1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
SEMICONDUCTOR DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TECHNICAL FIELD
5 [0001] The present disclosure relates to a semiconductor
device of a resin molded type.
BACKGROUND ART
[0002] As a general resin sealing method for a power
10 module, transfer molding using a molding resin such as epoxy
resin is performed. In conventional transfer molding, inside
a mold, a void due to air entrapment by flow of the molding
resin or gas generated from the molding resin, can occur.
[0003] In addition, a void can also occur in an insulation
15 adhesion member having high thermal conductivity, provided
between a heatsink and a heat dissipation portion of a
semiconductor device. In the case of using a sheet-like
insulation adhesion member, a void occurs between the
insulation adhesion member and a lead frame by air entrapment
20 at the time of pasting. In the case where a liquid
insulation adhesion member is cured and used, a void occurs
due to gas of a solvent separated from an adhesive agent
during a curing process. In any of the cases, the presence
of a void leads to reduction in electric insulation property,
25 moisture-proof property, heat dissipation property, and
3
adhesion property, so that the function of the semiconductor
device is lowered.
[0004] As conventional technology for inhibiting
occurrence of a void at the time of resin sealing, a
5 configuration in which a mold is provided with an air vent
for discharging a void, is known. For example, in a resin
sealing molding apparatus for an electronic component
disclosed in Patent Document 1, a gate is provided at one end
of a cavity formed inside an upper die and a lower die, a
10 resin reservoir part is provided near the other end of the
cavity on the opposite side from the gate, and the resin
reservoir part and the outside communicate with each other
through an air vent.
15 CITATION LIST
PATENT DOCUMENT
[0005] Patent Document 1: Japanese Patent No. 2893085
SUMMARY OF THE INVENTION
20 PROBLEMS TO BE SOLVED BY THE INVENTION
[0006] However, in the method of providing the air vent in
the mold, it is necessary to provide the air vent in advance
at a part where a void is expected to occur, and if a void
occurs at an unexpected part, it is necessary to work the
25 mold again. Thus, there is a problem that time and cost are
4
required for working the mold.
[0007] The present disclosure has been made to solve the
above problem, and an object of the present disclosure is to
provide a semiconductor device that inhibits occurrence of a
5 void in a molding resin or an insulation adhesion member and
has a high function and high reliability, at low cost.
SOLUTION TO THE PROBLEMS
[0008] A semiconductor device according to the present
10 disclosure includes: a lead frame on which a semiconductor
element is mounted and which is made of metal; and a resin
sealing, of the lead frame, at least a surface on which the
semiconductor element is mounted, wherein the lead frame has
a scale-like portion on which scale-shaped projections are
15 consecutively formed, and the scale-like portion is provided
over both sides across a resin boundary portion which is a
boundary between inside and outside of an area sealed by the
resin on the lead frame.
20 EFFECT OF THE INVENTION
[0009] The semiconductor device according to the present
disclosure has the scale-like portion provided over both
sides across the resin boundary portion on the lead frame,
whereby air present inside the resin can be discharged to the
25 outside of the mold during a resin sealing process, thus
5
providing a void inhibition effect. Therefore, it is not
necessary to work an air vent in the mold and a semiconductor
device having a high function and high reliability can be
obtained at low cost.
5 Objects, features, aspects, and effects of the
present disclosure other than the above will become more
apparent from the following detailed description with
reference to the drawings.
10 BRIEF DESCRIPTION OF THE DRAWINGS
[0010] [FIG. 1] FIG. 1 is a sectional view showing a
semiconductor device according to embodiment 1.
[FIG. 2] FIG. 2 is a sectional view showing a
transfer molding process for the semiconductor device
15 according to embodiment 1.
[FIG. 3] FIG. 3 is a top view showing a scale-like
portion in the semiconductor device according to embodiment 1.
[FIG. 4] FIG. 4 is a sectional view showing the
scale-like portion in the semiconductor device according to
20 embodiment 1.
[FIG. 5] FIG. 5 is a sectional view showing the
scale-like portion in the semiconductor device according to
embodiment 1.
[FIG. 6] FIG. 6 shows a scanning electron
25 microscope photograph showing the structure of the scale-like
6
portion in the semiconductor device according to embodiment 1.
[FIG. 7] FIG. 7 shows a scanning electron
microscope photograph showing the structure of the scale-like
portion in the semiconductor device according to embodiment 1.
5 [FIG. 8] FIG. 8 shows an arrangement example of
the scale-like portions in the semiconductor device according
to embodiment 1.
[FIG. 9] FIG. 9 shows an arrangement example of
the scale-like portions in the semiconductor device according
10 to embodiment 1.
[FIG. 10] FIG. 10 shows an arrangement example of
the scale-like portions in the semiconductor device according
to embodiment 1.
[FIG. 11] FIG. 11 shows an arrangement example of
15 the scale-like portions in the semiconductor device according
to embodiment 1.
[FIG. 12] FIG. 12 shows an arrangement example of
the scale-like portions in the semiconductor device according
to embodiment 1.
20 [FIG. 13] FIG. 13 is a top view illustrating the
function of the scale-like portion in the semiconductor
device according to embodiment 1.
[FIG. 14] FIG. 14 is a sectional view illustrating
the function of the scale-like portion in the semiconductor
25 device according to embodiment 1.
7
[FIG. 15] FIG. 15 is a top view illustrating the
function of the scale-like portion in the semiconductor
device according to embodiment 1.
[FIG. 16] FIG. 16 is a sectional view illustrating
5 the function of the scale-like portion in the semiconductor
device according to embodiment 1.
[FIG. 17] FIG. 17 is a sectional view showing a
semiconductor device according to embodiment 2.
[FIG. 18] FIG. 18 is a sectional view showing a
10 first-time transfer molding process for the semiconductor
device according to embodiment 2.
[FIG. 19] FIG. 19 is a sectional view showing a
second-time transfer molding process for the semiconductor
device according to embodiment 2.
15 [FIG. 20] FIG. 20 is a sectional view showing
another semiconductor device according to embodiment 2.
[FIG. 21] FIG. 21 is a sectional view showing a
semiconductor device according to embodiment 3.
[FIG. 22] FIG. 22 is a sectional view showing
20 another semiconductor device according to embodiment 3.
[FIG. 23] FIG. 23 is a sectional view showing
still another semiconductor device according to embodiment 3.
DESCRIPTION OF EMBODIMENTS
25 [0011] Embodiment 1
8
Hereinafter, a semiconductor device according to
embodiment 1 will be described with reference to the drawings.
FIG. 1 is a sectional view showing the semiconductor device
according to embodiment 1, and FIG. 2 is a sectional view
5 showing a transfer molding process for the semiconductor
device according to embodiment 1. A semiconductor device 100
according to embodiment 1 includes a semiconductor element 1,
a lead frame 2, a wire 5 and an inner lead 6 which are wiring
members, an external terminal 7, a molding resin 8, and the
10 like. In the drawings, the same or corresponding parts are
denoted by the same reference characters.
[0012] The semiconductor element 1 is, for example, an
insulated-gate bipolar transistor (IGBT), a metal-oxidesemiconductor
field-effect transistor (MOSFET), an IC chip,
15 an LSI chip, or the like, and is mounted on a mounting
portion of the lead frame 2 via a joining member 4 such as
solder or silver. It is noted that a component (not shown)
other than the semiconductor element 1 is also mounted on the
mounting portion of the lead frame 2.
20 [0013] The lead frame 2 is made from a copper plate or a
copper alloy plate. For the purpose of improving corrosion
resistance and heat resistance, the surface of the lead frame
2 may be coated with a metal plating 2a such as gold, silver,
nickel, or tin, and among these, nickel is often employed.
25 The lead frame 2 has a scale-like portion 3 where scale9
shaped projections are formed consecutively. The scale-like
portion 3 is provided over both sides across a resin boundary
portion 2b which is the boundary between the inside and the
outside of an area sealed by the molding resin 8 on the lead
5 frame 2. The scale-like portion 3 will be described later in
detail.
[0014] An electrode pad of the semiconductor element 1 is
connected to the external terminal 7 via the wire 5 connected
by wire bonding or the inner lead 6 made from a copper plate
10 or a copper alloy plate. The wire 5 and the inner lead 6 may
be replaced with each other. The wire 5 is made from gold,
silver, aluminum, copper, or the like, and has a wire
diameter of about 20 μm to 500 μm.
[0015] Of the lead frame 2, at least a surface on which
15 the semiconductor element 1 is mounted is sealed by the
molding resin 8 which is a thermosetting resin such as epoxy
resin. In the semiconductor device 100 according to
embodiment 1, surfaces on both sides of the lead frame 2 are
sealed by one type of molding resin 8. The molding resin 8
20 formed in an approximately rectangular parallelepiped shape
has a gate breaking trace 8b at a part of a side surface 8a
thereof, and the scale-like portion 3 is provided at the
resin boundary portion 2b on the side opposite to the side
surface 8a having the gate breaking trace 8b.
25 [0016] The transfer molding process for the semiconductor
1 0
device 100 according to embodiment 1 will be described with
reference to FIG. 2. Inside a mold 20, the lead frame 2 on
which the semiconductor element 1 and the like are mounted is
placed, and a melted molding resin is injected into a cavity
5 21 of the mold 20 through a gate 22. The clearance between
the external terminal 7 and the mold 20 is made extremely
narrow so that a large amount of the molding resin 8 will not
leak from the mold 20.
[0017] In the transfer molding process, a part to which
10 the straight distance from the gate breaking trace 8b is
longest in the semiconductor device 100 (in the case of a
rectangular module, a side opposite to the gate breaking
trace 8b) is the last part to be filled with the molding
resin. The molding resin 8 flows into the last filled part,
15 in a state of being high in viscosity and low in wettability.
Therefore, a void due to air entrapment is likely to occur at
the last filled part.
[0018] Therefore, as means for inhibiting a void in the
molding resin 8, the semiconductor device 100 has the scale20
like portion 3 provided across the resin boundary portion 2b
on the lead frame 2. The scale-like portion 3 reaches
abutting surfaces 23 of the upper die and the lower die of
the mold 20. The molding resin flowing on the scale-like
portion 3 forms a discharge path for air owing to
25 recesses/projections on the scale-like portion 3, whereby air
1 1
is discharged through the abutting surfaces 23 of the mold 20.
The discharge path for air formed in the molding resin
disappears when the molding resin is completely cured. Owing
to such an action, the scale-like portion 3 exhibits the same
5 void inhibiting effect as with an air vent, without providing
an air vent in the mold 20.
[0019] The molding resin remaining in the gate 22 is
called a runner 8c. After transfer molding, the
semiconductor device 100 is taken out from the mold 20, and
10 immediately after this, gate breaking is performed to
separate the runner 8c and the semiconductor device 100 from
each other. The gate breaking trace 8b remains at the side
surface 8a of the molding resin 8 after the gate breaking.
[0020] Next, the structure of the scale-like portion 3
15 will be described in detail. FIG. 3 is an enlarged top view
of a part of the scale-like portion, FIG. 4 is a sectional
view cut at a part indicated by A-A in FIG. 3, and FIG. 5 is
a sectional view cut at a part indicated by B-B in FIG. 3.
FIG. 6 and FIG. 7 are scanning electron microscope
20 photographs showing the structure of the scale-like portion.
The scale-like portion 3 is obtained by deforming the surface
of the lead frame 2 into a scaly shape by consecutively
applying a laser beam as a spot on the lead frame 2, and is
formed in a given straight line with a predetermined width W
25 as shown in FIG. 3. In FIG. 3, an arrow denoted by L
1 2
represents the longitudinal direction of the scale-like
portion 3.
[0021] The scale-like portion 3 includes a scale portion
31 on which scale-shaped projections are consecutively
5 provided, and ridge portions 32 provided on both sides of the
scale portion 31 in parallel to the longitudinal direction L
of the scale-like portion 3. As shown in FIG. 7, the ridge
portions 32 are raised to be higher than the scale portion 31
and an area between the two ridge portions 32 has a groove
10 shape. The width W and the height of the scale-like portion
3 can be adjusted using laser output, scan speed, and the
like. The width W of the scale-like portion 3 is set to
about 60 μm to 600 μm, for example. The greater the width W
of the scale-like portion 3 is, the higher the void
15 inhibition effect is.
[0022] Since the scale-like portion 3 is formed through
laser application, the scale-like portion 3 can be easily
formed at any location on the lead frame 2, and the flatness
of the lead frame 2 is not lost during the working. It is
20 also easy to selectively process only a part where the scalelike
portion 3 is to be provided while avoiding a part where
the scale-like portion 3 is not to be provided, e.g., a wire
connection portion or the like. In addition, the scale-like
portion 3 may be provided in a curved line. Further, if the
25 scale-like portion 3 is formed by a unicursal processing
1 3
pattern, the takt time can be shortened and productivity is
improved.
[0023] In the case where it has been found that a void is
likely to occur at an unexpected part of the semiconductor
5 device 100 through investigation using an ultrasonic imaging
device or the like, a long manufacturing period and great
cost are required for modifying the mold or newly creating a
mold. The scale-like portion 3 is very effective for such a
situation, and the scale-like portion 3 only has to be
10 provided at a part where it has been found that a void is
likely to occur. Thus, working for the mold is not needed
and a void can be coped with at low cost.
[0024] Arrangement examples of the scale-like portion 3
and the effects thereof will be described with reference to
15 FIG. 8 to FIG. 12. In FIG. 8, FIG. 9, and FIG. 11, the
scale-like portions 3 are arranged such that the longitudinal
direction L of the scale-like portions 3 is perpendicular to
the resin boundary portion 2b. In FIG. 10 and FIG. 12, the
scale-like portions 3 are arranged such that the longitudinal
20 direction L of the scale-like portions 3 is parallel to the
resin boundary portion 2b. As shown in FIG. 10 and FIG. 12,
in the case where the scale-like portions 3 are arranged such
that the longitudinal direction L of the scale-like portions
3 is parallel to the resin boundary portion 2b, considering
25 positional deviation (about 200 μm at maximum) during laser
1 4
processing, the width W of each scale-like portion 3 is set
to be great (for example, about 600 μm) so as to ensure that
the scale-like portion 3 is formed across the resin boundary
portion 2b.
5 [0025] In the example shown in FIG. 8, a plurality of
(here, four) scale-like portions 3 are provided across the
resin boundary portion 2b at a part to which the straight
distance from the gate breaking trace 8b is longest on the
lead frame 2. In the examples shown in FIG. 9 and FIG. 10, a
10 plurality of scale-like portions 3 are provided at intervals
on the resin boundary portion 2b on the side opposite to the
side surface having the gate breaking trace 8b. Using the
configurations as shown in FIG. 8 to FIG. 10 can inhibit a
void near the last part to be filled with the molding resin.
15 [0026] In the examples shown in FIG. 11 and FIG. 12, a
plurality of scale-like portions 3 are provided at intervals
over the entire areas of the resin boundary portions 2b on
the four sides of the rectangular module. It is noted that,
although the scale-like portions 3 are arranged at equal
20 intervals in FIG. 11, the scale-like portions 3 do not
necessarily need to be arranged at equal intervals, and may
be closely arranged at a part where a void is likely to occur.
Using the configurations as shown in FIG. 11 and FIG. 12 can
cope with voids at every part inside the molding resin 8.
25 [0027] Next, the function of the scale-like portion 3 in
1 5
the semiconductor device 100 will be described with reference
to FIG. 13 to FIG. 16. FIG. 13 is an enlarged top view of a
part of the semiconductor device in the case where the
longitudinal direction of the scale-like portion is
5 perpendicular to the resin boundary portion, and FIG. 14 is a
sectional view cut at a part indicated by C-C in FIG. 13.
FIG. 15 is an enlarged top view of a part of the
semiconductor device in the case where the longitudinal
direction of the scale-like portion is parallel to the resin
10 boundary portion, and FIG. 16 is a sectional view cut at a
part indicated by D-D in FIG. 15.
[0028] In the examples shown in FIG. 13 to FIG. 16, the
surface of the lead frame 2 is coated with the metal plating
2a, and the scale-like portion 3 is formed on the metal
15 plating 2a. Copper which is the material of the lead frame 2
is readily oxidized, and cost is required for management of
the oxidation degree if the lead frame 2 is in an exposed
state. Therefore, if the scale-like portion 3 is formed with
the metal plating 2a remaining on the surface of the lead
20 frame 2, copper oxidation degree management becomes easy. In
addition, laser working is easier for the metal plating 2a
such as nickel, as compared to copper which has a high
reflectance for a laser beam.
[0029] In the case of forming the scale-like portion 3 on
25 the lead frame 2 coated with the metal plating 2a, the scale1
6
like portion 3 may be formed at both of the metal plating 2a
and the lead frame 2 under the metal plating 2a. That is,
the lead frame 2 may be exposed or deformed at the scale-like
portion 3. In any case, a void inhibition effect can be
5 obtained in accordance with the dimensions in width W, height,
and longitudinal direction L of the scale-like portion 3.
[0030] In the transfer molding process, normally, sealing
is made at the abutting surfaces 23 of the upper die and the
lower die of the mold 20 (see FIG. 2) so that resin will not
10 leak. At this time, if the sealing is loose, resin leakage
occurs and unnecessary resin burr is formed. The unnecessary
resin burr adversely affects tie bar cutting, lead forming,
and the like in the subsequent processes, and it becomes
necessary to add a process of removing the resin burr, and
15 therefore this is undesirable.
[0031] On the other hand, as shown in FIG. 13 to FIG. 16,
at the scale-like portion 3 provided for discharging a void,
resin leakage 8d (area represented by dots in the drawings)
occurs within the range of the scale-like portion 3.
20 Therefore, the scale-like portion 3 is provided at such a
location that any functional problem does not arise even when
the resin leakage 8d occurs. The resin leakage amount at the
scale-like portion 3 varies depending on the molding pressure,
the shape of the scale-like portion 3, or the like. However,
25 the resin leakage 8d occurring at the scale-like portion 3 is
1 7
accumulated in the scale-like portion 3 and does not spread
to a part other than the scale-like portion 3. Therefore,
the adverse effect as described above is unlikely to occur.
[0032] As shown in FIG. 13 and FIG. 14, in the case where
5 the longitudinal direction L of the scale-like portion 3 is
perpendicular to the resin boundary portion 2b, the resin
leakage 8d in the longitudinal direction L is inhibited by
the scale portion 31, and the resin leakage 8d in the
direction (transverse direction in FIG. 13) perpendicular to
10 the longitudinal direction L is inhibited by the ridge
portions 32. Thus, the width of the resin leakage 8d can be
kept within a narrow range equal to the width W of the scalelike
portion.
[0033] As shown in FIG. 15 and FIG. 16, in the case where
15 the longitudinal direction L of the scale-like portion 3 is
parallel to the resin boundary portion 2b, the resin leakage
8d in the direction (vertical direction in FIG. 15)
perpendicular to the longitudinal direction L is inhibited by
the ridge portion 32. Thus, the range of the resin leakage
20 8d can be kept within a short distance from the resin
boundary portion 2b to the ridge portion 32. As described
above, since the range of the resin leakage 8d varies
depending on the arrangement relationship between the
longitudinal direction L of the scale-like portion 3 and the
25 resin boundary portion 2b, the arrangement relationship is
1 8
appropriately selected in accordance with the condition
around the part where the scale-like portion 3 is provided.
[0034] In embodiment 1, transfer molding is used for the
resin sealing process. However, the manufacturing method for
5 the semiconductor device 100 is not limited thereto. For
example, injection molding may be used, which can contribute
to cost reduction for resin.
[0035] As described above, according to embodiment 1, the
scale-like portion 3 is provided over both sides across the
10 resin boundary portion 2b on the lead frame 2, whereby air
present inside the molding resin can be discharged to the
outside of the mold 20 in the resin sealing process, thus
providing a void inhibition effect. Since the scale-like
portion 3 is formed by applying a laser beam to the lead
15 frame 2, it is possible to easily provide the scale-like
portion 3 at a part where a void is likely to occur, and
flatness of the lead frame 2 is not lost during working.
Further, working for providing an air vent in the mold is not
needed, and a void can be coped with at low cost. Thus,
20 according to embodiment 1, the semiconductor device 100
having a high function and high reliability can be obtained
at low cost.
[0036] Embodiment 2
FIG. 17 is a sectional view showing a semiconductor
25 device according to embodiment 2, FIG. 18 is a sectional view
1 9
showing a first-time transfer molding process for the
semiconductor device according to embodiment 2, and FIG. 19
is a sectional view showing a second-time transfer molding
process for the semiconductor device according to embodiment
5 2. A semiconductor device 101 according to embodiment 2
includes a first resin (hereinafter, molding resin 8) and a
second resin (hereinafter, second molding resin 9).
[0037] The lead frame 2 of the semiconductor device 101
has a mounting portion 2A on which the semiconductor element
10 1 is mounted, and a heat dissipation portion 2B opposite to
the mounting portion 2A. The mounting portion 2A is sealed
by the molding resin 8, and the heat dissipation portion 2B
is sealed by the second molding resin 9. A scale-like
portion 3b is provided over both sides across a resin
15 boundary portion 2c of an area sealed by the second molding
resin 9 on the heat dissipation portion 2B. On the heat
dissipation portion 2B of the lead frame 2, a thin molding
portion 9d having a thickness of about 0.02 mm to 0.3 mm is
formed. The thin molding portion 9d is joined to a heatsink
20 made of copper or aluminum, via a heat dissipation member
such as grease.
[0038] The molding resin 8 and the second molding resin 9
are both made from thermosetting epoxy resin or the like. It
is noted that, for the second molding resin 9 on the heat
25 dissipation portion 2B side, a high-heat-dissipation resin
2 0
having a higher thermal conductivity than the molding resin 8
is used. The thermal conductivity of the second molding
resin 9 is 3 W/m•K to 12 W/m•K. For the molding resin 8 on
the mounting portion 2A side, a low-stress resin which is a
5 molding resin for a general integrated circuit is used.
[0039] The transfer molding process for the semiconductor
device 101 according to embodiment 2 will be described with
reference to FIG. 18 and FIG. 19. Manufacturing of the
semiconductor device 101 includes two times of transfer
10 molding processes. As shown in FIG. 18, in the first-time
transfer molding process, the lead frame 2 on which the
semiconductor element 1 and the like are mounted is placed
inside a first mold 20A, and the cavity 21 is present on the
mounting portion 2A side of the lead frame 2. A melted
15 molding resin is injected into the cavity 21 of the first
mold 20A through an upper gate 22A.
[0040] The molding resin flows on the mounting portion
side of the lead frame 2 to fill the cavity 21. After the
first-time transfer molding process, the molded product is
20 taken out from the first mold 20A, and immediately after this,
a gate breaking process for separating a runner 8c from the
molded product is performed. After the gate breaking, the
gate breaking trace 8b (see FIG. 17) remains at the side
surface 8a of the molding resin 8.
25 [0041] Subsequently, the second-time transfer molding
2 1
process is performed. For the purpose of enhancing the
adhesion property between the molding resin 8 and the second
molding resin 9, a UV treatment or a plasma treatment may be
performed on the molding resin 8 after the first-time
5 transfer molding process. As shown in FIG. 19, inside a
second mold 20B used in the second-time transfer molding
process, the lead frame 2 of which the mounting portion 2A
side has been sealed through the first-time transfer molding
process is placed, and the cavity 21 is present on the heat
10 dissipation portion 2B side of the lead frame 2.
[0042] The melted second molding resin is injected into
the cavity 21 through a lower gate 22B. The second molding
resin flows into the cavity 21 to form the thin molding
portion 9d and flows to the scale-like portion 3b. The
15 second molding resin flowing on the scale-like portion 3b
forms a discharge path for air owing to recesses/projections
on the scale-like portion 3b, whereby air is discharged
through the abutting surfaces 23 of the second mold 20B.
After the second-time transfer molding process, the molded
20 product is taken out from the second mold 20B, and
immediately after this, a gate breaking process of separating
a runner 9c from the molded product is performed. After the
gate breaking, a gate breaking trace 9b (see FIG. 17) remains
at a side surface 9a of the second molding resin 9.
25 [0043] The thin molding portion 9d covering the heat
2 2
dissipation portion 2B of the lead frame 2 is a thin highheat-
dissipation resin which is excellent in heat dissipation
property, but has a high flow resistance during molding and
thus is poor in fluidity, so that a void due to air
5 entrapment is likely to occur. According to embodiment 2, a
void can be effectively inhibited by providing the scale-like
portion 3b on the heat dissipation portion 2B side, whereby
the semiconductor device 101 which is excellent in heat
dissipation property and has a high function and high
10 reliability can be obtained at low cost. It is noted that,
in embodiment 2, as in a semiconductor device 101A shown in
FIG. 20, a scale-like portion 3a may be provided at the resin
boundary portion 2b of the area sealed by the molding resin 8
on the mounting portion 2A, whereby the same effects as in
15 the above embodiment 1 can be obtained.
[0044] Embodiment 3
In embodiment 3, a semiconductor device having an
insulation adhesion member on the heat dissipation portion 2B
side of the lead frame 2 will be described with reference to
20 FIG. 21 to FIG. 23. In a semiconductor device 102 shown in
FIG. 21, the mounting portion 2A of the lead frame 2 is
sealed by the molding resin 8, and an insulation adhesion
member 10 is provided on the heat dissipation portion 2B. In
a semiconductor device 103 shown in FIG. 22, a heatsink 11 is
25 provided on the heat dissipation portion 2B of the lead frame
2 3
2 with an insulation adhesion member 10 interposed
therebetween.
[0045] The insulation adhesion member 10 is made of mainly
epoxy resin, ceramic, silicone, or the like, and is a high5
thermal-conductivity member having a thermal conductivity of
1 W/m•K to 15 W/m•K. As the insulation adhesion member 10, a
sheet-like member may be used or a liquid insulation adhesion
member may be cured and used. In the case of the sheet-like
insulation adhesion member 10, a void can occur at a pasted
10 surface of the insulation adhesion member 10 due to air
entrapment at the time of pasting. In the case of curing the
liquid insulation adhesion member 10 to be used, a void due
to gas of a solvent or the like separated from the adhesive
agent during the curing process can occur inside the
15 insulation adhesion member 10. Both of the above cases can
cause reduction in electric insulation property, moistureproof
property, heat dissipation property, and adhesion
property. Therefore, a void needs to be inhibited and it is
effective to provide the scale-like portion 3b.
20 [0046] In the examples shown in FIG. 21 and FIG. 22, the
scale-like portion 3a is provided over both sides across the
resin boundary portion 2b on the mounting portion 2A of the
lead frame 2. The function of the scale-like portion 3a is
the same as in the above embodiment 1 and therefore
25 description thereof is omitted. Further, the scale-like
2 4
portion 3b is provided over both sides across an insulation
adhesion member boundary portion 2d which is the boundary
between the inside and the outside of an area covered by the
insulation adhesion member 10 on the heat dissipation portion
5 2B of the lead frame 2. Thus, air entrapped when the sheetlike
insulation adhesion member 10 is pasted or gas of a
solvent separated during the curing process of the liquid
insulation adhesion member 10 is discharged through the
scale-like portion 3b, whereby a void is inhibited.
10 [0047] In a semiconductor device 104 shown in FIG. 23, the
thickness of the lead frame 2 differs between the part where
the semiconductor element 1 is mounted and the part having
the external terminal 7. Therefore, around the heat
dissipation portion 2B of the lead frame 2, the molding resin
15 8 is flush with the heat dissipation portion 2B. Further,
the insulation adhesion member 10 is provided on the heat
dissipation portion 2B and the molding resin 8 being flush
with the heat dissipation portion 2B. In this case, merely
providing the scale-like portion on the heat dissipation
20 portion 2B side of the lead frame 2 cannot obtain a void
inhibition effect.
[0048] Accordingly, in the semiconductor device 104, a
scale-like portion 3c is formed continuously to the end of
the molding resin 8, i.e., the side surface 8a from the heat
25 dissipation portion 2B of the lead frame 2 covered by the
2 5
insulation adhesion member 10. Thus, air inside the
insulation adhesion member 10 or at the pasted surface
thereof can be discharged, whereby a void inhibition effect
is obtained. It is noted that the scale-like portion 3c can
5 be formed by one-time processing without changing the laser
application condition between the heat dissipation portion 2B
of the lead frame 2 and the molding resin 8. Alternatively,
it is also possible to perform processing with different
application conditions for the heat dissipation portion 2B
10 and the molding resin 8 by switching an application program
during one-time processing.
[0049] Further, the heatsink 11 (see FIG. 22) may be
provided on the heat dissipation portion 2B of the
semiconductor device 104 shown in FIG. 23, with the
15 insulation adhesion member 10 interposed therebetween.
Providing the heatsink 11 obtains a semiconductor device
having a small interfacial thermal resistance and excellent
heat dissipation property. It is noted that a glass epoxy
substrate or the like may be provided on the heat dissipation
20 portion 2B of the lead frame 2 with the insulation adhesion
member 10 interposed therebetween.
[0050] According to embodiment 3, even in the case where
the insulation adhesion member 10 is provided on the heat
dissipation portion 2B side of the lead frame 2, it is
25 possible to inhibit a void at the insulation adhesion member
2 6
10 owing to the scale-like portions 3b, 3c, and thus the
semiconductor devices 102, 103, 104 which are excellent in
heat dissipation property and have a high function and high
reliability can be obtained at low cost.
5 [0051] Although the disclosure is described above in terms
of various exemplary embodiments and implementations, it
should be understood that the various features, aspects, and
functionality described in one or more of the individual
embodiments are not limited in their applicability to the
10 particular embodiment with which they are described, but
instead can be applied, alone or in various combinations to
one or more of the embodiments of the disclosure. It is
therefore understood that numerous modifications which have
not been exemplified can be devised without departing from
15 the scope of the present disclosure. For example, at least
one of the constituent components may be modified, added, or
eliminated. At least one of the constituent components
mentioned in at least one of the preferred embodiments may be
selected and combined with the constituent components
20 mentioned in another preferred embodiment.
DESCRIPTION OF THE REFERENCE CHARACTERS
[0052] 1 semiconductor element
2 lead frame
25 2a metal plating
2 7
2b, 2c resin boundary portion
2d insulation adhesion member boundary portion
2A mounting portion
2B heat dissipation portion
5 3, 3a, 3b, 3c scale-like portion
4 joining member
5 wire
6 inner lead
7 external terminal
10 8 molding resin
9 second molding resin
8a, 9a side surface
8b, 9b gate breaking trace
8c, 9c runner
15 8d resin leakage
9d thin molding portion
10 insulation adhesion member
11 heatsink
20 mold
20 20A first mold
20B second mold
21 cavity
22 gate
22A upper gate
25 22B lower gate
2 8
23 abutting surface
31 scale portion
32 ridge portion
100, 101, 101A, 102, 103, 104 semiconductor device
We Claim :
[1] A semiconductor device comprising:
a lead frame on which a semiconductor element is
mounted and which is made of metal; and
a resin sealing, of the lead frame, at least a
surface on which the semiconductor element is mounted,
wherein
the lead frame has a scale-like portion on which
scale-shaped projections are consecutively formed, and
the scale-like portion is provided over both sides
across a resin boundary portion which is a boundary between
inside and outside of an area sealed by the resin on the lead
frame.
[2] The semiconductor device according to claim 1,
wherein
the scale-like portion includes a scale portion on
which the scale-shaped projections are consecutively provided,
and ridge portions provided on both sides of the scale
portion.
[3] The semiconductor device according to claim 1 or 2,
wherein
a plurality of the scale-like portions are provided
at intervals from each other.
[4] The semiconductor device according to any one of
claims 1 to 3, wherein
the scale-like portion is provided in a straight
line, and a longitudinal direction of the scale-like portion
is perpendicular to the resin boundary portion.
[5] The semiconductor device according to any one of
claims 1 to 3, wherein
10 the scale-like portion is provided in a straight
line, and a longitudinal direction of the scale-like portion
is parallel to the resin boundary portion.
[6] The semiconductor device according to any one of
claims 1 to 5, wherein
the resin has a gate breaking trace at a part of a
side surface thereof, and the scale-like portion is provided
at the resin boundary portion to which a straight distance
from the gate breaking trace is longest.
[7] The semiconductor device according to any one of
claims 1 to 5, wherein
the resin has a gate breaking trace at a part of a
side surface thereof, and the scale-like portion is provided
at the resin boundary portion on a side opposite to the side
surface having the gate breaking trace.
[8] The semiconductor device according to any one of
claims 1 to 5, wherein
5 the scale-like portion is provided over an entire
area of the resin boundary portion.
[9] The semiconductor device according to any one of
claims 1 to 8, comprising a metal plating covering a part or
10 an entirety of a surface of the lead frame, wherein
the scale-like portion is formed at the metal
plating.
[10] The semiconductor device according to any one of
claims 1 to 8, comprising a metal plating covering a part or
an entirety of a surface of the lead frame, wherein
the scale-like portion is formed at the metal
plating and the lead frame.
20 [11] The semiconductor device according to any one of
claims 1 to 10, wherein
the lead frame has a mounting portion on which the
semiconductor element is mounted, and a heat dissipation
portion opposite to the mounting portion,
the resin includes a first resin sealing the
3 2
mounting portion and a second resin sealing the heat
dissipation portion, and the heat dissipation portion is
provided with a thin molding portion formed by the second
resin, and
the scale-like portion is provided over both sides
across the resin boundary portion of an area sealed by the
second resin on the heat dissipation portion.
[12] The semiconductor device according to claim 11,
wherein
the scale-like portion is provided over both sides
across the resin boundary portion of an area sealed by the
first resin on the mounting portion.
[13] The semiconductor device according to any one of
claims 1 to 10, wherein
the lead frame has a mounting portion on which the
semiconductor element is mounted, and a heat dissipation
portion opposite to the mounting portion,
the heat dissipation portion is provided with an
insulation adhesion member, and
the scale-like portion is provided over both sides
across an insulation adhesion member boundary portion which
is a boundary between inside and outside of an area covered
by the insulation adhesion member on the lead frame.
3 3
[14] The semiconductor device according to any one of
claims 1 to 10, wherein
the lead frame has a mounting portion on which the
semiconductor element is mounted, and a heat dissipation
portion opposite to the mounting portion,
an insulation adhesion member is provided on the
heat dissipation portion and the resin being flush with the
heat dissipation portion, and
the scale-like portion is provided continuously to
an end of the resin from the heat dissipation portion covered
by the insulation adhesion member.
[15] The semiconductor device according to claim 13 or
14, wherein
a heatsink is provided on the heat dissipation
portion of the lead frame with the insulation adhesion member
interposed therebetween.