Moisture Protection Encapsulation for Packaged Electronic Circuits
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Solution Overview
Problem
Packaged electronic circuits, such as MMIC amplifiers, are prone to humidity-induced failures due to moisture ingress, which can lead to chemical reactions and device degradation, especially when operated at elevated temperatures and in high humidity environments, causing reliability issues and potential device failure.
Innovation Solution
The implementation of a moisture encapsulation method involving a protective dielectric layer, such as silicon oxide or silicon nitride, and a protective polymer layer, like polyimide, formed at specific temperatures to prevent out-gassing and create a barrier against moisture ingress, with the polymer layer covering pinholes and cracks in the dielectric layer to prevent ion penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective dielectric layer is formed on the integrated circuit chip, then moisture barrier protection is improved, but pinholes and cracks in the dielectric layer can still allow moisture ingress
Solution Approach 1:
A polymer encapsulation layer is formed over the dielectric layer to provide flexible moisture barrier protection. The polymer layer conformally coats the surface including pinholes and cracks in the dielectric layer, creating an additional protective film that blocks moisture ingress paths that the rigid dielectric layer cannot seal.
Solution Approach 2:
The encapsulation structure combines a dielectric material layer (such as silicon oxide or silicon nitride) with a polymer material layer. This composite structure leverages the advantages of both materials: the dielectric layer provides baseline protection and electrical isolation, while the polymer layer provides flexible conformal coverage that seals defects in the dielectric layer, together creating a superior moisture barrier.
2Reliability
If the polymer layer is formed at high temperature to improve adhesion and barrier properties, then protection effectiveness is improved, but out-gassing from the polymer layer can occur causing pinholes and reduced reliability
Solution Approach 1:
The formation temperature of the polymer encapsulation layer is carefully controlled and optimized. The temperature is maintained below the out-gassing threshold of the polymer material (typically below 200°C) to prevent decomposition and pinhole formation, while still achieving sufficient adhesion to the dielectric layer and adequate barrier properties against moisture ingress.
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 encapsulation method significantly reduces the likelihood of humidity-induced failures by creating a robust moisture barrier, enhancing the reliability of packaged electronic circuits, particularly in humid environments, and preventing chemical reactions that can lead to device failure.
Implementation Method 1
formed at specific temperatures to prevent out-gassing and create a barrier against moisture ingress
Implementation Method 2
creating a robust moisture barrier, enhancing the reliability of packaged electronic circuits, particularly in humid environments, and preventing chemical reactions that can lead to device failure
Data Source
AI summary
A packaged electronic circuit includes a substrate having an upper surface, a first metal layer on the upper surface of the substrate, a first polymer layer on the first metal layer opposite the substrate, a second metal layer on the first polymer layer opposite the first metal layer, a dielectric layer on the first polymer layer and at least a portion of the second metal layer and a second polymer layer on the dielectric layer.