Semiconductor Package Coating for Higher Creepage Distance
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Solution Overview
Problem
Existing methods for improving creepage distance in semiconductor packages for high voltage applications either increase package size, require additional assembly steps, or compromise thermal properties, making them unsuitable for miniaturization and high power applications.
Innovation Solution
Applying a coating with higher electrical volume resistivity than the package's insulating material over parts of the package to increase the creepage distance without modifying the package design or reducing thermal conductivity, using materials like Al2O3/TiO2, parylene, or polyimide with high Comparative Tracking Index (CTI) values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between conductors is increased to improve creepage properties, then creepage distance is improved, but package size increases
Solution Approach 1:
The patent applies a coating with higher electrical volume resistivity than the base insulating material at specific locations where creepage improvement is needed. This creates local enhancement of insulating properties without requiring global increase in conductor spacing, thus improving creepage distance while maintaining compact package dimensions.
Solution Approach 2:
The patent uses a composite structure consisting of base insulating material combined with a coating layer of different material having superior electrical volume resistivity. This composite approach allows the package to achieve enhanced creepage properties through the combination of materials rather than increasing physical dimensions.
2Reliability
If plastics are added over exposed conductive parts to improve creepage, then creepage properties are improved, but assembly complexity increases
Solution Approach 1:
The patent integrates the creepage improvement function directly into the package structure by applying a coating during the manufacturing process. This merges the insulating enhancement with the package fabrication itself, eliminating the need for separate assembly steps where additional plastics would be added after package assembly, thus reducing overall assembly complexity.
Solution Approach 2:
The coating is applied to the insulating material during package manufacturing before the package is assembled with conductive elements. This preliminary action ensures creepage protection is built-in from the start, avoiding subsequent assembly steps that would be required if plastics were added after package assembly.
3Reliability
If leadframe package designs are used to improve creepage, then creepage properties are improved, but heatsink size is reduced
Solution Approach 1:
The patent applies the high resistivity coating selectively to specific regions of the insulating material where creepage enhancement is required, rather than using leadframe designs that would globally reduce heatsink size. This localized approach preserves the full heatsink structure and its thermal properties while achieving creepage improvement only where electrically necessary.
Solution Approach 2:
The patent employs a composite material solution (base insulating material plus high resistivity coating) that provides creepage enhancement without the structural changes required by leadframe designs. This allows the package to maintain its original heatsink architecture and thermal performance while achieving the desired electrical insulation properties.
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
Enhances creepage properties while maintaining thermal resistance within acceptable limits, ensuring safety and reliability for high voltage applications without increasing package size or reducing heat dissipation capabilities.
Implementation Method 1
applying a coating over at least part of said insulating material of said package, wherein said coating has an electrical volume resistivity higher than an electrical volume resistivity of said insulating material of said package to increase the initial creepage distance and improve package creepage of the semiconductor package
Data Source
AI summary
The present disclosure relates to a method of improving semiconductor package creepage, the package includes a semiconductor device, and a plurality of electrically conductive contacts at a surface of the package, the package includes insulating material for electrically insulating the package between the plurality of electrically conductive contacts, an initial creepage distance is defined by the shortest distance over the surface of the package between two of the plurality of contacts, and the method includes the steps of applying a coating over at least part of the insulating material of the package, and the coating has an electrical volume resistivity higher than an electrical volume resistivity of the insulating material of the package to increase the initial creepage distance and improve package creepage of the semiconductor package.