Sacrificial Cap Packaging for Wafer Optical Access
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Solution Overview
Problem
Maintaining optical pathways through integrated circuit architectures is challenging, particularly in manufacturing and implementation, especially for chiplets with optical elements used in artificial intelligence and machine learning functions, due to difficulties in preserving access to optical components during the overmolding process.
Innovation Solution
The use of a sacrificial cap with a recess is applied over the optical region before overmolding, followed by a grinding process to expose an optical window, ensuring access to optical components while maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an overmold is applied to protect mechanical components, then mechanical integrity is improved, but optical access to components is blocked
Solution Approach 1:
The cap is divided into a first portion that covers the optical component and a second portion that extends beyond it, creating distinct functional zones. This segmentation allows the overmold to be applied selectively - covering mechanical components for protection while leaving the optical component accessible through the first portion's opening.
Solution Approach 2:
Different portions of the cap have different properties: the first portion is designed with an opening for optical access, while the second portion provides extended mechanical coverage. This local differentiation enables simultaneous achievement of optical accessibility and mechanical protection in different areas of the package.
2Use of energy by moving object
If optical components are exposed for access, then optical transmission is improved, but mechanical protection is reduced
Solution Approach 1:
The cap structure segments the protection function: the first portion provides minimal coverage to maintain optical access, while the second portion extends coverage for mechanical protection. This allows the package to achieve both optical transmission and mechanical protection, with the overmold further enhancing protection for covered areas.
Solution Approach 2:
The cap extends in multiple dimensions - the first portion covers the optical component in the primary plane, while the second portion extends beyond it in the lateral dimension. This dimensional extension allows the optical component to remain accessible while other areas gain mechanical protection.
3Ease of operation
If a sacrificial cap is used to preserve optical access, then optical component accessibility is improved, but manufacturing complexity increases
Solution Approach 1:
The cap is placed on the substrate before the overmold is applied. This preliminary action serves as a template or mask that defines where the overmold should and should not be applied, simplifying the subsequent overmolding process rather than complicating it.
Solution Approach 2:
The sacrificial cap acts as an intermediary element during manufacturing. It temporarily occupies space and guides the overmold application, then is removed to reveal the final structure with proper optical access. This intermediary approach simplifies the overall manufacturing process by providing a clear template for overmold deposition.
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 cap in conjunction with a unique overmolding process.