TW201604998A - Lead frame and manufacturing method thereof - Google Patents

Abstract

The present invention provides a lead frame capable of allowing the surface of a terminal for lead connection to be different from the surface of a terminal for external connection, and the manufacturing method thereof. The lead frame (50, 51) is made of a metal plate, wherein at least a part of its backside is exposed as terminals for external connection and a semiconductor device is mounted on its surface. Therefore, the lead frame can be treated as a component of a surface mount type semiconductor package. A plating layer (30) capable of being bonded to the semiconductor device is formed on the surface and side, and a thin film (40) is attached to the backside.

Description

Lead frame and method of manufacturing same

The present invention relates to a lead frame and a method of manufacturing the same.

In order to meet the demand for miniaturization and thinning of a semiconductor package, for example, a SON or QFN type package is known as a surface mount type package in which an external connection terminal is exposed on the back surface of a semiconductor package.

The conventional lead frame used in such a semiconductor package does not use a mask for partially forming a plating layer, but has a plating layer sequentially formed of Ni, Pd, and Au on the entire surface. Since the plating layer can be wire-bonded and has reliability in connection with solder, both the internal terminal for wire bonding with the mounted semiconductor element and the external connection terminal for external connection can be used (for example, refer to Patent Document 1).

Patent Document: Japanese Laid-Open Patent Publication No. 2005-79524

However, in many cases, the bonding property in wire bonding and the connection reliability with solder in the connection of the external connection terminals do not necessarily coincide, and depending on the application, it may be desirable to form a wire bonding with the semiconductor component. The plating of the internal terminal used is a metal plating layer different from the plating layer formed on the external connection terminal for external connection. In this case, it is not necessary to uniformly form the same plating layer on the entire surface, and it is necessary to make the plating layer formed on the internal terminal different from the plating layer formed on the external terminal, and in the manufacturing step, it is often necessary to make the internal terminal. The plating forms a plating layer with external connection terminals to form a different manufacturing process.

Therefore, an object of the present invention is to provide a lead frame capable of making the surface of the terminal for wire bonding a surface different from the terminal for external connection, and a method of manufacturing the same.

In order to achieve the above object, a lead frame according to an aspect of the present invention is formed of a metal plate, at least a part of which is exposed as an external connection terminal, and a semiconductor element is mounted on the surface, so that it can be used as a surface-mounted semiconductor. a packaged member; a bonding plating layer capable of bonding to the semiconductor element is formed on the surface and the side surface, and a film is attached to the back surface.

According to another aspect of the present invention, in a method of manufacturing a lead frame, the lead frame is exposed to an external connection terminal on a rear surface, and is used for a surface mount type semiconductor package in which a semiconductor element is mounted on a surface; a manufacturing method comprising: a step of processing a metal plate to form a lead frame pattern; a step of attaching a film on a back surface of the lead frame pattern; and using the film as a mask to form a plating layer on a surface and a side surface of the lead frame step.

A method of manufacturing a lead frame according to still another aspect of the present invention, wherein the lead frame exposes an external connection terminal on a rear surface, and is used for a surface mount type semiconductor package in which a semiconductor element is mounted on a surface; the lead frame a manufacturing method comprising: a step of processing a metal plate to form a lead frame pattern; a step of forming a first plating layer on the entire surface of the lead frame pattern; a step of attaching a film on a back surface of the lead frame pattern; The film serves as a mask, and a step of forming a second plating layer on the surface and the side surface of the lead frame.

According to the present invention, it is possible to form a suitable plating layer for bonding purposes.

10‧‧‧ lead frame pattern

11‧‧‧Semiconductor component mounting area

12‧‧‧Terminal area

15‧‧‧Metal sheet

20, 30‧‧‧ plating

40‧‧‧ film

50, 51‧‧‧ lead frame

60‧‧‧Semiconductor components

70‧‧‧ lead

80‧‧‧Resin

Fig. 1 is a cross-sectional structural view showing an example of a lead frame according to a first embodiment of the present invention.

Fig. 2 is a view showing a series of steps of an example of a method of manufacturing a lead frame according to Embodiment 1 of the present invention; wherein Fig. 2(a) is a view showing a preparation step of forming a metal plate of a lead frame; b) is a view showing a step of forming a lead frame pattern; FIG. 2(c) is a view showing an example of a film attaching step; and FIG. 2(d) is a view showing an example of a plating step.

3 is a cross-sectional structural view showing an example of a lead frame according to a second embodiment of the present invention.

Fig. 4 is a view showing a series of steps of an example of a method of manufacturing a lead frame according to a second embodiment of the present invention; wherein Fig. 4(a) is a view showing an example of a preparation step of a metal plate; b) is a view showing an example of a step of forming a lead frame pattern; FIG. 4(c) is a view showing an example of a first plating layer forming step; and FIG. 4(d) is a view showing an example of a film attaching step. Fig. 4(e) is a view showing an example of the second plating step.

FIG. 5 is a view showing an example of a surface mount type semiconductor package obtained by using the lead frame of the second embodiment.

FIG. 6 is a view showing an example of a method of shipping the lead frames 50 and 51 according to the first and second embodiments of the present invention.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

1 is a view showing a cross-sectional configuration of an example of a lead frame according to the first embodiment of the present invention. In FIG. 1, a lead frame 50 according to a first embodiment of the present invention includes a lead frame pattern 10, a bonding plating layer 30, and a film 40. Bonding plating 30 formed on the lead frame pattern 10 on the top and side. Further, the film 40 is attached to the lower surface of the lead frame pattern 10.

Before describing the lead frame of the first embodiment in detail, a surface mount type semiconductor module using a lead frame according to an embodiment of the present invention will be described.

Fig. 5 is a view showing an example of a surface mount type semiconductor module using a lead frame according to an embodiment of the present invention. In FIG. 5, a semiconductor element 60 is mounted on the surface of the lead frame 51, and is entirely sealed by a resin 80. The lead frame pattern 10 has a central semiconductor element mounting region 11 and terminal regions 12 provided on both sides thereof, and the semiconductor element 60 is provided on the semiconductor element mounting region 11. The terminal 61 of the semiconductor element 60 is connected to the terminal region 12 through the lead 70 through wire bonding. Here, the upper surface of the terminal region 12 serves as an internal terminal for bonding, and the lower surface serves as an external connection terminal. In FIG. 5, the film 40 is attached to the lower surface of the whole, and when the film 40 is peeled off, the lower surface of the terminal region 12 is exposed, and it becomes an external connection terminal electrically connectable to the external device. As the lead frame of the present embodiment, a member which is such a surface-mounted semiconductor module can be used.

Referring back to Fig. 1, a lead frame 50 according to the first embodiment of the present invention will be described in detail.

The lead frame pattern 10 is a metal pattern in which a metal plate is processed into a shape of a lead frame. The metal plate may be composed of various metal materials suitable for the lead frame, or may be composed of, for example, a copper material or a copper alloy material. Further, as described in FIG. 5, the lead frame pattern 10 has at least a region in which a semiconductor element is mounted, a bonding internal terminal that electrically connects terminals of the semiconductor element to each other by wire bonding, and a terminal for external connection. External connection terminal for electrical connection. In the lead frame of the present embodiment, the semiconductor element is mounted on the surface side of the lead frame pattern 10, and the bonding terminal connected to the terminal of the semiconductor element by wire bonding is also formed on the surface side. In Figure 1 In the middle, the upper side corresponds to the surface side, and the lower side corresponds to the back side.

In FIG. 1, a plating layer 30 is formed so as to cover the upper surface (surface) and the side surface of the lead frame pattern 10. Since the surface of the lead frame pattern 10 constitutes a terminal for bonding, the plating layer 30 is composed of a bondable plating material. The plating layer 30 can be determined depending on the type, use, and the like of the mounted semiconductor element 60, and may be made of, for example, silver (Ag).

A film 40 is attached to the back surface of the lead frame pattern 10. Accordingly, when the film 40 is peeled off, the lead frame pattern 10 is exposed. As described in FIG. 5, the back surface of the lead frame pattern 10 functions as an external connection terminal that can be electrically connected to an external device. Thereby, the surface of the metal material constituting the lead frame pattern 10 functions as an external connection terminal, and in the case of a copper material or a copper alloy material, the surface thereof becomes an external connection terminal.

The film 40 can function as a mask in the plating step, and can also function as a mask when the resin is sealed, and is selected from a material that does not cause resin to flow out. As long as the film 40 can exhibit a function as a mask during plating treatment and resin sealing, various materials can be used. For example, a film made of polyimide can also be used. Polyimine has high heat resistance and can function as a mask when plating and resin sealing, and therefore can be suitably used.

Further, regarding the adhesion of the film 40 to the back surface of the lead frame pattern 10, various adhesives or adhesives can be used. For example, in the case where the above polyimine is used as the film 40, since the polyimide film of the polyimide film is commercially available, such a film tape can also be used. The subsequent attachment of the film 40 to the back surface of the lead frame pattern 10 can be easily performed.

Next, a method of manufacturing the lead frame according to the first embodiment of the present invention will be described with reference to Fig. 2 . Fig. 2 is a view showing an example of a method of manufacturing a lead frame according to Embodiment 1 of the present invention; A diagram of the column steps.

Fig. 2 (a) is a view showing a preparation step of forming a metal plate of a lead frame. First, the metal plate 15 is prepared in a state in which no pattern or the like is formed. Further, the metal plate 15 may be composed of various metal materials depending on the application, or may be composed of, for example, a copper material or a copper alloy material as described above.

Fig. 2(b) is a view showing a step of forming a lead frame pattern. The lead frame pattern 10 is obtained by processing the metal plate 15 into the shape of a lead frame. The processing of the metal plate 15 can be performed by various processing methods including etching processing and press working. The processing method of the metal plate 15 can be determined depending on the cost, processing accuracy, and the like.

The lead frame pattern 10 is formed by the lead frame pattern forming step, and at least the semiconductor element mounting region 11 and the terminal region 12 are formed. Further, although not shown in FIG. 2(b), the lead frame pattern 10 may be formed into a height drop or the like by bending or the like.

Fig. 2(c) is a view showing an example of a film attaching step. In the film attaching step, the film 40 is attached to the back surface (lower surface) of the lead frame pattern 10. As described above, the film 40 is selected from materials which can be masked during the plating treatment and the resin sealing. The film 40 can be attached by using an adhesive, or a film 40 such as a film tape which is initially formed with an adhesive layer on one surface of the film 40 can be used. Further, in the following description, the adhesive which is cured after bonding and the adhesive which remains in the original state without a curing process after bonding are not necessarily strictly distinguished, and an adhesive is included even in the case of an adhesive.

Fig. 2(d) is a view showing an example of a plating step. In the plating step, a plating treatment is performed in a state where the film 40 is attached to the back surface of the lead frame pattern 10. Thereby, the plating layer 30 is formed only on the upper surface (surface) and the side surface of the lead frame pattern 10 which is not covered by the film 40. As the material of the plating layer 30, various plating materials can be used depending on the use, for example, Ag can also be used. To form an Ag coating.

Further, in the plating step, for example, a plating treatment may be performed. In the electroplating, the lead frame pattern 10 is immersed in the plating solution, and the lead frame pattern 10 is used as a cathode, and is energized together with the anode immersed in the plating solution to perform a plating treatment. The film 40 functions as a mask for the plating step, and the plating layer 30 is formed only on the upper surface and the side surface which are not covered by the film 40, and the lead frame 50 is completed.

The upper surface of the plating layer 30 is subsequently used as an internal terminal for bonding, and the lower surface of the lead frame pattern 10 to which the film 40 is attached is used to function as an external connection terminal.

As described above, according to the lead frame of the first embodiment and the method of manufacturing the same, after the lead frame pattern 10 is formed, by attaching the film 40 to the back surface, the upper surface of the terminal region 12 can be easily formed by one plating step. The following is configured as a different surface, and it is possible to flexibly cope with various demands required for the terminals of the lead frame 50.

3 is a cross-sectional structural view showing an example of a lead frame according to a second embodiment of the present invention. In the lead frame 51 of the second embodiment, the entire surface of the lead frame pattern 10 is covered with a plating layer 20, a plating layer 30 is formed on the upper surface and the side surface of the plating layer 20, and a film 40 is attached to the lower surface. The lead frame 50 of one embodiment is different. That is, the plating layer 20 is formed on the surface of the lead frame pattern 10 as a coating layer. In this regard, unlike the lead frame 50 of the first embodiment, the lead frame 50 of the first embodiment is different from the other configuration. It is the same.

In this manner, the entire surface of the lead frame pattern 10 can be covered with the plating layer 20 made of a material different from the plating layer 30, and then the film 40 can be attached to the lower surface to form the plating layer 30. With such a configuration, the surface of the external connection terminal formed on the lower surface of the terminal region 12 is composed of the plating layer 20. That is, in the material of the metal plate 15 which is not used for the lead frame pattern 10, the shape In the case where the plating layer 20 is formed by any of the metal materials and the external connection terminals are formed by any of the metal materials, the surface of the external connection terminal can be made into a desired metal material by the configuration of the lead frame 51 of the second embodiment.

The plating material of the plating layer 20 may be various materials depending on the application. For example, Ni may be used as a substrate layer and formed on the surface of the lead frame pattern 10 to form Pd on the surface of Ni, further in Pd. A plating layer formed by lamination of Au on the surface (hereinafter also referred to as "palladium plating layer"). Such a palladium plating layer formed by sequentially laminating Ni, Pd, and Au from the lower layer is generally used as a plating layer suitable for soldering. Specifically, when a copper or copper alloy material is used as the lead frame pattern 10, Ni of the substrate layer suppresses diffusion of copper, Au of a noble metal is used for the bonding surface, and Pd having good characteristics and being cheaper than Au is sandwiched. Between Ni and Au, it becomes an external connection terminal excellent in quality and cost. Accordingly, the plating layer 20 constituting the external connection terminal may be set so as to use a plating layer suitable for soldering as described above.

Further, the plating layer 20 is preferably suitable for welding. However, as long as it is made of a weldable material, its function and function can be sufficiently exerted, so that various materials can be selected within the range that can be welded.

The other components are the same as those of the lead frame 50 of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and their description is omitted.

4 is a view showing a series of steps of an example of a method of manufacturing a lead frame according to a second embodiment of the present invention.

Fig. 4 (a) is a view showing an example of a preparation step of a metal plate. This step is the same as the step explained in FIG. 2(a), and therefore the description thereof will be omitted.

Fig. 4 (b) is a view showing an example of a lead frame pattern forming step. This step The same steps are the same as those described in FIG. 2(b), and therefore the description thereof will be omitted.

Fig. 4 (c) is a view showing an example of a first plating layer forming step. In the first plating layer forming step, the first plating layer 20 is formed on the entire surface of the lead frame pattern 10. The formation of the first plating layer 20 can be carried out by a general plating treatment which is immersed in a plating solution and energized. In this regard, it is the same as that explained in Fig. 2(d). On the entire surface of the lead frame pattern 10, since there is no mask, the first plating layer 20 is formed on the entire surface.

Further, since the first plating layer 20 is used as an external connection terminal, it is formed of a weldable plating material, and is preferably made of a plating material suitable for welding. The palladium plating layer formed by sequentially laminating the above Ni, Pd, and Au from the lower layer is also suitable as an external connection terminal. Therefore, the palladium plating layer may be used as the first plating layer 20. Further, in the case of forming a palladium plating layer, first, the lead frame pattern 10 is immersed in a plating solution of Ni and electroplating is performed, and then, the lead pattern 10 to which Ni plating has been applied is immersed in the plating solution of Pd and Electroplating is performed, and finally, the lead frame pattern 10 to which Ni and Pd have been applied is immersed in the plating solution of Au and electroplated. It suffices to pass through the three plating tanks in order, so that the palladium plating layer can be easily formed.

Fig. 4 (d) is a view showing an example of a film attaching step. In this step, the object to which the film 40 is attached is the same as the lead frame pattern 10 in which the first plating layer 20 is formed on the entire surface, and is also the same as the step described in FIG. 2(c), and thus the description thereof will be omitted.

Fig. 4 (e) is a view showing an example of a second plating step. The second plating step is the same as the step described in FIG. 2(d) except that the object to which the second plating treatment is applied is the lead frame pattern 10 covering the entire surface with the first plating layer 20, As long as the same plating treatment can be performed. Accordingly, the description thereof will be omitted.

According to the lead frame of the second embodiment and the method of manufacturing the same, In a plating step, the entire surface of the lead frame pattern 10 is plated, and an arbitrary plating layer is formed on the surface of the external connection terminal, and a suitable external connection terminal can be formed according to the use.

FIG. 5 is a view showing an example of a surface mount type semiconductor package using the lead frame 51 of the second embodiment.

In FIG. 5, a surface-mounted semiconductor package in which the semiconductor element 60 is mounted on the semiconductor element mounting region 11 and the semiconductor 70 is used in the state in which the thin film 40 has been attached to the lead frame pattern 10 is shown. The terminal 61 of the element 60 is wire-bonded to the upper surface of the terminal region 12 and sealed with a resin 80. In this manner, the lead frame 51 can be shipped without peeling off the film 40, and the resin can be sealed in a state in which the film 40 is attached. By using a material having a material that does not cause the resin 80 to flow out, the film 40 can be easily packaged.

Further, since the upper surface (surface) and the side surface of the terminal region 12 are covered with the second plating layer 30 made of a material such as Ag suitable for wire bonding, wire bonding for connecting the lead 70 to the upper surface of the terminal region 12 can be suitably performed. .

After the resin is sealed, the film 40 is peeled off, and the back surface of the terminal region 12 is exposed to function as an external connection terminal on which the first plating layer 20 is formed. Since the first plating layer 20 is made of a material suitable for external connection, external connection can also be suitably performed.

In the lead frame 51 of the second embodiment, the film 40 can be easily resin-sealed directly on the film 40 where the resin 80 does not flow out in a state where the film 40 is attached to the lead frame 51. On the one hand, the advantages are also great.

In addition, although the lead frame 51 of the second embodiment is described as an example in FIG. 5, the lead frame 50 of the first embodiment can be easily resin-sealed in the same manner.

Figure 6 is a view showing lead frames 50 and 51 of the first and second embodiments of the present invention. A diagram of an example of a shipping method. As shown in FIG. 6, in the state in which the lead frames 50 and 51 are formed in the metal plate 15, the lead frames 50 and 51 of this embodiment can be shipped. With respect to the formation of the lead frame pattern 10 including the semiconductor element mounting region 11, the terminal region 12, and the like, one lead frame pattern 10 can be formed in one frame in the metal plate 15, and the lead frame pattern 10 is not completely removed from the frame. It is carried out in a state of being cut and connected and supported by the frame. Further, by performing the attaching and plating steps of the film 40 together, the plurality of lead frames 50 and 51 can be collectively manufactured.

Further, when the package of the lead frames 50 and 51 is packaged as shown in FIG. 5, the film 40 is peeled off, and finally the frame is cut and the packages are individually formed. The manufacture of the lead frames 50 and 51 and the manufacture of the surface mount type semiconductor package are performed.

As described above, the lead frame and the method of manufacturing the same according to the embodiment of the present invention can be mass-produced as appropriate, and high-efficiency mass production can be realized.

Hereinafter, an embodiment of a lead frame and a method of manufacturing the same according to an embodiment of the present invention will be described.

[Example 1]

As a metal plate 1 for a lead frame, a strip-shaped copper material (KLF-194 manufactured by Kobe Steel Co., Ltd.) having a thickness of 0.2 mm and a width of 180 mm was used, and a photosensitive resist having a thickness of 20 μm was formed on both surfaces of the metal plate 1. Layer (made by Asahi Kasei E-materials Co., Ltd.: negative photosensitive resist AQ-2058).

Then, exposure was performed using a glass mask (manufactured by Konica Minolta Advanced Layers Co., Ltd.: HY2-50P) in which the lead frame pattern was applied, and then a lead frame bare material was formed by development, etching, and peeling of the photosensitive resist. Then, an extremely thin plating layer of Ni, Pd, and Au is sequentially formed on the entire surface of the front and back surfaces. The thickness of the Ni film at this time is 0.6 μm, and the thickness of the Pd film is 0.015 μm. The Au film thickness was 0.0065 μm.

Then, a polyimide film (manufactured by Innox) was attached to the back surface, and an extremely smooth Ag plating layer (high cyanide Ag plating) having a thickness of 2.5 μm and a gloss of 1.7 GAM was further formed on the surface. As a result, a lead frame having different metal plating layers on the front and back surfaces was obtained. Then, the polyimine-based film strip on the back side is peeled off and the attached film is removed, and the sheet is cut in a strip shape, and is placed in an assembly step of the LED device, and the surface is Ag-plated, and the back surface is completed. It is an Ag/Ni/Pd/Au coated LED device.

[Example 2]

On the back surface of the lead frame bare material formed in the same manner as in the first embodiment, a polyimide film tape (manufactured by Tosawa Paper Co., Ltd.) was attached, and Ni, Pd, and Au were sequentially applied. Then, it is assembled in the semiconductor assembly step, and after the mold is sealed, the back polyimide-based film strip is peeled off. In this state, Cu was exposed on the back side, and Sn plating was applied to the Cu surface to form an exterior plating, and the lead frame of Example 2 was obtained.

[Example 3]

On the back surface of the lead frame bare material formed in the same manner as in Example 1, a polyimide film (manufactured by Nitto Dani Co., Ltd.) was attached, and Ni plating (sulfamic acid Ni) having a thickness of 0.8 μm was applied. Plating). On top of this, an underlayer of Ag (a Silveron GT-820 Strike manufactured by Dow Chemical Co., Ltd.) having a thickness of 0.05 μm was applied, and an Ag/Sn alloy plating having a thickness of 1.2 μm was further applied (Silveron GT-820 Cyanide manufactured by Dow Chemical- Free AgSn Plating). Then, it is assembled in the semiconductor assembly step, and after the mold is sealed, the back polyimide-based film strip is peeled off. In this state, Cu was exposed on the back side, and Sn plating was applied to the Cu surface to form an exterior plating, and the lead frame of Example 3 was obtained.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described above, and various modifications and substitutions may be made to the above-described embodiments without departing from the scope of the invention.

10‧‧‧ lead frame pattern

11‧‧‧Semiconductor component mounting area

12‧‧‧Terminal area

20, 30‧‧‧ plating

40‧‧‧ film

51‧‧‧ lead frame

60‧‧‧Semiconductor components

61‧‧‧ terminals

70‧‧‧ lead

80‧‧‧Resin

Claims (17)

A lead frame formed of a metal plate, at least a part of which is exposed as an external connection terminal, and a semiconductor element is mounted on the surface, so that a component as a surface mount type semiconductor package can be used; and the surface and the side surface are formed There is a plating layer for bonding which can be bonded to the semiconductor element, and a film is attached to the back surface. The lead frame of claim 1, wherein the back surface is an exposed surface on which the metal plate is exposed, and the film is attached to the exposed surface. The lead frame of claim 1, wherein an outer connection plating layer that can be electrically connected to the outside as the external connection terminal is formed on the entire surface of the metal plate, and the bonding plating layer is formed on the lead frame The external connection is on the plating. The lead frame of claim 3, wherein the external connection plating layer is formed on the back surface, and the thin film is attached to the external connection plating layer. The lead frame according to any one of claims 1 to 4, wherein the bonding plating layer is an Ag plating layer. The lead frame according to any one of claims 1 to 5, wherein the external connection plating layer is formed of a plating layer formed by sequentially laminating Ni, Pd, and Au from the lower layer. The lead frame of any one of claims 1 to 6, wherein the film is a film having an adhesive layer or an adhesive layer. The lead frame according to any one of claims 1 to 7, wherein the film can be used as a mask for electroplating, and is capable of preventing resin from flowing out when the resin is sealed, and can be used as The material of the mask exposed by the external connection terminals is formed. The lead frame of any one of claims 1 to 8, wherein the film is a film composed of polyimide. The lead frame of any one of claims 1 to 9, wherein the metal plate is made of a copper material or a copper alloy material. A method of manufacturing a lead frame, wherein the lead frame is exposed to an external connection terminal on a back surface, and is used for a surface mount type semiconductor package in which a semiconductor element is mounted on a surface; the method of manufacturing the lead frame has: processing a metal plate a step of forming a lead frame pattern; a step of attaching a film to the back surface of the lead frame pattern; and a step of forming a plating layer on the surface and the side surface of the lead frame by using the film as a mask. The method of manufacturing a lead frame according to claim 11, wherein the film is a strip-shaped film having an adhesive layer or an adhesive layer, and the film is attached to the lead frame by using the adhesive layer or the adhesive layer. The back side of the pattern. The method of manufacturing a lead frame according to claim 11 or 12, wherein the step of forming a plating layer comprises the step of plating Ag on the lead frame pattern. A method of manufacturing a lead frame, wherein the lead frame is exposed to an external connection terminal on a back surface, and is used for a surface mount type semiconductor package in which a semiconductor element is mounted on a surface; the method of manufacturing the lead frame has: processing a metal plate a step of forming a lead frame pattern; a step of forming a first plating layer on the entire surface of the lead frame pattern; a step of attaching a film on a back surface of the lead frame pattern; and using the film as a mask on the lead frame The step of forming a second plating layer on the surface and the side surface. The method of manufacturing a lead frame according to claim 14, wherein the film is a strip-shaped film having an adhesive layer or an adhesive layer, and the film is attached to the lead frame by using the adhesive layer or the adhesive layer. The back side of the pattern. The method of manufacturing a lead frame according to claim 14 or 15, wherein the first plating layer is a plating layer formed by sequentially laminating Ni, Pd, and Au from the lower layer, and the step of forming the first plating layer includes Ni, Pd, and Au are sequentially plated on the lead frame pattern. The method of manufacturing a lead frame according to any one of claims 14 to 16, wherein the step of forming the second plating layer comprises the step of plating Ag on the lead frame pattern.