Semiconductor Package Insulation Layer for Creepage Distance
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Solution Overview
Problem
High power semiconductor packages face challenges in heat management and safety due to heat generation, requiring effective cooling and compliance with industry safety and isolation specifications, such as UL Standards, which existing technologies have not adequately addressed.
Innovation Solution
A semiconductor package design featuring a base, die, lead, connector, mold compound, and an electrical insulation layer with a fixed thickness to ensure minimum spacing and meet isolation requirements, along with a clip to press against the substrate, providing guaranteed electrical insulation and heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling measures such as heat sinks are provided for high power semiconductor packages, then heat management is improved, but the package must meet minimum creepage distance, clearance distance, and isolation distance requirements between high voltage and low voltage/ground potential, which increases device complexity and reduces ease of manufacture
Solution Approach 1:
An electrical insulation layer is introduced as an intermediary component between the connector (carrying high voltage) and the heat sink (at ground potential). This insulation layer with fixed thickness provides the required creepage and clearance distances, allowing the heat sink to be positioned closer to the semiconductor device while maintaining safety isolation requirements.
Solution Approach 2:
The insulation requirement is satisfied by utilizing the vertical dimension (thickness of insulation layer) rather than increasing horizontal spacing. By placing the insulation layer between the connector apex and the heat sink mounting surface, the design meets isolation requirements without increasing the overall footprint or complicating the package structure.
2Temperature
If sufficient cooling is provided through heat sink to ensure normal operation, then temperature control is improved, but the package structure becomes more complex to meet safety and isolation requirements
Solution Approach 1:
The insulation layer has a fixed, defined thickness that is controlled within tight tolerances. This parameter control allows the heat sink to be positioned at a predetermined distance from the connector apex, simplifying the manufacturing process by providing clear dimensional specifications for assembly while ensuring compliance with safety isolation requirements.
3Reliability
If minimum spacing is ensured between connector apex and heat sink to meet isolation requirements, then safety compliance is improved, but the spacing between connector and heat sink increases, reducing compactness
Solution Approach 1:
A thin film insulation layer is used to provide the required electrical isolation. This thin film approach maintains compact spacing between the connector and heat sink while ensuring minimum spacing requirements are met, as the insulation is provided in the vertical dimension rather than requiring increased horizontal separation.
Data Source
AI summary
A semiconductor package includes a base, a die attached to the base, a lead and a connector electrically connecting the lead to the die. A mold compound encapsulates the die, the connector, at least part of the base, and part of the lead, so that the lead extends outward from the mold compound. An electrical insulation layer separate from the mold compound is attached to a surface of the mold compound over the connector. The electrical insulation layer has a fixed, defined thickness so that the package has a guaranteed minimum spacing between an apex of the connector and a surface of the electrical insulation layer facing away from the connector.