JP2021120992A - Lead frame - Google Patents

Abstract

To provide a lead frame which can maximize the area of a side face opening in the form of a port for allowing a soldering connection of a semiconductor package product to be observed visually, and which can prevent the deformation owing to the decrease in lead strength.SOLUTION: A lead frame comprises: a thin part 11-1a formed by a concave form of a depth representing 75-90% of a thickness of a copper-based metal plate 10 on one side in a first region 11-1 extending beyond boundary lines L a cutting region for cutting into individual packages and including part of a region making an external connection terminal of a lead 11 formed by the metal plate; a reinforcement-plating layer 14 of a concave form formed on a surface of the thin part so as to have a thickness equal to or larger than 7.5% of the thickness of the metal plate; and a plating layer 12 for external connection formed in a surface of a second region 11-2 including the first region where the reinforcement-plating layer is formed. A surface of the plating layer for external connection at a position of the boundary line L of the lead cutting region in a bottom of the concave form is located at a depth substantially equal to or larger than 50% of the metal plate thickness from one side of the metal plate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lead frame used for manufacturing a semiconductor package of a type in which an external connection terminal on the back surface side is connected to an external device such as a printed circuit board.

When incorporating a semiconductor package into an external device, visualization of the solder connection portion is required so that the quality or defect of the solder connection state between the semiconductor package and the external device can be visually inspected.

Conventionally, in a QFN (Quad-Flat No-leaded) type semiconductor package having no outer lead on the outer periphery, external connection terminals are arranged on the back side of the semiconductor package and exposed on the back side of the semiconductor package. Since the structure is such that a plurality of external connection terminals are connected to an external device such as a printed circuit board, it is difficult to visually inspect whether or not they are solder-connected.

However, if the solder connection portion cannot be visually inspected, the connection failure inherent in the solder connection work is overlooked, and the work cost until the connection failure is found in the subsequent energization inspection or the like is incurred. Further, although it is possible to perform a fluoroscopic inspection of the solder connection portion using an X-ray apparatus, that would increase the equipment cost of the X-ray apparatus.

Therefore, conventionally, as a technique for visually inspecting the good or bad of the solder connection state in the solder connection portion of the QFN type semiconductor package, Patent Document 1 describes one surface side (back surface) of the lead in the lead frame. By forming a groove across the lead at the cutting position of the terminal part that will be the external connection terminal on the side), the edge part of the external connection terminal that is exposed on the back surface of the semiconductor package when individually cut. It has been proposed that a space portion is provided so that the solder is interposed in the space portion so that the solder connection portion can be visually recognized from the external connection terminal exposed on the side surface of the semiconductor package.

Further, in Patent Document 2, a recess is provided inside a predetermined region straddling the boundary line of the cutting region, including a region serving as an external connection terminal for the lead on one side surface (back surface) of the lead frame, and the front surface side. After sealing with resin, the surface of the recess is cut at a position where it can be exposed so that the exposed side surface of the external connection terminal becomes a gate shape, and from the external connection terminal exposed on the side surface of the semiconductor package. A technique for making the solder connection portion visible is disclosed.

Japanese Unexamined Patent Publication No. 2000-294715 Japanese Unexamined Patent Publication No. 2018-20094

However, in the technique of forming a groove crossing a lead described in Patent Document 1, the resin enters the groove at the time of resin sealing, and a space portion for making the solder connection portion visible is not formed, and the semiconductor package. There is a risk that the product yield will deteriorate.

Regarding this point, according to the technique described in Patent Document 2 in which the side surface of the external connection terminal has a gate shape, a space portion that makes the solder connection portion visible can be obtained. It is desired to further expand the opening area of the side surface to make the solder connection portion as easy to see as possible.

In order to facilitate visual inspection of the solder connection portion, if the opening area of the side surface of the lead frame having the configuration as described in Patent Document 2 which is the gate shape of the external connection terminal is increased as much as possible, the lead is partially formed. Since the wall thickness is thin, the strength is insufficient and there is a risk of deformation in the semiconductor package assembly process.

The present invention has been made in view of the above-mentioned conventional problems, and at the same time, the opening area of the side surface of the semiconductor package product having a gate shape, which is a portion where the solder connection portion is visible, is increased as much as possible, and at the same time, the lead It is an object of the present invention to provide a lead frame capable of preventing deformation due to a decrease in strength.

In order to achieve the above object, the lead frame according to the present invention is a lead frame used for a semiconductor package in which external connection terminals are exposed on one side surface and a side surface, and is formed of a metal plate made of a copper-based material. In the first region of the lead, which includes a part of the region serving as the external connection terminal and straddles the boundary line of the cutting region for cutting into individual packages, the metal plate on one surface side. It has a thin-walled portion formed by a recess having a depth of 75 to 90% of the plate thickness, and a concave reinforcing plating layer is formed on the surface of the thin-walled portion by 7.5% or more of the plate thickness of the metal plate. An external connection plating layer is formed on the surface on one side of the second region including the first region formed with a thickness and the reinforcing plating layer is formed, and the lead is said to have a thickness. The surface of the external connection plating layer at the position of the concave bottom of the boundary line of the cutting region is located at a depth of about 50% or more of the plate thickness of the metal plate from one surface side of the metal plate. It is a feature.

Further, in the lead frame of the present invention, the reinforcing plating layer is a plating layer containing nickel, and the thickness of the plating layer at the portion where the reinforcing plating layer and the external connection plating layer are laminated is determined. It is preferably 10% or more of the plate thickness of the metal plate. Its thickness is realistically in the range of approximately 5 to 55 μm.

Further, in the lead frame of the present invention, it is preferable that the side surface of the lead has a portion where the reinforcing plating layer is exposed from the metal plate.

Further, in the lead frame of the present invention, it is preferable that the reinforcing plating layer is exposed on the side surface of the lead at the position of the boundary line of the cutting region.

According to the present invention, it is possible to increase the opening area of the side surface of the semiconductor package product having a gate shape, which is a portion where the solder connection portion is visible, as much as possible, and at the same time, prevent deformation due to a decrease in lead strength. A lead frame is obtained.

It is explanatory drawing which shows the main part structure of the lead frame which concerns on 1st Embodiment of this invention, (a) is the figure which was seen from one side (the side which connects with an external device), (b) is (a) Viewed from the opposite side, (c) is a cross-sectional view of AA of the region serving as an external connection terminal in the lead frame of (a), (c') is a partially enlarged view of (c), and (d) is (a). ) Is a cross-sectional view taken along the line BB of the region serving as an external connection terminal in the lead frame, (e) is a view seen from the side connected to an external device showing a modified example, and (f) is a cross-sectional view taken along the line CC of (e). Is. It is explanatory drawing which shows an example of the manufacturing procedure of the lead frame of FIG. 1 in the AA cross section of FIG. 1 (a). It is explanatory drawing which shows an example of the manufacturing procedure of the lead frame of FIG. 1 in the BB cross section of FIG. 1 (a). It is explanatory drawing which shows an example of the manufacturing procedure of the package using the lead frame manufactured by the manufacturing procedure of FIG. 2 and FIG. It is a side view seen from the same side as FIG. 4 (e) which shows the state in which the external connection terminal of the semiconductor package manufactured by the manufacturing procedure of FIG. 4 is solder-connected to an external device.

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

First Embodiment As shown in FIG. 1, the lead frame 1 of the first embodiment is a part of a region serving as an external connection terminal on one surface side of a lead 11 formed of a metal plate made of a copper-based material. A thin portion 11-1a is provided in a region 11-1 that includes, and crosses the boundary line L of the cutting region for cutting into individual packages and intersects the dam bar 13.
As shown in FIGS. 1 (c) and 1 (c'), the thin portion 11-1a is formed by a recess having a depth of 75 to 90% of the plate thickness of the metal plate 10 on one surface side. ..
Further, on the surface (inner surface) of the thin portion 11-1a, a concave reinforcing plating layer 14 made of a plating layer containing nickel has a thickness of 7.5% or more of the plate thickness of the metal plate 10. It is formed.
Further, an external connection plating layer 12 is formed on the surface on one surface side of the second region 11-2 including the first region 11-1 on which the reinforcing plating layer 14 is formed.
The thickness of the plating layer at the portion where the reinforcing plating layer 14 and the external connection plating layer 12 are laminated has 10% or more of the plate thickness of the metal plate 10.
Further, the surface of the external connection plating layer 12 at the position of the concave bottom of the boundary line L of the cutting region of the lead 11 is approximately 50% or more of the plate thickness of the metal plate 10 from one surface side of the metal plate 10. It is located at the depth of.
The external connection plating layer 12 is preferably composed of a plating layer in which nickel, palladium, and gold are laminated in this order.
Further, as shown in FIG. 1 (d), the thin-walled portion 11-1a has a concave shape such that the BB cross section of FIG. 1 (a) has a gate shape, as well as FIG. 1 ( As shown in e) and FIG. 1 (f), the reinforcing plating layer 14 may be formed only on the other side of the lead 11 and the reinforcing plating layer 14 may be exposed on the side surface of the lead 11.

Next, an example of the manufacturing process of the lead frame of the present embodiment shown in FIG. 1 will be described with reference to FIGS. 2 and 3.
First, a metal plate 10 made of a copper-based material is prepared (see FIGS. 2 (a) and 3 (a)).
Next, the metal plate 10 is half-etched to form the recess 11-1b.
Specifically, a first resist layer R1 such as a dry film resist is formed on both surfaces of the metal plate 10 (see FIGS. 2 (b) and 3 (b)). Next, the entire surface of the first resist layer R1 on the other surface side of the metal plate 10 is exposed, and the first resist layer on the one surface side of the metal plate 10 is used by using a glass mask on which a predetermined pattern is drawn. R1 is exposed and developed to form a resist mask 31 for both etching and plating, which has an opening in a portion corresponding to the thin-walled portion 11-1a and covers the other portion (FIGS. 2 (c) and 3 (FIG. 3). c)). Next, half-etching is performed from one surface side of the metal plate 10 to a depth of 75 to 90% of the plate thickness of the metal plate 10 using an etching solution, and the recess 11-1b is applied to one surface side of the metal plate 10. (See FIG. 2 (d) and FIG. 3 (d)). The width of the inner surface of the recess 11-1b is formed to be 50 to 100% of the width of the lead 11 depending on the width of the lead 11. When the width of the inner surface of the recess 11-1b is formed to be 100% (or 100% or more) of the lead 11, the reinforcing plating layer is exposed on the side surface of the lead 11 when the lead frame shape is formed in the subsequent process. Can be done.
Next, from one surface side of the metal plate 10, the surface (inner surface) of the recess 11-1b is plated with nickel or a nickel alloy having a thickness of 7.5% or more of the thickness of the metal plate 10 to form a concave shape. (See FIGS. 2 (e) and 3 (e)). Then, the etching / plating resist mask 31 formed on the metal plate 10 is removed (see FIGS. 2 (f) and 3 (f)).

Next, three types of steps for forming the plating layer for internal connection and the plating layer for external connection will be briefly described.
First, in the case of a lead frame in which a plating layer of the same material is required for the plating layer for internal connection and the plating layer for external connection, a resist mask in which the portion forming the plating layer is open is formed on both sides and plating is performed. .. For example, nickel, palladium, and gold are plated in this order, and then the resist masks on both sides are removed.
Further, in the case of a lead frame in which a plating layer made of a different material is required for the internal connection plating layer and the external connection plating layer, a resist mask is formed on the other surface side in which the portion forming the internal connection plating layer is open. Then, a resist mask covering the entire surface is formed on one side, and plating is performed. For example, silver plating is applied to form a plating layer for internal connection, and then the resist masks on both sides are removed. Next, a resist mask covering the entire surface is formed on the other surface side, and a resist mask in which the portion forming the plating layer for external connection is open is formed on one surface side and plated, for example, nickel. Plating is performed in the order of palladium and gold, and then the resist masks on both sides are removed.
In the case of a lead frame in which only the external connection plating layer is required without forming the internal connection plating layer, a resist mask covering the entire surface is formed on the other surface side, and the external connection plating is formed on one surface side. A resist mask in which the portion forming the layer is open is formed and plated, for example, nickel, palladium, and gold are plated in this order, and then the resist masks on both sides are removed.

Here, the steps of forming the plating layer for external connection will be described again with reference to FIGS. 2 and 3.
A second resist layer R2 such as a dry film resist is formed on both surfaces of the metal plate 10 (see FIGS. 2 (g) and 3 (g)). Next, the second resist layer R2 on the other surface side exposes the entire surface, and the second resist layer R2 on the one surface side is exposed using a glass mask on which a predetermined pattern is drawn, developed, and read. A portion corresponding to the second region 11-2 of 11 is opened to form a resist mask 32 for plating that covers the other portions (see FIGS. 2 (h) and 3 (h)).
Next, the portion exposed from the resist mask 32 for plating is plated in the order of, for example, nickel, palladium, and gold (see FIGS. 2 (i) and 3 (i)). As a result, the external connection plating layer 12 is formed on the surface of one side of the second region 11-2 including the first region where the concave reinforcing plating layer 14 is formed.
When forming the external connection plating layer 12, the surface of the external connection plating layer 12 at the position of the concave bottom of the boundary line L of the cutting region of the lead 11 is made of metal from one surface side of the metal plate 10. The plating thickness is adjusted so that it is located at a depth of approximately 50% or more of the plate thickness of the plate 10.
At this time, it is preferable that the combined thickness of the reinforcing plating layer 14 and the external connection plating layer 12 is 10% or more of the plate thickness of the metal plate 10. Its thickness is realistically in the range of approximately 5 to 55 μm.
Further, the surface of the external connection plating layer 12 may be formed as a roughened surface. When forming a roughened surface, for example, the nickel plating layer of the external connection plating layer 12 may be formed by roughening plating. Further, for example, after forming a smooth nickel plating layer, a roughened surface may be formed by etching the surface of the nickel plating layer. Further, the plating layer may be laminated in the order of palladium and gold on the nickel plating layer on which the roughened surface is formed.
After that, the resist mask 32 for plating on both sides is removed (see FIGS. 2 (j) and 3 (j)).

Next, the metal plate 10 is etched to form a lead frame shape.
Specifically, a third resist layer R3 such as a dry film resist is formed on both sides of the metal plate 10 (see FIG. 3 (k)). Next, the third resist layer R3 on the other side of the metal plate 10 and the third resist layer R3 on the other side of the metal plate 10 are formed by using a glass mask on which a predetermined pattern necessary for obtaining the lead frame shape is drawn. It is exposed and developed to form an etching resist mask 33 on both surfaces of the metal plate 10 (see FIG. 3 (l)).
Next, etching processing is performed from both surface sides of the metal plate 10 using an etching solution, and the regions of the individual lead frames are multi-row lead frames connected to the dam bar 13 and cut into individual semiconductor packages. A lead frame is formed in which the cross-sectional shape of the terminal portion serving as the terminal for external connection at the time is a gate shape (see FIG. 3 (m)).
Next, the etching resist mask 33 is removed (see FIG. 3 (n)).
As a result, the lead frame 1 of the present embodiment is completed.
When the lead frame 1 is formed by performing the etching process, the intermediate portion of the lead and other necessary parts may be half-etched.

Next, the manufacturing procedure of the semiconductor device using the lead frame of the present embodiment will be briefly described with reference to FIGS. 4 and 5.
A semiconductor element is mounted on the other surface side of the lead frame of the present embodiment, and the electrodes of the semiconductor element and a predetermined internal connection terminal are wire-bonded or flip-chip mounted (not shown).
Next, a sheet-shaped masking tape m1 is attached to one surface side (see FIG. 4A), a mold mold (not shown) is set, and the semiconductor element mounting side is sealed with resin 21 (FIG. 4 (Fig. 4). b)) At this time, in the concave portion formed by laminating the reinforcing plating layer 14 and the external connection plating layer 12, the end face on one side is in close contact with the masking tape m1 and the inside is sealed. It becomes a state. Therefore, when the sealing resin is formed, the resin 21 does not penetrate into the concave portion formed by laminating the reinforcing plating layer 14 and the external connection plating layer 12.
Next, the masking tape m1 is removed (see FIG. 4 (c)) and cut to the dimensions of the predetermined semiconductor device 40 (see FIGS. 4 (d) and 4 (d')). As a result, the semiconductor device 40 using the lead frame of the present embodiment is completed (see FIG. 4 (e)).
When the external connection terminal of the semiconductor package 40 using the lead frame 1 of the present embodiment obtained in this manner is solder-connected to the terminal 81 of the printed circuit board 80, the solder 90 is exposed to the external connection on the side surface of the semiconductor package 40. The solder connection portion can be visually confirmed from the gate-shaped opening of the terminal, and the quality and defect of the connection state can be visually inspected (see FIG. 5).

According to the lead frame 1 of the present embodiment, the solder connection portion when the semiconductor package is solder-connected to an external device can be visually confirmed from the side surface, and the thickness is 7.5% or more of the plate thickness of the metal plate 10. By forming the reinforcing plating layer 14 in the above, even if the opening area of the gate shape is made larger (wider) than in the conventional case, the strength of the lead 11 is not lowered and the deformation that occurs in the manufacturing process of the semiconductor package can be prevented. When the cutting process is performed by the blade at the boundary line L of the cutting region, the cut surface to be the side surface of the semiconductor package has a large gate-shaped opening area, so that the amount of copper-based material is reduced. It is possible to reduce the burrs caused by the copper-based material in the external connection terminal exposed on the side surface of the semiconductor package, which has been conventionally generated.
Further, when the width of the inner surface of the recess 11-1b formed by the above-mentioned half-etching process is formed to be the width (100%) of the lead 10, the cut surface to be the side surface of the semiconductor package is most of the side surface of the lead 11. Becomes a reinforcing plating layer and a plating layer for external connection, and the copper-based material existing on the side surface is significantly reduced (only the side surface of the copper-based material existing on the other surface side), so that burrs are generated by the copper-based material. It can be further suppressed.
As a result, the productivity of the process of cutting individual semiconductor packages with blades is also improved.

Example 1
First, a copper-based material having a thickness of 0.2 mm was prepared as the metal plate 10 (see FIGS. 2 (a) and 3 (a)), and a dry film resist was laminated on both sides as the first resist layer R1 (see FIGS. 2 (a) and 3 (a)). See FIGS. 2 (b) and 3 (b)).
Next, exposure and development are performed to form a resist mask 31 for both etching and plating that covers the entire surface on the other surface side (front surface side), and the lead frame shown in FIG. 1 is formed on one surface side (back surface side). A resist mask 31 for both etching and plating was formed by having an opening in a portion corresponding to the thin-walled portion 11-1a in the above (see FIGS. 2 (c) and 3 (c)).
Next, a half etching process was performed using an etching solution to form a recess 11-1b on one surface side of the metal plate 10 (see FIGS. 2 (d) and 3 (d)). As a condition of the half-etching process, the recess 11-1b is 85% deep in the thickness of the metal plate 10 and 20% on both sides in the width direction of 60% of the width of the lead 11 (formed later). It was set to include a copper-based material with a width.
After forming the recess 11-1b on one surface side of the metal plate 10, plating is performed using the same etching / plating resist mask 31, and the recess 11-1b (inner surface) is nickel-plated with a set thickness of 19 μm. A concave reinforcing plating layer 14 having an opening on one surface side was formed (see FIGS. 2 (e) and 3 (e)).
Then, the resist mask 31 for both etching and plating on both sides was removed (see FIGS. 2 (f) and 3 (f)).

Next, a dry film resist was laminated on both sides of the copper-based metal plate 10 as a second resist layer R2 (see FIGS. 2 (g) and 3 (g)).
Then, exposure / development is performed using a glass mask on which a predetermined pattern is drawn, and a portion corresponding to a region (not shown) serving as an internal connection terminal is opened on the other surface side, and other portions are formed. A portion corresponding to a second region 11-2 including a first region 11-1 in which a covering resist mask 32 for plating is formed and a concave reinforcing plating layer 14 is formed on one surface side. Was opened to form a resist mask 32 for plating covering the other portions (see FIGS. 2 (h) and 3 (h)).
Next, plating is performed, and nickel plating with a set thickness of 1 μm, palladium plating with a set thickness of 0.01 μm, and gold plating with a set thickness of 0.001 μm are performed in this order to form an area that becomes an internal connection terminal for the lead 11. An internal connection plating layer (not shown) was formed on the surface (not shown), and an external connection plating layer 12 was formed on the surface of the second region 11-2 (FIGS. 2 (i) and 3 (FIG. 3). i)). The external connection plating layer 12 is laminated on the concave reinforcing plating layer 14 formed earlier by this plating process.
Then, the resist masks 32 on both sides were removed (see FIGS. 2 (j) and 3 (j)).

Next, a dry film resist was laminated on both sides of the metal plate 10 as a third resist layer R3 (see FIG. 3 (k)).
Next, after exposure and development, the other surface side is a part that becomes a predetermined lead frame including a part where nickel, palladium, and gold plating, which are terminals for internal connection, are laminated in order, and a part that becomes a dam bar. The etching resist mask 33 is formed by covering the surface and exposing the other parts, and one surface side thereof includes a portion in which nickel, palladium, and gold plating, which are terminals for external connection, are laminated in this order. An etching resist mask 33 was formed by covering a portion to be a lead frame and exposing other portions (see FIG. 3 (l)).
Next, etching processing was performed to form a predetermined lead frame and dam bar shape from the metal plate 10 (see FIG. 3 (m)).
Then, the resist masks 33 on both sides were removed (see FIG. 3 (n)).
In this way, the other surface side is provided with the internal connection terminal, the one surface side is provided with the external connection terminal, and the boundary line L of the cutting region for cutting into individual packages of the leads 11 connected to the dam bar 13. Example 1 in which a portion straddling the metal plate 10 is formed of a metal plate 10, a reinforcing plating layer 14 and an external connection plating layer 12, and a concave opening is provided inside the external connection plating layer 12 on one surface side. I got the lead frame of.
It was confirmed that the lead frame of Example 1 obtained had no deformation of the lead 11 having a concave opening.

Example 2
The process from the preparation of the metal plate 10 to the formation of the resist mask 31 for both etching and plating is performed in substantially the same manner as in Example 1, but the width of the inner surface of the recess 11-1b formed on one surface side of the metal plate 10 is set to the width of the lead 11. A resist mask 31 for both etching and plating was opened so as to have the same width as the width, and half-etching was performed at the same depth as in Example 1 to form a recess 11-1b on one surface side of the metal plate 10. By applying nickel plating having a set thickness of 15 μm, a concave reinforcing plating layer 14 having an opening on one side was formed.
Subsequent steps are carried out in the same manner as in the first embodiment, so that an internal connection terminal is provided on the other surface side, an external connection terminal is provided on one surface side, and individual packages of leads 11 connected to the dam bar 13 are provided. The portion that straddles the boundary line L of the cutting region for cutting is formed by the metal plate 10, the reinforcing plating layer 14, and the external connection plating layer 12 as in the first embodiment, but the metal plate 10 is on the other surface side. The lead frame of Example 2 in which the reinforcing plating layer 14 and the side surface of the metal plate 10 on the other surface side and the external connection plating layer 12 on one surface side were exposed was obtained.
It was confirmed that the lead frame of Example 2 obtained had no deformation of the lead 11 having a concave opening.

Comparative Example 1
After the process from the preparation of the metal plate 10 to the formation of the recess 11-1b on one surface side of the metal plate 10 is performed in the same manner as in Example 2, nickel plating having a set thickness of 11 μm is performed so that one surface side can be made. An open concave reinforcing plating layer 14 was formed.
Subsequent steps are carried out in the same manner as in the second embodiment, so that an internal connection terminal is provided on the other surface side, an external connection terminal is provided on one surface side, and individual packages of leads 11 connected to the dam bar 13 are provided. The portion that straddles the boundary line L of the cutting region for cutting is formed by the metal plate 10, the reinforcing plating layer 14, and the external connection plating layer 12 as in the first embodiment, but the metal plate 10 is on the other surface side. The lead frame of Comparative Example 1 in which the reinforcing plating layer 14 and the side surface of the metal plate 10 on the other surface side and the external connection plating layer 12 on one surface side were exposed was obtained.
In the obtained lead frame of Comparative Example 1, deformation was confirmed in several leads 11 having concave openings, and when the thickness of the reinforcing plating layer 14 was 6.5% of that of the metal plate 10, the strength was high. The result was that there was a shortage.

Comparative Example 2
The recess 11-1b is formed substantially in the same manner as in the first embodiment, but as a condition of the half-etching process, the recess 11-1b has a depth of 85% of the thickness of the metal plate 10 and the lead 11 (to be formed later). The width is 70% of the width of the above, and a copper-based material having a width of 15% is provided on both sides of the recess 11-1b in the width direction.
Then, the resist mask 31 for both etching and plating was removed without forming the reinforcing plating layer 14.
Subsequent steps are carried out in the same manner as in the first embodiment, so that the terminals for internal connection are provided on the other surface side, the terminals for external connection are provided on one surface side, and the individual packages of the leads 11 connected to the dam bar 13 are individually packaged. The portion that straddles the boundary line L of the cutting region for cutting is formed by the metal plate 10 and the plating layer 12 for external connection, with the metal plate 10 on the other surface side and the side surface and the metal plate 10 on one surface side. The lead frame of Comparative Example 2 in which the plating layer 12 for external connection was exposed was obtained.
In the obtained lead frame of Comparative Example 2, deformation was confirmed in several leads 11 having concave openings, and it was confirmed that the strength was insufficient.

Comparative Example 3
After forming the recess 11-1b in the same manner as in Example 1, the resist mask 31 for both etching and plating was removed without forming the reinforcing plating layer 14.
Subsequent steps are carried out in the same manner as in the first embodiment, so that the terminals for internal connection are provided on the other surface side, the terminals for external connection are provided on one surface side, and the individual packages of the leads 11 connected to the dam bar 13 are individually packaged. The portion that straddles the boundary line L of the cutting region for cutting is formed by the metal plate 10 and the plating layer 12 for external connection, with the metal plate 10 on the other surface side and the side surface and the metal plate 10 on one surface side. The lead frame of Comparative Example 3 in which the plating layer 12 for external connection was exposed was obtained.
In the obtained lead frame of Comparative Example 3, deformation was confirmed in several leads 11 having concave openings, and it was confirmed that the strength was insufficient.

1 Lead frame 10 Metal plate 11 Lead 11-1 First area 11-1a Thin-walled part 11-1b Recess 11-2 Second area 12 External connection plating layer 13 Dam bar 14 Reinforcing plating layer 21 Encapsulating resin 31 Etching Resist mask for plating 32 Resist mask for plating 33 Resist mask for etching 40 Semiconductor package 80 External device 81 Terminal 90 Solder m1 Masking tape R1 First resist layer R2 Second resist layer R3 Third resist layer

Claims (4)

A lead frame used for a semiconductor package in which external connection terminals are exposed on one side surface and side surface.
In the first region of the lead formed of a metal plate made of a copper-based material, which includes a part of the region serving as the external connection terminal and straddles the boundary line of the cutting region for cutting into individual packages. It has a thin portion formed by a recess having a depth of 75 to 90% of the plate thickness of the metal plate on one surface side.
A concave reinforcing plating layer is formed on the surface of the thin-walled portion so as to have a thickness of 7.5% or more of the thickness of the metal plate.
An external connection plating layer is formed on the surface on one side of the second region including the first region on which the reinforcing plating layer is formed.
The surface of the external connection plating layer at the position of the concave bottom of the boundary line of the cutting region of the lead is at a depth of about 50% or more of the plate thickness of the metal plate from one surface side of the metal plate. A lead frame characterized by being located. The reinforcing plating layer is a plating layer containing nickel.
The lead according to claim 1, wherein the thickness of the plating layer at the portion where the reinforcing plating layer and the external connection plating layer are laminated is 10% or more of the plate thickness of the metal plate. flame. The lead frame according to claim 1, wherein the side surface of the lead has a portion where the reinforcing plating layer is exposed from the metal plate. The lead frame according to claim 1, wherein the side surface of the lead at the position of the boundary line of the cutting region is exposed to the reinforcing plating layer.

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