Circuit Module Shield Layer Adhesion Under Thermal Stress
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Solution Overview
Problem
Conventional circuit modules experience stress and separation issues between the metal layer and insulating resin layer due to differences in thermal expansion coefficients, leading to compromised electromagnetic shielding and electrical characteristics, especially when heat processing is applied.
Innovation Solution
The circuit module design features a metal layer with higher adherence directly above electronic components by varying the surface roughness of the insulating resin layer, ensuring that the metal layer is harder to separate from the resin layer, with R1/R2 ranging from 1.01 to 8.00, thereby mitigating stress and maintaining electromagnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat processing is performed on the circuit module, then the electronic component is cured or bonded, but stress is generated due to CTE difference between the electronic component and the insulating resin layer
Solution Approach 1:
The patent applies different surface roughness values to different regions of the insulating resin layer. The region directly above the electronic component has a first surface roughness value, while other regions have a second surface roughness value. This local differentiation allows the metal layer to have varying adherence strengths in different areas, enabling stress management during heat processing while maintaining reliable bonding where needed.
2Reliability
If the metal layer is provided on the insulating resin layer for electromagnetic shielding, then the electronic component is protected from electromagnetic interference, but the metal layer is likely to separate from the insulating resin layer when stress is applied
Solution Approach 1:
The patent creates regions with different surface roughness values on the insulating resin layer to achieve varying metal layer adherence. The region directly above the electronic component has higher adherence (first surface roughness value) to maintain electromagnetic shielding, while other regions have lower adherence (second surface roughness value) to allow stress relief and prevent separation.
Solution Approach 2:
The patent changes the surface roughness parameter of the insulating resin layer to control metal layer adherence. By adjusting the surface roughness values in different regions, the patent optimizes the balance between maintaining electromagnetic shielding effectiveness and preventing metal layer separation under stress.
3Ease of operation
If the metal layer is utilized as a wiring layer, then electrical connections are provided, but the stray capacitance between the electronic component and the metal layer changes, causing electrical characteristics to deviate from design intention
Solution Approach 1:
The patent applies different surface roughness values to different regions of the insulating resin layer. The region directly above the electronic component has a first surface roughness value that maintains consistent stray capacitance for reliable electrical characteristics, while other regions have a second surface roughness value that reduces stress and prevents metal layer separation.
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 design effectively prevents the metal layer from separating from the insulating resin layer directly above electronic components, even under thermal stress, thus maintaining the electromagnetic shielding effect and electrical characteristics of the circuit module.
Implementation Method 1
the adherence between the insulating resin layer and the metal layer on the portion directly above the electronic component is higher than the adherence between the insulating resin layer and the metal layer on the portion other than the portion directly above the electronic component
Implementation Method 2
There is a difference in CTE (coefficient of thermal expansion) between 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; at least one 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 at least one electronic component 6a, 6b is embedded; and a metal layer 10 provided on the upper surface of the insulating resin layer 8. The surface roughness of the portion S1 directly above each electronic component on the upper surface of the insulating resin layer 8 is expressed as R1. The surface roughness of the portion S2 other than the portion directly above all the electronic components on the upper surface of the insulating resin layer 8 is expressed as R2. At least one R1 satisfies the condition: R1>R2.