Bonded Structure Tilt Angle via Pad Size Variation
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Solution Overview
Problem
Conventional flip-chip mounting techniques for photonic integrated circuits (PICs) face complexity and reliability issues due to the need for differently dimensioned connectors to achieve the required tilt angle for efficient optical coupling, leading to imperfections and complications in the fabrication process.
Innovation Solution
A method using a single type of connection elements with nominal variations in surface sizes of bonding pads on the dies to achieve the desired tilt angle, where the connection elements distribute across the pads during a reflow process, ensuring a consistent tilt angle between the integrated circuit and substrate components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If differently dimensioned connectors are used to achieve the desired tilt angle, then the tilt angle is achieved, but the fabrication process becomes complicated and reliability decreases
Solution Approach 1:
The patent changes the parameter of connector dimensions from variable to uniform, and instead achieves the tilt angle by varying the pad surface sizes. This resolves the contradiction by maintaining manufacturing precision through pad geometry control while simplifying the fabrication process through uniform connector dimensions.
Solution Approach 2:
The patent applies local quality by creating non-uniform pad surface sizes at specific locations while keeping connectors uniform. The varying pad areas locally compensate for the uniform connector height, achieving the required tilt angle without requiring differently dimensioned connectors throughout the entire structure.
2Manufacturing precision
If differently dimensioned connectors are used to achieve the desired tilt angle, then the tilt angle is achieved, but reliability decreases due to imperfections when forming connectors
Solution Approach 1:
The patent transitions from varying connector dimensions to varying pad surface sizes, eliminating the reliability issues associated with forming connectors of different dimensions. The uniform connector geometry ensures consistent material properties and bonding characteristics, while the pad size variations achieve the tilt angle without compromising connector reliability.
3Device complexity
If a single type of connection elements is used, then device complexity is reduced, but achieving the desired tilt angle becomes more difficult
Solution Approach 1:
The patent maintains uniform connection elements while achieving tilt angle precision through local variations in pad surface sizes. This approach simplifies the overall device by using a single connector type, while the locally varied pad geometries provide the necessary precision for achieving the desired tilt angle.
Solution Approach 2:
The patent shifts the degree of freedom for achieving tilt angle from the vertical dimension (connector height) to the lateral dimension (pad surface area). This dimensional transition allows uniform connectors to be used while still achieving precise tilt angle control through pad geometry variations.
4Manufacturing precision
If connection elements distribute across pads of varying sizes, then tilt angle is achieved, but the distribution process becomes more complex
Solution Approach 1:
The patent employs self-service by allowing the connection elements to naturally distribute across pads of varying sizes during the reflow process. The varying pad areas automatically guide the connector distribution and orientation, achieving the desired tilt angle through self-organization rather than requiring complex external control mechanisms.
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 approach simplifies the fabrication process, enhances reliability by maintaining a consistent tilt angle, and effectively prevents back reflection in VCSELs, while allowing for efficient optical coupling within the desired angle range.
Implementation Method 1
In particular, in a reflow process during the manufacturing, the connection elements distribute across the surface of the bonding pads such that a varying vertical extent of the connection elements is achieved
Data Source
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AI summary
A bonded structure (1) comprises a substrate component (20) having a plurality of first pads (21) arranged on or within a surface (22) of the substrate component (20), and an integrated circuit component (10) having a plurality of second pads (11) arranged on or within a surface (12) of the integrated circuit component (10). The bonded structure (1) further comprises a plurality of connection elements (31) physically connecting the first pads (21) to the second pads (11). The surface (12) of the integrated circuit component (10) is tilted obliquely to the surface (22) of the substrate component (22) at a tilt angle (α) that results from nominal variations of surface sizes of the first and second pads (21, 11) .