Stacked Glass Package Substrates for Thermal Stress Relief
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Solution Overview
Problem
Glass core substrates for integrated circuits face challenges due to their brittle nature, leading to potential cracks and failures known as seware failures, which are exacerbated by thermal expansion mismatches between glass and other materials in the package substrate, resulting in mechanical stress and reduced reliability.
Innovation Solution
Implementing a substrate core with multiple distinct glass cores stacked on top of each other, each with tailored thermal expansion coefficients (CTEs) to create a gradual CTE gradient, reducing stress and using buffer materials to absorb thermal fluctuations, and incorporating metal slugs for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass core substrates are used to provide higher plated through-hole density and lower signal losses, then signal integrity and manufacturing precision are improved, but the brittle nature of glass leads to increased mechanical stress and seware failures
Solution Approach 1:
The glass core substrate is divided into multiple glass layers with different coefficients of thermal expansion (CTE). Each layer has a tailored CTE value that creates a gradient from the top to bottom surface, allowing differential thermal expansion that reduces mechanical stress and prevents seware failures while maintaining high plated through-hole density
Solution Approach 2:
The coefficient of thermal expansion (CTE) parameter is varied across different glass layers. The first glass layer has a first CTE value, the second glass layer has a second CTE value different from the first, creating a CTE gradient that accommodates thermal expansion mismatches and reduces stress concentration in the brittle glass material
2Stability of the object's composition
If glass core substrates are used to achieve lower total thickness variation, then stability of the object's composition is improved, but thermal expansion mismatches between glass and other materials increase mechanical stress
Solution Approach 1:
Different regions of the substrate (top and bottom surfaces) are assigned different glass layers with locally optimized CTE values. The first glass layer near the top surface has a CTE tailored to match materials in that region, while the second glass layer near the bottom surface has a different CTE matched to materials in that region, reducing local thermal stress while maintaining overall thickness stability
Solution Approach 2:
The substrate employs a composite structure with multiple glass layers of different compositions and CTE values. This composite approach allows each layer to be optimized for its specific thermal environment while collectively providing thickness stability and reduced mechanical stress through the CTE gradient
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 minimizes seware failures by reducing thermal stress and enhancing mechanical support, while maintaining high plated through-hole density and signal integrity, thus improving the reliability and performance of the package substrate.
Implementation Method 1
each with tailored thermal expansion coefficients (CTEs) to create a gradual CTE gradient, reducing stress and using buffer materials to absorb thermal fluctuations
Implementation Method 2
incorporating metal slugs for heat dissipation
Data Source
AI summary
Systems, apparatus, articles of manufacture, and methods for package substrates with stacks of glass layers having different coefficients of thermal expansion are disclosed. An example package substrate includes: a first glass layer including a first through glass via extending therethrough, the first glass layer having a first coefficient of thermal expansion (CTE); and a second glass layer including a second through glass via extending therethrough, the second glass layer having a second CTE different from the first CTE, the first through glass via electrically coupled to the second through glass via.