Multi-layer bus bar unit production via electrodeposition coating
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Solution Overview
Problem
Conventional multi-layer bus bar units require new molds for different specifications, leading to increased production costs and time to market, and are prone to defects like weld lines, shorts, and voids, which affect long-term reliability due to stress and thermal history.
Innovation Solution
A method involving electrodeposition coating of metal bus bars with heat-resistant materials like polyimide or polyamidimide, followed by controlled heating and pressure treatments to form resin covering layers that bond the bus bars together, reducing the need for multiple molds and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insert injection molding is used to cover bus bars with resin molded parts, then the bus bars are covered and insulated, but new molds need to be designed and manufactured for different specifications, increasing production costs and time to market
Solution Approach 1:
The patent extracts the resin coating process from the injection molding process. Instead of using complex injection molds to apply resin, the bus bars are coated with resin in a separate, simpler process, and then assembled using a standard press die. This separates the coating function from the molding function, eliminating the need for complex injection molds while maintaining insulation and coverage.
Solution Approach 2:
The patent introduces a universal press die that can be used for assembling different multi-layer bus bar units with various specifications. This single press die replaces the need for multiple specialized injection molds, allowing the same tooling to accommodate different bus bar configurations through adjustable fixtures and positioning mechanisms.
2Productivity
If the interval between bus bars is reduced to decrease assembly thickness and increase capacitance, then compactness and electrical performance improve, but weld lines, shorts, and voids occur during injection molding, leading to poor pressure resistance
Solution Approach 1:
The patent applies preliminary coating to the bus bars before assembly. The resin coating is applied to the bus bar surfaces in advance, creating a protective layer that prevents defects during assembly. This preliminary coating ensures that when bus bars are placed close together, the resin layers bond properly without creating voids or shorts, maintaining both compactness and manufacturing precision.
Solution Approach 2:
The resin coating acts as an intermediary layer between adjacent bus bars. This intermediate resin layer fills gaps and prevents direct metal-to-metal contact, eliminating shorts and weld lines while maintaining the reduced interval between bus bars. The intermediary resin ensures proper bonding and pressure resistance even when bus bars are closely spaced.
3Reliability
If conventional injection molding is used to assemble multi-layer bus bars, then bus bars are covered with resin, but separation occurs between bus bars and resin under stress and thermal history, deteriorating long-term reliability
Solution Approach 1:
The patent changes the parameters of the resin application process by using coating methods (such as dip coating, spray coating, or roller coating) instead of injection molding. This allows for controlled resin thickness and better adhesion to the bus bar surfaces. The coating process parameters (viscosity, coating speed, drying temperature) are optimized to ensure strong bonding that withstands stress and thermal history over long periods.
Solution Approach 2:
The patent uses composite material structures where resin-coated bus bars are assembled into multi-layer configurations. The resin coating forms a strong composite interface between the metal bus bars and the insulating resin material. This composite structure, with properly bonded interfaces, resists separation under operational stress and thermal cycling, ensuring long-term reliability.
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 method allows for rapid adaptation to different specifications with reduced production costs and minimizes defects, ensuring long-term electrical and mechanical reliability by using a single press die and high-strength resin covering layers.
Implementation Method 1
depositing a coating film over an entire surface of each of the plurality of bus bars by electrodeposition coating with an electrodeposition coating material having heat resistance and insulation properties
Implementation Method 2
subjecting a coating film of a predetermined bus bar among the plurality of bus bars with the coating films to a heating treatment, so that the coating film of the predetermined bus bar is completely cured
Implementation Method 3
obtaining the multi-layer structure by alternately overlapping, and then subjecting to a pressure and heating treatment, the bus bar having the completely-cured coating film and the bus bar having the semi-cured coating film, so that the semi-cured coating film is completely cured and the plurality of bus bars adhere to each other by the completely-cured coating film
Data Source
AI summary
A method for producing a multi-layer bus bar unit includes preparing a plurality of metal flat plate-shaped bus bars, each with electrode terminal parts at two or more locations, depositing a coating film over an entire surface of each bus bar by electrodeposition coating, subjecting a coating film of a predetermined bus bar to a heating treatment so that the coating film is completely cured, subjecting another bus bar to a heat treatment so that the bus bar is semi-cured, and obtaining a multi-layer structure by alternately overlapping, and then subjecting to a pressure and heating treatment, the bus bar with the completely-cured coating film and the bus bar with the semi-cured coating film, so that the semi-cured coating film is completely cured and the plurality of bus bars adhere to each other by the completely-cured coating film.