Semiconductor module and method of manufacturing the same

Details Semiconductor module and method of manufacturing the same Semiconductor module and method of manufacturing the same

2001-03-16

2004-11-02

Cuneo, Kamand (Department: 2827)

Electricity: conductors and insulators

Conduits, cables or conductors

Preformed panel circuit arrangement

C174S261000, C361S760000, C361S783000, C257S678000

Reexamination Certificate

active

06812410

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a semiconductor module and, more particularly, a structure that is able to radiate excellently the heat from the semiconductor element.
In recent years, application of the semiconductor device to the mobile device and the small and high density packaging device makes progress, and thus not only the reduction in size and weight but also the good radiating characteristic is requested. Also, the semiconductor device is mounted onto various substrates, and the semiconductor module containing the substrate is mounted in various devices. As the substrate, there are the ceramic substrate, the printed circuit board, the flexible sheet, the metal substrate, the glass substrate, etc. Here, as the semiconductor module mounted onto the flexible sheet, an example will be explained hereunder. In this case, it is needless to say that these substrates can be employed in embodiments.
A hard disk
100
into which the semiconductor module employing the flexible sheet is mounted is shown in FIG.
25
. For example, this hard disk
100
is described in detail in Nikkei Electronics, 1997, Jun. 16 (No.691), p92-.
This hard disk
100
is packaged into a casing
101
formed of metal, and plural sheet of recording disks
102
are fitted integrally to a spindle motor
103
. A magnetic head
104
is arranged over a surface of the recording disk
102
via a minute clearance respectively. This magnetic head
104
is fitted to a top end of a suspension
106
that is fixed to the top of an arm
105
. Then, an integral structure consisting of the magnetic heads
104
, the suspension
106
, and the arm
105
is fitted to an actuator
107
.
The recording disks
102
must be connected electrically to a read/write amplifier IC
108
to execute the writing/reading via the magnetic heads
104
. Thus, a semiconductor module
110
in which the read/write amplifier IC
108
is mounted onto a flexible sheet
109
is employed. Wirings provided on the flexible sheet
109
are finally connected electrically the magnetic heads
104
. The semiconductor module
110
is called the flexible circuit assembly and is normally abbreviated to FCA.
A connector
111
fitted onto the semiconductor module
110
is exposed from a back surface of the casing
101
. This connector (male or female type)
111
is connected to another connector (female or male type) fitted to a main board
112
. Also, wirings are provided on the main board
112
, and also a driving IC for the spindle motor
103
, a buffer memory, other driving ICs, e.g., ASIC, etc. are mounted.
For example, the recording disk
102
is rotated by the spindle motor
103
at 4500 rpm, and a position of the magnetic head
104
is decided by the actuator
107
. Since this rotating mechanism is tightly sealed by a lid provided to the casing
101
, the heat is filled inevitably in the casing
101
and thus the temperature of the read/write amplifier IC
108
is increased. Therefore, the read/write amplifier IC
108
is positioned on the actuator
107
, the casing
101
, or the like, that has excellent thermal conduction. Also, the rotation of the spindle motor
103
tends to increase such as 5400, 7200, 10000 rpm, and thus this heat radiation becomes important more and more.
In order to explain the above semiconductor module (FCA)
110
further more, a structure of the semiconductor module is shown in FIG.
26
.
FIG. 26A
is a plan view and
FIG. 26B
is a sectional view in which the read/write amplifier IC
108
provided to the top portion is cut out along an A-A line. Since this FCA
110
is folded and then fitted into a part of the casing
101
, a first flexible sheet
109
having a flat shape that can be easily folded is employed.
The connector
111
is fitted to the left end of the FCA
110
to act as a first connector portion. First wirings
121
electrically connected to the connector
111
are stuck to the first flexible sheet
109
and then extended to the right end. Then, the first wirings
121
are electrically connected to the read/write amplifier IC
108
. Also, leads
122
of the read/write amplifier IC
108
connected to the magnetic heads
104
are connected to second wirings
123
. The second wirings
123
are electrically connected to third wirings
126
on the second flexible sheet
124
provided over the arm
105
and the suspension
106
. That is, the right end of the first flexible sheet
109
constitutes a second connecting portion
127
, and is connected to the second flexible sheet
124
there. The first flexible sheet
109
and the second flexible sheet
124
may be integrally formed. In this case, the second wirings
123
and the third wirings
126
are integrally provided.
A supporting member
128
is provided on a back surface of the first flexible sheet
109
on which the read/write amplifier IC
108
is provided. The ceramic substrate or the Al substrate is employed as this supporting member
128
. The heat generated by the read/write amplifier IC
108
can be discharged since the metals exposed in the casing
101
is thermally coupled with the outside via the supporting member
128
.
Then, a connection structure of the read/write amplifier IC
108
and the first flexible sheet
109
will be explained with reference to
FIG. 26B
hereunder.
This first flexible sheet
109
is formed by laminating a first polyimide sheet
130
(referred to as a “first PI sheet” hereinafter), a first adhering layer
131
, a conductive pattern
132
, a second adhering layer
133
, and a second polyimide sheet
134
(referred to as a “second PI sheet” hereinafter) from the bottom. The conductive pattern
132
is sandwiched between the first PI sheet
130
and the second PI sheet
134
.
Also, in order to connect the read/write amplifier IC
108
, an opening portion
135
is formed by removing the second PI sheet
134
and the second adhering layer
133
from a desired area to expose the conductive pattern
132
. Then, as shown in
FIG. 26B
, the read/write amplifier IC
108
is electrically connected via the leads
122
.
In
FIG. 26B
, the heat is radiated from the semiconductor device being packaged with an insulating resin
136
to the outside via the heat radiation path indicated by arrows. More particularly, the semiconductor device in the prior art has such a structure that, since an insulating resin
136
acts as a thermal resistance, the heat generated from the read/write amplifier IC
108
cannot be effectively discharged to the outside in total.
Then, the hard disk will be explained hereunder. The transfer rate of the hard disk in reading/writing needs the frequency of 500 MHz to 1 GHz, or more so as to increase the reading/writing speed of the read/write amplifier IC
108
. Therefore, the wiring path on the flexible sheet connected to the read/write amplifier IC
108
must be reduced and also the increase in the temperature of the read/write amplifier IC
108
must be prevented.
In particular, since the recording disks
102
are rotated at a high speed and are installed in a space of the casing
101
tightly sealed by the lid, the temperature in the casing
101
is increased up to about 70 to 80° C. In contrast, the allowable operating temperature of the normal IC is about 125° C., and the temperature increase of about 45° C. from the internal temperature of 80° C. can be accepted for the read/write amplifier IC
108
. However, as shown in
FIG. 26B
, if the thermal resistance of the semiconductor device per se or the thermal resistance of the FCA is large, the read/write amplifier IC
108
exceeds immediately the allowable operating temperature and cannot exhibit its essential ability. As a result, the semiconductor device or FCA having the excellent radiation characteristic is requested.
In addition, there is such a problem that, since the operating frequency is further increased in the future, the temperature increase of the read/write amplifier IC
108
itself is brought about by the heat generated by the operating process. Although the target operating frequency can be ach

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