.

State the finished surface

A via location and hole size do not tell an assembler what the solderable surface will look like. Identify fill, cap or overplate requirements where applicable, and the acceptance of surface recess or protrusion. Confirm which requirements apply to microvias and which apply to larger plated holes.

Texas Instruments' PoP assembly guidance addresses a specific fine-pitch package context. Use package-specific guidance as an input to assembly planning, while confirming the land and via treatment for your exact device and production process.

Review an entire solder joint location

For an illustrative processor redesign, an offset via is moved into a central BGA land. Review the package land, mask opening, final finish, via treatment, paste strategy, and thermal profile together. Approving only the bare-board cross-section leaves the assembled joint condition unresolved.

  • Make the via-in-pad locations identifiable in fabrication notes.
  • Distinguish solder lands from nonsoldered copper connection pads.
  • Ask the assembler to review the finished land condition.
  • Define how first-build assembly findings will be captured.

Avoid shorthand that hides different processes

Terms such as plugged, tented, filled, capped, and copper-filled are not interchangeable instructions. Describe the result required and agree on the process terminology used by the supplier. If a quoting system offers a single via-in-pad checkbox, supplement it with a drawing that removes ambiguity.

DESIGN NOTE / SCHEMATIC

Adjacent-layer access, one connection at a time

Signal copper

Dielectric · geometry + material

Reference copper

Core or build-up dielectric

Signal copper

Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.

Common questions

Is solder mask tenting a substitute for a finished pad surface?

No. A mask covering and a solderable filled-and-finished structure serve different purposes. Select the treatment for the intended assembly location.

Should every BGA land contain a via?

No. Use via-in-pad where the escape or electrical requirement benefits. Additional via locations can complicate fabrication without helping routing.

References & further reading

Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.