Base Plate Grooves for Insulating Grease Containment
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Solution Overview
Problem
The alternating heat generation and cooling in semiconductor devices cause thermal expansion and contraction of the base plate, leading to the grease applied between the base plate and the cooling fin to stick out, resulting in a decrease in the amount of insulating grease and deteriorating cooling performance over time.
Innovation Solution
The semiconductor device incorporates grooves on the lower surface of the base plate, specifically designed to surround semiconductor elements, which maintain a constant amount of insulating grease by allowing it to expand and contract within these grooves, preventing grease overflow and ensuring stable cooling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base plate is fixed to the cooling fin using grease and screws, then the cooling fin and grease conform to each other through pressurization, but the grease spreads in the surface direction of the base plate during fixing
Solution Approach 1:
The base plate is segmented into multiple regions by grooves that divide the grease retention area into separate zones. Each groove creates an independent containment region, preventing grease from spreading across the entire surface while maintaining localized grease quantity for reliable fixing.
Solution Approach 2:
The grooves create localized regions with different grease retention properties. The groove portions provide enhanced grease containment in specific areas where needed, while other areas maintain standard grease distribution, optimizing both fixing reliability and grease quantity management.
2Productivity
If the base plate undergoes thermal expansion and contraction due to alternating heat generation and cooling, then the semiconductor element can operate, but the grease gradually sticks out of the edge of the base plate
Solution Approach 1:
The grooves are pre-formed on the base plate before assembly, creating predetermined grease containment structures. This preliminary action ensures that grease is confined to specific regions from the outset, preventing thermal expansion from causing grease to migrate to the edges during operation.
Solution Approach 2:
The grooves alter the physical parameters of the grease containment environment by creating defined boundaries with specific depths and widths. These parameter changes restrict grease movement even when thermal expansion occurs, maintaining consistent grease quantity between the base plate and cooling fin.
3Reliability
If grooves are provided on the base plate to prevent grease infiltration into screw holes, then grease containment is improved, but the grooves may cause grease to stick out at the edges due to thermal expansion
Solution Approach 1:
The grooves are strategically positioned and dimensioned to create localized containment zones that direct grease inward toward the center of the base plate. This local quality design ensures grease is contained near the screw holes without creating pressure points that would force grease outward at the edges during thermal expansion.
Solution Approach 2:
The grooves act as intermediary structures between the grease and the screw holes, providing a controlled path for grease containment. By serving as a mediator, the grooves prevent direct grease infiltration into screw holes while also managing grease distribution to prevent edge overflow during thermal cycles.
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 grooves effectively keep a consistent amount of insulating grease between the base plate and the cooling fin, maintaining stable cooling performance even with repeated thermal expansion and contraction, thus preventing deterioration of cooling efficiency.
Implementation Method 1
the base plate expands, while when power is off, its temperature decreases, causing the base plate to contract
Implementation Method 2
when power is off, its temperature decreases, causing the base plate to contract
Implementation Method 3
a grease diffusion preventing portion is provided on at least one of opposing surfaces of the base plate and the cooling fin to avoid the grease from infiltrating into screw holes
Data Source
AI summary
A semiconductor device (10) includes a metallic base plate (22) provided with an upper surface (22a) and a lower surface (22b), a plurality of insulating substrates (24) provided on the upper surface (22a), and a plurality of semiconductor elements (26) and (28) mounted side by side on the respective insulating substrates (24). Annular grooves (50) and (52) for storing insulating grease are provided on the lower surface (22b) of the base plate (22). A surface (40a) of a cooling fin (40) is superimposed on the lower surface (22b) with insulating grease (42) interposed therebetween and insides of the annular grooves (50) and (52) are filled with the insulating grease (42).