Metal Oxide Thermistor Composite for Low-Temperature Dense Bonding
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Solution Overview
Problem
Existing methods for producing thin-film thermistors with metal oxide films face challenges in achieving strong bonding and desired electrical characteristics due to issues like interfacial detachment and low-quality films formed at low temperatures, while high-temperature sintering leads to cracks and high-temperature processes are unsuitable for mass production.
Innovation Solution
A composite of metal oxide particles with a first amorphous phase containing the same metal elements, combined with a bonding layer of a second amorphous phase, allows for strong bonding and desired electrical characteristics, using a cold sintering process at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering is used to form metal oxide film, then thermistor properties are improved, but bonding strength deteriorates due to thermal expansion mismatch
Solution Approach 1:
The invention changes the sintering temperature parameter from high temperature (400°C or above) to low temperature (below 400°C), specifically using cold sintering at room temperature or slightly elevated temperatures. This parameter change allows the metal oxide particles to be sintered without experiencing thermal expansion mismatch, thereby maintaining bonding strength while still achieving desired thermistor properties through the cold sintering process
Solution Approach 2:
The invention uses a composite material approach by combining metal oxide particles with a binder material that facilitates cold sintering. The binder acts as a matrix that holds the metal oxide particles together at low temperatures, creating a composite structure that achieves both good bonding strength and acceptable thermistor properties without requiring high-temperature sintering
2Temperature
If cold sintering is used to improve bonding strength, then manufacturing temperature is reduced, but film density deteriorates
Solution Approach 1:
The invention introduces a binder as an intermediary material that enables the cold sintering process. The binder serves as a medium that facilitates particle bonding at low temperatures by providing adhesion between metal oxide particles, compensating for the lack of thermal energy that would normally drive densification. This intermediary allows cold sintering to produce films with acceptable density despite the low processing temperature
3Productivity
If low-temperature processes are used to avoid substrate damage, then production speed is improved, but film quality deteriorates
Solution Approach 1:
The invention changes the fundamental approach to low-temperature film formation by using cold sintering with binder materials, rather than conventional low-temperature deposition methods. This parameter change in the sintering process enables the formation of dense, high-quality metal oxide films at low temperatures, achieving both good film quality and acceptable production speed by eliminating the need for high-temperature thermal processes
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 composite achieves dense, strong bonding and maintains electrical characteristics under hot and humid conditions, enabling a thermistor with high reliability and reduced resistance variations, suitable for mass production.
Implementation Method 1
cold sintering (CS), by which metal oxide particles can be sintered at as low temperatures as 200°C or below
Implementation Method 2
a first amorphous phase that is present between the plurality of first particles and contains a metal element or elements of the same kind or kinds as the first metal element
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5(a)~5(b)
AI summary
A novel metal oxide composite is realized in which the metal element(s) in the metal oxide includes at least one of Mn or Ni and that is dense and strong in itself. The composite includes multiple first particles that are particles of a metal oxide containing at least one metal element and a first amorphous phase that is present between the multiple first particles and contains metal element(s) of the same kind(s) as the first metal element. The first metal element includes at least one of Mn or Ni.