Conductive Paste for Ceramic Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive pastes used for bonding metal parts to ceramic substrates in electronics often face issues with bonding strength, particularly when baked in nitrogen atmospheres, leading to pattern deformation and low productivity.
Innovation Solution
A conductive paste comprising high melting point metal particles, molten metal particles with a melting point of 700°C or lower, and active metal particles such as titanium hydride, which are baked at temperatures between 750-1000°C in a non-oxidizing atmosphere to form a strong bond with ceramic substrates without deforming fine patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If glass component-containing conductive paste is used for bonding to ceramic substrate, then ease of handling is improved, but bonding strength deteriorates
Solution Approach 1:
The conductive paste uses a composite material system combining Ag-Cu alloy particles (providing conductivity and melting behavior), TiH2 particles (providing active metal for strong bonding), and glass frit particles (providing ease of handling and bonding assistance). This composite approach allows the paste to exhibit multiple functions: the Ag-Cu alloy melts and flows for pattern formation, the TiH2 reacts with the ceramic substrate for strong chemical bonding, and the glass frit facilitates handling and bonding. The synergistic effect of these components resolves the contradiction between ease of handling and bonding strength.
2Reliability
If vacuum baking is used to achieve strong bonding and retain pattern shape, then bonding strength and pattern integrity are improved, but productivity deteriorates
Solution Approach 1:
The invention changes the baking parameters from vacuum conditions to nitrogen atmosphere conditions. This parameter change allows the use of conveyor-type baking furnaces which operate continuously in nitrogen atmosphere, dramatically improving productivity. The paste formulation (with TiH2 and controlled Ag-Cu alloy content) is specifically designed to achieve strong bonding and pattern retention under these new nitrogen atmosphere baking conditions (700-900°C), replacing the need for vacuum baking while maintaining or improving bonding strength and pattern integrity.
3Productivity
If Ag-Cu alloy paste is baked in nitrogen atmosphere to improve productivity, then productivity is improved, but pattern deformation occurs
Solution Approach 1:
The TiH2 particles act as an intermediary substance that prevents pattern deformation during nitrogen atmosphere baking. The titanium from TiH2 reacts with oxygen and other gases in the nitrogen atmosphere to form a protective layer, preventing excessive oxidation and contraction of the Ag-Cu alloy particles. This intermediary action allows the paste to be baked in nitrogen atmosphere (maintaining productivity) while preventing the pattern deformation that would otherwise occur.
4Strength
If active metal particles are added to conductive paste to improve bonding strength, then bonding strength is improved, but paste flow during baking increases making pattern formation difficult
Solution Approach 1:
The paste exhibits local quality differentiation where different components perform different functions at different stages. The TiH2 particles (active metal) are distributed throughout the paste to provide bonding strength, while the Ag-Cu alloy particles provide controlled melting and flowing behavior for pattern formation. The glass frit particles provide structural support and control the overall flow characteristics. This local quality differentiation allows the paste to simultaneously achieve strong bonding (from TiH2) and good pattern formation (from the balanced composition of all components with controlled flow properties).
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 achieves strong bonding of conductive parts to ceramic substrates even in nitrogen atmospheres, maintaining pattern shape integrity and improving productivity by preventing pattern contraction and deformation.
Implementation Method 1
a molten metal particle containing an alloy which melts at a temperature equivalent to or lower than a baking temperature and has a melting point of 700°C or lower
Implementation Method 2
an active metal particle containing an active metal... the active metal particle is at least one kind selected from the group consisting of a titanium hydride particle, a titanium boride particle and a zirconium hydride particle
Implementation Method 3
the baking temperature is equivalent to or higher than the sintering temperature of the high melting point metal particle
Data Source
AI summary
The present invention pertains to an electroconductive paste containing: high melting point metal particles having a melting point that exceeds the firing temperature; molten metal particles containing a metal or an alloy that melts at the firing temperature, for which the melting point is 700°C or less; active metal particles containing an active metal; and an organic vehicle.