JP3049466B2 - Lead frame for semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a semiconductor device.

[0002]

2. Description of the Related Art In general, a semiconductor device has a semiconductor chip (hereinafter, referred to as a chip) bonded and mounted on a pad of a lead frame, a chip terminal and an inner lead are connected by a bonding wire, and a portion within the inner lead is packaged with a resin or the like. Then, the outer leads projecting from the package are formed into a predetermined shape and manufactured. In some cases, the pad is formed separately from the lead frame and bonded with a double-sided adhesive insulating tape or the like.

[0003] In a semiconductor device, high integration of a memory and multi-function of a logic are achieved, and miniaturization is required. Since this requires an increase in the number of input / output signal pins, the number of pins must be increased and the pitch thereof must be fine.

On the other hand, on the other hand, it is strongly desired that the signal processing speed of the semiconductor device be increased during use. However, since the frequency of the signal is increased and the amount of heat is increased, it is necessary to promote the heat dissipation and suppress the temperature rise. There is.

As a technique for suppressing a temperature rise of a semiconductor device, there is a technique in which a heat radiating plate made of copper or a copper alloy having high thermal conductivity is provided below a pad. (For example,
-84541).

[0006]

The installation of a heat radiating plate is effective because it has an effect of suppressing a rise in temperature. However, the radiator plate is bonded below the pad from the inner lead through an insulating tape as described in, for example, JP-A-63-249342, but the tape has a moisture absorbing effect. When used as a semiconductor device, moisture absorbed may evaporate due to a rise in temperature, expand, and cause cracks. In addition, the moisture has a corrosive effect on the lead frame, the chip, and the bonding wire, thereby deteriorating the function and shortening the service life.

As described above, copper or copper alloy is often used for the heat sink because of high thermal conductivity. However, for example, when assembling a semiconductor device, the insulating tape for bonding is used for some reason. If a flaw, a cut, etc. occur due to the above, there is a possibility that the insulating property is deteriorated at the place and a short circuit occurs.

According to the present invention, there is provided a semiconductor device capable of strictly securing the insulating property of a heat radiating plate installed on a lead frame, using a high heat conductive material for the heat radiating plate while maintaining the insulating property, and increasing the speed of signal processing. The purpose is to obtain a lead frame. In addition, by increasing the insulation of the heat sink, the joint with the inner lead is made strong without causing an electrical short,
It is an object of the present invention to provide a semiconductor device lead frame in which even if the inner leads have a large number of pins and a fine pitch, the inner leads are securely fixed.

[0009]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a lead frame for a semiconductor device in which a heat radiating plate is laminated on inner leads, and a heat radiating plate made of an insulated metal plate is bonded through an adhesive. In the semiconductor device lead frame laminated in a region within the inner lead portion. Further, the insulation treatment of the metal plate is formed by attaching a sol of a metal alkoxide, drying and firing.

[0010]

According to the present invention, a heat radiating plate made of an insulated metal plate having a high thermal conductivity is laminated on the lower or upper part of the inner lead. A semiconductor device is obtained in which the insulation between the heat sink and the inner leads is strictly secured, has no dielectric, and can speed up signal processing.

Since the heat radiating plate is insulated, it does not necessarily require an expensive adhesive such as a double-sided adhesive tape when bonding and laminating with the inner lead. It is planned.

[0012] The insulation treatment is formed by attaching a metal alkoxide sol to a metal plate, drying and firing.
The insulating property is high, and the adhesiveness to the metal plate is strong, so that there is no occurrence of defective insulation at the time of assembling the semiconductor device.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In the drawings, 1 is an inner lead, 2 is an outer lead, and
It is continuous. 3 is a tie bar for the inner lead 1
And the outer lead 2.

In the lead frame 4 of this embodiment, the pads for mounting the chips are not formed together with the inner leads 1 and the outer leads 2, and the heat radiation is formed from a separate metal plate as shown in FIG. The plate 5 is provided with a pad portion 6, and the heat radiating plate 5 is adhered to the lower portion of the inner lead 1 of the lead frame 4 so as to be laminated.

The heat radiating plate 5 is desirably made of a metal plate having high heat conductivity, for example, a material such as copper or a copper alloy, and is subjected to an insulation treatment. Insulation treatment is Si, Zr, Ti, A
A metal alkoxide such as 1 or Y, for example, tetraethoxycin of Si alkoxide, Zr tetraisopropoxide, Ti isopropoxide, Al isopropoxide, or the like, and a sol using water or an alcohol as a solvent are immersed and coated. Alternatively, it is formed by attaching to a metal plate by spraying or the like, drying and firing. The insulating film formed by this treatment has strong adhesion and insulating properties, and the above-mentioned properties do not deteriorate even if the temperature is repeatedly increased thereafter.

The heat radiating plate 5 is bonded to the lower portion of the inner lead 1 via an adhesive as shown in FIG. 3, and is laminated on the inner lead 1 to fix each lead. Thus, for example, the lead frame 4 has a large number of pins and a narrow lead pitch, and does not deform or displace even if the mechanical strength is weak. The central portion of the radiator plate 5 becomes the pad portion 6, so that the wire bonding between the chip 10 mounted thereon and the inner lead 1 can be performed without any trouble.

Reference numeral 7 denotes a side rail, and reference numeral 8 denotes a guide ball.

In this embodiment, the pads were not formed on the lead frame 4 together with the inner leads 1 and the outer leads 2. However, when the inner leads 1 and the outer leads 2 were formed, the pads 9 were formed as shown in FIG. It may be. In this case, the insulated heat radiating plate 5 is laminated below the inner lead 1 and the pad 9 via an adhesive.

Further, the heat sink 5 can support and fix the inner lead 1 from above, and in this case, the heat can be dissipated upward.

[0020]

According to the lead frame for a semiconductor device of the present invention, a heat radiating plate made of a metal plate which has been subjected to insulation treatment is bonded and laminated at a position within the inner lead region.
An expensive adhesive such as a double-sided adhesive insulating tape is not necessarily used for the bonding. In addition, since the tapes are not required, there is no moisture absorption phenomenon, and there is no deterioration in function or cracks in the resin-sealed package, resulting in excellent reliability and long life.

Further, since the inner leads are fixed and supported by the heat radiating plate, even if the inner leads are narrow at a small pitch with a large number of pins, the inner leads are surely prevented from being deformed or displaced such as front sagging and lead shift. Wire bonding between the inner lead and the chip mounted on the pad is performed.

The heat-dissipating plate is formed by depositing a sol of metal alkoxide, drying and firing, so that the heat-dissipating plate has a high insulating property, and is temporarily subjected to rubbing force when assembling or transporting the semiconductor device. Also, there is no deterioration in insulation.

[Brief description of the drawings]

FIG. 1 is a plan view of a lead frame according to an embodiment of the present invention.

FIG. 2 is a view showing a heat sink in a lead frame according to one embodiment of the present invention.

FIG. 3 is a side view of the lead frame according to the embodiment of the present invention.

FIG. 4 is a plan view of a lead frame according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner lead 2 Outer lead 3 Tie bar 4 Lead frame 5 Heat sink 6 Pad part 7 Side rail 8 Guide hole 9 Pad 10 Chip

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/50

Claims (1)

(57) [Claims] In a lead frame for a semiconductor device in which a heat radiating plate is laminated on an inner lead portion, a heat radiating plate made of an insulated metal plate is laminated in a region within the inner lead portion via an adhesive, A lead frame for a semiconductor device, wherein the insulation treatment of a metal plate is formed by attaching a sol of a metal alkoxide, drying and firing.