Semiconductor Module Bonding With 5°C Cooling Gradient Control
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Solution Overview
Problem
The existing techniques for manufacturing semiconductor devices face challenges in reducing stress on the insulating layer during the bonding of a semiconductor module and a metal base plate, particularly when using a ceramic insulating substrate, and in controlling the peeling of the resin insulating layer due to thermal expansion differences.
Innovation Solution
A method involving the use of a semiconductor module with a first metal plate, a resin or ceramic insulating layer, and a second metal plate, where the module is bonded to a metal base plate using a second bonding member with a lower melting point than the first, and precise temperature control is applied during cooling to maintain a temperature difference of 5° C. or less between the upper and lower surfaces, utilizing tin solder containing bismuth to minimize stress and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the copper plate is increased to improve rigidity, then the peeling of the resin insulating layer is suppressed, but the manufacturing cost increases
Solution Approach 1:
The invention changes the material parameter from copper to aluminum for the heat spreader, which has sufficient rigidity despite lower cost. This material substitution resolves the contradiction between achieving adequate rigidity and controlling manufacturing costs.
2Ease of manufacture
If a rolled copper plate is adopted instead of electrolytic copper foil to reduce cost, then the manufacturing cost decreases, but the adhesion to the resin insulating layer becomes lower
Solution Approach 1:
The invention introduces a resin insulating layer as an intermediary between the aluminum heat spreader and the ceramic insulating substrate. This intermediary layer provides the necessary adhesion and stress absorption, resolving the contradiction between cost reduction and adhesion maintenance.
Solution Approach 2:
The invention creates a composite structure consisting of aluminum heat spreader, resin insulating layer, and ceramic insulating substrate. This composite approach combines the advantages of each material while mitigating their individual disadvantages, achieving both cost reduction and adequate adhesion.
3Strength
If the rigidity of the metal plate is improved to suppress peeling, then the peeling resistance increases, but the stress on the ceramic insulating substrate increases
Solution Approach 1:
The invention changes the material parameter from copper to aluminum with controlled thickness (0.3-0.7mm), achieving sufficient rigidity for peeling resistance while limiting stress transmission to the ceramic substrate through optimized dimensional parameters.
Solution Approach 2:
The invention applies different material properties at different locations: the aluminum heat spreader provides rigidity where needed for peeling resistance, while the resin insulating layer provides stress absorption and cushioning where stress concentration occurs, creating a locally optimized stress distribution.
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
This approach effectively reduces stress on the insulating layer, prevents peeling, and enhances the durability of the semiconductor device's cooling/heating cycle, thereby improving its long-term reliability without increasing the rigidity of the metal plates.
Implementation Method 1
heating the metal base plate, the second bonding member, and the semiconductor module to melt the second bonding member
Implementation Method 2
cooling the metal base plate, the second bonding member, and the semiconductor module to cure the second bonding member
Implementation Method 3
During the cooling of the metal base plate, the second bonding member, and the semiconductor module, a difference between an upper surface temperature of the metal base plate and a lower surface temperature of the first metal plate at a solid phase line of the second bonding member is 5° C. or less
Data Source
AI summary
A method of manufacturing a semiconductor device includes a transfer molding step and a mold package mounting step. The mold package mounting step includes steps of disposing a semiconductor module on an upper surface of a metal base plate with a second bonding member therebetween, heating the metal base plate, the second bonding member, and the semiconductor module to melt the second bonding member, and then cooling the metal base plate, the second bonding member, and the semiconductor module to cure the second bonding member. During the cooling of the metal base plate, the second bonding member, and the semiconductor module, a difference between an upper surface temperature of the metal base plate and a lower surface temperature of a first metal plate at a solid phase line of the second bonding member is 5° C. or less.