JPS63164254A - semiconductor equipment - Google Patents

Abstract

PURPOSE:To prevent the deterioration in moisture resistance in a resin sealed type package, by forming a tab, which is the pellet mount in such a shape that its planar shape does not have corner parts. CONSTITUTION:In an electronic device 1 having a resin sealed type package 14, the planar shape of a tab 8, on which a pellet 12 is mounted, is formed in a shape without corner parts. For example, the tab 8 is formed in an approximately full-circular flat shape. Corner edges are not provided at the circumference. The group of the tips of inner leads 4 is arranged in a circular ring shape so that the tips are closely located to the circumference of the tab 8. Thus the concentration of stress yielded with thermal stress at the corner parts of the tab can be prevented. Therefore separation of the tab starting at the corner parts can be prevented. As a result, the deterioration in moisture resistance can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technology for preventing moisture resistance deterioration in semiconductor devices, particularly in resin-sealed packages, such as mini square puff cages (hereinafter referred to as MSPIC). The present invention relates to a technique effective for use in a semiconductor integrated circuit device (IC) equipped with a semiconductor integrated circuit device (IC).

[Conventional technology]

As a surface-mount type semiconductor integrated circuit device to achieve high-density mounting, leads are arranged on all sides around a tab to which a pellet is bonded, and the outer lead is bent almost vertically downward. There are MSPICs that have sealed packages.

An example of MSPIG mentioned above is published by Nikkei McGraw-Hill [Separate page Micro Devices No. 2J, June 11, 1980, P148-P159].

[Problem that the invention seeks to solve]

However, in such an MSPIC, silicon forming the pellet, 4270I forming the lead frame, the body, and 4M forming the package.
MSII
When C was subjected to temperature cycle tests, hot hammer tests, etc., 81 peeling occurred at the adhesive interface between the package and lead frame, and moisture entered through cracks starting from the corners on the back of the tab, resulting in As a result, there is a problem that moisture resistance is reduced.

An object of the present invention is to provide a semiconductor device that can prevent deterioration in moisture resistance in a resin-sealed package.

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

[Means for solving problems]

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

That is, the tab, which is the attachment part for the pellet resin-sealed in the package, is formed so that its planar shape does not have a square part.

[Effect]

According to the above-mentioned means, even if the tab expands due to heat caused by a temperature cycle test, etc., the tab does not have a sharp corner, so
The concentration of mechanical stress associated with this is eliminated or suppressed to a small level. In other words, even if stress is generated inside the package due to thermal expansion, the phenomenon of concentration of stress on the portion of the package that is in contact with the outer periphery of the tab can be avoided. As a result, peeling of the package caused by this stress concentration is prevented.

[Embodiment 1] FIG. 1 is a plan view showing an MSI"IC in the process of being manufactured as an embodiment of the present invention, and FIG. 2 is an enlarged partial sectional view thereof.

In this embodiment, the MSPICI includes a lead frame 2, which is configured as shown in FIG. 1 before packaging. That is, the lead frame 2 has a plurality of inner leads 4 arranged in a substantially radial shape so that a substantially perfect circular space 3 remains at the center point, and each inner lead 4 is integrally connected to the inner leads 4. A plurality of outer leads 5 arranged in a cross shape on all sides, a dam 6 constructed between adjacent outer leads 5.5, a substantially square outer frame 7 connected to the group of outer leads 5, A tab 8 is arranged in the empty space 3 and is formed into a substantially perfect circular flat plate shape whose planar shape is slightly smaller than this, and a dam 6 is protruded from two places to suspend the tab 8. It is equipped with a tab hanging lead 9.

The tab 8 is formed into a substantially circular flat plate shape, and has no edged corners on its outer periphery. The lead frame 2 is formed by punching and pressing. Therefore, for example, by forming the blade of a press die for punching out the tab 8 into a perfect circle, the perfect circular tab 8 can be formed at the same time as the punching process. In addition, since the tab 8 is formed in a circular shape, the inner lead 4
The tips of the tab 8 are arranged in a circular ring shape close to the outer periphery of the tab 8.

A pellet 12 on which an integrated circuit is built is bonded onto the tab 8 by appropriate means.
A wire 13 is connected between the electrode pad and each inner lead 4.
are each bonded. The integrated circuit of the pellet 12 is electrically drawn out to the outside via electrode pads, wires 13, inner leads 4, and outer leads 5.

This MSPICI is equipped with a package 14 that is integrally molded into a substantially square flat plate shape using a resin using a transfer molding method.
3 and tab 8 are non-hermetically sealed. That is, the five groups of outer leads other than the tabs 8 and the like protrude from each of the four side surfaces of the package 14, and the five groups of outer leads are bent substantially vertically downward on the outside of the package 14. Incidentally, after the package 14 is molded, the outer frame 7 and the dam 6 between the adjacent outer leads 5.5 are cut off.

Next, the action will be explained.

The MSPIC having the above configuration is subjected to a sampling inspection before being shipped. Environmental tests including temperature cycle tests and thermal 1#1 impact tests will be carried out on New Year's Eve as sampling inspections. When thermal stress occurs during such environmental tests or actual use, the MSPI
C, stress is generated inside the buff cage 14 due to the difference in thermal expansion coefficient of the purchased materials.

By the way, when the planar shape of the tab is a regular square, the corner portions are sharp right angles, so that the internal stress of the package is concentrated near the corner portions of the tab. The inventor of the present invention has revealed that there is a problem in that peeling occurs at the interface between the tab and the package or the tab and the pellet due to repeated stress due to thermal stress caused by aging.

If such peeling occurs in the MSPIC, the moisture resistance will drop sharply because the package is small and thin.

However, in this embodiment, since the tab 8 has a substantially perfect circular planar shape, peeling does not occur between the tab 8 and the package 14 or between the tab 8 and the pellet 12. That is, when the tab 8 thermally expands, since the tab 8 is formed into a perfect circular shape, the elongation of the thermal expansion is dispersed in all directions, so that the concentrated stress is eliminated. As a result, even if repeated stress due to thermal stress acts, the phenomenon of peeling occurring at the interface between the tab and the package or the tab and the pellet can be prevented.

According to the embodiment 1r1, the following effects can be obtained.

(By forming the tab 11 so that its planar shape is approximately a perfect circle, it is possible to prevent the stress generated due to thermal stress from concentrating on the corner of the tab. It is possible to prevent the occurrence of !All separation from the starting point, and as a result, it is possible to prevent a decrease in moisture resistance.

(2) According to the above (1), since the occurrence of peeling can be prevented, it is possible to realize a higher integration density and packaging density of a semiconductor device having a thin and small package.

(3) Since the substantially perfect circular tab can be formed at the same time as the lead frame is punched and pressed during the manufacturing process of the semiconductor device, it is possible to suppress a decrease in work efficiency.

(4) By forming the tab into a substantially perfect circular shape,
Since the tip groups of the inner leads can be arranged in a circular ring shape, the wire bonding lengths can be shortened and made substantially equal to each other, so that bondability can be improved.

[Embodiment 2] FIG. 3 shows a second embodiment of the present invention, and is a plan view corresponding to FIG. 1.

The second embodiment differs from the first embodiment in that the tab 8A is formed into a substantially square shape, and the curved portion 10 is formed at the corner portion with a relatively large curvature. Since there are no edges and stress chains are avoided, the action and effect are substantially the same as in the first embodiment.

Although the invention made by the present inventor has been specifically explained based on Examples, the present invention is not limited to the above Examples (although it is possible to make various changes without departing from the gist of the invention). Needless to say.

For example, the planar shape of the tab is not limited to a perfect circular shape, but may be formed into an elliptical shape.

Further, in order to disperse stress concentrated on the pellet, it is desirable to form a chamfered portion at the end of the pellet.

The above explanation will mainly focus on the field of application of the invention made by the present inventor, which is the resin-sealed MSP.
Although the description has been given of a case where the present invention is applicable to an IC, the present invention is not limited thereto, and can be applied to any other electronic device such as an IC equipped with a resin-sealed puff cage.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By forming the tab, which is the pellet attachment part, so that its planar shape has no corners, stress generated inside the resin-sealed package due to ripening stress is prevented from concentrating on the corners of the tab. Therefore, it is possible to prevent the occurrence of a peeling phenomenon starting from the corner portion.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an MSPIC in the process of manufacturing which is an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view thereof, and FIG. 3 is a plan view corresponding to FIG. 1 showing Embodiment 2. It is. ■...MSI"'IC (semiconductor device), 2... Lead frame, 3... Blank space, 4... Inner lead, 5
...Outer lead, 6...Dam, 7...Outer frame, 8
．． 8A...Tab, 9...Tab hanging lead, 10...
- Curved portion, 12... Pellet, I3... Bonding wire, 14... Package.

Claims (1)

[Scope of Claims] 1. A semiconductor device that is an electronic device equipped with a resin-sealed package, characterized in that a tab on which a pellet is mounted has a non-square planar shape. 2. The semiconductor device according to claim 1, wherein the tab has a circular planar shape. 3. The semiconductor device according to claim 1, wherein the tab has a curved portion formed at a corner thereof.