JPH07193180A - Resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device whose package is adaptable for various chip sizes, holds leads firmly and withstands heat cycles. CONSTITUTION:A semiconductor device comprises a semiconductor chip 4; an island 3 smaller than the chip, on which the chip is mounted; leads 1 connected with electrodes 6 of the chip through electric conductors; and a plastic package 2. The leads are bent in the package: their outer ends of the leads are in a first horizontal plane that is half the height of the plastic package, while their inner ends are in a second horizontal plane at a lower level in the package. The island is at a level higher than the second plane. The conductors from the chip can be connected with the leads in either the first plane or the second plane depending on the size of the chip. The package has the same length above and below the electrodes of the chip.

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, and more particularly to a resin-sealed semiconductor device having a lead frame structure applicable to various sizes of semiconductor chips.

[0002]

2. Description of the Related Art In recent years, a semiconductor device (or package) in which a semiconductor element is mounted on a lead frame, connected by wire bonding, and then resin-sealed by transfer molding
Is widely used. In this package, the number of leads and the package size are standardized, and when a new semiconductor element is developed, it is general to select the most suitable size from the standardized packages.

However, there are the number of leads and the chip size as the selection factors of the package, and when the number of leads is the same and the chip size is larger than the standard, a new lead frame must be designed. Conversely, if the chip size is considerably smaller than the standard even with the same number of leads, a small semiconductor chip will be mounted on a large island.
When such a selection is made, the length of wire bonding becomes long, which may cause problems such as island touch of the bonding wire or deformation of the leads during transfer molding and short-circuiting between the leads.

In order to prevent this, it is sufficient to raise a dedicated lead frame according to the chip size, but it takes a great deal of cost and time to design and manufacture a die, and the type of lead frame increases, so that management is also required. It had the drawback of becoming complicated.

Therefore, as shown in the cross-sectional view of FIG. 4, a patent application has been filed in which an island is projected above a lead and a semiconductor element having an outer diameter larger than that of the island is mounted on the island (Japanese Patent Laid-Open No. Hei. 218274). That is, in FIG. 4, 11 is a lead, which extends into the resin sealing body 12. Reference numeral 13 denotes an island held above the tip of the lead 11, to which a semiconductor element 14 having a larger outer diameter is connected by a conductive mounting material 15 such as Ag paste. Although the outer periphery of the semiconductor element 14 protrudes from the island 13 and covers the tip portion of the lead 11,
Is located above the tip of the lead 11, the semiconductor element 14 and the lead 11 never come into contact with each other. The electrode 16 of the semiconductor element 14 and the lead 11 are connected by a bonding wire 17.

Therefore, according to this application, semiconductor elements of various chip sizes can be mounted on a common lead frame. However, in this configuration, the resin sealing thickness 18 on the electrode surface of the semiconductor element is equal to the resin sealing thickness 1 below the island.
Since it is smaller than 9, the occurrence of stress becomes uneven in the upper and lower parts of the package when a heat cycle or the like is applied, and cracks may occur in the package.

In order to avoid this problem, it is conceivable to lower the island 13 downward, but the lead-out position of the lead 11 from the resin sealing body 12 is also lowered, and the holding force of the lead 11 by the resin sealing body 12 is reduced. drop down. Therefore, a resin crack may occur at the lead-out portion of the lead 11.

[0008]

As described above, in the resin-encapsulated semiconductor device, in the case of a large semiconductor element that cannot be mounted on the standard lead frame, it is necessary to newly design the lead frame. When a semiconductor element smaller than the standard is mounted on the lead frame, a bonding wire short-circuit occurs, and in order to avoid this problem, there is a problem that a dedicated lead frame must be raised according to the chip size and the number of leads. It was In order to solve this problem, a method of projecting a small island above the lead surface and mounting a semiconductor element larger than the outer diameter of this island was also considered, but it is vulnerable to thermal cycling and cracks occur in the package. There was a problem.

The present invention has been made in view of the above circumstances and provides a resin-encapsulated semiconductor device capable of mounting semiconductor elements of various chip sizes, resistant to cooling / heating cycles, and high in holding strength of a lead resin. It is what

[0010]

In order to achieve the above object, according to the present invention, a semiconductor element, an island having an outer diameter smaller than that of the semiconductor element and mounting the semiconductor element, an electrode portion of the semiconductor element, and an electrical component In a resin-sealed semiconductor device in which a plurality of leads connected by a static connection member are resin-sealed, and the leads are held in a first plane located substantially in the center in the thickness direction of the resin-sealed body. One end of the island is bent and molded into a second surface having a step below the first surface in the resin sealing, and the island is formed into the second surface.
It is characterized in that it is located above the plane.

In addition, the connection point of the lead with the electrical connection member can be appropriately selected on the first surface or the second surface according to the size of the semiconductor element. Further, the resin sealing thickness on the semiconductor element electrode surface and the resin sealing thickness under the island are substantially equal.

[0012]

As described above, according to the present invention, the first inside the resin-sealed body is used.
Since the tip of the lead introduced into the surface of the is bent and formed in the second surface having a step downward, and the island is arranged above the second surface, the semiconductor element larger than the island is formed. Even if is mounted on this island, the semiconductor element and the lead can be in a non-contact state.

In addition, when the size of the semiconductor element becomes larger as it approaches the portion of the first surface of the lead, the connecting point on the lead side of the bonding wire (electrical connecting member) is set to the first point.
The length of the bonding wire can be properly maintained by placing the bonding wire on the surface. When the outer diameter of the semiconductor element is not much larger than the outer diameter of the island, the length of the bonding wire can be made appropriate by placing the connecting point on the lead side of the bonding wire on the second surface. It is possible to prevent lead flow and lead short-circuit during transfer molding.

Further, if the island positions are set so that the resin sealing thickness on the electrode surface of the semiconductor element and the resin sealing thickness under the island are substantially equal, the stress generation during the cooling / heating cycle is even above and below the package. As a result, package cracks and the like can be prevented.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a resin-sealed semiconductor device (surface mount type) according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of an essential part of the first embodiment of the present invention ( A-A in FIG.
Equivalent to the cross-sectional view of the line). 1 and 2, the same parts are designated by the same reference numerals.

In FIG. 2, reference numeral 1 is a lead made of Fe-Ni alloy, Cu or the like, which is introduced into the first surface of the resin encapsulation body 2 made of epoxy resin or the like, which is located substantially in the center in the thickness direction, and inside thereof. The tip of is bent and shaped so that it has a step on the lower side.
Extends in the plane. Reference numeral 3 denotes an island held above the tip of the lead 1. A semiconductor element 4 having an outer diameter larger than this is connected to the island 3 by a conductive mounting material 5 such as Ag paste. The semiconductor element 4
The outer periphery of the lead 1 protrudes from the island 3 and covers the tip of the lead 1.
Since the semiconductor element 4 and the lead 1 are located above the tip of the semiconductor element 4, they do not come into contact with each other.

Next, the electrode 6 of the semiconductor element 4 and the lead 1
Are connected via a bonding wire 7 by means of ultrasonic bonding or the like, and the connection point on the lead 1 is located on the first surface so that the bonding wire has an appropriate length.

Further, the resin sealing thickness 8 on the electrode surface of the semiconductor element 4 and the resin sealing thickness 9 below the island 3 are made substantially equal. Therefore, even when a thermal stress such as a cold heat cycle is applied, the stress on the upper and lower sides of the package can be equalized and a package crack or the like can be prevented. Further, since the lead 1 is led out to the outside from almost the center of the resin sealing body 2 in the thickness direction, a sufficient holding force of the lead 1 by the resin sealing body 2 can be obtained.

Although illustration of the portion of the lead 1 outside the resin encapsulant 2 is omitted, it may be either an insertion type in which the external lead is formed into an inverted L-shape or a surface mount type in which it is formed into a Z-shape. Can also be applied.

Specifically, a package having a thickness of 1.0 mm can be realized as follows. That is, the resin sealing thickness 7 on the electrode surface of the semiconductor element 4 is 0.235 mm, and the thickness of the semiconductor element 4 is 0.
35 mm, the thickness of Ag paste for bonding the semiconductor element 4 is 0.
03mm, thickness of island 3 is 0.15mm, island 3
The lower resin sealing thickness 8 is 0.235 mm. The step between the surface of the island 3 and the second surface of the tip of the lead 1 is 0.05 mm
Just take a degree. Regarding the lateral dimension of the cross-sectional view of FIG. 2, the side length of the island 3 is 4.0 mm, the gap between the island 3 and the tip of the lead 1 is 1.0 mm, and the flat portion of the second surface of the lead 1 is 3.0 mm. Then, the side length of the semiconductor element 4 can be applied up to 10.0 mm at the maximum.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view of a main part similar to FIG. 2, and the same parts as those in FIG. 2 are denoted by the same reference numerals. The basic configuration is the same as that of FIG. 2, but the size of the semiconductor element 4 is slightly larger than the size of the island.

In such a case, if the connection point of the bonding wire to the lead 1 is set to the first surface, the length of the bonding wire 7 becomes too long, causing wire flow at the time of transfer molding, resulting in short circuit between wires. Occurs. Therefore, in this embodiment, the bonding wire 7 is connected to the lead 1 on the second surface so that the bonding wire 7 has an appropriate length.

Further, in this embodiment as well, the resin sealing thickness 8 on the electrode surface of the semiconductor element 4 and the resin sealing thickness 9 below the island 3 are made substantially equal. Therefore, even when a thermal stress such as a cold heat cycle is applied, the stress on the upper and lower sides of the package can be equalized and a package crack or the like can be prevented. Further, since the lead 1 is led out to the outside from almost the center of the resin molded body 2 in the thickness direction, a sufficient holding force for the lead 1 by the resin molded body 2 can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. For example, in the present embodiment, the DIP (Dual Inline Packag) in which the leads are bidirectional
e) The QFP (Qu
It goes without saying that it can also be applied to ad Flat Package). Although an example of the bonding wire is shown as the electrical connection member, a TAB (Tape Automated Bonding) method can also be applied.

[0025]

As described above, according to the present invention, the tips of the leads introduced into the first surface located substantially in the center in the thickness direction of the resin encapsulant are in the second surface having a step below. Since it is bent and formed, and the island is arranged above the second surface, a semiconductor element larger than the island can be mounted on this island, and the lead frame can be shared.

In addition, the length of the bonding wire can be appropriately maintained by appropriately switching the connection point on the lead side of the bonding wire to the first surface or the second surface depending on the size of the semiconductor element. Therefore, the yield and reliability can be improved.

Further, since the position of the island is set so that the resin sealing thickness on the electrode surface of the semiconductor element and the resin sealing thickness under the island are substantially equal to each other, stress is generated during the heat / cool cycle of the package. The upper and lower sides are equalized, and package cracks and the like can be prevented.

Further, since the lead is led out of the resin molded body from substantially the center in the thickness direction of the resin molded body,
It is possible to obtain a highly reliable resin-encapsulated semiconductor device in which the lead-holding force of the resin molded body is sufficiently obtained, cracking from the lead portion and moisture resistance deterioration are prevented.

[Brief description of drawings]

FIG. 1 is a perspective view of a resin type semiconductor device according to an embodiment of the invention.

FIG. 2 is a cross-sectional view of a main part of a resin-sealed semiconductor device according to a first embodiment of the present invention, which corresponds to the cross-sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view of a main part of a resin-sealed semiconductor device according to a second embodiment of the present invention, which corresponds to the cross-sectional view taken along the line AA of FIG.

FIG. 4 is a cross-sectional view of a main part of a resin-sealed semiconductor device according to a conventional technique.

[Explanation of symbols]

 1 ... Lead 2 ... Resin sealing body 3 ... Island 4 ... Semiconductor element 5 ... Conductive mount material 6 ... Electrode 7 ... Bonding wire (electrical connection member) 8 ... Resin thickness on electrode surface 9 ... Resin thickness under island

Claims (4)

[Claims] 1. A semiconductor element, a semiconductor element, an island having an outer diameter smaller than that of the semiconductor element, on which the semiconductor element is mounted, and a plurality of leads connected to an electrode portion of the semiconductor element by an electrical connection member with resin. In the resin-encapsulated semiconductor device as described above, the lead is held in a first surface located substantially in the center of the resin-encapsulated body in the thickness direction, and one end of the lead is in the resin-encapsulated body. Is bent and formed in a second surface having a step below the surface, and the island is located above the second surface. 2. The resin-encapsulated semiconductor device according to claim 1, wherein a connection point of the lead with the electrical connection member is on the first surface. 3. The resin-sealed semiconductor device according to claim 1, wherein the connection point of the lead with the electrical connection member is on the second surface. 4. The resin-encapsulated semiconductor device according to claim 1, wherein the resin encapsulation thickness on the semiconductor element electrode surface and the resin encapsulation thickness under the island are substantially equal to each other.