Japan has developed a new conductive material with 100 times the current carrying capacity of copper wire

The Japan Industrial Science and Technology Research Institute (hereinafter referred to as "Sanken") has developed a new material that combines a single layer of carbon nanotubes (CNTs) and copper (Cu) to achieve the same conductivity as copper and a current carrying capacity of about 100 times that of copper (also known as maximum current density).

According to the institute, this CNT-Cu composite material can not only pass high currents, but also is lightweight and resistant to high temperatures, so it can be used
as a wiring material for ultra-small high-performance semiconductor chips.

Until now, the overall wiring of semiconductor chips and the wiring materials between chips generally use copper, aluminum (Al), gold (Au) and other metals
.
However, although the conductivity of these metals is high, the current carrying capacity is not necessarily large
.
When a high voltage of a certain value or higher is applied, this voltage causes the atomic structure to collapse, causing a sharp increase in resistance and eventually a wire breakage
.

In terms of conductivity and ampacity, the new material combines the high ampacity of CNT and the high conductivity of Cu (a).

Previously, no material with high ampacity and high conductivity was found, but CNT-Cu composites achieve both properties (b).

From the perspective of application, with the advancement of miniaturization technology, the current carrying capacity required for wiring semiconductor chips and other devices has gradually increased
.
According to the comprehensive research institute, by 2015, the required ampacity will reach 1 million (106) A/cm2
that Cu and Au cannot achieve.
"Nanocarbon materials" such as CNT and graphene have a current
carrying capacity of about 1 billion (109) A/cm2.
This is because carbon atoms have a strong coupling ability, and even if a high voltage is applied, it is difficult to cause the atomic structure to collapse
.
However, the conductivity of this material is less than 1/100
of that of Cu and Au.
Previously, researchers had not found materials
with comparable ampacity to CNTs and electrical conductivity equivalent to Cu.

CNT inhibits the diffusion of Cu

CNT-Cu composite material is composed of CNT and Cu, which for the first time achieves both of the above characteristics
.
Its ampacity is 6.
3×108A/cm2, which is about 100 times
that of Cu.

According to the comprehensive research institute, the reason why the new material can obtain such a high ampacity is because the CNT can inhibit the diffusion
of Cu.
In this CNT-Cu composite, CNT and Cu form a structure like "reinforced concrete", and CNT plays a role
in enhancing the "strength" of Cu at high voltage.

At room temperature, the conductivity of this composite material is comparable
to Cu.
However, even at a high temperature of about 200 °C, the conductivity of the new material will not be significantly reduced, which is even better
than Cu.

The conductivity of CNT-Cu composites and Cu changes
at different temperatures.
Compared with Cu, CNT-Cu composites have less
change in conductivity due to temperature.

According to the comprehensive research institute, the production process of the new material is basically electroplating the CNT in a solution containing Cu ions
.
The key point is to slowly electroplate the CNT with a current density of 1m~5mA/cm2 in organic solution, rather than quickly plated copper in
aqueous solution.
This allows the inside of the CNT construct to be filled with Cu.

Overview
of the manufacturing process of CNT-Cu composites.
The vertical alignment single-layer CNT developed by the production comprehensive research institute and Japan Zeon and others was changed to horizontal orientation, and copper plating was successively carried out in organic and aqueous solutions
.

There is currently a price gap of more than 1,000 times

The biggest problem with this composite material is that the cost of single-layer CNTs is still high
.
Currently, the cost of a single-layer CNT is 1,000 yen~10,000 yen/g (depending on the purity), which is similar to Au, which is about 4,300 yen/g
.
The cost of Cu is only about 0.
76 yen/g, and there is a huge price gap
between single-layer CNTs.

In manufacturing single-layer CNTs this time, the company adopted the "Super Growth Method," a process
that can manufacture high-purity single-layer CNTs, jointly developed by the institute and companies such as Japan's Zeon.
Zeon plans to start full-scale mass production of single-layer CNTs
using the over-growth method in 2015.
In the future, it is possible to reduce the manufacturing cost to about
10 yen/g.

According to the company, it will work with manufacturers to develop specific applications for new materials and promote practical
use.