JP2000058739A - Semiconductor device and lead frame used for manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a semiconductor device capable of suppressing occurrence of package cracks during mounting and achieving uniform and stable ground potential. A package, a metal tab provided in the package and set to a ground potential, a plurality of tab suspension leads formed integrally with the tab and supporting the tab, and fixed to the tab. A semiconductor device comprising: a semiconductor element, a plurality of metal leads extending inside and outside the package, and a conductive wire connecting an electrode of the semiconductor element and the lead portion in the package. A metal ground bar, one end or both ends of which are supported by the tab suspension lead, and which extends to the outer peripheral area of the semiconductor element; and a conductive wire connecting the ground electrode of the semiconductor element and the ground bar. . The tab has an area smaller than an area of the semiconductor element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a resin-sealed semiconductor device and a lead frame used for manufacturing the same.

[0002]

2. Description of the Related Art As one of semiconductor devices (semiconductor integrated circuit devices), a metal lead frame is used, and a semiconductor chip fixed to a tab of the lead frame, an inner end portion of the lead, electrodes and leads of the semiconductor chip are connected. 2. Description of the Related Art A resin-sealed semiconductor device in which a conductive wire or the like to be connected is sealed with an insulating resin is known.

[0003] In mounting this resin-encapsulated semiconductor device, when re-heating (reflowing) the solder previously attached to the mounting end of the outer end of the lead or the land of the mounting board to fix the lead to the land, a solder reflow soldering is required. Package cracks and wire breakage may occur due to expansion force (steam explosion) caused by vaporization of moisture between the resin and the tabs forming the package due to the heat of the time.

[0004] For example, "Electronic Materials" 1
Issued April 1988, April 1, 1988, P74-P
79, in a high-density surface-mounted semiconductor device,
It describes resin peeling and resin cracking caused by moisture absorption and reflow mounting of the resin forming the package.

Japanese Patent Application Laid-Open No. 63-204753 discloses a semiconductor device in which a die pad (tab) is smaller than a semiconductor element (semiconductor chip) in order to suppress the occurrence of the resin crack. .

On the other hand, by connecting a plurality of power supply electrodes (ground electrodes) of the semiconductor chip to tabs that are set to the ground potential by wires, the ground potential is made uniform and stable (ground reinforcement), and the semiconductor device is strengthened. There are known techniques for promoting a stable operation of a vehicle. For such technologies,
For example, it is described in Japanese Patent Application No. 6-103737.
Japanese Patent Application Laid-Open No. 64-37032 describes a two-layer lead frame assembly.

[0007]

SUMMARY OF THE INVENTION For stable operation of a semiconductor device, a ground electrode (power supply electrode) of a semiconductor chip is required.
The structure that connects the tab that becomes the ground potential with a wire
In a structure in which a tab is made smaller than a semiconductor chip in order to prevent a package crack at the time of solder reflow of a semiconductor device, since the tab does not protrude outside the semiconductor chip, a wire cannot be connected and cannot be adopted.

That is, even when the tab is small, the bonding is performed such that the center of the semiconductor chip is aligned with the center of the tab during chip bonding. Therefore, when the semiconductor chip is fixed to the tab, the tab is completely formed. In other words, it is hidden under the semiconductor chip, and there is no portion for connecting wires.

On the other hand, the tab is supported by a tab suspension lead, and the tab suspension lead is formed integrally with the tab. Therefore, it is conceivable to connect a wire to the tab suspension lead portion.

However, the tab suspension leads are generally provided at the four corners or two opposing sides of the rectangular tab, and the position is limited. Further, one end of the wire connected to the ground electrode cannot always be connected to the nearby tab suspension lead due to the arrangement of the electrodes of the semiconductor chip and the direction of the wire tension.

An object of the present invention is to provide a semiconductor device capable of suppressing occurrence of package cracks during mounting and achieving uniform and stable ground potential, and a lead frame used for manufacturing the same.

[0012] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0013]

The following is a brief description of an outline of typical inventions disclosed in the present application.

(1) A package, a metal tab provided in the package and set to a ground potential, a plurality of tab suspension leads formed integrally with the tab and supporting the tab, A semiconductor device having a fixed semiconductor element, a plurality of metal leads extending inside and outside the package, and a conductive wire connecting an electrode of the semiconductor element and the lead portion in the package. A metal ground bar, one end or both ends of which are supported by the tab suspension leads and extend to the outer peripheral area of the semiconductor element; and a conductive wire connecting the ground electrode of the semiconductor element and the ground bar. Having. The tab has an area smaller than an area of the semiconductor element.

Such a semiconductor device is manufactured using a lead frame having the following configuration.

A tab, which is entirely made of a metal-patterned plate, and to which the semiconductor element is fixed, a plurality of tab suspension leads for supporting the tab, and a plurality of leads for facing the tab toward the tab. A lead frame having a configuration in which the tab has an area smaller than the area of the semiconductor element, and a tip of the lead is connected to a conductive wire connected to an electrode of the semiconductor element, One end or both ends are supported by the tab suspension lead, and the ground bar extends to the outer peripheral region of the semiconductor element fixed to the tab, and is connected to a wire connected to a ground electrode of the semiconductor element. Have.

(2) In the configuration of the means (1), the ground bar has a bent portion at least in part. In manufacturing the semiconductor device having this configuration, in the lead frame used in the means (1), the ground bar has a structure having a bent portion at least in part.

According to the means (1), since the tab (a) has a smaller area than the area of the semiconductor element, the area of contact with the semiconductor element is reduced, and water vapor generated by heat or the like during mounting of the semiconductor device. Explosion is less likely to occur, and the occurrence of package cracks can be prevented.

(B) Therefore, the yield at the time of mounting on a mounting board is improved, and the reliability of the mounted semiconductor device is increased.

(C) A ground bar extends in the outer peripheral area of the semiconductor element, and the ground bar is connected to the other end of the wire, one end of which is connected to the ground electrode of the semiconductor element. Of the semiconductor device can be achieved, and stable operation of the semiconductor device can be achieved. Therefore, the reliability of an electronic device incorporating the present semiconductor device is improved.

(D) Since the ground bar extending from the tab suspension lead extends into the resin forming the package, the contact area between the resin and the metal portion increases, and the bonding strength between the two increases. Thus, the effect of suppressing package cracks during solder reflow can be obtained.

(E) The use of a lead frame having a tab having a smaller area than the area of the semiconductor element and having a ground bar extending in the outer peripheral area of the semiconductor element for manufacturing the semiconductor device, Semiconductor devices that can prevent damage caused by heat, such as package cracks, can be manufactured, and wires connected to the ground electrode can be connected to the ground bar to achieve uniform and stable ground potential of the semiconductor device. A semiconductor device that can be manufactured can be manufactured.

According to the means (2), in addition to the effect of the structure of the means (1), since the ground bar is bent, the contact area between the ground bar and the resin forming the package is further increased. Thus, the effect of suppressing package cracks during solder reflow is further enhanced.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIGS. 1 to 7 relate to a semiconductor device according to an embodiment (Embodiment 1) of the present invention.

The resin-sealed semiconductor device 1 of the first embodiment
As shown in FIG. 1 and FIG. 2, a rectangular package (sealing body) 2 made of an insulating resin
And a plurality of leads 3 projecting from four sides of the package 2. The leads 3 extend inside and outside the package 2. The lead portion (outer lead) projecting from the package 2 is a gull-wing type having a surface mounting shape.

In the center of the package 2,
A semiconductor element (semiconductor chip) 4 is located. The semiconductor chip 4 is fixed to a tab 5 located in the package 2 via a conductive bonding material 6.

In the present invention, package cracks and the like are prevented from occurring due to heat at the time of mounting the semiconductor device.
The semiconductor chip is supported by a tab having a smaller area than the area of the semiconductor chip.

According to the present invention, tabs having an area smaller than the area of the semiconductor chip are not shown, but (1) circular, oval or polygonal tabs smaller than the semiconductor chip;
(2) a tab having a bar shape or a bent bar shape having a length longer than that of the semiconductor chip, (3) a tab having a shape obtained by combining the above (1) and (2), and (4) a combination of a plurality of bar pieces. The tab is a trifurcated or cross-shaped tab, or a tab formed by combining the above (1).

In the first embodiment, as shown in FIGS. 1 and 3, the tab 5 is a cross-shaped tab 5 that supports a diagonal portion of the semiconductor chip 4. In this cross tab 5, the center of the cross of the cross is the center of the tab 5.

A tab suspension lead 7 is formed on each piece of the cross-shaped tab 5. The tab suspension lead 7 extends inside the package 2 and is cut at the edge of the package 2.

A structure may be used in which at least a part of the tab suspension lead 7 is bent in the middle, extends in parallel with the leads 3 arranged in parallel and protrudes outside the package 2, and is used as a ground lead.

On the other hand, a ground bar 10 extending parallel to each side is provided outside each side of the semiconductor chip 4. Both ends of the ground bar 10 are connected to adjacent tab suspension leads 7, respectively. This ground bar 10 also extends inside the package 2.

The tab 5, tab suspension lead 7, ground bar 10, and lead 3 are formed of a metal such as a copper alloy or an iron-nickel alloy plate.

On the other hand, the electrodes of the semiconductor chip 4 and the tips of the leads 3 located in the package 2 are connected by conductive wires 11.

The ground electrode and the ground bar 10 of the electrodes of the semiconductor chip 4 are connected to the conductive wires 11.
Connected by These wires 11 are also located in the package 2.

In the first embodiment, the electrodes of the semiconductor chip 4 are provided along the entire periphery of the semiconductor chip 4, but the ground electrodes are arranged at substantially equal intervals. Thereby, the ground potential of each part of the ground wiring of the circuit incorporated in the semiconductor chip 4 can be made uniform, and the semiconductor device 1 operates stably.

In the first embodiment, the tab suspension leads 7
Does not project out of the package 2, but the ground bar 10, the tab suspension lead 7 and the tab 5 are connected to the wire 11.
In addition, the ground potential is maintained via the semiconductor chip 4. Although not shown, some of the leads 3 are ground leads.

Next, a method for manufacturing such a semiconductor device 1 will be described with reference to FIGS.

First, a lead frame 25 as shown in FIG. 3 is prepared. This lead frame 25 has a
It is formed by etching or patterning a metal plate made of a Fe—Ni-based alloy or a Cu alloy with a thickness of 1 mm to 0.15 mm by a precision press.

The lead frame 25 has a shape in which a plurality of unit lead patterns are arranged in series in one direction. FIG.
Shows a unit lead pattern.

The unit lead pattern is formed by a pair of outer frames 26 extending in parallel and a pair of inner frames 27 connecting the pair of outer frames 26 and extending in a direction perpendicular to the outer frames 26. It is formed in a frame 28.

From the inside of the outer frame 26 and the inner frame 27, thin leads 3 protrude parallel to each other at regular intervals (pitch). In addition, the lead portion outside the parallel area of the lead 3 is connected to a thin dam 29 which is parallel to each of the outer frame 26 and the inner frame 27 and arranged in a rectangular frame shape as a whole. The dam 29 functions as a dam for preventing the melted resin from flowing out and as a strength member at the time of resin molding at the time of manufacturing a semiconductor device.

The lead 3 extends to the center of the frame 28 beyond the dam 29. The tip (inner end) of each lead 3
Each is bent so as to converge on a certain substantially rectangular area at the center of the frame 28.

Further, in the rectangular frame formed by the dam 29, a cross-shaped member 30 for connecting the corners of the rectangular frame is provided. This cross-shaped member 30 is, for example, 0.1
It is constituted by an intersection pattern of rods 31 having a width of about 0.2 mm.

A ground bar 10 is provided between adjacent rods 31 in a portion located in the substantially rectangular area. The ground bar 10 extends in parallel with each of the outer frame 26 and the inner frame 27. In FIG. 3, what is indicated by a two-dot chain line is the semiconductor chip 4 fixed to the central portion of the cross-shaped member 30. The ground bar 10 is located in the outer peripheral area of the semiconductor chip 4 and has a rectangular semiconductor shape. The chip 4 extends parallel to each side.

In the cross member 30, the portion to which the semiconductor chip 4 is fixed forms the cross tab 5, and the portion connected to the cross tab 5 forms the tab suspension lead 7.

In one corner of the frame 28, the dam 29 is connected to the flat portion 32. The flat portion 32 is a portion where a runner and a gate through which molten resin flows when the package 2 is formed by transfer molding are arranged.

The outer frame 26 has guide holes 33, 3
4 are provided. The guide holes 33 and 34 are used as guides for transferring and positioning the lead frame 25.

Next, chip bonding is performed on such a lead frame 25 as shown in FIGS. That is, the semiconductor chip 4 is fixed (chip-bonded) to the main surface of the cross-shaped tab 5 of the lead frame 25 by the conductive bonding material 6 as shown in FIG.

Next, as shown in FIGS. 5 and 6, wire bonding is performed. That is, the electrodes of the semiconductor chip 4 (portions indicated by squares along the edge of the semiconductor chip 4 in FIG. 5) and the inner ends of the leads 3 are connected (wire-bonded) by the conductive wires 11.

At this time, some of the electrodes of the semiconductor chip 4 are connected to the ground bar 10 by wires 11. The electrode connected to the ground bar 10 via the wire 11 is a ground electrode. A part of the electrode connected to the lead 3 is also a ground electrode (not shown), and a part of the lead 3 is a ground lead.

In the first embodiment, the electrodes of the semiconductor chip 4 are provided along the entire periphery of the semiconductor chip 4, but the ground electrodes are arranged at substantially equal intervals. As a result, the ground potential of each part of the ground wiring of the circuit incorporated in the semiconductor chip 4 can be made uniform.

Next, the lead frame 25 is sealed in a rectangular area inside the dam 29 with a package 2 made of an insulating resin by a conventional molding (transfer molding) apparatus, and unnecessary lead frame portions are cut. By removing and forming the leads 3 projecting from the package 2, the semiconductor device 1 as shown in FIGS. 1 and 2 is manufactured.

FIG. 7 is a sectional view of the semiconductor device 1 according to the first embodiment mounted on a mounting board 40. In mounting the semiconductor device 1, after accurately positioning the mounting end 35 of the tip of the lead 3 protruding from the package 2 of the semiconductor device 1 on the land 41 of the mounting board 40, the solder is reflowed and soldered. 42, the mounting end 35 is connected to the land 41.
Mechanically and electrically.

The mounting end 3 of the land 41 and the lead 3
5 is provided with a solder layer in advance, is melted by solder reflow, and the mounting end 35 and the land 41 are joined.

In this mounting, the semiconductor device 1 is exposed to a temperature at which the solder melts. And the semiconductor device 1
In the above, the moisture inside the package is rapidly gasified (steam) by the heat at the time of solder reflow, but since the contact area between the tab 5 and the semiconductor chip 4 is small, the steam explosion due to the contained moisture does not occur, and the package Breakage defects such as generation of cracks and wire breakage do not occur.

According to the first embodiment, the following effects can be obtained.

(1) Since the area of the tab 5 is smaller than the area of the semiconductor chip 4, the contact area with the semiconductor chip 4 is reduced, and steam explosion due to heat or the like at the time of mounting the semiconductor device 1 is less likely to occur. Cracks can be prevented from occurring.

(2) From the above (1), the yield when mounting the semiconductor device 1 on the mounting board 40 is improved, and
The reliability of the mounted semiconductor device 1 is improved.

(3) A ground bar 10 extends in an outer peripheral area of the semiconductor chip 4, and a wire 11 having one end connected to a ground electrode of the semiconductor chip 4 is connected to the ground bar 10.
Are connected, the uniformity and stabilization of the ground potential can be achieved, and the stable operation of the semiconductor device 1 can be achieved.

(4) Due to the above (3), the reliability of the electronic device incorporating the semiconductor device 1 of the first embodiment is improved.

(5) Since the ground bar 10 extending from the tab suspension lead 7 extends into the resin forming the package 2, the resin and the metal portion (tab 5, tab suspension lead 7, ground bar 10 and Since the contact area with the lead 3) is increased and the bonding strength between the two is increased, the effect of suppressing package cracking during solder reflow can be obtained.

(6) Use of the lead frame 25 having the tab 5 having a smaller area than the area of the semiconductor chip 4 and having the ground bar 10 extending in the outer peripheral area of the semiconductor chip 4 for manufacturing the semiconductor device 1 Accordingly, it is possible to manufacture the semiconductor device 1 that can prevent damage due to heat such as a package crack when mounting the semiconductor device 1 and to connect the wire 11 connected to the ground electrode to the ground bar 10. It is possible to manufacture the semiconductor device 1 capable of achieving uniform and stable ground potential of the semiconductor device 1.

(Embodiment 2) FIG. 8 is a schematic plan view of a part of a semiconductor device according to another embodiment (Embodiment 2) of the present invention.

The semiconductor device 1 of the second embodiment is different from the semiconductor device 1 of the first embodiment in that the ground bar 10
Has a bent portion 50 at least in part.

Therefore, although not shown, the lead frame 25 also has a structure in which the bent portion 50 is provided at the ground bar 10 portion.

In the semiconductor device 1 of the second embodiment,
In addition to the effects of the semiconductor device 1 of the first embodiment,
Since the ground bar 10 is bent, the contact area between the ground bar 10 and the resin forming the package 2 is further increased, and the effect of suppressing package cracks during solder reflow is further enhanced.

Although the bent portion has a U-shape, it may have a simple projection shape or another shape.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say.

In the above description, the case where the invention made by the present inventor is mainly applied to the manufacturing technique of the surface-mounted resin-sealed semiconductor device, which is the field of application as the background, has been described. Not something. The present invention can be applied to at least the technology for manufacturing a resin-sealed semiconductor device.

[0072]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) Since the area of the tab is smaller than the area of the semiconductor element, the contact area between the tab and the semiconductor element is reduced, so that steam explosion due to heat or the like at the time of mounting the semiconductor device is less likely to occur. Generation can be prevented. Therefore, the yield at the time of mounting the semiconductor device on the mounting board is improved, and the manufacturing cost of the electronic device can be reduced. Further, the reliability of the mounted semiconductor device is increased, and the reliability of the electronic device is improved.

(2) A ground bar extends in the outer peripheral region of the semiconductor element, and the ground bar is connected to the other end of the wire, one end of which is connected to the ground electrode of the semiconductor element. Of the semiconductor device can be achieved, and stable operation of the semiconductor device can be achieved. Therefore, the reliability of an electronic device incorporating the present semiconductor device is improved.

(3) The use of a lead frame having tabs having an area smaller than the area of the semiconductor element and having a ground bar extending in the outer peripheral region of the semiconductor element for manufacturing the semiconductor device, Semiconductor devices that can prevent damage caused by heat, such as package cracks, can be manufactured, and wires connected to the ground electrode can be connected to the ground bar to achieve uniform and stable ground potential of the semiconductor device. A semiconductor device that can be manufactured can be manufactured.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor device according to an embodiment (Embodiment 1) of the present invention, with a portion cut away.

FIG. 2 is a cross-sectional view of the semiconductor device according to the first embodiment.

FIG. 3 is a plan view of a lead frame used for manufacturing the semiconductor device of the first embodiment.

FIG. 4 is a sectional view of the lead frame.

FIG. 5 is a plan view of the lead frame after chip bonding and wire bonding have been completed in the manufacture of the semiconductor device according to the first embodiment;

FIG. 6 is a cross-sectional view of the lead frame in which chip bonding and wire bonding have been completed in the manufacture of the semiconductor device of the first embodiment.

FIG. 7 is a cross-sectional view illustrating a mounting structure of the semiconductor device according to the first embodiment.

FIG. 8 is a schematic plan view of a part of a semiconductor device according to another embodiment (Embodiment 2) of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Package, 3 ... Lead, 4 ... Semiconductor element (semiconductor chip), 5 ... Tab (cross-shaped tab), 6 ... Bonding material, 7 ... Tab suspension lead, 10 ... Ground bar, 11 ... Wire, 25 ... Lead frame, 26 ...
Outer frame, 27 ... inner frame, 28 ... frame, 29 ... dam, 30 ... cross-shaped member, 31 ... rod-shaped body, 32 ... flat portion, 33, 34 ...
Guide holes, 35 mounting ends, 40 mounting boards, 41 lands, 42 solders, 50 bending parts.

Continuing on the front page (72) Inventor Fujio Ito 5-2-21-1 Kamimizu Honcho, Kodaira-shi, Tokyo Inside Hitachi Super-LSI Systems Co., Ltd. (72) Inventor Hiromichi Suzuki Above Kodaira-shi, Tokyo 5-20-1, Mizumotocho F-term (reference), Semiconductor Division, Hitachi, Ltd. 5F067 AA07 AB03 BD05 BD10 BE05 BE07 CD03 DF16 DF17 EA02 EA04

Claims (5)

[Claims] 1. A package, a metal tab provided in the package and set to a ground potential, a plurality of tab suspension leads integrally formed with the tab and supporting the tab, and fixed to the tab. And a plurality of metal leads extending inside and outside the package, and a conductive wire for connecting an electrode of the semiconductor element to the lead portion in the package. A metal ground bar, one end or both ends of which are supported by the tab suspension lead, and which extends to the outer peripheral area of the semiconductor element; and a conductive wire connecting the ground electrode of the semiconductor element and the ground bar. A semiconductor device comprising: 2. The semiconductor device according to claim 1, wherein the tab has an area smaller than an area of the semiconductor element. 3. The semiconductor device according to claim 1, wherein the ground bar has a bent portion at least in part. 4. A tab formed entirely of a metal-patterned plate, to which a semiconductor element is fixed, a plurality of tab suspension leads for supporting the tab, and a plurality of tabs whose front ends face the tab. A lead frame, wherein the tab has an area smaller than an area of the semiconductor element, and a conductive wire connected to an electrode of the semiconductor element is connected to a tip of the lead. A ground that is supported at one end or both ends by the tab suspension lead, extends to an outer peripheral region of the semiconductor element fixed to the tab, and is connected to a wire connected to a ground electrode of the semiconductor element. A lead frame having a bar. 5. The lead frame according to claim 4, wherein the ground bar has a bent portion at least in part.