Wafer Level Semiconductor Package Dual Shielding Layers EMI Isolation
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Solution Overview
Problem
Current semiconductor packaging solutions, such as shielding or insulating films in leaded or ball grid array packages, provide only partial electromagnetic interference (EMI) isolation, which is inadequate for wafer level packages (WLP) and flip chip packages containing RF and baseband circuits, especially as these packages demand higher integration and efficiency.
Innovation Solution
A wafer level semiconductor package design featuring a substrate with a first and second shielding layer applied to opposite surfaces, mounting RF and baseband modules with solder bumps, and covering these modules with the shielding layers to substantially isolate the baseband module from EMI generated by the RF module, while also serving as a heat sink for improved thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shielding or insulating film is used in leaded or ball grid array packages, then electromagnetic interference isolation is improved, but the shielding is only partial and effectiveness is limited
Solution Approach 1:
The shielding structure is divided into multiple segments: a first shielding layer on the front surface, a second shielding layer on the back surface, and intermediate shielding structures. This segmented approach creates comprehensive EMI isolation that prevents electromagnetic interference from RF circuits from affecting baseband circuits, resolving the limitation of partial shielding in prior art.
Solution Approach 2:
The patent implements nested shielding layers where the first shielding layer on the front surface, the second shielding layer on the back surface, and intermediate shielding structures are positioned at different depths and levels within the package. This nested configuration creates multiple barriers against EMI, significantly enhancing shielding effectiveness compared to single-layer approaches.
2Area of stationary object
If wafer level packages and flip chip packages are used for higher circuit integration, then space efficiency and electrical performance are improved, but practical EMI solutions are limited due to unique layout and structure
Solution Approach 1:
The patent applies shielding layers with specific properties at different locations within the WLP structure. The first shielding layer is positioned near RF circuits on the front surface, the second shielding layer is positioned near baseband circuits on the back surface, and intermediate shielding structures are strategically placed. This localized shielding approach provides targeted EMI protection while maintaining the compact WLP form factor.
Solution Approach 2:
The patent extends EMI protection into the vertical dimension by implementing multiple shielding layers at different depths within the package structure. The front surface shielding layer, intermediate shielding structures, and back surface shielding layer create a three-dimensional shielding network that effectively blocks EMI paths while maintaining the thin profile characteristic of WLP packages.
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 solution effectively isolates baseband modules from RF-generated EMI and enhances thermal performance by using shielding layers that absorb and reflect incident electromagnetic interference, providing comprehensive EMI shielding and improved circuit performance in WLP and flip chip packages.
Implementation Method 1
The first and second shielding layers substantially cover the wafer level semiconductor package to isolate the baseband module from electromagnetic interference generated by the RF module
Implementation Method 2
The first and second shielding layers substantially cover the wafer level semiconductor package to isolate the baseband module from electromagnetic interference generated by the RF module
Implementation Method 3
The first and second shielding layers substantially cover the wafer level semiconductor package to isolate the baseband module from electromagnetic interference generated by the RF module, while also serving as a heat sink for improved thermal performance
Data Source
AI summary
A wafer level semiconductor package has a substrate and an RF module and baseband module coupled to the substrate with solder bumps. An underfill material is disposed under the RF module and baseband module. A first shielding layer is applied to a first surface of the substrate. A seed layer is deposited on the substrate and RF module and baseband module. A second shielding layer is plated over the seed layer, except over the contact pads on the substrate. The second shielding layer can be made from copper, gold, nickel, or aluminum. The first and second shielding layers substantially cover the wafer level semiconductor package to isolate the baseband module from electromagnetic interference generated by the RF module. The first and second shielding layers are grounded through the substrate.