Embedded Flex Substrate Packaging With Exposed Trace Interconnects
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Solution Overview
Problem
Existing semiconductor device packages face challenges in accommodating sophisticated features while maintaining reliability, performance, and minimizing costs.
Innovation Solution
A semiconductor device with an embedded flex substrate that includes a semiconductor die mounted on a package substrate and a flex substrate sub-assembly with patterned flexible conductive traces, encapsulated with an encapsulant, allowing for flexible, high-density, and cost-effective 3D interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional semiconductor device packages are used, then manufacturing and assembly are simpler, but flexibility and density of interconnects are reduced
Solution Approach 1:
The patent transitions from planar 2D interconnect routing to three-dimensional routing by embedding flexible substrates vertically within the package. Conductive traces are routed through multiple layers and depths, allowing interconnects to extend in the Z-dimension (vertical axis) rather than only horizontally, thereby achieving higher flexibility and density without proportionally increasing footprint area.
Solution Approach 2:
The flexible substrate is embedded within the package structure, nesting the interconnect layer inside the encapsulant volume rather than placing it externally. This nested configuration allows the interconnects to be integrated within the existing package boundaries, achieving high flexibility while maintaining a compact overall form factor.
2Adaptability or versatility
If sophisticated features are added to semiconductor devices, then functionality is improved, but reliability and performance may deteriorate
Solution Approach 1:
The patent applies different material properties and structural characteristics to different regions of the package. The flexible substrate uses elastomeric materials with specific durometer ranges (e.g., 20-80 Shore A) in different zones to optimize local mechanical properties. Conductive traces are selectively placed and dimensioned in specific regions to provide appropriate electrical characteristics, while the encapsulant provides localized protection where needed. This localized optimization maintains reliability while enabling sophisticated features.
3Productivity
If higher density interconnects are implemented, then performance is improved, but manufacturing complexity increases
Solution Approach 1:
The flexible substrate with conductive traces is pre-formed and prepared separately before being embedded in the package. The elastomeric substrate is cured and conductive patterns are established in advance, allowing these components to be manufactured independently with optimized processes. This preliminary preparation simplifies the final assembly step while achieving high interconnect density, as the complex trace routing is already established in the pre-formed substrate rather than being created in-situ during package assembly.
Data Source
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AI summary
A method of forming a semiconductor device is provided. The method includes interconnecting a semiconductor die and a flex substrate sub-assembly with a package substrate. The flex substrate sub-assembly includes a flexible conductive trace. A first portion of the flexible conductive trace is conductively connected to the package substrate. The method further includes encapsulating with an encapsulant at least a portion of the semiconductor die and the flex sub-assembly. A second portion of the flexible conductive trace is exposed at a top surface of the encapsulant.