Electronic Packaging Structure With Mechanical Support Layers
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Solution Overview
Problem
The internal silicon chip at the POP upper packaging layer fractures and fails due to concentrated mechanical and thermal stresses, particularly when subjected to mechanical loads and cyclic temperature loads, as existing underfill materials do not adequately distribute stress across the packaging layers.
Innovation Solution
Incorporating mechanical support layers with dummy solder balls or epoxy mold compounds between packaging layers to distribute deformation and reduce stress concentrations, thereby enhancing the structural integrity and reliability of the packaging structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low-viscosity underfill without filler is used to improve filling speed and reworkability, then the underfill can be easily dispensed and reworked, but the underfill overflows from the edge of dispensed glue to local areas between the POP lower layer and upper packaging layer, causing concentrated stress and chip fracture
Solution Approach 1:
The patent applies local quality by using different viscosity underfill materials in different regions: low-viscosity underfill is used in the first area (peripheral region) to ensure easy filling and reworkability, while high-viscosity underfill is used in the second area (central region) to prevent overflow and reduce stress concentration. This spatial differentiation of material properties resolves the contradiction between ease of operation and reliability.
2Reliability
If underfill is used to distribute mechanical stress and thermal stress evenly across solder joints, then overall reliability of the POP is improved, but stress concentration occurs at the edge position of overflowing glue under mechanical load, causing silicon chip fracture
Solution Approach 1:
The patent differentiates the underfill material properties by region: the first area (peripheral region) uses low-viscosity underfill for stress distribution, while the second area (central region) uses high-viscosity underfill to prevent overflow and eliminate stress concentration points. This resolves the contradiction by ensuring uniform stress distribution without creating new stress concentration zones.
Solution Approach 2:
The patent uses a composite underfill structure combining two underfill materials with different viscosity characteristics. The low-viscosity underfill provides good flow and stress distribution, while the high-viscosity underfill provides structural support and prevents overflow. This composite approach allows the system to achieve both overall reliability improvement and stress concentration prevention.
Data Source
AI summary
A high-reliability electronic packaging structure includes a plurality of packaging layers and mechanical support layers. An electrically functional solder joint is provided in a first area of each of the packaging layers, and any two adjacent packaging layers are coupled using electrically functional solder joints. A mechanical support layer is disposed in a second area of each of the packaging layers, and the mechanical support layer is configured to support the two adjacent packaging layers. The first area is provided on a periphery of the second area. Hence, a problem that an internal silicon chip at an upper packaging layer or a lower packaging layer fractures and fails when the upper packaging layer or the lower packaging layer is subject to a mechanical load can be resolved.