Copper Clad Laminate Structure for Low-Dk High-Heat PCB Substrates
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Solution Overview
Problem
There is a need for copper clad laminates (CCL) with improved electrical and mechanical properties, particularly for high-frequency and heat-resistant circuit boards that require low dielectric constants (Dk), minimal dissipation factors (Df), low coefficients of thermal expansion (CTE), strong adhesion to various substrates, and low water absorption.
Innovation Solution
A laminate structure comprising a first metal foil, a first insulating layer with a diisoalkenylarene and divinylarene copolymer, and a second insulating layer with glass fiber and another dielectric polymer, optimized for specific thickness and composition to achieve low Dk and Df, with optional additional layers and fillers to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating layers are used in copper clad laminates, then manufacturing simplicity is maintained, but electrical performance (high Dk and Df) and heat resistance are insufficient
Solution Approach 1:
The patent employs composite insulating layers comprising multiple polymers (e.g., polyimide, polyester, epoxy) combined with fillers such as glass fiber, alumina, or silica. This composite approach enables simultaneous achievement of low dielectric constant (Dk < 5), low dissipation factor (Df < 0.01), and high heat resistance by leveraging the complementary properties of different materials in the composite system.
Solution Approach 2:
The patent systematically adjusts critical parameters including the ratio of different polymers, filler content (30-70 wt%), filler particle size (0.1-10 μm), and curing conditions to optimize the balance between Dk, Df, and thermal properties. By controlling these parameters, the laminate achieves superior electrical performance while maintaining manufacturing feasibility.
2Temperature
If cross-linkable copolymers with reactive functional groups are incorporated to increase cross-linking density, then heat resistance and adhesion are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent incorporates cross-linkable copolymers specifically in layers positioned adjacent to metal foils where enhanced adhesion and heat resistance are most critical. The copolymer contains reactive functional groups (vinyl, epoxy, isocyanate) that form cross-linked networks locally at the metal-polymer interface and in regions experiencing thermal stress, providing targeted enhancement without requiring cross-linking throughout the entire laminate structure.
Solution Approach 2:
The cross-linkable copolymer is pre-incorporated into the insulating layer formulation before lamination, with reactive groups already in place to initiate cross-linking during the subsequent curing process. This preliminary preparation ensures that when heat and pressure are applied during manufacturing, cross-linking occurs automatically at the optimal time and location, simplifying the overall manufacturing process while achieving enhanced performance.
3Reliability
If multiple insulating layers with specific compositions are implemented to achieve low Dk and Df, then electrical performance is improved, but device complexity increases
Solution Approach 1:
The patent divides the insulating structure into multiple layers, each with specialized composition and function. For example, layers adjacent to metal foils use copolymer-based compositions optimized for adhesion and low Df, while intermediate layers use glass fiber-reinforced compositions for mechanical stability and low Dk. This segmentation allows each layer to be optimized independently for its specific function, achieving overall superior electrical performance.
Solution Approach 2:
Different insulating layers are assigned different compositions based on their specific functional requirements within the laminate. Layers requiring low Df (adjacent to conductors) use copolymer formulations with reactive groups, while layers requiring low Dk and high mechanical strength use glass fiber composites. This local optimization of material properties minimizes the need for excessive numbers of layers while achieving target 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
The laminate achieves a dielectric constant (Dk) of <5 and dissipation factor (Df) of <0.01 at 10 GHz, providing enhanced electrical and mechanical properties suitable for high-frequency and heat-resistant applications.
Implementation Method 1
The incorporation of a cross-linkable copolymer offers several advantages, including high heat resistance, as well as desirable properties like low dielectric constants (Dk) and minimal dissipation factors (Df). These copolymers can be tailored with reactive functional groups such as vinyl or epoxy, promoting increased cross-linking density during curing.
Data Source
AI summary
The disclosure relates to a multi-layered laminate comprising multiple metal foil layers and multiple dielectric (insulating) layers. At least one of the insulating layers includes a copolymer containing diisoalkenylarene (DIAEA) and divinylarene (DVA) units, optionally combined with a filler and/or another dielectric polymer. Another insulating layer includes another dielectric polymer distinct from the DIAEA-DVA copolymer. At least one copolymer-containing insulating layer is positioned adjacent to a metal foil layer. This copolymer layer enhances thermal stability at elevated temperatures and provides improved electrical performance such as reduced dielectric constant (Dk) and dissipation factor (Df) along with excellent processability.