JPH0444425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a resin-sealed semiconductor device.

(Conventional technology and its problems) In a resin-molded semiconductor device, a semiconductor element is mounted on a lead frame formed into a predetermined circuit pattern, the semiconductor element and internal leads are wire-bonded, and then the semiconductor element is molded with resin. It is then sealed and formed.

Some lead frames used in this resin-sealed semiconductor device are provided with a dam bar that connects the external leads so that the resin is not pushed out into the gap between the external leads during resin sealing.

As shown in FIG. 8, the dam bar 10 is removed by being cut with a knife 12 after being sealed with resin. 0.3mm
They are located approximately 0.4mm apart. However, if the dam bar 10 is provided apart from the resin main body 14 in this way, the resin will naturally be extruded into the gap as a resin burr 16, and the cutter 14 will be forced out during cutting.
2 will also cut a part of this resin burr 16 at the same time, but since ceramic, glass, etc. are mixed in the resin, there is a problem that it will damage the cutter and significantly shorten its life.

Further, after cutting the dam bar 10, a finishing step is required to remove the resin burr 16, and its original function as a dam bar is also diminished.

Furthermore, in recent years, the number of external leads has increased more and more, and the gaps between the leads have become smaller, making it difficult to cut with a knife.Therefore, there is a strong demand for a method for removing dam bars without using a knife.

The present invention was made in response to the above-mentioned needs, and its purpose is to effectively prevent the occurrence of resin burrs and to easily remove the dam bar without damaging the cutter or without using a cutter. An object of the present invention is to provide a method for manufacturing a resin-sealed semiconductor device.

(Means for Solving the Problems) In the present invention for the above-mentioned purpose, a semiconductor element is mounted on a lead frame having a dam bar for connecting external leads, is assembled into a mold, and a resin is injected into the mold. In the method for manufacturing a resin-sealed semiconductor device, in which the dam bar prevents molten resin from flowing between external leads when the element is resin-sealed, and the dam bar is removed after molding, the lead frame includes a dam bar inside. The dam bar is provided so that its edge is in contact with the outer line of the resin-sealed area, and at least the resin-sealed area side of the planned side line position of the external lead on the dam bar is shifted in one direction in the thickness direction with respect to the external lead. The lead frame formed in the semi-sheared part is used to perform the steps up to the resin sealing process, and then when the lead frame is assembled into the mold and the mold is clamped, it is pressed with the barting surface of the mold. The dam bar is pushed back to a position that matches the external lead surface, and then resin is injected into the mold.

(Function) In a semi-sheared state where the dam bar is simply shifted in one direction in the thickness direction of the external lead, a part of the metal structure is connected, and therefore this is a step before the resin sealing step. The dam bar will not fall off during the semiconductor element bonding process, wire bonding process, etc.

When clamping the mold in the resin sealing process, the dam bar is pressed back with the parting surface of the mold at the same time.
In addition to functioning as a dam bar, the semi-sheared part in this pushed back state has the metal structure cut off, making it extremely easy to remove.
The dam bar can be easily removed in the subsequent removal process.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail together with their functions based on the accompanying drawings.

FIG. 1 is a schematic diagram showing an example of a lead frame 20 used in the method of the present invention. 22 is an external lead thereof, 24 is an internal lead following the external lead 22, and 26 is a dam bar that connects the plurality of external leads 22 and connects to the rail portion 28. A stage 30 is an element mounting section, and is connected to the rail section 28 by a stage support bar 32.

As shown in FIG. 2, the lead frame 20 is resin-sealed after a semiconductor element 34 is assembled on a stage 30, wire bonding is performed, and a protective film 36 is formed.

In the present invention, the position where the dam bar 26 is provided is such that its inner edge 38 is aligned with the outer line of the resin body 40.
It is set to match 2. The resin-sealed area is indicated by a chain line in FIG.

Further, in the present invention, a semi-sheared portion is provided on the dam bar 26 at the position of the external lead planned side line 44 (FIG. 3).

The structure of the half-shear section is shown in FIG. FIG. 4a is a sectional view taken along the line XX in FIG. 3, and FIG. 4b is a sectional view taken along the line YY in FIG. In this embodiment, the dam bar 26 is pressed against the external lead 22 by a male mold 46 and a female mold 48 so that it is lifted from the surface of the external lead 22 by approximately half the thickness in the thickness direction, and the side line 44 where the external lead is to be formed is pressed. A half-shear section is formed on the top. In this half-sheared part, the dam bar 26 and the external lead 22 are in contact with each other in a part and have the necessary strength, but because the metal structure is misaligned along the half-sheared surface, they are not easily affected by external force from the thickness direction. This makes it easier for them to leave.

Note that the degree of this semi-shearing process needs to be adjusted so that the dam bar 26 does not fall off when handling the lead frame after the process.

FIG. 5 is an explanatory diagram showing a case where this state is resin-sealed using the lead frame 20. When the upper mold 50 and the lower mold 52 are clamped, the dam bar is pressed by the parting surface and lifted up. 26
is again pushed back to the surface of the external lead 22. Therefore, the resin does not protrude and functions as a dam bar. The dam bar 26 that has been pushed back in the opposite direction to the shearing direction is in a state where it is easier to detach, and in the subsequent process, it can be removed by hand, with a thruster (not shown), or by sandblasting, etc. without using a knife. It is easily detached by external force.

Further, when the external leads 22 are bent and formed after resin sealing, it is also possible to cause the dam bars 26 to fall off when the external leads 22 are bent.

Figure 6 shows the side line 4 where the above shearing process is planned to be led externally.
This is an example of applying it to a part of 4 (resin main body side).
This corresponds to the XX sectional view in the figure. In this case as well, the dam bar 26 is raised and pushed back during mold clamping during resin sealing, as described above. In this embodiment, the strength of the dam bar 26 can be maintained constant.

FIG. 7 shows another embodiment of the half-shear section, and the figure a
In this example, the dam bar 26 is tilted toward the resin body 40 side with respect to the surface of the external lead 22, and the whole or a part thereof is semi-sheared. In Figure b, the resin main body 40 side is processed so that it is a completely sheared surface, the middle part is a semi-sheared surface, and the base part is not sheared. In the case of this embodiment, the connection strength differs along the fracture surface, and there is an effect that it is easy to set the necessary connection strength for the dam bar 26 as a whole.

In the embodiments shown in FIGS. 6 and 7b above, a knife may be required to remove the dam bar 26, but the cutting point should be a non-sheared part on the side far from the resin body 40. Since it is only necessary to cut, there is no risk of the blade biting the resin body 40 during cutting.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. That's true.

(Effects of the Invention) As described above, according to the method for manufacturing a resin-sealed semiconductor device according to the present invention, the semiconductor element bonding step,
The steps before the resin sealing process, such as the wire bonding process, are carried out in a semi-sheared state in which the dam bar is simply shifted in one direction in the thickness direction of the external lead, and a part of the metal structure is connected. Therefore, the dam bar will not fall off during the process. When the lead frame is assembled into the mold, the parting surface of the mold is pressed to simultaneously push the dam bar back to the position that matches the external lead, so a separate push-back process is unnecessary and the dam bar can function as it is. In addition, by pushing back the half-sheared portion, the dam bar is in a state where it is extremely easy to remove from the external lead, and the dam bar can be easily removed later.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a lead frame used in the method of the present invention, FIG. 2 is an explanatory cross-sectional view when resin-sealed, and FIG. 3 is an explanatory view showing planned side lines of external leads. FIG. 4 is a sectional view showing the configuration of a half-sheared portion of the dam bar, and FIG. 5 is an explanatory view showing a state in which an element is assembled into a lead frame and placed in a resin mold. Fig. 6 is a cross-sectional view of a dam bar partially sheared, Fig. 7 is a cross-sectional view of a dam bar tilted and semi-sheared, and Fig. 8 is a conventional manufacturing process for a resin-encapsulated semiconductor device. It is an explanatory view showing a state where a dam bar is cut in the process. 10... Dam bar, 12... Cutler, 14... Resin body, 16... Resin burr, 20... Lead frame, 22... External lead, 24... Internal lead, 26... Dam bar, 28... Rail section , 30
... Stage, 34 ... Semiconductor element, 36 ... Protective coating, 38 ... Inner edge, 40 ... Resin body, 4
2...External line, 44...External lead planned lateral line, 4
6...Male type, 48...Female type, 50...Upper type, 52
...lower mold.

Claims (1)

[Claims] 1. A semiconductor element is mounted on a lead frame having a dam bar that connects external leads and is assembled into a mold, and when resin is injected into the mold and the semiconductor element is sealed with the resin, the semiconductor element is melted by the dam bar. In a method for manufacturing a resin-sealed semiconductor device in which a dam bar is dammed to prevent resin from flowing out between external leads and a dam bar is removed after molding, the lead frame has a dam bar with an inner edge aligned with an outer line of a resin-sealed area. Using a lead frame, the dam bar is provided so as to be in contact with the external lead, and at least the resin-sealed area side of the planned side line position of the external lead on the dam bar is formed into a semi-sheared part in which the dam bar is shifted in one direction in the thickness direction with respect to the external lead. The process up to the step before the resin sealing process is performed, and then, when the lead frame is assembled into a mold and the mold is clamped, the dam bar is pushed back to a position where it matches the external lead surface by pressing with the parting surface of the mold. A method for manufacturing a resin-sealed semiconductor device, which comprises subsequently injecting a resin into the mold.