Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With provision for cooling the housing or its contents
Reexamination Certificate
2001-06-29
2003-01-21
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With provision for cooling the housing or its contents
C257S779000, C257S700000, C257S695000, C257S691000, C257S738000, C257S758000, C257S737000, C257S668000
Reexamination Certificate
active
06509643
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a TAB (Tape Automated Bonding) tape with a stiffener, which is a combined cooling plate and stiffener being a so-called “stiffener”, and a tape BGA (Ball Grid Array) semiconductor device using the same.
BACKGROUND OF THE INVENTION
A one-metal TAB tape is usual as a TAB tape, and such one-metal TAB tape is prepared by forming a wired pattern on either surface of an insulating film made of polyimide resin used for a tape base material.
In this respect, there is a tendency to direct high frequency in chips mounted on a personal computer and the like, whereby a need for a circuit having a high transmission rate increases. With increase in data transmission rate, a new problem of noise generation due to electromagnetic field coupling between leads appears on a fine-pitch wiring in a TAB tape, and it became impossible to ignore such problem. For instance, there is such a problem that a ringing (resonance) phenomenon arises between leads disposed with a spacing of 30 &mgr;m, so that a signal wave form of clock pulse deforms remarkably.
In order to overcome such problem as described above, the following constitution is considered effective. Namely, the constitution is arranged in such that a ground layer is disposed on the surface opposite to a side of a tape base material on which a wired pattern has been formed, whereby influence of noise due to mutual inductance between wirings due to use of leads in a package does not result in a problem in view of operating characteristics.
In these circumstances, a two-metal (double layered) TAB tape wherein a wired pattern has been formed on opposite surfaces of a polyimide resin insulating film used for a tape base material, respectively, is noticed as a TAB tape capable of eliminating such problem as described above.
A semiconductor device having a conventional T-BGA (Tape BGA) structure wherein the two-metal TAB tape is used is shown in FIG.
5
.
First, a circuit pattern
21
with a signal circuit containing solder ball pad sections
26
, a bonding pad section
27
, and a routed lead section is formed on either surface of a tape base material
1
composed of a polyimide resin insulating film. Then, a part of the circuit pattern
21
is insulated with an insulating film
2
made from a photo solder resist (PSR). A ground layer
6
is disposed on the other surface of the tape base material
1
. The above-described solder ball pad sections
26
and the bonding pad section
27
are electrically connected to the ground layer
6
through a conductive via section
3
, whereby a two-metal TAB tape
50
is constituted. The resulting two-metal TAB tape
50
is bonded to a stiffener
40
wherein a concave portion
41
for mounting a semiconductor chip has been defined on a central portion of a metal sheet through an adhesive
5
to obtain a TAB tape with a stiffener.
Then, a semiconductor chip
7
is bonded to the concave portion
41
of the above-described stiffener
40
with the use of a device-fixing agent
9
as its adhesive. An electrode
71
of the semiconductor chip
7
is connected with the above-described circuit pattern
21
by a bonding wire
8
, and further the above-described semiconductor chip
7
and the bonding wire
8
are sealed by means of a sealing resin
100
, whereby the semiconductor device is constituted. Solder balls
4
are installed on the respective solder ball pad sections
26
.
According to the above-described constitution, there is the ground layer
6
being an electrically conductive layer beneath the tape base material
1
being a thin insulating layer. Accordingly, eddy currents flow in the ground layer
6
along directions wherein magnetic fluxes produced by electric currents flowing through respective wirings are cancelled in the case when a high frequency signal is loaded on the wirings in the signal circuit. As a result, an apparent inductance and an apparent inductive crosstalk can be reduced, whereby reliability and speeding up in a velocity of propagation of electrical signals are achieved.
However, two-metal and one-base material TAB tape is very expensive, so that a T-BGA semiconductor device prepared by using such TAB tape becomes very expensive, consequently.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an inexpensive TAB tape with a stiffener wherein a two-metal and two-base material TAB tape having a structure prepared by bonding an ordinary single metal TAB to a tape material of a ground layer is used for solving the above-described problems and improving electrical characteristics thereof, and as a result, equivalent reliability and equivalent speeding up in a velocity of propagation of electrical signals to those of the case where a conventional two-metal and one-base material TAB tape is employed are achieved as well as to provide a T-BGA semiconductor using such TAB tape with a stiffener as described above.
In order to achieve the above-described object, the present inventions have been constituted as described hereinafter.
(1) A TAB tape with a stiffener according to a first invention as claimed in claim
1
is characterized by that a circuit pattern containing a signal circuit is formed on either surface of a first tape base material made from an insulating film; a part of the circuit pattern is covered with an insulating film; a via hole penetrating the first tape base material is defined on a connecting regional section used for a via, which is one of connection regions required for electrical connections and is not covered with the insulating film to constitute a one-metal TAB tape; the one-metal TAB tape is bonded to a tape for second metal prepared by providing a metallic film layer on either surface of a second tape base material made from an insulating film through an adhesive layer on which an opening corresponding to the via hole has been defined in such that the metallic foil layer of the tape for second metal is positioned on the opposite surface of the first tape base material; an exposed portion for wire bonding, which has not been covered with the one-metal TAB tape, is allowed to remain on the metallic foil layer in case of the bonding operation; and a stiffener made from a metallic sheet being bonded onto a side of the tape for second metal of a two-metal and two-base material TAB tape prepared by the above-described bonding operation through an adhesive.
According to such TAB tape with a stiffener as described above, a two-metal and two-base material TAB tape having a structure wherein a one-metal TAB tape, which is easily manufactured, is bonded to a tape used for a second metal prepared by providing a metallic foil layer on either surface of a second tape base material made from an insulating film through an adhesive layer, on which an opening corresponding to the above-described via hole has been defined, in such that the metallic foil layer of the above-described tape for second metal is positioned on the other surface of the above-described first tape base material has been used. Thus, it can be very inexpensively manufactured as compared with the case where a conventional two-metal TAB tape is employed.
Furthermore, this TAB tape with a stiffener has such structure wherein a connecting regional section used for a via being a part of a circuit pattern is disposed on either surface of a first tape base material, while a part of a metallic foil layer made of, for example, copper foil is disposed on the other surface thereof, and a blind via hole that extends from the connecting regional section for via to reach the metallic foil layer through a via hole in the first tape base material and an opening in an adhesive layer is defined. Hence, when the connecting regional section for via on the upper edge of the hole is electrically connected with a part of the metallic foil layer on the bottom of the hole in the blind via hole, a potential of the metallic foil layer can drop to a ground potential.
As a manner for attaining an electrical connection in the blind via, there are, for exampl
Ohtaka Tatsuya
Suzuki Sachio
Erdem Fazli
Flynn Nathan J.
Foley & Lardner
Hitachi Cable Ltd.
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