JPH11214606A - Resin-sealed semiconductor device and lead frame - Google Patents

Abstract

(57) Abstract: A resin-encapsulated semiconductor device in which a lower portion of a lead functions as an external electrode is provided to achieve higher density and improved reliability of a semiconductor element. SOLUTION: A die pad 11 supported by a suspension lead 10, a semiconductor chip 12 mounted on the die pad 11, a lead 13, a thin metal wire 14 for electrically connecting the electrode pad and the lead 13, and a suspension lead. 10, a die pad 11, a semiconductor chip 12, a lead 13, and a sealing resin 15 for sealing the fine metal wire 14.
The lower part of the lead 13 functions as the external electrode 16. Since the arrangement pitch of each external electrode 16 is small at the center of the side and large at the corner, the peeling of the lead at the corner where the stress is large is prevented, and the external electrode at the center is increased while increasing the reliability. The number of semiconductor elements is increased to increase the number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed semiconductor device in which a semiconductor chip and a lead frame connected to the semiconductor chip are sealed with a resin, and more particularly to measures for improving reliability.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for smaller and thinner semiconductor products mounted on printed circuit boards for the purpose of reducing the size and weight of devices. To achieve this goal,
For example, a TAB mounting technology using a polyimide tape has been developed. However, even today, resin-encapsulated semiconductor devices in which a semiconductor chip and a lead frame connected to the semiconductor chip are sealed with resin are widely used in general equipment.

Hereinafter, a resin-encapsulated semiconductor device that is currently widely used will be described. FIG. 8 is a cross-sectional view showing an example of a conventional double-sided resin-sealed semiconductor device.

In a conventional resin-encapsulated semiconductor device shown in FIG. 8, a semiconductor chip 103 is mounted on a die pad 102 of a lead frame, and electrode pads (not shown) of the semiconductor chip 103 and inner leads of the lead frame. 1
04 is electrically connected by a thin metal wire 105.
Then, the semiconductor chip 103, the die pad 102, the inner leads 104, and the fine metal wires 105 are
Sealed inside. Then, the outer leads 101 connected to the inner leads 104 and protruding outside the sealing resin 106 become external electrode terminals to be connected to a printed wiring board or the like. In this structure, since the sealing resin 106 exists both above the semiconductor chip 103 and below the die pad 102, there is a disadvantage that the thickness of the entire semiconductor device becomes large.

Therefore, a single-sided sealing type semiconductor device shown in FIGS. 9 and 10 has been proposed. 9 is a cross-sectional view of the conventional single-sided sealed semiconductor device in a cross section where the inner leads 104 are present, and FIG. 10 is a rear view of the conventional single-sided sealed semiconductor device. The materials and functions used in each part shown in FIGS. 9 and 10 are the same as those in FIG. 9 and 10
In the structure of the single-sided sealing type semiconductor device shown in FIG.
Since 06 is present only on the surface of the die pad 102 on which the semiconductor chip 103 is mounted, the thickness of the entire semiconductor device can be reduced.

[0006]

However, the conventional resin-encapsulated semiconductor device shown in FIGS. 9 and 10 has the following problems.

That is, in the case of a semiconductor device of a single-sided sealing type, the inner lead 1 is smaller than a semiconductor device of a double-sided sealing type.
Since the sealing resin does not exist below the inner lead 104, the holding force of the sealing resin 106 with respect to the inner lead 104 is inevitably weakened. Therefore, when a force such as a pulling force acts on the inner lead 104 in the cross section shown in FIG. There is a possibility that the inner lead 104 is easily peeled off from the sealing resin. In particular, when the number of external electrode terminals increases by mounting a large number of semiconductor elements (transistors, etc.) in a semiconductor chip and increasing the number of external electrode terminals, the semiconductor chip is attached to the substrate by soldering or the like due to bending stress applied to the printed wiring board The external electrode terminals of the semiconductor device may be peeled off from the printed wiring board or the sealing resin, or the temperature cycle resistance of the semiconductor device after mounting may be reduced, leading to a reduction in reliability.

The present invention has been made by paying attention to the fact that stress such as thermal stress applied to a semiconductor device becomes more remarkable as approaching a corner portion of the semiconductor device.

A first object of the present invention is to make the arrangement density of external electrodes on one side of a semiconductor device different between a center portion and an end portion (ie, a portion close to a corner portion) of the side, thereby reducing the number of external electrodes. The object is to enhance the bonding force between the sealing resin and the external electrode while increasing the power.

A second object of the present invention is to increase the number of external electrodes while increasing the number of external electrodes by making the area of the external electrode on one side of the semiconductor device different between the center and the end of the side. An object of the present invention is to enhance the bonding force between an electrode and a mounting substrate such as a printed wiring board.

A third object of the present invention is to make it possible to identify the reference position of the semiconductor device by utilizing the shape of the external electrode on each side of the semiconductor device, thereby facilitating attachment to the mounting board. It is to plan.

[0012]

In order to achieve the first object, according to the present invention, there are provided means relating to the first semiconductor device according to claims 1 to 9 and claims 12 to 19 according to the present invention. And means for the first lead frame.

Further, in order to achieve the second object,
According to the present invention, the means relating to the second semiconductor device described in claim 10 and the second semiconductor device described in claim 20 are provided.
And measures concerning lead frames.

Further, in order to achieve the third object,
According to the present invention, means relating to the third semiconductor device described in claim 11 is taken.

According to a first aspect of the present invention, there is provided a semiconductor device having a semiconductor chip having an electrode pad on a main surface and a polygon sealing a peripheral region including the semiconductor chip. And a plurality of leads extending from a position close to the semiconductor chip in the sealing resin to a side end of the sealing resin and at least a part of the lower surface is exposed from the sealing resin. And a connection member for electrically connecting the electrode pads of the semiconductor chip and the leads,
The lower part of the lead functions as an external electrode,
The arrangement pitch of the external electrodes on the back surface of the semiconductor device is smaller at the center of the side than at the corner of the sealing resin.

Thus, since the lower portion of the lead functions as an external electrode, the outer lead conventionally formed so as to protrude outside the sealing resin becomes unnecessary.

Here, when a semiconductor device is mounted on a mounting board such as a printed wiring board by soldering or the like, stress is generated due to a difference in the coefficient of thermal expansion of constituent members of the semiconductor substrate. Also, when mounting a printed wiring board or the like on which a semiconductor device is mounted in the case of a device to be used by screwing or inserting it into a socket, the applied substrate may be slightly deformed, such as being bent by the applied force. As a result, stress is generated in the semiconductor device joined to the mounting substrate. In the corner portion of the semiconductor device where a stress such as thermal stress acts strongly, the arrangement pitch of the leads is large and the presence ratio of the sealing resin to the leads is large.
The holding power of the sealing resin to the leads is large, and the leads can be prevented from coming off and peeling off. On the other hand, in the central portion of the side of the semiconductor device, since the arrangement pitch of the leads is small and the ratio of the sealing resin to the leads is relatively small, the holding force of the sealing resin is weaker than in the corner portion. No problem occurs because the stress acting on the substrate is small. In addition, since external electrodes can be densely arranged in the center of the side of the semiconductor device, the number of external electrodes can be increased.

Therefore, the reliability of the semiconductor device can be improved while increasing the density of the semiconductor elements housed in the semiconductor device.

According to a second aspect of the present invention, in the semiconductor device of the first aspect, it is preferable that the length of the lead is larger at the center of the side than at the corner of the sealing resin.

This makes it possible to reduce the arrangement pitch of the leads at the center of the polygonal side of the semiconductor device while keeping the area of the lower surface of the external electrode to be joined to the mounting substrate large. .

According to a third aspect of the present invention, in the semiconductor device according to the first or second aspect, the width of the lower surface of the external electrode on the back surface of the semiconductor device is set to be smaller than the center of the side of the sealing resin. It is preferable to widen the area.

As a result, a large contact area between the external electrode and the connection terminal of the mounting substrate can be ensured even in a corner portion where the length of the lead is restricted, so that the mounting substrate can withstand a large stress acting on the corner portion of the sealing resin. And the reliability of the connection with the wire.

According to a fourth aspect of the present invention, in the semiconductor device according to any one of the first to third aspects, the area of the lower surface of the external electrode on the back surface of the semiconductor device is equal to the area of the side of the sealing resin. It is preferable to make it larger at the corner than at the center.

This ensures that the contact area between the external electrode and the connection terminal of the mounting substrate at the corner portion of the semiconductor device is increased, so that the reliability of the semiconductor device is improved and the corner portion of the semiconductor device acts. The reliability of bonding with the mounting board against a large stress is improved.

According to a fifth aspect of the present invention, in the semiconductor device according to any one of the first to fourth aspects, a wide portion is provided in a part of the lead on the inner side of the sealing resin. it can.

As a result, the lead can be pulled out or pulled out by the anchor effect of the wide portion against the force for pulling the lead to the side.
Peeling can be prevented.

According to a sixth aspect of the present invention, in the semiconductor device according to any one of the first to fifth aspects, a width of a lower portion of at least a part of the lead is smaller than a width of an upper portion. Can be.

Thus, the lead can be prevented from coming off and peeling off due to the anchor effect of the upper part of the lead against the force pulling the lead downward.

As described in claim 7, in the semiconductor device according to any one of claims 1 to 6, a groove may be formed in a part of the lead.

As a result, the contact area between the lead and the sealing resin is increased, so that the holding force of the sealing resin on each lead is increased, and the reliability of the semiconductor device is improved.

As described in claim 8, in the semiconductor device according to any one of claims 1 to 7, at least a portion of the lead exposed from the sealing resin is subjected to palladium plating. Preferably.

[0032] This improves the conformability with a conductive member such as solder when mounted on a mounting board.

According to a ninth aspect of the present invention, in the semiconductor device according to any one of the first to eighth aspects, at least one of the sides of the semiconductor device is one of the sides.
The shape of one external electrode can be formed so as to be an identification mark of the reference position of the semiconductor device.

Thus, in addition to the functions and effects of claim 1, the reference position at the time of inspection of the semiconductor device or at the time of mounting on a mounting board can be easily and quickly identified, and the manufacture of the semiconductor device can be facilitated. Realize.

According to a second aspect of the present invention, there is provided a semiconductor device comprising:
As described in the above, a semiconductor chip having an electrode pad on the main surface, a polygonal and plate-shaped sealing resin for sealing a peripheral region including the semiconductor chip, and A plurality of leads extending from a position close to the semiconductor chip to a side end of the sealing resin, at least a part of the lower surface is exposed from the sealing resin, and electrically connect the electrode pads of the semiconductor chip and the leads. A connection member for connection, the lower part of the lead functions as an external electrode, and the area of the lower surface of the external electrode on the back surface of the semiconductor device is more at the corner than at the center of the side of the sealing resin. It has a large structure.

This ensures that the contact area between the external electrode and the connection terminal of the mounting substrate at the corner portion of the semiconductor device is increased, so that the reliability of the joint with the mounting substrate against a large stress acting on the corner portion of the semiconductor device is improved. The performance is improved.

According to a third aspect of the present invention, there is provided a semiconductor device comprising:
As described in the above, a semiconductor chip having an electrode pad on the main surface, a polygonal and plate-shaped sealing resin for sealing a peripheral region including the semiconductor chip, and A plurality of leads extending from a position close to the semiconductor chip to a side end of the sealing resin, at least a part of the lower surface is exposed from the sealing resin, and electrically connect the electrode pads of the semiconductor chip and the leads. A connection member for connection, the lower part of the lead functions as an external electrode, and the shape of at least one external electrode on one of the sides of the sealing resin is an identification mark of a reference position of the semiconductor device. It is the structure formed so that it might become.

Thus, the reference position at the time of inspection of the semiconductor device or at the time of mounting on the mounting board can be easily and quickly identified, thereby facilitating the manufacture of the semiconductor device.

A first lead frame according to the present invention is a lead frame for mounting a semiconductor chip having an electrode pad on a main surface, wherein the outer frame has a polygonal shape. And a plurality of chips extending outward from a position close to the mounting region of the semiconductor chip, connected to the outer frame, and arranged such that the arrangement pitch is smaller at the center of the side than at the corners of the outer frame. With the lead.

According to a thirteenth aspect of the present invention, in the lead frame according to the twelfth aspect, the length of the lead can be made larger at the center of the side than at the corner of the outer frame.

According to a fourteenth aspect of the present invention, in the lead frame according to the twelfth or thirteenth aspect, the width of the lower surface of the lead is wider at the corner than at the center of the side of the outer frame. preferable.

According to a fifteenth aspect of the present invention, in the lead frame according to any one of the twelfth to fourteenth aspects, the area of the lower surface of the lead is larger at a corner portion than at a central portion of a side of the outer frame. Larger is preferred.

According to a sixteenth aspect of the present invention, in the lead frame according to any one of the twelfth to fifteenth aspects, a wide portion is provided on a part of the lead on a side close to the semiconductor chip mounting position. be able to.

According to a seventeenth aspect, in the lead frame according to any one of the twelfth to sixteenth aspects, the width of the lower part of at least a part of the lead is smaller than the width of the upper part. Can be.

As described in claim 18, in the lead frame according to any one of claims 12 to 17, a groove may be formed in a part of the lead.

According to a nineteenth aspect, in the lead frame according to any one of the twelfth to eighteenth aspects, at least the lead can be plated with palladium.

According to the twelfth to nineteenth aspects, a lead frame for obtaining the functions and effects of the semiconductor device of the first to eighth aspects can be obtained.

A second lead frame according to the present invention is a lead frame for mounting a semiconductor chip having an electrode pad on a main surface thereof, wherein the outer frame has a polygonal shape. And a plurality of leads extending outward from a position close to the semiconductor chip, connected to the outer frame, and formed such that the area of the lower surface is larger at the corner than at the center of the side of the outer frame. And

As a result, a lead frame for obtaining the function and effect of the semiconductor device according to the tenth aspect is obtained.

According to a twenty-first aspect, in the lead frame according to any one of the twelfth to twentieth aspects, the die pad for mounting the semiconductor chip is connected to the die pad and the outer frame. And a suspension lead for the suspension.

As a result, a lead frame for manufacturing a resin-encapsulated semiconductor device can be obtained by using a widely used manufacturing method.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the resin-sealed semiconductor device of the present invention will be described below with reference to the drawings.

(First Embodiment) FIGS. 1, 2 and 3
FIGS. 3A and 3B are a cross-sectional view, a top view, and a rear view, respectively, illustrating the structure of the resin-sealed semiconductor device according to the first embodiment of the present invention. However, the plan view of FIG. 2 shows a state in which the sealing resin is seen through for easy understanding of the internal structure. FIG. 1 is a sectional view taken along the line II shown in FIG.

As shown in FIGS. 1 to 3, the resin-encapsulated semiconductor device of this embodiment includes a suspension lead 10 which is a part of a lead frame, a die pad 11 supported by the suspension lead 10, and a die pad 11. A semiconductor chip 12 mounted thereon and having a large number of semiconductor elements therein; a lead 13 having a tip disposed near the semiconductor chip 12; an electrode pad (not shown) on the main surface of the semiconductor chip 12; Metal wire 1 as a connecting member for electrically connecting
4 and a sealing resin 15 for sealing the suspension leads 10, the die pad 11, the semiconductor chip 12, the leads 13 and the fine metal wires 14. And lead 13
Functions as an external electrode 16. In other words, the semiconductor device can be mounted on the mounting board by bonding the lower surface of the external electrode 16 and the wiring surface of the mounting board such as a printed wiring board with solder or the like.

Further, as shown in FIG.
0, the step portion 17 for positioning the die pad 11 above the external electrode 16 (ie, upsetting).
Is formed, a lower portion 15a of the sealing resin 15 exists below the die pad 11, and an upper portion 15b of the sealing resin exists above the semiconductor chip 12. That is, the semiconductor chip 12 and the die pad 11 are resin-sealed on both sides.

A plurality of, for example, two grooves 19 are formed on the upper surface side of each lead 13, respectively.
Thereby, the contact area between the sealing resin 15 and the lead 13 is increased, and the holding force of the sealing resin 15 on the lead 13 is increased.

Here, the feature of the semiconductor device according to the present embodiment is that, as shown in FIGS. 2 and 3, the pitch of each external electrode 16 exposed on the back surface of the semiconductor device is not uniform. That is, the arrangement pitch of the external electrodes 16 is small at the center of each side of the semiconductor device, and the arrangement pitch between the external electrodes 16 is increased toward the end of each side which is a corner.

Therefore, according to the semiconductor device of the present embodiment, the arrangement pitch of the external electrodes 16, that is, the arrangement pitch of the leads 13 is increased in the vicinity of the corner of the semiconductor device where stress such as thermal stress acts particularly, that is, in the corner. In addition, by reducing the arrangement pitch of the leads 13 at the center of each side on which the stress acts relatively weakly, the reliability of the semiconductor device as a whole can be reduced without deteriorating the reliability of the entire semiconductor device. The number of electrodes can be increased. For example, even if a large stress acts on the leads 13 at the corners, the sealing resin has a large holding ratio of the sealing resin 15 with respect to the leads 13 at the corners because the ratio of the sealing resin to the leads 13 is large. On the other hand, at the center of each side, the ratio of the sealing resin to each lead 13 is small, and the holding force of the sealing resin 15 is relatively weak. Is small. Therefore, even if a thermal cycle acts after mounting,
The probability that defects such as peeling of each lead 13 from the sealing resin 15 occur is small, and the probability is high that each lead 13
Become almost equal between. That is, the reliability is improved.

In the semiconductor device of this embodiment, as shown in FIG. 1, the step 17 is formed on the suspension lead 10 so that the die pad 11 is located above the external electrode 16. A lower portion 15a of the sealing resin 15 exists below. That is, the semiconductor chip 12
And the die pad 11 are resin-sealed on both sides.
Also, by reducing the height difference on both sides of the step portion 17, there is also an advantage that a thin and highly reliable semiconductor device can be obtained.

However, the present invention is not limited to such an embodiment, and as shown in FIG.
It is needless to say that the same advantage can be obtained by slightly projecting below the lower surface of the sealing resin, or by applying it to a single-sided sealing type semiconductor device in which the lower surface of the die pad 11 is exposed and sufficient. Nor.

Further, since the groove 19 is formed on the upper surface side of the lead 13, the contact area between the lead 13 and the sealing resin 15 increases, so that the holding force of the sealing resin 15 increases. Therefore, a more reliable semiconductor device can be obtained.

In the semiconductor device according to the present embodiment, as shown in FIGS. 1 and 2, two grooves 19 are formed at the tip of the lead 13, and the thin metal wire 14 is formed in a region between the grooves 19. Since the connection is made, the distortion caused by the thermal stress in the connection portion of the thin metal wire 14 with the lead 13 is reduced, and an effect of suppressing a problem such as disconnection of the thin metal wire 14 is also obtained.

Further, the configuration of the semiconductor device according to the present embodiment is smaller than that of the conventional semiconductor device because there are no external leads protruding to the side of the sealing resin 15.

In this embodiment, the die pad 11 has a smaller area than the semiconductor chip 12 to be mounted, but the present invention is not limited to the structure of this embodiment.

FIG. 4 is a view showing an example of a lead frame suitable for manufacturing the resin-encapsulated semiconductor device of the present embodiment. As shown in FIG. 1, a lead frame according to the present embodiment includes a rectangular outer frame 20 and a die pad 1 for mounting a semiconductor chip disposed in a region surrounded by the outer frame 20.
1, a suspension lead 10 for connecting the die pad 11 to the outer frame 20, and a lead 13 extending outward from a position close to the mounting area of the semiconductor chip and connected to the outer frame 20. The suspension lead 10 is provided with a step 17 for upsetting the die pad 11. The arrangement pitch of the leads 13 is smaller at the center of the side than at the corner of the outer frame 20.

Next, a method for manufacturing the resin-encapsulated semiconductor device according to the present embodiment will be described with reference to FIGS.

First, after the lead frame shown in FIG. 4 is formed, the back surface of the semiconductor chip 12 is bonded to the die pad 11 with a conductive adhesive. These lead frames are subjected to palladium plating before mounting a semiconductor chip or after a resin sealing step in order to mount a semiconductor device on a printed wiring board. In the case where palladium plating is performed in advance before mounting the semiconductor chip, the other portions except the inner lead 13 are masked to form the lead 13.
Only the plating may be performed.

Next, the electrode pads (not shown) of the semiconductor chip 12 and the leads 13 of the lead frame are
4 for electrical connection. At this time, the connection portion of the thin metal wire 14 on the lead 13 side is the upper surface of the lead 13 between the two groove portions 19 provided on the lead 13.

Next, the semiconductor chip 12, the die pad 11, the suspension leads 10, the leads 13, and the fine metal wires 14 are sealed with a sealing resin 15 by transfer molding. In this case, the lower portion 15a of the sealing resin 15 exists below the die pad 11, and the upper portion 15b of the sealing resin exists above the semiconductor chip 12, that is,
The semiconductor chip 12 and the die pad 11 are sealed on both sides. The thickness of the sealing resin 15 is such that the lower surface of the lower portion 15 a below the die pad portion 11 is flush with the rear surface of the lead portion 13, and the upper portion 15 b above the semiconductor chip 12 has a loop height of the fine metal wire 14. It seals so that it may become more than thickness. In the resin encapsulation process, the lead 1
It is preferable that the sealing resin 15 is hermetically sealed so that the sealing resin 15 does not go around the back surface side.

Then, the outer leads of the lead frame are cut, and molded so that the side ends of the sealing resin 15 and the ends of the leads are substantially flush with each other.

According to the above steps, the semiconductor chip 1
A highly reliable semiconductor device in which both surfaces of the die pad 2 and the die pad 11 are sealed with resin can be manufactured. The manufacturing process described above eliminates the need for a process of processing the outer leads as compared with the process of forming the conventional semiconductor device shown in FIG. 7, and is excellent in mass productivity.

The lead frame used in the above steps has the arrangement and shape of the external electrodes 16 illustrated in FIG.
The stress applied to the semiconductor device when mounted on the printed wiring board causes the soldered portion of the external electrode 16 and the sealing resin 15
It does not come off or come off.

(Second Embodiment) Next, a second embodiment will be described. FIG. 5 is a back view of the semiconductor device according to the present embodiment. Also in this embodiment, the cross-sectional structure of the semiconductor device is the same as the structure of the first embodiment shown in FIG. Also,
Since the top structure of the semiconductor device of this embodiment can be easily understood from the back view shown in FIG. 5, illustration of the top view is omitted.

As shown in FIG. 5, in the semiconductor device of this embodiment, the arrangement pitch of the external electrodes 16 (that is, the leads 13) on each side is small at the center of each side and large at the corners. This is the same as the embodiment. However, in the present embodiment, the width of the external electrode 16 is wide and short at a corner portion (edge of a side) of the semiconductor device, whereas the width of the external electrode 16 is narrower and longer toward the central portion. The feature is that it is formed. However,
On the lower side in the figure of the four sides of the semiconductor device, a pair of external electrodes 16 at the center is formed short.

According to the semiconductor device of this embodiment, the arrangement pitch of the external electrodes 16 (leads 13) on each side of the semiconductor device is reduced toward the center, and the width of the external electrodes 16 (leads 13) is toward the center. By making the width narrower, the external electrodes 16 can be provided at the center of each side at a higher density than in the first embodiment. Then, while increasing the density of the semiconductor elements in the semiconductor device, the reliability of the semiconductor device can be improved by the same operation as in the first embodiment. If the leads are lengthened at the corners, there is a risk that the leads at the ends of adjacent sides may come into contact with each other or the suspension leads, but there is no such restriction at the center of the side.

In the present embodiment, it is preferable that the area of the lower surface of the external electrode 16, which is the lower part of the lead 13, be increased toward the corner. The external electrode 16
Generally, it is connected to a connection terminal of a mounting board such as a printed wiring board by soldering. In this case as well, a stress such as a thermal stress applied to a connection portion between the two is larger at a corner of the semiconductor device. Therefore, by increasing the area of the lower surface of the external electrode 16 toward the corner, the reliability of the connection between the external electrode 16 and the connection terminal of the mounting board can be maintained high.

Furthermore, in the present embodiment, the semiconductor device 4
In the lower side of the figure, one pair of external electrodes 16 at the center is shortened, and the shape of the external electrode 16 is changed differently from the other sides. As described above, it is easier to change the shape of one or a plurality of external electrodes on one side to a shape different from the other sides by changing the arrangement pitch of the external electrodes. The external electrode having a shape different from that of the other sides serves as a mark for identifying a position and a direction when the semiconductor device is inspected and mounted on a printed wiring board. As described above, the method used as the identification mark is not limited to the method in which the arrangement pitch of the external electrodes is different between the corners and the center of the side as in the embodiment, and the arrangement of the external electrodes is the same pitch. The effect can be exhibited even if it is the one.

(Third Embodiment) Next, a third embodiment will be described. FIG. 6 is a back view of the semiconductor device according to the present embodiment. Also in this embodiment, the cross-sectional structure of the semiconductor device is the same as the structure of the first embodiment shown in FIG. Also,
Since the top structure of the semiconductor device according to the present embodiment can be easily understood from the rear view shown in FIG. 6, illustration of the top view is omitted.

As shown in FIG. 6, in the semiconductor device of this embodiment, the arrangement pitch of the external electrodes 16 (ie, the leads 13) on each side is small at the center of each side and large at the corners. This is the same as the embodiment. The present embodiment is characterized in that the width of the external electrode 16 is wide at the corners of the semiconductor device, whereas the width of the external electrodes 16 is narrower toward the center. However, the length of each external electrode 16 is common.

According to the semiconductor device of this embodiment, the arrangement pitch of the external electrodes 16 on each side of the semiconductor device is reduced toward the center, and the width of the lead 13 is reduced toward the center. The leads 13, that is, the external electrodes 16 can be provided at the center at a higher density than in the first embodiment. Then, while increasing the density of the semiconductor element in the semiconductor device,
By the same operation as that of the embodiment, the reliability of the semiconductor device can be improved.

In this embodiment, since the area of the lower surface of the external electrode 16 is larger at the corners than at the center of the side, the following operation and effect can be obtained. As described above, in a state where the semiconductor device is mounted on a mounting board such as a printed wiring board, a stress such as a thermal stress applied to a connection portion between the two is larger at a corner of the semiconductor device. Therefore, by increasing the area of the lower surface of the external electrode 16 at the corners rather than at the center of the side, it is possible to increase the bonding force between the external electrodes near the corners and the connection terminals of the mounting board,
The reliability of the connection between the external electrode 16 and the mounting board can be kept high.

In particular, as in the present embodiment, the external electrodes 16
Is larger at the corners than at the center of the side, it is easy to increase the area of the lower surface of the external electrode toward the end of the side. That is, in addition to the effect of improving the reliability of the semiconductor device itself, when the semiconductor device is mounted on a mounting substrate such as a printed wiring board, the reliability of the joint between the external electrode of the semiconductor device and the wiring of the mounting substrate is reduced. Can be improved.

The mounting on the printed wiring board is generally performed by aligning the printed wiring board with the wiring conductor at a center line perpendicular to the semiconductor device. In this method, the surface tension of the solder is balanced. It is known that a self-alignment effect occurs and the position is corrected. Therefore, since the self-alignment effect is increased by increasing the width of the lower surface of the external electrode, there is an advantage that the mounting of the semiconductor device on the mounting substrate becomes easier.

In the present embodiment as well, as shown by the broken line in FIG.
By making the shape different from other external electrodes, it is possible to easily and quickly identify the connection relationship between the external electrodes and the connection terminals on the wiring of the mounting board when mounting the semiconductor device on the mounting board. it can.

(Other Embodiments) Next, other embodiments which can be commonly applied to the above embodiments will be described.

In the above embodiments, the lower surface of the pad 11 may be exposed. In this case, if the suspension lead 10 is formed in a straight shape without providing a step, the lower surface of the die pad 11 is exposed from the sealing resin. With the single-sided sealing type semiconductor device, the thickness of the entire semiconductor device can be further reduced.

As shown in FIGS. 7A and 7B, a wide portion 18 can be provided inside the lead 13 in each of the above embodiments. Here, the two grooves 19 of the lead 13
One groove 19 is in a narrow portion, and the other groove 1
9 is located at the inner wide portion 18. in this way,
By processing the width in the thickness direction such that the width of the lead 13 on the inner side in the sealing resin 15 is wider than the outer width, the adhesive strength between the external electrode and the sealing resin can be enhanced. it can. In particular, the lead 13 can be prevented from coming off or peeling off by the anchor effect of the wide portion 18 against the force for pulling the lead 13 to the side, and the reliability of the semiconductor device can be improved.

Further, in the wide portion 18 of the lead, as shown by the broken line in FIG. 7A, the width of the portion below the lead 13 to be the external electrode 16 is reduced, so that the lead 13 is pulled downward. An anchor effect can be generated for the force, which is effective in preventing the external electrode 16 from being pulled out or peeled off by a force pulling the external electrode 16 downward, thereby improving the reliability of the semiconductor device.

However, such a stepped shape may be provided not only in the wide portion but also in the narrow portion, or the stepped shape may be provided for a flat straight lead having no wide portion. May be.

The groove 1 as shown in FIGS.
The present invention can be applied to a lead having no 9.

In the second and third embodiments, even if the arrangement pitch of the external electrodes 16 is uniform, the area of the lower surface of the external electrode 16 is small at the center of the side and large at the corner. As a result, it is needless to say that there is an effect of improving the reliability of bonding between the external electrode 16 of the semiconductor device and the connection terminal such as a printed wiring board.

In each of the above embodiments, the suspension lead and the die pad are present, but the suspension lead and the die pad are not necessarily required. The effects of the present invention can be effectively exhibited even in a semiconductor device having no suspension lead or die pad.

Further, in each of the above embodiments, a thin metal wire is used as a connecting member for electrically connecting the lead and the electrode pad of the semiconductor chip.
It goes without saying that bumps or the like may be used.

[0094]

According to the first semiconductor device of the present invention, there is provided a resin-sealed semiconductor device in which a semiconductor chip, a lead, and a connecting member are sealed in a sealing resin with the lower surface of the lead exposed. The lower portion of the lead functions as an external electrode, and the arrangement pitch of the external electrode on the back surface of the semiconductor device is smaller at the center of the side than at the corner, so that corners where stresses such as thermal stress act strongly are particularly strong. By preventing defects such as detachment and peeling of leads in the above, reliability can be improved while increasing the density of semiconductor elements in the semiconductor device.

According to the second semiconductor device of the present invention, in a resin-sealed semiconductor device in which a semiconductor chip, a lead, and a connecting member are sealed in a sealing resin with the lower surface of the lead exposed, The lower portion functions as an external electrode, and the area of the lower surface of the external electrode on the back surface of the semiconductor device is larger at the corner than at the center of the side. By increasing the bonding strength with the mounting substrate, the reliability of the semiconductor device after mounting can be improved.

According to the third semiconductor device of the present invention, in a resin-sealed semiconductor device in which a semiconductor chip, a lead, and a connecting member are sealed in a sealing resin with the lower surface of the lead exposed, Since the lower portion functions as an external electrode and the shape of at least one external electrode on one of the sides is formed to be an identification mark of a reference position of the semiconductor device, the semiconductor device is inspected. The reference position at the time of mounting on the mounting board can be easily and quickly identified, and the manufacture of the semiconductor device can be facilitated.

According to the first lead frame of the present invention,
A lead frame for realizing the effects of the first semiconductor device can be provided.

According to the second lead frame of the present invention,
A lead frame for obtaining the operation and effect of the second semiconductor device can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a resin-sealed semiconductor device according to a first embodiment.

FIG. 2 is a top view showing the structure of the resin-encapsulated semiconductor device according to the first embodiment through a sealing resin.

FIG. 3 is a back view of the resin-encapsulated semiconductor device according to the first embodiment.

FIG. 4 is a plan view showing an example of the structure of a lead frame suitable for manufacturing the resin-sealed semiconductor device according to the first embodiment.

FIG. 5 is a rear view of the resin-sealed semiconductor device according to the second embodiment.

FIG. 6 is a back view of a resin-sealed semiconductor device according to a third embodiment.

FIG. 7 is a plan view and a perspective view showing the shape of a lead according to another embodiment.

FIG. 8 is a cross-sectional view of a conventional double-sided sealed semiconductor device.

FIG. 9 is a cross-sectional view of a conventional single-side encapsulated semiconductor device.

FIG. 10 is a back view of a conventional single-sided sealed semiconductor device.

FIG. 11 is a cross-sectional view of a semiconductor device according to a modification of the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Die pad 12 Semiconductor chip 13 Lead 14 Fine metal wire (connection member) 15 Sealing resin 16 External electrode 17 Stepped portion 18 Wide portion 19 Groove 20 Outer frame

Claims (21)

[Claims] 1. A semiconductor chip having an electrode pad on a main surface, a polygonal and plate-shaped sealing resin for sealing a peripheral region including the semiconductor chip, and a semiconductor chip in the sealing resin. A plurality of leads extending from a close position to a side end of the sealing resin and having at least a part of a lower surface exposed from the sealing resin, and a connection for electrically connecting the electrode pads of the semiconductor chip and the leads; Wherein the lower portion of the lead functions as an external electrode, and the arrangement pitch of the external electrodes on the back surface of the semiconductor device is smaller at the center of the side than at the corner of the sealing resin. Resin-encapsulated semiconductor device. 2. The semiconductor device according to claim 1, wherein the length of the lead is longer at a center of the side than at a corner of the sealing resin. 3. The semiconductor device according to claim 1, wherein a width of a lower surface of the external electrode on a back surface of the semiconductor device is wider at a corner than at a center of a side of the sealing resin. Semiconductor device. 4. The semiconductor device according to claim 1, wherein the area of the lower surface of the external electrode on the back surface of the semiconductor device is more corner than at the center of the side of the sealing resin. A resin-encapsulated semiconductor device characterized by being large in a portion. 5. The semiconductor device according to claim 1, wherein a wide portion is provided in a part of the lead on an inner side of a sealing resin. Semiconductor device. 6. The semiconductor device according to claim 1, wherein a lower width of at least a part of the lead is smaller than an upper width. . 7. The semiconductor device according to claim 1, wherein a groove is formed in a part of said lead. 8. The semiconductor device according to claim 1, wherein at least a portion of the lead exposed from the sealing resin is plated with palladium. Semiconductor device. 9. The semiconductor device according to claim 1, wherein at least one external electrode shape on one of the sides of the sealing resin is at a reference position of the semiconductor device. A semiconductor device formed to be an identification mark. 10. A semiconductor chip having an electrode pad on a main surface, a polygonal and plate-shaped sealing resin for sealing a peripheral region including the semiconductor chip, and a semiconductor chip in the sealing resin. A plurality of leads extending from a close position to a side end of the sealing resin and having at least a part of a lower surface exposed from the sealing resin, and a connection for electrically connecting the electrode pads of the semiconductor chip and the leads; A lower portion of the lead functions as an external electrode, and an area of a lower surface of the external electrode on a back surface of the semiconductor device is larger at a corner portion than at a center portion of a side of the sealing resin. A resin-encapsulated semiconductor device. 11. A semiconductor chip having an electrode pad on a main surface, a polygonal and plate-shaped sealing resin for sealing a peripheral region including the semiconductor chip, and a semiconductor chip in the sealing resin. A plurality of leads extending from a close position to a side end of the sealing resin and having at least a part of the lower surface exposed from the sealing resin, and a connection for electrically connecting the electrode pads of the semiconductor chip and the leads; A lower portion of the lead functions as an external electrode, and at least one external electrode on one of the sides of the sealing resin serves as an identification mark of a reference position of the semiconductor device. A semiconductor device characterized by being formed in a semiconductor device. 12. A lead frame for mounting a semiconductor chip having an electrode pad on a main surface, the lead frame extending outward from a position close to a mounting region of the semiconductor chip. And a plurality of leads connected to the outer frame and arranged so that the arrangement pitch is smaller at the center of the side than at the corners of the outer frame. 13. The lead frame according to claim 12, wherein the length of the lead is larger at a center of the side than at a corner of the outer frame. 14. The lead frame according to claim 12, wherein a width of a lower surface of the lead is wider at a corner than at a center of a side of the outer frame. 15. The lead frame according to claim 12, wherein an area of a lower surface of the lead is larger at a corner portion than at a central portion of a side of the outer frame. Resin-molded lead frame. 16. The lead frame according to claim 12, wherein a wide portion is provided on a part of the lead on a side close to the semiconductor chip mounting position. And lead frame. 17. The lead frame according to claim 12, wherein a lower part width of at least a part of the lead is smaller than an upper part width. . 18. The lead frame according to claim 12, wherein a groove is formed in a part of the lead. 19. The lead frame according to claim 12, wherein at least the lead is plated with palladium. 20. A lead frame for mounting a semiconductor chip having an electrode pad on a main surface, comprising: a polygonal outer frame; and an outer frame extending outward from a position close to the semiconductor chip. A plurality of leads connected to each other and formed so that the area of the lower surface is larger at the corners than at the center of the sides of the outer frame. 21. The lead frame according to claim 12, further comprising: a die pad for mounting the semiconductor chip; and a suspension lead for connecting the die pad to the outer frame. A lead frame further provided.