Stepped Substrate Profile for Recessed TOSA Mounting
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Solution Overview
Problem
High-speed optical transmission systems face challenges in reducing electrical interconnection lengths between TOSA modules and substrates without increasing design and manufacturing complexity, which affects signal quality and limits transmission speeds due to vertical offsets and long wire bond lengths.
Innovation Solution
A substrate with a stepped profile that allows TOSA modules to be mounted in a recessed orientation, reducing the distance between substrate terminals and TOSA components, thereby shortening electrical interconnections and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TOSA modules are mounted on a flat substrate surface, then manufacturing is simple, but electrical interconnection lengths are long causing signal degradation
Solution Approach 1:
The substrate transitions from a flat two-dimensional surface to a three-dimensional stepped structure. The first mounting surface is positioned at a higher elevation than the second mounting surface, creating a vertical dimension that reduces the path length of electrical interconnections between TOSA modules and RF terminals while maintaining a manageable structural complexity
2Productivity
If transmission speeds are increased to 400 Gbp/s, then bandwidth is improved, but mounting and electrical interconnection complexity increases
Solution Approach 1:
The substrate is segmented into distinct mounting regions with different elevation levels. The first mounting surface accommodates TOSA modules while the second mounting surface provides access points for RF terminals, allowing electrical interconnections to be made in stages rather than requiring complex through-substrate routing
Data Source
AI summary
The present disclosure is generally directed to a stepped profile for substrates that support “on board” optical subassembly arrangements. The stepped profile enables mounting TOSA modules to the substrate in a recessed orientation to reduce the overall distance between terminals of the substrate and associated components of the TOSA, e.g., RF terminals of the substrate and an LDD of the TOSA. In an embodiment, the stepped profile further simplifies mounting and optical alignment of TOSA modules by providing at least one mechanical stop to engage surfaces of the TOSA modules and limit travel by the same along one or more axis.