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![[CASE4] TOKO, INC.](images/voice04_title.gif) |
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Soldering ultra fine wire of 20 micro-meter diameter
( m)
with SN100C |
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TOKO developed the world’s first IFT (Intermediate
Frequency Transformer) for transistor radios in 1956, and it has been the
company’s main business since then. Subsequently
their range of products has been widening, but TOKO remains the market leader
in the field of coil products. TOKO started the evaluation of lead-free
solders for coil products in April 1997.
In "snail" type coils the ends of the insulated copper wires
have to be joined to an external terminal. To burn off the insulating
enamel from the coil wire, it has to be dipped into solder at a high temperature,
typically 400 . At these temperatures "copper erosion" occurs
in the solder bath, resulting in thinning of the copper wire.
TOKO were searching for a solder which has minimal copper-erosion, good solderability,
which could be used in their existing. machines and which is less expensive
than the silver-containing lead-free solders.
In their search TOKO evaluated all the lead-free solder options. Finally, they
found the solder that meets all of their criteria, SN100C the alloy developed
by Nihon Superior
from the basic tin-copper eutectic ally by the addition of a very small
quantity of Ni. Some of their lines started commercial production with
this alloy in April 2000.
The trend in electrical devices is towards a reduction in size and in coils
this means a reduction in the thickness of copper wire down to as low as 20 m
diameter.
"If such ultra-fine wires as these," said the manufacturing manager of section #2 of the coil application division, "are dipped into high
temperature solder, they could vanish in the pot completely, rather than just
being thinned. We have been using this new solder (SN100C)
in mass production for more than two years and we can find no problems with
solderability, no problems in using our machines with this alloy and no problems
in maintaining the quality of the solder-joints."
TOKO has now set a schedule for introducing SN100C on all lines. When
asked about their reason for this change the response of this customer
is that they are keen to adopt SN100C as their contribution towards the preservation
of the environment. |
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Interviewed by The Nikkan Kogyo Shimbun, Ltd. |
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