Circuit Board Coating Layer for Low-Loss Signal and Adhesion
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Solution Overview
Problem
Circuit boards for high-frequency applications face challenges in minimizing signal transmission loss and maintaining adhesion between the insulating layer and the circuit pattern layer, while also addressing reliability issues such as warping, cracking, and delamination due to the use of low dielectric constant materials.
Innovation Solution
A circuit board design that includes a coating layer between the insulating layer and the circuit pattern layer, featuring a first metal layer with a thickness of 1-2.5 um and a coating layer with specific functional groups that enhance adhesion, regardless of the resin type, achieved by surface treating the insulating layer with corona or UV to generate reactive groups for chemical bonding.
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 contains reactive groups that chemically bond with both the insulating layer and the metal layer, serving as a mediator that maintains adhesion even when surface roughness is reduced for lower transmission loss
Solution Approach 2:
The invention changes the chemical parameters of the interface by applying a coating layer with specific chemical composition (silane compound with reactive groups). This chemical modification enables the interface to maintain strong adhesion through chemical bonding rather than relying solely on physical mechanical interlocking, allowing surface roughness to be optimized for electrical performance
2Volume of moving object
If an insulating layer with low dielectric constant is used, then circuit board thickness is reduced, but reliability issues such as warping, cracking, and delamination occur
Solution Approach 1:
The coating layer acts as an intermediary that chemically bonds to both the low dielectric constant insulating layer and the circuit pattern layer, providing strong interfacial adhesion that prevents delamination and structural failures even when using thin insulating layers with low dielectric constants
Solution Approach 2:
The invention creates a composite structure by introducing a coating layer with specific chemical properties (silane compound) between the insulating layer and circuit pattern layer. This composite approach combines the low dielectric constant property of the insulating layer with the strong adhesion capability of the coating layer, achieving both thickness reduction and structural integrity
3Volume of moving object
If the thickness of the insulating layer is reduced, then circuit board is slimmed, but warping and cracking occur
Solution Approach 1:
The coating layer serves as a mediator that provides strong chemical bonding between the thin insulating layer and the circuit pattern layer, distributing mechanical stresses and preventing warping and cracking that would otherwise occur in thin insulating layer structures
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 between the insulating layer and the circuit pattern layer, reduces signal transmission loss, and enhances the reliability of the circuit board by refining line widths and increasing circuit integration, while being applicable to all types of resin insulating layers.
Implementation Method 1
the insulating layer includes a reactive group bonded to the first functional group
Implementation Method 2
achieved by surface treating the insulating layer with corona or UV to generate reactive groups for chemical bonding
Implementation Method 3
Components mounted on the printed circuit board may transmit a signal generated from the component by a circuit pattern connected to each component
Implementation Method 4
The conductor loss due to the metal thin film is related to a surface roughness of the circuit pattern. That is, as the surface roughness of the circuit pattern increases, transmission loss may increase due to a skin effect
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, the coating layer includes a first functional group, and the first insulating layer includes a reactive group bonded to the first functional group.