<s>
A	O
semiconductor	B-Algorithm
package	I-Algorithm
is	O
a	O
metal	O
,	O
plastic	O
,	O
glass	O
,	O
or	O
ceramic	O
casing	O
containing	O
one	O
or	O
more	O
discrete	O
semiconductor	O
devices	O
or	O
integrated	O
circuits	O
.	O
</s>
<s>
Individual	O
components	O
are	O
fabricated	B-Architecture
on	O
semiconductor	B-Architecture
wafers	I-Architecture
(	O
commonly	O
silicon	O
)	O
before	O
being	O
diced	O
into	O
die	O
,	O
tested	O
,	O
and	O
packaged	O
.	O
</s>
<s>
A	O
semiconductor	B-Algorithm
package	I-Algorithm
may	O
have	O
as	O
few	O
as	O
two	O
leads	O
or	O
contacts	O
for	O
devices	O
such	O
as	O
diodes	O
,	O
or	O
in	O
the	O
case	O
of	O
advanced	O
microprocessors	B-Architecture
,	O
a	O
package	O
may	O
have	O
hundreds	O
of	O
connections	O
.	O
</s>
<s>
In	O
addition	O
to	O
providing	O
connections	O
to	O
the	O
semiconductor	O
and	O
handling	O
waste	O
heat	O
,	O
the	O
semiconductor	B-Algorithm
package	I-Algorithm
must	O
protect	O
the	O
"	O
chip	O
"	O
from	O
the	O
environment	O
,	O
particularly	O
the	O
ingress	O
of	O
moisture	O
.	O
</s>
<s>
To	O
make	O
connections	O
between	O
an	O
integrated	O
circuit	O
and	O
the	O
leads	O
of	O
the	O
package	O
,	O
wire	B-Algorithm
bonds	I-Algorithm
are	O
used	O
,	O
with	O
fine	O
wires	O
connected	O
from	O
the	O
package	O
leads	O
and	O
bonded	O
to	O
conductive	O
pads	O
on	O
the	O
semiconductor	O
die	O
.	O
</s>
<s>
Aerospace	O
devices	O
in	O
flat	B-Algorithm
packs	I-Algorithm
may	O
use	O
flat	O
metal	O
leads	O
secured	O
to	O
a	O
circuit	O
board	O
by	O
spot	O
welding	O
,	O
though	O
this	O
type	O
of	O
construction	O
is	O
now	O
uncommon	O
.	O
</s>
<s>
Sockets	O
are	O
still	O
used	O
for	O
experimental	O
,	O
prototype	O
,	O
or	O
educational	O
applications	O
,	O
for	O
testing	O
of	O
devices	O
,	O
for	O
high-value	O
chips	O
such	O
as	O
microprocessors	B-Architecture
where	O
replacement	O
is	O
still	O
more	O
economical	O
than	O
discarding	O
the	O
product	O
,	O
and	O
for	O
applications	O
where	O
the	O
chip	O
contains	O
firmware	B-Application
or	O
unique	O
data	O
that	O
might	O
be	O
replaced	O
or	O
refreshed	O
during	O
the	O
life	O
of	O
the	O
product	O
.	O
</s>
<s>
Devices	O
with	O
hundreds	O
of	O
leads	O
may	O
be	O
inserted	O
in	O
zero	B-General_Concept
insertion	I-General_Concept
force	I-General_Concept
sockets	O
,	O
which	O
are	O
also	O
used	O
on	O
test	O
equipment	O
or	O
device	O
programmers	O
.	O
</s>
<s>
A	O
very	O
few	O
early	O
semiconductors	O
were	O
packed	O
in	O
miniature	O
evacuated	O
glass	O
envelopes	O
,	O
like	O
flashlight	O
bulbs	O
;	O
such	O
expensive	O
packaging	B-Algorithm
was	O
made	O
obsolete	O
when	O
surface	B-Application
passivation	I-Application
and	O
improved	O
manufacturing	O
techniques	O
were	O
available	O
.	O
</s>
<s>
Proper	O
fabrication	B-Architecture
practices	O
using	O
properly	O
qualified	O
PEMs	O
can	O
be	O
used	O
for	O
spaceflight	O
.	O
</s>
<s>
Multiple	O
semiconductor	O
dies	O
and	O
discrete	O
components	O
can	O
be	O
assembled	O
on	O
a	O
ceramic	O
substrate	B-Architecture
and	O
interconnected	O
with	O
wire	B-Algorithm
bonds	I-Algorithm
.	O
</s>
<s>
The	O
substrate	B-Architecture
bears	O
leads	O
for	O
connection	O
to	O
an	O
external	O
circuit	O
,	O
and	O
the	O
whole	O
is	O
covered	O
with	O
a	O
welded	O
or	O
frit	O
cover	O
.	O
</s>
<s>
A	O
modern	O
example	O
of	O
multi-chip	O
integrated	O
circuit	O
packages	O
would	O
be	O
certain	O
models	O
of	O
microprocessor	B-Architecture
,	O
which	O
may	O
include	O
separate	O
dies	O
for	O
such	O
things	O
as	O
cache	B-General_Concept
memory	I-General_Concept
within	O
the	O
same	O
package	O
.	O
</s>
<s>
In	O
a	O
technique	O
called	O
flip	B-Device
chip	I-Device
,	O
digital	O
integrated	O
circuit	O
dies	O
are	O
inverted	O
and	O
soldered	O
to	O
a	O
module	O
carrier	O
,	O
for	O
assembly	O
into	O
large	O
systems	O
.	O
</s>
<s>
The	O
technique	O
was	O
applied	O
by	O
IBM	O
in	O
their	O
System/360	B-Application
computers	O
.	O
</s>
<s>
Semiconductor	B-Algorithm
packages	I-Algorithm
may	O
include	O
special	O
features	O
.	O
</s>
<s>
An	O
ultraviolet	B-General_Concept
erasable	I-General_Concept
programmable	I-General_Concept
read-only	I-General_Concept
memory	I-General_Concept
device	O
needs	O
a	O
quartz	B-General_Concept
window	O
to	O
allow	O
ultraviolet	O
light	O
to	O
enter	O
and	O
erase	O
the	O
memory	O
.	O
</s>
<s>
Just	O
like	O
vacuum	O
tubes	O
,	O
semiconductor	B-Algorithm
packages	I-Algorithm
standards	O
may	O
be	O
defined	O
by	O
national	O
or	O
international	O
industry	O
associations	O
such	O
as	O
JEDEC	O
,	O
Pro	O
Electron	O
,	O
or	O
EIAJ	O
,	O
or	O
may	O
be	O
proprietary	O
to	O
a	O
single	O
manufacturer	O
.	O
</s>
