JPS6147657A - Lead frame - Google Patents

Abstract

PURPOSE:To improve reliability of semiconductor device by attaching a pellet where bonding pads are arranged almost continuously along opposed two sides of tab. CONSTITUTION:Regarding the second lead 7b which is the second lead counted in the right or left from the centers respective of opposed two sides 3a, 3b of tab 3 or successive leads among the leads 7 corresponding to the external lead 4 extended near the side 3a among two opposed sides of tab 3, the internal end portion is extended up to the position exceeding the left side end 3c and the internal end portion is arranged almost along the left wide end 3c. Thereby, in the case that a pellet 9 where the bonding pads 8 are arranged almost continuously is attached to the tab 3 of lead frame along opposed two sides in the vertical direction for opposed two sides 3a, 3b of tab 3, the internal end portions of leads 7a, 7b, 7c and bonding pads 8a, 8b, 8c can be wire-bonded in the very closed condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a lead frame, and relates to a technique effective when applied to improving reliability of a semiconductor device.

[Background technology]

It is conceivable to form the bonding pads, which are the electrodes of the pellet, in approximately double rows along two opposing sides of the pellet. By forming the pads in this way, compared to the case where the pads are formed along the four surrounding sides, it is possible to expand the operating area without changing the pellet size, and achieve high pellet integration. It is something that can be done.

However, in a resin-sealed semiconductor device formed using a lead frame on which the pellets are mounted, external leads are formed on the side of the pellet where the pads are not arranged (the side without pads). If the inner end of the lead, which is the wire bonding part, is also formed near the non-pad side, the distance between the inner end and the pad is long, so it cannot be used for electrical connection between the two. It has been revealed that there are problems such as the wires made of gold or the like used become long, and contact occurs between the wires or between the wires and pellet corners, which tends to cause short circuits, and the cost increases. The inventors have found that this problem is particularly important when there are two or more leads connected to pads arranged along one side.

In addition, when wire bonding the inner end of the lead and the band that have the above relationship, the angle between the straight line connecting the two and the side of the inner end of the lead becomes an extremely acute angle, so the bonding tool cannot be inserted into the lead. There is also the problem that it is difficult to rest on the edge and bonding errors are likely to occur.

Furthermore, in the molding step of the manufacturing process of the semiconductor device, when molding resin is injected from the side of the band arrangement side of the pellet, the inner end of the lead having the external lead on the side of the non-pad side of the pellet and the side of the band arrangement side of the pellet. The inventor has also discovered that since the wires connecting the pads are connected to cross the direction in which the resin flows, there is a problem in that they are easily washed away by the resin and contact between the wires is likely to occur. Ta.

Regarding lead frames, please refer to the rI published by the Industrial Research Council.
It is described in "C Mounting Technology J" published on January 15, 1980, edited by Japan Microelectronics Association, pages 139 to 140.

[Purpose of the invention]

An object of the present invention is to relate to a lead frame, and to a technique that is effective when applied to improve the reliability of a semiconductor device formed using the lead frame.

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

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, it is a lead frame in which external leads extending perpendicularly to each of two opposing sides of a tab serving as a pellet mounting portion are arranged along the two opposing sides, and the external leads are arranged along the two opposing sides. Using a lead frame in which the inner end of at least the second lead of at least the second grain of wood is positioned beyond the left end or right end of the tab, starting from the respective centers in both directions to the left or right, On the tab of the lead frame, bonding pads are arranged and formed substantially continuously along the two opposing sides, with the two opposing sides of the tab and the opposing band-free side of the pellet being substantially parallel to each other. By attaching the pellet, the pad and the inner end of the lead can be brought close to each other, making it possible to shorten the length of the wire used for electrical connection and at the same time changing the direction of wire connection to match the flow of resin during molding. It is possible to almost match them.

Therefore, it is possible to prevent the wires from coming into contact with each other or with the pellet corners etc. due to the wires being washed away by the resin, thereby achieving the above object.

〔Example〕

FIG. 1 is an enlarged partial plan view showing the features of a lead frame according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing the lead frame of this embodiment.

The lead frame has an outer frame 1 and a partition frame 2 forming a rectangular shape ε, and a tab 3 is connected to the outer frame 1 via a tab suspension lead 4 at approximately the center thereof. External leads 5 are formed on the sides of the two opposing sides 3a and 3b to extend perpendicularly to the two sides 3a and 3b, respectively. An internal lead 7 is formed on the inside beyond the tie bar 6, and the tie bar 6
is connected to the outer frame 1 at both ends to form approximately one unit. Incidentally, a lead frame is usually made up of a plurality of lead frames having the same shape connected in the vertical direction in the figure.

The features of this embodiment are as shown in the partial plan view of FIG.
It is on its internal lead 7.

That is, the inner lead 7 corresponds to the outer lead 4 extending to the side of 3a of the two opposing sides of the tab 3.
Of these, the left or right direction (in this figure, 3
Only the left direction of a is shown. ), the inner end of the lead (in this figure, only the third lead 7C) is extended to a position beyond the left end 3C of the tab 3. The inner end portion is arranged substantially along the left end 3C.

The lead frame having the above-mentioned shape has two opposing sides 3a and 3b of the tab 3 shown by two dotted lines in the vertical direction (only one side is shown in this figure). ) When attaching a pellet 9 in which bonding bands 8 are arranged substantially continuously along By performing wire bonding with 80 respectively, wire bonding can be performed in a very close state.

Furthermore, since the angle at which the straight line connecting the bonding band 8 and the inner end of the lead intersects with the side of the inner end can be made relatively gentle, it can be said that the bonding tool of the wire bonder can be easily placed on the lead.

Furthermore, in the package molding process, when molding resin is injected from the side of the bullet where the bonding bands are arranged, that is, from the side of the left end of the tab, the connecting portion of the tab suspension lead 4 with the outer frame 1 is usually A nearby mold (not shown).

), the resin flows in the direction along the tab suspension lead 4. The inner ends of the main leads of the lead frame of this embodiment extend in the same direction as the tab suspension leads 4, and bonding wires (not shown) are connected approximately on the extended line thereof. Therefore, the influence of the pressing force accompanying the flow of the mold resin is very small.

In this embodiment, only the wire connecting the first lead 7a and the bonding pad 8a intersects the flow direction of the molding resin, but in this case, the wire is short and other nearby Since there are no leads, contact between the wires is unlikely to occur, so there is no particular problem.

In addition, since the internal leads of the second lead 7b and third lead 7C in particular have a long shape, the bonding area with the molded resin after the package is completed is expanded, and the leads are firmly fixed. As a result, moisture resistance is also improved.

〔effect〕

(1) A lead frame in which external leads extending perpendicularly to each of two opposing sides of a tab are arranged along the two opposing sides, the lead frame being arranged at the center of each of the two opposing sides. A band is formed along two opposite sides of the tab by positioning the inner end of at least the second or more lead beyond the left end or right end of the tab with respect to both the left and right directions from the starting point. When attaching the pellet so that the two opposing sides of the tab and the opposing butt-free side of the pellet are substantially parallel, the inner end of the lead and the pad can be brought close to each other.

(2) According to (11) above, if the resin injection gate of the molding die is provided on the side of the band arrangement side of the mounting pellet, the flow of the injected resin in the mold cavity and the arrangement direction of the tip leads can be almost matched.

(3) According to (1) above, when wire bonding is performed between the inner end of the lead, which is an electrical connection part, and the band of the pellet, the wire connection direction and the extension direction of the tip lead can be made to substantially match.

(4) With (2) and (3) above, it is possible to prevent the wire from bending due to the pushing force associated with the flow of the injected resin, so electrical failures may occur due to contact between wires or contact between the wire and a pellet corner, etc. can be prevented.

(5) According to (2) above, even if the lead is thin, it is possible to prevent the lead from bending due to the pressing force accompanying the flow of the injected resin.

(6) Due to +11 above, the angle between the straight line connecting the inner end of the lead and the pad and the intersecting side of the inner end can be made gentler, so that the bonding tool rests on the inner end of the lead. This can improve wire bonding errors and prevent wire bonding errors.

(7) As shown in (11) above, when the inner end of only the first lead is located near the opposite side of the tab, the wire that electrically connects the inner end of the lead and the pad is Although the wire connection direction and the flow of the injected resin during molding intersect, since the lead is the only lead in this relationship, it is possible to prevent the occurrence of contact between the wires.

(8) According to (1) above, the length of the internal leads is extended, so the bonding area between the resin and the leads can be expanded after the package is completed, and the lead fixing strength can be increased.

(9) According to (8) above, it is possible to prevent the adhesive between the lead and the resin from peeling off, so that the moisture resistance of the semiconductor device can be improved.

Although the invention made by the present inventor has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the embodiment, the inner end of the first lead is positioned on the side of the tab, but the invention is not limited to this. It may be positioned beyond the right edge.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to a lead frame for a so-called DIP type semiconductor device, which is the background field of application, but the invention is not limited to this. For example, if it is used to manufacture a semiconductor device that mounts a pellet in which a bonding band is formed almost continuously along two opposing sides, various resin-sealed semiconductor devices such as a flanto passocage type can be used. This is an effective technology when applied to lead frames used in manufacturing.

[Brief explanation of drawings]

FIG. 1 is an enlarged partial plan view showing the features of a lead frame according to an embodiment of the present invention, and FIG. 2 is a schematic plan view showing the lead frame of this embodiment. 1... Outer frame, 2... Partition frame, 3... Tab, 3a,
3b... Side, 3C... Left end, 4... Tab hanging lead, 5... External lead, 6... Tie bar, 7...
・Internal lead, 7a...first lead, 7b...second
'J-do, 7C...3rd lead, 8.8a, 8b,
8c --- Ponding pad. Figure 2

Claims (1)

[Scope of Claims] 1. A lead frame in which external lead portions extending perpendicularly to each of the two opposing sides of the tab are arranged along the two opposing sides, A lead frame in which the inner end portions of at least a second or more lead are positioned beyond the left end or right end of a tab in both the left and right directions starting from the center of each of two opposing sides. 2. The lead frame according to claim 1, wherein a tab suspension lead is connected to approximately the center of the left end and right end of the tab. 3. The lead frame according to claim 1 or 2, wherein the lead frame is used for a dual in-line semiconductor device.