Low Stress Package With Limited Contact Bonding
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Solution Overview
Problem
Existing packages for planar lightwave circuits (PLCs) apply stress to the substrates due to low modulus adhesives, leading to deformation of waveguides and reduced performance, as well as mechanical weakness in the structure.
Innovation Solution
A package design where the PLC substrate is bonded to a carrier through a limited contact area, with a high modulus adhesive or solder, allowing the remaining substrate surface to be detached from the carrier, thereby confining stress to a small area and reducing mechanical strain on the optical circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the entire underlying surface of the PLC substrate is bonded to the carrier with a low modulus adhesive, then stress applied to the PLC substrate is reduced, but the mechanical strength of the package structure becomes weak
Solution Approach 1:
The bonding between the PLC substrate and carrier is segmented into discrete bonding regions rather than continuous bonding. The bonding layer is configured with specific patterns (e.g., at corners, edges, or as isolated patches) that provide mechanical anchoring while leaving most of the substrate surface unbonded, thus reducing stress transmission to the optical circuit while maintaining structural strength.
2Stress or pressure
If a low modulus adhesive is used to bond the PLC substrate to the carrier, then stress is reduced, but the package structure lacks mechanical robustness
Solution Approach 1:
Different regions of the PLC substrate have different bonding characteristics. The bonding layer is strategically positioned in specific locations (such as corners, edges, or peripheral regions) rather than uniformly across the entire substrate. This local quality approach allows the bonded regions to provide mechanical strength and anchoring while the unbonded regions maintain stress-free conditions for the optical circuit.
3Stability of the object's composition
If the PLC substrate is fully bonded to the carrier, then mechanical stability is improved, but waveguide deformation occurs due to applied stress
Solution Approach 1:
The bonding is segmented into discrete regions that provide mechanical stability without fully constraining the substrate. By positioning bonding layers at specific locations (corners, edges, or as isolated patches), the substrate remains stable enough for handling and assembly while the unbonded regions allow the optical circuit to maintain its precise geometric dimensions free from stress-induced deformation.
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 design results in a more robust mechanical structure with reduced stress on the PLC, minimizing performance degradation and enhancing the stability of the optical circuit, allowing for precise maintenance of waveguide lengths and improved performance.
Implementation Method 1
The package includes a bonding layer provided between a the chip and the carrier
Data Source
AI summary
Consistent with the present disclosure, a package is provided in which the PLC substrate, for example, is bonded to the underyling carrier though a limited contact area. The rest of the substrate is detached from the carrier so that stresses are applied to a limited portion of the PLC substrate. The PLC itself, however, is provided over that portion of the substrate that is detached from the carrier, and thus experiences reduced stress. Accordingly, high modulus adhesives, as well as solders, may be used to bond the PLC substrate to the carrier, thereby resulting in a more robust mechanical structure.