Optical Module Bridge Substrate Signal Integrity
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Solution Overview
Problem
High-speed communication systems face signal loss and degradation due to parasitic inductive components in bonding wires connecting optical modules, leading to impedance mismatch and reduced reliability when the top surfaces of LD devices and wiring substrates are uneven.
Innovation Solution
The optical module employs a bridge substrate that connects the wiring substrate with the LD element, using compensating substrates made of the same material as the wiring and semiconductor substrates, respectively, to maintain even thickness and alignment, thereby reducing parasitic inductive components and signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bonding wires are used to connect the transmission line with the LD device, then the connection is simple and low-cost, but parasitic inductive components increase causing signal loss and degradation
Solution Approach 1:
A bridge substrate is introduced as an intermediary component between the wiring substrate and the LD device. This bridge substrate provides a transmission line that directly connects to the LD device's electrode, eliminating the need for bonding wires and their associated parasitic inductances. The bridge substrate acts as a mediator that improves signal integrity while maintaining manufacturing feasibility.
2Adaptability or versatility
If the top surfaces of the LD device and wiring substrate are uneven, then manufacturing flexibility is improved, but connection reliability via bridge substrate deteriorates
Solution Approach 1:
The bridge substrate is designed to extend from the wiring substrate to the LD device in a manner that compensates for surface unevenness. By utilizing the third dimension (vertical extension and positioning), the bridge substrate can bridge gaps and accommodate height differences between components, ensuring reliable electrical connection despite manufacturing variations in surface flatness.
3Reliability
If a bridge substrate is used to connect the wiring substrate with the LD device, then signal loss is reduced, but device complexity increases
Solution Approach 1:
The bridge substrate is designed to perform multiple functions: it provides electrical connection between the wiring substrate and LD device, serves as a support structure, and acts as a transmission line for high-frequency signals. By consolidating these functions into a single component, the overall device complexity is minimized while achieving improved signal integrity.
Data Source
AI summary
An optical module that provides a bridge substrate for carrying a driving signal from a wiring substrate to a laser diode (LD) element is disclosed. The optical module provides a carrier, first and second assemblies, and the bridge substrate. The first assembly, which includes the LD element, stacks a first compensating substrate and a semiconductor substrate on the carrier, where the semiconductor substrate includes the LD element. The second assembly stacks a second compensating substrate and the wiring substrate on the carrier. The first compensating substrate is made of a material same with a material of the wiring substrate and has a thickness same with that of the wiring substrate. The second compensating substrate is made of a material same with a material of the semiconductor substrate and has a thickness same with that of the semiconductor substrate.