Hermetic Package with High Aspect Ratio Substrate
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Solution Overview
Problem
Hermetically sealed surface-mount packages face challenges in withstanding extreme conditions such as extreme temperatures and mechanical stress in applications like military, space, and downhole drilling, requiring enhanced protection and reliability while maintaining cost-effectiveness.
Innovation Solution
A hermetically sealed package design featuring an electrically insulating substrate with high flexural strength, thermally conductive tabs, and a lid, where the substrate has a high aspect ratio and metallization layers for a strong, reliable seal, and the tabs are joined to the substrate and lid using conductive materials with similar thermal expansion coefficients to minimize stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate has a high aspect ratio to reduce stress, then the package can withstand extreme conditions better, but the manufacturing precision required increases
Solution Approach 1:
The substrate aspect ratio is changed to a high value (greater than 10:1) to reduce thermal stress and improve reliability in extreme conditions. This parameter change allows the package to better withstand temperature transients and mechanical stress while maintaining manufacturability through controlled fabrication processes.
Solution Approach 2:
The package uses a composite structure combining an electrically insulating substrate with thermally conductive metallization layers and tabs. This composite approach allows the insulating substrate to provide electrical isolation while the conductive tabs manage thermal stress and provide mechanical strength, resolving the contradiction between reliability and manufacturing precision.
2Reliability
If thermally conductive tabs are used to reduce thermal stress, then the package reliability improves, but the device complexity increases
Solution Approach 1:
The metallization layers and tabs serve multiple functions simultaneously: they provide thermal conduction to manage heat, act as mechanical reinforcement to reduce thermal stress, and offer electrical connectivity. This multi-functionality improves reliability without proportionally increasing device complexity, as a single structural element performs multiple critical roles.
Solution Approach 2:
The package design incorporates tabs and metallization layers specifically to manage thermal expansion differences between materials. These elements accommodate dimensional changes during temperature transients, preventing stress concentration and improving reliability in extreme temperature environments.
3Reliability
If hermetic sealing is implemented to protect from environmental factors, then the semiconductor reliability improves, but the manufacturing cost increases
Solution Approach 1:
The hermetic sealing function is merged with the existing substrate and lid structure through integrated metallization layers that serve both as electrical/thermal conduits and as sealing elements. This consolidation eliminates the need for separate sealing components and processes, reducing manufacturing complexity and cost while maintaining hermetic protection.
Solution Approach 2:
The metallization layers on the substrate and lid self-form the hermetic seal through controlled bonding processes, without requiring additional sealing materials or complex assembly steps. The structural components themselves provide the sealing function, simplifying manufacturing and reducing costs.
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
The solution provides a robust, cost-effective hermetically sealed package that can withstand extreme conditions, ensuring reliable performance and efficient manufacturing with reduced thermal stress and defect formation, suitable for applications requiring high reliability.
Implementation Method 1
a plurality of electrically and thermally conductive tabs
Implementation Method 2
hermetically sealed surface mount packages are used to protect the semiconductor from such environmental factors
Data Source
AI summary
A hermetically sealed package has an electrically insulating substrate, a plurality of electrically and thermally conductive tabs, and a lid. The electrically insulating substrate has a plurality of apertures and an aspect ratio of about 10:1 or greater. The plurality of electrically and thermally conductive tabs is hermetically joined to a bottom surface of the electrically insulating substrate and at least one tab covers each of the apertures. The lid is hermetically joined to a top surface of the electrically insulating substrate proximate to a perimeter of the electrically insulating substrate.