Supported Foam Circuit Laminate Compression Control
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Solution Overview
Problem
The processing of foamed dielectric substrates in circuit laminates is challenging due to compression issues, wrinkling, and chemical absorption during conventional circuit board manufacturing, particularly with open-celled foams, which affects the electrical properties of multi-layered circuits.
Innovation Solution
A method involving a support frame that fits around the dielectric foam substrate, providing rigid support and protection, allowing for co-lamination with an electrically conductive layer under heat and pressure, thereby reducing foam compression and wrinkling, and preventing chemical absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If foamed dielectric substrate is processed using conventional circuit board procedures, then standard processing can be used, but foam compression and wrinkling occur during lamination affecting electrical properties
Solution Approach 1:
A stress relief process is performed before lamination to pre-condition the foam substrate, removing internal stresses that would cause wrinkling and compression during subsequent lamination. This preliminary action allows conventional lamination procedures to be used without damaging the foam's dimensional stability or electrical properties.
2Strength
If foamed dielectric substrate is compressed during lamination, then bonding is achieved, but electrical properties of multi-layered circuits are adversely affected
Solution Approach 1:
The foam substrate undergoes a pre-lamination stress relief process that stabilizes its cellular structure before compression. This preliminary conditioning allows the foam to withstand lamination compression forces without collapsing or densifying, thereby maintaining both bonding strength and electrical properties.
3Reliability
If foamed dielectric substrate is used, then desirable dielectric and dissipation properties are provided, but susceptibility to chemical absorption at surfaces and edges increases
Solution Approach 1:
The highly susceptible edge regions of the foam substrate are removed by trimming or machining after lamination but before chemical processing. This extraction of vulnerable regions eliminates the primary sites for chemical absorption, allowing subsequent etching and chemical treatments to proceed without unwanted foam degradation.
Solution Approach 2:
The foam substrate edges are sealed or coated before chemical processing to prevent chemical absorption. This preliminary protective action blocks the harmful chemical interaction at the vulnerable edge surfaces while allowing the bulk foam to maintain its excellent dielectric properties.
4Reliability
If foamed material is used as dielectric substrate, then low dielectric constants and dissipation factors are achieved, but processing difficulties arise with open-celled foams
Solution Approach 1:
Open-celled foam substrates undergo a pre-lamination stress relief and stabilization process that temporarily reinforces their cellular structure. This preliminary action enables conventional lamination and processing equipment to handle the foam without causing excessive compression or damage, while the foam's inherent low dielectric properties are preserved.
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 enables the production of foam circuit laminates with improved compatibility with standard processing techniques, reduced foam compression, and minimized chemical absorption, eliminating the need for pre-lamination stress relief and enhancing dimensional stability during etching.
Implementation Method 1
foamed dielectric substrates can be susceptible to absorption of processing chemicals at the surface, edges, and through-hole walls of the foamed material
Implementation Method 2
wrinkling during lamination, which occurs as the foam material shrinks during cool down
Implementation Method 3
co-laminating the electrically conductive layer to the dielectric foam substrate and to the overlapped support frame under heat and pressure
Data Source
AI summary
A method of making a supported foam circuit laminate comprises fitting a dielectric foam substrate having a shape defined by edges to a support frame having a thickness, an inner rim and an outer rim, wherein the edges of the dielectric foam substrate are flush with the inner rim of the support frame, and the dielectric foam substrate has a thickness that is greater than the thickness of the support frame; disposing an electrically conductive layer onto a side of the dielectric foam substrate and the support frame, wherein the edges of the electrically conductive layer overlap the inner rim of the support frame; and co-laminating the electrically conductive layer to the dielectric foam substrate and the overlapped support frame under heat and pressure to provide a supported foam circuit laminate.