Ceramic Copper Circuit Board Roughness Control for Ag Bonding
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Solution Overview
Problem
The bonding strength between a silver (Ag) layer and a copper member on a ceramic copper circuit board is reduced due to the average length RSm of the roughness curve elements on the copper member's surface.
Innovation Solution
A ceramic copper circuit board is designed with a copper member bonded to a ceramic substrate, where the average value of five average lengths RSm of roughness curve elements on the copper member's surface is controlled to be between 40 µm and 250 µm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the copper member surface is made smooth, then the manufacturing process is simpler, but the bonding strength with silver layer is reduced
Solution Approach 1:
The invention changes the surface roughness parameters of the copper member by controlling the average length of roughness curve elements (RSm) to be 40-250 μm. This parameter optimization creates an anchor effect that mechanically interlocks with the silver paste, significantly improving bonding strength while maintaining a relatively simple manufacturing process through controlled surface treatment.
2Strength
If the surface roughness is increased to improve bonding, then the bonding strength increases, but the surface becomes more complex to manufacture
Solution Approach 1:
Instead of creating extreme surface roughness, the invention optimizes the RSm parameter to a specific range (40-250 μm). This moderate roughness level provides sufficient anchor effect for bonding while avoiding excessive manufacturing complexity. The controlled roughness can be achieved through standard surface treatment processes.
3Ease of manufacture
If the RSm value is decreased for smoother surface, then the manufacturing is easier, but the anchor effect for bonding layer is reduced
Solution Approach 1:
The invention establishes a minimum RSm threshold of 40 μm to ensure adequate anchor effect for reliable bonding. This parameter boundary ensures that the surface roughness is sufficient to mechanically interlock with the silver paste while still being achievable through practical manufacturing processes, thus maintaining bonding reliability.
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 control of surface roughness enhances the anchor effect for the bonding layer, resulting in increased bonding strength between the copper member and the silver layer, thereby improving the reliability of the ceramic copper circuit board.
Implementation Method 1
the average length RSm of the roughness curve elements of the surface of the copper member is controlled... enhances the anchor effect for the bonding layer, resulting in increased bonding strength
Data Source
Figure 1~2
Figure 3
AI summary
Provided are: a ceramic copper circuit board in which the average length RSm of the roughness curve element on the surface of a copper member is controlled; and a semiconductor device using same. A ceramic copper circuit to one surface of the ceramic substrate. When the average length RSm of the roughness curve element is measured at each of five arbitrary points selected from the surface of the copper member, the average value of the five average lengths RSm is 40-250µm