JPS60121747A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the corners of a mold part from tipping at the time of cutting tab leads by a method wherein a corner of the mold part intersecting the tab leads is formed in cutout shape. CONSTITUTION:A tab 12 where a semiconductor element is mounted is formed at the center of the frame section of a lead frame. This tab 12 is supported at least at its two corners by the inner ends of the tab leads 13 respectively connected to the frame section 10 of the lead frame. The semiconductor element 11 is fixed to the tab 2 thus formed and molded with resin, and the element 11 is covered with the mold part 17 made of resin. At this time, the corner of the mold part 17 intersecting the leads 13 is molded to the chamfered state having a plane 18 so cut as to rectangularly intersect the leads. This manner enables the corner of the mold part 17 from breaking at the time of cutting the leads 13 at the root of the mold part 17.

Description

[Detailed description of the invention] The present invention relates to a resin molded semiconductor device.

Metal lead frames are used to assemble resin molded semiconductor devices. This lead frame is formed by punching out a thin metal plate with a press or by etching, and its shape is as shown in FIG.
A tab lead 3 that supports a rectangular tab 2 with its inner end to which the tab 2 is attached, a plurality of boards 4 whose inner ends face the periphery of the tab 2, and a rectangular frame that supports these leads 4 and the outer ends of the tab lead 3. a frame portion 5 and a frame portion 5. It consists of a dam piece 6 that connects each lead 4 and tab lead 3 and prevents melted resin from flowing out during resin molding. In addition, the frame portion 5
Guide holes 7 are provided at regular intervals along both side edges of the lead frame, and the guide holes 7 are used as positioning holes and hook transfer holes 2 during assembly and transportation using the lead frame.

To assemble a semiconductor device using such a lead frame, first attach the semiconductor element 1 onto the tab 2, and then connect each electrode of the semiconductor element 1 to the inner end of the corresponding lead 4 with a wire 8. Thereafter, the inner regions of the dam pieces 6 arranged along the rectangular frame are molded with resin, and the semiconductor element 1 etc. are covered with the molded part 9. Then, the dam piece 6 and the frame portion 5 are cut and removed to obtain a flat lead semiconductor device.

Furthermore, in order to obtain an in-line type semiconductor device, the leads 4 protruding from the mold part 9 are bent in the middle.

By the way, since the tab has a structure in which both sides of the tab are supported by thin tab leads, its strength is weak.

In particular, as the number of leads increases recently, and in order to maintain miniaturization, the width of the leads (tab leads) must also become narrower (・0.
．． 30 width), the material used to make the lead frame has to be thinner than before due to problems in the punching process (for example, 0.30 width).
．． 15 parrots). As a result, the tabs, like the leads, can easily tilt or lift even with a small external force, causing trouble in assembly. For example, when attaching a semiconductor element, the tab swings, resulting in incomplete bonding, and during wire bonding, incomplete bonding and wire breakage occur. In addition, during resin molding, the tab may tilt and move due to the flowing resin, causing the wire to break, or the tab may roll, creating a vortex, which may cause air bubbles to remain inside the mold or on its surface, reducing moisture resistance or creating dents. This results in a poor appearance.

A resin molded semiconductor device with leads taken out from all sides is disclosed in Japanese Patent Application Laid-open No. 80969/1983.

Therefore, an object of the present invention is to provide a semiconductor device with excellent bonding reliability and moisture resistance for wires and semiconductor elements by providing a lead frame with excellent rigidity in which the tabs do not easily move during assembly. . Another object of the present invention is to provide a lead frame that can improve assembly yield.

In order to achieve such an object, the present invention assembles a semiconductor device using a lead frame in which at least two corners of a rectangular tab on which a semiconductor element is attached are supported by tab leads. Detailed explanation of.

FIG. 2 is a plan view showing one embodiment of a lead frame used in the present invention, FIG. 3 is a plan view of a semiconductor device assembled using the lead frame shown in FIG. 2, and FIG. 4(a)
, (b) is a plan view and a partially enlarged view showing the state during one assembly process.

First, the shape of the lead frame will be explained. This lead frame is made from a metal plate with a thickness of 0.15 mm by punching or etching. Although there are parts with different widths, the frame part 10 forms a rectangular frame as a whole and has a rectangular tab 12 in the center of which the semiconductor element (pellet) H1 is attached. This tab 12 is supported at its four corners by the inner ends of thin tab leads 13 whose outer ends are respectively connected to the partitions of the frame portion 1o. Further, a plurality of leads 14 extend toward this tab 12 from four directions, and their tips (inner ends) are connected to the tab 120.
It faces near the periphery. In addition, leads 1 extending in four directions
The rear ends of 4 are connected to the inside of the frame 10, respectively.

Further, a dam piece 15 extending between each lead and between the lead and the frame portion 10 is arranged to surround the tab 12 in order to prevent melted resin from flowing out during resin molding. Further, a guide hole 16 is bored in the frame portion 10 as in the conventional case.

When assembling a semiconductor device using such a lead frame, as shown in FIG. (as shown in Figure 3), then connect the dam piece 1 as shown in Figure 4 (a>).
The inside of 5 is molded with resin, and the semiconductor element 11 and the like are covered with a molded part 17 made of resin. At this time, Fig. 4 Q
)), the corners (corners) of the mold part 170 that intersect with the tab lead 13 are perpendicular to the tab lead 13.
V-Mold into a chamfered configuration with a notched surface 18. This is a result of consideration taken to prevent the corners of the molded portion from being chipped when cutting the tab lead at the base of the molded portion. Next, the tab lead 13 is cut at the base of the mold part 17, and the unnecessary dam piece 15 and frame part 1o are cut and removed to obtain a full-circuit semiconductor device. In addition, if necessary, a long guide 14 may be provided that protrudes from the mold portion 17.
An in-line type semiconductor device is made by bending it from the middle.

In this embodiment, the tab 12 is supported at its four corners by the tab leads 13, so it is difficult to move and has excellent rigidity. Therefore, it does not tilt or lift off the work table during each assembly operation. Therefore, reliable connection (bonding) can be achieved during pellet bonding or wire bonding. Further, during resin molding, the tab is not tilted by the inflowing resin, so no vortices are generated due to the shadow of the flow, and no air bubbles are generated. Furthermore, since the tab does not tilt, strong force is not applied to the wire and the wire does not break.

Note that the present invention is not limited to the above embodiments. for example,
The tab lead may be provided with a 7-shaped groove along the periphery of the mold part at a position that is the boundary with the mold part, so that the tab lead can be easily separated from the 7-shaped groove when cutting the tab lead.

Further, one or more of the plurality of tab leads may be used as leads.

In addition, in the case of a structure in which the corners of the mold part are not chamfered, as shown in FIGS.
Alternatively, the middle of the separation lead 19 may intersect with the outer circumferential surface of the mold part so that the corner of the mold part is not damaged when the tab lead is cut. The separation lead 19 is cut along the dashed line shown in FIG. 6(a). In addition, a V is also placed at this cutting point to make it easier to cut, as shown in Figure 6(a).
A groove 20 may also be provided.

In addition, as shown in FIG. 7(a), the space formed by the two Y-shaped separation leads 19 and the frame 10 (dam piece 15) is widened toward the frame so that it is thicker. If the gate 21 is for resin injection during resin molding, the seventh
As shown in Figure 0]), there is a step on the runner 22, and when the mold part and the launch are separated, stress concentration acts on this step, causing separation at this step (separation is shown in Figure 7). This is the chain line part. ).

Therefore, the shape of the runner separation part in the molded product is constant, and the problem of irregular separation parts can be prevented.

Furthermore, even though this lead frame has a structure in which the tab portion is lowered, the strength (steel column) is high.

As described above, according to the present invention, since the tab has high strength, it does not easily move during assembly. For this reason,
Bonding such as wire bonding and pellet bonding can be performed reliably and with high reliability. Furthermore, since no air bubbles are generated inside or on the surface of the mold during resin molding, it has excellent moisture resistance and does not impair its appearance. Furthermore, since the tab does not tilt or move during resin molding, no large force is applied to the wire, so the wire does not break.

For these reasons, it is possible to assemble a semiconductor device with excellent characteristics, and the yield in assembly is also improved. In addition, the thickness of the lead frame is thinner than before, and the tab does not move during resin molding, so the desired sealing can be achieved even if the mold is thin, resulting in many effects such as making the product more compact. .

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a conventional lead frame, FIG. 2 is a plan view showing an embodiment of the lead frame used in the present invention, and FIG. 3 is a plan view showing an embodiment of the semiconductor device of the present invention. 4(a) and 4(b) are a plan view and a partially enlarged view of a semi-finished product in one work step in manufacturing the semiconductor device of the present invention, and FIG. 5 is another implementation of the lead frame used in the present invention. FIGS. 6(a) and 6(b) are plan views according to the example, and FIG. 7(a) is an explanatory view of the molded state and a partially enlarged perspective view of the tab lead. (b) is an enlarged plan view of the resin injection gate portion of the lead frame and an explanatory diagram showing the state during molding. 1...Semiconductor element, 2...Tab, 3...Tab lead, 4.!・Lead, 5 Middle frame part, 6... Dam piece, 7 River guide hole, 8... Wire, 9... Mold part, 1o
...Frame portion, 11...Semiconductor element, 12...Tab,
13...Tab lead, 14...Lead, 15...
Dam piece, 16... Guide hole, 17... Mold part,
18... Notched surface, 19... Separation lead, 20
...7-shaped groove, 21...resin injection gate, 22.
··lunch. Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A rectangular tab with a semiconductor element fixed to its main surface, a mold part made of resin that covers the tab and the semiconductor element, and a mold part extending from the periphery of the tab to reach the peripheral surface of the mold part. A tab lead, a plurality of leads whose outer ends protrude from the surface of the mold part and face near the periphery of the tab inside the mold part, and a plurality of leads located inside the mold part that connect the inner ends of the leads and the electrodes of the semiconductor element. 1. A semiconductor device comprising a wire, wherein the tab lead extends from at least two corners toward a curved surface of a mold part, and at least one corner of the mold part has a cutout shape. 2. The cutout portion described in claim 1 is
A semiconductor device characterized in that the surface is perpendicular to the tab lead. 3. In the semiconductor device according to claim 1,
A semiconductor device characterized in that a mold part has a shape in which four corners are cut out.