Optical Module Air Layer Impedance Matching
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Solution Overview
Problem
Current optical modules face challenges in achieving both downsizing and high frequency characteristics due to the need for physical space to match characteristic impedance, leading to inconsistencies in signal transmission, especially at high frequencies like 56 Gbit/s, and are costly due to the use of thick gold plating and diverse FPC layouts.
Innovation Solution
An optical module design featuring an eyelet with a penetration hole where a lead pin is inserted, with a pedestal and relay board for electrical connection, using an air layer instead of glass for the first lead pin to reduce permittivity and eliminate impedance inconsistencies, and a flat surface connection to the relay board for impedance matching up to high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is used as dielectric material in penetration holes to support lead pins, then the lead pins are electrically insulated and mechanically supported, but the high relative permittivity of glass requires large physical space for impedance matching, preventing downsizing
Solution Approach 1:
The patent removes the glass dielectric material from the penetration hole, extracting the harmful high permittivity element while maintaining electrical insulation through an alternative structure where the lead pin is surrounded by air and the penetration hole wall acts as the insulating barrier
Solution Approach 2:
The patent changes the dielectric parameter from glass (εr=4-7) to air (εr≈1), fundamentally altering the permittivity to enable small penetration hole diameters while achieving proper impedance matching for high frequency signals
2Reliability
If glass dielectric is used in penetration holes, then lead pins are supported, but impedance inconsistency occurs at high frequencies (56 Gbit/s), making signal transmission difficult
Solution Approach 1:
The patent extracts the glass dielectric material that causes impedance inconsistency, replacing it with air to achieve consistent impedance characteristics across the frequency range including 56 Gbit/s signals
Solution Approach 2:
The patent creates a homogeneous air-filled environment around the lead pin in the penetration hole, eliminating the heterogeneous glass-air interface that causes impedance discontinuities and signal transmission problems at high frequencies
3Ease of manufacture
If non-hermetic structure with direct FPC connection is used, then manufacturing is simplified, but thick gold plating is required for wire pull strength, increasing cost
Solution Approach 1:
The patent replaces the expensive thick gold plating with a conventional lead pin structure that uses standard, cost-effective materials and manufacturing processes, achieving the same functional result at lower cost
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
This design balances downsizing with high frequency characteristics by eliminating impedance inconsistencies and reducing costs through simplified FPC connections, ensuring efficient signal transmission and cost-effectiveness.
Implementation Method 1
The lead pin is in no contact with an inner surface of the penetration hole. The lead pin has a flat surface which is at least a part of a surface bonded to the transmission line
Data Source
AI summary
An optical module includes an eyelet having a first surface, a second surface opposite to the first surface, and a penetration hole penetrating from the second surface to the first surface; a lead pin in the penetration hole, for transmitting electric signals; a pedestal protruding from the first surface in an extension direction of the lead pin; and a relay board on the pedestal, the relay board having a transmission line for electrically connecting an optical element and the lead pin. The lead pin is in no contact with an inner surface of the penetration hole. The lead pin has a flat surface which is at least a part of a surface bonded to the transmission line.