JPH09312372A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a lead frame and the increase of manufacturing costs. SOLUTION: A multiple-connection lead frame 1 is prepared by connecting a number of unit lead frames 1a, each having an inner lead group 9 and an outer lead group 8 held by a lead-group holding frame 2. A multiple-connection assembly 16 is prepared by connecting a number of unit heat sink assemblies 16a, each having a heat sink 22 held by a heat-sink holding frame 17. Each unit heat sink assembly 16a is connected with each unit lead frame 1a by caulk- joining a tongue 13b of a C-shaped hole 13 formed on the lead-group holding frame 2 with a through hole 25 of a step member 24 formed on the heat-sink holding frame. Thus, the lead frames are connected to the multiple-connection heat sink assemblies, which avoids deformation of the lead frames upon assembling after the connection process due to the weight of the heat sinks. Since expensive adhesive tape is not used, the manufacturing costs can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a semiconductor device, and more particularly to a technique for improving heat dissipation performance of a semiconductor integrated circuit device having a surface mount type resin-sealed package. The present invention relates to a resistor effectively used in a semiconductor integrated circuit device (hereinafter referred to as an IC) which is required to be small in size and low in price.

[0002]

2. Description of the Related Art In recent years, ICs are becoming more multifunctional, highly integrated, and faster, and in recent years, ICs equipped with surface mount type resin-sealed packages with a large number of pins have good heat dissipation (heat dissipation). Development of low thermal resistance type packages is desired. Therefore, as an IC provided with a low thermal resistance type package (hereinafter referred to as a low thermal resistance type package IC), a plurality of inner leads are provided around a semiconductor pellet (hereinafter referred to as a pellet) directly bonded to a heat sink. The wire is bridged between each electrode pad of the pellet and each inner lead while being positioned and arranged, and at least a part of the heat sink is resin-molded by the resin sealing body together with the pellet, the inner lead group and the wire. Some are sealed.

When the low thermal resistance type package IC thus constructed is manufactured, it is necessary to keep the positional relationship between the pellet and the inner lead group constant until the resin sealing body is molded. For this reason, it is necessary to mechanically fix the heat sink and the lead frame on which the inner lead group is formed. As a conventional technique for mechanically fixing the lead frame and the heat sink, there are the following fixing methods. The first fixing method is a method in which a caulking convex portion that is provided by embossing on a heat sink is fitted into a through hole formed in the lead frame, and is joined by caulking (so-called eyelet processing). The second fixing method is a method of bonding the lead frame and the heat sink with an adhesive tape.

Incidentally, as an example in which a low thermal resistance type package IC is described, Nikkei BP Co., Ltd. May 3, 1993
Published on 1st "VLSI Packaging Technology (below)" P20
0 to P204 and Japanese Patent Office Unexamined Publication No. 3-28
There is No. 6558.

[0005]

However, the conventional method of fixing the lead frame and the heat sink has the following problems. When a multiple lead frame is used, the balance of the heat sink is lost due to the weight of the heat sink, resulting in defective lead frame deformation. Since the heat sink is heated in the pellet bonding process and the wire bonding process, an expensive heat resistant tape is required as an adhesive tape, which increases the manufacturing cost. Since the caulking processing is performed on the caulking convex portion formed on the heat sink side having a large plate thickness, the caulking processing apparatus becomes large in size, which increases the manufacturing cost.

An object of the present invention is to provide a method of manufacturing a semiconductor device having a low thermal resistance type package which can prevent deformation of a lead frame and increase in manufacturing cost.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

The outline of a typical invention among the inventions disclosed in the present application is as follows.

That is, in a method of manufacturing a semiconductor device having a low thermal resistance type package, a lead frame preparation step of preparing a lead frame in which inner lead groups are held together with outer lead groups in a lead group holding frame, and a heat sink is used as a heat sink. A multiple heat sink assembly preparing step in which a multiple heat sink assembly in which a plurality of unit heat sink assemblies held by a holding frame are arranged is prepared, and the lead frame is attached to each unit heat sink assembly of the multiple heat sink assembly. The heat sink holding frame and the lead group holding frame are mechanically connected to each other to form a combined body.

According to the method of manufacturing a semiconductor device described above,
Since the lead frame is mechanically assembled to the multiple heat sink assembly having high strength, the lead frame is not deformed by the weight of the heat sink in the assembly work after the bonding process. Since it is not necessary to use an expensive adhesive tape, the cost can be reduced.

[0011]

1 is an exploded perspective view showing an outline of a method of manufacturing a low thermal resistance type package IC according to an embodiment of the present invention. FIG. 2 and subsequent drawings are explanatory diagrams for explaining the respective steps.

In this embodiment, the low thermal resistance type package IC is configured as an IC (hereinafter referred to as HQFP IC) equipped with a quad flat package with a heat sink. That is, as shown in FIG. 10, the HQFP / IC 36 has a silicon semiconductor pellet (hereinafter,
It is called pellet. ) 31, a heat sink 22 to which the pellet 31 is bonded, a plurality of inner leads 9 radially arranged on the four sides of the pellet 31, and between each electrode pad 31 a of the pellet 31 and each inner lead 9. A wire 32 having both ends thereof bonded and bridged, an outer lead 8 integrally connected to each inner lead 9, a pellet 31, a part of a heat sink 22, a group of inner leads 9 and a wire 32. Resin encapsulant 34 encapsulating the group with resin
And The resin sealing body 34 is made of a resin having an insulating property and is molded into a square flat plate shape which is sufficiently larger than the pellet 31. The heat sink 22 is made of a material having good thermal conductivity, and is formed in a square flat plate shape smaller than the resin sealing body 34 and larger than the pellet 31. The outer lead 8 is bent in a gull wing shape. The HQFP / IC 36 is manufactured by the manufacturing method described below.

The HQFP according to one embodiment of the present invention will be described below.
-Explain the method of manufacturing an IC. By this explanation, HQF
The details of the configuration of the PIC 36 will be clarified together.

The manufacturing method of the HQFP / IC according to this embodiment includes a lead frame preparation step for preparing the multiple lead frame 1 shown in FIG. A thin plate made of a copper-based material (copper or copper alloy) is used for the multiple lead frame 1 and is integrally formed by an appropriate means such as punching press working or etching working. On the surface of the multiple lead frame 1, a plating film (not shown) for properly performing wire bonding described later is formed of silver (Ag).
It is applied by plating using the above. The multiple lead frame 1 is configured by arranging a plurality of unit lead frames (hereinafter, referred to as lead frames) 1a in a row in one direction. In addition, since the same pattern is repeated in the multiple lead frame 1, the description and illustration are made in principle for one unit.

The lead frame 1a is provided with a lead group holding frame 2 for holding a plurality of inner leads and outer leads. The lead group holding frame 2 is a top rail 3,
The bottom rail 4, the front side rail 5, and the rear side rail 6 are formed by being assembled in a square frame shape. Inside the square frame of the lead frame 1a, a square pellet arranging space 7 having a size corresponding to the pellets is arranged in a similar shape and is virtually formed. A plurality of outer leads 8 are provided on the inner periphery of the top rail 3, the bottom rail 4, the front side rail 5, and the rear side rail 6 at equal intervals on each side and project at right angles. Inner leads 9 are integrally connected to the respective outer leads 8. The inner leads 9 are arranged radially with respect to the voids 7, and the inner tips thereof are substantially at each side of the voids 7. They are aligned in a straight line. A dam bar 10 is installed at a right angle between the outer leads 8 that are adjacent to each other.
The bars 10 are arranged in a straight line in a group of outer leads 8 in a row.

A front side slit 11 is formed in the front side rail 5 so as to extend at a right angle to the top rail 3 and the bottom rail 4, and a rear side slit 12 is formed in the rear side rail 6 in parallel with the front side slit 11. It has been opened. A pair of U-shaped holes 13 are provided between the front side slits 11 and the rear side slits 12 in the front side rails 5 and the rear side rails 6 which are integrated with the adjacent lead frames 1a, 1a, and in the vicinity of the top rails 3. They are opened near the bottom rails 4, respectively. A tongue piece 13b is formed in the U-shaped hole 13 by the cutout hole 13a, and the tongue piece 13b is raised to form a coupling claw described later. The pair of U-shaped holes 13 are formed in the same shape, and both tongue pieces 13b, 13b are symmetrically arranged with the free end sides inside.

Between the front side slit 11 and the rear side slit 12 in the front side rail 5 and the rear side rail 6 in which the adjacent lead frames 1a, 1a are integrated with each other, the two U-shaped holes 13, 13 are formed. A positioning hole 14 is formed in the center. Top rail 3
And the front side rail 5 are orthogonal to each other,
A cutout portion 15 for arranging a sub runner in a transfer molding apparatus described later is cut out.

The method of manufacturing the HQFP / IC according to the present embodiment includes a multiple heat sink assembly preparing step in which the multiple heat sink assembly 16 shown in FIG. 3 is prepared. The multiple heat sink assembly 16 is a plate material made of a copper-based material (copper or copper alloy) and has a thickness that is about four times thicker than that of the multiple lead frame 1, and is integrally formed by punching press processing. ing. The multiple heat sink assembly 16 includes a plurality of unit heat sink assemblies (hereinafter,
It is called a heat sink assembly. ) 16a are arranged side by side in a row in one direction, and each heat sink assembly 1
6a are arranged so as to be aligned with each lead frame 1a of the multiple lead frame 1 described above. In addition, since the same pattern is repeated in the multiple heat sink assembly 16, the description and illustration are made in principle for one unit.

The heat sink assembly 16a includes a heat sink holding frame 17 for holding the heat sink. The heat sink holding frame 17 is the main top rail 1
8, a main bottom rail 19, a main front side rail 20, and a main rear side rail 21, and the four rails are assembled in a square frame shape. The main top rail 18 and the main bottom rail 19 are provided with feed holes 18a and 19a, respectively.

A heat sink 22 formed in a square plate shape is arranged in the square frame, and four corners of the heat sink 22 are suspended by four heat sink suspension bars 23 arranged at the four corners of the square frame. There is. The square of the heat sink 22 is set to be smaller than the resin sealing body and larger than the pellet. On the surface of the pellet bonding side main surface of the heat sink 22,
A plating film (not shown) for appropriately performing pellet bonding described later is applied by a plating process using silver (Ag) or the like.

Main front side rails 20 and main rear side rails 21 of the heat sink assembly 16a.
The main top rail 18 has a pair of step portions 24 for floating the inner leads 9 from the heat sink 22.
And the main bottom rail 19 and are formed by embossing. The upper surfaces of the four step portions 24 are formed in the same plane, and the height of each step portion 24 is set to the minimum value of the dimension that can secure the insulating gap between the inner lead 9 and the heat sink 22. . A through hole 25 for mechanical connection is integrally formed in each step portion 24 by press working,
The through hole 25 can be crimped to the claw portion formed by the tongue piece 13b. Main front side rail 20 and main rear side rail 2
In FIG. 1, each positioning hole 26 is formed in the center of the pair of step portions 24, 24.

At a corner portion where the main top rail 18 and the main front side rail 20 are orthogonal to each other, a projection portion 27 for arranging a sub-runner in a transfer molding apparatus described later is provided so as to project inward at a right angle. The portion 27 corresponds to the cutout portion 15 for disposing the sub runner in the lead frame 1a.
The length of the protruding portion 27 in the direction away from the main top rail 18 is set to correspond to the length of the sub runner, and the lateral width orthogonal to the length direction is set to be larger than the width of the sub runner. There is.

In the joining process, the multiple lead frame 1 and the multiple heat sink assembly 16 having the above-described structure are integrated so that the respective units are overlapped as shown in FIG. Lead frame 1a and heat sink assembly 16
“A” is arranged so that the pellet arranging space 7 and the heat sink 22 are concentric with each other and are vertically stacked. At this time, the U-shaped holes 13 and the positioning holes 14 on the lead frame 1a side are aligned with the step portion 24 and the positioning holes 26 on the heat sink assembly 16a side, respectively. Subsequently, the tongue piece 13b of each U-shaped hole 13 is inserted into the through hole 25 of each step portion 24 and bent so as to engage with the lower end opening edge of the step portion 24 from the inside. This allows
Each claw portion 28 that mechanically connects the lead frame 1a and the heat sink assembly 16a is formed. Since each claw portion 28 sandwiches the opening edge of the through hole 25 of the step portion 24,
The lead frame 1a and the heat sink assembly 16a are mechanically coupled to each other in a superposed state.

In this state, since the pair of claw portions 28, 28 of the main front side rail 20 and the main rear side rail 21 facing each other sandwich the through holes 25, 25 from the opposite sides, respectively. The lead frame 1a and the heat sink assembly 16a are in a state of being able to move relative to each other in the longitudinal direction.
That is, each claw portion 28 and the multiple lead frame 1 and the multiple lead frame 1 can absorb the displacement (expansion and contraction) in the lengthwise direction between the multiple lead frame 1 and the multiple heat sink assembly 16 due to the difference in thermal expansion coefficient or the like. The heat sink assembly 16 is in a mechanically coupled state.

The superposing work, the inserting work and the caulking work can be carried out simultaneously for the plurality of lead frames 1a and the heat sink assembly 16a. Therefore, workability is extremely good.

A combined body 29 in which the lead frame 1a and the heat sink assembly 16a are vertically overlapped and combined with each other.
In the above, the inner end portions of the inner leads 9 in the upper lead frame 1 a are attached to the lower heat sink assembly 1.
The outer peripheral edge portion of the heat sink 22 in 6a is inwardly overlapped by a predetermined dimension when viewed from above, and the step portion 2 is formed on the upper surface of the heat sink 22.
It is in a state of being slightly floated by a height of 4.

A combined body 29 in which the multiple lead frame 1 and the multiple heat sink assembly 16 are combined as described above.
In the pellet bonding process, the pellet bonding work is performed for each heat sink 22, and subsequently, the wire bonding is performed for each pellet and the lead frame 1a in the wire bonding process. At this time, since the combined body 29 is configured in multiples,
These bonding operations are sequentially performed for each unit by pitch-feeding the combined body 29 in the longitudinal direction. At this time, since the main top rails 18 and the main bottom rails 19 of the multiple heat sink assembly 16 are guided while being supported by the guide rails (not shown) of the feeder, the multiple heat sink assembly 16 is guided by its own weight. The multiple lead frame 1 does not bend or deform.

As shown in FIG. 5, the pellet 31
Is formed in a square plate shape smaller than the heat sink 22. The pellet 31 is manufactured by forming an integrated circuit including a semiconductor element group, a wiring circuit and the like in a wafer state in a so-called pre-process in a manufacturing process of a semiconductor device, and then dividing the integrated circuit into a predetermined shape in a dicing process. The pellet 31 is arranged on the upper surface of the heat sink 22 in a similar shape, and is fixed to the heat sink 22 and the pellet 31 by a bonding layer 30 formed of a solder layer. That is, while the solder foil is placed on the upper surface of the heat sink 22 and heated, the pellet 3 is applied to the solder foil.
Solder bonding layer 30 formed by rubbing 1
The pellet 31 is bonded to the heat sink 22 by the.

The pellet bonding may be bonded to the heat sink 22 before the bonding process. As the bonding layer, other than the solder layer, a gold-silicon eutectic layer, a silver paste adhesive layer, or the like can be used. However, it is desirable that the formed bonding layer not be a barrier to heat transfer from the pellet 31 to the heat sink 22. By the way, the solder bonding layer 30
Has a high heat transfer coefficient and is highly flexible, and can absorb mechanical stress acting between the pellet 31 and the heat sink 22.

As shown in FIG. 5, the pellet 31
A wire 32 for electrically connecting the inner lead 9 with each of the inner leads 9 has an electrode pad 31a of the pellet 31 at both ends thereof.
And the tips of the inner leads 9 are respectively bonded and bridged between them. At this time, since the inner tip of the inner lead 9 overlaps with the outer peripheral portion of the heat sink 22, a reaction force against the pressing of the wire 32 is applied to the heat sink 22 during the wire bonding work on the inner lead 9 side. You can ask. Therefore, when performing the wire bonding work, the conventional thermocompression bonding wire bonding apparatus, ultrasonic thermocompression bonding wire bonding apparatus, and ultrasonic wire bonding apparatus can be used.

By the above pellet bonding work and wire bonding work, the integrated circuit built in the pellet 31 is electrically pulled out to the outside through the electrode pad 31a, the bonding wire 32, and the inner lead 9.

The pellet 31 and the wire 3 are attached to the combined body 29.
For the assembly body (hereinafter, referred to as a molding work) 33 shown in FIG. 5 to which 2 is bonded, the transfer molding apparatus 40 shown in FIGS. 6 to 8 is used in the resin encapsulation body molding step. Then, the resin sealing body 34 shown in FIG. 9 is simultaneously molded for each unit.

The transfer molding apparatus 40 shown in FIGS. 6 to 8 is provided with a pair of an upper mold 41 and a lower mold 42 which are clamped together by a cylinder device or the like (not shown). On the mating surface of the upper mold 41 and the lower mold 42, a plurality of sets of upper mold cavity recesses 43a and lower mold cavity recesses 43b are respectively recessed so as to cooperate with each other to form the cavity 43. . However, the illustration and description are made for one unit like the multiple lead frame and multiple heat sink assemblies. The cavity 43 corresponds to a square defined by the dam bar 10 of the lead frame 1 a in the molded work 33. The overall height of the cavity 43 is set to be slightly larger than the overall height of the forming work 33. The depth of the upper mold cavity recess 43a is set to be slightly larger than the protruding height of the wire 32 in the forming work 33 from the lead frame 1a. The depth of the lower mold cavity recess 43b is set to be equal to the height from the lower surface of the heat sink 22 to the upper surface of the step portion 24 in the molding work 33.

A pot 44 is opened on the mating surface of the lower mold 42, and a cylinder device (not shown) is provided in the pot 44.
The plunger 45, which is moved forward and backward, is inserted so that resin (hereinafter, referred to as resin) as a molding material can be fed. Cull 46 is in pot 4 on the mating surface of upper mold 41.
4, the main runner 47 and the sub runner 48, which are arranged at a position facing the No. 4 and are recessed and communicated with each other.
One end of the main runner 47 is connected to the cull 46 and is buried. The other end of the sub-runner 48 is connected to a gate 49 formed in a predetermined corner portion of the upper mold cavity recess 43a, which will be described later. The gate 49 is formed so that a resin 50 described later can be injected into the cavity 43. Has been done.

On the mating surface of the lower die 42, there are four heat sink hanging bar receiving holes 51, which are arranged at four corners of the lower die cavity recess 43b, the depth of which is integrated with the lower die cavity recess 43b. Are so buried that they are continuous. Therefore, the lower mold cavity recess 43b
The corners of each of the corners are notched and open. The planar shape of each heat sink suspension bar accommodation hole 51 is the heat sink suspension bar 23 of the heat sink assembly 16a.
The heat sink suspension bar accommodation holes 51 accommodate the heat sink suspension bars 23, respectively.

Further, a protrusion accommodating hole 52 is provided outside the heat sink hanging bar accommodating hole 51 at a position corresponding to the gate 49 of the upper mold 41 on the mating surface of the lower mold 42, and the depth thereof is the heat sink hanging bar accommodating hole 51. , And a part of it is submerged so as to overlap with the heat sink suspension bar accommodating hole 51. The projecting portion accommodating hole 52 corresponds to the planar shape of the projecting portion 27 of the heat sink assembly 16a,
The protruding portion accommodation hole 52 is configured to accommodate the protruding portion 27. On the mating surface of the lower mold 42, an escape recess 53 is entirely recessed outward from a position appropriately separated from the lower mold cavity recess 43b.

On the other hand, on the mating surface of the upper die 41, four convex portions 54 for backfilling the heat sink suspension bar accommodating holes are arranged and buried in four corner portions of the upper die cavity concave portion 43a. . The planar shape of each convex portion 54 corresponds to the planar shape of the heat sink suspension bar accommodating hole 51, and the height of each convex portion 54 is calculated from the depth of the heat sink suspension bar accommodating hole 51 to the thickness of the heat sink suspension bar 23. It is set to the subtracted value. Therefore, the heat sink suspension bar accommodating hole 51 is backfilled by the convex portion 54 and the heat sink suspension bar 23. That is, the notches formed by the heat sink suspension bar housing holes 51 at the corners of the lower mold cavity recess 43b are closed by the protrusions 54.

Further, on the outside of the heat sink suspension bar accommodation hole backfilling protrusion 54 at a position corresponding to the gate 49 on the mating surface of the upper die 41, there is provided a protrusion receiving hole backfilling protrusion 55. Is provided so as to be continuous with the convex portion 54 for backfilling the heat sink suspension bar housing hole. The planar shape of the convex portion 55 corresponds to the planar shape of the projecting portion 27 of the heat sink assembly 16a. Therefore, the projecting portion 55 cooperates with the projecting portion 27 to refill the projecting portion accommodating hole 52. Has become. The sub-runner 48 is recessed on the mating surface of the protrusion 55 with the protrusion 27, and the gate 49 is recessed on the mating surface of the protrusion 54 continuous with the heat sink suspension bar 23. It is set up. In addition, an escape recess 56 is entirely provided on the mating surface of the upper mold 41 to the outside from a position appropriately separated from the upper mold cavity recess 43a.

Next, the molding process of the resin sealing body 34 on the molding work 33 by the transfer molding device 40 having the above-mentioned structure will be described.

The molding work 33 is loaded in the lower mold 42.
At this time, the heat sink 22 is formed by the lower mold cavity recess 43.
The heat sink suspension bar 2 at each corner is housed in b.
3 and the protrusion 27 are housed in the housing holes 51 and 52, respectively. In this housed state, the heat sink 2
2. The bottom surfaces of the heat sink suspension bar 23 and the protruding portion 27 are in contact with the cavity recess 43b and the bottom surfaces of the housing holes 51 and 52. Also, lead frame 1
The lower surface of a is in contact with the mating surface of the lower mold 42 with the upper mold 41.

Subsequently, the upper die 41 and the lower die 42 are clamped. When the mold is clamped, the area around the dam bar 10 of the lead frame 1a is sandwiched between the upper mold 41 and the lower mold 42 from above and below. The convex portions 54 and 55 that are respectively provided on the mating surface of the upper die 41 are fitted into the respective accommodation holes 51 and 52 that are respectively recessed on the mating surface of the lower die 42, and the convex portions 54 and 55 The lower surface is the accommodation hole 51, 52
Heat sink hanging bar 23 and protrusion 2 housed in
7 is pressed against the upper surface. In this state, the notches formed by the heat sink suspension bar accommodation holes 51 in the respective corners of the lower mold cavity recess 43b are closed by the protrusions 54, so that the upper mold cavity recess 43a and the lower mold cavity recess 43a are closed. The cavity 43 formed by the mold cavity recess 43b is substantially completely sealed.

Then, the resin 50 as a molding material is transferred from the pot 44 to the main runner 47 by the plunger 45.
It is fed to the cavity 43 through the sub-runner 48 and the gate 49 and injected. The resin 50 flowing through the sub-runner 48 flows along the upper surface of the protruding portion 27 of the heat sink assembly 16 a, and passes through the flow path surrounded by the protruding portion 27 and the gate 49 buried in the lower mold 42 to form the cavity 43. Injected inside.

The resin encapsulant 34 is resin-molded by filling the cavity 50 with the resin 50 and thermosetting the resin 50. Resin sealing body 34
After the resin is molded, the upper mold 41 and the lower mold 42 are opened. Simultaneously with this mold opening, the resin sealing body 34 is pushed up and released from the upper mold 41 and the lower mold 42 by ejector pins (not shown). At the time of this mold release, it is desirable to set the ejector pins so that the portion of the heat sink 22 of the molded work 33 is also pushed up.

As described above, in the state where the resin sealing body 34 is resin-molded on the molding work 33 and is released, the molded product 35 shown in FIG. 9 is manufactured.
The pellet 31, the inner lead 9, the wire 32, a part of the heat sink 22, and a part of the four heat sink suspension bars 23 in the molded product 35 are resin-sealed in the resin sealing body 34. There is. That is, one main surface of the heat sink 22 and each heat sink suspension bar 23 is exposed from one main surface of the resin sealing body 34, and the other main surfaces and side surfaces are embedded in the resin sealing body 34. ing.

Although detailed description and illustration are omitted, the runner, the molding trace of the cull, and the flash at the time of resin molding are appropriately removed in the removing step. Then, in the solder plating step, the molded product 35 is coated with a solder plating film (not shown) over the entire exposed surface from the resin sealing body 34. During the solder plating process, the molded product 35 is electrically connected to the multiple lead frame 1 and the multiple heat sink assembly 16, so that the electrolytic plating process can be performed collectively.

Thereafter, the molded product 35 is molded into HQFP in a lead cutting molding process. That is, the dam bar 10 is cut off between the adjacent outer leads 8, 8. The outer leads 8 are separated from the top rails 3, the bottom rails 4, the front side rails 5, and the rear side rails 6, and then bent and formed into a gull wing shape. Each heat sink 22 is separated from the boundary between each heat sink suspension bar 23 and the resin sealing body 34.

The HQFP IC 36 having the above-described structure shown in FIG. 10 is manufactured as described above. The HQFP / IC 36 is mounted on a printed wiring board as shown in FIG.

The printed wiring board 6 shown in FIG.
0 has a main body 61 formed by using an insulating plate material such as glass-impregnated epoxy resin. A plurality of mount pads 62 formed in a rectangular small flat plate shape corresponding to the flat portion of the outer leads 8 are provided on one main surface of the main body 61, and a square corresponding to the row of the outer leads 8 group in the HQFP / IC 36 to be mounted. They are arranged in a frame shape. A heat-dissipating land 63 is disposed on one main surface (referred to as an upper surface) of the main body 61 at the center of a square frame formed by a group of mount pad 62 groups, and the land 63 is an HQF.
It corresponds to the heat sink 22 in the P-IC 36.

The HQFP / IC 36 is the printed wiring board 6
At the time of surface mounting on 0, a solder material (not shown) such as cream solder is applied onto each mount pad 62 and the land 63 by an appropriate means such as a screen printing method. Next, the flat portion of each outer lead 8 of the HQFP / IC 36 and the heat sink 22 are bonded to the mount pad 62 and the land 63 coated with the solder material, respectively. In this state, the solder material is melted by the reflow soldering process and then solidified. Outer lead 8 and mount pad 6 by reflow soldering process
2 and between the heat sink 22 and the land 63, soldering portions 64 and 65 are formed, respectively. In this state, HQFP IC36
Is electrically and mechanically connected to the printed wiring board 60 and is in a surface-mounted state.

When the pellet 31 generates heat during operation in this mounted state, the heat is absorbed in the heat sink 22 because the pellet 31 is directly bonded to the heat sink 22.
Is transferred by heat conduction. Since the heat sink 22 is much thicker than the lead frame and has a large area, it has a very large heat capacity. Therefore, the heat generated by the pellet 31 is pumped to the heat sink 22 with extremely high efficiency, and the pellet 31 is cooled very effectively. Then, the heat directly transmitted to the heat sink 22 passes through the land 63 to the printed wiring board 60.
Is released by heat conduction. Further, the heat generated by the pellet 31 is directly conducted to the heat sink 22.
Is spread throughout. Therefore, the cooling effect of the pellet 31 by the heat sink 22 becomes extremely high.

According to the above embodiment, the following effects can be obtained. (1) Since the pellet 31 is directly bonded to the heat sink 22, the heat generated by the pellet 31 is transferred to the heat sink 22 by heat conduction.
Relatively, the pellet 31 will be cooled very effectively.

(2) The heat sink 22 is the resin sealing body 3
Since it is exposed to the outside of the heat sink 2,
Since the heat pumped by 2 can be released to the outside air, the effect of (1) can be further enhanced.

(3) In the manufacturing process of the HQFP / IC 36, the lead frame 1 a and the heat sink assembly 16
Since the claw portion 28 for mechanically coupling with a is not embedded inside the resin sealing body 34, the claw portion 28 does not restrict the wiring layout of the inner leads 9 inside the resin sealing body 34. . Therefore, even a QFP IC having no heat radiation fin and a heat radiation fin lead for connecting it to the tab can be manufactured as an HQFP IC.

(4) By inserting the tongue piece 13b of the U-shaped hole 13 formed in the thin lead frame into the through hole 25 of the heat sink and bending it to form the mechanical coupling claw portion 28. In comparison with the case where the caulking convex portion formed on the thick heat sink is caulked (so-called eyelet processing) to form the caulking portion for mechanical coupling (so-called eyelet portion), the processing device for coupling is smaller in size. And since it can be simplified, it is possible to prevent an increase in cost of the manufacturing method of the HQFP / IC.

(5) Since the lead frame 1a and the heat sink assembly 16a are joined by mechanical joining, it is possible to omit the use of an expensive adhesive tape to avoid an increase in cost, and at the time of joining. Since there is no gas generation or the like, it is possible to avoid contamination of pellets or the like due to the gas generation or the like.

(6) The pellet 31 is formed by connecting the lead frame 1a to the heat sink assembly 16a.
It is possible to prevent the lead frame 1a from being bent or deformed due to the weight of the heat sink assembly 16a when various operations are performed on the inner lead 9 or when the combined body 29 is transferred.

(7) Since the heat sink assembly 16a is separate from the lead frame 1a before the connection,
The heat sink 22 can be formed thicker than the lead frame 1a, and as a result, the heat dissipation performance can be further improved easily. On the other hand, the lead frame 1a
Since it can be formed thin, the wiring density can be increased.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the shapes of the resin sealing body and the heat sink are not limited to square shapes, but may be rectangular shapes or other quadrilateral shapes. In particular, the heat sink is not limited to a regular quadrangle, but may be circular or polygonal.

The lead frame is not limited to the multiple structure, but may be formed as a single unit and sequentially assembled in the multiple heat sink assembly.

The heat sink is not limited to be partially embedded in the resin sealing body, but may be entirely embedded. When a part of the heat sink exposes one main surface of the resin sealing body, an external heat radiation fin may be attached. In such a case, the outer lead may be bent in the direction of the main surface opposite to the heat sink.

The material for forming the heat sink assembly is not limited to the copper-based material, but other metal materials having good thermal conductivity such as aluminum-based material (aluminum or its alloy) can be used. . In particular, it is desirable to use a material such as silicon carbide (SiC) having excellent thermal conductivity and having a thermal expansion coefficient substantially equal to that of silicon which is a material of the pellet.

In the above-described embodiment, the case where the heat sink is soldered to the land of the printed wiring board has been described, but the heat sink exhibits sufficient heat dissipation performance without soldering.

Further, the heat sink may be used as a conductive member for a ground terminal, a power supply terminal and the like.

In the above description, the QFP, which is the field of application of the invention mainly made by the present inventor, was the background.
-The case of applying to an IC has been described, but the present invention is not limited to this. QFJ-IC, QFI-IC, S
The present invention can be applied to ICs including surface-mounted resin-sealed packages such as OP / ICs, power transistors including those packages, and other electronic devices in general. In particular, the present invention is small and lightweight, has a large number of pins, is low in price, and can be used in a semiconductor device that requires high heat dissipation performance, and can provide excellent effects.

[0066]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

By coupling the lead frame to the multiple heat sink assembly having high mechanical strength, it is possible to prevent the lead frame from being deformed by the weight of the heat sink in the assembly work after the coupling process.
Mechanically coupling the leadframe to the multiple heat sink assembly saves cost by avoiding the use of expensive adhesive tape.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a main part of a method for manufacturing an HQFP / IC according to an embodiment of the present invention.

FIG. 2 shows a multiple lead frame, (a) is a partially omitted plan view, and (b) is a sectional view taken along line bb of (a).

FIG. 3 shows a multiple heat sink assembly, (a)
Is a partially omitted plan view, and (b) is a sectional view taken along line bb of (a).

4A and 4B show a combined body of the multiple lead frame and the multiple heat sink assembly after the joining step, wherein FIG. 4A is a partially omitted plan view, and FIG. 4B is taken along line bb of FIG. FIG.

FIG. 5 shows an assembly after the pellet and wire bonding steps, (a) is a partially omitted plan view, (b).
FIG. 7A is a sectional view taken along line bb of FIG.

6A and 6B show a resin encapsulant molding step, wherein FIG. 6A is a partially omitted front sectional view, and FIG. 6B is a longitudinal sectional view taken along a substantially diagonal line of a cavity.

FIG. 7 shows an upper mold used in a resin encapsulant molding step, (a) is a partially omitted bottom view, and (b) is (b) of (a).
Sectional drawing which follows the b line, (c) is sectional drawing which follows the cc line of (a).

FIG. 8 also shows a lower mold, (a) is a partially omitted plan view, (b) is a sectional view taken along line bb of (a), (c).
FIG. 4A is a cross-sectional view taken along line cc in (a).

9A and 9B show a state after molding of a resin encapsulant, wherein FIG. 9A is a partially omitted plan view, and FIG. 9B is a sectional view taken along line bb of FIG.

FIG. 10 shows a manufactured HQFP / IC,
(A) is a partially cut plan view, (b) is a partially cut front view,
(C) is a cross-sectional view taken along a diagonal line.

FIG. 11 shows a mounted state of the manufactured HQFP / IC, in which (a) is a plan view and (b) is a partially cut front view.

[Description of sign]

1 ... Multiple lead frame, 1a ... Unit lead frame (lead frame), 2 ... Lead group holding frame, 3 ... Top rail, 4 ... Bottom rail, 5 ... Front side rail, 6 ... Rear side rail, 7 ... Pellet placement Void,
8 ... Outer lead, 9 ... Inner lead, 10 ... Dam bar, 11 ... Front slit, 12 ... Rear slit, 13 ... U-shaped hole, 13a ... Cutout hole, 13b ...
Tongue piece, 14 ... Positioning hole, 15 ... Notch portion, 16 ... Multiple heat sink assembly, 16a ... Unit heat sink assembly (heat sink assembly), 17 ... Heat sink holding frame,
18 ... Main top rail, 19 ... Main bottom rail, 20 ... Main front side rail, 21 ... Main rear side rail, 22 ... Heat sink, 23 ... Heat sink suspension bar, 24 ... Step portion, 25 ... Mechanical coupling through hole, 26 ... Positioning hole, 27 ... Projection portion for sub runner arrangement, 28 ... Claw portion, 29 ... Combined body of multiple lead frame and multiple heat sink assembly, 30 ... Bonding layer, 31
... Pellets, 32 ... Wires, 33 ...
Wire-bonded assembly (molding work), 34
… Resin encapsulant, 35… Molded product, 36… HQFP / IC
(Semiconductor device), 40 ... Transfer molding device, 41 ...
Upper mold, 42 ... Lower mold, 43 ... Cavity, 43a ... Upper mold cavity recess, 43b ... Lower mold cavity recess, 4
4 ... Pot, 45 ... Plunger, 46 ... Cull, 47 ... Main runner, 48 ... Sub runner, 49 ... Gate, 50 ...
Resin, 51 ... Heat sink hanging bar accommodating hole, 52 ... Projecting portion accommodating hole, 53 ... Escape recess, 54 ... Heat sink hanging bar accommodating hole backfilling convex portion, 55 ... Projecting portion accommodating hole backfilling convex portion, 56 ... Escape recess, 60 ... Printed wiring board, 61 ... Board body, 62 ... Mount pad, 63 ... Land, 64, 65 ... Soldering section.

Claims (3)

[Claims] 1. A semiconductor pellet is bonded to a heat sink and electrically connected to a plurality of inner leads, and at least a part of the heat sink is resin-sealed with a pellet and an inner lead group by a resin sealing body. The method for manufacturing a semiconductor device includes the following steps: (a) a lead frame preparing step in which a lead frame in which the inner lead group is held in a lead group holding frame together with outer lead groups is prepared; A multiple heat sink assembly preparing step for preparing a multiple heat sink assembly in which a plurality of unit heat sink assemblies in which the heat sinks are held by a heat sink holding frame are arranged;
A coupling step in which the lead frame is mechanically coupled to each unit heat sink assembly of the multiple heat sink assembly between the heat sink holding frame and the lead group holding frame to manufacture a combined body. 2. In the lead frame preparing step,
2. The method of manufacturing a semiconductor device according to claim 1, wherein a multiple lead frame in which a plurality of the lead frames are arranged is prepared corresponding to the arrangement of the unit heat sink assemblies of the multiple heat sink assembly. 3. A U-shaped hole is formed in the lead group holding frame, a through hole is formed in a step portion projecting on the heat sink holding frame, and a tongue piece of the U-shaped hole is formed in the through hole. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the lead frame is coupled to the unit heat sink assembly by the inserted and bent claw portion.