Circuit Board Resin Layer High-Frequency Signal Transmission
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Solution Overview
Problem
High-frequency signal transmission losses and crosstalk issues in printed wiring boards due to the adhesive layer impairing dielectric loss characteristics and smoothness, particularly in flexible printed circuit boards and flexible flat cables.
Innovation Solution
A circuit board design with a resin layer and metal layer laminated in contact, where the resin layer has a relative permittivity of 2 to 3 and a dielectric loss tangent of 0.001 to 0.01 at 10 GHz, and a peel strength of 5 N/cm or greater, ensuring excellent smoothness and reduced transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer is used to laminate the resin layer and metal layer in FPC and FFC, then the layers can be bonded together, but the adhesive layer impairs the low dielectric loss characteristics and smoothness of the mounting substrate
Solution Approach 1:
The invention extracts and removes the adhesive layer from the laminate structure. By directly laminating the resin layer and metal layer without an adhesive layer in between, the source of dielectric loss and surface irregularity is eliminated, while the layers are still bonded together through direct contact and lamination pressure.
Solution Approach 2:
The invention merges the resin layer and metal layer into a single integrated laminate structure without an intermediate adhesive layer. The two layers are directly bonded through lamination, combining their functions while eliminating the harmful effects of the adhesive layer on dielectric properties and surface smoothness.
2Strength
If an adhesive layer is used to laminate the resin layer and metal layer, then the layers can be bonded together, but the adhesive layer reduces the smoothness of the mounting substrate
Solution Approach 1:
The adhesive layer is extracted and removed from the laminate structure. By eliminating this intermediate layer, the direct contact between the resin layer and metal layer creates a smoother interface, removing the source of surface irregularity that the adhesive layer would introduce.
Solution Approach 2:
The resin layer and metal layer are merged into a single integrated structure through direct lamination without an adhesive intermediary. This direct bonding approach eliminates the surface irregularities that would be introduced by an adhesive layer, resulting in a smoother overall substrate surface.
3Ease of manufacture
If conventional materials are used in printed wiring boards, then manufacturing is easier, but transmission loss increases at high frequencies
Solution Approach 1:
The invention changes the dielectric parameters of the resin layer by selecting materials with specific properties (dielectric constant of 2.0-3.0 and dielectric loss tangent of 0.001-0.01 at 10 GHz). This parameter optimization reduces transmission loss at high frequencies while maintaining manufacturability through standard lamination processes.
Solution Approach 2:
The invention uses a composite structure consisting of a resin layer and metal layer directly laminated together. This composite material approach allows optimization of dielectric properties for high-frequency performance while eliminating the adhesive layer that would otherwise increase transmission loss.
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 solution provides a circuit board with improved high-frequency signal transmission characteristics, reduced transmission loss, and enhanced smoothness, enabling better integration of layers and positioning accuracy.
Implementation Method 1
the resin layer at a frequency 10 GHz having a relative permittivity of from 2 to 3
Implementation Method 2
a dielectric loss tangent of the resin layer may be from 0.001 to 0.01 at a frequency of 10 GHz
Data Source
AI summary
The circuit board according to the present invention includes a wiring portion and a non-wiring portion, the wiring portion having a metal layer and a resin layer, the non-wiring portion having a resin layer, the resin layer at a frequency 10 GHZ having a relative permittivity of from 2 to 3 at 23° C., and the circuit hoard satisfying a relationship: (A−B)/B≤0.1 wherein A is the maximum value of the thickness in the wiring portion (μm) and B is the minimum value of the thickness in the non-wiring portion (μm).