Wafer Package Overmolding With Sacrificial Die Optical Access
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Solution Overview
Problem
Maintaining optical pathways through integrated circuit hardware during manufacturing and implementation is challenging, particularly for IC architectures with optical elements, as overmolding can obscure access to optical regions.
Innovation Solution
The use of a sacrificial die is employed to create an optical window by pre-cutting and removing a portion of the die before overmolding, ensuring access to optical regions like grating couplers through a void in the overmold layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If overmolding is applied to protect and encapsulate circuit package components, then mechanical protection and structural integrity are improved, but optical access to regions like grating couplers is blocked
Solution Approach 1:
The overmold is segmented into different regions: a first overmold region that covers and protects the circuit package components, and a second overmold region that is removed to create an optical window. This segmentation allows the overmold to provide mechanical protection where needed while leaving optical regions accessible.
Solution Approach 2:
A portion of the overmold is extracted or removed to form an optical window through which optical signals can pass. This extraction creates a clear path from the optical component on the circuit package to external optical fibers, maintaining both protection and access.
2Productivity
If the entire wafer surface is covered with overmold for manufacturing efficiency, then productivity and protection are improved, but access to optical regions for coupling is lost
Solution Approach 1:
The overmolding process is segmented to cover only the non-optical portions of the wafer surface, while leaving optical regions exposed or creating controlled access points. This allows efficient manufacturing through selective overmolding rather than complete coverage.
Solution Approach 2:
Different regions of the wafer receive different treatments: electrical components are covered with overmold for protection, while optical regions are left exposed or provided with specific access windows. This local differentiation maintains manufacturing efficiency while ensuring optical access where required.
3Ease of operation
If optical regions are left exposed on the wafer surface, then optical access is maintained, but mechanical protection and structural integrity are reduced
Solution Approach 1:
The overmold structure is segmented to provide coverage over the circuit package substrate and electrical components while intentionally leaving optical coupling regions accessible. This creates a protective enclosure that preserves mechanical strength while maintaining optical pathways.
Solution Approach 2:
The overmold acts as an intermediary structure that provides mechanical protection to the circuit package while incorporating optical windows that allow optical signals to pass through. This mediator structure reconciles the need for both protection and optical access.
Data Source
AI summary
The present disclosure relates to packaging techniques in connection with packaging electrical and optical components within circuit packages. For example, one or more examples described herein involve techniques for packaging an electro-photonic circuit while preserving access to a grating coupler, which may involve using a sacrificial die in conjunction with a unique overmolding process.