Circuit Module Metal Layer Adhesion via Localized Surface Roughness
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Solution Overview
Problem
Conventional circuit modules face challenges in controlling the separation behavior of metal layers on side surfaces due to differences in thermal expansion coefficients between wiring structures and insulating resin layers, leading to compromised electromagnetic shielding and electrical characteristics during heat processing.
Innovation Solution
The circuit module design differentiates the surface roughness of side surfaces of the insulating resin layer and wiring structure, ensuring the metal layer adheres more strongly to the surface with higher roughness, allowing controlled separation behavior by prioritizing separation on the surface with lower roughness during heat processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal layer is provided on both the side surface of the wiring structure and the side surface of the insulating resin layer to ensure electromagnetic shielding, then the electromagnetic shielding effect is improved, but the separation of the metal layer occurs during heat processing due to CTE differences, deteriorating the shielding effect and electrical characteristics
Solution Approach 1:
The patent applies different surface roughness values to different side surfaces. Specifically, one side surface (where electromagnetic shielding is critical) is given a larger surface roughness to strengthen metal layer adherence and prevent separation, while other side surfaces have smaller roughness values. This local differentiation allows the metal layer to remain adhered where needed while still accommodating thermal expansion differences, thereby maintaining electromagnetic shielding effectiveness without suffering from separation issues.
2Reliability
If the metal layer is provided on the side surface of the wiring structure to shield the wiring, then the electromagnetic shielding for wiring is improved, but the metal layer separates during heat processing, markedly deteriorating the shielding effect
Solution Approach 1:
The patent implements different surface roughness values for different side surfaces of the wiring structure. The side surface requiring electromagnetic shielding is assigned a larger roughness value to ensure strong metal layer adherence and prevent separation during heat processing. This localized roughness control allows precise management of metal layer separation behavior, maintaining shielding effectiveness while controlling separation to acceptable levels.
3Reliability
If the metal layer is provided on the side surface of the insulating resin layer to shield the electronic component, then the electromagnetic shielding for electronic component is improved, but the metal layer separates during heat processing, markedly deteriorating the shielding effect
Solution Approach 1:
The patent applies a larger surface roughness value to the side surface of the insulating resin layer where electromagnetic shielding is critical. This enhanced roughness creates stronger mechanical interlocking between the metal layer and the insulating resin layer, preventing separation during heat processing. By locally increasing roughness only where shielding is needed, the patent maintains effective electromagnetic shielding for electronic components while controlling metal layer separation behavior.
4Strength
If the surface roughness is increased to improve metal layer adherence and prevent separation, then the adherence is improved, but the separation behavior becomes difficult to control uniformly across different side surfaces
Solution Approach 1:
The patent resolves the control complexity issue by implementing a differentiated roughness strategy: larger surface roughness is applied to side surfaces where electromagnetic shielding is critical and separation must be prevented, while smaller roughness values are used on other side surfaces. This local quality approach allows the patent to control separation behavior across different side surfaces in a systematic way, improving adherence where needed while maintaining overall device manageability and avoiding uniform high roughness that would complicate control.
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 approach enables precise control over metal layer separation, maintaining effective electromagnetic shielding and electrical characteristics by ensuring the metal layer on the surface with higher roughness remains adhered, thus improving the module's performance and reliability.
Implementation Method 1
the adherence between the side surface of the insulating resin layer and the metal layer is different from the adherence between the side surface of the wiring structure and the metal layer. The greater the surface roughness, the higher the adherence with respect to the metal layer.
Implementation Method 2
There is, however, a difference in CTE (coefficient of thermal expansion) between the wiring structure or the electronic component and the insulating resin layer, so that when heat processing is performed on the circuit module, stress is generated in the circuit module.
Data Source
AI summary
A circuit module 2 comprises: a wiring structure 4; an electronic component 6a, 6b arranged on the upper surface of the wiring structure 4; an insulating resin layer 8 which is provided on the upper surface of the wiring structure 4 and in which the electronic component 6a, 6b is embedded; and a metal layer 10 provided on a side surface S1 of the insulating resin layer 8 and a side surface S2 of the wiring structure 4. The surface roughness of the side surface S1 of the insulating resin layer 8 is expressed as R1. The surface roughness of the side surface S2 of the wiring structure 4 is expressed as R2. R1 and R2 differ from each other.