JP2003086616A - Method of manufacturing electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately and simultaneously cut unnecessary resin parts when a lead frame is cut in the manufacturing method of an electronic device where an installation part having a heat sink on which a heater element is loaded and the lead frame is sealed by resin in a state where the end part of the heat sink is exposed. SOLUTION: A mold is provided with a space 110 for sealing device, an accumulation part 120 accumulating resin 50 outside the end 21 exposed from resin 50 in the heat sink 20 and a connecting part 130 connecting the space 110 and the accumulation part 120 inside. The installation part is arranged in the mold, and resin 50 is packed and cured. The guide frame 33 of the lead frame 30 is cut and a connection resin 53 formed by the connection part 130 of the mold is cut. The mold where the width (t) of the connection part 130 in a direction orthogonal to the cutting direction of the connection resin part 53 is 0.05 mm to 0.15 mm is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device in which a device portion including a heat sink on which a heating element is mounted and a lead frame is sealed so as to be wrapped with resin in a state where an end portion of the heat sink is exposed. Manufacturing method.

[0002]

2. Description of the Related Art FIG. 8 shows a schematic sectional structure of a general electronic device of this type. A device section 40 including a heat sink 20 on which a heat generating element 10 such as a power IC is mounted and a lead frame 30 is sealed so as to be wrapped with a resin 50 in a state where an end 21 of the heat sink 20 is exposed. Here, the heating element 10 and the lead portion (inner lead) 34 of the lead frame 30 are formed of the wire 6 such as Al or Au.
It is electrically connected at 0.

The end 21 of the heat sink 20 is exposed from the resin 50 for attaching a heat radiating member. In FIG. 8, a radiating fin (heat radiating member) 70 is attached to the end 21 by a screw 71 or the like. The heat dissipation of the heat sink 20 is improved.

This electronic device is generally manufactured by the method shown in FIG. The device unit 40 is arranged inside the molding die 900 for resin filling. At this time, the guide frame 33, which will be divided later, is attached to the lead frame 30 by the device unit 40.
Exists on the outer periphery of the end 21 of the heat sink 20.

By filling the resin mold 50 with the resin 50 and curing the resin mold 50, the device 40 is sealed with the resin 50 and the end 21 of the heat sink 20 is exposed from the resin 50. . In this way, after resin molding, the guide frame 3 in the lead frame 30
An electronic device is completed by cutting 3 and cutting the outer lead into a predetermined length.

[0006]

By the way, in the conventional manufacturing method shown in FIG. 9 described above, when resin molding is performed, a thin resin film (resin film) is formed in the gap between the guide frame 33 and the end portion 21 of the heat sink 20. A thin film 51) is formed.
When the guide frame 33 is cut, the resin thin film 51 located at the guide frame cutting portion is also cut, but since it is thin, it does not bend well and is likely to remain as burrs at the end 21 of the heat sink 20. .

In order to solve such a problem, the present inventor thought that the rigidity of the resin thin film located at the cut portion of the guide frame should be increased to make it easier to cut. Then, as a result of the examination, it was decided to use the molding die 100 having the configuration as shown in FIGS.

Here, FIG. 1 is a schematic cross-sectional view of the molding die 100 including the apparatus portion 40 and the resin 50. Also, FIG.
2 is a schematic plan view as seen from above in FIG. 1, mainly showing the shape of the device section 40 including the resin 50. FIG. That is, in FIG. 2, the shape of the inside of the molding die 100 is shown by the shape of the resin 50.

In FIG. 2, in order to identify the positional relationship between the respective parts, the resin 50 is hatched with a wide pitch, the lead frame 30 including the guide frame 33 is hatched with a narrow pitch, and the heating element 10 is shown with a broken line. The wire 60 is partially omitted. Further, the section taken along the dashed-dotted line AA in FIG. 2 is FIG. Furthermore, FIG.
FIG. 3 is a schematic cross-sectional view taken along the dashed line BB in FIG. 2.

As shown in FIGS. 1 to 3, inside the molding die 100, a space portion 110 filled with the resin 50 for sealing the device portion 40 is provided as in the conventional case. Here, inside the molding die 100, outside the end 21 of the heat sink 20 exposed from the resin 40, a reservoir 120 as a space for the resin 40 is positioned adjacent to the end 21. As shown in FIGS. 2 and 3, a communication portion 130 that communicates the space portion 110 and the reservoir portion 120 is provided.

Specifically, the reservoir 120 is a space in which the gap between the end 21 of the heat sink 20 and the guide frame 33 is larger than in the conventional case. Then, the communication unit 130
Connects the reservoir 120 and the space 110 at both ends of the reservoir 120.
0 goes around into the reservoir 120 through the communicating portion 130.

The apparatus section 40 is placed in the molding die 100 and the resin 50 is filled therein. Thereby, the resin 50
Is a device sealing portion 51 formed in the space 110 for sealing the device portion 40, a pool resin portion 52 formed in the pool portion 120, and a guide frame cutting portion (broken line S in FIGS. 1 and 3). , And a connecting resin portion 53 that connects the device sealing portion 51 and the accumulated resin portion 52 to each other.

At the time of cutting the guide frame 33, in order to remove the accumulated resin portion 52 which is an unnecessary resin,
The connection resin portion 53 is cut along the broken line S in FIGS. 1 and 3. Here, the resin 5
Since a large amount of 0 is accumulated, the connecting resin portion 53 is sufficiently thick so that it can be appropriately divided, and thus it is considered that burrs of the resin 50 are less likely to occur on the end portion 21 of the heat sink 20 as in the conventional case. .

However, after further study,
The following problems occurred. FIG. 4 shows C- in FIG.
It is a figure which shows the cross section when the connection resin part 53 is cut | disconnected along the dashed-dotted line C (cutting line), and only the said cross section is hatched.

As shown in FIG. 4, cutting is performed in the direction of the white arrow, and the cut surface within the range indicated by reference numeral 53 is the connecting resin portion 5.
The cut surface is 3. Here, both ends of the connecting resin portion 53 formed by the communicating portion 130 of the molding die 100 (see FIG. 3).
Portion shown as connection resin portion 53 in FIG.
a is a thick portion having a larger thickness in the cutting direction than the intermediate portion 53b between the both end portions 53a, and the width t in the direction orthogonal to the cutting direction (see also FIG. 2) is It is relatively thin.

As described above, in the molding die 100, the passage area of the communication portion 130 (see FIGS. 2 and 3) is secured so that the resin 50 from the space portion 110 can flow into the accumulation portion 120. This is because. therefore,
Both end portions 53a of the connecting resin portion 53, which are formed by the communicating portion 130, are elongated in the cutting direction as compared with the intermediate portion 53b.

If the width t shown in FIGS. 2 and 4 is small at both ends of the connecting resin portion 53, the connecting resin portion 53 is not bent at the both end portions 53a when the connecting resin portion 53 is cut. It is hard to be cut by. Further, if the width t is too large, the resin 50 (device sealing portion 51) on the device portion 40 side is chipped due to a large stress at the time of cutting, and cracks or peeling are generated from the chip to cause intrusion of moisture. And other problems occur.

Therefore, in view of the above problems, the present invention is an electronic device for encapsulating a device portion provided with a heat sink on which a heat generating element is mounted and a lead frame so as to be wrapped with resin in a state where an end portion of the heat sink is exposed. In the above manufacturing method, it is an object of the present invention to appropriately cut unnecessary resin parts at the same time when cutting the lead frame.

[0019]

In order to achieve the above object, in the invention described in claim 1, the heat sink (20) on which the heating element (10) is mounted and the lead frame (3).
0) is disposed in the molding die (100) and the molding die is filled with the resin (50), so that the end of the heat sink is exposed from the resin. In a method of manufacturing an electronic device in which a resin is wrapped and sealed, first, as a molding die, a space portion (110) filled with resin for sealing a device portion therein,
A sump (120) positioned adjacent to the outside of the end (21) of the heat sink exposed from the resin and accumulating the resin.
And a communication part (130) that connects the space part and the reservoir part.

Next, the device part (4) is placed in the molding die (100).
0) is placed, a step of filling the resin (50) and hardening the resin is performed, and then the guide frame (33) of the lead frame (30) is cut and formed by the communicating portion (130) of the molding die. And a step of cutting the connected resin portion (53a) that has been cut.
The width (t) of the communicating portion in the direction orthogonal to the cutting direction of the connecting resin portion is characterized by being 0.05 mm or more and 0.15 mm or less.

According to the manufacturing method of the present invention, the molding die (10) in the direction orthogonal to the cutting direction of the connecting resin portion (53a) is formed.
By setting the width (t) of the communication part (130) of 0) to be 0.05 mm or more and 0.15 mm or less, a relatively thick part (thick part) formed by the communication part of the molding die in the connecting resin part. The width of () is also 0.05 mm or more and 0.15 mm or less.

When the width of the thick-walled portion of the connecting resin portion is within the above range, it is possible to prevent the thick-walled portion from being bent and hard to be cut or the resin from being chipped when the lead frame is cut. . Therefore, according to the present invention, unnecessary resin portions can be appropriately cut at the same time when the lead frame is cut.

Here, as in the invention described in claim 2,
An epoxy resin can be used as the resin (50).

The reference numerals in parentheses of the above-mentioned means are examples showing the correspondence with the concrete means described in the embodiments described later.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. The molding die used in the electronic device and the manufacturing method thereof according to the present embodiment is based on the configuration shown in FIGS. Therefore, although there may be a case where it overlaps with the above based on FIGS. 1 to 4, the characteristics of this embodiment will be mainly described here.

As shown in FIGS. 1 and 2, in the electronic device, a device section 40 includes a heat sink 20 made of Cu or the like on which a heating element 10 such as a power IC is mounted, a lead frame 30 made of Cu or the like, The heating element 10 and the lead portion (inner lead) 34 of the lead frame 30 are connected to each other by a wire 60 such as Al or Au.

The device section 40 includes a heat sink 20.
In the state where the end portion 21 of the chip mounting surface and the back surface of the mounting surface are exposed, they are sealed so as to be wrapped with a resin (mold resin) 50. Here, as the resin 50,
A resin curable by heat or the like, preferably an epoxy resin, can be used.

Further, by exposing the end portion 21 of the heat sink 20, as in the case of FIG.
The radiating fins of the U substrate and a mounting case (not shown) can be screwed and fixed. In FIG. 2, the end portion 21 of the heat sink 20 is provided with a round hole 22 into which a fixing screw is inserted.

In this electronic device, the heat generating element 10 is mounted on the heat sink 20 by using a conductive adhesive or solder, and the heat generating element 10 and the lead frame 30 are connected by the wire 60 by wire bonding or the like. After forming the part 40, the device part 40 is moved to the molding die 1 as shown in FIG.
It is placed in 00.

FIG. 5 shows an example of a more detailed plane structure of the lead frame 30 used for resin molding, and FIG. 5 shows the multiple states of the lead frame 30 of this example. The lead frame 30 used for is not limited to the examples shown in FIGS. 5 and 6. In FIGS. 5 and 6, the alternate long and short dash line area is an area sealed (molded) with the resin 50.

The lead frame 30 shown in FIG. 5 is made of a Cu plate, and has a mounting portion 31 having a mounting hole 32 for caulking and fixing the heat sink 20, a guide frame 33 to be cut and removed at the end, and the heating element 10. And a lead portion 34 which is wire-bonded to and connected to. In addition, in place of the lead frame 30,
Holes and recesses are formed to engage with the resin 50 and enhance the adhesion.

Further, in FIG. 5, finally, the lead frame 30 is sealed with the resin 50 as shown by the alternate long and short dash line, and the guide frame 33 and the tie bar 36 are divided along the outer shape of the resin 50. . Here, the lead portion 34 of the lead frame 30 is sealed with the resin 50, and is divided into an inner lead inside the resin 50 and an outer lead outside the resin 50.

Further, in the portion of the guide frame 33 located on the lower side of FIG. 5, a concave portion 35 which is recessed away from the heat sink 20 is formed at a position adjacent to and facing the end portion 21 of the heat sink 20. . A reservoir 120 of the molding die 100 is formed at a position corresponding to the recess 35.

Further, as shown in FIG. 6, the lead frame 30 of the present example has a reel shape, and a plurality of electronic devices can be manufactured at one time. Here, the lead frame 30
Although the heat sink 20 and the heat sink 20 may be separately arranged in the molding die 100, the lead frame 3 shown in FIGS.
In No. 0, the lead frame 30 and the heat sink 20 can be integrated and then arranged by caulking.

Specifically, the projection (not shown) formed on the heat sink 20 is attached to the mounting hole 32 of the lead frame 30.
Then, the heat sink 20 and the lead frame 30 are fixed to each other by crimping and crushing the tip of the protrusion.

The molding die 100 of this embodiment can be divided into, for example, an upper die and a lower die with the lead frame 30 interposed therebetween. As shown in FIGS. 1 to 3, inside the molding die 100, the space portion 110 filled with the resin 50 for sealing the device portion 40 and the outside of the end portion 21 of the heat sink 20 are adjacent to each other. It has a reservoir part 120 as a space in which the resin 50 is located and a communication part 130 that communicates the space part 110 with the reservoir part 120.

In this way, the device section 40 is attached to the molding die 10.
After being placed in 0, the resin 50 in a fluid state is injected into the molding die 100. Then, in the molding die 100, the resin 50 is filled from the space portion 110 to the reservoir portion 120 via the communication portion 130. Thereafter, the resin 50 is cured, so that the device section 40 is resin-sealed in the form shown in FIGS.

In the resin-sealed state shown in FIGS. 1 to 3,
The formed resin 50 serves as a device sealing portion 51 formed by the space 110, a pool resin portion 52 formed by the reservoir 120, and a boundary portion between the device sealing portion 51 and the pool resin portion 52. It is composed of a connecting resin portion 53 that connects both portions 51 and 52.

After the resin is thus sealed, the guide frame 33 and the tie bar 36 of the lead frame 30 are cut and removed using a cutting tool or the like. Simultaneously with this cutting, a cutting line S (see FIG. 2) indicated by a broken line in FIGS.
(Corresponding to C-C dashed line inside)
3 is also cut. Then, the accumulated resin portion 52 is removed. Thus, the electronic device (resin-sealed electronic device) of this embodiment is completed.

Here, also in this embodiment, the cut surface of the connecting resin portion 53 is as shown in FIG. That is, the communication portion 130 of the molding die 100 of the connection resin portion 53.
Both end portions 53a formed by are thicker portions in the cutting direction than the intermediate portion 53b, and
The width t in the direction orthogonal to the cutting direction is relatively thin.

In this embodiment, the molding die 100 is devised so that the width t of both end portions 53a of the connecting resin portion 53, which is the thick portion, is 0.05 mm or more and 0.15 mm or less.

The shape of both end portions 53a of the connecting resin portion 53 is defined by the shape of the communicating portion 130 of the molding die 100, and the width t of the both end portions 53a of the connecting resin portion 53 is t.
Is also the width of the communication portion 130. That is, in the present embodiment, as the molding die 100, the connecting resin portion 53 (both end portions 53
The width t of the communicating portion 130 in the direction orthogonal to the cutting direction of a).
However, it is characterized by using a material having a thickness of 0.05 mm or more and 0.15 mm or less.

According to this, the communicating portion 13 of the molding die 100.
By setting the width t of 0 to be 0.05 mm or more and 0.15 mm or less, a relatively thick portion (thick wall portion) formed by the communicating portion 130 of the molding die 100, that is, both end portions 53a of the connecting resin portion 53. Width t (see Fig. 4) is also 0.05m
It becomes m or more and 0.15 mm or less.

Both end portions 53 of the connecting resin portion 53 which is a thick portion
When the width t of a is in this range, it is possible to prevent the both end portions 53a from being bent and difficult to be cut, and the resin 50 from being chipped when the lead frame 30 is cut. Thus, according to the present embodiment, the lead frame 3
When cutting 0, unnecessary resin portions can be cut appropriately at the same time.

Setting the width t of the communicating portion 130 of the molding die 100 within the above range is based on the result of the study by the present inventor as described below. Connection resin portion 53 shown in FIG.
In the cut surface of, for example, the length (width) of the intermediate portion 53b
Can be about 7 mm, the thickness can be about 0.2 mm to 0.3 mm, and the thickness of both ends 53a having the width t can be about 0.5 mm.

Here, the communicating portion 13 of the molding die 100.
By changing the width t of 0, both end portions 53 of the connecting resin portion 53
The width t of a was changed and the cutting state of the connection resin part 53 was investigated. The result is shown in FIG. 7. In FIG. 7, the width t (unit: m
The horizontal axis represents m) and the vertical axis represents the failure occurrence rate (%) as the cutting status.

As for the defect occurrence rate, when a large number of samples having a constant width t are cut, burrs are left without being cut well and the resin 50 on the device section 40 side is cut.
The number of occurrences of defects such as chipping in the (device sealing portion 51) is shown in percentage.

Here, the chipping of the device sealing portion 51 was regarded as defective when the size thereof was 0.6 mm or more from the cut portion. If the chipping is 0.6 mm or more, there is a problem in appearance and it is difficult to secure reliability, and if it is smaller than 0.6 mm, there is no problem in practical use.

As shown in FIG. 7, the width t is 0.05 m.
If it is smaller than m, defects will occur, and as it becomes smaller, defects will be more likely to occur. This has a width t of 0.05 mm
If it is smaller than the above, the rigidity of both ends (thick parts) 53a of the connecting resin portion 53 is lost when the lead frame 30 is cut, and the lead frame 30 bends and is not cut.
This is because it remains as burr.

On the other hand, as shown in FIG. 7, the width t is 0.
If it is larger than 15 mm, a defect occurs, and if it is larger, the defect is more likely to occur. This has a width t of 0.1
If it is larger than 5 mm, the rigidity of both end portions 53a of the connecting resin portion 53 is too strong, and the device sealing portion 51 is uprooted at the time of cutting, so that a large chip is likely to occur.

Therefore, from the results shown in FIG. 7, it is derived that the width t of both end portions 53a of the connecting resin portion 53, that is, the width t of the communicating portion 130 of the molding die 100 is set to 0.05 mm or more and 0.15 mm or less. .

The present invention is not limited to the electronic device of the above-mentioned embodiment, and the device portion including the heat sink on which the heating element is mounted and the lead frame is made of resin with the end portion of the heat sink exposed. Needless to say, the present invention can be applied to any resin-sealed type electronic device that is sealed by enclosing it.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an electronic device and a molding die according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the electronic device shown in FIG.

3 is a schematic cross-sectional view taken along the line BB in FIG.

FIG. 4 is a view showing a cross section when the connecting resin portion is cut along the line C-C in FIG.

FIG. 5 is a specific plan view of a lead frame used in the manufacturing method of the above embodiment.

FIG. 6 is a plan view showing a multiple state of the lead frame shown in FIG.

FIG. 7 is a diagram showing a relationship between a width t of both ends of the connecting resin portion and a cutting state of the connecting resin portion.

FIG. 8 is a schematic cross-sectional view of a general electronic device.

FIG. 9 is a diagram showing a method for manufacturing a general electronic device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Heating element, 20 ... Heat sink, 21 ... End of heat sink, 30 ... Lead frame, 33 ... Guide frame, 40 ... Device section, 50 ... Resin, 53 ... Connection resin section,
100 ... Mold, 110 ... Space part, 120 ... Reservoir part,
130 ... Communication part, t ... Width of the communication part in the direction orthogonal to the cutting direction of the connecting resin part.

Claims (2)

[Claims] 1. A device part (40) including a heat sink (20) on which a heating element (10) is mounted and a lead frame (30) is arranged in a molding die (100), and a resin is provided in the molding die. In the method of manufacturing an electronic device, which is filled with (50) so as to enclose the device part with the resin in a state where the end part of the heat sink is exposed from the resin, as the molding die, A space (110) that is filled with the resin to seal the device part and a reservoir that is positioned adjacent to the outside of the end (21) of the heat sink exposed from the resin and in which the resin accumulates. Department (1
20) and a communication part (130) that communicates the space part and the reservoir part, prepare the device part in the mold, fill the resin, and cure the resin. A step of cutting the guide frame (33) of the lead frame, and a step of cutting the connecting resin portion (53a) formed by the communicating portion of the molding die, the molding die comprising: A method of manufacturing an electronic device, wherein a width (t) of the communication portion in a direction orthogonal to a cutting direction of the connection resin portion is 0.05 mm or more and 0.15 mm or less. 2. The method of manufacturing an electronic device according to claim 1, wherein an epoxy resin is used as the resin (50).