TO Can Optical Module Substrate Impedance Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical modules for ultrahigh-speed communication face challenges in manufacturing transmission line substrates with limited size constraints, leading to signal distortion and impedance mismatch issues, making it difficult to achieve efficient high-speed signal transmission.
Innovation Solution
The optical module employs a two-substrate structure with a coupled thickness of 0.4 mm and a width of 0.6 mm or less for the upper substrate, allowing for impedance matching of 25 ohms or 50 ohms, and features a metal thin film on the lower substrate for grounding, enabling effective optical coupling and high-speed transmission within a narrow TO can-type package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a single substrate with thickness of 0.4 mm is used for high-speed signal transmission, then the substrate height is sufficient for optical coupling, but the substrate width becomes too large (exceeding 0.6 mm) to be embedded in narrow TO can-type package
Solution Approach 1:
The patent divides the substrate into two separate substrates: a first substrate with thickness of 0.1-0.3 mm for impedance-matched signal transmission, and a second substrate providing the remaining height to reach 0.4 mm total. This segmentation allows the signal transmission function to be performed by a narrow first substrate that fits within the TO can-type package, while the overall assembly maintains sufficient height for optical coupling.
2Area of stationary object
If substrate width is reduced to 0.6 mm or less to fit in narrow TO can-type package, then the package size is reduced, but impedance matching of 25 ohms or 50 ohms becomes difficult to achieve
Solution Approach 1:
The patent applies different substrate materials with different dielectric constants to different regions of the assembly. The first substrate has a dielectric constant of 3.0-10.0 optimized for impedance matching at 0.6 mm width, while the second substrate has a dielectric constant of 6.0-12.0 to complete the height requirement. This local optimization of material properties enables both narrow width and proper impedance matching to be achieved simultaneously.
3Ease of manufacture
If Au wire is used to connect laser diode chip and electrode pin, then electrical connection is achieved, but transmission signal distortion occurs at ultrahigh-speed
Solution Approach 1:
The patent extracts and eliminates the Au wire from the signal transmission path. Instead of using Au wire to connect the laser diode chip to the electrode pin, the invention uses a printed circuit board with impedance-matched transmission lines that directly connect the chip terminals to the package pins, removing the source of signal distortion while maintaining electrical connectivity.
Data Source
AI summary
A TO can-type optical module for ultrahigh-speed communication including a laser diode chip for at least 5 Gbps. A substrate for transmitting a signal to a laser diode chip is formed by coupling an upper substrate (210) on which line patterns for transmission are formed, to a lower substrate (220) of which an upper surface has conductivity with the upper substrate (210) such that the optical module for ultrahigh-speed communication has single ended impedance of 25 ohms or differential ended impedance of 50 ohms. The substrate has a height of about 0.4 mm to which a laser diode chip, for ultrahigh-speed communication, is attached to enable an optical coupling between the laser diode chip, the lens, and the like, and may implement a hight-speed transmission line using a width of 0.6 mm or less thereby providing a substrate which is effectively embedded ina TO can-type package with a narrow mounting area.