Printed Wiring Board With Silver Surface Layer for Transmission Loss Reduction

Solution Overview

Problem

Existing printed wiring boards face challenges in improving transmission characteristics, particularly with high-speed signals, due to the skin effect which concentrates current near the surface, leading to increased electrical resistivity and transmission loss.

Innovation Solution

The printed wiring board incorporates a configuration with a main body of a first conductive material (e.g., copper) and a surface layer of a second conductive material (e.g., silver) with lower electrical resistivity, strategically positioned to manage the skin effect and enhance signal transmission, while minimizing increased manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a copper material is used for the wiring pattern, then manufacturing cost is reduced, but transmission loss increases due to the skin effect at high speeds

Engineering Contradiction:

Improvetransmission lossVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies local quality by using different conductive materials at different locations within the wiring pattern. Specifically, a first conductive material (e.g., copper) is used in the lower layer for cost-effectiveness, while a second conductive material (e.g., silver) with lower electrical resistivity is used in the upper layer where the skin effect concentrates high-speed currents. This localized material differentiation optimizes transmission characteristics without unnecessarily increasing overall manufacturing cost.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining multiple conductive materials (copper and silver) within the same wiring pattern structure. The wiring pattern is configured as a multi-layer composite where copper provides the base conductivity and silver enhances high-frequency performance. This composite approach allows the system to achieve both cost-effectiveness and reduced transmission loss by leveraging the complementary properties of different materials.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the entire wiring pattern is made of a material with lower electrical resistivity (e.g., silver), then transmission characteristics improve, but manufacturing cost increases significantly

Engineering Contradiction:

Improvetransmission characteristicsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by using different conductive materials at different locations within the wiring pattern. Specifically, a first conductive material (e.g., copper) is used in the lower layer for cost-effectiveness, while a second conductive material (e.g., silver) with lower electrical resistivity is used in the upper layer where the skin effect concentrates high-speed currents. This localized material differentiation optimizes transmission characteristics without unnecessarily increasing overall manufacturing cost.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by using the expensive low-resistivity material (silver) only partially - specifically in the upper layer where it is most needed for high-speed signal transmission. The lower layer continues to use the cheaper copper material. This partial application of the premium material achieves the necessary transmission characteristics while avoiding the excessive cost of using silver throughout the entire wiring pattern.

Inventive Principle:

Principle #16Partial or excessive action

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 configuration effectively reduces transmission loss and increases signal speed by allowing high-speed currents to flow through the lower resistivity surface layer, improving overall transmission characteristics while maintaining cost-effectiveness.

Implementation Method 1

Existing printed wiring boards face challenges in improving transmission characteristics, particularly with high-speed signals, due to the skin effect which concentrates current near the surface, leading to increased electrical resistivity and transmission loss.

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Data Source

PatentUS11272610B1Printed wiring board, memory system, and method for manufacturing printed wiring board

Publication Date: 2022.03.08 KIOXIA CORP

AI summary

A printed wiring board includes a first insulator, a second insulator, a first conductor, and a second conductor. The first conductor is between the first insulator and the second insulator. The first conductor contains a first conductive material. The second conductor includes a first portion. The first portion is between the first insulator and the first conductor. The first portion is in contact with the first conductor and extends along the first conductor. The second conductor contains a second conductive material. The second conductive material is lower in electrical resistivity than the first conductive material. The second insulator is closer to an outside of the printed wiring board than the first insulator is in a thickness direction of the printed wiring board.