Integrated Fuse for Semiconductor Package Overcurrent Protection
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Solution Overview
Problem
Existing semiconductor device packaging solutions with discrete fuses are bulky, increase complexity, and raise costs due to the need for additional space and increased package complexity, especially in power and load driving applications where overcurrent protection is required.
Innovation Solution
Incorporating a fuse with a fuse element mounted on a lead within the semiconductor device package, where the fuse element is sized to carry normal current but melts and opens when excess current is detected, protecting external circuitry, and is formed contemporaneously with packaging processes using existing wire or ribbon bonding techniques, thus reducing the need for external components and simplifying board design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete fuses are used for overcurrent protection, then reliable protection is achieved, but board area increases and device complexity increases
Solution Approach 1:
The fuse is merged with the semiconductor device package by mounting the fuse directly to a lead within the package. The fuse element is electrically connected in series with the semiconductor die through bond wires, integrating the protection function into the existing package structure rather than using a separate discrete component.
Solution Approach 2:
The lead serves multiple functions: it provides electrical connection for the semiconductor device and simultaneously serves as a mounting substrate for the fuse. This multi-functionality eliminates the need for separate mounting space for the fuse on the system board.
2Reliability
If discrete fuses are mounted to packaged devices, then overcurrent protection is achieved, but package complexity and cost increase
Solution Approach 1:
The fuse mounting is merged with the semiconductor device packaging process. The fuse is mounted to a lead within the package during the same packaging operations used for the semiconductor die, eliminating separate mounting steps and reducing package complexity.
Solution Approach 2:
The existing package leads and bonding infrastructure serve dual purposes: they provide electrical connections for the semiconductor device and simultaneously provide the mounting and electrical connection infrastructure for the fuse, eliminating the need for additional external mounting hardware.
3Ease of manufacture
If fuse element is exposed to mold compound, then packaging process is simplified, but fuse reliability decreases due to potential contamination
Solution Approach 1:
The fuse element is extracted from the mold compound environment by mounting it to the lead, which positions it outside the region that would be encapsulated by mold compound. This isolation prevents potential contamination while still allowing the fuse to be packaged concurrently with the semiconductor device.
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 solution provides reliable overcurrent protection within the package, reducing board area requirements and simplifying design while maintaining compatibility with existing packaging processes, thereby lowering costs and enhancing fuse reliability by isolating the fuse element from mold compound.
Implementation Method 1
the fuse element is sized to carry normal current but melts and opens when excess current is detected
Implementation Method 2
the fuse element is sized to carry normal current but melts and opens when excess current is detected
Data Source
AI summary
In a described example, an apparatus includes: a package substrate having a die pad configured for mounting a semiconductor die, and leads spaced from the die pad; a semiconductor die mounted on the die pad; a fuse mounted to a lead, the fuse having a fuse element coupled between a fuse cap and the lead, the fuse having a fuse body with an opening surrounding the fuse element, the fuse cap attached to the fuse body; electrical connections coupling the semiconductor die to the fuse; and mold compound covering the semiconductor die, the fuse, the electrical connections, and a portion of the package substrate, with portions of the leads exposed from the mold compound to form terminals.