Multilayer Ceramic Capacitor Base Electrode Crack Water Repellent
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Solution Overview
Problem
Reducing the thickness of the base external electrode layer in multilayer ceramic capacitors to increase capacity without increasing size compromises moisture-resistant reliability due to potential hydrogen penetration through the plating solution and glass pores.
Innovation Solution
Forming cracks in the glass of the base external electrode layer before applying a water repellent to ensure the repellent adheres to internal surfaces, preventing new crack formation and hydrogen penetration, thus maintaining reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the thickness of the base external electrode layer is reduced to increase capacitor capacity without increasing size, then the volume available for dielectric layers increases and capacity improves, but moisture-resistant reliability decreases due to potential hydrogen penetration through plating solution into pores or glass of the thinned base external electrode layer
Solution Approach 1:
The patent applies water repellent to the base external electrode layer before forming the plating layer. This preliminary action prevents the plating solution from penetrating into pores or glass of the base external electrode layer during subsequent plating processes, thereby preventing hydrogen penetration that would cause insulation degradation. This allows the base external electrode layer to be made thinner while maintaining moisture-resistant reliability.
Solution Approach 2:
The water repellent acts as an intermediary substance between the base external electrode layer and the plating solution. It forms a protective barrier that prevents direct contact between the plating solution and the porous structure of the base external electrode layer, thereby blocking the pathway for hydrogen penetration while allowing the base external electrode layer to maintain its thinned structure for increased capacitor capacity.
2Reliability
If water repellent is applied to the base external electrode layer to prevent hydrogen penetration, then moisture-resistant reliability improves, but subsequent rinsing to increase hydrophilic properties may cause cracks in the glass of the base external electrode layer, allowing plating solution penetration and hydrogen ingress
Solution Approach 1:
The patent performs rinsing to increase hydrophilic properties before applying the water repellent, not after. This preliminary rinsing occurs when the glass is still intact and not under the stress of subsequent drying processes that would cause cracking. The water repellent is then applied to the already-rinsed surface, and the hydrophilic properties are maintained without causing glass cracks, thus preserving both moisture-resistant reliability and structural integrity.
Solution Approach 2:
The patent inverts the conventional sequence of operations by performing the rinsing to increase hydrophilic properties before applying the water repellent, rather than after. This reversal prevents the sequence-induced glass cracking problem while maintaining the desired hydrophilic surface properties for subsequent plating adhesion.
3Volume of stationary object
If the base external electrode layer is made thinner to increase capacitor capacity, then more volume is available for dielectric layers and internal electrodes, but the ability to prevent penetration of plating solution into pores and glass is compromised
Solution Approach 1:
The water repellent serves as an intermediary protective layer on the base external electrode layer. It prevents the plating solution from penetrating into the pores and glass structure of the thinned base external electrode layer, thereby blocking the harmful effect of plating solution penetration while allowing the base external electrode layer to maintain its reduced thickness for increased capacitor capacity.
Solution Approach 2:
The water repellent is applied to the base external electrode layer before the plating process. This preliminary protective coating prevents plating solution penetration during the subsequent plating operations, enabling the use of a thinner base external electrode layer without compromising protection against harmful plating solution ingress.
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 allows for a thinner base external electrode layer while maintaining high moisture-resistant reliability and preventing insulation degradation, enabling the production of high-capacity multilayer ceramic capacitors with reduced external electrode thickness.
Implementation Method 1
cracks formed in advance cause the water repellent to adhere also to the internal surfaces of the cracks through application of the water repellent
Implementation Method 2
applying a conductive paste including metal powder and glass frit to an outer surface of the ceramic body and baking the conductive paste to form a base external electrode layer
Data Source
AI summary
A method includes producing a ceramic body including a stack of a dielectric layer and an internal electrode, applying a conductive paste including metal powder and glass frit to an outer surface of the ceramic body and baking the conductive paste to form a base external electrode layer, forming a crack in glass exposed to an outer surface of the base external electrode layer, after the formation of the crack, applying a water repellent to the base external electrode layer, and forming a Ni plating layer and a Sn plating layer on the base external electrode layer.