Completely Encapsulated Optical Multi-Chip Packages for Moisture Protection
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Solution Overview
Problem
Existing optical connectors in multi-chip packages face issues such as incomplete encapsulation leading to reliability concerns, incompatibility with high-volume manufacturing, exposure to mechanical and thermal shock, uncontrolled flow of underfill and encapsulation materials, and large fiber shufflers occupying valuable space.
Innovation Solution
The implementation of fully encapsulated optical connectors using lids with sealants, micro channels for fluid control, and a reduced footprint fiber shuffler design, along with a molded fiber distribution housing to protect fibers and optimize assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical connectors are used to couple fibers to optics dies, then optical signal transmission is enabled, but incomplete encapsulation occurs allowing moisture ingress and ice formation
Solution Approach 1:
A lid is provided that covers and encapsulates the optical connectors, creating a sealed environment. The lid acts as a protective shell that prevents moisture and environmental contaminants from reaching the optical connectors and fibers, thereby eliminating the reliability issues caused by incomplete encapsulation.
Solution Approach 2:
The optical connectors are nested within a cavity formed by the integrated heat spreader and package substrate, and further enclosed by the lid. This nested structure provides multiple layers of protection and complete encapsulation, preventing moisture ingress while maintaining the functional integration of components.
2Ease of manufacture
If exposed optical fibers are used in optical connectors, then fiber coupling is simplified, but vulnerability to mechanical shock and thermal shock increases
Solution Approach 1:
The lid encapsulates the optical connectors and exposed optical fibers, providing a protective shell that shields the fibers from mechanical shock and thermal shock during handling and solder reflow processes. This maintains the simplicity of fiber coupling while adding robust protection.
3Measurement precision
If optical connectors are mounted using traditional tools, then fiber alignment is achieved, but multiple pick-up tool tips are required increasing device complexity
Solution Approach 1:
The lid serves as an intermediary component that integrates the alignment and mounting functions. By providing a pre-aligned structure with the optical connectors, the lid eliminates the need for multiple pick-up tool tips while maintaining precise fiber alignment, thereby reducing mounting tool complexity.
4Ease of manufacture
If underfill and encapsulation materials are dispensed on planar surfaces, then material application is simple, but uncontrolled flow and poor location precision occur
Solution Approach 1:
The lid provides a structured cavity with specific geometric features that locally control the flow and placement of underfill and encapsulation materials. The cavity walls and structures guide the materials to precise locations, ensuring controlled distribution while maintaining the simplicity of dispensing operations.
5Adaptability or versatility
If large external fiber shufflers are used for routing optical fibers, then fiber routing flexibility is achieved, but package footprint increases
Solution Approach 1:
The fiber shuffling function is integrated within the cavity structure formed by the integrated heat spreader, package substrate, and lid. This nested arrangement allows fiber routing flexibility to be achieved within the compact package volume, eliminating the need for large external fiber shufflers and reducing the overall package footprint.
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3~4A
AI summary
Embodiments disclosed herein include optical packages. In an embodiment, an optical package comprises a package substrate, where the package substrate comprises a recessed edge. In an embodiment, a compute die is on the package substrate, and an optics die on the package substrate and overhanging the recessed edge of the package substrate. In an embodiment, an integrated heat spreader (IHS) is over the compute die and the optics die. In an embodiment, a lid covers the recess in the package substrate