Circuit Board Conductive Pillar Layout Density
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Solution Overview
Problem
Current circuit board structures face challenges in achieving high circuit layout density, reliability, and simplicity in the fabrication process due to the use of annular metal rings for electrical connections, which limit space and introduce materials with different thermal expansion coefficients, leading to delamination and complexity.
Innovation Solution
A circuit board structure featuring a conductive pillar formed by electroplating within a through hole of a carrier board, with end portions protruding above the surfaces and directly connected to circuit layers, eliminating the need for annular metal rings and filling materials, thereby increasing layout density and reducing fabrication complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plated through hole with annular metal ring is used to connect circuit layers, then electrical connection is achieved, but the diameter of the annular metal ring must be greater than the plated through hole diameter, which limits circuit layout density and increases spacing between adjacent connections
Solution Approach 1:
The invention extracts and eliminates the annular metal ring from the traditional plated through hole structure. Instead of using a ring-shaped conductor, a solid conductive pillar is formed directly in the through hole, removing the unnecessary annular structure that constrained layout density while maintaining electrical connection functionality.
Solution Approach 2:
The invention changes the geometric parameter of the conductor from an annular shape with inner/outer diameters to a solid cylindrical pillar with a single diameter. This parameter change allows the conductor diameter to be equal to or slightly larger than the through hole diameter, eliminating the spacing constraint imposed by traditional annular rings.
2Reliability
If filling material is used to fill plated through holes, then electrical connection is achieved, but multiple materials with different coefficients of thermal expansion are introduced, causing delamination and reducing reliability
Solution Approach 1:
The invention removes the filling material step from the fabrication process. Instead of filling the through hole with dielectric or conductive paste and then removing excess material, a conductive pillar is formed directly in the through hole using electroplating, eliminating the need for filling and subsequent buffing operations.
Solution Approach 2:
The electroplating process automatically forms the conductive pillar with the correct dimensions and shape without requiring additional filling materials or buffing operations. The process is self-regulating, depositing metal only where needed on the through hole walls and creating a uniform pillar structure.
3Reliability
If filling material is used in plated through holes, then electrical connection is achieved, but the filling material is easy to absorb moisture, decreasing circuit board quality
Solution Approach 1:
The invention eliminates the filling material that is prone to moisture absorption. The through hole is filled with a conductive pillar formed by electroplating, which uses metals (copper, nickel, palladium, silver) that do not absorb moisture, thereby removing the source of moisture-related quality degradation.
Solution Approach 2:
The invention changes the material composition from moisture-absorbing dielectric or conductive paste to moisture-resistant metallic materials through electroplating. This material parameter change fundamentally alters the moisture absorption characteristic from high to low, improving circuit board quality.
4Reliability
If the diameter of the annular metal ring is increased to ensure alignment accuracy, then connection reliability is improved, but the spacing between adjacent plated through holes cannot be reduced, preventing high density circuit layout
Solution Approach 1:
The invention changes the conductor geometry from annular to cylindrical, allowing the diameter parameter to be optimized for alignment accuracy without the constraints of traditional ring structures. The solid pillar can have a diameter equal to or slightly larger than the through hole, enabling tighter spacing between adjacent connections while maintaining alignment reliability.
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
This approach enhances circuit layout density, improves reliability by avoiding delamination, and simplifies the fabrication process by eliminating the need for filling materials and annular metal rings, resulting in a more reliable and efficiently manufactured circuit board.
Implementation Method 1
a conductive pillar formed in the through hole by electroplating and having end portions protruding above the first and second surfaces of the carrier board
Data Source
AI summary
The present invention provides a circuit board structure, the circuit board structure consisting of a carrier board having a first surface and an opposed second surface, the carrier board being formed with at least one through hole penetrating the first and second surfaces; a conductive pillar formed in the through hole by electroplating; and a first circuit layer and a second circuit layer respectively formed on the first and second surfaces of the carrier board, the first and second circuit layers being electrically connected to the two end portions of the conductive pillar, thereby reducing spacing between adjacent conductive pillars of the carrier board and achieving high density circuit layout.