Power Semiconductor Substrate Insulation Compound Reduction
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Solution Overview
Problem
A significant portion of the insulation compound used in power semiconductor modules is unnecessary, as it is used primarily for homogeneous filling rather than effective insulation, posing a waste and inefficiency in the internal insulation process.
Innovation Solution
A method involving a substrate with an insulation layer and a metal layer forming conductor tracks, coated with a viscous dielectric insulation compound using casting processes, where the compound is initiated to cross-link partially to allow excess to drip off, reducing the amount of compound used while ensuring adequate insulation of components, including bond connections, and acting as an adhesive for the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is completely immersed in the insulation compound to ensure homogeneous filling, then the electrical insulation is improved, but the amount of insulation compound used increases significantly
Solution Approach 1:
The patent applies partial immersion instead of complete immersion of the substrate in the insulation compound. The substrate is immersed only to a specific level (e.g., 50-80% of substrate height) rather than fully, which reduces the quantity of insulation compound used while still providing adequate electrical insulation for the critical components and conductor tracks.
Solution Approach 2:
The patent implements selective insulation by applying insulation compound only to specific regions where electrical insulation is critical. The insulation is concentrated around conductor tracks, bond connections, and power semiconductor components rather than uniformly filling the entire housing, optimizing the distribution of insulation material.
2Quantity of substance
If excess insulation compound is allowed to drip off the substrate, then the amount of insulation compound used is reduced, but the homogeneous filling is compromised
Solution Approach 1:
The patent intentionally allows partial excess insulation compound to drip off the substrate after immersion. This controlled dripping removes unnecessary insulation material from non-critical areas while maintaining adequate insulation coverage on the substrate surface, achieving both reduction in material usage and sufficient insulation performance.
3Reliability
If the insulation compound is fully cross-linked before placing the substrate in the housing, then the insulation properties are optimized, but the adhesive bonding between substrate and housing is reduced
Solution Approach 1:
The patent performs preliminary partial cross-linking of the insulation compound before final housing assembly, but leaves it in a semi-cured state. This preliminary action provides initial insulation properties while maintaining the compound's adhesive characteristics, enabling strong bonding between the substrate and housing cap when assembled.
Solution Approach 2:
The patent exploits the dynamic state of the insulation compound during the manufacturing process. The compound transitions from liquid (for immersion and adhesion) to partially cross-linked (for insulation and structural stability) to fully cross-linked (for final insulation properties). This dynamic control allows optimization of both adhesive bonding and insulation properties at different stages.
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 method reduces the amount of insulation compound used by at least half without compromising electrical properties, ensuring thorough insulation and adhesion between the substrate and housing, thereby optimizing the internal insulation of power semiconductor modules.
Implementation Method 1
insulation compounds whose cross-linking is initiated by the action of ultraviolet light or heat are used
Implementation Method 2
insulation compounds whose cross-linking is initiated by the action of ultraviolet light or heat are used
Implementation Method 3
the insulation compound not yet completely cross-linked, it advantageously also acts as an adhesive and causes an adhesive bond between the housing and the substrate
Implementation Method 4
it is preferred to use casting processes, since in such processes the insulation compound securely fills even regions covered, for instance, with bond wires
Data Source
AI summary
A method for internal electrical insulation of a substrate for a power semiconductor module having a framelike insulating housing with a cap and having an insulating substrate. The substrate has conductor tracks and power semiconductor components mounted thereon. The power semiconductor components are connected to connection elements, e.g., further conductor tracks or power semiconductor components, by means of bond connections. The method is characterized by the following steps: a) forming the substrate; b) coating the substrate with a viscous dielectric insulation compound in a casting process or immersion process; c) initiating the cross-linking of the insulation compound; d) with the substrate in a suspended position, permitting excess insulation compound to drip off, and securely enveloping the bond connections with insulation compound; and e) placing the substrate in the housing.