Transmission Substrate Etching Layout for Uniform Impedance
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Solution Overview
Problem
Existing methods for producing high-speed transmission boards with high-frequency signal paths face challenges in maintaining uniform impedance across multiple boards produced from a single panel, due to variations in wet etching processes.
Innovation Solution
A transmission board production method involving a resist formation step, exposure, resist removal, and wet etching, where the photomask is designed to ensure uniform etching speeds along each transmission path by maintaining or removing copper foil in a controlled manner, preventing mixing of areas with and without copper foil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmission boards are produced from a single panel using conventional photomask patterns, then production efficiency is improved, but impedance uniformity deteriorates due to mixed copper foil areas causing varying etching speeds
Solution Approach 1:
The photomask pattern is designed to segment the copper foil areas into distinct regions around each transmission path. This segmentation prevents the mixing of copper foil areas during etching, ensuring that each transmission path experiences uniform etching conditions and maintains consistent impedance characteristics across multiple boards produced from a single panel
Solution Approach 2:
The photomask is configured to provide different copper foil area configurations at different locations on the panel. Specifically, each transmission path is surrounded by copper foil in a controlled manner to create uniform etching environments locally, while maintaining overall production efficiency from a single panel
2Device complexity
If the photomask allows copper foil areas to mix during etching, then manufacturing complexity is reduced, but etching speed uniformity deteriorates leading to impedance variations
Solution Approach 1:
The photomask pattern segments the copper foil into distinct non-mixing areas around each transmission path. This segmentation maintains relatively simple photomask design while preventing the mixing of copper foil areas that would cause etching speed variations and impedance inconsistencies
Solution Approach 2:
The photomask is designed in advance to pre-establish the copper foil area configuration that will ensure uniform etching speeds. By preliminarily configuring the copper foil areas to not mix during etching, the system achieves etching speed uniformity without requiring complex real-time control during the etching process
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 method effectively suppresses variations in impedance across multiple transmission boards produced from a single panel, ensuring that the impedances remain close to the design value, thereby improving production consistency and efficiency.
Implementation Method 1
an exposure step of irradiating the photoresist with light via a photomask
Implementation Method 2
an etching step of performing wet etching at a part, of the copper foil, exposed through the resist removal step, using an etching solution
Data Source
AI summary
This transmission board production method is for producing a plurality of transmission boards from a panel having a copper foil on a surface thereof, the plurality of transmission boards each including a transmission path, the transmission board production method including: a resist formation step of forming a photoresist on the copper foil; an exposure step of irradiating the photoresist with light via a photomask; a resist removal step of removing, of the photoresist, either of a part irradiated with the light and a part not irradiated with the light; and an etching step of performing wet etching at a part, of the copper foil, exposed through the resist removal step, using an etching solution. The photomask includes a pattern for forming the transmission path included in each of the plurality of transmission boards, so that the transmission paths are along each other. The photomask is formed so that, of the copper foil, a part around each of a plurality of the transmission paths to be formed through the etching step is removed or remains such that a part where the copper foil remains and a part where the copper foil does not remain are not mixed, through the etching step. In the etching step, the etching solution moves relative to the panel along each transmission path to be formed through the etching step.