In the recent manufacturing industry, particularly in the automotive (EV) and electronics sectors, the “lightweighting” of components, “thermal management,” and “cost reduction” have become an urgent trilemma to solve. Historically, heavy and expensive “copper” has been widely used for parts requiring high electrical and thermal conductivity. However, due to soaring copper prices and concerns over supply risks, switching to alternative materials has become an urgent task.
Consequently, “Aluminum and Copper Composite” technology is currently attracting keen attention from procurement and design departments worldwide. This new technology, which fuses the excellent conductivity of copper with the lightness and low cost of aluminum, is overturning the conventional wisdom of “copper only.” In this article, from the perspective of Daiwa Aluminum Vietnam, we will explain the latest technological trends in aluminum-copper composites, their specific benefits, and the potential for supply chain optimization through production in Vietnam, incorporating quantitative data. By reading this article, you will gain specific insights into achieving significant cost reductions and lightweighting while maintaining quality.
Aluminum and Copper: Comparison of Physical Properties and Market Background
Soaring Copper Prices and Rising Need for Alternatives
Looking at market trends over the past 10 years, copper prices have shown extremely high volatility, becoming a factor hindering the stabilization of procurement costs. Based on London Metal Exchange (LME) data, copper prices generally trade at about 3.5 to 4 times the price of aluminum.
On the other hand, with the spread of electric vehicles (EVs), the demand for conductive and heat-dissipating parts such as busbars (distribution boards), battery terminals, and inverter heat sinks is predicted to increase at a Compound Annual Growth Rate (CAGR) of over 20%. Meeting this increased demand entirely with pure copper is becoming unrealistic in terms of both cost and weight.
Decisive Differences in Physical Properties
Comparing the characteristics of both materials clarifies the benefits of composites.
- Electrical Conductivity (IACS):
- Pure Copper (Tough Pitch Copper, etc.): 100% IACS (Standard value)
- Pure Aluminum (1000 series): Approx. 61-62% IACS
- Aluminum has about 60% of the conductivity of copper, but by increasing the cross-sectional area, it is possible to carry the same current.
- Specific Gravity (Density):
- Copper: 8.96 g/cm³
- Aluminum: 2.70 g/cm³
- Aluminum is only about 30% of the weight of copper. This is the key to lightweighting.
- Thermal Conductivity:
- Copper: Approx. 390 W/(m·K)
- Aluminum: Approx. 230 W/(m·K)
From this data, a simple calculation suggests that just “replacing copper with aluminum” could reduce part weight by approx. 50% or more. However, due to issues with contact resistance at connections and oxide films, simple replacement was difficult. This is where “composite material technology” has emerged.
Latest Technologies Realizing Aluminum-Copper Composites
Dissimilar metal joining requires advanced technology due to differences in melting points (Copper: 1085°C, Aluminum: 660°C) and the problem of brittle intermetallic compounds forming at the bonding interface. Here, we introduce the main technologies currently in practical use.
1. Clad Materials (Roll Bonding) and Busbar Applications
Clad materials are a technology where copper and aluminum are layered and bonded at the atomic level by rolling under high pressure. “CCA (Copper Clad Aluminum)” is a representative example.
- Features: A structure with copper on the surface and aluminum in the center is possible.
- Merits: Effective for communication cables utilizing the skin effect (the property where high-frequency current flows on the surface) and busbar terminal sections where contact resistance needs to be minimized.
- Cost Effect: By using aluminum for 85-90% of the volume ratio, material costs can be reduced by around 40% compared to pure copper.
2. Insert Casting (High-Pressure Die Casting, etc.)
Technological innovation is also progressing in the casting field, which is Daiwa Aluminum Vietnam’s specialty. This is a technology where copper pipes or terminals are placed inside a mold, and molten aluminum is poured around them.
- Cooling Performance: Adopted in heat sinks where refrigerant passes through copper pipes to dissipate heat via surrounding aluminum fins.
- Adhesion: Unlike cast iron, aluminum and copper react easily, so special plating treatments and temperature controls are used to realize strong interface bonding with low thermal resistance.
- Applications: In EV inverter cases and water-cooled heat sinks, by using copper only for heat source contact areas and making the entire housing aluminum, 30-40% lightweighting is achieved while maintaining cooling performance.
3. Friction Stir Welding (FSW)
A type of solid-state joining technology where a rotating tool is pressed against the joint, softening and mixing the metals using frictional heat.
- Merits: Since it does not involve melting, the formation of intermetallic compounds that increase electrical resistance can be minimized.
- Examples: Ideal for “partial compositing” where only the tip of an aluminum busbar (contact part with the mating terminal) is made of copper. This allows 90% of the entire part to be aluminum while maintaining connection reliability equivalent to copper.
Industry-Specific Applications and Benefits
Next-Generation Automotive (xEV) Sector
In EVs, high-voltage harnesses and busbars connecting batteries and motors tend to be thick and heavy to carry large currents. The weight of wire harnesses per vehicle can reach 20kg to 30kg.
By adopting aluminum-copper composites (copper terminals, aluminum body) here, lightweighting in the range of several kilograms becomes possible, directly linking to extended cruising range (improved energy efficiency). Also, technology development is progressing to reduce copper foil usage for negative electrode current collectors in lithium-ion batteries.
Power Electronics and 5G Base Stations
High heat generation density is a challenge for 5G base stations and data center servers.
“Hybrid heat sinks” combining the heat absorption of copper and the heat dissipation of aluminum have been reported to exhibit 20% higher cooling performance than pure aluminum while keeping costs to about 1/3 compared to pure copper.
Procurement Strategy via Vietnam Production: Daiwa Aluminum Vietnam’s Strengths
Dissimilar metal joining and advanced processing within Japan tend to have high processing costs (charges), creating a risk that material cost savings will be offset. Here, “production in Vietnam” holds significant meaning.
1. Suppression of Labor and Processing Costs
Labor costs in Vietnam’s manufacturing industry remain about 1/3 to 1/4 of those in Japan. Costs for parts requiring manual labor, such as inspection processes after dissimilar metal joining and finishing processes like deburring, can be significantly compressed.
2. Supply Chain Diversification (China Plus One)
Establishing procurement routes in Vietnam is important from a BCP (Business Continuity Plan) perspective to reduce dependence on China, a major copper refining country. Vietnam has concluded FTAs (Free Trade Agreements) with many countries, allowing for tariff benefits in the import and export of components.
3. Realizing Japanese Quality Locally
At Daiwa Aluminum Vietnam, we have transplanted Japanese technical standards directly to our Vietnam factory.
In particular, regarding insert casting technology in aluminum die casting and precision machining technology, we have established a strict quality management system (ISO 9001/14001, etc.) as a Japanese manufacturer. We have a system in place to provide “high-quality composite solutions at appropriate prices,” rather than “cheap and bad” products.
Summary
Aluminum and copper composite technology is not merely a means of cost reduction, but a strategic material for maximizing the performance of EVs and high-performance electronic devices.
- Lightweighting: Converting from copper to composites reduces part weight by up to 50%.
- Cost Down: Reduces material costs by 30-40% and reduces risk from copper market fluctuations.
- Leveraging Vietnam: By utilizing Daiwa Aluminum Vietnam’s production capacity, processing costs are suppressed and supply chain stability is realized.
As professionals in aluminum casting, Daiwa Aluminum Vietnam can offer composite proposals including copper insert casting. If you are a procurement or design manager facing challenges such as “wanting to lower the cost of copper parts” or “balancing heat measures and lightweighting,” please consult with us. We support optimal solutions from the design stage through to prototyping and mass production.