Semiconductor Die Stress Buffering for Drift-Resistant Packaging
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Solution Overview
Problem
Semiconductor devices, particularly Hall sensors and high precision voltage reference circuits, are susceptible to performance drift due to mechanical stress, which affects their sensitivity and accuracy.
Innovation Solution
Incorporating a stress absorbing material between the semiconductor die and the package molding material, using a containment structure with peripheral walls to define a cavity filled with a deformable material like silicone, which acts as a mechanical buffer to reduce stress transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the semiconductor die is directly molded in the package, then the manufacturing process is simple, but mechanical stress is transmitted to the piezoresistive elements causing performance drift
Solution Approach 1:
A stress-absorbing material layer is introduced as an intermediary between the semiconductor die and the package molding material. This intermediate layer absorbs mechanical stress before it reaches the piezoresistive elements, preventing performance drift while maintaining manufacturing simplicity.
Solution Approach 2:
The stress-absorbing material is placed beforehand between the die and the molding material to cushion against upcoming mechanical stress. This preemptive cushioning protects the piezoresistive elements from stress-induced performance degradation before the stress can affect them.
2Reliability
If stress absorbing material is added between the die and package, then performance immunity against mechanical stress is improved, but device complexity increases
Solution Approach 1:
The package structure is segmented into distinct functional layers: the semiconductor die, the stress-absorbing material layer, and the package molding material. This segmentation allows each layer to perform its specific function independently, with the intermediate layer dedicated to stress absorption.
Solution Approach 2:
The package employs composite material construction by combining the semiconductor die with a stress-absorbing material layer that has different mechanical properties. This composite structure leverages the complementary characteristics of each material to achieve both structural integrity and stress 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 approach significantly reduces the performance drift caused by mechanical stress, achieving a reduction of over 40% in sensitivity shifts, thereby enhancing the immunity of semiconductor devices to mechanical stress.
Implementation Method 1
stress absorbing material intermediate at least one selected portion of said front surface of the at least one semiconductor die and the package molding material
Implementation Method 2
stress absorbing material intermediate at least one selected portion of said front surface of the at least one semiconductor die and the package molding material
Data Source
AI summary
A leadframe includes a die pad and a set of electrically conductive leads. A semiconductor die, having a front surface and a back surface opposed to the front surface, is arranged on the die pad with the front surface facing away from the die pad. The semiconductor die is electrically coupled to the electrically conductive leads. A package molding material is molded over the semiconductor die arranged on the die pad. A stress absorbing material contained within a cavity delimited by a peripheral wall on the front surface of the semiconductor die is positioned intermediate at least one selected portion of the front surface of the semiconductor die and the package molding material.