Optical Package Interposer Alignment via Eutectic Bonding
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Solution Overview
Problem
In optical systems, misalignment of optical devices due to adhesive volume or shape changes during curing affects optical performance, leading to tilting, shifting, or rotation of optical devices, which compromises sensing accuracy and light deviation.
Innovation Solution
An optical package structure featuring a substrate with a silicon interposer bonded through a bonding layer, where the interposer has a larger area than the optical device, and eutectic alloys are used for bonding to minimize tilting and rotation by constraining the orientation changes during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to bond the optical device to the substrate, then the optical device can be fixed in place, but the adhesive volume or shape changes during curing cause misalignment and tilting of the optical device
Solution Approach 1:
The patent introduces an interposer as an intermediary component between the optical device and the substrate. This interposer has a larger area than the optical device and provides a stable bonding platform that prevents misalignment during adhesive curing. The interposer acts as a mediator that decouples the optical device from the substrate, eliminating the direct transmission of curing-induced deformation to the optical device.
Solution Approach 2:
The patent extends the bonding interface from a small area (optical device footprint) to a larger area (interposer footprint) by adding spatial dimension. This area expansion in another dimension provides greater mechanical stability and distributes the curing stress over a larger region, preventing tilting and misalignment of the optical device.
2Device complexity
If the optical device is directly bonded to the substrate, then the structure is simple, but misalignment occurs due to adhesive curing changes
Solution Approach 1:
The interposer serves as a mediator layer that improves optical alignment reliability without significantly complicating the overall package structure. It provides a stable reference plane for optical device mounting and isolates the device from substrate deformation during adhesive curing.
Solution Approach 2:
The interposer provides beforehand cushioning by creating a compliant interface that absorbs and distributes the mechanical stress generated during adhesive curing. This pre-established cushioning structure prevents misalignment before it occurs, ensuring reliable optical positioning.
3Manufacturing precision
If the interposer area is larger than the optical device area, then misalignment is reduced, but the device complexity increases
Solution Approach 1:
The patent utilizes area expansion in the planar dimension (top view) rather than increasing vertical height or complexity. The interposer extends laterally beyond the optical device footprint, providing mechanical stability and alignment precision through increased surface area without adding significant structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces tilting angles and displacement of optical devices, enhancing the accuracy and reliability of optical systems by maintaining the original optical path design.
Implementation Method 1
illuminating, by a light source, the eutectic alloys to bond the optical device to the interposer
Implementation Method 2
an interposer bonded to the first surface through a bonding layer
Data Source
AI summary
An optical package structure includes a substrate having a first surface, an interposer bonded to the first surface through a bonding layer, the interposer having a first area from a top view perspective, and an optical device on the interposer, having a second area from the top view perspective, the first area being greater than the second area. A method for manufacturing the optical package structure is also provided.