Multilayer Ceramic Capacitor Firing Rate Control
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Solution Overview
Problem
The existing manufacturing process for multilayer ceramic capacitors faces issues with electrode peeling and electrode-end cracking due to stress generated between the multilayer body and outer electrodes, primarily caused by the differential shrinkage of Ni and the multilayer body during firing.
Innovation Solution
A method involving a controlled temperature increase from 800° C. to 1,100° C. at a rate of 15° C. per minute or more during firing, ensuring synchronized shrinkage of the conductive paste and the multilayer body, and using a conductive paste with a Ni primary component and a plating layer like Cu to reduce stress and prevent peeling and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conductive paste containing Ni and the multilayer body are fired at the same time, then the manufacturing process is simplified and productivity is improved, but stress is generated between the multilayer body and outer electrodes causing electrode peeling and electrode-end cracking
Solution Approach 1:
The patent applies parameter changes by carefully controlling the heating rate during the simultaneous firing process. Specifically, the heating rate is controlled to be 15°C/min or more in the temperature range of 800°C to 1100°C, which allows the Ni-based conductive paste and the multilayer body to shrink at synchronized rates, preventing stress accumulation while maintaining the benefits of simultaneous firing
Solution Approach 2:
The patent introduces dynamic control of the heating process by adjusting the heating rate based on the specific temperature range and material properties. The heating rate is dynamically increased in the critical range of 800°C to 1100°C where differential shrinkage occurs, allowing the system to adapt to changing material behavior during firing
2Productivity
If a high heating rate is used during firing, then the manufacturing time is reduced and productivity is improved, but thermal stress increases causing deformation and cracking
Solution Approach 1:
The patent optimizes the heating rate parameter to achieve a balance between productivity and structural integrity. By setting the heating rate to 15°C/min or more in the critical temperature range of 800°C to 1100°C, the patent enables sufficiently fast firing while preventing excessive thermal stress that would cause deformation or cracking
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 approach effectively reduces stress between the outer electrodes and the multilayer body, preventing electrode peeling and electrode-end cracking, thereby enhancing the reliability and integrity of the capacitors.
Implementation Method 1
the sintering temperature of Ni is 800° C. and the sintering temperature of the multilayer body is 1,100° C.
Implementation Method 2
shrinkage of Ni occurs prior to shrinkage of the multilayer body because the sintering temperature of Ni is 800° C. and the sintering temperature of the multilayer body is 1,100° C. Consequently, stress is generated between the multilayer body and the outer electrodes
Data Source
AI summary
A method for manufacturing a multilayer ceramic capacitor includes preparing a green multilayer body including a stack of dielectric sheets printed with inner electrodes, coating the green multilayer body with a conductive paste that is connected to the inner electrodes, and firing the conductive paste and the green multilayer body at the same time, wherein a rate of temperature increase from about 800° C. to about 1,100° C. during the firing is about 15° C. per minute or more.