Conductive Heat Sink Package for Low-Resistance TVS Devices
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Solution Overview
Problem
Semiconductor devices, such as transient voltage suppression (TVS) protection devices, face limitations in heat dissipation and on-resistance due to the low heat capacity and conductivity of Quad Flat No-leads (QFN) packages, as well as asymmetrical heat diffusion and current crowding in existing package designs.
Innovation Solution
An electrically conductive heat sink is integrated onto a semiconductor substrate, allowing for both thermal and electrical conduction, which enhances heat dissipation and provides a compact package by mounting the substrate's active surface closest to the heat sink, reducing on-resistance and improving robustness during stress pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If QFN package is used, then small footprint and small package height are achieved, but heat dissipation capability deteriorates
Solution Approach 1:
The patent combines the electrical connection function and heat dissipation function into a single integrated substrate structure. The substrate serves dual purposes: providing electrical pathways for current flow and acting as a heat sink through its thermally conductive material composition, thereby resolving the contradiction between compact size and heat dissipation capability.
Solution Approach 2:
The substrate is constructed from composite materials with high thermal conductivity, such as metal substrates or ceramic materials, while maintaining electrical insulation properties. This allows the substrate to efficiently conduct heat away from the pn junction while providing electrical isolation between conductive elements, achieving both compact packaging and effective heat dissipation.
2Device complexity
If bond wire is used for electrical connection, then device assembly is simplified, but on-resistance increases
Solution Approach 1:
The patent removes the bond wire element from the device structure entirely. Instead of using separate bond wires to connect the pn junction to external contacts, the electrical connection is achieved through direct integration into the substrate, eliminating the additional resistance introduced by bond wires while maintaining assembly simplicity.
Solution Approach 2:
The electrical connection function previously performed by separate bond wires is merged into the substrate itself. The substrate provides continuous electrical pathways from the pn junction to external contacts, eliminating discontinuities and contact resistances associated with bond wire connections.
3Device complexity
If pn junction is located near one surface of substrate, then device structure is simplified, but heat diffusion becomes asymmetrical
Solution Approach 1:
The substrate uses high thermal conductivity materials that enable efficient heat diffusion in all directions, overcoming the asymmetry caused by the pn junction's surface location. The superior thermal properties of the composite substrate material ensure uniform heat distribution and dissipation regardless of the heat generation location within the device.
4Temperature
If clip bond is used instead of bond wire, then thermal capacity is improved, but thermal conduction is limited by multiple solder or glue points
Solution Approach 1:
The patent merges the electrical connection and thermal management functions into a single integrated substrate structure, eliminating the need for separate clip bonds and their associated multiple solder or glue points. This integration creates continuous thermal pathways without discontinuities, improving thermal conduction while maintaining adequate thermal capacity.
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 electrically conductive heat sink effectively dissipates heat generated during stress pulses, enabling the device to handle larger currents and reducing the risk of overheating, while also providing an electrical connection, thus enhancing the device's robustness and reducing package thickness.
Implementation Method 1
The first surface of the substrate is mounted on a first surface of the heat sink for electrical and thermal conduction between the heat sink and the substrate via the first contact
Implementation Method 2
The first surface of the substrate is mounted on a first surface of the heat sink for electrical and thermal conduction between the heat sink and the substrate via the first contact
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A semiconductor device and a method of making the same. The device includes an electrically conductive heat sink (8) having a first surface. The device also includes a semiconductor substrate (2). The device further includes a first contact (14) located on a first surface of the semiconductor substrate (2). The device also includes a second contact (16) located on a second surface of the semiconductor substrate (2). The first surface of the semiconductor substrate (2) is mounted on the first surface of the heat sink (8) for electrical and thermal conduction between the heat sink (8) and a substrate via the first contact (14). The second surface of the semiconductor substrate (2) is mountable on a surface of a carrier.