Ceramic Substrate Projecting Electrodes Sintering Control
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Solution Overview
Problem
The existing methods for forming projecting electrodes in ceramic substrates face challenges in achieving low specific resistance while preventing structural defects such as cracks, as increasing the amount of alumina or other materials to control contraction leads to higher specific resistance, and reducing their amount results in uncontrolled contraction and defects.
Innovation Solution
A method involving the use of ceramic green sheets and electrode formation sheets with a first electrically conductive paste containing a conductive metal and anti-sintering ceramic, where the anti-sintering ceramic controls the sintering of the conductive metal, forming projecting electrodes with a porous structure through necking between particles, and optionally using constraining or resin sheets that burn away during firing to manage contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alumina or other materials are added to control contraction upon sintering, then structural defects such as cracks are prevented, but the specific resistance of the projecting electrodes increases
Solution Approach 1:
The invention changes the particle size distribution parameter of the electrically conductive powder, specifically using a bimodal distribution with fine particles (0.5-5 μm) and coarse particles (5-20 μm). This parameter change allows the paste to form dense, crack-free projecting electrodes with low specific resistance without requiring additional alumina or other contraction-controlling materials
Solution Approach 2:
The invention uses a composite paste composition combining electrically conductive metal powder with specific particle size distribution, organic vehicle, and optional glass powder. This composite structure enables the paste to self-control its sintering behavior and contraction, eliminating the need for separate alumina additives while maintaining both structural integrity and low electrical resistance
2Quantity of substance
If alumina or other materials are reduced to lower specific resistance, then electrical conductivity improves, but contraction upon sintering is not controlled resulting in structural defects
Solution Approach 1:
The invention changes the particle size distribution parameter of the electrically conductive powder, specifically using a bimodal distribution with fine particles (0.5-5 μm) and coarse particles (5-20 μm). This parameter change allows the paste to form dense, crack-free projecting electrodes with low specific resistance without requiring additional alumina or other contraction-controlling materials
Solution Approach 2:
The organic vehicle in the paste acts as an intermediary that facilitates proper particle arrangement and bonding during sintering. The specific composition (including ethyl cellulose, terpineol, and water) mediates the sintering process to achieve dense packing and strong bonding without requiring alumina additives, thus preventing cracks while maintaining low resistance
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 ceramic substrates with projecting electrodes that are free from cracks and have low specific resistance, maintaining structural integrity and electrical conductivity.
Implementation Method 1
a step of firing the composite multilayer body at a temperature at which the ceramic green sheets sinter. The first electrically conductive powder contains at least one electrically conductive metal and at least one anti-sintering ceramic that controls the sintering of particles of the electrically conductive metal
Implementation Method 2
the electrode formation sheets are resin sheets that burn away at or below the temperatures at which the ceramic green sheets sinter. In this case, the resin sheets are burnt away in the step of firing the composite multilayer body
Data Source
AI summary
A method for producing a ceramic substrate that includes a substrate body having ceramic layers and columnar projecting electrodes on a first primary surface of the substrate body. The method includes a step of preparing electrode formation sheets for forming the projecting electrodes, a step of perforating the electrode formation sheets with through holes and filling the through holes with a first electrically conductive paste containing a first electrically conductive powder, a step of building a composite multilayer body by stacking ceramic green sheets and the electrode formation sheets on a first primary surface of the stack of ceramic green sheets. The first electrically conductive powder contains electrically conductive metal(s) and anti-sintering ceramic(s) that controls the sintering of particles of the electrically conductive metal(s), with at least part of the surface of the particles of the electrically conductive metal(s) covered with the anti-sintering ceramic(s).