Circuit Module Electrode Plating Film Resin Interface
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Solution Overview
Problem
Circuit modules face issues with separation at the interface between external connection terminals and resin layers due to poor compatibility and thermal expansion differences, leading to reliability concerns when heated.
Innovation Solution
A circuit module design featuring a second electrode with a sintered metal column and a cylindrical second plating film that covers the electrode base body and metal column, providing improved compatibility and contact with the resin layer, along with a manufacturing method that includes polishing and etching steps to enhance the interface bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal pin or Cu paste is used to form the metal column, then the external connection terminal can be formed, but poor compatibility with the resin layer occurs due to high surface smoothness or poor wettability
Solution Approach 1:
A plating film is introduced as an intermediary layer between the metal column and the resin layer. This plating film serves as a mediator that improves interfacial compatibility and prevents separation caused by direct contact between the metal column (with poor surface properties) and the resin layer.
Solution Approach 2:
The external connection terminal is constructed as a composite structure consisting of multiple materials: the metal column (Cu or alloy), the plating film (different material properties), and the resin layer. This composite structure combines the advantages of each material to achieve both manufacturability and reliability.
2Ease of manufacture
If a metal pin or Cu paste is used to form the metal column, then the external connection terminal can be formed, but separation occurs at the interface between the metal column and resin layer when heated due to thermal expansion differences
Solution Approach 1:
The plating film acts as a buffer and intermediary layer that absorbs and distributes thermal stress. By having different thermal expansion properties than both the metal column and the resin layer, it prevents direct stress transmission that would cause interface separation during heating.
Solution Approach 2:
The invention changes the material parameters at the interface by introducing a plating film with specific thermal, mechanical, and surface properties. This parameter modification creates a gradient structure that accommodates thermal expansion differences and maintains interface stability under thermal stress.
3Ease of manufacture
If the external connection terminal structure is simplified, then manufacturing is easier, but connection reliability deteriorates due to insufficient stress alleviation
Solution Approach 1:
The external connection terminal is designed as a composite structure with multiple functional layers (metal column, plating film, resin layer integration). Each layer contributes specific properties: the metal column provides conductivity, the plating film provides interface compatibility and stress distribution, and the resin layer provides mechanical support and stress alleviation.
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 solution effectively suppresses separation at the interface between the external connection terminal and the resin layer, even under thermal stress, while reducing the module's height and improving handling by ensuring a flush surface, thus enhancing connection reliability and miniaturization.
Implementation Method 1
The metal column has one end directly connected to the second electrode base body and another end positioned in an inner side portion relative to the outer surface of the first resin layer, and is formed by metal powder being sintered
Data Source
AI summary
A circuit module includes a substrate on which a first electrode and a second electrode are provided, a first electronic component, and a first resin layer. The first electrode includes a first electrode base body and a first plating film. The second electrode and the first electronic component are covered with the first resin layer. The second electrode includes a second electrode base body, a metal column, whose one end is directly connected to the second electrode base body and another end is positioned in an inner side relative to an outer surface of the first resin layer, a second plating film with a cylindrical shape covering a side surface of a connection body of the second electrode base body and the metal column, and a covering portion connected to the other end of the metal column.