Semiconductor Package Stiffener Rib Layout for CTE Mismatch
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Solution Overview
Problem
The mismatched coefficient of thermal expansion (CTE) between semiconductor devices and lids in semiconductor packages leads to delamination of thermal interface materials and cracking of adhesives, causing structural instability and reliability issues.
Innovation Solution
Employing a stiffener structure with a stiffener ring and ribs made of materials like copper or stainless steel, which includes design features such as T-shaped or L-shaped cross-sections to enhance adhesion and mechanical strength, reducing warpage and improving thermal interface material bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a lid is attached to semiconductor devices using thermal interface material and adhesive, then heat dissipation is improved, but delamination and cracking occur due to CTE mismatch
Solution Approach 1:
The patent introduces a stiffener structure with specific geometric parameters (thickness, width, layout pattern) to modify the mechanical properties of the package. By changing the structural parameters of the package substrate, the overall CTE of the package is adjusted to better match the lid, reducing thermal expansion mismatch and preventing delamination while maintaining heat dissipation performance
Solution Approach 2:
The patent creates a composite structure by adding a stiffener layer (made of materials like copper, stainless steel, or ceramic) to the package substrate. This composite construction combines the thermal conductivity benefits of metal stiffeners with the insulating properties of the substrate, achieving both improved heat dissipation and reduced CTE mismatch through material composition
2Productivity
If semiconductor devices are mounted on packaging substrate, then device integration is improved, but warpage occurs due to CTE mismatch
Solution Approach 1:
The stiffener structure modifies the mechanical and thermal parameters of the package assembly. By strategically placing stiffeners with optimized dimensions and material properties, the package's resistance to warpage is enhanced, maintaining structural stability during thermal cycling while preserving device integration benefits
Solution Approach 2:
The stiffener structure is divided into multiple segments or ribs distributed across the package substrate. This segmentation allows localized compensation of thermal expansion stresses in different regions, preventing overall package warpage while maintaining device integration
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 stiffener structure enhances adhesion strength, reduces delamination and cracking, and compensates for CTE mismatch, thereby improving the structural integrity and thermal performance of semiconductor packages.
Implementation Method 1
The mismatched coefficient of thermal expansion (CTE) between semiconductor devices and lids in semiconductor packages leads to delamination of thermal interface materials and cracking of adhesives
Implementation Method 2
The stiffener structure enhances adhesion strength, reduces delamination and cracking, and compensates for CTE mismatch, thereby improving the structural integrity and thermal performance of semiconductor packages
Implementation Method 3
A lid is then attached to the semiconductor device for dissipating the heat generated during the operation; such attachment is through a thermal interface material (TIM) and/or an adhesive
Data Source
AI summary
A semiconductor package includes a first component, a second component, and a stiffener rib. The first component is disposed on a substrate. The second component is disposed aside the first component and on the substrate. The stiffener rib is disposed between the first component and the second component. The lid is attached to the stiffener rib, the first component and the second component. The lid includes a recess portion on the stiffener rib. A first sidewall and a second sidewall of the recess portion laterally surround the stiffener rib. A first top space between a first top sidewall of the stiffener rib and the first sidewall of the recess portion is greater than a second top space between a second top sidewall of the stiffener rib and the second sidewall of the recess portion.