JPH04320054A - Semiconductor lead frame - Google Patents

Abstract

PURPOSE: To decrease defective rate of a semiconductor lead frame, equipped with a die pad where a semiconductor chip is mounted and a lead and to improve the product quality by making the lead as long as or longer than the die pad and thus preventing the die pad from deforming. CONSTITUTION: A lead 13 provided with a die pad 11 where a semiconductor chip 12 is adhered atop is formed on a support frame 15 of the lead frame. On the support frame 15, leads 14 of length L12 equal to or longer than the length L11 of the die pad are formed on both the sides of the lead 13, provided with the die pad 11. The lead frame has the semiconductor chip 12 adhered to the die pad 11, and the semiconductor chip 12 which is adhered to the die pad 11, and the bonding part 14 of the lead 14 are connected by an extremely thin wire through a wire-bonding process. The leads 13 and 14 which are exposed to outside the semiconductor chip 12 after being molded with an epoxy resin are cut, so that they can be mounted on a socket and a substrate.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION This invention relates to a semiconductor lead frame, and more specifically, the present invention relates to a semiconductor lead frame, and more particularly, a die pad to which a semiconductor chip is bonded is constructed so as to be protected from external physical interference by leads. This prevents deformation of the material, thereby reducing the defective rate and improving quality.

0002

[Background Art] Recently, as semiconductors have become highly integrated, it has become necessary to have a large number of input/output terminals, enable high output and high speed operation, and improve heat dissipation. The need for
Currently, packages are becoming more diverse, such as becoming smaller and thinner.

[0003] Conventional packages have been constructed as shown in FIGS. 1 and 2 as straight type lead frames in which only heat dissipation capability is considered. That is, a die pad 1 to which a semiconductor chip 2 is bonded is formed at one end of a lead 3, and leads 4 are formed on both sides of the lead 3 so that the die pad 1 is exposed to the outside. Above lead 3,
4 are connected to a support frame 5.

[0004] Such lead frames are made of strips (S
It is configured like a trip, and during the assembly process, loading and feeding
ing).

That is, a large number of semiconductor chips formed on a wafer are individually separated through a dicing process, the separated semiconductor chips are placed on a die pad 1 of a lead frame in a die attach process, and ultrafine wires are bonded in a wire bonding process. (not shown) to connect the semiconductor chip 2 and the bonding portions 4a of the leads 4, and then molding is performed using a high purity epoxy resin. Finally, the leads 3 and 4 are cut into an arbitrary shape according to the mounting method for mounting on a socket or a board.

However, in the conventional lead frame as described above, only the improvement of the heat dissipation ability of the semiconductor chip 2 was considered, and the area of the die pad 1 was increased. Therefore, the length L of the die pad 1 from the support frame 5 is
1 was longer than the length L2 of the lead 4 from the support frame 5 and was exposed to the outside. Therefore, during the above-mentioned assembly process, if an external physical force is applied to the die pad 1 of the lead frame (for example, during molding with epoxy resin, etc.), the die pad 1 will move toward the left or right side as shown in FIG. This may cause the semiconductor chip 2 to change its position.

As a result, the shape of the loop of the wire connected to the bonding portion 4a of the semiconductor chip 2 and the lead 4 may be deformed in the direction in which the die pad 1 is deformed. That is, the wire is pulled in the opposite direction to the direction in which the die pad 1 is deformed, resulting in wire sagging, and if the die pad 1 is severely deformed, the wire neck is broken, which has an adverse effect on the product.
This causes problems such as short circuits, an increase in defective rate, and a decrease in quality.

[0008]

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems. It is an object of the present invention to provide a semiconductor lead frame that can prevent deformation of a die pad, reduce defective rates, and improve product quality.

[0009]

Means for Solving the Problems In order to achieve the above object, the present invention provides a semiconductor lead frame including a die pad on which a semiconductor chip is mounted and leads located on both sides of the die pad, in which the die pad is attached to a package. The length of the leads is made equal to or longer than the length of the die pad so as to be protected from physical interference that may occur during the assembly process.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 3 and 4 are drawings for explaining a semiconductor lead frame according to an embodiment of the present invention.

That is, in the support frame 15 of the lead frame,
Leads 13 are formed with die pads 11 at their tips for bonding semiconductor chips 12. Furthermore, in the support frame 15, leads 14 having a length L12 that is equal to or longer than the length L11 of the die pad are formed on both sides of the lead 13 on which the die pad 11 is provided.

[0013] Such a lead frame is formed in the form of a strip, and in this state, the assembly process is carried out by loading and feeding operations. In the assembly process, a large number of semiconductor chips 12 formed on the wafer are individually cut and separated by a dicing process, which is a method of applying breaking stress to the wafer along the dicing line to cut and separate the chips. After that, each separated semiconductor chip 12 is attached to the die pad 11 by a die attach process such as a resin bonding method, a soldering method, an Au-Si process method, etc.
Glue to. Next, through the wire bonding process,
Using a thermocompression method (TC method), an ultrasonic method (US method), etc., the semiconductor chip 12 bonded to the die pad 11 of the lead frame and the bonding part 14a of the lead 14 are bonded with an ultra-fine wire (not shown). Connect. Thereafter, the semiconductor chip 12 is molded with high-purity epoxy resin using a low-voltage transistor molding method. Then, the leads 13 and 14 exposed to the outside of the molded semiconductor chip 12 are arbitrarily cut so that they can be mounted on a socket or a board.

According to the embodiment described above, during the assembly process,
When a physical force is applied to the die pad 11 of the lead frame from the outside by molding with epoxy resin or the like, only the leads 14 formed in a straight type on both sides of the die pad 11 are deformed. This protects the die pad 11, and even if a physical force is applied, only the loop shape of the wire connected to the adhesive portion 14a of the semiconductor chip 12 and the lead 14 is deformed, and the die pad is not affected. As a result, product yield and reliability are improved. Further, the lead frame of the present invention is suitably used even when the size of the semiconductor chip 12 bonded to the die pad 11 is small or when the heat dissipation ability of the package is small.

[0015]

As described above, the present invention protects the die pad from external physical interference by protecting the die pad to which a semiconductor chip is bonded with leads that are equal to or longer than the die pad. Deformation is prevented and yield and product quality can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the main parts of a conventional semiconductor lead frame.

FIG. 2 is a plan view showing a deformed state of a conventional semiconductor lead frame.

FIG. 3 is a plan view showing essential parts of a semiconductor lead frame according to the present invention.

FIG. 4 is a plan view showing a deformed state of the lead frame according to the present invention.

[Explanation of symbols]

11 Die pad 12 Semiconductor chip 13. Lead 14a Bonding part 15 Support frame

Claims (1)

[Claims] 1. In a semiconductor lead frame equipped with a die pad and leads on which a semiconductor chip is mounted, the die pad 11 is arranged such that the die pad 11 is protected from physical interference that occurs during the package assembly process. A semiconductor lead frame characterized in that a length L12 of leads 14 provided on both sides is equal to or longer than a length L11 of the die pad.