〉〉New Products

The Wiring Harness Composed of Aluminum Electric Wires
for an Automobile Seat
1.

INTRODUCTION

The automotive industry is now in the middle of a revolution period once in a hundred years, and the technological innovation is in a great progress especially in the fieldof so-called “CASE”, that is, Connected, Autonomous,Shared & Service and Electric.
The increase of the automotive equipment and its electronization are further accelerated by these technologicalinnovations and, as a result, this increase is also increasing the weight of vehicles. Solutions for the weight-reduction of vehicles are necessary under the circumstance
where the improvement of the fuel efficiency and thereduction of the CO 2 emission are highly required.
Accompanied with the increase of the automotive equipment and its electronization, the number of circuits in thewire harness (W/H), which supplied electric power andcontrol signals to each electric and electronic equipment
in a vehicle has been increasing, and the weight-reduction through replacing conventional copper electric wires
to aluminum electric wires has been in progress.
Recently, along with the increasing equipment in a vehicle, many circuits have been included in the W/H installedin the seat as well. On the other hand, an automobile seat
was used under a severe environment where various
solutions were supposed to stick such as seat cleaner
and a deodorizer, even though it was located in a cabin.
Therefore, such a risk as any connecting portion of thealuminum electric wire might be corroded made thereplacement of the aluminum electric wire more difficult
than in other W/H.
Accordingly, aiming at combining the weight-reduction
with a high reliability, we have applied our “α terminals”
shown in Figure 1, which had a high reliability protectedwith its hermetically sealed structure even under the environment where various solutions might stick and haverealized a seat W/H composed of aluminum electric
wires, which have never been installed in any automobile
seat before.

Figure 1

2.
2

COMPONENTS FOR THE W/H AND
PROBLEMS TO ADOPT ALUMIMUM
ELECTRIC WIRESW/H is a product constructed from various components
such as electric wires, terminals, connectors, exterior
components and others. As illustrated in Figure 2 forexample, the weight of copper electric wires used in aconventional W/H for an automobile seat generally
amounts to approximately 50% to 70% of the whole
weight of the W/H. In this development to use aluminumelectric wires instead of copper electric wires for an automobile seat W/H, we have accomplished a drastic
weight-reduction by replacing copper electric wires whichamount to a large portion of the weight composition ofthe W/H with aluminum electric wires.
ClampsTape

Terminals
Protectors

Connectors

Electric wires
68%

Figure 2

An example of a weight ratio of each component in aconventional seat W/H (composed of copper electricwires).

However, we had a problem of bimetallic corrosion (galvanic corrosion) when replacing copper electric wires
used in a W/H with aluminum electric wires. A terminal
crimped on the end of an electric wire in a W/H is generally made of either brass or copper alloy. The corrosion isproduced when the contact interface of the terminal andthe aluminum electric wire is exposed to water, oxygen,
and an electrolyte.
Therefore, when replacing copper electric wires withaluminum electric wires, protective measures against thecorrosion are necessary at the terminal connection portion of every circuit which may be exposed to water inorder to secure a stable electric connection between different metals of an aluminum electric wire and a terminal(brass or copper alloy).

Corrosion-proof terminals for aluminum wires,“α terminal” series.

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87

The Wiring Harness Composed of Aluminum Electric Wires for an Automobile Seat

Compressed insulation area

A crimped area is sealed
hermetically to prevent waterfrom sinking to avoid the corrosion
Cross section of compressed nsulation area

Terminal manufacturing process

Wire harness assembly process

Fiber laser welding

Inserting an electric wire

Figure 333.

Sectional structure of the crimped terminal of “α terminal series” and its manufacturing and assembly process.

FEATURES OF α TERMINAL SERIESA conventional treatment for the corrosion protection was
to seal the whole crimped portion with a resin to avoid
any contact between the aluminum conductor and theterminal against a solution. However, it has hardly spreadin general because of several problems such that anycavity of an existing connector housing was too small toaccept the terminal whose crimped portion was enlarged
with the sealing resin and that the production costbecame higher for the equipment and for the man-hour
required to apply the individual product treatment.
Then, we have developed the anti-corrosion terminal
for aluminum electric wires “α terminal series” as an innovative method for the corrosion protection. It has realized
an excellent anti-corrosion performance protected by anairtight tubular structure as shown in Figure 3 and also ahigh productivity and a low cost by completing the electrical connection and the anti-corrosion treatment at thesame time. “α terminal series” have been contributing in
expanding the aluminum electric wires in the automotive
W/H, as “α terminal series” were adopted to LANDCRUISER series from the 2015 year model, and havebeen producing actual results that not only more than 400
million pins were already implemented vehicles in themarket but also no failures were reported in the market 1).

4.
4

Crimping

er was quite severe against the aluminum electric wire.
Therefore, the replacement to the aluminum electric wire
was more difficult than in the other W/H. Further, when
adopting the aluminum wire in such an environment, avery high anti-corrosion performance is necessary at all
the connecting areas.
Accordingly, we proposed our solution to our customer
over and over to solve the reliability problem by applying
our “α terminal series” and asked our customer to give us
criteria of the anti-corrosion performance required for anautomobile seat. We have carried out the anti-corrosion
performance test of our “α terminal series” against as
many as 90 solutions which were supposed to stick, andhave confirmed that our “α terminal series” had a highanti-corrosion performance to secure the connection reliability without any increase of its electric resistance as aresult. Further, we have earned more trust from our customer as a result of these actual test data, and haveestablished our “α terminal series” as a de facto standard
for the anti-corrosion method of a seat W/H.

REPLACING COPPER ELECTRIC WIRESWITH ALUMINUM ELECTRIC WIRES IN
THE W/H OF AN AUTOMOBILE SEAT

Until today, we have been promoting the replacement tothe aluminum electric wire in the W/H installed in a bodyor a floor of vehicles supported by adopting our “α terminal series”. On the other hand, as mentioned above inChapter 1, the environment in the W/H for an automobileseat, where various solutions were supposed to stick
such as seat cleaner, disinfectant cleaner and a deodoriz-Figure 4

Wire harness for an automobile seat.

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The Wiring Harness Composed of Aluminum Electric Wires for an Automobile Seat

As a result, the seat W/H composed of aluminum electric wires to which our “α terminal series” were applied
was adopted to the seat made by Toyota Boshoku
assembled in a new model of Land Cruiser 300 launchedin August, 2022. And it was the first seat W/H composedof aluminum electric wires. 115 circuits out of 152 circuitsof the seat W/H for the automobile were replaced withaluminum electric wires (the aluminum electric wire rate:75%) and the weight of electric wires was reduced by
44% (approximately 200 g). As a matter of course, our“α terminal series” were applied to all the circuits
replaced with aluminum electric wires.
5.

5.

REFERENCE
1) Takanori Toyama, Kouhei Ikemoto et al.: “Development of theWiring System Technology to Realize its Weight-Reduction inVehicles”, Furukawa Electric Review No.53, 2022.

For more information, please contact:
Sales Planning & Marketing Department,
Sales Management Department,
Automotive Products Division
Contact form:
https://www.furukawa.co.jp/srm/form/index.php?id=jidosya

CONCLUSIONCONCLUSION

We have accomplished the weight-reduction of the seatW/H developed this time by replacing overall copper
electric wires with aluminum electric wires by as much as
44% of its weight of electric wires in comparison with theW/H composed with copper electric wires.
In the future, the weight of a seat W/H is expected toincrease further because more and more high-performance equipment will be mounted on an automobile
seat. And our continuous efforts will be required in solving the environmental problems for the future as well. We
are expanding the application of aluminum electric wires
further to an automotive W/H by applying our “α terminalseries” to promote the weight-reduction of automobiles
and the improvement of environmental performance, andwe will continue to contribute to realize the carbon-neutral society.

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