Aerogel PCB Laminates for Low-Loss Signals and Heat Resistance
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Solution Overview
Problem
Conventional copper-clad laminates used in printed circuit boards (PCBs) have dielectric constants greater than 2.0, which hinder signal propagation in high-frequency applications like 5G communications and high-speed digital circuits, and are prone to thermal delamination due to substrate expansion.
Innovation Solution
The laminates incorporate electrically-conductive copper layers with electrically-insulative layers containing porous materials, such as polymeric aerogels, which have ultra-low dielectric constants (less than 2.0) and dissipation factors (less than 0.002 at 10 GHz), along with adhesive layers to enhance bonding and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional substrates (PTFE, epoxy resin, paper) are used in copper-clad laminates, then the laminate provides structural support and electrical insulation, but the dielectric constant remains greater than 2.0 which limits signal propagation speed in high-frequency applications
Solution Approach 1:
The patent uses composite materials by combining aerogel particles (silica, alumina, titania, zirconia, or their combinations) with polymer matrices (polyimide, polyester, polyethylene terephthalate, or their blends) to create a substrate with ultra-low dielectric constant less than 2.0. The aerogel particles provide low dielectric constant while the polymer matrix provides structural support, achieving both high signal propagation speed and signal integrity.
Solution Approach 2:
The patent incorporates porous aerogel materials with controlled pore structures into the substrate. The aerogel particles have high porosity (typically 80-99%) which significantly reduces the dielectric constant of the composite substrate. The porous structure allows for low dielectric constant while maintaining mechanical integrity through the polymer matrix, enabling signal propagation at speeds corresponding to dielectric constants less than 2.0.
2Temperature
If the substrate temperature is raised above its glass transition temperature during soldering or PCB operation, then the substrate undergoes thermal expansion, but this causes delamination of copper layers and breakage of component joints
Solution Approach 1:
The patent changes the thermal parameters of the substrate by selecting polymer matrices with high glass transition temperatures (polyimide: Tg > 250°C, polyester: Tg > 70°C, polyethylene terephthalate: Tg > 70°C) and incorporating aerogel particles with exceptional thermal stability. This allows the substrate to withstand soldering temperatures and operational heat without undergoing significant thermal expansion, preventing delamination and joint breakage while maintaining structural integrity.
Solution Approach 2:
The composite structure of aerogel particles embedded in high-heat-resistant polymer matrices provides both thermal stability and structural integrity. The aerogel particles (silica, alumina, titania, zirconia) have low thermal expansion coefficients and high thermal stability, while the polymer matrix provides mechanical strength. This combination allows the substrate to resist thermal expansion during soldering and operation, preventing delamination and maintaining structural integrity.
3Reliability
If porous materials like aerogel are incorporated into the electrically-insulative layers, then the dielectric constant is reduced to less than 2.0, but the structural strength and mechanical support may be compromised
Solution Approach 1:
The patent creates a composite material system where aerogel particles (providing low dielectric constant) are dispersed and embedded within a continuous polymer matrix (providing mechanical strength). The polymer matrix acts as a binding phase that holds the aerogel particles together, maintaining substrate strength and mechanical support. This composite structure achieves dielectric constants less than 2.0 while preserving structural integrity through the synergistic combination of aerogel and polymer phases.
Solution Approach 2:
The patent applies local quality by distributing aerogel particles non-uniformly within the polymer matrix, concentrating the low-dielectric constant material in specific regions while maintaining polymer matrix continuity for structural support. The aerogel content can be optimized locally (typically 1-50 wt%) to achieve the desired dielectric constant while ensuring sufficient mechanical strength. This localized optimization allows simultaneous achievement of signal propagation quality and substrate strength.
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 laminates provide superior signal propagation and thermal stability, suitable for high-frequency applications by maintaining signal integrity and withstanding heat during manufacturing and use.
Implementation Method 1
the rate at which signals can be propagated through the PCB and the amount of the signals' electromagnetic energy lost to the PCB is affected by the laminate's dielectric constant (Dk) and dissipation factor (Df)
Implementation Method 2
the porous material can be an aerogel. In some laminates, the electrically-insulative layer(s) each can comprise a layer of polymeric aerogel. With such aerogel layer(s), the laminate can have an ultra-low dielectric constant (e.g., that is less than 2.0, such as less than or equal to 1.7 at 10 GHz) and dissipation factor
Implementation Method 3
adhesive layers to enhance bonding and heat resistance
Implementation Method 4
the laminates provide superior signal propagation and thermal stability, suitable for high-frequency applications by maintaining signal integrity and withstanding heat during manufacturing and use
Data Source
AI summary
A laminate that includes at least two electrically-conductive layers that include a first electrically-conductive layer and a second-electrically conductive layer, and at least one electrically-insulative layer that includes an organic polymeric aerogel is disclosed. The electrically-insulative layer can be positioned between the first electrically-conductive layer and the second electrically conductive layer. The at least a portion of a front surface of the laminate can be defined by the first electrically-conductive layer. At least a portion of a back surface of the laminate can be defined by the second electrically-conductive layer.