Wafer-Level Fan-Out Sealing Structure for Warpage and Solder Ball Stability
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Solution Overview
Problem
Conventional wafer level fan out semiconductor devices experience warpage and solder ball detachment due to thermal expansion and shrinkage, which affects their reliability and functionality.
Innovation Solution
The implementation of a wafer level fan out semiconductor device design where the first and second sealing parts have the same thermal expansion coefficient, minimizing warpage, and the solder balls are fixed and locked by the second sealing part to the redistribution layers, preventing detachment, while the second surface of the semiconductor die is exposed for enhanced heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wafer level fan out semiconductor device structure is used, then manufacturing is simplified, but warpage occurs due to thermal expansion mismatch
Solution Approach 1:
The patent changes the thermal expansion coefficient parameter of the sealing part to match that of the semiconductor die. By selecting a sealing part material with a thermal expansion coefficient within 10 ppm/°C of the semiconductor die, the invention resolves the warpage issue caused by thermal expansion mismatch while maintaining the simplified wafer-level manufacturing process
2Device complexity
If conventional sealing structure is used, then device assembly is simplified, but solder balls detach during thermal expansion or shrinkage
Solution Approach 1:
The patent modifies the mechanical parameter of the sealing part by selecting materials with matched thermal expansion coefficients. This parameter change ensures that the sealing part and semiconductor die expand and contract together during temperature cycles, preventing relative movement that would cause solder ball detachment while maintaining structural simplicity
Solution Approach 2:
The invention uses composite material selection where the sealing part is chosen from materials specifically matched to the semiconductor die's thermal expansion characteristics. This material matching creates a composite structure that moves uniformly under thermal stress, securing the solder balls without requiring additional complex anchoring mechanisms
3Temperature
If second surface of semiconductor die is exposed, then heat dissipation is enhanced, but device protection is reduced
Solution Approach 1:
The patent applies local quality by selectively exposing only the second surface of the semiconductor die for heat dissipation while keeping other surfaces protected. The sealing part provides localized protection on the exposed surface, allowing thermal management needs to be met without fully enclosing the device, thus balancing heat dissipation with environmental protection
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 effectively minimizes warpage and suppresses solder ball detachment, ensuring the reliability and performance of the semiconductor device by matching thermal expansion coefficients and securing solder balls, thereby enhancing heat dissipation efficiency.
Implementation Method 1
the first and second sealing parts have the same thermal expansion coefficient, minimizing warpage
Implementation Method 2
solder balls may be easily detached during thermal expansion or shrinkage
Implementation Method 3
the second surface of the semiconductor die is exposed for enhanced heat dissipation
Data Source
AI summary
A wafer level fan out semiconductor device and a manufacturing method thereof are provided. A first sealing part is formed on lateral surfaces of a semiconductor die. A plurality of redistribution layers are formed on surfaces of the semiconductor die and the first sealing part, and solder balls are attached to the redistribution layers. The solder balls are arrayed on the semiconductor die and the first sealing part. In addition, a second sealing part is formed on the semiconductor die, the first sealing part and lower portions of the solder balls. The solder balls are exposed to the outside through the second sealing part. Since the first sealing part and the second sealing part are formed of materials having thermal expansion coefficients which are the same as or similar to each other, warpage occurring to the wafer level fan out semiconductor device can be suppressed.