Heat Dissipation
Vertical interconnect structures facilitate the movement of thermal energy from a surface component to internal copper layers. Within high-power circuit designs, blind thermal vias provide a path for heat to escape from a component pad without passing through the entire thickness of the board. These holes are drilled to a specific depth and plated with copper to form a low-resistance conduit.
Their reach is limited to the layers between the outer surface and the target internal plane.
Fabrication Requirement
Controlled depth drilling or sequential lamination defines the geometry of these conduits. When manufacturing boards with blind thermal vias, the fabricator must ensure that the copper plating inside the hole is thick enough to meet thermal conductivity targets. Filling the vias with conductive or non-conductive epoxy prevents solder from wicking away from the component pad during assembly.
Excessively thin plating leads to localized overheating and potential delamination under high thermal loads. Laser drilling is often employed for smaller diameters to maintain accuracy and avoid damaging the target internal pad. This precision ensures that the thermal path remains intact through multiple reflow cycles.
Application Limit
Performance limits depend on the ratio of hole diameter to depth. Because blind thermal vias do not exit the bottom of the board, they allow for components or traces to be placed directly underneath them on the opposite side. This configuration increases the density of the layout while maintaining thermal management.
Effective cooling requires a sufficient number of these structures to spread the heat across the available copper surface area.
