Circuit Board Insulating Layers for Low Signal Loss
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Solution Overview
Problem
There is a demand for a circuit board with an insulating layer having a low dielectric constant and a circuit pattern with low signal loss, while maintaining adhesion between the insulating layer and the circuit pattern, and addressing chemical and mechanical properties such as isotropy, low reactivity, mechanical strength, and low thermal expansion.
Innovation Solution
The circuit board comprises multiple insulating portions with different materials, including a prepreg with glass fibers and resin coated copper (RCC) layers, where the RCC layers have a low dielectric constant and low coefficient of thermal expansion. A buffer layer is introduced between the insulating layer and the circuit pattern to improve adhesion, and the insulating layers are designed to have a single phase structure for enhanced mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface roughness of the circuit pattern is reduced to prevent conductor loss, then transmission loss is reduced, but the adhesion between the circuit pattern and the insulating layer is reduced
Solution Approach 1:
A buffer layer is introduced between the insulating layer and the circuit pattern to serve as an intermediary that enhances adhesion while allowing the circuit pattern surface roughness to be reduced for lower transmission loss. The buffer layer composition includes a resin component and a copper component, creating a transition zone that improves bonding between the smooth circuit pattern and the insulating layer.
2Loss of energy
If a material with low dielectric constant is used for the insulating layer to reduce dielectric loss, then transmission loss is reduced, but the mechanical strength and other chemical properties may be compromised
Solution Approach 1:
The insulating layer is constructed as a composite material combining resin and inorganic filler particles. This composite structure achieves low dielectric constant for reduced dielectric loss while maintaining adequate mechanical strength and other required properties through the synergistic combination of materials.
3Stability of the object's composition
If glass fiber is removed from the insulating layer to reduce thermal expansion, then coefficient of thermal expansion is reduced, but the mechanical strength may be reduced
Solution Approach 1:
The coefficient of thermal expansion of the insulating layer is controlled by adjusting the composition and content of inorganic filler particles. By carefully selecting filler types and concentrations, the thermal expansion parameter is optimized to match the copper circuit pattern, reducing delamination risk while maintaining mechanical integrity through the composite structure.
Data Source
AI summary
A circuit board according to an embodiment includes a first insulating portion including at least one insulating layer; a second insulating portion disposed on the first insulating portion and including at least one insulating layer; and a third insulating portion disposed under the first insulating portion and including at least one insulating layer; wherein the insulating layer constituting the first insulating portion includes a prepreg containing glass fibers, and wherein each of the insulating layers constituting the second and third insulating portions is made of resin coated copper (RCC).