JP7112663B2 - Manufacturing method of lead frame and semiconductor device - Google Patents

Description

The present invention relates to a lead frame and a method of manufacturing a semiconductor device.

In recent years, there has been a demand for miniaturization and thinning of semiconductor devices mounted on substrates. In order to meet such demands, conventionally, a lead frame is used, a semiconductor element mounted on the mounting surface thereof is sealed with a sealing resin, and a portion of the lead is exposed on the back side of the so-called QFN. Various (Quad Flat Non-lead) type semiconductor devices have been proposed.

Conventionally, in the process of manufacturing a QFN package, the lead frame is cut after resin sealing to separate the lead frame for each package. When cutting the leadframe in this way, the leadframe is cut by about half the thickness in the first sawing, and then a thinner blade than the blade used in the first sawing is used to cut the leadframe in the second sawing. is known to separate the lead frames from each other (see, for example, Patent Document 1).

U.S. Pat. No. 7,183,630

As described above, when a lead frame is cut by two sawing steps, the first sawing cuts the lead frame to a predetermined depth (for example, about half), and the second sawing separates the lead frame. These two sawings are both done along the connecting bar. For this reason, for example, if the connecting bar is distorted by the pressure of the molten resin during resin sealing, there is a problem that the shape of the lead portion and the like after sawing does not become the desired shape.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above points, and provides a method of manufacturing a lead frame and a semiconductor device capable of increasing the strength of the connecting bar and suppressing the distortion occurring in the connecting bar during sawing. With the goal.

According to the present invention, a lead frame includes a die pad, a lead portion provided around the die pad, and a connecting bar to which the lead portion is connected, wherein the width of the surface of the connecting bar is equal to the width of the back surface of the connecting bar. and the largest width portion of the connecting bar is located between the front surface and the rear surface of the connecting bar.

The present invention is the lead frame, wherein the maximum width portion is located closer to the front surface than an intermediate position between the front surface and the back surface of the connecting bar.

The present invention is a lead frame in which a recess is formed in at least one of the front surface and the back surface of the connecting bar.

In the present invention, the two connecting bars orthogonal to each other are connected to each other by a connection portion, the die pad and the connection portion are connected to each other by suspension leads, the connection portion is not thinned, and the suspension leads are connected to each other. is a lead frame thinned from the back side.

The present invention is the lead frame, wherein a portion of the lead portion that is connected to the connecting bar is tapered in a plan view.

The present invention is the lead frame, wherein notches are formed in portions of the connecting bar located on both sides of the lead portion.

In the present invention, the width of the surface of the connecting bar is wider than the width of the back surface of the connecting bar by 15 μm or more and 25 μm or less, and the width of the maximum width portion is 10 μm or more and 15 μm or less than the width of the surface of the connecting bar. Only wide is the lead frame.

The present invention provides a method for manufacturing a semiconductor device, comprising the steps of: preparing the lead frame; mounting a semiconductor element on the die pad of the lead frame; A step of sealing the die pad, the lead portion, the semiconductor element, and the connection member with a sealing resin, and along the connecting bar, the thickness of the lead frame from the back side A method of manufacturing a semiconductor device, comprising the steps of: removing a part in a direction; and cutting the lead frame and the sealing resin for each semiconductor device.

ADVANTAGE OF THE INVENTION According to this invention, the strength of a connecting bar can be improved and the distortion which arises in a connecting bar at the time of sawing can be suppressed.

1 is a plan view showing part of a lead frame according to an embodiment; FIG. FIG. 2 is a bottom view showing part of the lead frame according to one embodiment; FIG. 3 is a cross-sectional view (cross-sectional view taken along line III-III in FIG. 1) showing the lead frame according to one embodiment; FIG. 4 is an enlarged plan view showing a part of the lead frame according to one embodiment; FIG. 5 is a cross-sectional view showing a connecting bar (cross-sectional view taken along line VV in FIG. 4); FIG. 6 is a plan view showing a semiconductor device according to one embodiment; FIG. 7 is a cross-sectional view (cross-sectional view taken along line VII-VII in FIG. 6) showing the semiconductor device according to one embodiment; 8A to 8E are cross-sectional views showing a method of manufacturing a lead frame according to an embodiment; FIG. 9A to 9D are cross-sectional views showing the method (first half) for manufacturing the semiconductor device according to the embodiment; 10A to 10C are cross-sectional views showing the method (second half) for manufacturing the semiconductor device according to the embodiment; FIG. 11 is a cross-sectional view showing the connecting bar after step cutting; FIG. 12 is a plan view showing a part of a lead frame according to a modified example (modified example 1); FIG. 13 is a cross-sectional view showing a connecting bar according to a modified example (modified example 2); FIG. 14 is a cross-sectional view showing a connecting bar according to a modified example (modified example 3); FIG. 15 is a cross-sectional view showing a connecting bar according to a modified example (modified example 4); FIG. 16 is an enlarged plan view showing a part of a lead frame according to a modified example (modified example 5); FIG. 17 is an enlarged plan view showing a part of a lead frame according to a modified example (modified example 6);

An embodiment will be described below with reference to FIGS. 1 to 11. FIG. In addition, in each figure below, the same reference numerals are assigned to the same parts, and some detailed explanations may be omitted.

Structure of Lead Frame First, the outline of the lead frame according to the present embodiment will be described with reference to FIGS. 1 to 5. FIG. FIG. 1 is a plan view showing part of the lead frame according to the present embodiment, FIG. 2 is a bottom view showing part of the lead frame according to the present embodiment, and FIG. 3 is the present embodiment. 1 is a cross-sectional view showing a lead frame according to FIG. 4 is an enlarged plan view showing a part of the lead frame according to this embodiment, and FIG. 5 is a sectional view showing a connecting bar.

A lead frame 10 shown in FIGS. 1 to 3 is used when manufacturing a semiconductor device 20 (FIGS. 6 and 7). Such a lead frame 10 includes an outer peripheral region 18 having a rectangular outer shape and a plurality of package regions 10a arranged in multiple rows and multiple stages (in a matrix) within the outer peripheral region 18 . 1 and 2, only a part including the corners of the lead frame 10 is shown.

The outer peripheral region 18 is formed in a rectangular annular shape in plan view so as to surround the plurality of package regions 10a. The width W1 of the outer peripheral region 18 may be 2 mm or more and 10 mm or less. Note that the peripheral region 18 has the same thickness as the metal substrate (metal substrate 31 described later) before processing without being thinned (half-etched).

Here, half-etching means etching the material to be etched halfway in its thickness direction. The thickness of the material to be etched after half-etching is, for example, 30% or more and 70% or less, preferably 40% or more and 60% or less of the thickness of the material to be etched before half-etching. In each figure, half-etched regions are indicated by shading.

In this specification, the terms “inner” and “inner” refer to the side of each package region 10a facing the center of the die pad 11, and the terms “outer” and “outer” refer to the center of the die pad 11 in each package region 10a. It refers to the side (connecting bar 13 side) away from. Further, the “front surface” refers to the surface on which the semiconductor element 21 is mounted, and the “back surface” refers to the surface opposite to the “front surface” and connected to an external mounting substrate (not shown). say the face

As shown in FIGS. 1 to 3, each package region 10a includes a planar rectangular die pad 11 on which a semiconductor element 21 (described later) is mounted, and a die pad 11 surrounding the semiconductor element 21 and an external circuit (not shown). ) and a plurality of elongated lead portions 12 for connecting the . The package regions 10a are regions corresponding to semiconductor devices 20 (described later). The package area 10a is an area surrounded by cutting areas 46 extending vertically and horizontally in FIGS. In the present embodiment, lead frame 10 includes a plurality of package regions 10a, but the present invention is not limited to this, and one lead frame 10 may have only one package region 10a.

A plurality of package regions 10 a are connected to each other via connecting bars (support members) 13 . The connecting bar 13 supports the die pad 11 and the lead portion 12 and extends along the X and Y directions. Here, the X direction and the Y direction are two directions parallel to each side of the die pad 11 in the plane of the lead frame 10, and the X direction and the Y direction are orthogonal to each other. Also, the Z direction is a direction perpendicular to both the X direction and the Y direction. The length L1 of one side of the package region 10a may be 3 mm or more and 10 mm or less.

The die pad 11 has a substantially square planar shape, and a semiconductor element 21, which will be described later, is mounted on the surface thereof. The planar shape of the die pad 11 is not limited to a square, and may be a polygon such as a rectangle. Suspension leads 14 are connected to the four corners of the die pad 11 , and the die pad 11 is connected and supported to the connecting bar 13 or the peripheral region 18 via the four suspension leads 14 . Each suspension lead 14 is formed thin from the back side by half-etching over the entire area. However, the present invention is not limited to this, and only a portion of the suspension lead 14 may be thinned from the back surface side, and the entire suspension lead 14 may not be thinned.

Each connecting bar 13 is arranged around the package area 10a and outside the package area 10a. Each connecting bar 13 has an elongated rod shape in plan view, and its width W2 (the distance in the direction perpendicular to the longitudinal direction of the connecting bar 13, the width of the maximum width portion 13e described later) is 95 μm or more. It may be 135 μm or less. A plurality of lead portions 12 are connected to each connecting bar 13 at intervals along the longitudinal direction of the connecting bar 13 .

Also, the two connecting bars 13 orthogonal to each other are connected to each other at a connecting portion 19 positioned around the package area 10a. The connecting portions 19 are arranged in the form of lattice points within the lead frame 10 . The connecting portion 19 has the same thickness as the metal substrate (metal substrate 31 to be described later) before processing without being thinned (half-etched).

The die pad 11 has a die pad thick portion 11a located in the center and a die pad thin portion 11b formed along the entire periphery of the die pad thick portion 11a. Of these, the die pad thick portion 11a is not half-etched and has the same thickness as the metal substrate (metal substrate 31 described later) before processing. Specifically, the thickness of the die pad thick portion 11a can be set to 80 μm or more and 200 μm or less, depending on the configuration of the semiconductor device 20 . On the other hand, the die pad thin portion 11b is formed thin from the back side by half etching. By providing the die pad thin portion 11b in this way, the die pad 11 can be made difficult to separate from the sealing resin 23 (described later).

Each lead portion 12 is connected to a semiconductor element 21 via a bonding wire 22 as will be described later, and is arranged with a space between it and the die pad 11 . Each lead portion 12 extends from the connecting bar 13 respectively. In this case, the plurality of lead portions 12 all have the same shape, but the present invention is not limited to this, and the plurality of lead portions 12 may have different shapes.

As described above, the plurality of lead portions 12 are arranged at intervals along the longitudinal direction of the connecting bar 13 around the die pad 11 . Adjacent lead portions 12 are shaped to be electrically insulated from each other after the semiconductor device 20 (described later) is manufactured. Moreover, the lead portion 12 is shaped to be electrically insulated from the die pad 11 after the semiconductor device 20 is manufactured. External terminals 17 electrically connected to an external mounting substrate (not shown) are formed on the rear surface of the lead portion 12 . Each external terminal 17 is exposed to the outside from the semiconductor device 20 after manufacturing the semiconductor device 20 (described later).

In this case, the external terminals 17 are arranged in one row along each side of the die pad 11 in plan view. However, the present invention is not limited to this, and the external terminals 17 may be arranged in a zigzag pattern in plan view so as to be alternately positioned inside and outside the adjacent lead portions 12 .

An internal terminal 15 is formed on the surface of each lead portion 12 . The internal terminals 15 are regions electrically connected to the semiconductor element 21 via bonding wires 22 as will be described later. For this reason, a plated portion for improving adhesion to the bonding wire 22 may be provided on the internal terminal 15 .

A base end portion of each lead portion 12 is connected to a connecting bar 13 . Each lead portion 12 extends perpendicularly to the longitudinal direction of the connecting bar 13 to which the lead portion 12 is connected. However, not limited to this, a part or all of each lead portion 12 may extend obliquely with respect to the connecting bar 13 .

By the way, the lead frame 10 according to the present embodiment is cut by two steps of sawing, as will be described later. That is, first, the lead frame 10 is partially cut (step cut) by about half the thickness along the connecting bar 13 by the first sawing. Thereafter, a second sawing is performed using a cutting blade 38 (described below) that is thinner than a step cutting blade 37 (described below) used for step cutting to separate the leadframes 10 from each other.

For this reason, the lead frame 10 is provided with a step-cut region 45 that is step-cut and a cutting region 46 that is separated by dicing along the length direction of the connecting bar 13 . In plan view, the entire connecting bar 13 is positioned inside the corresponding cut area 46 , and the entire cut area 46 is positioned inside the corresponding step cut area 45 . Further, the step cut region 45, the cut region 46 and the widthwise center line CL of the connecting bar 13 are aligned with each other.

The step-cut region 45 is a region that is step-cut (half-cut) by approximately half in the thickness direction (Z direction) from the back side of the lead frame 10 by the first sawing after resin sealing, and is parallel to each other in plan view. It is partitioned by a pair of outer edges S1, S1. The step cut regions 45 are arranged in a grid pattern along the outer periphery of the package region 10a and extend in the X direction or the Y direction. The step cut region 45 extends from the package region 10a to the outer peripheral region 18 and crosses the outer peripheral region 18 in the width direction. The width W3 of the step-cut region 45 corresponds to the width of a step-cutting blade 37 (described later) that performs step-cutting, and is wider than the width W2 of the connecting bar 13 . Specifically, the width W3 of the step cut region 45 may be 30 μm or more and 80 μm or less.

The cutting area 46 is an area in which the entire thickness direction (Z direction) of the lead frame 10 is cut by the second sawing, and is defined by a pair of outer edges C1, C1 parallel to each other in plan view. The cutting areas 46 are arranged in a grid pattern along the outer periphery of the package area 10a and extend in the X direction or the Y direction. The cutting area 46 extends from the package area 10a to the outer peripheral area 18 and traverses the outer peripheral area 18 in the width direction. The outer edge of the package area 10a coincides with the outer edges C1, C1 of the cutting area 46. As shown in FIG. The width W4 of the cutting area 46 corresponds to the width of the cutting blade 38 (described later) for the second sawing, and is wider than the width W2 of the connecting bar 13 and narrower than the width W3 of the step cut area 45 ( W2<W4<W3). Specifically, the width W4 of the cutting area 46 may be 10 μm or more and 40 μm or less.

Next, the configuration of the connecting bar 13 will be further described with reference to FIGS. 4 and 5. FIG.

As shown in FIG. 4, the connecting bar 13 has a lead connecting portion 13h to which the lead portion 12 is connected, and an intermediate portion 13j located between the adjacent lead connecting portions 13h, 13h. The lead connecting portions 13 h and intermediate portions 13 j are alternately arranged along the length direction of the connecting bar 13 . The lead connecting portion 13h and the intermediate portion 13j of the connecting bar 13 are not thinned and have the same thickness as the metal substrate (metal substrate 31 described later) before processing. Thereby, the strength of the connecting bar 13 is increased as compared with the case where the connecting bar 13 is thinned. As a result, the width of the connecting bar 13 can be narrowed, and the interval between the package regions 10a can be narrowed.

FIG. 5 shows a vertical cross section of the connecting bar 13 (cross section taken along line VV in FIG. 4) at the intermediate portion 13j. As shown in FIG. 5, the connecting bar 13 has a cross section that is symmetrical in the left and right direction (X direction). The connecting bar 13 has a front surface 13a, a back surface 13b, a pair of side surfaces 13c positioned between the front surface 13a and the back surface 13b, and a pair of lateral protrusions 13d projecting laterally from the side surfaces 13c. ing. The front surface 13a and the rear surface 13b of the connecting bar 13 are made of unprocessed material surfaces (the front surface and the rear surface of the metal substrate 31, which will be described later). Further, the front surface 13a and the rear surface 13b of the connecting bar 13 are positioned on the same plane as the front surface and the rear surface of the die pad 11, respectively.

Each side surface 13c has a first side surface 13f located closer to the front surface 13a than the side protrusions 13d and a second side surface 13g located closer to the back surface 13b than the side protrusions 13d. Of these, the first side surface 13f extends from the side protrusion 13d to the surface 13a, and the second side surface 13g extends from the side protrusion 13d to the back surface 13b. The first side surface 13f and the second side surface 13g are curved inward in the width direction of the connecting bar 13, respectively.

In this case, the width W5 of the front surface 13a of the connecting bar 13 is wider than the width W6 of the back surface 13b of the connecting bar 13 (W5>W6). Specifically, the width W5 of the front surface 13a is preferably 80 μm or more and 120 μm or less, and the width W6 of the back surface 13b is preferably 60 μm or more and 100 μm or less. Moreover, it is preferable that the width W5 of the front surface 13a is wider than the width W6 of the back surface 13b by 15 μm or more and 25 μm or less. As a result, when step-cutting (half-cutting) the connecting bar 13 from the back side, the amount of cutting can be reduced, the amount of burrs can be reduced, and wear of the step-cutting blade 37 (described later) can be suppressed. can.

Further, in the present embodiment, the portion where the pair of lateral protrusions 13d are formed corresponds to the maximum width portion 13e of the connecting bar 13, which is the portion with the maximum width. The maximum width portion 13e exists between the front surface 13a and the rear surface 13b in the thickness direction (Z direction), that is, at a position different from the front surface 13a and the rear surface 13b. Specifically, the width W2 of the maximum width portion 13e can be 95 μm or more and 135 μm or less (W2>W5). Moreover, it is preferable that the width W2 of the maximum width portion 13e is wider than the width W5 of the surface 13a by 10 μm or more and 15 μm or less. As a result, the geometrical moment of inertia of the connecting bar 13 can be increased, and the strength of the connecting bar 13 can be increased. Further, after the connecting bar 13 is step-cut (half-cut) from the back side, the maximum width portion 13e or its neighboring region is exposed on the back side, so that the area of the connecting bar 13 viewed from the back side can be increased. can. As a result, a large current for plating can be applied to the connecting bar 13 when solder plating is formed after step cutting.

In FIG. 5, the maximum width portion 13e is formed at a substantially intermediate position between the front surface 13a and the rear surface 13b in the thickness direction (Z direction). That is, the distance T1 of the maximum width portion 13e from the back surface 13b is 40% or more and 60% or less of the thickness T2 of the connecting bar 13. As shown in FIG. Specifically, the distance T1 of the maximum width portion 13e from the rear surface 13b is preferably 40 μm or more and 100 μm or less, and the thickness T2 of the connecting bar 13 is preferably 80 μm or more and 200 μm or less. As a result, after step-cutting (half-cutting) the connecting bar 13 from the back side, the maximum width portion 13e or its neighboring region can be exposed to the back side. It is possible to apply a large current for plating to the

The lead frame 10 described above is made of a metal such as copper, copper alloy, 42 alloy (Ni 42% Fe alloy) as a whole. Further, the thickness of the lead frame 10 can be 80 μm or more and 200 μm or less, depending on the structure of the semiconductor device 20 to be manufactured.

In the present embodiment, the lead portions 12 are arranged along all four sides of the die pad 11, but the present invention is not limited to this. It's okay to be there.

Structure of Semiconductor Device Next, a semiconductor device according to the present embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 and 7 are diagrams showing the semiconductor device (QFN type) according to this embodiment.

As shown in FIGS. 6 and 7, a semiconductor device (semiconductor package) 20 includes a die pad 11, a plurality of lead portions 12 arranged around the die pad 11, a semiconductor element 21 mounted on the die pad 11, A plurality of bonding wires (connecting members) 22 for electrically connecting the lead portions 12 and the semiconductor element 21 are provided. Also, the die pad 11 , the lead portion 12 , the semiconductor element 21 and the bonding wires 22 are sealed with a sealing resin 23 .

The die pad 11 and the lead portion 12 are produced from the lead frame 10 described above. A portion of the lead portion 12 located on the periphery of the sealing resin 23 is thinned from the rear side by step cutting to form a stepped step cut portion 45a. The step cut portion 45a is not filled with the sealing resin 23. As shown in FIG. The step cut portion 45a may be covered with solder plating. Also, burrs may be generated on the side surface 45b of the step cut portion 45a during the step cutting, and the burrs may protrude toward the back side. The depth D1 of the step cut portion 45a may be the same as the depth D2 of the half-etched portion (die pad thin portion 11b, etc.) or may be deeper than the depth D2.

In addition, the configurations of the die pad 11 and the lead portion 12 are the same as those shown in FIGS. 1 to 5 described above except for the regions not included in the semiconductor device 20, so detailed description thereof will be omitted here.

As the semiconductor element 21, it is possible to use various semiconductor elements that have been generally used in the past, and it is not particularly limited. This semiconductor element 21 has a plurality of electrodes 21a to which bonding wires 22 are attached respectively. The semiconductor element 21 is fixed to the surface of the die pad 11 with an adhesive 24 such as die bonding paste.

Each bonding wire 22 is made of a highly conductive material such as gold or copper. Each bonding wire 22 has one end connected to the electrode 21 a of the semiconductor element 21 and the other end connected to the internal terminal 15 of each lead portion 12 . In addition, the internal terminal 15 may be provided with a plating portion for improving adhesion to the bonding wire 22 .

As the sealing resin 23, a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin can be used. The thickness of the entire sealing resin 23 can be about 300 μm or more and 1200 μm or less. Also, one side of the sealing resin 23 (one side of the semiconductor device 20) can be, for example, 6 mm or more and 16 mm or less. In FIG. 6, the portion of the sealing resin 23 located closer to the surface than the die pad 11 and the lead portion 12 is omitted.

Method for Manufacturing Lead Frame Next, a method for manufacturing the lead frame 10 shown in FIGS. 1 to 5 will be described with reference to FIGS. 8(a) to 8(e). 8A to 8E are cross-sectional views (views corresponding to FIG. 3) showing the manufacturing method of the lead frame 10. First, as shown in FIG.

First, as shown in FIG. 8A, a flat metal substrate 31 is prepared. As the metal substrate 31, a substrate made of a metal such as copper, a copper alloy, or a 42 alloy (Ni 42% Fe alloy) can be used. It is preferable to use the metal substrate 31 which has been subjected to degreasing or the like on both sides thereof and to which cleaning treatment has been performed.

Photosensitive resists 32a and 33a are then applied to the entire front and back surfaces of the metal substrate 31 and dried (FIG. 8(b)). Conventionally known ones can be used as the photosensitive resists 32a and 33a.

Subsequently, the metal substrate 31 is exposed through a photomask and developed to form etching resist layers 32 and 33 having desired openings 32b and 33b (FIG. 8(c)).

Next, using the etching resist layers 32 and 33 as anti-corrosion films, the metal substrate 31 is etched with a corrosive liquid (FIG. 8(d)). Thereby, the outer shapes of the die pad 11, the lead portion 12 and the connecting bar 13 are formed. At this time, the connecting bar 13 is etched from its front surface side and back surface side, so that the width W5 of the front surface 13a becomes wider than the width W6 of the back surface 13b, and the maximum width of the connecting bar 13 (width W2). A maximum width portion 13e is formed between the front surface 13a and the rear surface 13b (see FIG. 5). Such a cross-sectional shape of the connecting bar 13 can be produced by appropriately setting the patterns of the etching resist layers 32 and 33 . The etchant can be appropriately selected according to the material of the metal substrate 31 to be used. Spray etching can be performed from

After that, the etching resist layers 32 and 33 are peeled off to obtain the lead frame 10 shown in FIGS. (FIG. 8(e)).

Method for Manufacturing Semiconductor Device Next, a method for manufacturing the semiconductor device 20 shown in FIGS. 6 and 7 will be described with reference to FIGS.

First, the lead frame 10 is manufactured by the method shown in FIGS. 8(a) to 8(e) (FIG. 9(a)).

Next, the semiconductor element 21 is mounted on the die pad 11 of the lead frame 10 . In this case, the semiconductor element 21 is placed and fixed on the die pad 11 using an adhesive 24 such as die bonding paste (die attach step) (FIG. 9B).

Next, the electrodes 21a of the semiconductor element 21 and the internal terminals 15 of the lead portions 12 are electrically connected to each other by bonding wires (connecting members) 22 (wire bonding step) (FIG. 9(c)). .

Next, a sealing resin 23 is formed by injection molding or transfer molding a thermosetting resin or thermoplastic resin to the lead frame 10 (resin sealing step) (FIG. 9D). In this manner, the lead frame 10 (the die pad 11, the lead portion 12 and the connecting bar 13), the semiconductor element 21 and the bonding wires 22 are sealed.

Subsequently, a part of the lead frame 10 in the thickness direction is cut along the step cut region 45 (step cut process: first sawing) (FIG. 10(a)).

During this time, a step-cutting blade 37 made of, for example, a diamond whetstone is prepared and moved along the step-cutting region 45 . At this time, the step cut region 45 is excised while rotating the step cut blade 37 . As a result, the connecting bar 13, the outer peripheral region 18 and the sealing resin 23 in the step cut region 45 are partially removed. By this step cutting, the connecting bar 13 and the outer peripheral region 18 of the step cut region 45 are cut halfway in the thickness direction to form a step cut portion 45a. This step cutting operation is repeated a plurality of times along the X direction and the Y direction, and the step cut portions 45a are formed in a grid pattern in plan view.

After this step cut process, a solder plated layer (not shown) is formed on the step cut portion 45a by electroplating.

By the way, FIG. 11 shows a cross section of the connecting bar 13 after the step cutting process. In this embodiment, the widest portion 13e of connecting bar 13 is positioned between front surface 13a and rear surface 13b. Therefore, after the step cutting process, the maximum width portion 13e or a portion in the vicinity thereof is exposed on the back side, and a wide cross-sectional area of the connecting bar 13 can be ensured. As a result, when forming the solder plating layer described above, a large current can be applied as the current for electroplating.

After that, the lead frame 10 and the sealing resin 23 are cut for each package region 10a (cutting process: second sawing) (FIG. 10B).

At this time, a cutting blade 38 made of, for example, a diamond whetstone is prepared. The cutting blade 38 is narrower than the step cutting blade 37 described above. Next, the cutting area 46 is cut by rotating and moving the cutting blade 38 . As a result, the connecting bar 13, the outer peripheral region 18, and the sealing resin 23 in the cutting region 46 are cut (diced) over the entire thickness direction (Z direction). This cutting operation is repeated a plurality of times along the X and Y directions to form cutting lines in a grid pattern in plan view.

In this way, the lead frame 10 is separated for each semiconductor device 20, and the semiconductor devices 20 shown in FIGS. 6 and 7 are obtained (FIG. 9(c)).

As described above, according to the present embodiment, the width W5 of the front surface 13a of the connecting bar 13 is wider than the width W6 of the back surface 13b of the connecting bar 13. As shown in FIG. As a result, when the connecting bar 13 is cut from the back surface 13b side in the step cutting process, the generation of burrs can be reduced and the wear of the step cutting blade 37 can be suppressed.

Further, according to this embodiment, the maximum width portion 13e of the connecting bar 13 is located between the front surface 13a and the rear surface 13b. As a result, the geometrical moment of inertia of the connecting bar 13 can be increased, and the strength of the connecting bar 13 can be increased. As a result, it is possible to suppress the distortion caused in the connecting bar 13 by the pressure of the molten resin during resin sealing, and to perform the sawing in the step cutting process accurately. Further, after the step cutting process, a large cross-sectional area of the connecting bar 13 can be ensured, so that a large current can be applied as the current for electroplating for forming the solder plating layer. Furthermore, since the side protrusions 13d of the widest portion 13e serve as anchors, the connecting bar 13 is in close contact with the sealing resin 23, preventing the connecting bar 13 from peeling off from the sealing resin 23 during sawing. can be done.

Further, according to the present embodiment, the two connecting bars 13 orthogonal to each other are connected to each other by the connecting portion 19 , and the die pad 11 and the connecting portion 19 are connected to each other by the suspension leads 14 . Further, the connecting portion 19 is not thinned (half-etched), and the suspension lead 14 is thinned (half-etched) from the back side. As a result, the periphery of the package region 10a can be firmly fixed, and distortion of the connecting bar 13 and the die pad 11 during resin sealing can be suppressed. Furthermore, since the back surface of the suspension lead 14 is thinned, the suspension lead 14 is in close contact with the sealing resin 23 , and separation of the die pad 11 and the suspension lead 14 from the sealing resin 23 can be suppressed.

Modifications Next, each modification of the lead frame according to the present embodiment will be described with reference to FIGS. 12 to 17. FIG. The modifications shown in FIGS. 12 to 17 are different in the configuration of the connecting bar or lead portions, and other configurations are substantially the same as the embodiment shown in FIGS. 1 to 11. FIG. 12 to 17, the same parts as those in FIGS. 1 to 11 are denoted by the same reference numerals, and detailed description thereof is omitted.

(Modification 1)
In the modification (Modification 1) shown in FIG. 12, the maximum width portion 13e of the connecting bar 13 is located closer to the front surface 13a than the intermediate position between the front surface 13a and the rear surface 13b of the connecting bar 13. As shown in FIG. In this case, the distance T3 of the maximum width portion 13e from the rear surface 13b is more than 50% and 75% or less of the thickness T2 of the connecting bar 13. As shown in FIG. Specifically, the distance T3 of the maximum width portion 13e from the rear surface 13b is preferably more than 40 μm and 150 μm or less.

The width W7 of the front surface 13a of the connecting bar 13 is preferably 100 μm or more and 300 μm or less, and the width W8 of the back surface 13b is preferably 50 μm or more and 150 μm or less. Furthermore, it is preferable that the width W9 of the maximum width portion 13e is not less than 150 μm and not more than 350 μm.

In this way, the maximum width portion 13e of the connecting bar 13 is positioned closer to the front surface 13a than the middle position between the front surface 13a and the rear surface 13b, so that the connecting bar 13 is positioned closer to the rear surface 13b than the middle position. It is possible to reduce the cross-sectional area of the part where As a result, when the connecting bar 13 is cut from the back surface 13b side in the step cutting process, the generation of burrs can be reduced and the wear of the step cutting blade 37 can be suppressed.

(Modification 2)
The modification shown in FIG. 13 (modification 2) has a concave portion 65 formed in the surface 13a of the connecting bar 13, and the rest of the construction is substantially the same as the construction of the connecting bar 13 shown in FIG. This recessed portion 65 extends along the longitudinal direction of the connecting bar 13 in a groove shape over the entire area or a partial area thereof. The concave portion 65 is formed in a concave shape from the surface 13a side of the connecting bar 13 by half-etching, and has a substantially semicircular or substantially C-shaped cross section. On each side of the recess 65 are formed non-etched side regions 66 respectively.

The width W10 of the concave portion 65 is preferably 60 μm or more and 150 μm or less, and the depth D3 of the concave portion 65 is preferably 30 μm or more and 100 μm or less.

By forming the concave portion 65 on the surface 13a of the connecting bar 13 in this manner, the cross-sectional area of the portion of the connecting bar 13 located closer to the surface 13a than the intermediate position can be reduced. As a result, when cutting the connecting bar 13 in the cutting process, it is possible to reduce the occurrence of burrs and suppress wear of the cutting blade 38 .

(Modification 3)
The modification shown in FIG. 14 (modification 3) has a concave portion 67 formed in the back surface 13b of the connecting bar 13, and the rest of the configuration is substantially the same as the configuration of the connecting bar 13 shown in FIG. The recess 67 extends along the longitudinal direction of the connecting bar 13 in the form of a groove over the entire area or a partial area thereof. The concave portion 67 is formed in a concave shape from the back surface 13b side of the connecting bar 13 by half-etching, and has a substantially semicircular or substantially C-shaped cross section. On each side of the recess 67 are formed non-etched side regions 68 .

The width W11 of the recess 67 is preferably 60 μm or more and 100 μm or less, and the depth D4 of the recess 67 is preferably 30 μm or more and 80 μm or less.

By forming the recess 67 in the back surface 13b of the connecting bar 13 in this manner, the cross-sectional area of the connecting bar 13 on the back surface 13b side can be reduced. As a result, when the connecting bar 13 is cut from the back surface 13b side in the step cutting process, it is possible to reduce the occurrence of burrs and suppress the wear of the step cutting blade 37 .

(Modification 4)
The modification shown in FIG. 15 (modification 4) has a recess 65 formed on the front surface 13a of the connecting bar 13 in addition to the recess 67 on the back surface 13b side of the connecting bar 13. The configuration is substantially the same as that of the connecting bar 13 shown in 14 . The recessed portion 65 on the surface 13a side extends along the longitudinal direction of the connecting bar 13 in the shape of a groove over the entire area or a partial area thereof. The concave portion 65 on the surface 13a side is formed in a concave shape from the surface 13a side of the connecting bar 13 by half-etching, and has a substantially semicircular or substantially C-shaped cross section. On each side of the recess 65 are formed non-etched side regions 66 respectively.

The width W12 of the concave portion 65 on the surface 13a side is preferably 60 μm or more and 150 μm or less, and the depth D5 of the concave portion 65 is preferably 30 μm or more and 100 μm or less.

By thus forming the concave portions 65 and 67 on the front surface 13a and the rear surface 13b of the connecting bar 13, respectively, the cross section of the connecting bar 13 can be reduced. As a result, when the connecting bar 13 is cut from the back surface 13b side in the step cutting process, it is possible to reduce the occurrence of burrs and suppress the wear of the step cutting blade 37 . Also, when cutting the connecting bar 13 in the cutting process, it is possible to reduce the occurrence of burrs and suppress the wear of the cutting blade 38 .

(Modification 5)
16, the portion of the lead portion 12 that is connected to the connecting bar 13 is tapered in plan view, and the other configuration is shown in FIG. It is substantially the same as the shown configuration. In this case, the lead portion 12 is composed of a rectangular portion 12b located inside (die pad 11 side) and a trapezoidal portion 12c located outside (connecting bar 13 side). Among them, the trapezoidal portion 12c is formed in a tapered shape in plan view, and the width thereof gradually narrows from the inside toward the outside. Moreover, it is preferable that the trapezoidal portion 12 c extends from the connecting bar 13 to the inner side of the step cut region 45 .

As described above, the portion of the lead portion 12 that is connected to the connecting bar 13 is formed in a tapered shape in a plan view. The area of the step cut portion 45a does not increase significantly. Moreover, the amount of burrs generated during the step cutting process and the cutting process can be reduced, and wear of the step cutting blade 37 and the cutting blade 38 can be suppressed.

(Modification 6)
The modification shown in FIG. 17 (modification 6) has notches 13k formed in portions of the connecting bar 13 located on both sides of the lead portion 12. The other configuration is shown in FIG. It is substantially the same as the shown configuration. In this case, the connecting bar 13 is narrowed at the notch 13k. The lead portion 12 has a first rectangular portion 12d positioned inside (die pad 11 side) and a second rectangular portion 12d positioned outside (connecting bar 13 side) and narrower than the first rectangular portion 12d. 12e.

Thus, by forming the notch portions 13k in the portions of the connecting bar 13 located on both sides of the lead portion 12, respectively, the amount of burrs generated during the step cutting process and the cutting process can be reduced, and the step cutting blade can be Wear of 37 and cutting blade 38 can be suppressed.

It is also possible to appropriately combine a plurality of constituent elements disclosed in the above embodiments and modifications as necessary. Alternatively, some components may be deleted from all the components shown in each of the above embodiments and modifications.

REFERENCE SIGNS LIST 10 lead frame 10a package region 11 die pad 12 lead portion 13 connecting bar 13a front surface 13b rear surface 13e maximum width portion 14 suspension lead 15 internal terminal 17 external terminal 18 outer peripheral region 19 connecting portion 20 semiconductor device 21 semiconductor element 22 bonding wire 23 sealing resin 45 step cut area 46 cutting area

Claims (7)

in the lead frame,
a die pad;
a lead portion provided around the die pad;
A connecting bar to which the lead portion is connected,
The width of the front surface of the connecting bar is wider than the width of the back surface of the connecting bar,
A maximum width portion of the connecting bar, which is the maximum width, is located between the front surface and the back surface of the connecting bar,
The two connecting bars orthogonal to each other are connected to each other by a connecting portion positioned outside the region corresponding to the semiconductor device, the die pad and the connecting portion are connected to each other by suspension leads, and the connecting portion is thinned. and the suspension lead is thinned from the back side ,
The connecting bar is not thinned,
a maximum width portion of the connecting bar having the maximum width W2 is located between the front surface and the back surface of the connecting bar and is located at a position different from the front surface and the back surface;
When the width of the front surface of the connecting bar is W5 and the width of the back surface of the connecting bar is W6,
A lead frame that satisfies the relationship W2>W5>W6 . 2. The lead frame according to claim 1 , wherein said maximum width portion is located closer to said front surface than an intermediate position between said front surface and said rear surface of said connecting bar. 3. The lead frame according to claim 1, wherein at least one of said front surface and said back surface of said connecting bar is formed with a recess. 4. The lead frame according to claim 1 , wherein a portion of said lead portion connected to said connecting bar is tapered in plan view. 5. The lead frame according to claim 1 , wherein notches are formed in portions of said connecting bar located on both sides of said lead. The width of the surface of the connecting bar is wider than the width of the back surface of the connecting bar by 15 μm or more and 25 μm or less, and the width of the maximum width portion is wider than the width of the surface of the connecting bar by 10 μm or more and 15 μm or less. Item 6. The lead frame according to any one of Items 1 to 5 . In a method for manufacturing a semiconductor device,
A step of providing a lead frame according to any one of claims 1 to 6 ;
mounting a semiconductor element on the die pad of the lead frame;
a step of electrically connecting the semiconductor element and the lead portion with a connecting member;
a step of sealing the die pad, the lead portion, the semiconductor element, and the connection member with a sealing resin;
cutting a portion of the lead frame in the thickness direction from the back side along the connecting bar;
and cutting the lead frame and the sealing resin for each semiconductor device.

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