Current Sense Alloy in IC Packages for Stable Low-TCR Measurement
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Solution Overview
Problem
Current sense elements in electrical circuits often have high temperature coefficients of resistance, leading to inaccurate current measurements due to temperature variations and aging effects, which affect their reliability over time.
Innovation Solution
A semiconductor device with a current sense element made from alloys like copper, manganese, and nickel, which has a low temperature coefficient of resistance, minimizing resistance changes with temperature and mitigating aging issues through separate force and sense current paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional current sense element is used, then the device structure is simple, but the measurement precision deteriorates due to high temperature coefficient of resistance causing resistance changes with temperature variations
Solution Approach 1:
The patent uses a composite material structure consisting of a semiconductor die with specific alloy composition (copper, manganese, and nickel in controlled proportions) to create a current sense element with minimized temperature coefficient of resistance. This composite approach combines multiple elements to achieve superior temperature stability that single materials cannot provide alone
Solution Approach 2:
The patent separates the current sense element into distinct functional segments: the semiconductor die containing the sense element, the leadframe providing mechanical support and electrical connection, and the encapsulant protecting the assembly. This segmentation allows each component to be optimized independently for its specific function while maintaining overall system reliability
2Measurement precision
If a current sense element with high TCR is used, then the manufacturing process is simple, but the measurement precision deteriorates due to aging effects changing the resistance over time
Solution Approach 1:
The semiconductor die employs a composite alloy composition of copper, manganese, and nickel specifically engineered to resist aging effects. This material combination provides both low temperature coefficient of resistance and enhanced long-term stability, preventing resistance drift that would otherwise occur during the device service life
Solution Approach 2:
The patent carefully controls the compositional parameters of the alloy (specific ratios of copper, manganese, and nickel) to achieve optimal electrical properties. By adjusting these material parameters, the invention achieves a resistance characteristic that remains stable over both temperature variations and extended time periods
3Measurement precision
If a low temperature coefficient of resistance material is used, then the measurement precision is improved, but the manufacturing complexity increases due to specific material composition requirements
Solution Approach 1:
The patent specifies precise compositional parameters for the alloy (copper, manganese, and nickel in controlled proportions) to achieve the desired low temperature coefficient of resistance. These parameter specifications guide the manufacturing process to produce the required material properties through standard metallurgical techniques
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 semiconductor device provides accurate current measurements with less than 0.5% resistance change over a temperature range of 0°C to 150°C, maintaining reliability by using materials with a low temperature coefficient of resistance and avoiding aging-related errors.
Implementation Method 1
The current sense element has a temperature coefficient of resistance in the range of approximately −0.00004/° C. to approximately 0.00004/° C.
Implementation Method 2
Some current sense elements also change with age and thus a current sense element that is accurate at one point in time may not be accurate at a later point in time.
Data Source
AI summary
A semiconductor device includes a leadframe having a first level and a second level. The semiconductor device includes a semiconductor die and a conductive alloy. The conductive alloy is between the semiconductor die and the first level of the lead frame. The conductive alloy is configured to be a current sense element. The semiconductor device further includes a first conductive post coupling the semiconductor die to the conductive alloy, a second conductive post coupling the semiconductor die to the conductive alloy, and a third conductive post coupling the semiconductor die to the second level of the lead frame. The second conductive post is configured to be a first sense terminal. The third conductive post is configured to be a second sense terminal.