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Case No.7
Electrocuted while repairing semi-conductor
manufacturing equipment |
Click Here |
[Circumstances of Incident]
This accident occurred in a semi-conductor
manufacturing plant where 4Mbit memories
and other products are produced.
The victim in this accident worked
for a
subcontractor of the parent company,
which
owned the plant where the victim and
his
colleagues were engaged in silicon
wafer
polyimide processing and back face
processing.
On the day of the accident, two maintenance
workers, including one leader, started
repair
work when a sputtering unit used in
the processing
wafer surface failed.
As the first step, workers tried to
replace
a power amplifier and an intermediate
amplifier
with no success in restoring the functions
of the unit. They then checked the
voltage
inside the high-frequency power source
unit
and detected abnormal figures in the
voltages
of four inspection terminals.
After taking a rest break, the leader
made
a telephone call at about 2:30 to the
maintenance
company responsible for the unit to
report
their failure in repairing the sputtering
unit. He came back to the repair site
about
one hour later, and found the victim
lying
unconscious on the floor between the
sputtering
unit and the power source rack.
The victim's body showed evidence of
electric
current passing through from the first
and
second fingers of the right hand to
both
knees and legs. In addition, some rubber-like
material was adhering to a burned spot
near
the bottom of the metal cap on the
top of
the power amplifier in the high-frequency
power unit.
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[Causes]
The following can be cited as the causes
of this accident.
1. The power source was turned on.
Although the leader had turned off
the power
switch of the high-frequency power
unit by
himself before taking break, the victim
turned
on the switch while the leader was
talking
to the maintenance company by phone
to locate
the failure and perform other repair
work.
2. Personal protective equipment to
prevent
electric shock was not used.
The victim was wearing polyester work
clothes
for the clean room, with a hood and
anti-static
rubber shoes, but no anti-shock protective
equipment.
3. Wrong operational procedures
The sputtering unit handling manual
indicates
that the unit can generate electrical
discharges
and requires adequate precautions for
high
voltages. However, the worker started
the
operation without reconfirming the
contents
of the manual.
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[Type of business] Electronic and electric equipment parts
manufacturing industry
[Type of accident] Electric shock
[Number of victims]One fatality |
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