JPS5895851A - Lead frame - Google Patents

Abstract

PURPOSE:To obtain the structure of the lead frame which effectively stops the outflow of resin flowing out from a section between external lead metallic pieces and can remove the metallic section of the lead frame functioning as the stop of the flow without giving a mechanical shock just after the frame is molded with resin when the frame is sealed with resin. CONSTITUTION:A metallic plate 7 worked through punching working as shown in the figure (a) is previously formed in the shape only of an internal lead body up to a section in the vicinity of a resin molding line, and the metallic plate is formed by means of a punching die without being separated from an outer frame 10 left around external lead bodies 8 or a connecting section 11 connecting the frame to sections to which other molding sections are shaped so that metallic sections 9 to be punched among external leads serve as the stop of the flow of resin when the frame is sealed with resin when the external lead bodies 8 are formed as shown in the figure (b). The noses of the metallic sections 9 of the stop of the flow of the resin-that is, end surfaces 13 contacting with the resin molding line 12 shown in a dotted line-are worked so as to be positioned along the molding line or be arranged at positions slightly displaced in the outward direction from the resin mold section.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead frame used as an external electrode of a semiconductor device such as a semiconductor integrated circuit device.

In particular, it has a metal part that can effectively prevent the resin from flowing out between the outer lead metal pieces of the part of the lead body that protrudes from the resin mold line during resin sealing, and this flow stopper. The present invention provides a lead frame structure that allows the sharp metal portion of the lead frame to be removed from a semiconductor device immediately after resin molding without applying a mechanical shock.

FIG. 1 shows the flow of resin from between lead frames protruding from a conventional resin part. Figure 1 (a) shows an external lead body 1 that is at an appropriate distance from the resin mold line and does not reach the connection part with the wiring board to be mounted during mounting, and the space between these external lead bodies. This lead frame has a structure in which a metal bar 2 is provided so as to connect the two, and the metal bar 2 stops the resin from flowing out near the mold resin end face (so-called resin mold line) 3. And when using this lead frame.

After molding the necessary parts with resin, the bar 2 is cut by a method such as press working.

The semiconductor device having the structure as shown in FIG. 1(a) is
In the resin sealing process, the above-mentioned part is placed relatively close to the resin part 4 in order to prevent resin contamination from reaching the lead body part for mounting it on a printed circuit board as a desired electronic device component, for example. Metal bar 2 is placed.

When cutting the metal bar 2 from the external lead body 1 after resin sealing, if a mechanical method such as punching is used, large external forces such as tensile force or impact force may be applied to the semiconductor device already molded with resin. This easily damages the adhesion between the resin and the internal leads 6 located inside the resin, and significantly reduces the moisture and water resistance to 1% reliability. Further, methods for cutting the metal bar 2 include laser light, discharge cutting, etc., but these methods are generally inefficient.

Next, another example of resin outflow prevention will be explained.

In Fig. 1 (B), between an external lead body 1 and an adjacent external lead body, a convex portion is formed on the external lead 1 from the surface contacting the lead frame of the mold die with an extremely small interval between the leads. A method is shown in which a portion 6 is provided and used as a dam block to prevent resin from flowing out during resin molding. According to this method, it is possible to completely prevent thin resin flakes and flash-like resin leakage from the gap between the convex portion 6 and the external lead body 1. is leaked.

Mechanically, they are in close contact with the printed wiring board for mounting.
Adversely affects electrical coupling. Further, it requires a great deal of effort to remove the thin resin particles and the like that have flowed out and adhered to the resin in a subsequent process.

The present invention proposes a lead frame structure that eliminates such disadvantages.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 2 shows an example of manufacturing a lead frame according to an embodiment of the present invention.
This is shown in an exploded process diagram.

That is, the metal plate 7 processed by the throat punching process shown in FIG. 2 (a) is made into a shape in advance that only has an internal lead body up to the vicinity of the resin mold dryer, and then this is formed into the shape shown in FIG. 2 (b). As shown in FIG. 2, when forming the external lead body 8, an outer frame 10 is left around the external lead body 80 so that the metal portion 9 to be punched out between the external leads serves as a stopper for resin flow during resin sealing. Or, without separating from the connecting part 11 that connects with the part forming another mold part, and each external lead body 8 is connected to the external lead body 8 over a sufficient distance to obtain the necessary length as an external lead. The resin flow stopper portion 9 separated in a cut state is formed by a punching die.

In this punching process, when the resin fastening metal part 9 as shown in FIG.
- The resin flow stopper metal part 9 returns to almost the same position as before cutting between each of the adjacent external lead bodies 8 or between other parts such as the connecting part 11 and the external lead body. And, the tip of this resin flow stopper metal part 9,
The resin mold line 12 is indicated by a dotted line.
The end surface 13 in contact with the resin mold part is processed so as to be located along the mold line or at a position slightly shifted outward from the resin mold part (for example, o, o a m ).

FIG. 3 shows a semiconductor device that is resin-sealed using a lead frame having such a structure. In FIG. Shows the state just before cutting along. 15
is a resin mold.

That is, in this case, if the external lead body 8 is cut at a sufficient position of the necessary length along with the resin flow stopper metal part at the position of the cutting line 14, these can be released from the outer frame 1o. can. It is also possible to perform the cutting after the external lead body 8 is previously formed into a convenient shape as a single semiconductor device. As shown in FIG. 3(b), after cutting the external lead body 8 and the resin stopper metal part 9 in plural along the cutting line 14 on the same line, the resin stopper metal remaining between each external lead body The portion 9 can be separated from the main body device by applying an external force using a predetermined jig that can apply an external force only to this portion.

In this way, as is clear from Figures 2 and 3, Figure 1 (
For the lead frame having the structure shown in (a), the cutting position is far enough forward from the part of the resin mold 15 that the metal part is cut from the external lead over the necessary length when forming the external lead during punching. After that, it is inserted between the outer leads or between the outer leads and the support, etc., by pushing it into almost the same position as before cutting, either during the molding process or by an appropriate molding process after cutting. Therefore, it is possible to almost completely prevent resin debris, etc., from flowing out because the gap is sufficiently finer than the gap between the mold protrusion and the lead in the dam block method shown in FIG. 1(b). In addition, by applying processing such as pressure stamping with a very small V-shape to the edge of the entire or both sides of the resin flow stopper to widen the area of the resin flow stopper, the effect of preventing resin from becoming flushed will be further increased. .

As explained above, by using a lead frame having the structure according to the present invention, it is possible to ensure that the resin does not flow out into unnecessary parts during the resin sealing process, and there is no need for a process to remove the resin, and it is possible to achieve extremely high reliability and manufacturing. A highly efficient resin-sealed semiconductor device can be obtained.

[Brief explanation of drawings]

Figures 1 (a) and (b) are conceptual diagrams showing how to prevent resin from flowing between external leads in a conventional lead frame, and Figures 2 (a) and (b) are diagrams showing the lead frame structure of an embodiment of the present invention. FIGS. 3(a) and 3(b), which are perspective views showing the manufacturing process, are schematic diagrams of a semiconductor device using a lead frame according to an embodiment of the present invention. 8...External lead, 9...Resin stopper metal part, 10...Outer frame, 11...Connection part, 12...Mold Line, 13...
End face of resin-fixed metal part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] 1. A lead frame comprising a plurality of lead bodies, and having a metal portion between each of the lead bodies that extends from the outer frame to the vicinity of the resin mold line and is cut from each of the lead bodies.