JPH11274392A - Manufacture of resin encapsulated semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a resin encapsulated semiconductor device with small pitches and many pins, while keeping the high reliability of a resin package. SOLUTION: In this manufacturing method, outer leads 5 of a lead frame 1 are coupled to each other with resin tie-bars 8 comprising polyether amide resin, polyether imide resin, polyether amide imide resin, or acrylic resin and a semiconductor chip is then mounted on a die pad 3 and encapsulated with a package of epoxy resin. Next, the device is immersed for three to five minutes in an organic solvent comprising dimethyl formaldehyde, dimethyl acetic amide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, m-cresol, pyridine, or cyclohexane, of which the temperature is maintained in the range of 60 to 90 deg.C. This process enables burrs of the package together with these as of the resin tie-bars to be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art In a resin-encapsulated semiconductor device, the leads of a lead frame are connected to each other with tie bars in advance so that the leads do not deform during resin encapsulation, prevent a dam from leaking, or dislocate. It is common to remove it after resin sealing. The tie bar includes a metal tie bar type formed integrally with the lead frame and a resin tie bar type formed of an electrically insulating resin.

With the miniaturization of semiconductor devices and the increase in the number of pins,
A lead frame having a very large number of outer leads and having a very narrow pitch of 0.5 mm or less has been widely used.

In a semiconductor device using a metal tie bar type lead frame, the tie bar is cut and removed using a punch. However, as the pitch of the leads becomes narrower, the punch becomes finer. Removal by punching is not suitable for mass production because it not only makes it difficult but also reduces its wear resistance. As a tie bar that can cope with such a narrow lead pitch, a method of forming with a resin has been developed and used.

More specifically, a resin tie bar is formed at a position that partially overlaps with the resin package, and is left as it is even after the completion of the semiconductor device, and slightly away from the edge of the resin mold so as not to overlap with the resin package. There is a method in which a resin tie bar is formed at a position where the resin tie is formed, and is removed after molding.

In the latter method, there are proposed a method of crushing the resin tie bar with a punch to form a crack and then removing the resin tie bar by applying a jet of water, or a method of irradiating a high energy light such as a laser beam to remove the resin tie bar. ing.

[0007]

However, when the resin tie bar is formed so as to partially overlap the resin package and is left even after the completion of the semiconductor device, cracks may occur in the tie bar portion or in the vicinity of the tie bar of the package. Therefore, there is room for consideration in terms of reliability.

On the other hand, the method of removing the resin tie bar after the formation of the resin package has an advantage that it does not affect the resin package such that the reliability is reduced. However, on the processing side, since the burr of the package and the resin tie bar generated at the time of resin molding are separately removed, many steps are required for the removal.

An object of the present invention is to provide a method capable of simultaneously removing burrs and a resin tie bar of a resin package without impairing the reliability of the resin package.

[0010]

In a method of manufacturing a resin-encapsulated semiconductor device according to the present invention, a resin tie bar for connecting leads of a lead frame outside a resin package forming region is formed, and a semiconductor is mounted on the lead frame. After mounting the chip and sealing the resin, the chip is immersed in an organic solvent for a predetermined time to selectively dissolve and remove the resin tie bar. And
The resin for forming the package is less soluble in the organic solvent than the resin for forming the tie bar.

By selecting the tie bar and the resin constituting the package as described above, the resin tie bar is selectively removed without the package being damaged by the organic solvent. Since the burr of the resin package is thin and small, the burr is also dissolved and removed when the resin tie bar is removed.

Further, in the above-mentioned method, a polyetheramide resin, a polyetherimide resin, a polyetheramideimide resin, or an acrylic resin is used for forming a resin tie bar, and an epoxy resin is used for forming a resin package. By using dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, m-cresol, pyridine, or cyclohexano as the organic solvent, the selectivity of resin tie bar removal is further enhanced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1A, first, a thin plate of an iron-nickel alloy, for example, a 58Fe / 42Ni alloy is etched into a predetermined pattern or punched by using a die, etc. Is prepared. In the lead frame 1 of this example, a die pad 3 on which a semiconductor chip is mounted is arranged in a central portion of the frame 2.
The die pad 3 is held on the frame 2 by suspending leads 4 connecting the four corners thereof and the frame 2 respectively. Also, frame 2
A number of outer leads 5 are extended from each of the four sides of the die pad 3, and inner leads 6 formed integrally with the outer leads 5 extend toward the die pad 3 from the ends thereof, and the tip portion is a die pad. 3 is located in the vicinity.

In the step of forming the lead frame 1, all the metal parts between the outer leads 5 and between the inner leads 6 are removed, and a metal member for connecting them is not left.

Next, along the resin mold boundary line 7 of the lead frame 1, a narrow band-shaped resin tie bar 8 is formed at a predetermined interval G in a region outside the resin mold region surrounded by the boundary line 7. And outer lead 5
At the end on the inner lead 6 side.

As the resin used for forming the resin tie bar, a polyether amide resin, a polyether imide resin, or a polyether amide imide resin can be used. These resins have lower adhesiveness to the lead frame 1 than epoxy resin. Among these resins, polyether amide imide resin is a material having a great advantage in practical use because it is easy to apply with relatively low viscosity and has high strength.

For applying the tie bar resin, a dispenser is used, and a method of applying an uncured resin with a predetermined width while moving the dispenser, a screen printing method, or the like is applied.

As shown in FIG. 1B, the thickness of the resin tie bar 8 is equal to or slightly larger than that of the lead frame 1. The width W may be such that it does not deform or move against the pressing force of the burr generated during resin molding. According to the experiment, the width W is from 0.3 to
It is preferably within the range of 1.0 mm. In this example, the interval G is set to about 1/2 of the width W. If the resin tie bar 8 is formed so as to overlap with the resin package, a crack is likely to occur in the resin package. Therefore, it is desirable to provide the gap G.

After the resin tie bar 8 is formed, a semiconductor chip is attached to the die pad 3 by a known method, and the electrode pad and the tip of the inner lead 6 are connected by a thin gold wire or the like, and then loaded into a mold. , Resin mold boundary line 7
2 is sealed with a synthetic resin such as an epoxy resin, and as shown in FIG. 2, a semiconductor chip, a die pad 3 on which the semiconductor chip is mounted, an inner lead 6, and a conductive wire for electrically connecting the semiconductor chip to the semiconductor chip. Are integrally coated. Furthermore, it is rinsed with hot water with industrial water.

Thus, the semiconductor device 10 having the resin tie bars 8 arranged in parallel on the four sides of the resin package 9 and held by the frame of the lead frame 1 is obtained.

Next, as shown in FIG. 3, the semiconductor device 10 including the lead frame 1 is immersed in an organic solvent 11. By this immersion treatment, burrs on the resin tie bar 8 and the resin package 9 are removed. In FIG. 3,
Reference numeral 12 denotes a liquid tank.

Examples of the organic solvent include dimethylformamide, dimethylacetamide, dimethylsulfoxide, N
-Methyl-2-pyrrolidone, m-cresol, pyridine or cyclohexanone can be used.
Of these, N-methyl-2-pyrrolidone is practical because of its low toxicity and easy handling.

In this example, N-methyl-2-
Pyrrolidone was used, the temperature was in the range of 60 to 90 ° C., and the immersion time was 3 to 5 minutes. When the solvent temperature is lower than 60 ° C. or the immersion time is shorter than 3 minutes, there is a possibility that the resin tie bar 8 is not completely removed and remains in a state attached to the lead frame 1. If the solvent temperature is too high or the immersion time is too long, the resin package 9
The solvent itself is damaged by the solvent, and the surface is more likely to change in quality such as discoloration. Therefore, the solvent temperature is preferably 90 ° C. or less, and the immersion time is preferably 5 minutes or less.

The burrs of the resin package 9 can also be removed by the immersion treatment at the above-mentioned solvent temperature and immersion time.

Further, an organic solvent 1 is prepared by using an ultrasonic vibrator.
By applying the ultrasonic vibration to 1, the removal of the resin tie bar 8 and the like can be made more effective.

After completion of the above-mentioned removal treatment, the organic solvent is washed away with industrial water or water having a purity equal to or higher than that, if necessary.

After the resin tie bar 8 and the resin burrs are removed, the lead frame 1 is stamped into a predetermined shape by a known method to complete the semiconductor device shown in FIG.

[0029]

According to the manufacturing method of the present invention, the leads of the lead frame are connected to each other with a resin tie bar outside the resin package forming area, the semiconductor chip is sealed with the resin package, and then immersed in an organic solvent for a predetermined time. The resin package is removed without causing any substantial damage to the resin package by the solvent, so that the resin tie bar can be easily removed without deforming the lead frame and without reducing the sealing reliability of the resin package. Can be.

Further, since the resin burr generated during the formation of the resin package can be removed simultaneously with the resin removal,
There is no need to add a step for removing resin burrs, and it is easy to implement and a semiconductor device with a narrow lead pitch can be manufactured at low cost.

Further, in the above-mentioned method, a polyether amide resin, a polyether imide resin, or a polyether amide imide resin is used for forming a resin tie bar, and an epoxy resin is used for forming a resin package. Use of dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, m-cresol, pyridine, or cyclohexanone to reliably and selectively remove resin tie bars and burrs in a series of production lines can do.

[Brief description of the drawings]

FIG. 1A is a plan view showing a part of a lead frame on which a resin tie bar is formed for explaining an example of an embodiment of a method of manufacturing a semiconductor device according to the present invention; FIG. Main part sectional view

FIG. 2 is an essential part perspective view showing a state after resin molding, for describing an example of an embodiment of a method of manufacturing a semiconductor device according to the present invention;

FIG. 3 is a view for explaining a immersion treatment step in a solvent in an example of an embodiment of a method of manufacturing a semiconductor device according to the present invention.

4A is a plan view of a semiconductor device according to the present invention, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Frame 3 Die pad 4 Suspension lead 5 Outer lead 6 Inner lead 7 Resin mold boundary line 8 Resin tie bar 9 Resin package 10 Semiconductor device 11 Organic solvent 12 Liquid tank

Claims (3)

[Claims] A first step of forming a resin tie bar for connecting a lead outside a resin package forming region of a lead frame including a frame and a lead having one end connected to the frame; After arranging a semiconductor chip at a predetermined position of the lead frame, a resin package is formed in the resin package forming region to seal at least the semiconductor chip, and is held by the lead in the frame of the lead frame. A second step of fabricating the semiconductor device, a third step of immersing the semiconductor device in an organic solvent, and selectively dissolving and removing the resin tie bar, and after removing the resin tie bar, A fourth step of cutting a predetermined portion of the resin, wherein the resin for forming the package is smaller than the resin for forming the tie bar with respect to the organic solvent. A method for manufacturing a resin-encapsulated semiconductor device which is hardly soluble in all. 2. A resin tie bar is formed of a polyether amide resin, a polyether imide resin, a polyether amide imide resin, or an acrylic resin, and a resin package is formed of an epoxy resin.
The method for manufacturing a resin-encapsulated semiconductor device according to claim 1, wherein the resin tie bar is removed by immersion in dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, m-cresol, pyridine, or cyclohexanone. 3. The method according to claim 1, wherein N-methyl-2-pyrrolidone is used as an organic solvent, and the temperature is in the range of 60 to 90 ° C.
3. The method according to claim 1, wherein the immersion time is 3 to 5 minutes.