JPH10326856A - Lead frame and production of semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame and a method for producing a semiconductor device by which a small semiconductor device that has many leads and is hard to be short circuited during fixation to a substrate can be produced easily and efficiently. SOLUTION: In a lead frame provided with a plurality of leads 10, an island 14 for mounting a semiconductor chip and a tie bar 13 for connecting the leads 10, a bending part c is provided midway of the lead 10 to make an arrangement pitch of the lead 10 larger on the far-side compared to that on the near-side to the island 14. The semiconductor chip mounted on the island 14 and its periphery are packaged by resin molding, and then the tie bar 13 among the leads 10 is cut off in parallel along the peripheral edge of the lead 10 and removed thereafter. Projections 14a and 14b are formed on the side of the island 14, and they are pressed down to a stage during wire bonding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for mounting a semiconductor chip and a method for manufacturing a semiconductor device using the same.

[0002]

2. Description of the Related Art Generally, a semiconductor chip in which various circuits such as a transistor, a diode, and an integrated circuit (IC) are formed is provided with a necessary number of leads in a final stage of manufacturing, and a resin for protection. To form a completed semiconductor device. In this step, a metal lead frame having an original lead shape and a portion for attaching a semiconductor chip is used. The part for attaching a semiconductor chip is called an island and is formed at the tip of one lead. Other leads are formed such that the tips are located near the island.

A plurality of bonding pads connected to internal circuits are provided on the upper surface of a semiconductor chip for input or output. After the semiconductor chip is fixed to the island with an adhesive, it is connected to the tip of the lead by wire bonding. Depending on the circuit formed inside, there is also a semiconductor chip having a configuration in which, for example, input / output terminals, power supply terminals, etc. are led out from the lower surface, and such a semiconductor chip is fixed to the island by a conductive adhesive. , And at the same time, it is electrically connected to one lead. In the case of a semiconductor chip having no terminals exposed on the lower surface, one bonding pad may be connected to the periphery of the island by a wire.

[0004] The resin mold is formed so as to enclose the tip of the semiconductor chip, the island and the lead.
Of the leads, a portion existing inside the resin mold is called an inner lead, and a portion existing outside the resin mold is called an outer lead.

In order to improve mass productivity, the steps of fixing a semiconductor chip to an island, connecting a semiconductor chip to a lead, and forming a resin mold are not performed individually for each semiconductor chip, but one step is often performed. It is desirable to perform the processing continuously or in parallel for the semiconductor chips. Therefore, a large number of pairs of islands and leads are regularly formed in parallel on one lead frame. All leads are connected at the proximal end,
In order to prevent the bending of the lead frame and the fluctuation of the interval between the leads, the connection is also made at an intermediate portion between the base end and the tip. The part connecting the intermediate parts is called a tie bar.

FIG. 5 shows a conventional lead frame with a resin mold formed. In FIG. 5, 27 is a resin mold, 21a and 21b are outer leads 21 and 23 of one lead 20 and tie bars. The inner leads are buried in the resin mold 27 and are not shown in the drawing. Also, only a part of the lead frame is shown here, and a portion connected to the left and right and a base end of the lead 20 are omitted. In this example, one semiconductor device has three leads 20.

[0007] The tie bars 23 connecting the leads 20 are cut off, and the outer leads 21 are cut off at the base end side, whereby individual semiconductor devices are separated. The outer lead 21 of the separated semiconductor device is bent along the outer surface of the resin mold 27 as necessary. The completed semiconductor device is mounted on a substrate together with other components. For attachment to the board, solder is used to connect the wiring pattern formed on the board to the outer leads 21 and to firmly fix the semiconductor device.

It is desirable that the semiconductor chip is small and the semiconductor device is small, and the arrangement pitch of the inner leads (A in FIG. 5) is set small. On the other hand, since solder is used for mounting to the board, the arrangement pitch (B in FIG. 5) of the portion 21b of the outer lead 21 far from the island needs to be set wide in order to prevent a short circuit. Therefore, not all the leads 20 are formed in a straight line, but at least the leads located outside are formed so as to have a bent portion.

A lead frame is formed by punching a metal plate into a desired shape. Conventionally, as shown in FIG. 5, a part of a tie bar 23 connecting the leads 20 is formed as a bent portion 21c of the lead 20. The dual use simplifies the configuration. As a result, the arrangement pitch of the outer leads 21 changes with the tie bar 23 as a boundary,
a is equal to the pitch A of the inner lead,
Has a larger pitch B. FIG. 6 is an enlarged view of the lead 20 after the tie bar 23 has been cut off. Only the portion of the tie bar 23 that connects the adjacent leads is cut away, and a portion remains as the bent portion 21c of the two outer leads.

When the number of leads to be attached to the semiconductor chip is as small as about three, even if the leads are bent, a portion 21b having a large pitch and a portion 2 having a small pitch between adjacent leads.
1a will not approach. Therefore, the tie bar 23
Can be cut parallel to the edge of the lead 20 to keep the space between the leads at the resection site wide.

However, when the number of leads to be attached to the semiconductor chip increases, by bending the leads, a portion having a large pitch of one lead approaches a portion having a small pitch of an adjacent lead. FIG. 7 shows a lead frame when four leads are attached, and FIG. 8 shows an enlarged view of the lead 20 after the tie bar 23 has been cut off. In this case, not only the outer two leads but also the inner two leads have the bent portions 21c, and the inner two lead portions 21b are close to the outer two lead portions 21a. doing. Therefore, in order to increase the interval between the leads after the tie bar 23 is cut off, the tie bar 23 must be cut obliquely, not parallel to the edge of the lead 20, as shown in FIG.

[0012] However, there is a limit to widening the interval between the leads of the tie bar excision portion even if the oblique cutting is performed. In addition, strict alignment is required to cut diagonally, and if the alignment is not accurate, the intervals between the leads will not be uniform, and there will be places where the predetermined intervals are not reached. If the spacing between the leads is small, the solder may swell and the adjacent leads may come into contact with each other upon mounting to the substrate, which may cause a short circuit.

In order to prevent the short circuit between the leads, an electrically insulating resin is applied to the surface of the lead where the tie bar has been cut to form an insulating coat. In the example of FIG. 8, an insulating coat is formed in a portion surrounded by a broken line.

[0014]

The method of forming an insulating coat on a cut portion of a tie bar is useful for securing insulation between leads. However, the formation of the insulating coat must be performed after the tie bar has been cut, in other words,
This must be performed individually for each semiconductor device. For this reason, the manufacturing efficiency of the semiconductor device is inevitably reduced not only by simply increasing the number of steps. In addition, in the case of a semiconductor device using a light-to-electric conversion element such as a light emitting diode, a light receiving IC, and a photo interrupter, there is a possibility that the resin of the insulating coat may protrude and block the light entrance and exit.

Further, it is necessary to perform strict alignment for cutting the tie bar obliquely, and it is necessary to increase the processing accuracy of the lead frame to enable this. For these reasons, the structure of the conventional lead frame is an obstacle to reducing the cost of manufacturing the semiconductor device and improving the yield.

The bonding of the semiconductor chip to the island and the wire bonding are performed by placing the lead frame on a flat stage and pressing the tie bar side of the inner lead from above with a pin. FIG. 9 shows an island viewed from the side when wire bonding is performed. In FIG. 9, 31 is an island, 32 is an inner lead, 33
Is a semiconductor chip, 34 is a bonding pad, 35 is a wire, 36 is a stage, 37 is a capillary tool, 38
Is a pin for pressing. Normally, Island 3
1. Both the leads 32 are in close contact with the upper surface of the stage 36,
The semiconductor chip 33 is also in close contact with the upper surface of the island 31.

In this state, the capillary tool 37 is lowered, and the wire 35 protruding from the tip is pressed against the bonding pad 34 with a force that does not damage the semiconductor chip 33. Then, an ultrasonic wave is applied to the tip of the wire 35 from the capillary tool 37 to fix the wire 35 to the bonding pad 34. Next, the capillary tool 37 is moved and lowered onto the lead 32, and similarly, force and ultrasonic waves are applied to fix the wire 35 to the lead 32 and cut it.

However, since the island is located farther from the tie bar than the tip of any other lead, the tip of the island is easily lifted and separated from the upper surface of the stage. The state in which the tip of the island 31 is separated from the stage 36 is shown by a chain line in FIG. In this state, the semiconductor chip 3
Even if 3 is fixed to the island 31, they do not come into close contact with each other and cannot be firmly fixed.

The tip of the island 31 is the stage 3
If wire bonding is performed in a state separated from 6, the island 31 bends, so that a sufficient force is not applied to the wire 35 and ultrasonic waves are also dissipated. Therefore, the bonding pad 34 and the wire 35 cannot be connected well. Wire 3 around the island 31
5 is connected to the island 31 and the wire 3
5 cannot be connected well.

In order to prevent the semiconductor chip from floating, when the semiconductor chip is fixed to the island or wire-bonded, the tip of the island is pressed from above by another pin. In FIG. 9, reference numeral 39 denotes the pin.
Press down on. Therefore, the area of the island 31 is
The area required for mounting the semiconductor chip is set to be larger than that of the semiconductor chip, and the resin mold is increased accordingly, and the semiconductor device as a finished product is also becoming larger.

The present invention has been made in view of the above problems, and can easily and efficiently manufacture a small-sized semiconductor device having a large number of leads and in which the leads are hardly short-circuited when mounted on a substrate. It is an object to provide a method for manufacturing a lead frame and a semiconductor device.

[0022]

In order to achieve the above object, the present invention provides an island for mounting a semiconductor chip, an end connected to or close to the island, and a first island close to the island. In the second area, which is substantially parallel to each other at the first pitch, and in the second area adjacent to the first area and remote from the island, the second area larger than the first pitch
In a lead frame including a plurality of leads arranged substantially in parallel with each other at a pitch of and a linear tie bar connecting the plurality of leads, the tie bar connects the plurality of leads in the first region.

At least one of the leads is connected to the island, and the other end is located near the island. These leads are arranged substantially in parallel, and the arrangement pitch changes on the way, and the side farther from the island is larger than the side closer to the island. The tie bar connects the leads at a portion where the arrangement pitch of the leads is small, that is, a portion closer to the island than a portion where the pitch changes.
Therefore, the length of the portion of the tie bar existing between the adjacent leads is determined only by the pitch of the lead at the portion near the island, regardless of how the arrangement pitch of the leads changes. .

By cutting the tie bar parallel to the edge of the lead, substantially the entire tie bar existing between the leads is easily removed. As a result, the interval between the portions connected by the tie bars of the adjacent leads is substantially equal to the interval between the portions that are not connected, and even if the leads slightly move due to an external force, the adjacent leads hardly come into contact with each other.

In the lead frame having the above structure, the first
May be substantially perpendicular to the plurality of leads, and the plurality of leads may be bent on the boundary. The lead will have a bend to effect a change in the array pitch. The bent portion of each lead is located at a substantially equal distance from the island and exists on a straight line. For this reason, the interval between the bent portions of the adjacent leads becomes narrower, but since the tie bar connects the leads at portions other than the bent portion, the interval between the bent portions after the tie bar is cut does not become narrower. Further, the bent portion does not hinder the cutting of the tie bar. In addition, the length of the lead can be reduced as compared with the case where the lead is bent at a position at a different distance from the island.

The plurality of leads may be formed symmetrically with respect to a straight line passing through the island, except for a portion closer to the island than the tie bar. The length of the bent portion for causing a change in the arrangement pitch of the leads becomes symmetrical, and it is possible to minimize the narrowing of the interval between the bent portions of the adjacent leads.

It is preferable to provide a lead frame with a plurality of sets each composed of an island and a plurality of leads and connected by tie bars. Many semiconductor devices can be manufactured at one time.

According to the present invention, a semiconductor chip having a bonding pad is fixed to an island by using the above-mentioned lead frame, and an end of a plurality of leads not connected to the island is connected to the bonding pad by a wire. The semiconductor device is manufactured by sealing the ends of the lead and the island and the leads with a resin mold, and cutting and removing the tie bar portions existing between the leads in parallel with the edges of the leads. I do. By cutting the tie bar in parallel with the edge of the lead, the portion of the tie bar existing between the leads can be almost completely removed, so that the interval between the leads of the semiconductor device can be kept wide. Also, the tie bar can be easily removed.

In order to achieve the above object, the present invention further provides a substantially rectangular island for mounting a semiconductor chip, and is connected to a first edge of the island and substantially perpendicular to the first edge. In a lead frame comprising a first lead extending in a direction and a plurality of second leads having ends proximate to the island and extending in substantially the same direction as the first lead, the island is substantially parallel to the first lead. It is assumed that the second edge has a protrusion.

The protruding portion can be used as a portion to be held down by a pin in order to prevent the island from floating when the semiconductor chip is fixed to the island or wire-bonded. Also, it can be used as a part to be connected to a wire. Therefore, the size of the island excluding the protrusions can be reduced to a minimum size for mounting the semiconductor chip.

In a normal case, a part of the second lead is provided along the second edge of the island, so that the width of the island including the protrusion, that is, the length in the first edge direction is set to the outside. The distance may be equal to or less than the distance between the two second leads. Therefore, providing the protrusion on the second edge of the island does not affect the size of the resin mold, and does not increase the size of the semiconductor device.

In the present invention, a semiconductor chip having a bonding pad for input or output on an upper surface is fixed to an island using the above-mentioned lead frame, and the end of the island and the second lead are placed on a stage. The semiconductor device is manufactured by pressing the protrusion from above and connecting the bonding pad and the end or protrusion of the second lead with a wire. Since the wire bonding between the bonding pad and the lead or the connection between the island and the semiconductor chip can be reliably performed, a highly reliable semiconductor device can be manufactured. Further, since the island is small, the obtained semiconductor device is small. become.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which a resin mold 7 is formed on a lead frame 1 according to one embodiment of the present invention. The lead frame 1 is formed by removing unnecessary portions from an electrically conductive metal plate by punching or etching.

The lead frame 1 is for attaching four leads to each of a large number of semiconductor chips, and has a large number of band-shaped leads 10 in four groups.
All leads 10 are arranged in the same direction,
At the base end, they are connected by a wide connecting portion 15 orthogonal to these. All the lead groups are regularly arranged at a constant pitch. Through holes 15a for indicating the positions of the groups are formed in the connecting portion 15 at the constant pitch.

The tip of the lead 10 is buried in the resin mold 7, and all the leads 10 have a straight tie bar 13 perpendicular to them at an intermediate portion between the tip and the base.
Are linked by The tie bar 13 is connected to the connecting portion 15.
Of the lead 10 by the lead frame 1
This is to prevent the bending of the lead 10 and the fluctuation of the interval between the leads 10. The tie bar 13 does not form a part of the lead 10 and is cut off later.

FIG. 2 is an enlarged view of a part of the lead frame 1 which will be one semiconductor device, and FIG. 3 shows a state after the resin mold 7 is formed thereon. As shown in FIG. 2, the tip of one of the four leads 10 is formed large as an island 14 for mounting a semiconductor chip. The other ends of the four leads 10 are located near the island 14. A portion 12 of each lead 10 located above the broken line in FIG.
Are the inner leads covered by the resin mold 7 in FIG. 3, and the portion 11 below the broken line is the outer lead located outside the resin mold 7.

Although not shown, the semiconductor chip mounted on the island 14 has four terminals including input / output terminals, one of which is exposed as a lower surface, and the other three are formed on an upper surface. Connected to the three bonding pads. The semiconductor chip is fixed to the island 14 by a conductive adhesive, and the bonding pad and the inner lead 12 are connected by, for example, a gold wire. Thus, the four terminals are electrically connected to the different leads 10, respectively.

The tip of the four leads 10 at which the island 14 is formed is optional, and the connection between the wire and the inner lead 12 is also optional. These may be determined according to the positions of the bonding pads of the semiconductor chip so that wire bonding can be easily performed. In particular, it is preferable that the connection portion of the inner lead 12 is determined in consideration of the resin injection direction so that the resin can be injected without damaging the wire during the formation of the resin mold.

The lead frame 1 has only three terminals, and each terminal is connected to a bonding pad formed on the upper surface.
The present invention is also applicable to a semiconductor chip that does not need to be connected to 0. In this case, the lead connected to the island 14 functions as a mere support member for fixing the island 14 until the resin mold 7 is formed. Therefore, the semiconductor chip may be fixed to the island with an insulating adhesive instead of a conductive adhesive.
The outer leads 11 of the leads connected to are cut and removed.

The lead frame 1 can also be applied to a semiconductor chip having four bonding pads on the upper surface and all four terminals connected to the bonding pads. In this case, the semiconductor chip is fixed to the island 14 with a conductive or insulating adhesive, and one of the bonding pads is connected to a lead connected to the island 14 by a wire. This lead is, of course, a resin mold 7
Store after forming.

The island 14 is substantially rectangular, and the protrusions 14a, 14a
b is formed. The size of the island 14 excluding the protrusions 14a and 14b is set to the minimum size required for mounting the semiconductor chip. Projection 14
a and 14b are provided near the edge facing the edge connected to the lead.

One of the protrusions 14a is straight, and its edge is continuous with the edge of the island 14. The other protrusion 14 b is bent in a direction away from the lead 10. The tip of the projection 14b and the projection 14a are used as a part pressed by a pin when the semiconductor chip is fixed to the island 14 and / or when wire bonding is performed. The base end of the projection 14b can also be used as a part for connecting to a wire.

Outer two of the four inner leads 12
The book reaches the vicinity of the protrusion 14a or 14b, and is along the edge of the island 14 on which the protrusions 14a and 14b are formed. As described above, when the inner lead 12 is arranged along the island 14, a portion to be connected to the wire can be freely selected. Therefore, the lead frame 1 can be used for various semiconductor chips having different positions of the bonding pads, and the position of the connection portion with the wire is determined in consideration of the resin injection direction at the time of forming the resin mold. Can be.

The inner leads 12 are formed at the same pitch A and in parallel with each other. This pitch A corresponds to lead 1
0 is located near the island 14,
It is set small. This makes it possible to form the resin mold 7 to the minimum size necessary to protect the semiconductor chip and the tip of the lead 10. A portion 11a of the outer lead 11 that is closer to the resin mold 7 (hereinafter, referred to as a near portion) is formed on an extension of the inner lead 12, and has the same pitch A as the inner lead 12.

On the other hand, a portion 11b of the outer lead 11 far from the resin mold 7 (hereinafter referred to as a far portion)
The pitch B of the inner leads 12 needs to be larger than the pitch A of the inner leads 12 in order to facilitate attachment to the substrate and to prevent a short circuit due to solder at that time. Therefore, a bent portion 11c is formed in the outer lead 11 in the middle. The displacement between the near portion 11a and the far portion 11b of the outer lead 11 due to the bent portion 11c is equal to the outer two positions.
The book is larger than the two inner ones. The four outer leads 11 are set to be symmetrical left and right, and by providing such a symmetrical relationship, the distant portions 11 of the two inner leads are provided.
The amount by which b is shifted outward can be equalized and minimized.

The bent portions 11c of all the leads 10 are formed at the same distance from the island 14, so that the distance between adjacent leads is smaller in the vicinity of the bent portion 11c than in any other portion. However, the bent portions 11c having the narrowest interval are designed to have a sufficient size so as not to come into contact with each other even when the solder is raised when the solder is mounted on the board. Specifically, in order to minimize the decrease in the interval, the opposing edges of the bent portion 11c are set to be oblique with respect to the edges of the other portions so as to be substantially parallel to each other. Since the entire lead frame 1 is formed at a time by punching or etching, there is no variation in the interval between the leads 10, and the interval between the bent portions 11c is as designed.

The tie bar 13 is formed so as to connect the outer lead 11 between the island 14 and the bent portion 11c, that is, the near portion 11a having the same pitch as the inner lead 12. The tie bar 13 is cut off after forming the resin mold. The region of the tie bar 13 to be cut is shown by hatching in FIG. The tie bar 13 can be cut at a position parallel to the edge of the near portion 11a of the outer lead 11 and at a position close to the edge, and cuts as such. A slightly wider portion 11d will be formed in the near portion 11a after the tie bar 13 is resected.
The interval of 1d is equal to or greater than the interval of the adjacent bent portion 11c.

Even if the solder swells when mounting on the substrate, the portion 11d after the tie bar is cut off is not bent.
Like 1c, they do not contact each other, and short-circuiting of the leads 10 on the substrate is prevented.

By cutting the tie bar 13 in parallel with the edge of the lead 10, it is not necessary to align the cutting edge of the cutting device with the lead frame 1 very strictly. For example, the direction along the lead 10 (the vertical direction in FIG. 3)
Even if there is some displacement, the position where the tie bar 13 is cut is not affected at all, and the length of the cut tie bar 13, that is, the interval between the portions 11 d is as designed. Also, even if there is a slight displacement in the direction perpendicular to the lead 10 (the left-right direction in FIG. 3), the displacement equally affects both cutting positions of the tie bar. Length, ie, part 1
The interval between 1d is as designed.

When the alignment is simplified, the tie bar 1
The time required for cutting 3 is reduced, and the manufacturing efficiency of the semiconductor device is improved. Further, it is not necessary to form the lead frame 1 with particularly high processing accuracy, and the manufacture of the lead frame itself becomes easy.

The tie bar 13 is preferably formed near the center of the near portion 11a of the outer lead 11 in order to prevent the cutting edge of the cutting device from touching the resin mold 7 and the bent portion 11c during cutting. When forming the near portion 11a long, if the tie bar 13 is separated from both the resin mold 7 and the bent portion 11c to some extent, the tie bar 13 is moved to the near portion 11a.
It may be formed anywhere in a.

After fixing the semiconductor chips to all the islands 14, wire bonding each semiconductor chip to the leads 10, and sealing all the semiconductor chips with the resin mold 7, in this order, the tie bars 13 are removed as described above. The outer leads 11 are cut off at an appropriate distance from the resin mold 7 to obtain a large number of semiconductor devices at once. If necessary, the outer lead 11 is bent along the lower surface of the resin mold 7 to complete the semiconductor device.

When the semiconductor chip is fixed and / or wire-bonded, the protrusions 14a and 14b are pressed by pins against the stage on which the lead frame 1 is mounted, thereby preventing the tip of the island 14 from rising. Therefore, the semiconductor chip is firmly fixed to the island 14, and the wire bonding between the semiconductor chip and the lead 10 is reliably performed.

In the semiconductor device manufactured as described above, the outer leads are spaced apart from each other at a sufficient interval despite the large number of leads, and even if the insulating coat is not formed on the cut portion or the bent portion of the tie bar, the substrate can be formed. This prevents the leads from coming into contact with each other and causing a short circuit when they are fixed. For fixing to the substrate and connecting to the wiring pattern formed on the substrate, not only manual soldering but also an efficient soldering method such as dip soldering or flow soldering can be adopted.

As shown in FIG. 2, the protrusions 14a, 14a
b, ie, the length in the direction perpendicular to the inner leads 12 (the left-right direction in FIG. 2) is set substantially equal to the interval between the two outermost inner leads 12. The length (in the vertical direction in FIG. 2) along the inner lead 12 is minimized to the extent that the semiconductor chip is mounted. Therefore,
The resin mold 7 can be formed small, and the size of the semiconductor device also becomes the minimum required.

FIG. 4 shows a state in which the semiconductor chip 8 is attached to the island 14 ′ whose shape has been partially changed. The other parts of the lead frame having the islands 14 'are the same as the corresponding parts of the lead frame 1 described above, and redundant description will be omitted. The island 14 ′ is replaced with the protrusion 1 b instead of the protrusion 14 b of the island 14 of the lead frame 1.
4c. The protrusion 14 is bent in a direction approaching the inner lead 12, and the edge of the base end is on the extension of the edge 14 d of the island 14 ′ and the edge 1
4d.

Reference numeral 8a denotes a bonding pad formed on the upper surface of the semiconductor chip 8, and 9 denotes a bonding pad.
This is a wire that connects a to the tip of the inner lead 12 or the protrusion 14c. For example, the semiconductor chip 8 is a photo IC having four terminals, and all terminals are connected to bonding pads 8a on the upper surface. One of the four bonding pads 8a is connected to the tip of the protrusion 14c, and the other three are connected to different inner leads 12, respectively.

The shaded portion is a portion which is held down by pins when the semiconductor chip 8 is fixed or wire-bonded. As described above, when the base end of the projection 14c is continued to the tip of the island 14 ', the island 1
There is no need to adjust the relative position of the pin in the lateral direction (the left-right direction in FIG. 4) with respect to 4 ′, so that the fixing of the semiconductor chip and the wire bonding become easier.

When the tip of the projection 14c is connected to the bonding pad 8a on the upper surface of the semiconductor chip 8 by a wire, the risk of wire bonding failure is greatly increased when the island is lifted. By performing the wire bonding while pressing the protruding portions 14a and 14c as in the present invention, it is possible to make the ultrasonic wave act satisfactorily and realize the reliable wire bonding.

Although an example of a lead frame for attaching four leads to a semiconductor chip has been described here, the present invention can be applied to a case where more leads are attached. The length of the tie bar to be cut is determined by the interval between the inner leads and does not depend on the interval between the bent portions. Therefore, even if the number of leads is increased, the effect of the lead frame of the present invention for preventing short circuit is not diminished. As described above, the outer leads are desirably formed symmetrically. When attaching an odd number of leads to the semiconductor chip, it is preferable that the center lead be straight without a bent portion.

In the above embodiment, the bent portions of all the leads are formed at substantially the same distance from the island, but this is to prevent the outer leads from becoming excessively long. When the outer lead can be made longer, the bent portion can be formed at a position different in distance from the island. In this case, the distance between the bent portions of the adjacent leads increases, and even when a semiconductor device having a large number of leads is manufactured, a short circuit is reliably prevented. In addition, the distance between the island and the tie bar is constant, and cutting of the tie bar is as easy as when the number of leads is small.

It is desirable that the arrangement pitch of the portion of the outer lead far from the island is constant in order to keep the distance between the wiring patterns formed on the substrate constant. However, the arrangement pitch is changed according to the distance between the wiring patterns on the substrate. No problem. The arrangement pitch of the inner lead and the extension of the outer lead, which is close to the island, does not need to be constant, and can be set differently between the leads according to the position of the bonding pad formed on the semiconductor chip. it can. However, these sites should be formed parallel or nearly parallel to each other to facilitate tie bar resection.

In the above description, an example is shown in which one protruding portion, that is, two protruding portions is provided on each of two edges parallel to the lead of the island, but at least one protruding portion is provided as a whole. I just need. However, the provision of the two protrusions as described above can more reliably prevent the island from floating.

[0064]

According to the lead frame of the first aspect, the tie bar can be cut parallel to the edge of the lead, and the lead can be easily cut off. Moreover, since almost the entirety of the tie bar existing between the leads can be removed, the interval between the leads is hardly reduced, and even if the leads slightly move due to an external force, the adjacent leads hardly come into contact with each other. Therefore, when the completed semiconductor device is fixed to the substrate, a short circuit is less likely to occur. This lead frame is suitable for manufacturing a semiconductor device having many leads.

In the lead frame according to the second aspect, the leads do not become unnecessarily long, and contact between adjacent leads is also prevented.

In the lead frame according to the third aspect, the narrowing of the interval between the bent portions of the adjacent leads is minimized, and the possibility that the adjacent leads come into contact with each other is further reduced.

According to the lead frame of the fourth aspect, a large number of semiconductor devices can be manufactured at one time, and the manufacturing efficiency is high.

According to the method of manufacturing a semiconductor device of the fifth aspect, a semiconductor device in which leads are hard to contact can be easily and efficiently manufactured. In particular, the method is suitable for manufacturing a semiconductor having many leads.

According to the lead frame of claim 6,
Since the island can be brought into close contact with the stage by pressing the projection, the semiconductor chip can be securely fixed to the island and / or wire-bonded. Therefore, a semiconductor device free from poor connection can be obtained. Moreover,
Since the size of the island can be reduced to the minimum necessary for mounting the semiconductor chip, the size of the obtained semiconductor device is also reduced.

The semiconductor device according to claim 7 is a small-sized semiconductor device having no connection failure inside.

According to the method of manufacturing a semiconductor device of the eighth aspect, a small-sized semiconductor device having no internal connection failure can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a resin mold is formed on a lead frame according to an embodiment of the present invention.

FIG. 2 is a view showing a part of one semiconductor device of the lead frame of FIG. 1;

FIG. 3 is a diagram showing a state in which a resin mold is formed around the island of the lead frame of FIG. 2 and its periphery.

FIG. 4 is a view showing a part of a lead frame in which the shape of a part of an island is changed.

FIG. 5 is a view showing a state in which a resin mold is formed on a conventional lead frame.

FIG. 6 is a view showing the lead after the tie bar is cut off from the lead frame of FIG. 5;

FIG. 7 is a view showing a state in which a resin mold is formed on another conventional lead frame.

FIG. 8 is a view showing the lead after the tie bar is cut off from the lead frame of FIG. 7;

FIG. 9 is a diagram showing an island viewed from the side when performing wire bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 7 Resin mold 10 Lead 11 Outer lead 11a Outer lead near part 11b Outer lead far part 11c Bent part 12 Inner lead 13 Tie bar 14 Island 14 'Island 14a Projection part 14b Projection part 14c Projection part 15 Connection part

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[Procedure amendment]

[Submission date] March 31, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Deleted

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Deleted

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Deleted

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Deleted

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Deleted

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0070

[Correction method] Deleted

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0071

[Correction method] Deleted

Claims (8)

[Claims] 1. An island for mounting a semiconductor chip, an end continuous with or close to the island, and in a first region near the island, substantially parallel to each other at a first pitch, In a second region adjacent to the first region and far from the island, a plurality of leads arranged substantially in parallel with each other at a second pitch larger than the first pitch, and a straight line connecting the plurality of leads A lead frame comprising a tie bar in a shape of a circle, wherein the tie bar connects the plurality of leads in the first region. 2. The method according to claim 1, wherein a boundary between the first region and the second region is substantially perpendicular to the plurality of leads, and the plurality of leads are bent on the boundary. Item 2. The lead frame according to Item 1. 3. The plurality of leads are symmetrical with respect to a straight line passing through the island except for a portion closer to the island than the tie bar.
The lead frame according to 1. 4. The lead frame according to claim 1, wherein a plurality of sets each including the island and the plurality of leads and connected by the tie bar are provided. 5. A semiconductor chip having a bonding pad for input or output on an upper surface thereof is fixed to the island, and an end of one of the plurality of leads not connected to the island is connected to the bonding pad by a wire. After sealing the semiconductor chip, the island, and the end of the plurality of leads with a resin mold, cut a portion of the tie bar existing between the plurality of leads in parallel to an edge of the plurality of leads. The method for manufacturing a semiconductor device using a lead frame according to claim 1, wherein the semiconductor device is removed. 6. A substantially rectangular island for mounting a semiconductor chip, a first lead connected to a first edge of the island and extending in a direction substantially perpendicular to the first edge,
And a plurality of second leads having an end close to the island and extending in the same direction as the first lead, wherein the island has a second side substantially parallel to the first lead. A lead frame having a protrusion on an edge. 7. A semiconductor chip having a bonding pad for input or output on an upper surface, mounted on the island, a wire connecting the bonding pad to the second lead or the protrusion, and the semiconductor chip 7. A semiconductor device using a lead frame according to claim 6, comprising a resin mold for sealing an end of said island and said second lead. 8. A semiconductor chip having a bonding pad for input or output on an upper surface is fixed to the island, and the end of the island and the second lead is placed on a stage, and the projection is raised from above. 7. The method of manufacturing a semiconductor device using a lead frame according to claim 6, wherein the bonding pad is connected to an end of the second lead or the protrusion by a wire.