Power Transistor Source Electrode Layout for Accurate Current Sensing
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Solution Overview
Problem
The reliability of semiconductor devices is compromised due to assembly variations causing misalignment and variability in the bonding of wires to the source electrode, leading to inaccurate current measurements and voltage drops, which affect the stability of the potential distribution and sense ratio.
Innovation Solution
The semiconductor device incorporates two detection points on the source electrode to sandwich the bonding point, ensuring stable potential measurement by averaging voltage readings, thereby reducing the impact of assembly variations and maintaining accurate current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wire is used to electrically connect the source electrode to the lead terminal, then the device complexity is reduced and ease of manufacture is improved, but assembly variations such as misalignment and variability in bonding area occur, leading to reduced measurement precision and reliability
Solution Approach 1:
The invention divides the detection function into multiple segments by providing both a first detection point and a second detection point on the source electrode. These multiple detection points are used to measure potentials at different locations, and through calculation, the current value is determined. This segmentation approach compensates for assembly variations by averaging out the effects of misalignment and bonding variability, thereby maintaining measurement precision while preserving ease of manufacture.
Solution Approach 2:
The invention implements a feedback mechanism where the control circuit measures potentials at multiple detection points, calculates the current based on these measurements, and uses this information to compensate for assembly variations. The control circuit adjusts measurements and calculations to account for the actual bonding conditions, ensuring accurate current measurement despite variations in wire bonding assembly.
2Measurement precision
If the detection point is positioned far from the bonding point to obtain a representative value, then the measurement covers a larger area, but voltage drop occurs due to increased distance, causing gradient in surface potential distribution and reduced measurement precision
Solution Approach 1:
The invention positions multiple detection points at different distances from the bonding point rather than using a single detection point far away. This segmentation of the measurement locations allows the system to capture potential distribution characteristics while minimizing the distance-related voltage drop that would occur with a single distant measurement point.
Solution Approach 2:
The invention uses the wire itself as an intermediary element with known resistance. By measuring potentials at multiple points along the source electrode and using the known wire resistance in calculations, the system can determine the actual current flowing through the wire while compensating for the voltage drop. The calculation process uses the potential difference measurements and wire resistance to derive accurate current values despite the presence of voltage drop.
3Reliability
If multiple detection points are added to compensate for assembly variations, then measurement precision and reliability are improved, but the device complexity increases
Solution Approach 1:
The invention adds multiple detection points to the source electrode to improve reliability by compensating for assembly variations. Each detection point provides additional measurement data that can be used to calculate the current value. The control circuit processes these multiple measurements through calculation to determine the final current value, which improves reliability while the segmented approach keeps the added complexity manageable.
Data Source
AI summary
A reliability of a semiconductor device can be improved by measuring a value of a current flowing through a power transistor accurately. A semiconductor chip includes a power transistor and a source electrode electrically connected to a source region of the power transistor. The source electrode and a lead terminal are electrically connected to each other via a wire. The source electrode includes detection points for detecting the value of the current flowing through the power transistor. The detection points are arranged so as to sandwich a bonding point of the wire bonded to the source electrode.