Protrusion Dam Protecting Metallic Films in Optical Waveguides
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Solution Overview
Problem
In substrates with optical waveguides, the metallic film can become stripped or detached during the development process of the core layer, leading to optical losses.
Innovation Solution
A substrate with an optical waveguide is designed with a first metallic film forming protrusion having an inclined surface, a core layer covering a portion of the metallic film, and a pair of protrusions formed of photosensitive resin, which reduces the risk of metallic film stripping by acting as dams for the developer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the core layer is exposed and developed after forming the metallic film, then the optical waveguide structure can be formed, but the metallic film may become stripped or detached by the developer
Solution Approach 1:
The patent forms protective protrusions from the cladding layer before developing the core layer. These protrusions extend over the metallic film regions and act as barriers that prevent developer solution from contacting and detaching the metallic film during the development process, thus protecting the metallic film integrity in advance
Solution Approach 2:
The protective protrusions formed from the cladding layer material serve as an intermediary barrier between the developer solution and the metallic film. This intermediate structure prevents direct contact between the harmful developer and the vulnerable metallic film, allowing the development process to proceed without damaging the metallic film
Data Source
AI summary
An optical waveguide on a wiring substrate includes a first cladding layer, a first metallic film forming protrusion formed on the first cladding layer and including an inclined surface inclined with respect to an upper surface of the first cladding layer, a first metallic film formed on at least the inclined surface, a core layer formed on the first cladding layer so as to cover a portion of the first metallic film, a second cladding layer formed on the first cladding layer, so as to cover at least an upper surface and both side surfaces of the core layer, and a pair of first protrusions formed on the first cladding layer with the core layer interposed therebetween in a plan view and protruding from the first cladding layer, so as to be separated from the core layer and the first metallic film forming protrusion.