JPH1197468A - Resin sealed semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of mold flashes. SOLUTION: In this method, a resin sealed semiconductor device is manufactured by seal molding a semiconductor chip, by using a sealing resin, on a lead frame which comprises an island 7 for mounting a semiconductor chip, internal leads 2a and external leads 2 arranged around the island 7, tie bars 1 for supporting the leads with a given interval therebetween, and suspension leads 6 for supporting the island 7. Prior to seal molding, side surfaces of the internal leads 2a are covered with a first resin 4 composed of a low-melting- point resin. Further, the first resin 4 is covered with a second resin 3 which has a thermal expansion coefficient larger than that of the sealing resin so as to fill up the spaces between the internal leads 2a, followed by seal molding using the sealing resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art A method of manufacturing a resin-sealed semiconductor device is disclosed in Japanese Patent Application Laid-Open No. 63-87753. This technique will be described with reference to FIGS. FIG.
FIG. 4 is a top view showing a state where resin sealing of the semiconductor device is completed, and FIG. 4 is a partially enlarged view of a side sectional view taken along line AA of FIG. FIG. 5 is a partially enlarged view of a side sectional view taken along line BB of FIG.

In a method of manufacturing a semiconductor device to be sealed with a resin, a semiconductor chip is connected to a lead frame as shown in FIG.
Then, a connection portion between a and the external lead 2 is covered with a heat-resistant seal 11, and then the semiconductor chip portion is sealed with resin to form a resin sealing portion 9. When the resin is sealed, since the sealing resin flows out from the internal lead 2a in the direction of the tie bar 1, the heat-resistant seal 11 is used to reduce the adhesion of the resin to the lead surface and to facilitate the removal of the adhered resin. used.
The tie bar 1 functions to support the internal lead 2a and the external lead 2 at a predetermined interval and at the same time prevent the sealing resin from flowing onto the external lead 2.

[0004] A cross-sectional view of FIG. 4 shows a state in which the surface of the internal lead 2 a is covered with a heat-resistant seal 11, and the sealing resin that has flowed out adheres to the heat-resistant seal 11. The resin attached on the heat-resistant seal 11 is generally called a burr 12. In addition, the cross-sectional view of FIG. 5 shows a state in which the sealing resin flows out of the resin sealing portion 9 to form the burr 12.

[0005] When the heat-resistant seal 11 is peeled off, the burrs 12 adhered to the heat-resistant seal 11 can be mechanically removed. The burrs 12 formed on the leads 2 without being covered with the heat-resistant seal 11 are separated by being pulled by the burrs on the heat-resistant seal. Therefore, generally, the heat-resistant seal 11 is coated as close to the resin sealing portion 9 as possible.

[0006]

SUMMARY OF THE INVENTION The first of the prior arts described above.
The problem is that when the heat-resistant seal 11 is peeled off after the resin sealing and the burr 12 is removed, the adhesion between the internal lead 2a and the burr 12 is high and the burr 12 cannot be completely removed.

A second problem of the above-mentioned prior art is that the heat-resistant seal 11 affixed on the internal lead is pressed by a mold during resin sealing, causing deformation of the internal lead. The smaller the lead interval, the more easily the thermal expansion of the heat-resistant seal is affected, and the more easily the lead is deformed.

An object of the present invention is to provide a method of manufacturing a resin-encapsulated semiconductor device which can completely remove burrs and does not cause lead deformation during resin encapsulation, which solves the above-mentioned problems of the prior art. Aim.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a resin sealing method in which a semiconductor chip is mounted on an island of a lead frame which supports an external lead and an internal lead at a predetermined interval by a tie bar, and is molded with a sealing resin. In the method of manufacturing a mold semiconductor device, before encapsulation molding, a side surface of the internal lead is coated with a first resin made of a low-melting point resin, and the first resin is coated on the first resin more than the encapsulation resin. After filling the internal lead gap with a second resin having a large thermal expansion coefficient, the internal lead gap is sealed and molded with the sealing resin.

[0010] As the first resin of the present invention, a thermoplastic resin having a low melting point can be used. Further, as the second resin, a thermosetting resin or an ultraviolet curing resin having a larger coefficient of thermal expansion than the sealing resin can be used.

When the first resin is sealed with a sealing resin, the first resin melts at a temperature and flows out of the internal leads due to thermal expansion of the second resin and is removed. The second resin remains between the internal leads, and this resin can prevent the sealing resin from flowing out excessively. After the encapsulation molding, the volume of the second resin between the internal leads is reduced by cooling, and a gap is formed between the internal leads and the second resin. Therefore, the second resin is easily removed. In this case, the deformation of the internal lead can be prevented.

[0012]

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

FIG. 1 illustrates a method of manufacturing a resin-encapsulated semiconductor device according to an embodiment of the present invention, in which first and second resins are formed between leads before being encapsulated and molded with an encapsulating resin. FIG. 13 is an enlarged plan view of a main part of the semiconductor device, showing a state after the above. In FIG. 1, the illustration of the semiconductor chip and the like is omitted.

In FIG. 1, reference numeral 1 denotes a tie bar, 2 denotes an external lead, 2a denotes an internal lead, and 3 and 4 denote a second resin and a first resin formed on the side surface of the internal lead 2a. Reference numeral 6 denotes a suspension lead, reference numeral 7 denotes an island for mounting a semiconductor chip, and reference numeral 10 denotes a frame for connecting the suspension lead and the tie bar. Reference numeral 5 denotes a sealing line for sealing molding.

There is a gap on the lead side surface between the sealing line 5 and the tie bar where the first and second resins are not formed. The function of this gap will be described later, but providing this gap is also an important point of the present invention.

Next, a method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention will be described in detail with reference to FIG.

FIGS. 2A to 2D show a first method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention.
FIG. 4 is an enlarged plan view of a main part of a lead of a lead frame for explaining a second resin coating step and a sealing molding step using a sealing resin.

First, after connecting the semiconductor chip to the island of the lead frame (see FIG. 1), as shown in FIG. 2A, a first resin 4 made of a low melting point resin is provided on the side surfaces of the leads between the internal leads 2a. Is formed to a thickness of 20 to 50 μm. As the first resin, a thermoplastic resin having a low melting point is suitable, and a vinyl chloride resin or a polystyrene resin that melts at a sealing molding temperature (for example, 170 to 190 ° C.) can be used. Etc. can be formed.

Next, the second resin 3 is coated on the first resin 4 by a screen printing method or the like so as to fill the gap between the internal leads 2a and is cured. As the second resin, a resin having a larger thermal expansion coefficient than that of the sealing resin and melting at the sealing molding temperature can be used. In the present invention, as the sealing resin, a powdery thermosetting epoxy resin to which a fifo such as silica having a thermal expansion coefficient of 10 to 20 × 10 ⁻⁶ / ° C. is added is used. The amount of resin filler is reduced, and a thermosetting or ultraviolet-curing liquid epoxy resin having a larger thermal expansion coefficient (for example, 50 to 70 × 10 ⁻⁶ / ° C.) than the cured product of the sealing resin can be used. . This second
It is also an important point of the present invention to use a resin which has a large thermal expansion coefficient and does not melt at a sealing molding temperature as the resin. Next, an epoxy resin as a sealing resin is poured from the gate of the mold heated to a temperature of 170 to 190 ° C. for 5 to 10 seconds to seal the semiconductor chip with the resin. At the temperature at which the resin is sealed, the first resin 4 between the internal leads 2a is melted,
2 flows out from between the internal leads 2a due to the thermal expansion of the resin 3, and the second resin 3 remains between the internal leads 2a (FIG. 2).
(B). The second resin thermally expands and is mechanically held between the internal leads 2a. The sealing resin 8 flows toward the sealing line (FIG. 2 (c)), and in order to drive the second resin 3 between the internal leads 2a out of the sealing line 5, the sealing line 5 and the tie bar 1 are used. Internal lead 2a between
Is filled with the second resin 3. Since the movement of the second resin 3 is stopped by the tie bar 1, the flow of the sealing resin 8 also stops at the sealing line (FIG. 2).
(D)). That is, it is possible to prevent the overflow of the sealing resin as in the related art, and to prevent the occurrence of burrs due to the sealing resin. In addition, the formation length of the resin 3 may be obtained in advance so that the flow of the sealing resin 8 just stops at the sealing line 5. If the second resin 3 is cooled after the sealing molding, the volume of the second resin 3 is reduced and a gap is formed between the internal leads 2a, and the second resin 3 can be easily removed from between the internal leads 2a by blowing high-pressure air or mechanical vibration. Therefore, there is no problem of lead deformation at the time of peeling off the heat-resistant seal as in the related art.

[0020]

The first effect of the present invention is that the gap from the sealing line to the tie bar is filled with a resin (second resin) having a larger thermal expansion coefficient than the sealing resin at the time of sealing molding. Therefore, it is possible to prevent burrs from occurring due to the sealing resin.

The second effect of the present invention is that the first resin, which is a low melting point resin, is coated on the side surface of the internal lead, and the first resin flows out from between the internal leads and is removed by thermal expansion of the second resin. In addition, since the thermal stress due to the second resin can be reduced, and the second resin after the encapsulation molding can be easily removed, the deformation of the internal lead does not occur.

[Brief description of the drawings]

FIG. 1 is a view illustrating a method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention, after forming first and second resins between internal leads before sealing and molding with a sealing resin. FIG. 4 is an enlarged plan view of a main part of the semiconductor device showing the state of FIG.

FIG. 2 is an enlarged view of a main part of a lead of a lead frame for explaining first and second resin coating steps and a sealing molding step using a sealing resin in the method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention; It is a top view.

FIG. 3 is a top view showing a state in which resin sealing of a conventional semiconductor device is completed.

FIG. 4 is a partially enlarged view of a side sectional view taken along line AA of FIG. 3;

FIG. 5 is a partially enlarged view of a side sectional view taken along line BB of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tie bar 2 External lead 2a Internal lead 3 Second resin 4 First resin 5 Sealing line 6 Suspended lead 7 Island 8 Sealing resin 9 Resin sealing portion 10 Frame 11 Heat resistant seal 12 Burr

Claims (6)

[Claims] 1. A method of manufacturing a resin-encapsulated semiconductor device, comprising: mounting a semiconductor chip on an island of a lead frame for supporting an external lead and an internal lead at a predetermined interval by a tie bar; Before the sealing molding, a side surface of the internal lead is coated with a first resin made of a low melting point resin, and a second resin having a larger coefficient of thermal expansion than the sealing resin is formed on the first resin. A method of manufacturing a resin-encapsulated semiconductor device, comprising: filling a gap between the internal leads by coating with a resin; and sealing and molding with a sealing resin. 2. The resin-sealed semiconductor according to claim 1, wherein the first resin and the second resin before the sealing are formed such that a gap is formed between the internal leads and the tie bar. Device manufacturing method. 3. The method for manufacturing a resin-encapsulated semiconductor device according to claim 1, wherein a thermoplastic resin is used as said first resin. 4. The method according to claim 3, wherein a vinyl chloride resin or a polystyrene resin is used as the thermoplastic resin. 5. The method of manufacturing a resin-encapsulated semiconductor device according to claim 1, wherein a thermosetting resin or an ultraviolet-curing resin is used as the second resin. 6. The method of manufacturing a resin-encapsulated semiconductor device according to claim 5, wherein a thermosetting or ultraviolet-curing epoxy resin is used as said second resin.