RDL Device Orientation and Width Variation for Thermal Stress Management
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Solution Overview
Problem
In semiconductor package manufacturing, the delamination of devices in the redistribution layer (RDL) due to thermal stress occurs because of differing thermal expansion coefficients between the encapsulant and the RDL components.
Innovation Solution
The chip package structure is designed with a high stress region and a low stress region, where devices in the RDL are oriented parallel to the stress direction and have a greater width in the low stress region to prevent delamination, and the devices in the high stress region are disposed with first portions parallel to the stress direction and second portions with increased width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If devices in the RDL are made of different materials to achieve diverse functions, then device functionality is improved, but thermal expansion coefficient differences cause delamination during thermal processes
Solution Approach 1:
The patent applies local quality by creating distinct high stress and low stress regions within the RDL structure. Devices are strategically placed in low stress regions, and stress relief structures are introduced at specific locations to locally manage thermal stress concentrations, thereby preventing delamination while maintaining material diversity for functional requirements
Solution Approach 2:
The patent introduces stress relief structures as intermediary elements between devices with different thermal expansion coefficients. These intermediate structures act as buffers that accommodate differential thermal expansion, reducing stress transmission to device interfaces and preventing delamination during thermal processing
2Ease of manufacture
If the RDL structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but stress distribution cannot be effectively managed leading to device delamination
Solution Approach 1:
The patent segments the RDL into functionally distinct regions: high stress regions, low stress regions, and stress relief zones. This segmentation allows each region to be optimized for its specific purpose while maintaining overall structural integrity and manageable manufacturing processes through standardized region definitions
3Area of stationary object
If devices are oriented perpendicular to stress direction to maximize space utilization, then area efficiency is improved, but delamination occurs due to stress concentration
Solution Approach 1:
The patent employs asymmetric device orientation strategies where devices in high stress regions are positioned at specific angles relative to stress directions, while devices in low stress regions can be oriented for optimal space utilization. This asymmetric approach balances stress management requirements with area efficiency considerations
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 design stabilizes the devices in the RDL, preventing delamination during thermal processes by managing stress distribution effectively.
Implementation Method 1
the encapsulant and devices (e.g., a wire, a conductive via and so on) in the RDL, due to being made of different materials, have different thermal expansion coefficients, and thus, a delamination phenomenon occurs to the devices in the RDL due to the affection of a stress during a subsequent thermal process
Data Source
AI summary
A chip package structure including a substrate, a redistribution layer (RDL), a chip and an encapsulant is provided. The RDL is disposed on the substrate. The chip is disposed on the RDL and is electrically connected with the RDL. The encapsulant is disposed on the RDL and encapsulates the chip. The chip is located in the high stress region. From a top view, the chip is located in the high stress region, and the low stress region surrounds the high stress region. The RDL includes at least one first device located in the high stress region. From the top view, the extending direction of the at least one first device is parallel to a stress direction at a position thereof.