Resistance Alloy Paste Adhesion on Glass Ceramic Substrates
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Solution Overview
Problem
Existing methods for applying resistance alloys to glass or ceramic substrates using pastes result in low adhesion, which compromises the mechanical stability and electrical properties of the layer structure, especially when glass frit is added, altering the temperature coefficient of electrical resistance (TCR) values.
Innovation Solution
A method involving two pastes is used: Paste A with a glass frit and organic medium applied first, followed by Paste B containing resistance alloy powder and a limited amount of glass frit, ensuring strong adhesion without altering the TCR values, achieved by careful selection of glass frit composition and firing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass frit is added to resistance alloy paste to improve adhesion, then adhesion strength is improved, but TCR value deviates from original material properties
Solution Approach 1:
The paste is divided into two separate applications: Paste A containing only glass frit and organic medium applied first, followed by Paste B containing resistance alloy powder with minimal glass frit (0-15 wt%). This segmentation allows the glass frit to provide adhesion without significantly altering the TCR of the resistance alloy layer.
Solution Approach 2:
Glass frit is concentrated in Paste A at the substrate interface where adhesion is needed, while Paste B contains minimal glass frit (0-15 wt%) to maintain the electrical properties of the resistance alloy. This local concentration strategy ensures adhesion strength without compromising TCR precision.
2Ease of manufacture
If resistance alloy paste is applied directly to ceramic substrate, then application process is simple, but adhesion is poor
Solution Approach 1:
Paste A containing glass frit is applied and fired first to create a glass-containing intermediate layer on the ceramic substrate. This preliminary action prepares the substrate surface to provide strong adhesion for the subsequent resistance alloy paste application, eliminating the need for complex surface treatments.
Solution Approach 2:
A glass-containing intermediate layer is introduced between the ceramic substrate and the resistance alloy paste. This intermediate layer acts as a mediator that chemically or physically bonds to both the substrate and the resistance alloy, providing strong adhesion while maintaining process simplicity.
3Strength
If glass frit content in paste B is increased to improve adhesion, then adhesion strength is improved, but TCR value is altered
Solution Approach 1:
The glass frit content in Paste B is precisely controlled within 0-15 wt%, representing an optimized parameter range that provides sufficient adhesion while minimizing impact on TCR. This parameter optimization allows the paste to achieve both adhesion and electrical property stability.
Solution Approach 2:
Instead of using high glass frit content for maximum adhesion, a limited amount (0-15 wt%) is used in Paste B, which is sufficient for practical adhesion requirements while preserving the resistance alloy's electrical properties. The primary adhesion function is fulfilled by Paste A.
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 method produces a layer structure with improved mechanical stability and long-term adhesion without affecting the TCR values of the resistance alloy, allowing for flexible layer geometries and precise resistor production.
Implementation Method 1
a glass frit containing at least two different elements as oxides and having a transformation temperature Tg in the range of 600 to 750°C
Implementation Method 2
During firing, the components of the organic medium evaporate, leaving behind the molten or sintered resistance alloy powder
Implementation Method 3
leaving behind the molten or sintered resistance alloy powder
Data Source
AI summary
The present invention relates to a layered structure comprising: a substrate with a glass or ceramic surface, a layer A that at least partially covers the glass or ceramic surface of the substrate, wherein layer A comprises a glass containing at least two different elements as oxides, and a layer B that at least partially covers layer A. Layer B comprises the following components: a resistance alloy with a temperature coefficient of electrical resistance of less than 150 ppm/K, and optionally a glass containing at least two different elements as oxides. Layer B contains not more than 20% glass by weight, based on the total weight of layer B.