Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Insulating material
Reexamination Certificate
1999-09-22
2002-11-19
Jackson, Jerome (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Insulating material
C257S714000
Reexamination Certificate
active
06483185
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power module substrate for use in a power module which dissipates heat, a method of producing the same, and a semiconductor device including the substrate, and more particularly to a power module substrate which is so structured as to be joined directly to a water-cooling type heat sink by means of male screws, a method of producing the same, and a semiconductor device including the substrate.
2. Discussion of the Background
As a power module substrate of the above type, as shown in
FIG. 22
, known is a substrate in which a ceramic substrate
1
is made of AIN, and to the opposite sides of the ceramic substrate
1
, first and second copper plates
2
and
3
are laminated and bonded, and an Ni plating is formed on the upper side of a heat sink
4
made of Cu, and further, the heat sink
4
is laminated and bonded to the second copper sheet
3
through a solder
6
. In the case of a semiconductor device having a semiconductor element
7
mounted onto this substrate, the heating quantity is relatively large. Accordingly, the semiconductor device is joined to a water-cooling type heat sink
8
which transfers the heat outside forcedly by circulating cooling water
8
a
inside thereof. The attachment of the power module substrate to the water-cooling type heat sink
8
is carried out by forming attachment holes
4
a
in the heat sink
4
, and pushing male screws
9
through the attachment holes
4
a
and screwing the male screws in female screws
8
b
formed in the water-cooling type heat sink
8
. In the semiconductor device joined as described above, heat emitted from the semiconductor element and so forth is dissipated outside from the water-cooling type heat sink
8
through the first copper sheet
2
, the ceramic substrate
1
, the second copper sheet
3
, the solder
6
, and the heat sink
4
.
However, in the above-described conventional semiconductor device, the heat transfer route from the semiconductor element
7
or the like to the water-cooling type heat sink
8
is relatively long. In particular, inconveniently, heat from the semiconductor element
7
can not be efficiently transferred to the water-cooling type heat sink
8
, since the second copper sheet
3
is laminated and bonded to the water-cooling type heat sink
8
through the solder
6
having a low thermal conductivity. To solve this problem, it may be proposed that attachment holes
1
a
are formed directly in the ceramic substrate
1
without the heat sink being provided, the male screws
9
are inserted through the attachment holes
1
a
, and screwed in the female screw
8
b
formed in the water-cooling type heat sink
8
, as shown in
FIG. 21
, so that the heat transfer route from the semiconductor element to the water-cooling type heat sink
8
is shortened.
However, there is the problem that it is very difficult to form the attachment holes
1
a
after the ceramic substrate is fired, since the substrate
1
after firing is rigid and brittle. Further, as regards forming the attachment holes
1
a
before firing, and then, firing the ceramic substrate
1
, there is the problem that the pitch of the attachment holes
1
a
can not be exactly produced due to the shrinkage at firing. Even if the attachment holes
1
a
can be accurately formed, there is the danger that the ceramic substrate
1
, which is brittle, may be cracked, caused by the tightening force of the male screws
9
generated when the ceramic substrate
1
is joined to the water-cooling type heat sink
8
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a power module substrate in which the heat transfer route from a semiconductor element to a water-cooling type heat sink is shortened, and thereby, heat from the semiconductor element can be effectively dissipated without the ceramic substrate being damaged, a method of producing the same, and a semiconductor device including the substrate.
According to the present invention, as shown in
FIGS. 1 and 6
, there is provided a power module substrate which comprises a ceramic substrate
11
having a circuit pattern
17
formed on the surface thereof, and a metal frame
12
provided on the periphery of the ceramic substrate
11
and so structured that the ceramic substrate
11
can be joined to a water-cooling type heat sink
27
.
In this power module substrate, the ceramic substrate
11
is joined to the water-cooling type heat sink
27
through the metal frame
12
. Therefore, no external force is applied directly to the ceramic substrate
11
, and breaking of the ceramic substrate
11
, caused by the joining, is prevented. Heat from the semiconductor device mounted onto the circuit pattern
17
can be effectively transferred to the water-cooling type heat sink
27
and dissipated.
Preferably, the ceramic substrate
11
is formed with AIN, Si
3
N
4
, or Al
2
O
3
. When AIN is used as the ceramic substrate
11
, the thermal conductivity and the heat resistance are enhanced. The use of Si
3
N
4
improves the strength and the heat resistance. With the use of Al
2
O
3
, the heat resistance is enhanced.
Preferably, in the above power module substrate, the metal frame
12
has a thickness equal to that of the ceramic substrate
11
or the ceramic substrate
11
having the circuit pattern
17
, and is provided with plural perforations
12
a
formed so as to sandwich the ceramic substrate
11
, and metal thin sheets
13
having through-holes
13
a
in communication with the corresponding perforations
12
a
, and containing contacting portions
13
b
having the undersides thereof contacted to at least a part of the circumferential surface of the ceramic substrate
11
or the circuit pattern
17
are disposed on the surface of the metal frame
12
, whereby the ceramic substrate
11
having the circuit pattern
17
formed thereon and contacted to the undersides of the contacting portions
13
b
can be joined into the water-cooling type heat sink
27
by inserting male screws
26
through the through-holes
13
a
and the perforations
12
a
, and screwing the male screws
26
in female screws
27
a
formed in the water-cooling type heat sink
27
or further inserting the male screws
26
through attachment holes
27
c
formed so as to perforate the water-cooling type heat sink
27
and screwing the male screws in nuts
31
.
As described above, the perforations
12
a
and the through-holes
13
a
are formed in the metal frame
12
and the metal thin sheets
13
bonded to the surface of the metal frame
12
, correspondingly. Accordingly, when the male screws
26
are inserted through the through-holes
13
a
and the perforations
12
a
, and screwed in the female screws
27
a
(
FIG. 2C
) formed in the water-cooling type heat sink
27
, or further inserted through the attachment holes
27
c
formed so as to perforate the water-cooling type heat sink
27
and screwed in nuts
31
(FIG.
6
), the tightening force of the male screws
26
is not applied directly to the ceramic substrate
11
, preventing the breaking of the ceramic substrate
11
, which may be caused by the tightening force of the male screws
26
. Heat from a semiconductor element mounted onto the circuit pattern
17
can be effectively transferred to the water-cooling type heat sink
27
and dissipated.
In the case that the metal frame
12
and the metal thin sheets
13
, disposed on the surface of the metal frame
12
, are made of a material which can be machined relatively easily as compared with the ceramic substrate
11
, and the through-holes
13
a
and the perforations
12
a
are formed in the metal thin sheets
13
and the metal frame
12
, correspondingly, so as to perforate them, attachment holes can be formed in the power module substrate easily and at a high precision attachment pitch.
Also preferably, as shown in
FIG. 8
, a metal frame
62
has a thickness greater than that of the ceramic substrate
11
or the ceramic substrate
11
having the circuit pattern
17
, and is provided with plural perforations
62
Goshi Koichi
Kubo Kazuaki
Nagase Toshiyuki
Nagatomo Yoshiyuki
Shimamura Shoichi
Cruz Lourdes
Jackson Jerome
Mitsubishi Materials Corporation
LandOfFree
Power module substrate, method of producing the same, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power module substrate, method of producing the same, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power module substrate, method of producing the same, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2935168