Printed Wiring Board Resistor Stability via Spaced Undercoat
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Solution Overview
Problem
Conventional printed wiring boards (PWBs) with resistor elements face issues of resistance value fluctuation due to electron migration and corrosive reactions between the resistor and conductive patterns, as well as disfigurement during lamination, leading to unstable resistance values.
Innovation Solution
A PWB design with a resistor element embedded in an insulation layer, where the resistor is separated by a space from the external connection conductive pattern, using nickel electrodes with phosphorus content for corrosion resistance and even surfaces, and a thickness less than the conductive layer to prevent disfigurement and pressure-induced fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the resistor is formed close to the conductive pattern to save space, then the device complexity is reduced, but electron migration and corrosive reactions occur between the resistor and conductive pattern
Solution Approach 1:
An undercoat layer is introduced as an intermediary between the resistor and the conductive pattern. This undercoat layer acts as a barrier that prevents direct contact between the resistor material and the conductive pattern, thereby stopping electron migration and corrosive reactions while allowing the resistor to be positioned close to the conductive pattern for space efficiency.
2Measurement precision
If the resistor thickness is increased to improve resistance accuracy, then the measurement precision is improved, but the resistor becomes prone to disfigurement during lamination and pressure-induced fluctuations
Solution Approach 1:
The thickness of the resistor is optimized to a specific range that balances resistance accuracy with manufacturing integrity. By carefully controlling the resistor thickness parameter within an optimal range, the patent achieves sufficient resistance precision while preventing disfigurement during lamination and pressure-induced fluctuations.
Solution Approach 2:
The undercoat layer serves as a cushioning layer that protects the resistor from direct pressure during lamination processes. This preliminary protective layer prevents disfigurement of the resistor while allowing the resistor to maintain its functional thickness for accurate resistance values.
3Reliability
If the conductive pattern thickness is increased to improve conductivity, then the electrical conductance is improved, but the resistance value fluctuates due to pressure during lamination
Solution Approach 1:
The undercoat layer acts as a mediator that decouples the conductive pattern from the resistor, preventing direct pressure transmission during lamination. This allows the conductive pattern to have sufficient thickness for good conductivity while maintaining consistent resistance values by eliminating pressure-induced fluctuations.
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
The solution stabilizes resistance values by preventing electron migration and corrosive reactions, reducing the impact of conductive pattern thickness variations, and enhancing corrosion resistance, resulting in a highly accurate and reliable resistor element with minimal resistance fluctuations.
Implementation Method 1
using nickel electrodes with phosphorus content for corrosion resistance
Implementation Method 2
forming electrodes on a conductive layer formed on a substrate by a plating method
Data Source
AI summary
A manufacturing method of a printed wiring board, including forming a plurality of electrodes on a conductive layer formed on a substrate by a plating method, forming an insulation layer on the electrodes and the conductive layer, removing the substrate from the conductive layer, patterning the conductive layer except for a resistor forming region reserved for forming a resistor, thereby forming an external connection conductive pattern, and forming a resistor in the resistor forming region such that the resistor is separated by a space from the external connection conductive pattern.