Insulating Film Surface Bonding Layer for PCB Adhesion
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Solution Overview
Problem
The challenge is to enhance the bonding force between an insulating layer and a metal layer in printed circuit boards without increasing surface roughness, which is crucial for reducing radio-frequency signal loss, especially in 5G wireless communications where materials like liquid crystal polymer (LCP) exhibit low bonding force due to high hydrophobicity and low surface roughness.
Innovation Solution
An insulating film with a surface bonding layer containing a radical generation element and a coordinate bond element, where the atom content ratio of these elements is between 0.05 and 0.35, is used to improve bonding force. This surface bonding layer forms covalent and coordinate bonds with the insulating and metal layers, respectively, using UV-O3 treatment and a linker to generate radicals and coordinate bonds, thereby enhancing adhesion without increasing surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mechanical surface treatment method is used to improve bonding force between insulating layer and metal layer, then bonding force is improved, but surface roughness increases causing radio-frequency signal loss
Solution Approach 1:
The invention changes the chemical composition parameters of the insulating layer by incorporating specific elements (Al, Si, Ti, Fe, Mn, Zn, B, or F) at controlled concentrations (0.1-5.0 at%). This chemical parameter modification enables improved bonding force through chemical affinity with metal layers while maintaining surface smoothness to prevent radio-frequency signal loss, avoiding the need for mechanical surface roughening.
2Reliability
If liquid crystal polymer is used as insulating material, then dissipation factor is reduced and high-speed data transmission is achieved, but bonding force is reduced due to high hydrophobicity and low surface roughness
Solution Approach 1:
The invention applies local quality modification by introducing specific bonding-enhancing elements (Al, Si, Ti, Fe, Mn, Zn, B, or F) at controlled concentrations (0.1-5.0 at%) within the liquid crystal polymer matrix. This creates localized regions with enhanced chemical reactivity and bonding affinity while preserving the bulk material's low dissipation factor and hydrophobic characteristics, thus improving bonding force without compromising the insulating material's electrical performance.
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 approach significantly improves the bonding force between the insulating film and the metal layer, reducing radio-frequency signal loss while maintaining low surface roughness, thus addressing the limitations of existing technologies with liquid crystal polymer-based insulating materials.
Implementation Method 1
UV-O3 treatment and a linker to generate radicals and coordinate bonds
Implementation Method 2
a coordinate bond element, wherein in the surface bonding layer, a/b is 0.05 or more and 0.35 or less, in which 'a' is an atom content of the coordinate bond element and 'b' is an atom content of the radical generation element
Data Source
AI summary
An insulating film includes an insulating layer and a surface bonding layer disposed on the insulating layer. The surface bonding layer includes a radical generation element and a coordinate bond element. In the surface bonding layer, a/b is 0.05 or more and 0.35 or less, in which ‘a’ is an atom content of the coordinate bond element and ‘b’ is an atom content of the radical generation element.