SMD Package Top Side Cooling Creepage Length
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Solution Overview
Problem
Existing surface-mount device (SMD) packages with top side cooling (TSC) face challenges in ensuring adequate heat dissipation while meeting safety requirements for minimum clearance distance and creepage length, which can impact the reliability and efficiency of power semiconductor devices in automotive, consumer, and industrial applications.
Innovation Solution
The package design incorporates a lead frame structure with a top layer and structural features that increase the creepage length, allowing for effective heat dissipation through a heat dissipation device while maintaining safety by defining the electrical potential separation using the package body surface contour, and separating the package top side into sections to enhance thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat dissipation device is mounted on the package top side, then heat dissipation efficiency is improved, but the creepage length and clearance distance requirements may not be met
Solution Approach 1:
The package top side is divided into multiple vertical levels (first vertical level and second vertical level), creating a three-dimensional structure. The first outside terminal is positioned at the first vertical level while the top layer is positioned at the second vertical level, utilizing vertical space to achieve both heat dissipation and electrical isolation requirements simultaneously
Solution Approach 2:
The package top side surface is segmented into different vertical levels, with the first section at a higher level and the second section at a lower level. This segmentation allows the heat dissipation device to be mounted on the first section while maintaining adequate creepage length to the top layer on the second section
2Loss of energy
If the package top side is used for heat dissipation, then thermal management is improved, but the creepage length between terminals may be insufficient
Solution Approach 1:
The invention transitions from a two-dimensional planar arrangement to a three-dimensional vertical arrangement. By positioning terminals and layers at different vertical levels, the creepage length is extended through vertical separation while maintaining compact horizontal footprint, enabling effective thermal management without compromising electrical isolation
3Productivity
If the package footprint side is used for mounting, then surface-mount technology benefits are achieved, but heat dissipation capability is limited
Solution Approach 1:
The package design implements multi-functionality by utilizing both the footprint side for electrical mounting connections and the top side for heat dissipation. The footprint side maintains SMT compatibility with outside terminals for circuit board mounting, while the top side provides a separate heat dissipation surface, allowing the package to simultaneously fulfill electrical and thermal management functions
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 design enhances heat dissipation efficiency and ensures compliance with safety requirements, improving the reliability and performance of power semiconductor devices by increasing the creepage length and effectively managing thermal stress.
Implementation Method 1
heat can be removed away from the package that encloses the die
Implementation Method 2
heat dissipation device... remove heat away from the package body
Data Source
AI summary
A package encloses a power semiconductor die and has a package body with a package top side, package footprint side and package sidewalls. The die has first and second load terminals for blocking a blocking voltage. A lead frame structure electrically and mechanically couples the package to a support and includes an outside terminal extending out of the package footprint side and/or the sidewalls, and is electrically connected with the first load terminal. A top layer arranged at the package top side is electrically connected with the second load terminal. A creepage length between the electrical potential of the outside terminal and the electrical potential of the top layer is defined by a package body surface contour. The surface contour is formed at least by the package top side and package sidewall. At least one structural feature also forms the surface contour is configured to increase the creepage length.