Optical Waveguide Board Oblique Core Bonding
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Solution Overview
Problem
Existing optical waveguide boards and packages face challenges in achieving high sealing reliability due to the bonding of lids to surfaces with irregularities, which compromises airtightness in element mount portions.
Innovation Solution
The optical waveguide board features a substrate with a cladding layer that includes a recess, element mount portions, and cores extending from the recess. The cladding layer has a frame-shaped joint area surrounding the recess and ridges along the cores, with at least one core having an oblique portion overlapping the joint area, enhancing the bonding area and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the lid is bonded to the cladding layer surface with irregularities, then the bonding area is reduced, but the sealing reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by forming the oblique portions on the core surfaces before the bonding process. These pre-formed geometric features ensure that when the lid is bonded to the cladding layer, the bond material naturally fills and contacts these inclined surfaces, increasing the effective bonding area and ensuring reliable sealing without requiring additional processing steps during assembly.
Solution Approach 2:
The patent transitions from a two-dimensional flat bonding surface to a three-dimensional structure with oblique portions extending at angles. By adding vertical and angular dimensions to the bonding interface through the inclined core surfaces, the effective bonding area is significantly increased, providing both larger contact area and mechanical interlocking for improved sealing reliability.
2Device complexity
If the cores are positioned directly over the recess without oblique portions, then the structure is simpler, but the distortion under thermal stress increases
Solution Approach 1:
The patent applies local quality by introducing oblique portions only in the specific regions where cores interact with the bonding interface, rather than modifying the entire core structure. This localized geometric modification at the bonding interface provides thermal stress resistance where needed, while maintaining the simplicity of the overall core design and minimizing additional structural complexity.
3Reliability
If the bonding area between lid and cladding layer is increased, then the sealing reliability improves, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the core structure with the bonding interface design by integrating the oblique portions directly into the core geometry. This combination means that the same structural features that define the core's optical path also serve to increase the bonding area, eliminating the need for separate bonding surface preparations and reducing overall manufacturing complexity while improving sealing reliability.
Data Source
AI summary
An optical waveguide board includes a substrate, a cladding layer including a recess on an upper surface, element mount portions defined in the recess, and a plurality of cores in the cladding layer. The plurality of cores extends from the element mount portions to outside the recess in a plan view. The cladding layer includes, on the upper surface, a joint area being frame-shaped and surrounding the recess, and includes a plurality of ridges extending along the cores. At least one of the plurality of cores includes a part overlapping the joint area in a plan view. The part includes an oblique portion extending in a direction oblique to a width direction from an outer peripheral edge toward an inner peripheral edge of the joint area in the cladding layer.