Semiconductor Module Fin Base Structure for Insulation Integrity
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Solution Overview
Problem
The heat sink integrated power module experiences warping due to mold resin shrinkage, leading to potential separation or cracking of the insulating sheet, which deteriorates the insulation properties.
Innovation Solution
A semiconductor module design featuring a fin base with rising wall portions and swaging portions, including contact and spaced-apart portions, to reduce bending stress and ensure proper swaging of fins, thereby maintaining insulation integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the mold resin is used to seal the fin base, lead frame, insulating sheet, and power semiconductor element, then the components are protected and held together, but heat shrinkage of the mold resin causes warping that leads to separation or cracking of the insulating sheet
Solution Approach 1:
The second surface of the fin base is divided into multiple regions: a swaging portion with a groove for fin attachment, and multiple rising wall portions that extend in the first direction. This segmentation distributes the stress from mold resin shrinkage across different regions, preventing concentration of bending stress at any single point and thereby preventing insulating sheet separation or cracking.
Solution Approach 2:
The rising wall portions are strategically positioned to provide localized structural support in regions where bending stress occurs during fin swaging. These rising walls create rigid zones that counteract the warping tendency caused by mold resin heat shrinkage, while the swaging portion maintains its flexibility for fin attachment. This local reinforcement prevents insulating sheet failure without compromising the overall sealing function.
2Manufacturing precision
If a jig is inserted into the swaging groove to plastically deform the swaging portion and expand the groove width, then the fins are swaged properly, but bending stress causes separation between the frame pattern and insulating sheet or cracks in the insulating sheet
Solution Approach 1:
The rising wall portions are pre-formed on the fin base before the fin swaging operation. These rising walls are prepared in advance to provide the necessary structural support during the subsequent jig insertion and plastic deformation process. By having this support structure ready beforehand, the bending stress that would otherwise cause insulating sheet separation or cracking is prevented during the fin swaging operation.
3Strength
If the swaging portion is plastically deformed to swage the fins, then the fins are securely attached, but the bending stress from flattening the warp compromises the insulation property
Solution Approach 1:
The rising wall portions create localized rigid zones that counteract bending stress during fin swaging, while the swaging portion maintains its flexibility for secure fin attachment. This local reinforcement strategy ensures that the insulating sheet is protected from cracking in the support regions while allowing the necessary plastic deformation in the swaging region to achieve strong fin attachment.
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 design effectively suppresses insulation property deterioration by reducing bending stress and ensuring sufficient fixing force during the swaging process, preventing separation or cracking of the insulating sheet.
Implementation Method 1
Due to heat shrinkage of the mold resin, the heat sink integrated power module described in PTL 1 may be warped convexly along a direction from the first surface toward the second surface
Implementation Method 2
When a jig is inserted into the swaging groove, the swaging portion is plastically deformed and a width of the swaging groove is expanded along the second direction
Data Source
AI summary
A semiconductor module includes: a fin base including a first surface and a second surface, the second surface being a surface opposite to the first surface; an insulating sheet arranged on the first surface; a plurality of frame patterns arranged on the first surface with the insulating sheet interposed therebetween; a semiconductor element arranged on at least one of the plurality of frame patterns; and a plurality of fins swaged onto the second surface so as to be spaced apart from each other in a first direction.