Stock material or miscellaneous articles – All metal or with adjacent metals – Width or thickness variation or marginal cuts repeating...
Reexamination Certificate
2003-02-14
2004-05-11
Zimmerman, John J. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Width or thickness variation or marginal cuts repeating...
C428S596000, C428S601000, C072S332000, C072S324000, C072S340000, C072S379200
Reexamination Certificate
active
06733899
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a metal plate and a method of shaping the same and, more particularly, a metal plate that is called a stiffener (a radiating plate and reinforcing plate) employed in a semiconductor device, in which semiconductor chips are packaged in its package, and a method of shaping the same.
2) Description of the Related Art
In recent years, development of the LSI technology as a key technology applied to implement multimedia devices is proceeding steadily toward the higher-speed and larger capacity data transmission. With this development, the higher-density packaging technology of the interface between the LSI and the electronic device is in progress.
As the package that is adapted for the high-density packaging, various packages have been developed. For example, there is the BGA (Ball Grid Array) package in which solder ball terminals are provided to the surface of the package like a grid array in place of lead terminals. Also, there is the TBGA (Tape Ball Grid Array) package that aims at the high performance and multiple pin by using a polyimide tape as the package base material. In some of the TBGA packages, the radiating plate and reinforcing plate, which is called the stiffener, is provided to the back side of the semiconductor chip.
FIG. 1
is a sectional view showing an example of the TBGA package having the stiffener. As shown in
FIG. 1
, in a TBGA package
116
of this package, a concave portion
100
a
is provided in the center portion of one surface of a stiffener
100
made of the metal plate and then a semiconductor chip
108
is fixed to a bottom portion of this concave portion
100
a
via an adhesive layer
110
b
. A polyimide film
102
having Cu wirings
104
thereon is adhered to one surface of the stiffener
100
except the concave portion
100
a
via an adhesive layer
110
a
. A solder resist film
105
having opening portions in its predetermined portions is formed on the Cu wirings
104
, and then solder bumps
106
are connected to the Cu wirings
104
via the opening portions respectively. Then, electrode pads of the semiconductor chip
108
and bonding pads of the Cu wirings
104
are connected mutually via wires
112
. Also, the semiconductor chip
108
, the bonding pads of the Cu wirings
104
, and the wires
112
are sealed with a molding resin
114
.
Further, in case a radiation effect of the package must be enhanced, a plate-fin type heat sink, for example, is adhered/arranged onto an opposite surface to the surface of the stiffener
100
, on which the semiconductor chip
108
is arranged. For this reason, it is preferable that the surface of the stiffener
100
, on which the semiconductor chip
108
is not arranged, should be kept in the flat state.
FIGS. 2A
to
2
C are sectional views showing a stiffener shaping method in the prior art.
FIGS. 3A and 3B
are sectional views showing problems in the stiffener shaping method in the prior art. The stiffener shaping method in the prior art is set forth in Patent Application Publication (KOKAI) Hei 11-102998, for example. More particularly, as shown in
FIG. 2A
, first a die
128
having a metal punch
120
, a clamping metal member
122
, and a supporting table
124
is prepared, and then a metal plate
100
x
serving as the stiffener is positioned between the clamping metal member
122
and the supporting table
124
.
Then, as shown in
FIG. 2B
, the predetermined concave portion
100
a
is formed by moving the metal punch
120
to push it against the metal plate
100
x
. At this time, a convex portion
100
b
that protrudes from the other surface of the metal plate
100
x
is formed simultaneously with the formation of the concave portion
100
a.
Then, as shown in
FIG. 2C
, the convex portion
100
b
is cut by sliding a cutting edge
126
laterally from a connected portion A at which a base portion of the metal plate
100
x
and the convex portion
100
b
are jointed.
In the prior art, the stiffener is formed by shaping the metal plate
100
x
by means of the shaping method described above.
However, in the metal plate shaping method in the prior art, vertical variation in position of the cutting edge
126
is caused during the cutting. Thus, in the case that the cutting edge
126
is deviated upwardly during the cutting, the cutting edge
126
is stuck in the base portion of the metal plate
100
x
, as shown in
FIG. 3A
, when the cutting of the convex portion
100
b
by the cutting edge
126
is completed. Therefore, a cut chip
101
a
is still left in the state that such chip is connected to the metal plate
100
x.
As the countermeasure to this, there is such a method that a cutting start position of the cutting edge
126
is set such that it is previously shifted downwardly and then the convex portion
100
b
is cut. However, in the case of this method, as shown in
FIG. 3B
, the cutting of the convex portion
100
b
by the cutting edge
126
is completed at a side surface portion of the convex portion
100
b
, which is positioned lower than the position of the connected portion A at which the base portion of the metal plate
100
x
and the convex portion
100
b
are jointed. Therefore, a step
101
b
is still left after the convex portion
100
b
is cut.
That is, so-called global step is still left on the cutting surface side of the metal plate
100
x
. Therefore, if the above plate-fin type heat sink is adhered/fixed onto the cutting surface, there is such a possible that disadvantages are caused.
As described above, since a height of the cutting edge
126
is varied vertically during the cutting, it is difficult in the extreme to cut the convex portion
100
b
such that the cut chip
101
a
or the step
101
b
is not left.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a metal plate shaping method capable of shaping a metal plate by forming a concave portion on one surface of the metal plate and then cutting a convex portion that is formed on the other surface by above formation to project therefrom in such a manner that a chip being connected to the metal plate is not left and also the other surface of the metal plate is formed in the substantially flat state, and the metal plate.
The present invention provides a metal plate shaping method which comprises the steps of forming a structure in which a first concave portion is formed in a predetermined portion on one surface of a metal plate, and also a convex portion that protrudes from other surface of the metal plate is formed by formation of the first concave portion, and a second concave portion is formed in a predetermined portion on an outside of a peripheral portion of the convex portion, by shaping a metal plate by means of stamping using a die; and cutting convex portion formed on the other surface of the metal plate.
In the present invention, as shown in
FIGS. 4A and 4B
,
FIGS. 5A and 5B
, and
FIGS. 6A
to
6
C, first a first concave portion
10
a
is formed in a predetermined portion on one surface S
1
of a metal plate
10
by stamping using a die, and also a convex portion
10
b
that protrudes from the other surface S
2
is formed by the formation of the first concave portion
10
a
. At this time, simultaneously a second concave portion
10
c
is formed in a predetermined portion of the other surface S
2
of the metal plate
10
on the outside of the peripheral portion of the convex portion
10
b.
Otherwise, a fine concave portion
10
e
that corresponds to the second concave portion
10
c
may be formed previously on the other surface S
2
of the metal plate
10
. Then, the first concave portion
10
a
may be formed on one surface S
1
of the metal plate
10
, and the convex portion
10
b
that protrudes from the other surface S
2
may be formed.
Then, the convex portion
10
b
formed on the other surface S
2
of the metal plate
10
is cut by a cutting means
26
. At this time, preferably a cutting operation is started from a portion, which is at the same height as the other surface S
2
, of a side surface portion
Iizuka Toshifumi
Nagamine Yoshihisa
Uehara Sumio
Armstrong Kratz Quintos Hanson & Brooks, LLP
Savage Jason L
Shinko Electric Industries Co. Ltd.
Zimmerman John J.
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