Rotary Device Brush Bonding with Intermetallic Compound
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Solution Overview
Problem
Existing rotary devices that convert electric energy into rotational energy or vice versa face thermal damage issues due to high-temperature soldering or brazing, which can cause deformation or brittleness in adjacent members and lead to short circuits from excessive solder.
Innovation Solution
A rotary device using a conductive bonding material composed of an intermetallic compound produced by reaction between Sn or its alloys and CuNi, CuMn, AgPd, or CuCr alloys, which has a higher melting point than traditional high-temperature solders, reducing thermal damage and preventing short circuits by bonding at temperatures below 300°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature soldering or brazing is used to bond the brush to the supporting portion, then bonding strength is improved, but thermal damage occurs to adjacent members causing deformation or brittleness
Solution Approach 1:
The invention changes the temperature parameter of the bonding process by using a low-melting-point solder (melting point 183°C or lower) instead of traditional high-temperature soldering or brazing. This parameter change allows bonding to occur at temperatures below 300°C, preventing thermal damage to adjacent members while maintaining adequate bonding strength for the application.
2Strength
If high-temperature soldering is used, then bonding strength is improved, but excessive melted solder forms balls that fall on coils causing short circuits
Solution Approach 1:
The invention changes the melting point parameter of the solder to 183°C or lower, which is sufficiently low to prevent excessive solder from forming balls and falling on coils. The low melting point ensures controlled solder flow during bonding while eliminating the reliability issue of solder balls causing short circuits.
3Strength
If high-temperature soldering is used, then bonding strength is improved, but environmental load increases due to Pb-base solders
Solution Approach 1:
The invention changes the chemical composition parameter of the solder by using a low-melting-point solder that is free from lead (Pb) and other harmful substances. This compositional change reduces environmental load while maintaining bonding functionality, complying with environmental regulations.
4Strength
If brazing is used to bond the commutator to the coil, then bonding strength is improved, but the adjacent member becomes deformed or brittle
Solution Approach 1:
The invention changes the temperature parameter by replacing brazing with low-temperature soldering (melting point 183°C or lower). This temperature reduction prevents the adjacent member from becoming deformed or brittle while achieving sufficient bonding strength for the commutator-coil connection.
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 use of intermetallic compounds with higher melting points than traditional high-temperature solders minimizes thermal damage to adjacent members, enhances bonding strength, and reduces the environmental impact of lead-based solders while preventing short circuits through effective heat dissipation.
Implementation Method 1
a conductive bonding material including an intermetallic compound produced by reaction between first metal which is Sn or an alloy including Sn and second metal which is a CuNi alloy, a CuMn alloy, an AgPd alloy, a CuAl alloy, or a CuCr alloy, wherein the conductive bonding material bonds together the first piece and the second piece
Implementation Method 2
the intermetallic compound is produced under a reaction temperature below 300° C., or below the soldering temperature of a high-temperature solder, and has a higher melting point than the high-temperature solder (183° C. to 240° C.)
Data Source
AI summary
A rotary device having a brush that includes a slide-contact portion, a fixing section, and a conductive bonding material. The conductive bonding material bonds together the slide-contact portion and the fixing section. The conductive bonding material is composed of an intermetallic compound phase that is an alloy containing one of (1) at least two selected from a first group consisting of Sn, Cu and Ni, and (2) at least two selected from a second group consisting of Sn, Cu, and Mn.