External Electrode Formation Method for Chip Components
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Solution Overview
Problem
The existing method of forming external electrodes on electronic components by rubbing conductive paste onto the end face of a chip results in unstable electrode shapes on side faces, making it difficult to control electrode length and width, leading to potential short circuits and the Manhattan phenomenon during chip mounting.
Innovation Solution
A method involving pre-formation of a conductive paste precoat on the end face, followed by application and drying of the paste from opposite directions on the side faces to form stable electrode portions, ensuring sufficient thickness and preventing spreading, allowing for precise control of electrode dimensions and pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the amount of conductive paste is increased to extend the external electrode length away from the ridgeline, then the electrode length increases, but the electrode width along the ridgeline also increases, reducing the distance between adjacent electrodes and causing short circuits
Solution Approach 1:
A precoat portion is formed on the end face before applying conductive paste to the side faces. This preliminary layer serves as a barrier that prevents the paste from spreading excessively along the ridgeline, allowing the electrode to extend adequately away from the ridgeline while maintaining controlled width and proper spacing between adjacent electrodes.
2Manufacturing precision
If the amount of conductive paste is decreased to maintain distance between adjacent electrodes, then the electrode width is controlled, but the electrode length away from the ridgeline is reduced, failing to assure sufficient electrode area
Solution Approach 1:
The precoat portion is applied in advance on the end face to create a controlled foundation. This allows subsequent paste application to achieve sufficient electrode area extending away from the ridgeline while the precoat acts as a barrier to prevent excessive width expansion along the ridgeline, thus maintaining proper spacing between electrodes.
Solution Approach 2:
The electrode formation process is divided into distinct stages: forming the precoat portion on the end face, then applying paste to form electrode portions on side faces. This segmentation allows independent control of electrode dimensions - the precoat controls width while the subsequent paste application determines length, achieving both sufficient area and proper spacing.
3Productivity
If the conductive paste is applied and dried in a single step, then the process is simple, but the electrode shape is unstable and may cause the Manhattan phenomenon during chip mounting
Solution Approach 1:
The electrode formation process is segmented into multiple steps: forming a precoat portion on the end face, then applying and drying paste on side faces to form electrode portions. This segmentation provides intermediate control points that stabilize the electrode shape at each stage, preventing the Manhattan phenomenon while maintaining practical production efficiency.
Solution Approach 2:
The precoat portion is formed in advance before applying paste to the side faces. This preliminary action creates a stable foundation that controls the initial shape and prevents excessive spreading, ensuring electrode shape stability throughout the subsequent drying and formation processes.
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 method enables the stable formation of external electrodes with controlled lengths and widths, preventing short circuits and ensuring adequate electrode area, even at narrow pitches, thereby enhancing the reliability of electronic component assembly.
Implementation Method 1
a pre-formation step of applying a conductive paste onto the third face, and evaporating at least a part of a liquid contained in the applied conductive paste
Implementation Method 2
an electrode formation step of drying the element to form the external electrode consisting of the first electrode portion, the second electrode portion, and the third electrode portion
Data Source
AI summary
An element forming an electronic component has a first face and a second face facing each other, and a third face adjacent to each of the first face and the second face. A method of forming an external electrode of the electronic component involves a pre-formation step, first to third formation steps, and an electrode formation step. The pre-formation step is to apply a conductive paste onto the third face and to evaporate at least a part of a liquid contained in the applied conductive paste, to form a precoat portion expected to become a part of a third electrode portion. The first formation step is to apply the conductive paste from a direction opposite to the first face, onto the first face to form a first electrode portion. The second formation step is to apply the conductive paste from a direction opposite to the second face, onto the second face to form a second electrode portion. The third formation step is to apply the conductive paste onto the third face so as to cover the precoat portion, to form the third electrode portion. The electrode formation step is to dry the element to form the external electrode consisting of the first electrode portion, the second electrode portion, and the third electrode portion. The first electrode portion, the second electrode portion, and the third electrode portion are formed so as to connect with each other.