Multilayer Ceramic Capacitor Electrode Insulation for Tombstone Prevention
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face issues with mechanical strength and stability during mounting on a substrate, particularly due to the tombstone phenomenon caused by the formation of an electrically insulating layer that affects the wettability with solder, leading to potential cracks and instability.
Innovation Solution
A multilayer ceramic electronic component design featuring a multilayer body with inner and outer electrodes, where an insulating layer continuously covers the end edge portions of the outer electrodes, ensuring that the dimension of the insulating layer exceeds that of the plating layer, thereby reducing stress concentrations and preventing cracks, and allowing stable mounting on a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrically insulating layer is formed on the bottom surface portion after terminal electrode formation to prevent cracks, then crack resistance is improved, but the distance between conductor surface and solder increases causing tombstone phenomenon
Solution Approach 1:
The insulating layer is segmented into two distinct parts: a first insulating layer formed on the bottom surface portion with thickness t1, and a second insulating layer formed on the side surface portion with thickness t2. This segmentation allows each layer to serve different functions - the first layer provides crack resistance while the second layer maintains proper solder contact distance, thereby resolving the contradiction between crack prevention and mounting precision.
Solution Approach 2:
Different thicknesses are applied to different locations of the insulating layer. The first insulating layer has thickness t1 at the bottom surface where crack resistance is needed, while the second insulating layer has greater thickness t2 at the side surface where preventing tombstone phenomenon is critical. This local differentiation of quality allows simultaneous achievement of both crack resistance and mounting precision.
2Strength
If the insulating layer thickness is increased to improve mechanical strength, then stress resistance is improved, but the distance to solder increases worsening mounting stability
Solution Approach 1:
The insulating layer is divided into two segments with different thicknesses: the first insulating layer provides baseline mechanical strength protection, while the second insulating layer extends further at the side surface to maintain optimal solder contact distance. This segmentation enables the structure to achieve both enhanced mechanical strength and mounting stability simultaneously.
Solution Approach 2:
The insulating layer configuration transitions from a single-dimensional thickness increase to a two-dimensional differentiated structure. By extending the insulating layer differently in the vertical direction (first layer) versus the horizontal direction (second layer), the design achieves mechanical strength enhancement without compromising mounting stability, as the side surface extension prevents excessive solder distance while the bottom surface layer provides stress protection.
Data Source
AI summary
A multilayer ceramic electronic component includes a multilayer body including layered ceramic layers and layered inner electrode layers and having a rectangular parallelepiped shape, and outer electrodes covering both end surfaces of the multilayer body and extending from both end surfaces to cover at least a portion of a first main surface of the multilayer body. The multilayer ceramic capacitor includes an insulating layer continuously extending from a ceramic layer at the first main surface of the multilayer body so as to cover end edge portions of both the outer electrodes located on the first main surface of the multilayer body, and t2>t1 is satisfied.