Circuit Board Metal Foil Plating for Trace Thickness Control
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Solution Overview
Problem
Existing techniques for forming conductive layers with varying trace thicknesses on circuit boards are costly and prone to non-uniformity, making it difficult to optimize routing density for both high-speed and low-speed signals.
Innovation Solution
A method involving the application of metal foil to an insulating layer, selective plating with additional metal, and controlled removal of metal foil to create conductive traces of varying thicknesses, followed by lamination with a second insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thicker metal foils are used to create varying trace thicknesses through selective etching, then signal integrity and power delivery are improved, but manufacturing cost increases and manufacturing precision deteriorates due to difficulty in controlling metal thickness
Solution Approach 1:
Instead of starting with thick metal and removing material through etching, the patent applies thin metal foil first and then selectively adds metal through electroplating. This inversion of the traditional approach allows precise control over final trace thickness while maintaining uniformity, as the plating process can be precisely controlled to add only the required amount of metal in specific areas.
Solution Approach 2:
The patent creates traces with varying thicknesses by applying different amounts of electroplated metal to different regions of the circuit board. Critical signal traces receive thicker plating for enhanced signal integrity, while non-critical areas maintain thinner traces for optimal routing density. This local differentiation of metal thickness achieves the desired performance characteristics without compromising manufacturing precision.
2Reliability
If thicker metal foils are used for all traces, then signal integrity is improved, but routing density decreases
Solution Approach 1:
The patent selectively applies electroplating to create thicker traces only in regions where signal integrity is critical, while leaving other regions with thinner traces to maximize routing density. This localized differentiation allows the circuit board to achieve both high signal integrity for critical paths and high routing density for non-critical connections within the same layer.
Solution Approach 2:
The patent varies the metal thickness parameter across different regions of the circuit board by controlling the electroplating process. By adjusting plating time, current density, and resist mask patterns, the patent creates a distribution of trace thicknesses that optimizes both signal integrity and routing density according to the specific requirements of different circuit regions.
3Adaptability or versatility
If controlled chemical etching is used to create varying trace thicknesses, then trace thickness variation is achieved, but manufacturing complexity increases and manufacturing precision deteriorates
Solution Approach 1:
The patent inverts the traditional etching approach by using electroplating instead. Rather than removing metal to create thickness variations, the patent deposits metal selectively onto a uniform thin foil substrate. This inversion provides superior control over thickness uniformity because the plating process can be precisely controlled through electrical parameters, avoiding the non-uniformity inherent in chemical etching processes.
Solution Approach 2:
The patent replaces the chemical etching process with an electroplating process. Instead of using chemical reactions to remove metal and create thickness variations, the patent uses controlled electrochemical deposition to add metal selectively. This substitution of the manufacturing mechanism provides better control over thickness precision and reduces manufacturing complexity.
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 allows for the creation of circuit boards with optimized routing density and signal integrity, reducing the challenges of non-uniformity and cost associated with traditional methods.
Implementation Method 1
selectively plating the layer of metal with additional metal
Data Source
AI summary
A method for forming a circuit board may include, in a conductive layer of the circuit board, applying a layer of metal foil to a first insulating layer of the circuit board, selectively plating the layer of metal with additional metal, removing portions of the layer of metal foil such that the selectively plating and removing steps create a plurality of conductive traces including a first conductive trace and a second conductive trace within a conductive layer of the circuit board, wherein a first thickness of the first conductive trace from a surface of the first insulating layer is different than a second thickness of the second conductive trace from the surface, and laminating a second insulating layer over the conductive layer.