Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With dam or vent for encapsulant
Reexamination Certificate
1998-09-28
2003-12-30
Graybill, David E. (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With dam or vent for encapsulant
Reexamination Certificate
active
06670696
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a TCP semiconductor device using solder resist having appropriate flexibility and a liquid crystal panel display using such a device, and also concerns a testing method for disconnection of the wiring pattern thereof.
BACKGROUND OF THE INVENTION
The TCP (Tape Carrier Package) semiconductor device having a flexible bending property is referred to as a flex TCP semiconductor device. The flex TCP semiconductor device is used as a package for driver semiconductors especially in a liquid crystal panel which has a small frame portion.
Recently, there has been a strong trend toward large-size liquid crystal panels, and at present, those panels exceeding 13 inches have been produced for use in notebook PCs (Personal Computers). Therefore, there are ever-increasing demands for the development of flex TCP semiconductor devices used for large-size liquid crystal panels.
FIG.
7
(
a
) is a plan view that shows a schematic construction of a bicolor flex TCP semiconductor device
101
in which two types of solder resists are formed, and FIG.
7
(
b
) is a cross-sectional view taken along line A-A′ in FIG.
7
(
a
).
In the construction of the bicolor flex TCP semiconductor device
101
, a driver IC chip
104
is electrically connected to a tape carrier
103
that has been formed by using a film-shaped polyimide substrate
102
.
The tape carrier
103
has a copper wiring pattern that is constituted by a pair of slits
105
, inner leads
106
, input-side outer leads
107
, output-side outer leads
108
and a test pad
109
, pieces of epoxy solder resist
110
, pieces of polyimide solder resist
111
and pieces of polyimide solder resist
112
that insulate and coat the slits
105
and the copper wiring pattern, and sprocket holes
113
that are used for leading and positioning the polyimide substrate
102
.
In particular, on the copper wiring pattern are provided two types of solder resists, that is, the hard epoxy solder resist
110
with a young's modulus of 380±80 kgf/mm
2
and the polyimide solder resist
111
having flexibility with a young's modulus of 50±20 kgf/mm
2
.
By utilizing its great young's modulus, the epoxy solder resist
110
plays two roles for preventing the occurrence of bleed (flowing of solder resist mainly constituted by its solvent ingredients, after the printing process) in the polyimide solder resist
111
, and for preventing the peeling of the edge of the polyimide solder resist
111
in a tin-plating formation process upon manufacturing the tape carrier
103
, which will be described later. With this arrangement, the patterning precision of the polyimide solder resist
111
can be improved.
Moreover, the pieces of polyimide solder resist
112
with a young's modulus of 50±20 kgf/mm
2
are formed on the undersurface (the back side of the surface on which the copper wiring pattern is formed) of the slits
105
.
The driver IC chip
104
is electrically connected to the inner leads
106
through Au bumps
114
, and the junctions and their adjacent portions are sealed with resin
115
.
Next, referring to
FIG. 8
, an explanation will be given of manufacturing processes of the tape carrier
103
in the bicolor flex TCP semiconductor device
101
having the above-mentioned construction.
First, the surface of the polyimide substrate
102
(Upilex: Trademark of Ube Industries, Ltd.) is coated with a bonding agent (process 1), and a device hole, a pair of slits
105
and sprocket holes
113
, etc. are formed by punching out the polyimide substrate
103
with a die (process 2).
Next, the polyimide substrate
102
is laminated with copper foil having a thickness of either 18 &mgr;m, 25 &mgr;m or 35 &mgr;m (process 3). Moreover, pieces of polyimide solder resists
112
are formed over the pair of slits
105
from the side opposite to the surface on which the copper wiring pattern is to be formed later (process 4).
Then the copper-foil surface is coated with photoresist serving as an etching mask (process 5). Further, the photoresist is printed as a desired pattern through exposure (process 6), and developed (process 7). Here, photoresist serving as an etching mask is also formed over the device hole (process 8). Thereafter, the desired copper wiring pattern is formed by dipping the entire copper foil into a copper-foil etching liquid (process 9). After the copper wiring pattern has been formed in this manner, all of the photoresist is separated by an organic solvent or dry etching (process 10).
Next, on the surface of the polyimide substrate
102
on which the copper wiring pattern has been formed, pieces of epoxy solder resist
110
with a thickness of approximately 25 &mgr;m are formed by printing at positions in which two pieces of polyimide solder resist
111
, which will later be formed, are sandwiched from both sides (process 11). Thereafter, in a manner so as to cover the slits
105
serving as bending portions, pieces of polyimide solder resist
111
, made of the same material as used in process 4, are formed by printing with a thickness of approximately 25 &mgr;m (process 12).
Next, tin plating is applied to the surface of the exposed copper foil by the electroless plating method with a thickness of approximately 0.2 &mgr;m to 0.6 &mgr;m. Further, this tin plating is subjected to a curing process (heating process) so as to prevent the occurrence of whisker (process 13). Whisker refers to a needle-shaped crystal which develops in many kinds of metal when it is subjected to a stress, etc. In particular, whisker tends to develop in tin plating. When whisker develops, short circuits may be exerted between the terminals.
Lastly, the tape carrier
103
, which has been manufactured through the above-mentioned processes, is shipped (process 14).
Moreover, another TCP semiconductor device, which has a construction different from the above-mentioned bicolor flex TCP semiconductor device
101
, has been known. FIG.
9
(
a
) is a plan view showing a schematic construction of a mono-color flex TCP semiconductor device
121
in which only one kind of solder resist is formed on the copper wiring pattern, and FIG.
9
(
b
) is a cross-sectional view taken along line B-B′ in FIG.
9
(
a
).
As illustrated in FIG.
9
(
a
) and FIG.
9
(
b
), pieces of one kind of solder resist
123
are formed on a copper wiring pattern. The solder resist
123
is made of a hard epoxy solder resist having a young's modulus of 200±50 kgf/mm
2
. The mono-color flex TCP semiconductor device
121
can be produced at very low costs since the number of processes for forming solder resist is fewer than that of the bicolor flex TCP semiconductor device
101
. However, because of the use of the solder resist
123
having a greater young's modulus as described above, the mono-color flex TCP semiconductor device
121
is inferior to the bicolor flex TCP semiconductor device
101
in flexibility to bending upon assembly.
FIG. 10
shows manufacturing processes of a tape carrier
122
in the mono-color flex TCP
121
. The manufacturing processes are different from those of the tape carrier
103
in the bicolor flex TCP semiconductor device
101
in that, as described above, only one kind of the hard epoxy solder resist
123
having a young's modulus of 200±50 kgf/mm
2
is formed on the copper wiring pattern, and the other processes are carried out in the same manner as described above; therefore, the description thereof is omitted.
Next, referring to FIG.
12
(
a
), an explanation will be given of a packaging method of the bicolor flex TCP semiconductor devices
101
onto a liquid crystal panel
201
and a PWB (Printed Wiring Board)
202
. In general, for example, in the case of a liquid crystal panel of the 12.1-inch size having 1024 dots×768 dots, upon packaging the bicolor flex TCP semiconductor devices onto the liquid crystal panel, approximately thirteen bicolor flex TCP semiconductor devices are mounted on the source side of the frame edge on one side in the liquid cryst
Asazu Takurou
Iwane Tomohiko
Toyosawa Kenji
Graybill David E.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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