Conductive Joint Article Using Oxide Glass Joining Layer
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Solution Overview
Problem
Conductive joint articles made from hard-to-solder metals like aluminum exhibit high electrical resistance when joined, inferior to those made from easy-to-solder metals like copper, due to low solder wettability and reliability issues.
Innovation Solution
A conductive joint article with a joining layer comprising an oxide glass phase containing vanadium, phosphorus, and barium, and a conductive metal phase, achieved through resistance welding with specific current density and pressure conditions, to reduce connection resistance below 1×10−5 Ω/mm2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If aluminum or aluminum alloy is used as electrode/wire material to reduce weight and cost, then weight and cost are reduced, but electrical conductivity and reliability of joining deteriorate due to low solder wettability
Solution Approach 1:
A joining material comprising a low-melting glass phase and electrical conductive particles is introduced as an intermediary between the aluminum electrode/wire and the joined metal. This joining material enables electrical conductive joining by facilitating metallurgical bonding while maintaining low connection resistance, thus resolving the reliability issue while preserving the weight reduction benefit of using aluminum
Solution Approach 2:
The invention changes the chemical composition parameters of the joining material by specifying that the low-melting glass phase contains specific metal elements (Cu, Ag, Ni, Zn, or In) at controlled concentrations. This parameter optimization enables the joining material to effectively remove oxide films from aluminum surfaces and form reliable electrical conductive joints, overcoming the inherent soldering difficulties of aluminum
2Ease of manufacture
If swage joining or ultrasonic joining is used for electrical conductive joining of aluminum, then joining can be performed without solder, but workability, mass productivity, and long-term reliability deteriorate
Solution Approach 1:
The invention replaces mechanical joining methods (swage joining, ultrasonic joining) with a thermal-chemical joining process using the low-melting glass phase joining material. This substitution enables solder-like workability and mass productivity while achieving superior long-term reliability through controlled metallurgical bonding, thus resolving both workability and reliability concerns
3Ease of manufacture
If conventional joining material is used for aluminum joining, then joining can be achieved, but connection resistance remains high compared to solder joining of copper
Solution Approach 1:
The invention creates a composite joining material structure consisting of a low-melting glass phase matrix embedded with electrical conductive particles. This composite structure combines the fluxing and bonding capabilities of the glass phase with the high electrical conductivity of the metal particles, achieving connection resistance levels comparable to copper solder joining while maintaining the ability to join hard-to-solder aluminum materials
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 achieves electrical joinability comparable to solder joining of easy-to-solder metals, with connection resistance reduced to levels comparable to solder joining, enhancing workability and long-term reliability.
Implementation Method 1
the oxide glass phase includes vanadium as a major constituent and at least one of phosphorus, barium and tungsten as an accessory constituent, and has a glass transition point of 390° C. or less
Implementation Method 2
The joining layer includes an oxide glass phase and a conductive metal phase
Implementation Method 3
a joined member joining treatment step of interposing the joining material between the joined members and carrying out resistance welding
Data Source
AI summary
It is an objective of the invention to provide a conductive joint article exhibiting electrical joinability comparable to that of solder joining of easy-to-solder joinable metals even when a joined member of the conductive joint article is made of a hard-to-solder joinable metal. There is provided a conductive joint article with conductive joined members electrically joined via a joining layer, at least one of the joined members being made of a hard-to-solder joinable metal. The joining layer comprises an oxide glass phase and a conductive metal phase. The oxide glass phase includes vanadium as a major constituent and at least one of phosphorus, barium and tungsten as an accessory constituent, and has a glass transition point of 390° C. or less. And, connection resistance between the joined members exhibits less than 1×10−5 Ω/mm2.