KR19990002948A - Lead frame with inner lead gripper - Google Patents

Abstract

The present invention relates to a structure of a lead frame, and more particularly, to form a gripper that can fix internal leads between internal leads, thereby improving coplanarity of the internal leads and a thermal process required for a semiconductor manufacturing process. In order to prevent structural deformation of the inner lead even after passing through, for this purpose, a gripper made of resin or the like is formed between the inner leads near the ends of the inner leads to replace the inner leads instead of the conventional polyimide tape. Disclosed is the structure of the lead frame to be fixed, and also by using this structure can reduce the rate at which the semi-finished product up to the wire bonding process deviates from the specification (SPEC), thereby reducing the defective rate of the finished product after the final molding, additionally Clamp Position in Wire Bonding Process The degree of freedom of the ping area and the heat block can be improved.

Description

Lead frame having inner lead gripper

The present invention relates to a structure of a lead frame, and more particularly to a lead frame having an inner lead gripper formed of a resin or the like between the inner leads in order to maintain the coplanarity of the inner leads.

Due to the continuous progress of high integration of semiconductor packages, packages are becoming thin and short, and thus quality problems that are not found in existing products appear. In particular, as the package becomes thinner, even if the positions of the semiconductor chip, the lead frame pad, and the inner lead of the lead frame, which are located within the package, are slightly changed, the bonding wire adjacent to the surface of the package may cause a defect to protrude out of the package.

This defect is caused by the influence of encapsulant flow such as epoxy molding compound (EMC) in the subsequent molding process as the state of semi-finished product which wire bonding is completed during the assembly process of semiconductor package is more severe than the specification of product. Etc., the degree of defects is increased.

One of the factors causing such a defect is a polyimide tape attached to the inner lead portion of the lead frame. That is, although the polyimide tape attached to improve co-planarity is made of a thermosetting resin, thermal shrinkage and expansion may occur, and particularly after die attach during the assembly process of the semiconductor package. In the curing process (Oven Cure) to proceed to a large change. As a result of this change, the structural balance of the inner leads is broken, resulting in loss of coplanarity, resulting in a defect in the package structure.

Figure 1a is a perspective view of the lead frame structure in which the polyimide tape is used in a perspective view, Figure 1b is a perspective view of the deformation of the lead frame of Figure 1a through a thermal process in a center perspective view It was. FIG. 1A illustrates a structure in which a polyimide tape 60a is attached to an upper surface of the inner leads 30a, and the inner leads 30b are formed after the thermal process in the process of assembling a package using the lead frame having such a structure. The loss of structural balance due to the thermal change of the mid tape 60b is illustrated in FIG. 1B. In addition, when using the polyimide tape as described above, the position to which the polyimide tape is attached is located on the upper or lower surface of the inner lead may be followed in the subsequent wire bonding process. In other words, when the tape is attached to the upper surface of the inner lead, the clamping area (not shown) that fixes the inner lead should be applied to avoid the position where the tape is attached. There is a restriction that a groove into which a tape is inserted must be formed in an upper surface of a heat block (not shown) supporting the lid from below.

The present invention relates to a structure of a lead frame, and to provide a structure of a lead frame having grippers between inner leads for the purpose of improving the coplanarity of the inner leads.

In addition, the present invention provides a gripper formed between the inner lead, thereby minimizing the amount of deformation of the inner lead and provides a structure that can improve the design freedom of the clamp and the heat block in the wire bonding process during the semiconductor assembly process. .

Figure 1a is a perspective view showing a part of a lead frame using a conventional polyimide tape,

1B is a perspective view illustrating an example in which a part of the lead frame of FIG. 1A is deformed after a thermal process;

2 is a plan view of a lead frame having an inner lead gripper according to the present invention;

3 is a perspective view showing a part of a lead frame having an inner lead gripper according to the present invention;

4A and 4B are schematic views illustrating a process of forming the inner lead gripper according to the present invention.

Description of the main parts of the drawing

30a, 30b, 130: inner leads 60a, 60b: polyimide tape

100: lead frame 110: die pad

120: tie-bar 140: external leads

150: dam-bar 160: Gripper

210: Syringe 220: Liquid resin

230: Press Block 240: Support Block

The present invention relates to a structure of a lead frame having grippers between inner leads to improve co-planarity of the inner leads.

The structure of a lead frame used in a semiconductor package product includes a die pad to which a semiconductor chip is attached and releases heat generated from the chip, a plurality of internal leads and an external substrate to be electrically connected to a bonding pad of the chip. It is mounted on and formed of a plurality of external leads that are electrical connection paths. In addition, a tie bar for supporting the die pad and a dam bar for preventing the encapsulation resin from leaking out of the package encapsulation area are formed.

The structure of the lead frame formed according to the present invention has a gripper formed of a resin or the like between the inner leads near the ends of the inner leads for the purpose of improving the coplanarity of the inner leads. The polyimide tape used in the conventional lead frame structure is continuously attached to one surface of the inner leads, which thermally expands and contracts in the curing process and consequently deforms the inner leads, whereas the gripper formed according to the present invention is a resin. It is formed of a material such as a short and positioned between the inner leads so as not to lose the structural balance of the inner leads and tie-bar even after the curing process.

As the material for forming the gripper, a resin of a series such as a package encapsulant such as an epoxy resin may be used, and an adhesive such as liquid polyimide may be used to have better adhesion.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a plan view illustrating a lead frame having an inner lead gripper according to the present invention, and FIG. 3 is a perspective view of the lead frame illustrated in FIG.

2 and 3, the lead frame 100 includes a rectangular die pad 110 formed at a central portion thereof, a tie-bar 120 for fixing the die pad, and an inner lead arranged in series around the die pad. And outer leads 140 formed integrally with the rods 130 and the inner leads. In addition, a dam-bar 150 is formed between the inner lead 130 and the outer lead 140 to prevent the encapsulation resin from flowing out of the package encapsulation region in the package assembly process.

The gripper 160 is formed between the inner leads 130 and is bonded to the inner leads 130 on both sides to improve coplanarity. At this time, a thin resin layer (not shown) may remain on the upper surfaces of the inner leads 130, but this may have little effect on the coplanarity of the inner leads 130 and may also be applied to the clamps during wire bonding. (Not shown) does not place a constraint on the contact.

The step of forming the gripper using the resin can be carried out simultaneously when the resin dam-bar is formed and can be formed in the same manner, and the process of forming the gripper is simply illustrated in FIGS. 4A and 4B. Referring to this, the syringe 210 (syringe) containing the liquid resin 220 is placed on the lead frame placed on the support block 240 in a direction perpendicular to the direction in which the inner leads 130 are arranged. While moving, the liquid resin 220 in the syringe 210 is applied using the pressure of compressed air or the like. At this time, by adjusting the viscosity of the liquid resin in consideration of the interval and thickness between the inner lead 130, by compressing the upper surface of the liquid resin 220 is applied using a tool such as a compression block 230 (Press Block), The liquid resin 220 on the upper surfaces of the inner leads 130 may be filled with a gap between the inner leads. Then, the liquid resin 220 is cured by applying heat to form a gripper.

The present invention improves the coplanarity of the inner leads by forming a gripper between the inner leads of the lead frame, and an example in which the lead frame after the thermal process in the package assembly process is structurally deformed by thermal deformation of the polyimide tape. prevent.

In addition, the present invention removes the constraints on the clamping position of the upper surface of the inner lead and the upper surface of the heat block which the lower surface of the inner lead contact, which are required in the wire bonding process, by forming a gripper between the inner leads.

Claims (4)

A plurality of internal leads electrically connected to the semiconductor chip; A plurality of outer leads integrally formed with the inner leads; And A gripper for fixing the inner leads; In the lead frame comprising: And the gripper is formed between the inner leads to have the same planarity as the inner leads. The lead frame according to claim 1, wherein the lead frame includes a die pad to which the semiconductor chip is attached and a tie-bar for fixing the die pad. The lead frame according to claim 1, wherein the gripper is formed of a liquid resin of a package encapsulation resin series. The lead frame according to claim 1, wherein the gripper is formed of liquid polyimide.