JPS6255952A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a semiconductor device from being improperly mounted by providing a crystalline tissue different from a bulk near a contact when connecting a terminal led out of sealing resin with a foillike terminal. CONSTITUTION:A burr 2 remains by pressing on an outer terminal 3. The terminal 3 is placed under a bearer 1, a punch 4 is elevationally moved upward and downward to collapse the burr 2. As a result, the portion of tissue different from that of a bulk remains on the end of the terminal 3, or the burr 2 is separated from the root to possibly cause a small recess 4 to occur. Even if the burr is chemically etched, some recess sometimes remains. The position of the terminal formed with the burr becomes different from the original crystalline tissue. Thus, the improper mounting ratio due to the burr occurred in the conventional one becomes 0%.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semiconductor device using a lead flake 11, and particularly to improving the contact state between an external terminal led out of the sealing resin and a foil-like conductive pattern. It is something.

[Technical background of the invention]

Conventionally, individual semiconductor elements and integrated circuit elements are die-bonded to a so-called lead frame, and then electrical continuity is achieved between the electrodes and terminals of the element by wire bonding, and then these are sealed with resin (10) as shown in Figure 3. The terminal (11) led out from the sealing resin is connected to the desired circuit to perform its respective function. It turns out.

This terminal may be extended in a straight line, or in some cases, as shown in Fig. 3 and Fig. 4, which is an enlarged view of part A, the terminal is led out from the sealing resin, bent downward, and then provided with a step. Generally, the tip portion is fixed by solder or the like to a conductive layer constituting the desired circuit described above, that is, it is mounted on a device. This conductive layer has overwhelmingly often used a conductive pattern provided on a printed circuit board, but recent mounting technology tends to require higher density and surface mounting, and from this point of view, polyimide resin and Cu A foil pattern with a thickness of about 35 μm provided with a conductive layer has come to be used. Moreover, the thickness thereof is becoming thinner, and a multilayer structure is also being explored, and in this multilayer structure, the Cu conductive layer must also become thinner.

Since such foil-like patterns can be folded into a small size as needed, the circuit itself can be stored in a small volume, making it extremely convenient for cameras, etc., and its range of use is expected to continue to expand. .

Incidentally, in the production of lead frames, cutting by press is the mainstream method instead of etching, and currently Cu or Cu alloys are also used in addition to Fe--Ni alloys.

[Problems with background technology]

A lead frame obtained by cutting a metal material into a desired shape by a pressing process inevitably has metal residues (hereinafter referred to as "paris") at the ends thereof. Furthermore, in order to adjust the length of the external terminal (11) of the lead frame as shown in FIG. 3, the punch (12) and receiver are cut by the stand (15) as shown in FIG. Paris (13) shown in is generated. When a resin-sealed semiconductor device having such external terminals was mounted on a device, an accident occurred in which the conductive pattern (14), which was extremely thin with a thickness of about 35 μm, was cut by the pads, as shown in FIG. Although this paris depends on factors such as the material and thickness of the material to be cut, it is known that pars can occur up to a maximum of about 200 μm, and countermeasures against this are strongly desired when using foil patterns.

[Purpose of the invention]

The present invention provides a novel semiconductor device that eliminates the above-mentioned drawbacks, and particularly provides a good connection with a foil pattern.

[Summary of the invention]

In order to achieve the above object, in the present invention, bulk is added to the tip portion of the external terminal that contacts the foil pattern.
A method was adopted in which a region with a crystal structure different from that of the bulk crystal was created, and the structure gradually changed between this region and the bulk crystal structure to form a continuous crystal structure. Specific means for this include crushing the lead terminal on which the burr is formed, causing the burr to peel off from the base to create a depression, and further dissolving the burr by etching.

As a result, a crystal structure different from that of the bulk is formed in the part where the flakes have occurred, and the frequency of damage to the foil pattern is drastically reduced.

[Embodiments of the invention]

The present invention will be explained in detail with reference to FIGS. 1 and 2.

As mentioned above, when assembling semiconductor devices, there are overwhelmingly many methods that utilize so-called lead frames, and the following embodiments will be described with an eye toward integrated circuit devices.

Integrated circuit devices with a large number of external terminals are usually assembled into a so-called DIP type lead frame. A terminal is formed in a centripetal manner, and at the centripetal position is located a bed portion which is engaged with a connecting piece provided continuously on the frame, and an integrated circuit element is die-bonded thereto. Although the number of units depends on the characteristics of the equipment such as a wire bonder, which will be described later, usually about 20 units can be used in series.

After die-bonding the integrated circuit elements separated from the semiconductor wafer as described above, the bed portion of such a lead frame is electrically connected between the electrodes formed on the integrated circuit elements and the lead frame terminals by wire bonding. After the connections are made, the integrated circuit element is further covered and protected with a sealing resin, and the terminals of the lead frame (hereinafter referred to as external terminals) are led out of the sealing resin to complete the assembly process.

A protective film is usually applied to the external terminal led out of the sealing resin by a plating process, and the external terminal is further molded into a predetermined shape. This is because when mounting this resin-sealed integrated circuit element on equipment, the process is made easier by bending and molding external terminals that are fixed to predetermined circuit patterns coated with adhesive. It can be so. Usually, a printed circuit board is used as this circuit pattern, but in the present invention, a foil-like conductive pattern is used. Specifically, a conductive pattern made of Cu is formed on a polyimide resin with a thickness of 35 μm. It can be folded up and stored in an extremely small volume.

On the other hand, the lead frame is currently formed into a predetermined shape through a pressing process, and some cracks remain at the ends thereof. Further, as described above, the external terminal is formed with a bent portion in order to adjust its length and ensure contact with the foil pattern by the molding process. This length adjustment is the fifth
As shown in the figure, the receiver is made by placing the external terminal (11) on the stand (15) and lowering the cutting punch (12) there. As a result, the tip of the external terminal (11) has a paris (13) is formed.

As shown in Fig. 1, the external terminal (3) with this prong (2) is placed under the stand (1), and the prong (2) formed at the tip is moved up and down with the punch (14). I squeeze it, but
When this paris remains at the tip of the external terminal (11), a part (3) having a composition different from that of the bulk, or when the paris peels off from the root part due to compression and a slight depression (5) is formed. There is also. It is also possible to remove this paris by chemical etching, but this will also result in some dents.

However, as a result of these measures, a structure different from that of the original crystal is formed at the position of the external terminal where paris has occurred. A partial cross-sectional view of the external terminal after removing the electrode (2) by this mechanical and chemical means is shown in FIGS. 2(a) and 2(b).

〔Effect of the invention〕

When attaching resin-sealed semiconductor devices to equipment that requires automatic surface mounting, the required number of semiconductor devices are taken out using a specific jig and fixed to a foil-like conductive pattern coated with adhesive. As described above, since a pressing force is applied to the external terminal led out of the sealing resin, the thin conductor pattern is cut by the remaining pads.

In the process of cutting the external terminals, which causes this burr, a burr of approximately 100 μm is generated after 300,000 uses.

However, the semiconductor device according to the present invention, that is, the external terminal led out of the sealing resin, has a crystal structure different from the original crystal at its tip, so the mounting defect rate that occurs in conventional equipment is 5%. 50% is almost eliminated, making it possible to create a highly reliable semiconductor device and improve the reliability of equipment that uses this semiconductor device.

In the semiconductor device according to the present invention, the external terminal has a paris of 30 μm.
Even if it occurs at a height of
Even at 50 μm, it is only 5%, and the effect on mass production is extremely large.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the manufacturing process in this implementation, Figure 2 (a)
(b) is a sectional view of the resulting external terminal, FIG. 3 is a sectional view of a conventional resin-sealed semiconductor element, and FIG. 4 is a partially enlarged view showing the state of attachment to the foil conductive pattern. The perspective view shown in FIG. 5 is a cross-sectional view showing the process of cutting the external terminal.

Claims (1)

[Claims] When connecting conductively to the electrodes of a semiconductor element sealed with resin and contacting and fixing external terminals led out of the resin to a foil-like conductive pattern, a crystal structure different from that of the bulk crystal is formed near this contact part. A semiconductor device comprising: