JPH1131773A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the reliability of soldering of a semiconductor device to a printed board when the soldering work is executed, by a method wherein the outer lead parts of a lead frame which are exposed without being resin- sealed are chamferred by an etching treatment. SOLUTION: A ferric chloride aqueous solution 9 is sprayed on outer lead parts 10 of a lead frame 1 which are exposed without being resin-sealed to etch the parts 10, and the parts 10 are rinsed and are dried. The square parts of the parts 10 of the frame 1 which are obtained in such a way are chamferred. Then, the chamferred outer lead parts 10 are dipped in a molten solder bath and a solder layer 5 is applied on the parts 10. The layer 5 is applied on the outer peripheries of these obtained outer lead parts 10 of mediate products in a uniform thickness. Lastly, the parts 10 are cut in a prescribed length and the cut parts 10 are bent with a prescribed angle, whereby a semiconductor device is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method for manufacturing the same. More specifically, the present invention relates to a resin-sealed semiconductor device widely used as an electronic component such as an IC and an LSI, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 5 is a partially sectional front view showing a manufacturing process of a conventional resin-encapsulated semiconductor device.

FIG. 5A is an explanatory front view showing a state where a semiconductor chip is mounted on a lead frame coated with a silver paste, and FIG. 5B is a front view showing a gold wire between the mounted semiconductor chip and the lead frame. (C) is a partial cross-sectional front view showing a state in which the wire-bonded semiconductor chip and the lead frame are resin-sealed with a semiconductor sealing epoxy resin; () Is a partial cross-sectional front view showing a state in which the outer lead portion of the lead frame that has not been resin-sealed is coated with solder, and (e) is obtained by cutting the outer lead portion of the lead frame coated with solder into a predetermined length. FIG. 2 is a partial cross-sectional front view illustrating a resin-sealed semiconductor device formed by bending the semiconductor device at a predetermined angle afterwards.

In FIG. 5, 1 is a lead frame,
Reference numeral 2 denotes a semiconductor chip, 3 denotes a gold wire, 4 denotes an epoxy resin for semiconductor encapsulation, 5 denotes a solder layer, and 10 denotes an outer lead portion of the lead frame 1.

[0005] First, a silver paste (not shown) is applied on the lead frame 1, then the semiconductor chips 2 are mounted thereon as shown in FIG. 5 (a), and then these are placed in an oven at a predetermined temperature. The semiconductor chip 2 is bonded on the lead frame 1 by hardening the paste.

Next, as shown in FIG. 5B, the semiconductor chip 2 and the lead frame 1 are electrically connected by wire bonding with a gold wire 3.

Next, as shown in FIG. 5C, the semiconductor chip 2 wire-bonded with the gold wire 3 and the lead frame 1 are molded with an epoxy resin 4 for semiconductor encapsulation and are integrally resin-sealed.

Next, as shown in FIG. 5D, the outer lead portion 10 of the lead frame 1 which is exposed without being resin-sealed is immersed in a molten solder bath (not shown) to form a solder layer 5.
Coating.

Finally, as shown in FIG.
The resin-encapsulated semiconductor device is obtained by cutting the outer lead portion 10 coated with the resin into a predetermined length and bending it at a predetermined angle.

By the way, there are an etching method and a punching method as a manufacturing method of a lead frame. Of these, a widely used punching method has a dramatically higher productivity. In a method of manufacturing a lead frame by a punching method, a copper alloy plate material is fed into a punching device equipped with a predetermined die and punched into a predetermined shape.

The outer lead portion 10 of the lead frame manufactured by this punching method has a rectangular cross section, and all four corners have a pointed shape. Therefore, the four sharp corners of the outer lead portion 10 have extremely poor wettability of the molten solder.

FIG. 6 is an enlarged cross-sectional view of an outer lead portion of a conventional resin-encapsulated semiconductor device.

In FIG. 6, 5 is a solder layer, 6 is a corner, 10
Is an outer lead portion.

As can be seen from FIG. 6, the outer lead portion 1
The solder layers 5 at the four sharp corners 6 of 0 are extremely thin.
As a result, when a semiconductor device having such an outer lead portion is soldered to a printed circuit board, there has been a problem in that defective soldering frequently occurs.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to solve the above-mentioned disadvantages of the prior art and to provide an outer lead portion of a lead frame of a semiconductor device. Has excellent wet solder wettability,
It is an object of the present invention to provide a semiconductor device and a method of manufacturing the same, which can significantly improve soldering reliability when soldering a semiconductor device obtained as a result to a printed circuit board.

[0016]

The gist of the present invention lies in the following two points.

(1) A semiconductor device in which an outer lead portion of a lead frame that is exposed without being resin-sealed is chamfered by etching.

(2) A method of manufacturing a semiconductor device in which an outer lead portion of a lead frame is chamfered by etching before being immersed in a molten solder bath.

According to the first aspect of the present invention, the lead frame and the semiconductor chip mounted on the lead frame are electrically connected by a bonding wire, and a semiconductor chip peripheral portion electrically connected by the bonding wire is a semiconductor. In a resin-sealed semiconductor device integrally sealed with a sealing resin, a corner portion of an outer lead portion of the lead frame that is exposed without being resin-sealed is chamfered by etching. A semiconductor device.

Here, the chamfer at the corner of the outer lead portion of the lead frame is preferably one having a chamfer radius of 5 μm or more.

The reason why the corner of the outer lead portion is chamfered to a chamfer radius of 5 μm or more is that the wettability of the molten solder deteriorates sharply when the chamfer radius is 5 μm or less.

According to a second aspect of the present invention, a semiconductor chip is mounted on a lead frame via a conductive paste, and the semiconductor chip and the lead frame are electrically connected with a bonding wire. The peripheral portion is integrally resin-sealed with a semiconductor sealing resin, and then the outer lead portion of the lead frame, which is exposed without being resin-sealed, is immersed in a molten solder bath to form a solder layer. In a method of manufacturing a semiconductor device of a resin-sealed type by coating and finally cutting the lead portion to a predetermined length and bending the lead portion to a predetermined angle, the outer lead portion is placed in a molten solder bath. The lead portion is etched and chamfered before immersion in a semiconductor device.

The etching solution used for the etching treatment is preferably an acidic etching solution such as an aqueous solution of ferric chloride or cupric chloride, or an alkaline etching solution such as an aqueous solution of ammonium persulfate.

In the etching process, it is preferable to immerse the outer lead portion in an etching solution or to spray the etching solution onto the outer lead portion by spraying.

If the etching time for the outer lead portion is long, there is a concern that the semiconductor device will be corroded.

[0026]

Next, embodiments of the semiconductor device and the method of manufacturing the same according to the present invention will be described.

(First Embodiment) FIG. 1 is a partially sectional front view showing a manufacturing process of a first embodiment of a method of manufacturing a semiconductor device according to the present invention.

First, a lead frame manufactured by a punching method is prepared.

Next, a silver paste is applied to a portion where the semiconductor chip is mounted on the lead frame prepared above. Next, the semiconductor chip 2 is mounted on the silver paste, and the semiconductor chip 2 is adhered on the lead frame 1 by heating in an oven at a predetermined temperature to cure the silver paste.

FIG. 1A shows a lead frame 1 on which the semiconductor chip 2 thus obtained is mounted.

Next, as shown in FIG. 1B, the semiconductor chip 2 and the lead frame 2 are electrically connected by wire bonding with a gold wire 3.

Next, as shown in FIG. 1C, the semiconductor chip 2 wire-bonded with the gold wire 3 and the lead frame 1 are molded with an epoxy resin 4 for semiconductor encapsulation so as to be integrally resin-encapsulated. I do.

Up to this point, the manufacturing method is the same as the conventional manufacturing method shown in FIGS. 5 (a) to 5 (c).

Next, as shown in FIG. 1D, the ferric chloride aqueous solution 9 is spray-sprayed on the exposed outer lead portions 10 of the lead frame 1 without resin sealing for 5 minutes to perform etching. , Then washed with water and dried.

FIG. 2 is an enlarged cross-sectional view of the outer lead portion thus obtained.

As shown in FIG. 2, the corner 7 of the outer lead portion 10 of the lead frame 1 had a chamfer radius of about 15 μm.

Next, the outer lead portion 1 chamfered
1 was immersed in a molten solder bath (not shown) to coat the solder layer 5, thereby obtaining an intermediate product of a semiconductor device as shown in FIG.

FIG. 3 is an enlarged cross-sectional view of the outer lead portion shown in FIG. In FIG. 3, 5 is a solder layer, and 10 is an outer lead portion.

As can be seen from FIG. 3, the outer periphery of the outer lead portion 10 of the lead frame 1 is coated with a solder layer 5 with a uniform thickness.

Finally, the outer lead portion 10 coated with the solder layer 5 is cut to a predetermined length and then bent at a predetermined angle as shown in FIG. An example was obtained.

The outer lead portion 10 of the semiconductor device according to the embodiment of the present invention thus obtained is coated with a solder layer having a uniform thickness as shown in FIG. The workability of soldering to the substrate was extremely good.

The outer lead portion 10 of the semiconductor device of the comparative example obtained by the conventional manufacturing method as shown in FIG.
As shown in FIG. 6, the corner 6 could be coated with a very thin solder layer. As a result, the workability of soldering the corner 6 to a printed circuit board was extremely poor.

(Second Embodiment) A second embodiment of a method of manufacturing a semiconductor device according to the present invention is basically the same as the first embodiment, but before etching, as shown in FIG. The difference is that an organic protective layer is added to the outer periphery of the epoxy resin 4 mold layer.

The organic protective layer 8 is provided so that the etchant does not penetrate in the next etching step to erode the gold wire 3, the semiconductor chip 2, the lead frame 1, the semiconductor sealing epoxy resin 4, and the like. That's why. After the etching step, the organic protective layer 8 is peeled and removed by spraying an organic solvent or the like.

Here, the organic protective layer 8 was provided by applying a vinyl acetate resin paint on the epoxy resin for semiconductor encapsulation 4 and drying it. Further, the vinyl acetate resin film 8 thus provided was peeled off after spraying a mixed organic solvent of acetone and methanol.

[0046]

According to the semiconductor device and the method of manufacturing the same of the present invention, the wet solder wettability of the outer lead portion of the lead frame can be remarkably improved, and the resulting solder reliability of the semiconductor device to the printed circuit board can be improved. It can significantly improve the properties and is industrially useful.

[Brief description of the drawings]

FIG. 1 is a partially sectional front view showing a manufacturing process of a first embodiment of a method of manufacturing a semiconductor device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an outer lead portion of a semiconductor device obtained by a first embodiment of a method of manufacturing a semiconductor device according to the present invention before solder coating.

FIG. 3 is an enlarged cross-sectional view of an outer lead portion after solder coating of the semiconductor device obtained by the first embodiment of the method of manufacturing a semiconductor device of the present invention.

FIG. 4 is a partially sectional front view of an intermediate product of a semiconductor device obtained by a second embodiment of the method of manufacturing a semiconductor device according to the present invention;

FIG. 5 is an explanatory front view showing steps of a conventional method of manufacturing a resin-sealed semiconductor device.

FIG. 6 is an enlarged sectional view of an outer lead portion of a lead frame of a semiconductor device manufactured by a conventional method of manufacturing a resin-sealed semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Semiconductor chip 3 Gold wire 4 Epoxy resin for semiconductor encapsulation 5 Solder layer 6 Corner part 7 Chamfer part 8 Organic protective layer 9 Etching solution 10 Outer lead part

Claims (7)

[Claims] 1. A lead frame and a semiconductor chip mounted on the lead frame are electrically connected by a bonding wire, and a peripheral portion of the semiconductor chip electrically connected by the bonding wire is a semiconductor sealing resin. In the resin-encapsulated semiconductor device which is integrally resin-encapsulated, the corners of the outer lead portions of the lead frame which are exposed without being resin-encapsulated are chamfered by etching. Characteristic semiconductor device. 2. The semiconductor device according to claim 1, wherein a chamfer at a corner of the outer lead portion of the lead frame has a chamfer radius of 5 μm or more. 3. A semiconductor chip is mounted on a lead frame via a conductive paste, and the semiconductor chip and the lead frame are electrically connected with a bonding wire. Resin sealing integrally with a stopping resin, then dipping the exposed outer lead portion of the lead frame without resin sealing in a molten solder bath to coat a solder layer, and finally In a method of manufacturing a resin-encapsulated semiconductor device by cutting the lead portion to a predetermined length and bending the lead portion to a predetermined angle, before immersing the outer lead portion in a molten solder bath, A method of manufacturing a semiconductor device, wherein the lead portion is chamfered by etching. 4. An etching process is performed after integrally sealing with a resin for semiconductor encapsulation and thereafter providing an organic protective layer on the resin layer for semiconductor encapsulation. The manufacturing method of the semiconductor device described in the above. 5. The etching process according to claim 3, wherein the etching process is performed by etching selected from an aqueous ferric chloride solution, an aqueous cupric chloride solution, and an aqueous ammonium persulfate solution.
The manufacturing method of the semiconductor device described in the above. 6. The method according to claim 3, wherein the etching process is performed by immersing the outer lead portion in an etching solution. 7. The method of manufacturing a semiconductor device according to claim 3, wherein the etching process is performed by spraying an etching solution onto an outer lead portion.