U.S. patent application number 11/208385 was filed with the patent office on 2006-03-16 for power module package having excellent heat sink emission capability and method for manufacturing the same.
Invention is credited to Oseob Jeon, Joosang Lee, KeunHyuk Lee, Seungwon Lim.
Application Number | 20060056213 11/208385 |
Document ID | / |
Family ID | 36033722 |
Filed Date | 2006-03-16 |
United States Patent
Application |
20060056213 |
Kind Code |
A1 |
Lee; Joosang ; et
al. |
March 16, 2006 |
Power module package having excellent heat sink emission capability
and method for manufacturing the same
Abstract
A power module package includes a power circuit element, a
control circuit element, a lead frame, an aluminum oxide substrate
having a heat sink and an insulation layer, and a sealing resin.
The control circuit element is electrically connected with the
power circuit element to control chips within the power circuit
element. The lead frame has external connection terminal leads in
its edge and has a first surface to which the power circuit element
and the control circuit element are attached and a second surface
which is used as a heat transmission path. The heat sink is a plate
made of metal such as aluminum and the electrical insulation layer
is formed at least on an upper surface of the heat sink and made of
aluminum oxide. The electrical insulation layer may be formed over
an entire surface of the heat sink. Here, the insulation layer is
attached to the second surface by an adhesive, on a region below
where the power circuit element is attached, to the first surface
of the lead frame. In addition, the sealing resin encloses the
power circuit element and the control circuit element, the lead
frame, and the metal oxide substrate and exposes the external
connection terminals of the lead frame.
Inventors: |
Lee; Joosang; (Bucheon City,
KR) ; Jeon; Oseob; (Bucheon City, KR) ; Lee;
KeunHyuk; (Bucheon City, KR) ; Lim; Seungwon;
(Bucheon City, KR) |
Correspondence
Address: |
Thomas R. FitzGerald
Suite 210
16 E. Main Street
Rochester
NY
14614-1808
US
|
Family ID: |
36033722 |
Appl. No.: |
11/208385 |
Filed: |
August 19, 2005 |
Current U.S.
Class: |
363/144 ;
257/E23.052; 257/E23.092; 257/E25.03; 257/E25.031 |
Current CPC
Class: |
H01L 24/45 20130101;
H01L 24/48 20130101; H01L 2924/00014 20130101; H01L 2924/1305
20130101; H01L 2924/14 20130101; C04B 2237/343 20130101; H01L
2224/48137 20130101; H01L 2924/13055 20130101; C04B 2237/402
20130101; H01L 2224/45124 20130101; H01L 2224/45144 20130101; H01L
2924/181 20130101; H01L 2224/45144 20130101; H01L 2924/181
20130101; H01L 25/162 20130101; H01L 2224/45015 20130101; H01L
2224/45124 20130101; H01L 2924/00014 20130101; H01L 2224/05599
20130101; H01L 2924/2076 20130101; H01L 2924/00 20130101; H01L
2924/00 20130101; H01L 2924/00015 20130101; H01L 2924/00014
20130101; H01L 2924/00 20130101; H01L 2924/2076 20130101; H01L
2924/00 20130101; H01L 2924/00012 20130101; H01L 2924/00 20130101;
H01L 2924/00 20130101; H01L 2924/00015 20130101; H01L 2924/00014
20130101; H01L 2924/00014 20130101; H01L 2224/45144 20130101; H01L
2924/14 20130101; H01L 2224/45015 20130101; H01L 2224/45124
20130101; C04B 37/028 20130101; H01L 23/4334 20130101; H01L
2924/00014 20130101; H01L 2924/01019 20130101; H01L 2224/45015
20130101; H01L 2924/13055 20130101; H01L 2924/01079 20130101; H01L
2224/45124 20130101; H01L 2224/48091 20130101; H01L 2224/48247
20130101; H01L 2224/45015 20130101; H01L 2924/01004 20130101; H01L
2924/01078 20130101; H01L 23/49575 20130101; H01L 2924/1305
20130101; H01L 2224/45144 20130101; H01L 25/165 20130101; H01L
2224/48091 20130101 |
Class at
Publication: |
363/144 |
International
Class: |
H02M 1/00 20060101
H02M001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2004 |
KR |
10-2004-0066176 |
Claims
1. A power module package comprising: a power circuit element
having one or more power semiconductor devices; a control circuit
element electrically connected with the power circuit element, for
controlling the power semiconductor devices within the power
circuit element; a lead frame having external connection terminal
leads with inner ends and outer ends and having a first surface to
which the power circuit element and the control circuit element are
attached and having a second surface opposite the first surface; a
metal/metal oxide substrate having a heat sink of a plate of metal
and an electrical insulation layer formed at least on an upper
surface of the metal plate and comprising an oxide of the metal,
the electrical insulation layer being attached to part or all of a
region of the second surface that corresponds to a region on the
first surface where the power circuit element is attached; and an
encapsulating resin for enclosing the power circuit element, the
control circuit element, the lead frame, and the metal oxide
substrate, and outer end of external connection terminal leads of
the lead frame.
2. The power module package of claim 1, wherein the metal is
aluminum or aluminum alloy.
3. The power module package of claim 1, wherein further comprising
an adhesive for attaching the insulation layer to the lead frame
wherein said adhesive is an epoxy adhesive or a silicone elastomer
adhesive.
4. The power module package of claim 3, wherein the adhesive
comprises a filler having a relatively high thermal conductivity
and an electric insulation property.
5. The power module package of claim 4, wherein the filler is a
nitride, an aluminum oxide, a beryllium oxide, a silicon oxide or a
compound of these oxides.
6. The power module package of claim 1, wherein the lead frame
further comprises a down-set die pad and the power circuit element
and the insulation layer are attached to the down-set die pad.
7. The power module package of claim 1, wherein the insulation
layer is formed on a front side of the heat sink.
8. The power module package of claim 1, wherein the encapsulating
resin exposes a rear surface of the metal/metal oxide
substrate.
9. A power module package comprising: a metal/metal oxide substrate
having a heat sink of a plate of metal and an electrical insulation
layer formed at least on an upper surface of the metal plate and
made of an oxide of the metal; an upper wiring layer having a
wiring pattern and directly attached to the surface of the
insulation layer; external connection terminal leads having one set
of ends connected to an edge of the wiring pattern of the upper
wiring layer; a power circuit element attached to the upper wiring
layer and adjacent the external connection terminals and
electrically connected with the external connection terminal leads
through the wiring pattern; a control circuit element attached to
the upper wiring layer and electrically connected with the power
circuit element and the external connection terminal leads through
the wiring pattern, for controlling chips within the power circuit
element; and an encapsulating resin for enclosing the power circuit
element, the control circuit element, the upper wiring layer, the
metal oxide substrate, and the external connection terminals and
exposing outer ends of the external connection terminal leads.
10. The power module package of claim 9, wherein the metal is
aluminum or aluminum alloy or silicon.
11. The power module package of claim 9, wherein the power circuit
element comprises: a power circuit chip attached to a surface of
the upper wiring layer; and a wire for electrically connecting the
power circuit chip with the wiring pattern.
12. The power module package of claim 9, wherein the control
circuit element comprises: a control chip attached to a surface of
the upper wiring layer; and a wire for electrically connecting the
control circuit chip with the wiring pattern.
13. The power module package of claim 9, wherein the wiring pattern
comprises copper or copper alloy.
14. The power module package of claim 13, wherein the wiring
pattern comprises Cu/Ni, Cu/Au, Cu/Au/Ni.
15. A power module package comprising: a metal/metal oxide
substrate having an electrical insulation layer made of an oxidized
metal plate, a plurality of vias made of non-oxidized metal in said
substrate and formed within the electrical insulation layer, for
passing through the electrical insulation layer, a first surface,
and a second surface; a first wiring layer having a first wiring
pattern connected to first ends of said vias and directly attached
to the first surface of the metal oxide substrate; a second wiring
layer having a second wiring pattern connected to second ends of
said vias and directly attached to the second surface of the metal
oxide substrate; external connection terminal leads each having one
end connected to an edge of the first wiring pattern of the first
wiring layer; a power circuit element attached to a surface of the
second wiring layer and electrically connected with one or more
vias through the second wiring pattern; a control circuit element
attached to a surface of the first wiring layer between the
external connection terminals and electrically connected with one
or more vias and the external connection terminals through the
first wiring pattern, for controlling chips within the power
circuit element; and an encapsulating resin for enclosing the power
circuit element, the control circuit element, the first wiring
layer, the second wiring layer, the metal oxide substrate, and the
external connection terminals and exposing the other end of the
external connection terminals.
16. A power module package comprising: a metal/metal oxide
substrate having an electrical insulation layer made of an oxide of
a plate of metal, a plurality of vias made of non-oxidized metal
and formed within the electrical insulation layer, for passing
through the electrical insulation layer, a first surface, and a
second surface; a first wiring layer having a first wiring pattern
connected to first ends of said vias and directly attached to the
first surface of the metal oxide substrate; a second wiring layer
having a second wiring pattern connected to second ends of said
vias and directly attached to the second surface of the metal oxide
substrate; external connection terminal leads each having one end
connected to an edge of the first wiring pattern of the first
wiring layer; a power circuit element attached to a surface of the
second wiring layer and electrically connected with one or more
vias through the second wiring pattern; a control circuit element
attached to a surface of the first wiring layer between the
external connection terminal leads and electrically connected with
the vias and the external connection terminals through the first
wiring pattern, for controlling chips within the power circuit
element; and an encapsulating resin for enclosing the power circuit
element, the control circuit element, the first wiring layer, the
second wiring layer, the metal oxide substrate, and the external
connection terminals and exposing the other end of the external
connection terminals and part of a surface of the electrical
insulation layer.
17. A power module package comprising: a metal/metal oxide
substrate having a heat sink of a plate of metal and an electrical
insulation layer formed at least on an upper surface of the heat
sink and made of an oxide of the metal; a case having sidewalls
whose bottoms are attached to an edge of the metal oxide substrate
and a cap connected with the sidewalls, for confining a
predetermined space between the sidewalls; an upper wiring layer
having a wiring pattern and directly attached to an upper surface
of the electrical insulation layer between the sidewalls; external
connection terminal leads, each with one end connected with the
wiring pattern of the upper wiring layer and whose other end is
outside of the case; a power circuit element attached to a surface
of the upper wiring layer and electrically connected with the
external connection terminal leads through the wiring pattern; a
control circuit element attached to a surface of the upper wiring
layer and electrically connected with the power circuit element and
the external connection terminal leads through the wiring pattern,
for controlling chips within the power circuit element; and a
silicone resin for filling a space of the case to seal up the power
circuit element, the control circuit element, and the upper wiring
layer.
18. A power module package comprising: a metal/metal oxide
substrate having an electrical insulation layer made of an oxide of
a plate of metal, a plurality of vias made of the metal plate and
formed within the electrical insulation layer, for passing through
the electrical insulation layer, a first surface, and a second
surface; a wiring pattern formed on the first surface of the
metal/metal oxide substrate so as to be connected with first ends
of the vias; an external connection pad formed on the second
surface of the metal oxide substrate so as to be connected with the
second ends of the vias; a semiconductor element electrically
connected with the wiring pattern through a contact bump and
including a semiconductor chip mounted on the first surface of the
metal oxide substrate; and an encapsulating resin formed on the
first surface of the metal/metal oxide substrate so as to enclose
the power chip and to expose the second surface of the metal/metal
oxide substrate.
19. A method for manufacturing a power module package comprising:
attaching a metal/metal oxide substrate to a lead frame having
external connection terminal leads at its edge, wherein said
substrate comprises a heat sink of a plate of metal and an
electrical insulation layer formed at least on an upper surface of
the heat sink and made of an oxide of the metal; attaching a power
circuit chip and a control circuit chip on a first surface of the
lead frame; attaching the lead frame to the metal oxide substrate
so that the insulation layer is on a region of a second surface
that corresponds to superior region on the first surface where the
power circuit element is attached; connecting the power circuit
chip with the control circuit chip using the lead frame by
performing a wire-bonding; and enclosing the power circuit element,
the control circuit element, the lead frame, and the metal oxide
substrate and sealing up those elements using an encapsulating
resin so as to expose external connection terminal leads of the
lead frame.
20. The method of claim 19, wherein the attaching the lead frame to
the metal oxide substrate and the wire-bonding can be performed in
a reverse order.
21. The method of claim 19, wherein an aluminum wire is used to
wire bond the power circuit chip and a gold wire is used to wire
bond the control circuit chip.
22. The method of claim 21, wherein the gold wire bonding is
performed after the aluminum wire bonding is performed.
23. The method of claim 19, wherein the adhesive for attaching the
lead frame to the insulation layer is an epoxy adhesive or a
silicone elastomer adhesive.
24. The method of claim 23, wherein the adhesive comprises a filler
having an excellent thermal conductivity and an electric insulation
property.
25. The method of claim 24, wherein the filler is a nitride, an
aluminum oxide, a beryllium oxide, a silicon oxide or a compound of
these oxides.
26. A method for manufacturing a power module package comprising:
preparing a metal/metal oxide substrate including a heat sink of a
plate made of metal and an electrical insulation layer formed at
least on an upper surface of the heat sink and made of an oxide of
the metal; directly attaching an upper wiring layer having a wiring
pattern on an upper surface of the electrical insulation layer;
attaching one end of external connection terminal leads to an edge
of the wiring pattern of the upper wiring layer; attaching a power
circuit chip and a control circuit chip to the upper wiring layer;
connecting the power circuit chip with the control circuit chip
through the wiring pattern by performing a wire-bonding; and
enclosing the power circuit element, the control circuit element,
the upper wiring layer, the metal oxide substrate, and one end of
the external connection terminals and sealing up these elements
using a sealing resin so as to expose the other end of the external
connection terminals.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of Korean Patent
Application No. 2004-66176, filed on Aug. 21, 2004, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a semiconductor package,
and more particularly, to a power module package having excellent
heat transfer characteristics.
[0004] 2. Description of the Related Art
[0005] Generally, a semiconductor package is manufactured in the
following way: one or more semiconductor chips, such as power
semiconductor devices or integrated circuits, are mounted on a lead
frame or a printed circuit board (PCB), then sealed with an epoxy
molding compound (EMC) for protecting the chips, and the packaged
chips are mounted on a mother board or a PCB for a system. As used
hereinafter the word "chip" means a semiconductor power device or a
semiconductor integrated circuit. A semiconductor power device may
be a single power transistor or one or more power transistors
including one or more transistors for controlling or monitoring
operation of the power transistors.
[0006] While integrated circuits and other electronic apparatus
have long experienced demands for high speed, high capacity, and
high levels of integration, now power devices such as those applied
to automobiles, industrial apparatus, and home appliances are also
confronting similar demands for reduced size, lower weight and low
cost. One way of resolving these demands is to construct a power
module package that contains two or more semiconductor chips in a
single semiconductor package. Such power module packages include
one or more power circuit chips and a control circuit chip. But
power circuit chips generate much more heat than the heat generated
by integrated circuits or control chips. Therefore, effectively
transferring heat from the chips to outside the package is critical
for maintaining high reliability for a long time for such power
modules.
[0007] The U.S. Pat. No. 5,703,399 by Majumdar, entitled
"Semiconductor power module" discloses a power module package
having a heat sink and FIG. 1 herein illustrates a cross-sectional
view of the power module package shown in that patent. Referring to
FIG. 1, the power module package 10 mounts a plurality of
semiconductor chips constituting a power device 9 and a control
device 8 on a lead frame 3 that has a heat sink 1 below the lead
frame 3. The package shown In FIG. 1 has two types of EMC.
Reference numeral "2" represents a "lower EMC" having excellent
thermal conductivity and ordinary electrical insulation and upper
EMC 7 has ordinary thermal conductivity and excellent electrical
insulation. The power circuit chip 4a is mounted on one side of the
lead frame 3 and a control integrated circuit chip 5a is mounted on
the same side of the lead frame 3 and spaced from the power chip
4a. Reference numerals 5b, 6b and 6a represent, respectively, a
resistance component, a gold wire, and an aluminum wire.
[0008] In the power module package 10 having the construction as
described above, heat generated from the power circuit chip 5a is
mostly delivered to the heat sink 1 through lower EMC 2 and then to
outside the power module package 10 through the heat sink 1.
According to the above United States Patent, the heat sink 1 is
made of a metal having high thermal conductivity such as copper or
aluminum.
[0009] When, as in the package 10 where the heat sink 1 is
manufactured using electrically conductive material such as metal,
the lower EMC 2 should satisfy the following two conditions. First,
heat transferred from the power circuit chip 4a should be
transferred quickly to the heat sink 1. Second, the lead frame 3
should be electrically insulated from the heat sink 1.
[0010] To satisfy these conditions, the above United States Patent
uses an EMC with high thermal conductivity for the lower EMC 2.
However, even though the EMC has high thermal conductivity, its
thermal conductivity is 2 W/mK, which is much less than the thermal
conductivity of an aluminum heat sink 1 whose thermal conductivity
is 100 W/mK. In order to provide sufficient electrical insulation
between the heat sink 1 and the lead frame 3, the lower EMC 2
should be at least 500 .mu.m thick or more so that the lead frame
may be insulated from the heat sink 1. If the EMC 2 is much
thinner, then one or both devices 4a, 5a may short circuit to the
heat sink 1 and damage or destroy the power module 10. As such, the
heat sinking ability of the power module package 10 is limited by
the lower EMC 2.
[0011] The power module package 10 uses two EMCs 2 and 7 and each
has different properties. Those skilled in the art understand that
there is often a tradeoff between the electrical insulating ability
of a molding compound and its thermal conductivity. In general, as
one increases, the other decreases. So, in the package 10 that
requires an EMC having high electrical insulation for the upper
EMC, a two-stage molding process is performed. Accordingly, a
manufacturing process of the power module package 10 is complex and
costly. One way of solving the above problem and using only one EMC
is shown in Korean Patent Publication No. 2002-0095053, filed by
the same applicant as the present invention, and entitled "Power
module package having improved heat emission capability and method
thereof." FIG. 2 herein illustrates a schematic, cross-sectional
view of an example of the power module package 100 suggested by the
above Korean Patent Publication.
[0012] Referring to FIG. 2, the power module package 100 mounts a
power circuit element 120 and a control circuit element 130, both
on a first surface 111 of the lead frame 110. The power circuit
element 120 is mounted on a down-set (recessed) die pad 140 of the
lead frame 110. A heat sink 150 is attached to a second surface 112
of the down-set die pad 140 by a high temperature tape 160. In FIG.
2, reference numerals 121, 122, 130, 132, and 170 represent one or
more power circuit chips, an aluminum wire, a control circuit chip,
a gold wire, and an EMC, respectively.
[0013] In the power module package 100, a heat sink 150 made of
ceramic is directly attached to a backside of a down-set die pad
140 by a high temperature tape 160. The high temperature tape 160
can be as thin as about 50 .mu.m. Since the sealing process for the
power module package 100 is performed using only one EMC 170, the
manufacturing process for the package shown in FIG. 2 is simpler
than the process for the package of FIG. 1 and the process to make
the package of FIG. 2 can be automated to further reduce cost.
[0014] However, the ceramic heat sink 150 has a thermal
conductivity of about 24 W/mK, so that its heat sinking ability is
not as good as metal, and further, ceramic is more expensive than
metal. Still further, there is limit on how thin one can make a
ceramic heat sink because ceramic is brittle and will crack if it
is too thin.
[0015] FIG. 3 illustrates a cross-sectional view of another example
of a power module package 200 disclosed in the above-described
Korean Patent Publication No. 2002-0095053. Referring to FIG. 3,
the power module package 200 uses a direct bonded copper (DBC)
substrate 250. The DBC substrate 250 includes: a ceramic plate 251
at the center; an upper copper layer 252 attached to an upper
surface of the ceramic plate 251; and a lower copper layer 253
attached to a lower surface of the ceramic plate 251. One or more
power circuit chips 221 are mounted on the upper copper layer 252
and the lower copper layer 253 acts as a heat sink of the power
module package 200. Reference numerals 210, 222, and 270 represent
a lead frame, an aluminum wire, and EMC, respectively.
[0016] According to the power module package 200, the upper and the
lower copper layers 252 and 253 are directly attached to the
ceramic plate 251 without using EMC (refer to the reference numeral
2 in FIG. 1) or a high temperature adhesive (refer to the reference
numeral 160 in FIG. 2) and the heat dissipation capability of the
heat sink 250 is excellent thanks to high thermal conductivity of
copper. Further, since the copper layers 252 and 253 are attached
to the upper and lower surfaces of the ceramic plate, problems
caused by brittleness of the ceramic are overcome. Still further,
since the encapsulation process for the power module package 200 is
performed in a single transfer molding process using one EMC 270,
its manufacturing process can be simplified and automated to reduce
costs.
[0017] However, the ceramic plate 251 of DBC substrate 250 still
has a lower thermal conductivity than metal and the ceramic plate
251 is still about 635 .mu.m thick so that the manufacturing cost
of the DBC process is high. As such, there is still substantial
room for reducing the size and improving thermal dissipation
ability of the power module package 200.
SUMMARY OF THE INVENTION
[0018] The present invention provides a power module package and a
manufacturing method thereof, with excellent heat dissipation
ability and a simpler and lower cost method of automated
manufacture.
[0019] According to one aspect of the present invention, there is
provided a power module package and a manufacturing method thereof,
capable of reducing manufacturing costs and reducing the thickness
of a substrate or a heat sink so that it has appropriate
characteristics for a power module package. The invention includes
a heat sink that has a core or central element made of metal and a
one or more electrical insulating layers comprising a compound of
the metal and one or more other elements, in particular, an oxide
of the metal on the core or central element.
[0020] According to another aspect of the present invention, there
is provided a power module package, which includes: a power circuit
element; a control circuit element; a lead frame; a metal oxide
substrate; and an EMC. The control circuit element is connected
with the power circuit element to control operation of the power
circuit element. The lead frame has external connection terminal
leads in its edge and has a first surface to which the power
circuit element and the control circuit element are attached and a
second surface used to transfer heat away from the chips. A
metal/metal oxide substrate, e.g., an aluminum/aluminum oxide
substrate acts as a heat sink and an insulation layer. The heat
sink is a plate made of aluminum and the electrical insulating
layer is formed at least on an upper surface of the heat sink and
made of the aluminum oxide. The aluminum oxide layer is an
electrical insulating layer that is affixed to the lead frame by an
adhesive or other suitable means. The aluminum oxide layer covers
all or at least part of the second surface of the lead frame below
a region where the power circuit element is attached. The EMC
encloses the power circuit element, the control circuit element,
the lead frame, and the metal/metal oxide substrate and exposes the
external connection terminal of the lead frame.
[0021] According to further another aspect of the present
invention, there is provided a power module package, which
includes: a metal/metal oxide substrate; an upper wiring layer;
external connection terminal leads; a power circuit element; a
control circuit element; and an EMC. The metal/metal oxide
substrate includes: a heat sink of a plate made of metal, e.g.,
aluminum and an electrical insulation layer formed at least on an
upper surface of the heat sink and made of an oxide of the metal,
in particular, aluminum oxide. An upper wiring layer has a wiring
pattern and is directly attached to an upper surface of the
insulation layer. The external connection terminal leads are
connected at one of their ends with an edge of the wiring pattern
of the upper wiring layer. The power circuit element is attached to
a surface of the upper wiring layer adjacent the leads and is
electrically connected with the external connection terminal leads
by means of bond wires. The control circuit element is attached to
a surface of the upper wiring layer and adjacent other external
connection terminal leads. The control circuit element is
electrically connected with the power circuit element and to the
external connection terminal leads through a wiring bonding pattern
to control the power circuit element(s). The EMC encloses the power
circuit element(s), the control circuit element, the upper wiring
layer, the metal oxide substrate, the inner ends of the external
connection terminals, the internal bond wires, and exposes the
outer ends of the external connection terminals.
[0022] According to still further another aspect of the present
invention, there is provided a power module package, which
includes: a metal/metal oxide substrate; a first wiring layer; a
second wiring layer; external connection terminals; a power circuit
element; a control circuit element; and an EMC. The metal/metal
oxide substrate includes: an electrical insulation layer made of an
oxide on a metal plate. A plurality of vias are made that comprise
the metal within the electrical insulation layer. The vias pass
through the insulation layer. A first wiring layer has a first
wiring pattern connected with one end of the vias and is directly
attached to a first surface of the metal/metal oxide substrate. The
second wiring layer has a second wiring pattern connected to the
other end of the vias and is directly attached to a second surface
of the metal/metal oxide substrate. The external connection
terminal leads are connected at their inner ends to an edge of the
first wiring pattern of the first wiring layer. The power circuit
element is attached to a surface of the second wiring layer and
electrically connected with the via through the second wiring
pattern. The control circuit element is attached to a surface of
the first wiring layer between the external connection terminal
leads and is electrically connected with the via and the external
connection terminal leads through the first wiring pattern to
control chips within the power circuit element. The EMC encloses
the power circuit element, the control circuit element, the first
wiring layer, the second wiring layer, the metal oxide substrate,
and one end of the external connection terminals, exposing the
other end of the external connection terminals.
[0023] According to one aspect of the above-described embodiment,
all or part of one surface of the electrical insulation layer of
the heat sink may be exposed to an outside of the EMC.
[0024] According to another aspect of the present invention, there
is provided a power module package, which includes: a metal/metal
oxide substrate; a case; an upper wiring layer; external connection
terminal leads; a power circuit element; a control circuit element;
and silicone. The metal/metal oxide substrate includes: a heat sink
of a plate made of metal and an electrical insulation layer formed
at least on an upper surface of the heat sink and made of an oxide
of the metal. The case includes: sidewalls with bottom edges
attached to an edge of the metal oxide substrate and a cap
connected between the top edges of the sidewalls so as to define a
predetermined space between the sidewalls. The upper wiring layer
has wiring pattern and is directly attached to an upper surface of
the insulation layer between the sidewalls. The external connection
terminal leads are connected at their inner ends with the wiring
pattern of the upper wiring layer and are exposed at their outer
ends for connection to the rest a device or system. The power
circuit element is attached to a surface of the upper wiring layer
and electrically connected with the external connection terminal
leads through the wiring pattern. The control circuit element is
attached to a surface of the upper wiring layer and electrically
connected with the power circuit element and the external
connection terminal leads through the wiring pattern to control the
power circuit element. A silicone resin fills a space of the case
so as to seal up the power circuit element, the control circuit
element, and the upper wiring layer.
[0025] According to another aspect of the present invention, there
is provided a semiconductor package, which includes: a metal/metal
oxide substrate; a wiring pattern; an external connection pad; a
semiconductor chip; and an EMC. The metal/metal oxide substrate
includes an insulation layer and vias made of an oxide of a
plate-shaped metal and of the vias are made of the metal embedded
in the insulation layer, and passing through the insulation layer.
A wiring pattern is formed on the first surface of the metal oxide
substrate and is connected with one of the ends of the vias. An
external connection pad is formed on the second surface of the
metal/metal oxide substrate and is connected with the other ends of
the vias. The semiconductor chip, e.g., a power circuit chip is
electrically connected with the wiring pattern through a contact
bump and is mounted on the first surface of the metal oxide
substrate. EMC encloses the power chip and the first surface of the
metal oxide substrate but exposes the second surface of the metal
oxide substrate.
[0026] According to another aspect of the present invention, there
is provided a method for manufacturing a power module package, in
which: a lead frame having external connection terminals in its
edge is provided, a heat sink of a plate made of metal is oxidized
to form an electrical insulation layer on at least on an upper
surface of the metal plate; a power circuit chip and a control chip
are attached to a first surface of the lead frame; the lead frame
is attached to the metal oxide substrate so that the insulation
layer is affixed at least on a region of a second surface of the
lead frame that corresponds to a region on the first surface where
the power circuit element is attached; a wire bonding operation is
performed to connect one or more power circuit chips and a control
circuit chip; and encapsulating using an EMC to encapsulate the
power circuit element(s), the control circuit element, the lead
frame, and the metal/metal oxide substrate and expose the external
connection terminal leads.
[0027] According to another aspect of the present invention, there
is provided a method for manufacturing a power module package, in
which: a metal/metal oxide substrate including a heat sink of a
plate made of metal and an insulation layer formed at least on an
upper surface of the metal plate heat sink and made of an oxide of
the metal are prepared for attachment to the lead frame; an upper
wiring layer having a wiring pattern is attached to an upper
surface of the insulation layer; inner ends of external connection
terminal leads are attached to an edge of the wiring pattern of the
upper wiring layer; one or more power circuit chip(s) and a control
circuit chip are attached to a surface of the upper wiring layer
adjacent the inner ends of the external connection terminal leads;
wire bonding is performed to connect the power circuit chip(s) and
the control circuit chip; encapsulating using an EMC to enclose the
power circuit element(s), the control circuit element, the upper
wiring layer, the metal oxide substrate, and one end of the
external connection terminals and expose the other end of the
external connection terminals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0029] FIG. 1 is a schematic, cross-sectional view of one example
of a power module package according to a related art;
[0030] FIG. 2 is a schematic, cross-sectional view of another
example of a power module package according to a related art;
[0031] FIG. 3 is a schematic, cross-sectional view of still another
example of a power module package according to a related art;
[0032] FIG. 4 is a schematic, cross-sectional view of a power
module package according to a first embodiment of the present
invention;
[0033] FIG. 5 is a schematic, cross-sectional view of a power
module package according to a second embodiment of the present
invention;
[0034] FIG. 6 is a schematic, cross-sectional view of a power
module package according to a third embodiment of the present
invention;
[0035] FIG. 7 is a schematic, cross-sectional view of a
modification of a power module package according to a third
embodiment of the present invention;
[0036] FIG. 8 is a schematic, cross-sectional view of a power
module package according to a fifth embodiment of the present
invention;
[0037] FIG. 9 is a schematic, cross-sectional view of one example
of a semiconductor package according to the present invention;
[0038] FIGS. 10A through 10D are cross-sectional views explaining a
method for manufacturing a power module package according to an
embodiment of the present invention; and
[0039] FIG. 11 is a flowchart explaining a method for manufacturing
a power module package according to another embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0040] The present invention will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown. Those of ordinary skill in
the art will understand that other arrangements of power circuit
elements and control circuit elements described in the
specification are possible and the structures of a lead frame and a
heat sink herein are exemplarily and not limited to the specific
arrangements or shapes as illustrated in the drawings.
[0041] FIG. 4 is a schematic, cross-sectional view of a power
module package according to a first embodiment of the present
invention.
[0042] Referring to FIG. 4, a power module package 300 includes: a
lead frame 310; a power circuit element 320; a control circuit
element 330; a metal/metal oxide substrate 350, 355; and an EMC
370.
[0043] The power circuit element 320 includes one or more power
circuit chips 321 with aluminum wire 322 to connect the chips 321
to the leads of the lead frame. The aluminum wire 322 has a
diameter of about 250-500 .mu.m to endure a high rated current. The
control circuit element 330 includes a control circuit chip 331 and
a gold wire 332. The aluminum wires 322 and the gold wires 332
properly connect the power circuit chip(s) 321 and the control
circuit chip 331, respectively to the leads of the lead frame 310
that extend from inside the package 300 to the outside.
[0044] The lead frame 310 has a thickness of about 0.5-1 mm and has
a first surface 311 on which the circuit elements are attached and
a second surface 312 which is opposite to the first surface.
External connection terminal leads are formed at an edge of the
lead frame 310. The external connection terminal leads have inner
ends adjacent to the circuit elements and outer ends that protrude
through the EMC 370. A down-set die pad 340 is formed at a central
portion. The circuit elements 320 and 330 may be attached to a die
pad in the same plane as the leads or to a down-set die pad, such
as die pad 340. The down-set die pad 340 may be positioned on a
symmetric central point or may be formed at an eccentric position.
The power circuit element 320 and the control circuit element 330
are attached to the first surface 311 of the lead frame.
Particularly, the power circuit element 320 which generates most of
the heat is attached to the first surface 311 of the down-set die
pad 340 of the lead frame 310.
[0045] The metal oxide substrate 350, 355 is attached by an
adhesive 360 to the second surface 312 of the lead frame 310 at a
location that corresponds to the region on the first surface where
the power circuit element 320 is attached. As illustrated in FIG.
4, the metal oxide substrate 350 and 355 may be attached to the
second surface 312 of the down-set die pad 340 of the lead frame
310.
[0046] The adhesive 360 is an epoxy adhesive or silicone elastomer.
A filler having excellent thermal conductivity and substantial
electric insulation may be dispersed in the adhesive 360. For the
filler, aluminum nitride (AlN), aluminum oxide (Al.sub.2O.sub.3),
beryllium oxide (BeO), silicon oxide (SiO.sub.2), or combination
thereof may be used. For the adhesive 360, a high temperature tape
or solder for a high temperature may be used, such as Pb/Sn, Sn/Ag,
Pb/Sn/Ag. The adhesive 360 may be formed thin within a thickness of
about 10-20 .mu.m so that thermal conductive efficiency will not
deteriorate but the thickness of the adhesive 360 is not limited to
that thickness.
[0047] The metal/metal oxide substrate 350, 355 includes a heat
sink 350 and an insulation layer 355 made of an oxide of the metal
of the heat sink 350. The heat sink 350 effectively conducts heat
generated from the power circuit element 320 to the outside of the
package 300. For the heat sink 350, material having an excellent
conductivity is used and aluminum having a thermal conductivity of
about 100-130 W/mK is preferred. There is no limitation in
thickness of the heat sink 350 and the thickness can be modified in
various ways depending on a purpose of the power module package
300. Of course, other metal and metal oxide combinations are
possible, e.g. Si and SiO.sub.2.
[0048] The electrical insulation layer 355 should not only
electrically insulate the lead frame 310 from the heat sink but
also guarantee rapid heat transmission to the heat sink 350.
Therefore, the layer 355 may be made of material having an
excellent thermal conductivity and showing a sufficient electrical
insulating ability that it can be made as thin as possible. For
that purpose, the insulation layer 355 is made of an oxide of metal
of the heat sink 350 such as an aluminum oxide. The aluminum oxide
insulation layer 355 has a thermal conductivity of about 20 W/mK,
which is greater than the thermal conductivity the lower EMC 2 (in
FIG. 1) or the adhesive 360. Further, the aluminum oxide insulation
layer 355 has an excellent electric insulation property as does
ceramic material. Therefore, the insulation layer, particularly, an
insulation layer 355a interposed between the lead frame 310 and the
heat sink 350 can display a full electrical insulating effect even
with a thickness of only about 30-50 .mu.m. The thickness of the
insulation layer 355a, however, may change depending on electric
properties of the application apparatus for which the power module
package 300 is used.
[0049] The electrical insulation layer 355 is formed at least on an
upper surface of the heat sink 350. For example, the insulation
layer 355 may be formed on only an upper surface of the heat sink
350 (refer to the reference numeral 355a), or may be formed on only
an upper and a lower surfaces of the heat sink 350 (refer to the
reference numerals 355a and 355b), or may be formed over an entire
surface of the heat sink 350 (refer to the reference numerals 355a,
355b, 355c). The metal/metal oxide substrate 355 may be formed by
anodizing metal 350 that would be used as the heat sink 350. When
the electrical insulation layer 355 on a partial surface of the
heat sink 350, an oxidation operation is performed with the rest
surface of the heat sink 350 masked. When the insulation layer 355
is formed over the entire surface of the heat sink 350, the
manufacturing operation becomes simple and the hardness of the
metal oxide substrate 350 and 355 is increased and thermal property
of the power module package 300 is improved. When forming the
insulation layer 355a on only the upper surface or forming the
insulation layers 355a and 355b on only the upper surface and the
side of the heat sink 350, a heat transmission property of the
power module package 300 is also improved.
[0050] The EMC 370 is intended to maintain an electrical insulation
state between the elements 320 and 330 by isolating the power
circuit element 320 and the control circuit element 330 from each
other and by isolating both of them from the outside. The EMC 370
may be formed using an epoxy molding compound having an excellent
insulating property. In that case, the EMC 370 encloses the power
circuit element 320, the control circuit element 330, the lead
frame 310, and metal oxide substrate 350 and 355, exposing the
outer ends of external connection terminal leads of the lead frame
310. To improve a heat transmission, the EMC 370 may expose one
side of the metal/metal oxide substrate 355 to the outside.
[0051] According to the above-described power module package 300
has an aluminum heat sink which has an excellent heat conductivity
and the aluminum oxide which has relatively good thermal
conductivity and electrically insulates the aluminum 350 from the
lead frame 310.
[0052] FIGS. 10A through 10D are cross-sectional views explaining
an example of a method for manufacturing a power module package 300
according to a first embodiment of the present invention.
[0053] First, referring to FIG. 10A, a lead frame 310 having a
thickness of about 0.5-1.0 mm is prepared. Power circuit chip(s)
321 and a control circuit chip 331 are attached to a surface of the
lead frame 310 through a die attach operation. The power circuit
chip(s) 321 are attached to a down-set die pad portion 340 of the
lead frame 310. The die attach operation can be performed using
solder or using silver epoxy. When solder is used for an adhesive
(not shown), the die attach operation is performed within a
temperature range of about 350-380.degree. C., a pressure range of
about 3-5 kg/cm.sup.2, and in a hydrogen atmosphere. When silver
epoxy is used for an adhesive, the die attach operation is
performed at room temperature and at a pressure range of 1-2
kg/cm.sup.2.
[0054] Next, referring to FIG. 10B, oxidizing one or more surfaces
of an aluminum plate 350 to provide aluminum oxide layers 355a,
355b, 355c. An adhesive 360 such as an epoxy or a silicone
elastomer, including a filler is attached to an upper surface of
the insulation layer 355a.
[0055] Next, referring to FIG. 10C, the aluminum/aluminum oxide
substrate 355 is attached to the lower surface of lead frame 310,
at a position below the location where power circuit chip(s) 321
are attached to the upper surface, using the epoxy 360 including
the filler for an adhesive. The above attach operation may be
performed under a temperature range of about 150-180.degree. C. and
a pressure range of 0.5-1.0 kg/cm.sup.2 for about 3-5 minutes but
is not limited to those specific ranges.
[0056] Referring to FIG. 10D, an aluminum (Al) wire bonding
operation and a gold (Au) wire bonding operation are performed so
that the power circuit chip 321 is electrically connected with the
lead frame 310 and the power circuit chips 321 are electrically
connected each other, and the control circuit chip 330 is
electrically connected with the lead frame 310. Generally, a gold
wire is used as a wire for the control circuit chip 330 and an
aluminum wire is used as a wire for the power circuit chip 321. The
aluminum wire bonding operation is performed using a wedge bonding
method and the gold wire bonding operation is performed using a
ball bonding method. For a swift wire bonding operation, the
aluminum wire 332 is bonded first and subsequently the gold wire
332 is bonded.
[0057] Subsequently, referring to FIG. 4, an encapsulation
operation such as a transfer molding method is performed to enclose
the circuit elements 320 and 330 so that only a lower surface of
the aluminum/aluminum oxide substrate 355 and the outer ends of the
leads may be exposed. After that, general subsequent operations
such as a trimming and a forming are performed.
[0058] FIG. 5 is a cross-sectional view of a power module package
according to a second embodiment of the present invention. The
power module package 400 of the present embodiment is different
from the power module package 200 of the prior art in that it uses
the metal/metal oxide substrate 455 having an upper wiring layer
452 on its upper part, not the DBC substrate (refer to a reference
numeral 250 in FIG. 3) including ceramic. A difference between the
power module package 300 of the above-described first embodiment
and that of the related art will be described in more detail.
[0059] Referring to FIG. 5, the power module package 400 according
to the first embodiment includes: a lead frame 410; one or more
power circuit elements 420; a control circuit element 430; an upper
wiring layer 452; an aluminum/aluminum oxide substrate 455; and an
EMC 470. The power circuit element(s) 420 include power circuit
chips 421 and aluminum/gold wire 422. The control circuit element
430 includes a control circuit chip 431 and aluminum/gold wire 432.
The aluminum/aluminum oxide substrate 450, 455 includes heat sink
450 and an insulation layer 455a formed at least on an upper
surface of the heat sink 450. As illustrated in FIG. 5, the
insulation layer 455a may be formed over an entire surface of the
heat sink 450. See layer 455b (lower) and 455c (sidewalls).
[0060] The upper wiring layer 452 has a wiring pattern for leads
(not shown) and regions between leads are filled with insulating
material. The insulating material may be part of the EMC 470. The
power circuit chip 421 and the control circuit chip 431 are
attached to a surface of the upper wiring layer 452 and the
aluminum/gold wire 422 and the aluminum/gold wire 432 are connected
to the leads of the wiring pattern of the upper wiring layer 452.
The upper wiring layer 452 is directly attached to a surface of the
upper insulating layer 455a of the aluminum oxide layer 455. The
wiring pattern of the upper wiring layer 452 connects the power
circuit elements 420, connects the lead frame 410 with the power
circuit element 420, and electrically connects the power circuit
element with the control circuit element 430.
[0061] In the power module package 400 having the above-described
structure, the heat sink 450 has excellent thermal conductivity and
acts as a heat sink and the aluminum oxide 455a, 455b, 455c is an
excellent thermal conductor and a relatively excellent electric
insulator. Further, the upper wiring layer 452 is directly attached
to a surface of the upper insulation layer 455a of the metal/metal
oxide substrate 455 to that heat transmission is increased even
more.
[0062] FIG. 11 is a flowchart explaining an example of a method for
manufacturing a power module package according to a second
embodiment of the present invention.
[0063] First, aluminum/aluminum oxide substrate 455 is prepared
(S21). The aluminum/aluminum oxide substrate 455 includes the heat
sink 450 and at least one insulation layer 455a made of the
aluminum oxide and formed at least on an upper surface of the heat
sink 450. The insulation layer 455a may be formed over an entire
surface of the heat sink 450. The aluminum/aluminum oxide substrate
455 may be manufactured by performing a general aluminum oxidation
operation known or anodizing. Such anodizing processes are well
known.
[0064] The upper wiring layer 452 is directly formed on the
insulation layer 455a (S22). The upper wiring layer 452 may be
formed on the aluminum oxide layer 455 by a lamination method using
Cu, Cu/Ni, Cu/Au, or Cu/Ni/Au, or a sputtering method using the
above metal. The upper wiring layer 452 has a properly-shaped
wiring pattern for electric connection.
[0065] Subsequently, the external connection terminal lead has its
inner ends attached to an edge of the upper wiring layer 452 (S23).
This attach operation may be performed using an adhesive such as
solder or a thermal tape, laser or spot welding, or using a thermal
fusion method using silver (Ag) or silver (Ag)/stannum (Sn)
plating. Next, the power circuit chip 421 and the control circuit
chip 431 are attached to a surface of the upper wiring layer 452.
The operation for attaching those chips 421 and 431 can be
performed using solder and silver epoxy. For attaching the power
circuit chip 421, solder is used. In that case, the attach
operation is performed within a temperature range of about
330-360.degree. C. For attaching the control circuit chip 431,
silver epoxy is used. In that case, the attach operation is
performed under a room temperature.
[0066] Next, the wire bonding operation is performed (S24). For the
power circuit chip 421, an aluminum wire is used, and for the
control circuit chip 431, a gold wire is used. The wire bonding
operation may be performed in the same way as the wire bonding
operation of the above-described manufacturing operation. As a
result, the chips 421 and 431 are electrically connected with the
wiring pattern of the upper wiring layer 452.
[0067] After that, an encapsulation operation such as a molding
operation is performed using the EMC 470 (S25). In the
encapsulation operation, a transfer molding method may be used.
After general trimming and forming operations are performed (S26),
the power module package 400 as illustrated in FIG. 5 is
completed.
[0068] FIG. 6 is a cross-sectional view of a power module package
according to a third embodiment 500 of the present invention. In
the third embodiment, only differences between package 500 and the
first and the second embodiments will be described in detail.
Referring to FIG. 6, a power module package 500 includes
metal/metal oxide substrate 550, 558, a first wiring layer 552a, a
second wiring layer 552b, external connection terminals 510, a
power circuit element 520, a control circuit element 530; and an
EMC 570. The power module package 500 according to the third
embodiment is characterized by having a metal oxide substrate 550
with vias 558 where the vias 558 pass through an insulation layer
550 to electrically connect the first wiring layer 552a with the
second wiring layer 552b.
[0069] The metal/metal oxide substrate 550, 558 has an aluminum
oxide substrate 550 that has a planar configuration with a
plurality of conductive vias 558 in the substrate 550. The vias 558
pass through the insulation layer 550. The conductive vias 558 may
be formed using metal, e.g., aluminum. The aluminum/aluminum oxide
substrate 550, 558 may be manufactured by masking the via regions
and oxidizing the rest of an aluminum metal plate. The unmasked
portions will remain as aluminum.
[0070] The first wiring layer 552a includes a first wiring pattern
(not shown) and the first wiring pattern is connected to one of the
ends of vias 558. As an alternative, the first wiring pattern could
be electrically connected with a control circuit chip 531 through
external connection terminals of the control circuit chip 531, such
as a bump 532. The control circuit element 530 including the
control circuit chip 531 and the external connection terminals 532
are attached to a surface of the first wiring layer 552a.
[0071] The second wiring layer 552b includes a second wiring
pattern (not shown) and the second wiring pattern is connected with
the other ends of the vias 558. As an alternative, the second
wiring pattern could be electrically connected with the power
circuit chip 521 through an external connection terminal of the
power circuit chip 521, such as an aluminum wire 522. The power
circuit element 520 including the power circuit chip 521 and the
external connection terminal 522 is attached to a surface of the
second wiring layer 552b.
[0072] The external connection terminal 510 of the power module
package 500, such as an external lead, is attached to an edge of
the first wiring layer 552a that is electrically connected with the
first wiring pattern. Alternatively, the external connection
terminal 510 may be attached to an edge of the second wiring layer
552b to be electrically connected with the second wiring
pattern.
[0073] The power module package 500 dissipates less heat than the
power module packages 300 and 400 according to the above-described
first and second embodiments. However, since the chips 521 and 531
are mounted on both sides of the aluminum oxide substrate 550 and
558, module 500 has a smaller size than modules 300 and 400.
Further, since the oxidized aluminum insulation layer 550 has
better heat conductivity than the printed circuit boards (PCB) that
are often used in a power module semiconductor package, it can be
appropriately used as a power module for an application apparatus
of relatively low power.
[0074] FIG. 7 is a cross-sectional view of a power module package
600 according to a fourth embodiment of the present invention. The
package 600 is a modification of the third embodiment, package 500.
Referring to FIG. 7, a power module package 600 includes
metal/metal oxide substrate 650, 658, a first wiring layer 652a, a
second wiring layer 652b, external connection terminals 610, a
power circuit element 620, a control circuit element 630, and an
EMC 670.
[0075] The power module package 600 according to the fourth
embodiment is different from the power module package 500 of the
third embodiment in that part of surface 650a of the metal oxide
substrate 650 is exposed outside of the EMC 670. Although the power
module package 500 according to the third embodiment with the
insulation layer 550 has excellent thermal conductivity, the entire
surface of the insulation layer 550 is enclosed by the EMC 570.
Accordingly, when the power module package 500 according to the
third embodiment is used for a long time, its heat dissipation
deteriorates. On the contrary, because the power module package 600
of the fourth embodiment exposes part 650a of the surface of the
insulation layer 650, its heat dissipation efficiency is better
than the power module package 500 of the third embodiment.
[0076] Referring to FIG. 7, opposite ends of the insulation layer
650 are bent vertically downward so that the left and right parts
650a of the surface of the electrical insulation layer 650 may be
exposed to the outside. However, the illustrated shape of the
electrical insulation layer 650 is a mere example. For example, the
electrical insulation layer 650 may have a bent portion forming an
angle greater or smaller than 90.degree. or may have a straight
portion with no bent portion.
[0077] FIG. 8 is a cross-sectional view of a power module package
700 according to a fifth embodiment of the present invention.
Referring to FIG. 8, the power module package 700 includes
metal/metal oxide substrates 750, 755, a case 780, an upper wiring
layer 752, external connection terminals 710, a power circuit
element 720, a control circuit element 730, and a silicone resin
770. The power module package 700 according to the fifth embodiment
is similar in its structure to the power module package 400 of the
second embodiment except for the following differences.
[0078] Package 700 uses a silicone resin instead of an epoxy resin
as an encapsulating resin 770 because the power module package 700
of the present embodiment is so large in its package area that the
molding operation cannot be performed using the epoxy resin. In
addition, due to the fluent property of silicone resin 770, case
780 is provided so that a frame of the silicone resin may be
maintained. The case 780 can be manufactured using plastics.
[0079] The case 780 includes sidewalls 721-724 and a cap 720 and
the sidewalls are attached at their bottom ends to an edge of the
metal oxide substrates 750 and 755. The cap 720 is connected
between the sidewalls 721-724 to define a predetermined space
between the sidewalls and the predetermined space is filled with
the silicone resin 770. The case 780 may be attached to a surface
of the metal oxide substrates 750 and 755 using an adhesive or may
be fastened to the surface of the metal/metal oxide substrates 750,
755 by inserting a fastening member such as a bolt into locking
holes 782 formed on the metal oxide substrates 750 and 755 and the
case 780, respectively. A plurality of external connection
terminals 710 pass through the case 780 and are electrically
connected to the upper wiring layer 752.
[0080] The power module package 700 may house a high power device,
such as an insulated gate bipolar transistor (IGBT). The power
module package 700 is useful where the power device generates high
heat. Further, in the power module package 700 of the present
embodiment having the aluminum/aluminum oxide substrates 750, 755
overcome the brittleness problem of the power module package having
the DBC substrate including a ceramic plate.
[0081] FIG. 9 is a cross-sectional view of one example of a
semiconductor package 800 according to a sixth embodiment of the
present invention. Referring to FIG. 9, a semiconductor package 800
includes aluminum/aluminum oxide substrate 855, 858, a wiring
pattern 852a, external connection pads 852b, a semiconductor
element 830, and a sealing resin 870.
[0082] The semiconductor package 800 according to the sixth
embodiment is similar in its structure to a flip chip semiconductor
package. One difference is that aluminum/aluminum oxide substrate
855, 858 includes an electrical insulation layer 855 made of a
plate of aluminum oxide and a plurality of vias 858 made of
non-oxidized aluminum that pass through the insulation layer 855.
The aluminum/aluminum oxide substrate 855, 858 can be formed by
masking an aluminum plate and oxidizing the opposed aluminum to
create the vias 858.
[0083] The wiring pattern 852a connected with one end of the vias
858 is formed on a first surface of the aluminum/aluminum oxide
substrate 855, 858. A semiconductor chip 831 is mounted on the
first surface and electrically connected with the wiring pattern
852a through the bump 832. A solder resist 854 may be spread
between the wiring patterns 852a. The external connection pads 852b
connected with the other end of the via 858 is formed on a second
surface of the aluminum/aluminum oxide substrate 855, 858, which is
an opposite side of the first surface. A solder resist may be also
spread between the external connection pads 852b. The external
connection pads 852b are attached to a mother substrate (not shown)
using solder.
[0084] As described above, the semiconductor package having the
aluminum/aluminum oxide substrate has a better heat transmission
compared with the semiconductor package that uses a general
PCB.
[0085] The power module package having the metal oxide substrate
according to the present invention uses metal having an excellent
thermal conductivity as a heat sink and uses an oxide of the metal
as an electrical insulation layer so that the heat sink may be
electrically insulated. The electrical insulation layer made of the
oxide of such metal not only has a better thermal conductivity than
the EMC resin but also shows a sufficient insulation effect in case
of forming a thickness of the insulation layer thin. Therefore,
according to the present invention, it is possible to manufacture
the power module package having an excellent heat emission
property.
[0086] In addition, since the metal/metal oxide substrate provided
to the power module package of the present invention can be
manufactured by oxidizing a metal, the package can be easily
realized and manufacturing cost is reduced. It is not necessary to
perform the two-stage molding operation using two sealing resins
having different properties as was done in the prior art. Instead,
the molding operation is performed using one sealing resin, so that
the manufacturing process is less complex and may be automated.
[0087] According to the present invention, it is possible to use
the aluminum/aluminum oxide substrate having various thickness
depending on power capacity applied to the power module package and
to modify its structure in various ways. Therefore, the power
module package of the present invention can be applied to a package
module having various power capacities.
[0088] Metal substrates with hard oxide metal coatings may be made
by one or more processes. Aluminum is typically anodized to provide
a hard, almost crystalline structure of aluminum oxide on the
surface of the aluminum. The oxide is tightly formed and becomes,
in effect, a barrier to entry of other materials. Anodizing
involves the immersion of the part in an electrolyte solution while
a current is passed through the solution and the part. As oxygen is
formed on the anode (the positive terminal which is the part) it
reacts with the part to form a thin layer of aluminum oxide on the
surface. After anodizing the part can be soaked in dye which
penetrates the still porous (relatively) layer of aluminum oxide.
The final step is sealing the oxide layer by immersion in boiling
water. Further details are found in Electrochemistry Encyclopedia,
http:electrochem.cwru.edu/ed/encycl/art-a02-anodizing.htm. Its
entire disclosure is hereby incorporated by reference.
[0089] Anodizing aluminum or other metals provides a hard, thin
barrier oxide layer that has many advantages. The barrier oxide
layer is usually electrically insulating and has a relatively high
dielectric constant compared to the metal from which it is formed.
Aluminum oxide does not have the high thermal conductivity of
aluminum. However, the rate of heat dissipation depends not only on
the inherent conductivity of a material, but also its thickness.
Since the layer of aluminum oxide needed for electrical insulation
is relatively thin when compared to the aluminum heat sink, the
thin aluminum oxide layer does not materially impair the overall
thermal conductivity of the aluminum/aluminum oxide substrate. In a
typical embodiment of the invention, the ratio of aluminum to
aluminum oxide is about 10 to 1.
[0090] Hard, barrier oxide may also be created with silicon. It is
also well known that silicon will oxidize to provide an oxide layer
on the surface of silicon. This native oxide of silicon is one of
its many advantages in forming integrated circuits. The silicon
oxidation process proceeds in a diffusion-like matter so that
oxygen atoms attach to silicon atoms and thus will take on the
corresponding structure of the silicon substrate. If the substrate
is crystalline or polycrystalline, the silicon dioxide layer will
have a similar surface. Silicon dioxide is a common dielectric in
semiconductor applications.
[0091] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *