3D Copper PCB Structures for High-Current Power Delivery
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Solution Overview
Problem
Conventional PCB architectures face challenges in delivering power to low voltage, high current processors due to limited copper cross-sectional area, leading to increased DC resistance and thermal issues, which are exacerbated by the need for thicker copper planes that restrict design flexibility and increase material and fabrication costs.
Innovation Solution
Implementing 3D conductive material trenches and buried vias in PCBs, formed through laser drilling and electroplating, to increase copper cross-sectional area and reduce DC resistance, while maintaining mechanical strength and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thicker copper planes are used to increase current carrying capacity, then current density limits are satisfied, but design flexibility is restricted and fabrication complexity increases
Solution Approach 1:
The patent transitions from conventional 2D copper traces to 3D copper structures by filling laser-drilled vias with copper to create vertical conductive pathways. This adds a z-dimension to current flow, enabling current to travel through the thickness of the PCB rather than only along the surface, thereby increasing current carrying capacity without requiring thicker copper planes
Solution Approach 2:
The patent embeds copper-filled vias within the PCB structure, nesting conductive elements inside the dielectric layers. The copper fills the void space created by laser drilling, effectively placing conductive material within the existing PCB architecture rather than adding external layers
2Reliability
If thicker copper planes are used to increase current carrying capacity, then current density limits are satisfied, but copper cross-sectional area in the same volume is reduced
Solution Approach 1:
By creating vertical copper pathways through laser-drilled and filled vias, the patent utilizes the z-dimension (through-thickness direction) to increase effective copper cross-sectional area. This allows current to flow through multiple layers simultaneously, increasing carrying capacity without expanding the planar footprint or overall PCB volume
Solution Approach 2:
The patent changes the geometric parameters of copper conductors by creating three-dimensional copper structures with varying cross-sectional areas along the z-axis. The copper-filled vias provide a continuous conductive path that optimizes the distribution of current density across multiple layers, increasing effective area without proportionally increasing volume
3Area of stationary object
If mechanical drilled vias are used for z-axis connections, then larger diameter vias are achieved, but copper plating thickness is limited and current density increases
Solution Approach 1:
The patent replaces mechanical drilling with laser drilling for via formation. Laser drilling creates precise, consistent vias that can be fully filled with copper, whereas mechanical drilling produces larger vias with thinner copper plating that cannot be fully filled. This substitution enables complete copper filling, maximizing the effective copper cross-sectional area and reducing current density
Solution Approach 2:
The patent changes the via formation method from mechanical to laser-based, which alters the via geometry and enables different copper filling approaches. Laser-drilled vias have controlled dimensions that allow complete copper filling, transforming the conductor from a thin-walled structure to a solid copper pillar, thereby increasing effective area and reducing current density
4Manufacturing precision
If laser drilled vias are used for z-axis connections, then smaller diameter vias are achieved, but cross-sectional area is limited and current carrying capacity is reduced
Solution Approach 1:
The patent embeds solid copper within laser-drilled vias, nesting the conductive material inside the precisely-formed via holes. This allows the small, precise via structure to contain a large effective copper cross-sectional area, combining the precision of laser drilling with the high current capacity of substantial copper volume
Solution Approach 2:
The patent creates a composite structure combining the dielectric material of the PCB with embedded copper conductors. The laser-drilled via provides a precise cavity that is completely filled with copper, creating a composite conductor-dielectric structure that maximizes current carrying capacity within the constrained via dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances current carrying capacity, reduces DC resistance, and improves thermal management, allowing for higher current densities within maximum limits, thus supporting reliable operation of low voltage, high current technologies with reduced material usage and fabrication complexity.
Implementation Method 1
Overlapping holes may be formed in a dielectric layer of one or more build-up layers using a laser drill
Implementation Method 2
The holes and/or trenches may be filled with conductive material using a combination of electroless and electrolytic plating of conductive material
Data Source
AI summary
Structures that implement three-dimensional (3D) conductive material (e.g., copper) in printed circuit boards (PCBs) are disclosed. 3D (three-dimensional) conductive material may include trenches and/or buried vias that are filled with conductive material in the PCBs. Trenches may be formed in build-up layers of a PCB by overlapping multiple laser drilled vias. The trenches may be filled with conductive material using electroplating process(es). Buried vias may be formed through the core layers of the PCB by mechanical drilling. The buried via may be filled with solid conductive material using a combination of electroless plating and electrolytic plating of conductive material. Various PCB structures are disclosed that implement combinations of these trenches and/or these buried vias filled with conductive material.