Circuit Substrate With Variable-Width Electrode for Uniform Current Density
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Solution Overview
Problem
Existing circuit designs in power modules result in significant differences in circuit resistance and current density between parallel chips, leading to non-uniform temperature distribution and reduced service life.
Innovation Solution
A circuit substrate design featuring a second electrode with a varying cross-sectional width along its length, allowing for reduced circuit resistance and uniform current density by connecting parallel electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode outline is designed as a regular rectangle with parallel sides, then the manufacturing process is simple and easy to implement, but the circuit resistance difference between parallel chips becomes large (at least 11%), resulting in non-uniform current density and increased temperature difference
Solution Approach 1:
The patent applies asymmetry by designing the second electrode with a non-parallel configuration where the cross-sectional width varies along its length. Specifically, the first portion of the second electrode has a smaller cross-sectional width than the second portion, creating an asymmetric structure that compensates for the resistance differences in parallel chip connections. This asymmetric design ensures that chips closer to the first electrode experience lower resistance paths, while chips farther away experience higher resistance paths, thereby equalizing the current density across all parallel chips.
Solution Approach 2:
The patent implements local quality by varying the cross-sectional width of the second electrode at different positions along its length. The electrode is divided into a first portion with smaller width and a second portion with larger width. This local variation in geometric properties allows the electrode to provide different resistance characteristics at different locations, specifically reducing resistance for chips connected near the first portion and increasing resistance for chips connected near the second portion, thus achieving uniform current distribution across all parallel chips.
2Device complexity
If parallel chips are connected with equal-length electrodes, then the electrode structure is simple and symmetric, but the circuit resistance difference between first chip and last chip reaches at least 11%, causing non-uniform current density distribution
Solution Approach 1:
The patent breaks the symmetric electrode structure by designing the second electrode with non-uniform cross-sectional width. The first portion has a smaller width while the second portion has a larger width, creating an asymmetric configuration. This asymmetry is intentionally introduced to compensate for the position-dependent resistance differences in parallel chip connections, ensuring that the total resistance path from the first electrode through each parallel chip to the second electrode is equalized, thereby achieving uniform current density without requiring complex multi-electrode systems.
3Reliability
If the cross-sectional width of the first portion of the second electrode is increased from lower side to upper side, then the circuit resistance between electronic components is reduced and current density becomes uniform, but the electrode structure becomes more complex
Solution Approach 1:
The patent applies local quality by varying the cross-sectional width of the second electrode along its length. The first portion has a smaller cross-sectional width while the second portion has a larger cross-sectional width. This local variation in geometric properties creates position-dependent resistance characteristics that compensate for the different path lengths to parallel chips. The gradual increase in width from the first portion to the second portion provides a progressive resistance adjustment, ensuring uniform current density distribution and equalized resistance paths without requiring overly complex multi-segmented structures.
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 design effectively reduces circuit resistance and temperature differences between electronic components, enhancing the service life of the electronic device.
Implementation Method 1
the cross-sectional width of the first portion becomes larger from the lower side to the upper side... may effectively shorten the circuit resistance between the electronic components
Implementation Method 2
the difference between the circuit resistance of the first chip through which the current flows and the circuit resistance of the last chip through which the current flows is at least 11%. Due to the large difference in the circuit resistance between the chips, it is impossible to obtain a uniform current density and shorten the temperature difference between the chips
Data Source
AI summary
A circuit substrate includes a base material, a first electrode, and a second electrode. The base material has an upper side and a lower side opposite to each other in a length direction. The first electrode extends and is configured on the base material along the length direction. The second electrode is configured beside the first electrode and includes a first portion and a second portion connected to each other. The first portion is configured on the base material along the length direction. The second portion is configured on the base material along a width direction and is located between the upper side and the first electrode. A cross-sectional width of the first portion becomes larger from the lower side to the upper side.