Play Meter

By William Arkush
Microelectronics Division Manager
Exidy, Incorporated
Sunnyvale, California
THE INTEGRATED CIRCUIT:
The 'nuts and bolts'
The integrated circuit is an assembly
of component parts . Because of this ,
packaging considerations are equally
as important as the device function .
Functionally , the component parts
are: the silicon chip , the mounting
substrate , the die attach material , the
package , the lead frame, the wire
bonds, the package lid , and hermetic
seal.
With so many items comprising
the integrated circuit , the possibilities
of things going wrong with it are
greater than if the part was a unitized
construction . There are the bumped
lead devices which directly adhere to
the substrate through the use of
th ermo-compression bonding . This
system like the TAB ( tape auto-
mated bonding) is good for auto-
mated assembly-but very few semi-
conductor manufacturers are build-
ing the die for this structure, the
assembly
procedures
are
not
completely defined, the assembly
equipment is hard to obtain and
expensive, and not many device
types are available through these
processes. Therefore, the semicon-
d uctor industry remains a wire bond
and substrate format.
This is where the circuit die is
pasted down to the substrate of the
carrier or package with conductive
epoxy ( palladium-silver) , a noble
solder paste ( silver-iridium), a eutec-
tic die attach ( gold) , or a thermo-
compression ball bonding in the case
of the flip chip arrangement.
After the die is pasted down using
one of these technologies, the wire
bonding is the next assembly step .
For those devices which have sixteen
leads , the die has sixteen metalized
lands or pads . These are the
terminations for the wire bonds
between the lands and the le_ad
attach terminations. A 1-mill wire
( .001 inch) is then used to inter-
connect the chip die to the legs of the
package .
The standard wire used is alumin-
um or gold . Both materials can be
attached in one of these methods:
ultrasonic.
thermocompression ,
wedge, or ball bonding . Aluminum
wire interconnections are applied
through the ultrasonic and wedge
bonding equipment which does not
require the working area to be
heated .
New ROMs to modify Sprint 4
As a result of many field requests by
Sprint 4 owners, Atari has developed
new Sprint 4 ROMs to modify the
existing game p,lav .
The new ROMs increase player
challenge and competition, while
maintaining the excitement of the
Sprint 4 driving experience, reports
an Atari spokesman .
The new ROMs are designed to
decrease the size of the cars , limit the
number of drones according to one -,
two-, and three -player games, and
allow a player bonus for the high
score in a four -player game ( option
selectable) . Any start switch starts all
players with credit and subsequent
coins now start players immediately
into the game .
Operators can obtain this new
Sprint 4 modification ROM for under
$150 through an Atari distributor,
the company reports .
In compression , gold wire is
usually gold ball or thermocompres-
sion bonded. The working area and
the wire are heated to the point
where they soften and then a
pressure is applied while the wire and
metalization area are cooled . This
method is slower than stitch bonding
with ultrasonics, because the time
required to heat the junction is
greater than ultrasonics where the
connection is made in a fraction of a
second . In fact , a semi-automatic
ultrasonic wire or wedge bonder and
a skilled operator can produce an
interconnection every second . That
is, every wire bond requires two
operations so there are two seconds
consumed for each completed inter-
connection .
This means, at best , a sixteen-pin
package can be produced every 48
seconds. Sixteen pins at 2 seconds
each plus one -second relocate time
for each pin , ( 16 pins X 2 seconds)
+ ( 16 pins X 1 second) = 48
seconds/ device.
Therefore , at best, a superb
machine operator turns out about 60
to 80 parts per hour at about 1 +one
part per minute. Multiply this by 7 +
productive hours and one operator
produces 400 to 600 parts per day
per operator .
WEAK LINK IN PRODUCTION
This system of semi-automatic
wire bonding is the weak link in
production . This is why the semicon-
ductor manufacturers are seriously
considering the TAB system of fully
automatic chip bonding. With auto-
mated equipment we are looking at
1200 parts per hour as a con-
servative average .
What a difference the production
rate will be when more flip chip