Shielded Dielectric Layer for Electronic Assemblies
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Solution Overview
Problem
Larger packaged electronic devices face thermal stress issues due to variations in underfill dielectric layers, leading to electrical performance de-tuning and potential failure of electrical conductors in electronic assemblies.
Innovation Solution
A shielding dielectric layer is introduced between the packaged electronic device and the PCB, which extends across the package surface and de-sensitizes the device to variations in the underfill dielectric layer's electrical properties, creating a controlled electrical environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an underfill dielectric layer is utilized to support thermal stresses, then the durability of the electronic assembly is improved, but the electrical performance of receive and transmit channels is de-tuned
Solution Approach 1:
A shielding dielectric layer is introduced as an intermediary between the packaged electronic device and the underfill dielectric layer. This shielding layer has a dielectric constant matched to the package substrate, creating a controlled electrical environment that blocks the de-tuning effect of the underfill layer while allowing it to provide mechanical support for thermal stress relief
Solution Approach 2:
The shielding dielectric layer is positioned specifically adjacent to the package substrate where electrical performance is critical, rather than uniformly throughout the entire assembly. This localized approach maintains electrical performance in the critical region while allowing the underfill layer to provide durability benefits in other areas
2Strength
If the dielectric constant of the underfill layer is varied, then different mechanical properties are achieved, but the electrical performance becomes unpredictable
Solution Approach 1:
The shielding dielectric layer acts as a buffer that decouples the electrical performance from variations in the underfill layer's dielectric constant. By matching the dielectric constant to the package substrate, it creates a consistent electrical reference that isolates sensitive electrical channels from mechanical underfill variations
Solution Approach 2:
The dielectric constant of the shielding layer is specifically selected to match the package substrate, creating a controlled electrical parameter in the critical region. This parameter matching ensures predictable electrical performance regardless of what dielectric constant is used in the underfill layer for mechanical optimization
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 shielding dielectric layer significantly reduces the impact of underfill dielectric layer variations on the electronic assembly's performance, enhancing durability and signal integrity by minimizing reflection coefficient changes across different dielectric constants.
Implementation Method 1
a shielding dielectric layer that extends across a package surface of the packaged electronic device. The shielding dielectric layer functions to de-sensitize the packaged electronic device to variations in the composition, electrical properties, or dielectric constant of the underfill dielectric layer
Data Source
AI summary
Shielded and packaged electronic devices, electronic assemblies, and methods are disclosed herein. The shielded and packaged electronic devices include a packaged electronic device with a package surface and a plurality of electrically conductive package pads arranged on the package surface, a shielding dielectric layer extending in contact with the package surface and having a shielding layer surface and a plurality of openings that extends between the shielding layer surface and the plurality of electrically conductive package pads, and a plurality of electrical conductors that extends from the plurality of electrically conductive package pads and projects from the shielding layer surface. The electronic assemblies include a printed circuit board with a board surface and a plurality of electrically conductive board pads arranged on the board surface, the shielded and packaged electronic device, and an underfill dielectric layer. The methods include methods of manufacturing the electronic assemblies.