<s>
In	O
electronics	O
,	O
TO-3	B-Algorithm
is	O
a	O
designation	O
for	O
a	O
standardized	O
metal	O
semiconductor	B-Algorithm
package	I-Algorithm
used	O
for	O
power	O
semiconductors	O
,	O
including	O
transistors	B-Application
,	O
silicon	O
controlled	O
rectifiers	O
,	O
and	O
,	O
integrated	O
circuits	O
.	O
</s>
<s>
TO	O
stands	O
for	O
"	O
Transistor	B-Application
Outline	O
"	O
and	O
relates	O
to	O
a	O
series	O
of	O
technical	O
drawings	O
produced	O
by	O
JEDEC	O
.	O
</s>
<s>
The	O
TO-3	B-Algorithm
case	O
has	O
a	O
flat	O
surface	O
which	O
can	O
be	O
attached	O
to	O
a	O
heatsink	O
,	O
normally	O
via	O
a	O
thermally	O
conductive	O
but	O
electrically	O
insulating	O
washer	O
.	O
</s>
<s>
The	O
first	O
use	O
of	O
this	O
design	O
was	O
for	O
the	O
germanium	O
alloy-junction	O
power	O
transistor	B-Application
2N176	O
–	O
the	O
first	O
power	O
transistor	B-Application
to	O
be	O
put	O
into	O
quantity	O
production	O
.	O
</s>
<s>
Compared	O
with	O
equivalent	O
plastic	O
packages	O
,	O
the	O
TO-3	B-Algorithm
is	O
more	O
costly	O
.	O
</s>
<s>
The	O
TO-3	B-Algorithm
package	O
consists	O
of	O
a	O
diamond-shaped	O
base	O
plate	O
with	O
diagonals	O
of	O
and	O
.	O
</s>
<s>
The	O
metal	O
case	O
forms	O
the	O
third	O
connection	O
(	O
in	O
the	O
case	O
of	O
a	O
bipolar	O
junction	O
transistor	B-Application
this	O
is	O
typically	O
the	O
collector	O
)	O
.	O
</s>
<s>
TO-3	B-Algorithm
package	O
variants	O
for	O
integrated	O
circuits	O
can	O
have	O
more	O
than	O
two	O
leads	O
.	O
</s>
<s>
The	O
height	O
of	O
the	O
cap	O
and	O
the	O
thickness	O
of	O
the	O
leads	O
differs	O
between	O
variants	O
of	O
the	O
TO-3	B-Algorithm
package	O
.	O
</s>
<s>
The	O
two	O
pins	O
of	O
the	O
TO-41	O
package	O
end	O
in	O
soldering	O
pads	O
with	O
holes	O
in	O
them	O
to	O
make	O
it	O
easier	O
to	O
solder	O
wires	O
to	O
the	O
pins	O
for	O
point-to-point	O
construction	O
(	O
as	O
opposed	O
to	O
soldering	O
a	O
TO-3	B-Algorithm
package	O
on	O
a	O
printed	O
circuit	O
board	O
)	O
.	O
</s>
<s>
Otherwise	O
the	O
TO-41	O
package	O
has	O
the	O
same	O
dimensions	O
as	O
the	O
TO-3	B-Algorithm
package	O
.	O
</s>
<s>
The	O
different	O
outlines	O
are	O
now	O
defined	O
as	O
variants	O
of	O
TO-204	O
:	O
TO-3	B-Algorithm
is	O
renamed	O
to	O
TO-204-AA	O
,	O
TO-41	O
to	O
TO-204-AB	O
.	O
</s>
<s>
Common	O
transistors	B-Application
:	O
</s>
