Semiconductor Package Assembly With Silicate Insulation for Creepage
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Solution Overview
Problem
Existing semiconductor package assemblies for high voltage devices face challenges in maintaining adequate creepage and clearance distances while accommodating smaller package sizes and large heatsinks for thermal dissipation, leading to increased arcing and thermal build-up risks.
Innovation Solution
Incorporating a silicate containing mineral layer, such as mica, adjacent to the heat sink element and leads in the semiconductor package assembly to enhance creepage performance and provide superior electrical insulation, allowing for larger heatsinks and improved thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the creepage and clearance distances are increased to meet high voltage standards, then the electrical insulation and arcing resistance are improved, but the package assembly size increases
Solution Approach 1:
An adhesive tape is introduced as an intermediary component between the heat sink element and the molding resin. This tape provides additional creepage distance and electrical insulation without significantly increasing the overall package volume, as it utilizes the vertical space already allocated for the heat sink assembly.
Solution Approach 2:
The solution transitions from increasing horizontal creepage distances (which would increase package footprint) to adding vertical insulation layers. The adhesive tape is positioned in the vertical dimension between the heat sink and molding resin, providing the required creepage distance without expanding the package's planar dimensions.
2Temperature
If larger heat sink elements are used to improve thermal dissipation, then the thermal management performance is improved, but the arcing risk increases due to reduced clearance distances
Solution Approach 1:
The adhesive tape serves as a mediating layer between the heat sink element and the surrounding environment. It provides electrical insulation that prevents arcing while allowing the heat sink to maintain its large surface area for effective thermal dissipation.
Solution Approach 2:
The package assembly uses a composite structure combining the heat sink element with an adhesive tape layer that has both adhesive and insulating properties. This composite approach allows simultaneous achievement of thermal management and electrical insulation functions.
3Reliability
If the creepage distance is increased by adding insulation layers, then the electrical insulation is improved, but the package assembly complexity increases
Solution Approach 1:
The adhesive tape performs multiple functions simultaneously: it provides electrical insulation for creepage distance, serves as an adhesive bonding layer, and acts as a structural support element. This multi-functionality reduces the need for separate dedicated insulation components, thereby simplifying the overall assembly.
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 silicate mineral layer mitigates arcing risks and enhances design margins, enabling semiconductor packages with larger heatsinks and maintaining electrical insulation, thus addressing the limitations of smaller package sizes.
Implementation Method 1
the silicate containing mineral mounted on the lead frame and/or the semiconductor die structure adjacent to the heat sink element, shields the latter from the leads of the lead frame and provides an improved creepage performance
Implementation Method 2
providing an adhesive tape having an adhesive side and containing at least one layer comprised of the at least a silicate containing mineral on the adhesive side, and mounting at least the lead frame on the adhesive side of the adhesive tape
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
According to a first example of the disclosure, a method for manufacturing a semiconductor package assembly is proposed. The method comprising the steps of i) forming at least one semiconductor package by means of the sub-steps i1) providing a lead frame made from a metal material having a first frame side and a second frame side opposite to the first frame side as well as having at least two terminals; i2) providing at least one semiconductor die structure having a first die side and a second die side opposite to the first die side with its second die side on the first frame side of the lead frame; i3) electrically and mechanically attaching the at least one semiconductor die structure to the terminals of the lead frame; i4) attaching a heat sink element on the first die side and/or the second die side of the semiconductor die structure; and ii) encapsulating the at least one semiconductor die structure, the heat sink element and the plurality of terminals with a molding resin leaving at least a portion of the heat sink and at least a portion of the at least two terminals exposed. With the above steps at least one encapsulated semiconductor package assembly is formed. The method further comprises the step of iii) providing, at least prior to the encapsulating step ii), a layer comprised of at least a silicate containing mineral on the lead frame and/or the semiconductor die structure adjacent to the heat sink element.