High-Speed FPC Using FRCC and Low-Temperature Lamination
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Solution Overview
Problem
Current high-frequency and high-speed flexible printed circuits (FPCs) face challenges with signal losses and manufacturing limitations due to the use of materials like LCP and PTFE, which require high-temperature processing, result in non-uniform film thickness, and have poor electrical and mechanical properties, limiting their reliability and transmission speed.
Innovation Solution
A high-frequency and high-transmission speed FPC is developed using flexible resin coated copper (FRCC) with a laminated structure comprising low-Dk/Df resin layers and copper foil layers, featuring a low surface roughness, stable dielectric properties, and a simple manufacturing process, allowing for low thermal expansion and excellent mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature lamination process (>280°C) is used to ensure bonding strength, then peel strength is improved, but film thickness uniformity deteriorates and resistance value control becomes difficult
Solution Approach 1:
The patent changes the lamination temperature parameter from traditional high-temperature (>280°C) to low-temperature (180-220°C) processing. This parameter change enables the use of low-Dk/Df resin materials that maintain film thickness uniformity and resistance value control while achieving sufficient bonding strength through optimized pressure and time parameters
Solution Approach 2:
The patent employs composite material structure combining low-Dk/Df resin with copper foil layers. This composite approach allows the resin to provide both bonding strength and electrical property stability, eliminating the need for high-temperature processing that causes film thickness non-uniformity
2Strength
If high-temperature lamination process is used to ensure bonding strength, then peel strength is improved, but conductivity of plated copper deteriorates due to squeezing
Solution Approach 1:
The patent reduces lamination temperature from high-temperature (>280°C) to low-temperature (180-220°C) range, preventing thermal squeezing of the plated copper layers. This parameter change maintains copper conductivity while achieving adequate bonding strength through controlled pressure and time parameters
Solution Approach 2:
The patent introduces low-Dk/Df resin as an intermediary material that enables bonding at low temperatures. This resin acts as a mediator that provides sufficient adhesive strength without requiring the high temperatures that would cause copper squeezing and conductivity degradation
3Manufacturing precision
If quick press is not used to maintain film quality, then film thickness uniformity is improved, but processing efficiency deteriorates
Solution Approach 1:
The patent changes the processing temperature parameter to low-temperature (180-220°C) range, which allows the use of quick press technology. This parameter change enables both film thickness uniformity maintenance and processing efficiency improvement by combining quick press with optimized pressure and time parameters
4Reliability
If low-Dk/Df resin layers are used to improve electrical properties, then signal integrity is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent creates a composite material system combining low-Dk/Df resin with copper foil layers and appropriate adhesive formulations. This composite structure allows the resin to provide excellent electrical properties (low Dk/Df) while the copper layers and adhesive system compensate for mechanical strength requirements
Solution Approach 2:
The patent applies different material properties to different layers: low-Dk/Df resin for electrical performance in signal transmission paths, while copper foil layers and adhesive layers provide mechanical strength. This local quality differentiation allows optimization of both electrical and mechanical properties in their respective locations
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 FPC achieves improved signal integrity, reduced insertion loss, and enhanced mechanical strength, with a cost-effective and efficient production process suitable for high-density assembly and UV laser processing, while maintaining high-frequency and high-speed performance.
Implementation Method 1
FRCC is mainly formed by a plurality of insulating layers and copper foil layers
Implementation Method 2
the inner surface of the third copper foil layer has an Rz value of 0.1-1.0 μm... low-roughness copper foil layers
Implementation Method 3
The performance of the FRCC, to a large extent, depends on the selection of low-Dk/Df resin layers
Data Source
AI summary
A high-frequency and high-transmission speed FPC with FRCC. The FPC includes FRCC and a double-sided board laminated again each other. The FRCC includes a third copper foil layer, a second ultra-low dielectric adhesive layer and a second insulating layer located between the third copper foil layer and the second ultra-low dielectric adhesive layer. One surface of the third copper foil layer is an inner surface. The double-sided board includes a first copper foil layer, a second copper foil layer and a first insulating layer located between the first copper foil layer and the second copper foil layer. An inner surface of the first copper foil layer has an Rz value of 0.05-0.5 μm. An inner surface of the second copper foil layer has an Rz value of 0.1-1.10 μm. The FPC has a good electrical property, a simple structure, a cost advantage, a brief preparation process, and a low thermal expansion coefficient.