Flexible Printed Circuit Shield Layer for Radiation Image Capture
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Solution Overview
Problem
Radiation image capture devices using flexible printed circuits (FPCs) face issues with electrostatic charging due to touching and rubbing, leading to misdetected data and signal noise, as existing solutions like copper layers detach easily and antistatic layers cause stray capacitances and delays.
Innovation Solution
A radiation image capture device with a flexible printed circuit featuring a base film, wiring, a coating layer, and a shield layer connected to a fixed potential, which prevents electrostatic charging by eliminating static electricity and reducing the risk of detachment and stray capacitances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a copper layer is applied to suppress electrostatic charging, then electrostatic charging is suppressed, but the copper layer detaches when it touches the casing
Solution Approach 1:
The patent applies a multi-layer composite structure consisting of a base film, wiring layer, insulating coating layer, and shield layer. This composite structure combines materials with different properties: the shield layer (conductive) suppresses electrostatic charging, while the insulating coating layer prevents detachment by providing adhesion and isolation from the casing, resolving the contradiction between electrostatic suppression and layer stability.
Solution Approach 2:
The insulating coating layer acts as an intermediary between the shield layer and the external environment (casing). It mediates the interaction by preventing direct contact between the conductive shield layer and the casing, thereby eliminating the detachment problem while preserving the electrostatic shielding function.
2Reliability
If the thickness of the copper layer is increased to prevent detachment, then detachment is reduced, but flexibility of the flexible printed circuit is impaired
Solution Approach 1:
Instead of increasing the thickness of a single copper layer, the patent uses a thin shield layer combined with a separate insulating coating layer. This composite approach maintains flexibility because the individual layers remain thin, while the combination provides both detachment prevention and electrostatic shielding functionality.
Solution Approach 2:
The patent segments the protective function into two separate thin layers: a shield layer for electrostatic charging suppression and an insulating coating layer for detachment prevention. This segmentation allows each layer to remain thin and flexible while collectively providing the required protection without compromising the overall flexibility of the flexible printed circuit.
3Object-affected harmful factors
If an antistatic layer is formed to suppress electrostatic charging, then electrostatic charging is suppressed, but stray capacitances are produced causing signal delays
Solution Approach 1:
The patent uses a shield layer that replicates the electrostatic charging suppression function of antistatic layers but with improved electrical characteristics. The shield layer, being conductive and connected to ground, provides electrostatic protection without creating the stray capacitances that plague antistatic layers, thus avoiding signal delays.
Solution Approach 2:
The patent changes the electrical parameter of the charging suppression layer from high impedance (antistatic) to low impedance (conductive shield layer grounded). This parameter change eliminates stray capacitance effects because the grounded conductive shield provides a low-impedance path for electrostatic charges without creating significant capacitive coupling with signal lines, thereby preventing signal delays.
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 solution effectively suppresses electrostatic charging, preventing misdetected data and signal delays, while maintaining the flexibility of the FPC and avoiding the issues of detachment and stray capacitances in existing technologies.
Implementation Method 1
electrostatic charging occurs at wiring of the flexible printed circuit, and counter (compensation) charges are produced
Implementation Method 2
a shield layer provided between the base film and the wiring or between the wiring and the coating layer, with an insulator interposed between the shield layer and the wiring, and the shield layer connected to a fixed potential
Data Source
AI summary
A radiation image capture device is provided with a radiation detection panel including optoelectronic conversion elements, a signal processing board that performs signal processing of the signals provided by the radiation detection panel, a flexible printed circuit, and a casing. One end of the flexible printed circuit is connected to the radiation detection panel and the other end is connected to the signal processing board. The flexible printed circuit includes a base film fowled of an insulating resin film, wiring disposed over the base film, a coating layer formed of an insulating resin disposed over the wiring, and a shield layer provided between the base film and the wiring and/or between the wiring and the coating layer. An insulator is interposed between the shield layer and the wiring, and the shield layer is connected to a fixed potential.