KR19980034803A - Lead frame with detachable die pad and semiconductor package using same - Google Patents

Abstract

The present invention relates to providing a semiconductor package having improved reliability by forming a die pad of a lead frame in which a semiconductor chip is adhesively fixed by an adhesive, the semiconductor chip having a plurality of bonding pads formed thereon; A detachable die pad in which at least two die pads to which the semiconductor chip is adhesively fixed by an adhesive are separated in a short side direction; Leads respectively corresponding to the bonding pads; Bonding wires electrically connecting the bonding pads and leads; And a molding resin encapsulating an electrical connection portion including the semiconductor chip. It is to improve the reliability of the semiconductor package by providing a semiconductor package having a removable die pad comprising a.

Description

Lead frame with detachable die pad and semiconductor package using same

The present invention relates to a lead frame and a semiconductor package using the lead frame, and more particularly, to a lead frame and a semiconductor package using the die pad of the lead frame in which the semiconductor chip is adhesively fixed by an adhesive. .

In today's semiconductor industry, plastic-based epoxy encapsulation resins (EMCs) are used to protect semiconductor chips from the external environment, to facilitate electrical connection with external terminals and electronic devices, and to ensure reliability of functions during semiconductor chip operation. : epoxy molding compound is used as the semiconductor package body. In addition, a plastic semiconductor package using an epoxy encapsulating resin has been widely used at home for the purpose of securing reliability of the semiconductor package.

A general semiconductor package using such an epoxy encapsulation resin will be described with reference to the drawings.

1 is a cross-sectional view showing a conventional semiconductor package according to the prior art.

FIG. 2 is a plan view illustrating a general lead frame used in the semiconductor package of FIG. 1.

First, FIG. 1 illustrates that a semiconductor chip 10 having a plurality of bonding pads 12 formed thereon is adhesively fixed to an upper surface of a die pad 40 with an adhesive 20, and a plurality of leads on the side of the bonding pad 12. 50 is arranged, and the leads 50 and the bonding pads 12 are electrically connected by wires 30. The electrical connection part including the semiconductor chip 10 is sealed with the molding resin 60, and the molding resin 60 is a plastic-based epoxy resin.

In FIG. 2, the die pad 40 to which the semiconductor chip is adhesively fixed is connected to the guide rail 44 by a tie bar 42, and a plurality of leads 50 are formed around the die pad 40. The dam bar 52 is connected to the guide rail 44 across the lead 50, and the guide rail 44, the tie bar 42, the die pad 40, the lead 50, and the dam bar ( 52 shows an integrated structure of the lead frame 100. Such a method of forming the lead frame 100 is manufactured by an etching method or a stamping method, and the lead frame serves as a skeleton for fixing and fixing a semiconductor chip and making an electrical connection with the outside. have.

However, the plastic semiconductor package described above with reference to FIGS. 1 and 2 saturates together with the interfacial peeling between the constituent composite materials of the semiconductor package due to thermal stress in the semiconductor package during reliability test to ensure reliability after assembly. There is a fear that cracking of the semiconductor package occurs due to water vapor pressure. In the step-by-step crack mechanism of the semiconductor package according to the progress of the reliability test, the semiconductor chip is encapsulated with a molding resin at about 175 ° C. which is a stress-free state in the molding process, and the molding resin The semiconductor package encapsulated with is cooled to room temperature (25 ° C.) again to contain residual stresses along with warpage of the semiconductor package.

Then, during the thermal cycling test process, interface delimitation occurs due to the difference in coefficient of thermal expansion between each interface, that is, the epoxy molding resin and each interface of the lead frame, the adhesive, and the semiconductor chip. A soak process is a process of forcibly absorbing moisture into a semiconductor package at a temperature of about 85 ° C. and a humidity of 85%, where moisture absorbed into the semiconductor package is reflow soldering. ) Is set at a high temperature of about 240 ℃. The moisture present in the semiconductor package then generates water vapor pressure, causing a typical pop-corn crack. This causes a fatal defect of the semiconductor package.

Therefore, as a method for removing cracks in the plastic semiconductor package, the design of the die pad structure is optimized, such as a dimple formed on the bottom of the die pad or a slot formed on the die pad. there was. Another method for preventing cracks is to strengthen the adhesion between the semiconductor chip and the die pad, and to enhance the filler shape and the flexural strength of the molding resin, thereby increasing the water vapor pressure due to moisture absorption or moisture in the semiconductor package. To withstand.

However, the crack generation of the semiconductor package is not completely eliminated, and a path through which moisture in the air penetrates into the semiconductor package is formed through a gap through the interface between the outer lead of the lead frame and the molding resin and through each surface of the molding resin. Water penetrates in bulk form.

In the prior art for preventing moisture infiltration, a nickel-alloy layer is formed on the surface of the lead frame to increase adhesion to the plastic-based molding resin, thereby infiltrating moisture through a gap between the external lead and the molding resin. Prevention techniques are used. However, such a technique does not completely prevent moisture penetration and has the disadvantage of increasing the cost of forming a nickel-alloy layer.

Accordingly, an object of the present invention is to provide a semiconductor package in which the factors of crack generation due to water vapor pressure generated at the chip and die pad interface of the semiconductor package described above and cost increase due to plating of the lead frame are removed.

1 is a cross-sectional view showing a conventional semiconductor package according to the prior art.

FIG. 2 is a plan view illustrating a general lead frame used in the semiconductor package of FIG. 1. FIG.

3 is a plan view showing a lead frame having a detachable die pad according to the present invention;

4 and 5 are another exemplary plan view showing a lead frame having a detachable die pad according to the present invention.

Fig. 6 is a plan view showing a semiconductor chip bonded to a lead frame having a detachable die pad according to the present invention.

7 is a cross-sectional view taken along a line 7-7 and encapsulating the lead frame to which the semiconductor chip of FIG. 6 is bonded with a molding resin.

Description of the main symbols in the drawings

10 semiconductor chip 12 bonding pad

20: adhesive 30: wire

40, 240: die pad 42, 260: tie bar

44, 210: guide rail 50, 250: lead

52, 230: dam bar 60: molding resin

100, 200: lead frame 220: guide hole

270: yaw portion 280: connection bar

In order to achieve the above object, a die pad which is supported by a tie bar extending from one side of the guide rail, leads formed around the die pad, and a dam bar formed across the leads and connected to the guide rail are integrally formed. In a lead frame for a package, a lead frame having a detachable die pad is provided, wherein two or more die pads are separated in a short side direction.

In addition, a semiconductor chip in which a plurality of bonding pads are formed to achieve the other object; A detachable die pad in which at least two die pads to which the semiconductor chip is adhesively fixed by an adhesive are separated in a short side direction; Leads respectively corresponding to the bonding pads; Bonding wires electrically connecting the bonding pads and leads; And a molding resin encapsulating an electrical connection portion including the semiconductor chip. It provides a semiconductor package having a detachable die pad comprising a.

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

3 is a plan view showing a lead frame having a detachable die pad according to the present invention.

4 and 5 are another exemplary plan view showing a lead frame having a detachable die pad according to the present invention.

6 is a plan view showing a state in which a semiconductor chip is bonded to a lead frame having a detachable die pad according to the present invention.

FIG. 7 is a cross-sectional view taken along a line 7-7 and encapsulating the lead frame to which the semiconductor chip of FIG. 6 is bonded with a molding resin.

First, FIG. 3 is formed by dividing a die pad 240 into a short side to be bonded to a semiconductor chip, and the separated die pad 240 is connected to the guide rail 210 by a tie bar 260 to be supported. It shows how it is. In addition, a plurality of leads 250 are formed around the die pad 240, the dam bar 230 is connected to the guide rail 210 across the leads 250, and the guide rail 210. The guide hole 220 formed at is used to adjust the position of the lead frame 200. In addition, the guide rail 210, the die pad 240, the tie bar 260, the lead 250, the dam bar 230, and the like are integrally formed by a stamping method. In addition, the separated die pads 240 are formed at both symmetrical predetermined intervals, and a recessed portion 270 is formed in a portion of the die pad 260 in the direction of the lead 250.

4 has a die pad 240 separated in the same way as the lead frame 200, and only a concave recessed portion of the die pad 240 is formed in a streamlined shape 275. As shown in FIG. It shows how it is done.

The die pad portion 240 of the lead frame 200 according to the present invention is formed by separating the die pad portion 240 in the short side direction and recessed into the die pad 240 surface in the lead 250 direction. 270 is formed to reduce the adhesion interface area with the semiconductor chip. This can minimize defects such as voids occurring at the bonding interface between the semiconductor chip and the die pad, and this recessed portion can disperse the direction in which the die pad is stretched due to thermal stress.

FIG. 5 illustrates a shape in which the die bar 240 in which the connection bar 280 is separated is connected to the lead frame 200 in which the above-described die pad is separated. This is provided in order to maintain the support strength of the semiconductor chip when the semiconductor chip is bonded to the separated die pad 240. That is, the connection bar 280 is formed on a surface where the yaw portion 270 of the separated die pad 240 is not formed, and the sag of the die pad is connected by connecting the separated die pads 240. It serves to prevent.

As described above, the lead frame having the separated die pad according to the present invention may be formed by a stamping method, which is a general lead frame manufacturing method, and may be manufactured in a simple form in which the die pad of the lead frame is separated.

6 shows that a semiconductor chip 10 having a plurality of bonding pads 12 formed thereon is bonded to a lead frame 200 having separate die pads 240 according to the present invention, and corresponds to the bonding pads 12, respectively. A plurality of leads 250 are shown to be electrically connected. Subsequently, after the semiconductor package assembly process is completed, FIG. 7, which is a view taken along the line 7-7 of FIG. 6, has a semiconductor chip 10 in which a plurality of bonding pads 12 are formed. The chip | tip 10 has shown the shape which adhere | attached the detachable die pad 240 in which the die pad is isolate | separated in the short side direction with the adhesive agent 20. As shown in FIG. In addition, the molding pads 60 are electrically connected to each other by the bonding wires 30 and the leads 250 corresponding to the bonding pads 12 and encapsulate the electrical connection portions including the semiconductor chip 10. ) Is a semiconductor package.

Thus, the semiconductor package using the separated die pad is filled with a molding resin between the separated die pad to increase the bonding force between the semiconductor chip and the molding resin to suppress the occurrence of cracks, the die pad is separated, the die pad area is reduced and adhesion The interface can be reduced.

The recess and the streamlined shape may be formed in the direction of the leads of the die pad to minimize the die pad area.

Therefore, the semiconductor package having the detachable die pad according to the present invention makes the central portions of two separate die pads in the short side length direction of the die pad in a concave recessed shape or streamline, thereby reducing the reliability of the die pad area. It is possible to suppress the occurrence of defects by reducing the area where water vapor pressure is generated, and the molding resin is filled between the die pad gaps separated in the long direction of the semiconductor package, thereby increasing the adhesive force between the semiconductor chip and the molding resin, thereby preventing the occurrence of defects such as popcorn cracks. There is an advantage.

Claims (10)

In the lead frame for a semiconductor package formed of a die pad which is supported by a tie bar extending from one side of the guide rail, a plurality of leads formed around the die pad, and a dam bar formed across the lead and connected to the guide rail , 2. A lead frame having a detachable die pad, wherein at least two die pads are separated in a short side direction. The lead frame having a detachable die pad according to claim 1, wherein a recessed surface of the separated die pad is recessed to form a recess. The lead frame according to claim 1, wherein the separated die pad is connected by a connecting bar. 3. The lead frame having a separate die pad according to claim 2, wherein the recessed recessed portion of the separated die pad has a streamlined shape. 3. The lead frame according to claim 2, wherein the separated die pads in which the lead direction surfaces are recessed are connected by connecting bars. A semiconductor chip in which a plurality of bonding pads are formed; A detachable die pad in which at least two die pads to which the semiconductor chip is adhesively fixed by an adhesive are separated in a short side direction; Leads respectively corresponding to the bonding pads; Bonding wires electrically connecting the bonding pads and leads; And A molding resin encapsulating an electrical connection portion including the semiconductor chip; A semiconductor package having a detachable die pad, characterized in that it comprises a. The semiconductor package with a detachable die pad according to claim 6, wherein a recessed surface of the separated die pad is recessed to form a recess. 7. The semiconductor package according to claim 6, wherein the separated die pads are connected by connection bars. 8. The semiconductor package according to claim 7, wherein the recessed recessed portions of the separated die pads are streamlined. 8. The semiconductor package according to claim 7, wherein the separated die pads in which the lead direction surfaces are concave are connected by connecting bars.