Ultrathin LCP Dielectric Layers for HDI PCB Signal Integrity
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Solution Overview
Problem
Current dielectric materials used in printed circuit boards, particularly glass-reinforced materials, face challenges in achieving thin, low-dissipation-factor, and low-dielectric-constant layers that are easily laser drillable, leading to issues with hole quality and limited thickness capabilities.
Innovation Solution
The use of a thermoplastic liquid crystal polymer (LCP) substrate coated or impregnated with a thermosetting resin as a dielectric material layer in printed circuit boards, which offers a low dielectric constant, low dissipation factor, and ultrathin thickness while being easily laser drillable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass-reinforced materials are used as dielectric layers, then structural strength and stability are improved, but laser drilling quality deteriorates and minimum thickness is limited
Solution Approach 1:
The patent uses a composite structure combining thermoplastic polymer matrix with thermoset resin impregnation. The thermoplastic provides structural strength and laser drillability, while the thermoset resin impregnated within provides dimensional stability and mechanical strength. This composite approach allows achieving both good laser drilling quality and structural strength simultaneously, overcoming the limitations of pure glass-reinforced materials.
2Reliability
If dielectric thickness is reduced to improve signal integrity, then signal quality is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent changes the material parameters by using thermoplastic polymers with specific properties (low dielectric constant, low dissipation factor) combined with thermoset resin impregnation. This material parameter change enables manufacturing of ultrathin dielectric layers (12-125 microns) while maintaining good manufacturability through laser drilling and lamination processes, thus achieving both signal integrity and ease of manufacture.
3Strength
If glass-reinforced materials are used, then dielectric strength is improved, but minimum achievable thickness increases
Solution Approach 1:
The patent employs thin film technology using thermoplastic polymer layers impregnated with thermoset resin. This approach enables achieving dielectric strengths sufficient for PCB applications while reducing the thickness to ultrathin ranges (12-125 microns). The flexible thermoplastic matrix combined with thermoset reinforcement allows maintaining dielectric strength at much thinner dimensions compared to traditional glass-reinforced materials.
Data Source
AI summary
Dielectric material layers including thermoplastic liquid crystal polymer (LCP) substrates coated or impregnated with a thermosetting resin. The dielectric material layers may have a dielectric constant (DK) value of less than about 3.4 and a dissipation factor of less than about 0.005 for use in printed circuit boards. The dielectric material layers may find particular utility in high density interconnect (HDI) printed circuit boards.