Circuit Board Coating Layer for Signal Loss and Adhesion
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Solution Overview
Problem
Circuit boards for high-frequency applications face challenges in minimizing signal transmission loss while maintaining adhesion between the insulating layer and circuit pattern, and in reducing the overall thickness without compromising reliability, due to surface roughness and dielectric constant issues.
Innovation Solution
A circuit board design incorporating a coating layer with specific functional groups that enhance adhesion between the insulating layer and the circuit pattern layer, using a combination of hydrogen bonding and coordination with metal layers, along with optimized thickness and surface roughness values for the metal layers to improve plating uniformity and reduce signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface roughness of the circuit pattern is reduced, then transmission loss is prevented, but adhesion between the circuit pattern and the insulating layer is reduced
Solution Approach 1:
A coating layer comprising a silane compound is introduced as an intermediary between the insulating layer and the circuit pattern layer. This coating layer has dual functionality: it bonds to the insulating layer through silane bonding and provides sufficient surface roughness for copper foil adhesion, thereby resolving the contradiction between minimizing transmission loss and maintaining adhesion.
2Length of stationary object
If an insulating layer with low dielectric constant is used, then the overall thickness of the circuit board can be reduced, but reliability issues such as warping, cracking, and delamination occur
Solution Approach 1:
The patent changes the chemical composition parameters of the insulating layer by incorporating specific materials (polyimide, epoxy resin, phenolic resin, polyamide, or polyethylene naphthalate) with controlled dielectric constants and thermal expansion coefficients. This allows achieving both thin profile and reliability by optimizing material parameters rather than simply reducing thickness.
Solution Approach 2:
The insulating layer is designed as a composite material system combining multiple polymers and the silane-based coating layer. This composite structure provides both the low dielectric constant needed for thin design and the mechanical strength needed to prevent warping, cracking, and delamination.
3Manufacturing precision
If the insulating layer is made thinner to slim the circuit board, then fine circuit patterns can be implemented, but reliability problems such as warping, cracking, and peeling become more severe
Solution Approach 1:
The silane compound coating layer serves as a mediator that enables fine circuit patterns on thin insulating layers by providing the necessary adhesion interface. The coating layer compensates for the reduced mechanical support of thinner insulating layers, allowing fine patterns without reliability degradation.
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 improves adhesion and reliability, allowing for finer circuit patterns and reduced board thickness, enhancing signal integrity and integration density while minimizing signal transmission loss.
Implementation Method 1
the first functional group of the coating layer is hydrogen bonded with the first insulating layer
Implementation Method 2
the second functional group of the coating layer is coordinated with the first metal layer
Data Source
AI summary
A circuit board according to an embodiment includes a first insulating layer, a coating layer disposed on the first insulating layer, and a circuit pattern layer disposed on the coating layer, wherein the circuit pattern layer includes a first metal layer disposed on the coating layer, and a second metal layer disposed on the first metal layer, wherein the coating layer includes a first functional group bonded to the first insulating layer, and a second functional group bonded to the first metal layer.