Circuit Board Contact Pad Attenuation Reduction via Expanded Thickness
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Solution Overview
Problem
Current circuit boards with flexible substrates face issues in high frequency signal transmission due to poor impedance matching, parasitic capacitance, and signal reflection, which are exacerbated by the small line widths of high frequency signal lines and large component dimensions, leading to attenuation and loss of high frequency signals.
Innovation Solution
An expanded thickness is introduced between high frequency signal contact pads and the grounding layer of the circuit board, increasing the distance between them and reducing capacitance effects, thereby improving signal transmission quality by using thickness-expanding pads or a thickened bonding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the substrate thickness is reduced to make the circuit board flexible, then the flexibility and bendability are improved, but the capacitance effect between contact pads and grounding layer increases causing signal attenuation
Solution Approach 1:
The patent applies local quality by creating a thickness-expanding pad structure specifically at the contact pad mounting zone, while keeping other areas of the substrate at normal thickness. This localized thickening increases the distance between the contact pad and grounding layer only where high frequency signals are transmitted, reducing parasitic capacitance and signal attenuation without compromising the overall flexibility of the circuit board.
Solution Approach 2:
The patent addresses the capacitance issue by transitioning from a two-dimensional planar design to a three-dimensional structure. By adding vertical thickness to the substrate at the contact pad area (creating a thickness-expanding pad), the patent increases the separation distance between the contact pad and grounding layer in the vertical dimension, thereby reducing parasitic capacitance while maintaining the flexible nature of the circuit board.
2Manufacturing precision
If the line width of high frequency signal lines is reduced to match small connector pins, then the connection precision is improved, but the characteristic impedance matching deteriorates causing signal reflection
Solution Approach 1:
The patent applies parameter changes by modifying the substrate thickness parameter locally at the contact pad area. By increasing the thickness to create a thickness-expanding pad, the patent changes the electrical characteristics (capacitance, impedance) of the contact pad mounting zone, enabling better impedance matching for high frequency signals while maintaining the required small line widths for precise connector connections.
3Length of stationary object
If the distance between contact pad and grounding layer is reduced to minimize board thickness, then the overall thickness is decreased, but the parasitic capacitance increases causing signal loss
Solution Approach 1:
The patent applies segmentation by dividing the substrate into different thickness zones: a normal thickness area for general purposes and a localized thickness-expanding pad area at the contact pad mounting zone. This segmentation allows the circuit board to maintain overall thinness and flexibility while creating a specific region with increased thickness to reduce parasitic capacitance and signal attenuation at critical high frequency signal paths.
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 increased distance between high frequency signal contact pads and the grounding layer reduces capacitance-induced signal loss and reflection, ensuring better transmission quality of high frequency signals by minimizing attenuation and maintaining signal integrity.
Implementation Method 1
an expanded thickness formed between high frequency signal contact pads and a grounding layer of a circuit board to increase a corresponding distance between the high frequency signal contact pads and the grounding layer, reducing reflection and loss of high frequency components of transmitted signals
Data Source
AI summary
An attenuation reduction structure of a circuit board includes an expanded thickness formed between high frequency signal contact pads and a grounding layer of the circuit board. The expanded thickness is greater than a reference thickness between the grounding layer and high frequency signal lines. The circuit board is made of polyethylene terephthalate (PET) or polyimide (PI). Alternatively, a rigid board including resin and fibrous material or a rigid-flex board is used. The circuit board can be a single-layer circuit board or a multi-layer board formed by combining at least two single-layer circuit boards. A thickness-expanding pad is mounted between the high frequency signal contact pads and the grounding layer or the thickness of a portion of a bonding layer of the circuit board is increased to provide an expanded thickness.