Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1999-08-18
2002-07-30
Cuneo, Kamand (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S261000, C361S768000
Reexamination Certificate
active
06426467
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to film carrier tapes, especially, to film carrier tapes used in a tape carrier bonding (Tape Automated Bonding) process and methods of evaluating the film carrier tapes.
BACKGROUND OF THE INVENTION
Conventional film carrier tapes have a plurality of lead terminals with an end thereof being connected to a semiconductor chip and the other end being provided with an electrical sorting (screening) pad.
FIG. 13
is a schematic plan view showing a conventional film carrier tape. An insulating film
100
has sprocket holes
102
formed along both sides thereof for transport and positioning purposes. Also, the insulating film
100
has in the middle thereof semiconductor chip mounting holes
104
where semiconductor chips are mounted. Further, the insulating film
100
is provided thereon with a plurality of lead terminals
106
each extending over the semiconductor chip mounting hole
104
at one end thereof, while an electrical sorting pad
108
is formed at the other end of each of the lead terminals
106
.
Demands on the semiconductor chip for higher integrity and high performance in recent years have resulted in the semiconductor chip having more input and output terminals (bonding pads on the semiconductor chip) and hence more lead terminals
106
. Therefore, the pitches are decreasing between the lead terminals
106
. As a result, the pitches between the lead terminal
106
of a film carrier tape are in some cases smaller than the smallest pitch required to provide the electrical sorting pad
108
.
Therefore the electrical sorting pads
108
of such a film carrier tape are configured as shown in
FIG. 14
for example: the electrical sorting pads
108
are disposed along a zigzag line.
However, the region of the insulating film (not shown) where the electrical sorting pads
108
are formed is unnecessary and cut off along line III—III shown in
FIG. 14
when the semiconductor chip is mounted on the insulating film. The zigzag configuration of the electrical sorting pads
108
shown in
FIG. 14
increases the area of the region of the insulating film where the electrical sorting pads
108
are formed. In other words, a larger portion of the insulating film is wasted. This results in less packages (semiconductor chips) being mounted on the film carrier tape, and hence higher production costs. Besides, the tester cannot be equipped with an enough number of lead probes (measurement terminals) to match the increased number of the electrical sorting pads
108
.
To solve these problems,
FIG. 15
suggests a film carrier tape of which adjacent lead terminals
106
share a single electrical sorting pad
108
.
The film carrier tape having such electrical sorting pads
108
can accommodate more lead terminals
106
without additional electrical sorting pads
108
; thereby a smaller portion of the insulating film
100
, which will be cut off along line IV—IV shown in
FIG. 16
, is wasted. Apart from that, the film carrier tape uses a smaller number of electrical sorting pads
108
and can be configured so that the number of the electrical sorting pad
108
matches the number of lead probes of a conventional tester.
However, with the film carrier tape shown in
FIG. 16
, a short circuit cannot be detected which possibly occurs between adjacent lead terminals
106
that commonly share an electrical sorting pad
108
.
To solve those problems, Japanese Laid-Open Patent Application No. 6-104316/1994 (Tokukaihei 6-104316, published on Apr. 15, 1994) discloses a film carrier tape shown in FIG.
17
. The film carrier tape has lead terminal groups each consisting of one or more lead terminals
106
, and a common electrical sorting pad
108
is formed for each lead terminal group. This configuration enables detection of short circuits between adjacent lead terminals
106
.
However, the film carrier tape shown in
FIG. 17
disenables the detection of broken conductivity of the lead terminal
106
belonging to a lead terminal group when a delivery inspection (an inspection before delivery of the film carrier tape from the production line) is conducted in the manufacturing process of the film carrier tape on which no semiconductor chip is yet mounted.
FIG. 18
shows an example of delivery inspection conducted in the manufacturing process of the film carrier tape to detect a broken lead terminal
106
. In the delivery inspection, the lead terminals
106
, extending over the semiconductor chip mounting hole
104
, are caused to commonly contact an electrode plate
110
, whereas the electrical sorting pads
108
are caused to contact the lead probes
112
of a tester. A broken lead terminal
106
is detected by the securing card
114
of the tester confirming electrical conductivity between the lead probes
112
to the electrode plate
110
.
The tester therefore comes short of detecting the broken lead terminal
106
belonging to the lead terminal group shown encircled by broken lines in
FIG. 19
for example, since the electrical sorting pad
108
of that lead terminal group is electrically connected to the electrode plate
110
as long as the other lead terminal
106
of the same lead terminal group is in good conditions. The film carrier tape thus passes the delivery inspection, and the defect is not found until an electrical sorting process after semiconductor chips are mounted, which inevitably leads to greater production cost.
SUMMARY OF THE INVENTION
The present invention has an object to offer film carrier tapes, and methods of evaluating thereof, capable of curbing increase in production cost that would otherwise results from increased use of film materials and reducing the number of measurement terminals required by a tester used for an inspection after the mounting of semiconductor chips as well as detecting all broken lead terminals in a delivery inspection conducted in the manufacturing process of the film carrier tapes.
In order to accomplish the above object, the film carrier tape in-accordance with the present invention includes:
a plurality of lead terminals that are each disposed on an insulating film and provided with an end connected to a semiconductor chip and another end having an electrical sorting pad,
wherein the electrical sorting pads of two or more of the plurality of lead terminals that are not adjacent to one another are electrically separated from one another and configured so that electrical sorting can be simultaneously conducted thereon through the two or more of the plurality of lead terminals.
With the above arrangement, in a delivery inspection to detect broken conductivity of a lead terminal which is conducted in the manufacturing process of a film carrier tape before a semiconductor chip is mounted, an electrode plate or the like is caused to commonly contact the ends of the lead terminals which will be connected to the semiconductor chip. Subsequently, electric connection (conductivity) is confirmed between the electrode plate and the electrical sorting pads provided at the other ends of the lead terminals to detect broken conductivity of each lead terminal individually.
If the film carrier tape is such that two or more lead terminals share a single electrical sorting pad, those lead terminals are connected electrically parallel to one another between the electrical sorting pad and the electrode plate. The parallel configuration of the lead terminals allows conductivity to be detected between the electrical sorting pad and the electrode plate even if one or some of the parallel lead terminals is/are broken. In other words, broken conductivity is not detected unless all the lead terminals are broken. In such a case, the film carrier tape passes the delivery inspection, and the defect is not found until an electrical sorting process after a semiconductor chip is mounted, which inevitably leads to greater production cost.
To tackle the problems, according to the present invention, the electrical sorting pads of two or more of the lead terminals that are not adjacent to one another are configured so as to allow a bro
Gyouten Seijirou
Murahashi Shun-ichi
Cuneo Kamand
Sharp Kabushiki Kaisha
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