PCB Shield Case Spring Contact for Cavity Resonance Control
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Solution Overview
Problem
Existing RF circuit designs face challenges in predicting and controlling cavity resonance frequencies, necessitating trial and error in determining groove shapes for radio wave absorbers, which complicates design and increases man-hours.
Innovation Solution
A high-frequency circuit with a shield case featuring a connection conductor, such as a spring contact, electrically connecting the ground of the printed circuit board to the lid portion of the shield case, allowing for precise control of cavity resonance frequency through electromagnetic field simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the size of the space partitioned by the shield case is increased to facilitate component arrangement, then the ease of manufacture and design simplicity is improved, but the cavity resonance frequency decreases, worsening the isolation performance
Solution Approach 1:
The invention changes the physical parameters of the shield case by adding connection conductors that protrude into the internal space. These conductors effectively reduce the resonant cavity dimensions without changing the actual external size of the shield case, thereby increasing the cavity resonance frequency while maintaining the larger physical dimensions needed for component arrangement.
Solution Approach 2:
The connection conductors serve as intermediary elements that simultaneously perform multiple functions: they provide electrical connection between circuit blocks and acts as parasitic elements that modify the cavity resonance characteristics. This intermediary structure allows the shield case to maintain both large physical size for component placement and high resonance frequency for isolation performance.
2Reliability
If a radio wave absorber is used to suppress cavity resonance, then the isolation performance is improved, but the device complexity and design time increase due to trial and error in determining groove shapes
Solution Approach 1:
The invention extracts the resonance suppression function from complex radio wave absorbers with grooves and replaces it with simple connection conductors that are integral parts of the circuit board design. These conductors naturally create parasitic effects that suppress cavity resonance without requiring additional absorptive materials or complex geometric features.
Solution Approach 2:
The connection conductors use simple, inexpensive metallic traces or protrusions that are already part of the PCB structure, replacing expensive and complex radio wave absorber materials. The design can be easily modified by changing conductor parameters without requiring costly material substitutions or complex manufacturing processes.
3Reliability
If the cavity resonance frequency is increased to suppress resonance, then the isolation performance is improved, but the space size must be reduced, worsening the ease of component arrangement
Solution Approach 1:
The invention addresses the dimensional conflict by operating in a different dimensional space. Instead of reducing the physical dimensions of the shield case interior, it introduces elements (connection conductors) that electromagnetically reduce the effective resonant cavity size. This allows the physical space to remain large for component placement while the electromagnetic resonance characteristics correspond to a smaller cavity.
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 enables predictable and effective suppression of cavity resonance, reducing design man-hours and facilitating component placement while maintaining electrical connectivity, even with larger shield case spaces.
Implementation Method 1
A cavity resonance frequency of a space partitioned by the shield case is determined by a size and a shape of the space. At the cavity resonance frequency, the isolation of the space is 0 dB
Implementation Method 2
the disposition of the connection conductor, which increases the cavity resonance frequency to be higher than the operating frequency, can be predicted through electromagnetic field simulation
Implementation Method 3
the connection conductor may be a spring contact (15) including a contact portion (17) that elastically comes into contact with the ceiling surface
Data Source
AI summary
A high-frequency circuit includes a printed circuit board on which a circuit including a plurality of electronic components is disposed, a shield case that is electrically connected to a ground of the printed circuit board and covers the circuit, and at least one spring contact that is electrically connected to the ground in a space formed by the printed circuit board and an inner wall of the shield case, in which the shield case includes a frame that is surface-mounted on the ground and is electrically connected to the ground, and a cover that includes a ceiling surface facing the printed circuit board and is electrically connected to the frame by being in contact with the frame, and the spring contact electrically connects the ground and the cover by being in contact with a part of the ceiling surface.