Circuit Substrate Asymmetric Metal Block Roughness
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Solution Overview
Problem
Existing circuit substrates face issues with peeling of insulating resin layers from metal blocks, which reduces the fixing strength and efficiency of heat dissipation, due to thermal expansion and contraction differences between the metal block and the resin layers.
Innovation Solution
A circuit substrate design featuring a core substrate with a penetrating cavity, a metal block with roughened surfaces of different roughness, and build-up layers on both sides with insulating resin layers that cover the metal block, increasing the contact area and stability, and an electronic component mounting structure on one side for efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If insulating resin layers are applied on metal block surfaces with uniform roughness, then the manufacturing process is simple, but peeling occurs due to thermal expansion differences reducing fixation strength
Solution Approach 1:
The patent applies different surface roughness to different regions of the metal block. Specifically, the first surface has a first roughness and the second surface has a second roughness that is greater than the first roughness. This local differentiation allows each surface to be optimized for its specific function while maintaining overall manufacturing feasibility.
Solution Approach 2:
The patent introduces asymmetry in the surface roughness of the metal block. Instead of uniform roughness, the second surface is deliberately made rougher than the first surface. This asymmetric design creates different bonding characteristics on each surface, preventing peeling by accommodating thermal expansion differences through enhanced mechanical interlocking on the rougher surface.
2Strength
If metal block surfaces are roughened to increase contact area, then fixation strength improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies surface roughening selectively to specific surfaces of the metal block rather than uniformly to all surfaces. The second surface is roughened to a greater degree than the first surface, optimizing the contact area and fixation strength only where needed while minimizing overall manufacturing complexity.
3Temperature
If insulating resin layers fully cover metal block surfaces, then heat dissipation efficiency improves, but peeling occurs due to thermal stress
Solution Approach 1:
The patent uses asymmetric surface roughness to differentiate the bonding characteristics on each surface of the metal block. The second surface has greater roughness than the first surface, creating stronger mechanical interlocking that compensates for thermal stress during heat dissipation operations, thereby preventing peeling while maintaining effective thermal contact.
Solution Approach 2:
The patent changes the surface roughness parameter of the metal block to optimize both heat dissipation and adhesion. By controlling the roughness values (first roughness and second roughness where second > first), the patent achieves a balance between thermal contact efficiency and resistance to peeling under thermal stress.
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 design effectively suppresses peeling of insulating resin layers from the metal block, enhances the fixing strength, and improves heat dissipation efficiency by increasing the contact area between the metal block and the resin layers, while preventing short circuits through controlled surface processing.
Implementation Method 1
the first and second surfaces of the metal block have roughened surfaces, respectively, and that the roughened surface of the first surface has a surface roughness which is different from a surface roughness of the roughened surface of the second surface
Implementation Method 2
a first build-up layer laminated on a first side of the core substrate and including insulating resin layers such that the first build-up layer is covering a first surface of the metal block
Implementation Method 3
enhances heat dissipation efficiency by utilizing the differing surface roughness and groove-shaped side surfaces of the metal block
Data Source
AI summary
A circuit substrate includes a core substrate having a cavity penetrating through the substrate, a metal block accommodated in the cavity of the substrate, a first build-up layer laminated on first side of the substrate and including insulating resin layers such that the first build-up layer is covering first surface of the block from the first side, and a second build-up layer laminated on second side of the substrate and including insulating resin layers such that the second build-up layer is covering second surface of the block from the second side. The first build-up layer includes an electronic component mounting structure formed on outermost portion of the first build-up layer, and the block is formed such that the first and second surfaces have roughened surfaces, respectively, and that the roughened surface of the first surface has surface roughness different from surface roughness of the roughened surface of the second surface.