Wiring Board Line Conductor Width Variation for Platinum Sublimation
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Solution Overview
Problem
Wiring boards used for temperature detection in high-temperature environments face accuracy issues due to changes in electric resistance values caused by factors other than temperature, primarily due to platinum sublimation from the insulating substrate.
Innovation Solution
The wiring board design features line conductors with increased width in interlayers closest to the substrate surfaces, where sublimation occurs most easily, and a meander-shaped pattern with wider line widths facing the substrate, minimizing the relative reduction of platinum and thus stabilizing the electric resistance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line conductors are disposed in interlayers of insulating layers, then the wiring board structure is formed, but platinum sublimation occurs through the insulating substrate causing change in electric resistance value
Solution Approach 1:
The patent applies local quality by making the line width of the outermost line conductor different from the inner line conductors. Specifically, the outermost line conductor has a larger line width than the inner line conductors. This local variation in geometry compensates for the platinum loss occurring at the outer surfaces exposed to sublimation, maintaining the overall electric resistance stability.
2Reliability
If platinum is used for line conductors, then oxidation resistance and temperature dependence are improved, but platinum escapes through insulating substrate at high temperatures
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the line conductors. The outermost line conductors are designed with larger line widths compared to inner line conductors. This parameter adjustment compensates for the expected platinum loss during high-temperature operation, ensuring that the electric resistance value remains stable despite the inherent platinum sublimation that occurs even with oxidation-resistant materials.
3Measurement precision
If detection accuracy is maintained over long term, then temperature sensing reliability is improved, but platinum sublimation degrades detection accuracy
Solution Approach 1:
The patent applies preliminary action by pre-compensating for the expected platinum sublimation loss through the design of asymmetric line widths. Before the sensor is put into service, the outermost line conductors are designed with larger cross-sections to anticipate and offset the future material loss. This preliminary geometric adjustment ensures that the electric resistance remains stable throughout the long-term operation, maintaining temperature detection accuracy without degradation over time.
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 maintains high detection accuracy for temperature changes over time by reducing the impact of platinum sublimation on the electric resistance value, ensuring reliable temperature sensing in high-temperature environments.
Implementation Method 1
a sensor is known that utilizes a temperature-dependent change in the electric resistance value of a metallic material
Implementation Method 2
a part of the platinum or the like forming the line conductors escapes (e.g., sublimates) through the inside of the insulating substrate to the outside
Data Source
AI summary
A wiring board includes an insulating substrate composed of a stack of a plurality of insulating layers, the insulating substrate having an upper face, a lower face, and side faces; and a plurality of line conductors formed of platinum or a metallic material comprising platinum as a main component, the plurality of line conductors each including a first end and a second end located on a side opposite to the first end, the plurality of line conductors being respectively disposed in interlayers between the plurality of insulating layers, in the line conductors, a line width of a line conductor located in an interlayer among the interlayers which interlayer is closest to the upper face or the lower face of the insulating substrate being greater than a line width of a line conductor located in each of the other interlayers.