Dual-Material Capacitor Case for Heat Dissipation and Insulation
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Solution Overview
Problem
Existing capacitors face issues with heat dissipation, as plastic cases fail to discharge heat effectively, leading to increased internal temperatures, and metal cases, while improving heat dissipation, are heavy and costly, with poor adhesion and separation problems in metal-plastic assemblies, especially when attached to IGBT units.
Innovation Solution
A capacitor with an insert injection metal-plastic dual-material case that integrates a metal case for improved heat dissipation and thermal conductivity, using a plastic material for insulation and a metallic external wall with a gel or fluid filler to create a dual-material structure, eliminating the need for thermal pads and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic case is used for the capacitor, then the material cost is reduced and insulation is maintained, but heat dissipation performance deteriorates and internal temperature increases
Solution Approach 1:
The patent applies a composite material structure where a metal case (aluminum or aluminum alloy) is formed on the outer surface of the plastic case through electroplating or electroless plating. This composite structure combines the insulation and cost benefits of plastic with the heat dissipation advantages of metal, resolving the contradiction between material cost and heat dissipation performance.
2Temperature
If a metal case is used for the capacitor, then heat dissipation performance is improved, but weight increases and material cost increases
Solution Approach 1:
The patent uses a composite case structure where a thin metal layer (5-50 μm) is deposited on the plastic case. This thin metal coating provides sufficient heat dissipation performance while keeping the overall weight much lower than a solid metal case, thus resolving the contradiction between heat dissipation and weight.
Solution Approach 2:
The metal coating is applied selectively to the outer surface of the plastic case, particularly in areas requiring heat dissipation. This localized application provides heat dissipation functionality without the full weight penalty of a complete metal case construction.
3Temperature
If a metal plate is attached to a plastic case using adhesion or insert injection, then heat dissipation is improved, but adhesion reliability deteriorates and separation occurs
Solution Approach 1:
The patent integrates the metal case directly into the plastic case through electroplating or electroless plating, creating a bonded composite structure. This eliminates the need for separate adhesion or insert injection processes, thereby avoiding adhesion failure and separation issues while maintaining heat dissipation performance.
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 solution enhances heat dissipation performance, maintains insulation, and reduces manufacturing costs by directly contacting the IGBT cooling unit, while preventing breakage and improving rigidity, with a reduced temperature rise and lower material costs compared to all-metal or all-plastic capacitors.
Implementation Method 1
a filler (40) permeating in a gel or fluid state into the space between the capacitor module and inner walls of the plastic case (20), and then hardened therein
Implementation Method 2
metal cases that discharge heat well have been developed and used
Data Source
AI summary
A capacitor includes a capacitor module including a capacitor device, a first busbar electrically connected with a thermally-sprayed surface of the capacitor device and having a first lead terminal on an exposed side, a second busbar electrically connected with the other thermally-sprayed surface of the capacitor device and having a second lead terminal on an exposed side, and an insulating sheet disposed between the first busbar and the second busbar to insulate an overlap region; a plastic case having a 3D space formed by four sides and a bottom to accommodate the capacitor module and having an open top; a metallic external wall is formed outside one side of the four sides or the bottom of the plastic case; and a filler permeating in a gel or fluid state into the space between the capacitor module and inner walls of the plastic case.