Lead frame and manufacturing method thereof, and semiconductor device

Abstract

To provide a lead frame having a structure in which a short circuit is unlikely to occur between adjacent leads.SOLUTION: A lead frame includes a frame portion and a plurality of leads that protrude from the inner edge of the frame portion to the inside of the frame portion, and the leads have a lower surface, an upper surface opposite the lower surface, and a step surface that is recessed from the upper surface toward the lower surface, and in a vertical cross section cut through the step surface and perpendicular to the direction in which the leads protrude, the step surface is convex toward the upper surface.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a lead frame, a manufacturing method thereof, and a semiconductor device. [Background technology]

[0002] A semiconductor device having a semiconductor chip mounted on a lead frame is known. When manufacturing such a semiconductor device, a plurality of semiconductor chips are mounted on the lead frame to form a plurality of regions that will become semiconductor devices, and then the lead frame is cut at predetermined positions to obtain a plurality of individual semiconductor devices.

[0003] When cutting, multiple adjacent leads on a lead frame may be cut. This cutting process can cause burrs on the leads. If burrs are generated on the leads, there is a risk that adjacent leads that are normally electrically non-conductive may be short-circuited by the burrs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-77279 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above points, and has as its object to provide a lead frame having a structure in which short circuits are less likely to occur between adjacent leads. [Means for solving the problem]

[0006] This lead frame has a frame portion and a plurality of leads that protrude from the inner edge of the frame portion to the inside of the frame portion, and the leads have a lower surface, an upper surface opposite the lower surface, and a step surface that is recessed from the upper surface toward the lower surface, and in a vertical cross section cut through the step surface and perpendicular to the direction in which the leads protrude, the step surface is convex toward the upper surface. [Effects of the Invention]

[0007] According to the disclosed technology, it is possible to provide a lead frame having a structure in which short circuits are unlikely to occur between adjacent leads. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a top view illustrating an example of the entire lead frame according to the first embodiment. FIG. [Figure 2] 3 is a top view illustrating the vicinity of an individual region of the lead frame according to the first embodiment. FIG. [Figure 3] 3 is a bottom view illustrating the vicinity of an individual region of the lead frame according to the first embodiment. FIG. [Figure 4] 3 is a cross-sectional view illustrating the vicinity of an individual region of the lead frame according to the first embodiment. FIG. [Figure 5] 1A to 1C are views (part 1) illustrating a manufacturing process of the lead frame according to the first embodiment. [Figure 6] 5A to 5C are diagrams illustrating the manufacturing process of the lead frame according to the first embodiment (part 2). [Figure 7] 10A to 10C are views (part 3) illustrating the manufacturing process of the lead frame according to the first embodiment. [Figure 8] 10A and 10B are diagrams illustrating a semiconductor device according to a second embodiment. [Figure 9] 10A to 10C are diagrams illustrating a manufacturing process of a semiconductor device according to a second embodiment. [Figure 10] 10A and 10B are diagrams illustrating a lead frame and a semiconductor device according to a first modification. [Figure 11] 10 is a top view illustrating the vicinity of an individual region of a lead frame according to Modification 2. FIG. [Figure 12] 10 is a cross-sectional view illustrating the vicinity of an individual region of a lead frame according to Modification 2. FIG. [Figure 13] FIG. 11(b) is a top view illustrating a method for fabricating the shape shown in FIG. [Figure 14] 11(b) is a bottom view illustrating a method for producing the shape shown in FIG. [Figure 15] FIG. 10 is a top view illustrating a side edge. [Figure 16] 11 is a top view illustrating the vicinity of an individual region of a lead frame according to Modification 3. FIG. [Figure 17] 11 is a cross-sectional view illustrating the vicinity of an individual region of a lead frame according to a third modification. FIG. [Figure 18] FIG. 16(b) is a top view illustrating a method for fabricating the shape shown in FIG. [Figure 19] FIG. 16(b) is a bottom view illustrating a method for producing the shape shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] First Embodiment [Lead frame] FIG. 1 is a top view illustrating an example of the entire lead frame according to the first embodiment. In FIG. 1, the X-axis, Y-axis, and Z-axis are perpendicular to one another. Referring to FIG. 1, the lead frame 10 is, for example, rectangular in top view. In the example of FIG. 1, the lead frame 10 has a long side extending in the X-axis direction and a short side extending in the Y-axis direction. Note that the lead frame 10 may also be square or have other shapes in top view.

[0011] In the example of FIG. 1 , three regions 101, 102, and 103 are defined in the lead frame 10 when viewed from above, and a plurality of individual regions R are defined in each of the regions 101, 102, and 103. The individual regions R are, for example, arranged one-dimensionally or two-dimensionally and spaced apart from one another. The individual regions R are eventually cut into individual pieces to become parts of the semiconductor device. The lead frame 10 may have one, two, four, or more regions. The number of individual regions R in each region can be determined arbitrarily.

[0012] 1, the individual regions R are shown in a simplified rectangular shape, but the individual regions R do not need to be rectangular and may have a more complex shape that matches the shape of the semiconductor device. Examples of materials that can be used for the lead frame 10 include copper (Cu), copper alloys, and 42 alloys. The thickness of the lead frame 10 can be, for example, 10 μm or more and 200 μm or less.

[0013] 2A and 2B are top views illustrating the vicinity of individual regions of the lead frame according to the first embodiment, with FIG. 2A showing the entire individual region and FIG. 2B showing an enlarged view of portion P of FIG. 2A. FIG. 3 is a bottom view illustrating the vicinity of individual regions of the lead frame according to the first embodiment. FIG. 4A is a cross-sectional view illustrating the vicinity of individual regions of the lead frame according to the first embodiment, with FIG. 4A showing a cross-section along line AA in FIG. 2A, FIG. 4B showing a cross-section along line BB in FIG. 2B, and FIG. 4C showing a cross-section along line CC in FIG. 2B.

[0014] As shown in FIGS. 2 to 4, the lead frame 10 has a frame portion 11, a plurality of leads 12, a die pad 13, and a support bar 14. For example, a plurality of elongated portions extending in the X-axis direction and a plurality of elongated portions extending in the Y-axis direction are arranged in a lattice pattern to form the frame portion 11. The frame portion 11 is arranged so as to surround each individual region R in a top view. The frame portion 11 may have a portion common to one individual region R and an individual region R adjacent to that individual region R. The width of the frame portion 11 may be, for example, approximately 0.1 to 0.2 mm.

[0015] The leads 12 protrude inward from the inner edge of the frame 11. The leads 12 protrude, for example, perpendicularly from the inner edge of the frame 11. The width of the leads 12 can be, for example, approximately 0.15 to 0.25 mm. A plurality of leads 12 are arranged spaced apart from one another. The lead 12 has a lower surface 12a, an upper surface 12b opposite the lower surface 12a, and a stepped surface 12c recessed from the upper surface 12b toward the lower surface 12a. The lower surface 12a and the upper surface 12b are, for example, parallel. In the extension direction of the frame 11, the width of the stepped surface 12c is equal to the width of the upper surface 12b. The stepped surface 12c can be provided on the lead 12 adjacent to the inner edge of the frame 11. Furthermore, the step surface 12c can be provided between the frame 11 and the portion of the lead 12 that is connected to the semiconductor chip (the portion that is connected to the metal wire 130 or the bonding member 125, which will be described later).

[0016] In a longitudinal cross section taken through the stepped surface 12c and perpendicular to the direction in which the leads 12 protrude, i.e., in the cross section shown in Fig. 4(c), the stepped surface 12c is convex toward the upper surface 12b. In the cross section shown in Fig. 4(c), the stepped surface 12c has an R-shape in which the height is highest at the center in the X-axis direction and gradually decreases from the center to the periphery in the X-axis direction.

[0017] In a longitudinal cross section taken through the step surface 12c and parallel to the direction in which the lead 12 protrudes, i.e., in the cross section shown in FIG. 4(a), the step surface 12c is, for example, parallel to the lower surface 12a. In the Z-axis direction, the distance from the lower surface 12a to the highest point of the step surface 12c is approximately half the distance from the lower surface 12a to the upper surface 12b. In the cross section shown in FIG. 4(c), the side surface connecting the lower surface 12a and the step surface 12c may be flat or curved. Furthermore, if the side surface connecting the lower surface 12a and the step surface 12c is flat, this plane may be perpendicular to or inclined relative to the lower surface 12a.

[0018] 4(b), the side surface 12d connecting the lower surface 12a and the upper surface 12b protrudes laterally beyond the lower surface 12a and the upper surface 12b at the center in the thickness direction (Z-axis direction). The upper surface 11b of the frame 11 is flush with the upper surface 12b of the lead 12, and the lower surface 11a of the frame 11 is flush with the lower surface 12a of the lead 12. The width of the step surface 12c is narrower than the width of the portion of the side surface 12d protruding laterally at the center in the thickness direction (Z-axis direction) of the lead 12.

[0019] The die pad 13 is disposed in the center of the individual region R and spaced apart from the leads 12. The die pad 13 has, for example, a rectangular shape when viewed from above. The die pad 13 has a second step surface 13c on the outer periphery of the lower surface 13a, which is recessed from the lower surface 13a toward the upper surface 13b. In other words, the outer periphery of the die pad 13 is thinner than the center.

[0020] The support bars 14 connect the four corners of the die pad 13 to the four corners of the frame portion 11. That is, the die pad 13 is connected to and supported by the frame portion 11 by the support bars 14. The support bars 14 are thinned in the same manner as the outer periphery of the die pad 13. The upper surface 14b of the support bar 14 is flush with the upper surface 13b of the die pad 13, and the lower surface 14a of the support bar 14 is flush with the second step surface 13c of the die pad 13. The upper surface 14b of the support bar 14 is flush with the upper surface 11b of the frame portion 11. The lower surface 14a of the support bar 14 is located higher than the lower surface 11a of the frame portion 11.

[0021] [Lead frame manufacturing method] Next, a method for manufacturing a lead frame according to the first embodiment will be described. FIG. 5 is a diagram (part 1) illustrating the manufacturing process of the lead frame according to the first embodiment, showing a cross section corresponding to FIG. 4(a). FIG. 6 is a diagram (part 2) illustrating the manufacturing process of the lead frame according to the first embodiment, showing a cross section corresponding to FIG. 4(b). FIG. 7 is a diagram (part 3) illustrating the manufacturing process of the lead frame according to the first embodiment, showing a cross section corresponding to FIG. 4(c). FIGS. 5(a), 6(a), and 7(a) form one process. Similarly, FIGS. 5(b), 6(b), and 7(b) form one process. Similarly, FIGS. 5(c), 6(c), and 7(c) form one process.

[0022] First, as shown in Figures 5(a), 6(a), and 7(a), a metal plate material 10S having a predetermined shape is prepared, and a resist layer 310 having openings 310x is provided on the upper surface of the plate material 10S, and a resist layer 320 having openings 320x is provided on the lower surface. As shown in Figure 1, for example, three regions 101, 102, and 103 are defined in the plate material 10S when viewed from above, and multiple individual regions R are defined in each of the regions 101, 102, and 103. Here, the vicinity of one individual region R is illustrated.

[0023] The openings 310x and 320x are arranged according to the shape of the lead frame 10 to be formed. For example, at the position shown in FIG. 5(a), the openings 310x and 320x include overlapping portions in a top view and non-overlapping portions in a top view. At the position shown in FIG. 6(a), the openings 310x and 320x overlap in a top view. At the position of region Q shown in FIG. 7(a), the resist layer 310 is not arranged, and only the resist layer 320 having the openings 320x is arranged. That is, region Q is an area where the resist layer 310 is not provided, and only the resist layer 320 is provided, in a top view. Although not shown, in the portion where the support bar 14 is to be formed, the upper surface side of the plate material 10S is covered with the resist layer 310, and the openings 320x are arranged on the lower surface side.

[0024] 5(b), 6(b), and 7(b), the plate material 10S is etched (e.g., wet etching) via the resist layers 310 and 320 to form a lead frame 10. As shown in FIGS. 2 to 4, the lead frame 10 has a frame portion 11, a plurality of leads 12 that protrude from the inner edge of the frame portion 11 toward the inside of the frame portion 11 and have a lower surface 12a, an upper surface 12b opposite the lower surface 12a, and a stepped surface 12c recessed from the upper surface 12b toward the lower surface 12a, a die pad 13, and a support bar 14.

[0025] The etching penetrates the plate material 10S in the areas where the openings 310x and 320x overlap in a top view. Because the etching proceeds isotropically, a side surface 12d is formed in the central portion in the thickness direction (Z-axis direction), protruding laterally beyond the bottom surface 12a and the top surface 12b, as shown in FIG. 6(b), for example. Furthermore, in the area Q where the resist layer 310 is not provided and only the resist layer 320 is provided in a top view, only the top surface of the plate material 10S is half-etched, forming a step surface 12c that is convex toward the top surface 12b, as shown in FIG. 7(b). Furthermore, in the areas where the openings 310x are not provided but the openings 320x are provided in a top view, only the bottom surface of the plate material 10S is half-etched. For example, as shown in FIG. 5(b), a second step surface 13c is formed.

[0026] The upper and lower surfaces of the frame 11 are covered with a resist layer and are therefore not half-etched. As a result, the frame 11 remains the same thickness as the plate material 10S and is not thinned, which increases the rigidity of the lead frame 10 and prevents deformation of the lead frame 10.

[0027] 5(c), 6(c), and 7(c), the resist layers 310 and 320 are removed to complete the lead frame 10. After the resist layers 310 and 320 are removed, a plating layer such as silver plating may be formed on the wire bonding portion of the lead 12.

[0028] (Second embodiment) The second embodiment relates to a semiconductor device manufactured using the lead frame 10 according to the first embodiment.

[0029] [Semiconductor Devices] 8A and 8B are diagrams illustrating a semiconductor device according to the second embodiment, in which FIG. 8A is a cross-sectional view and FIG. 8B is a side view.

[0030] 8, the semiconductor device 100 includes a lead frame 101, a semiconductor chip 110, an adhesive 120, metal wires 130 (bonding wires), and a resin part 140. The semiconductor device 100 is a QFN (Quad Flat Non-leaded package) type package.

[0031] The lead frame 101 is obtained by dividing the lead frame 10 into individual pieces, and is the inner portion of the individual region R of the lead frame 10. The lead frame 101 includes leads 12, a die pad 13, and a support bar 14. The lead frame 101 does not include a frame portion.

[0032] The semiconductor chip 110 is mounted face-up on the upper surface 13b of the die pad 13. The semiconductor chip 110 can be mounted (die-bonded) on the upper surface 13b of the die pad 13 using an adhesive 120 such as Ag paste. The electrode terminals 115 of the semiconductor chip 110 are electrically connected (wire-bonded) to the upper surfaces 12b of the leads 12 via metal wires 130 such as gold wires or copper wires.

[0033] The resin portion 140 is provided on the lead frame 101. For example, a so-called mold resin obtained by adding a filler to an epoxy resin can be used as the resin portion 140. The resin portion 140 covers at least the semiconductor chip 110, the metal wires 130, the upper surfaces 12b of the leads 12, the side surfaces 12d of the leads 12, the stepped surfaces 12c of the leads 12, the upper surface 13b of the die pad 13, and the second stepped surface 13c of the die pad 13. As shown in FIG. 4(b), the side surfaces 12d of the leads 12 have a shape in which the central portions in the thickness direction protrude laterally beyond the lower surface 12a and the upper surface 12b, thereby increasing the contact area with the resin portion 140. This improves the adhesion between the leads 12 and the resin portion 140.

[0034] The resin part 140 exposes the lower surface 12a of the lead 12, the outer surface 12e of the lead 12, and the lower surface 13a of the die pad 13. The outer surface 12e of the lead 12 is a cut surface of the lead 12 cut from the frame part 11. When viewed from a direction perpendicular to the side surface of the resin part 140, the step surface 12c is convex toward the upper surface. When viewed from a direction perpendicular to the side surface of the resin part 140, the step surface 12c is the upper edge of the outer surface 12e.

[0035] The lower surface 12a and / or the outer surface 12e of the lead 12 can be used as, for example, an external connection terminal. The die pad 13 may be connected to a ground terminal of the semiconductor chip 110 by a metal wire, thereby allowing the die pad 13 to be used as a ground conductor.

[0036] [Method of manufacturing a semiconductor device] 9A to 9C are views illustrating the manufacturing process of the semiconductor device according to the second embodiment.

[0037] 9(a), the semiconductor chip 110 is mounted face-up on the upper surface 13b of the die pad 13 in each individual region R of the lead frame 10 via an adhesive 120, and the adhesive 120 is cured by heating. This fixes the semiconductor chip 110 to the upper surface 13b of the die pad 13. Next, the electrode terminals 115 formed on the upper surface of the semiconductor chip 110 are electrically connected to the upper surfaces 12b of the leads 12 via metal wires 130 by wire bonding.

[0038] 9(b), a resin portion 140 is formed to seal the semiconductor chip 110 and the like. For example, a so-called mold resin in which a filler is contained in an epoxy resin can be used as the resin portion 140. The resin portion 140 can be formed by, for example, a transfer molding method or a compression molding method.

[0039] Next, as shown in FIG. 9(c), the structure shown in FIG. 9(b) is cut at the step surface 12c indicated by the dashed line, thereby completing a plurality of individual semiconductor devices 100. Cutting can be performed, for example, using a rotating blade 400. The step surface 12c is thinned by half-etching, allowing for easy cutting with the blade 400. Furthermore, in a cross section taken perpendicular to the direction in which the leads 12 protrude through the step surface 12c, the step surface 12c is convex toward the upper surface 12b. This reduces the contact area between the blade 400 and the step surface 12c, thereby reducing the risk of burrs occurring at the cut portion. As a result, the risk of short-circuiting adjacent leads 12 due to burrs can be reduced. Furthermore, the reduced contact area between the blade 400 and the step surface 12c reduces stress on the leads 12 during cutting, reducing the likelihood of peeling between the leads 12 and the resin portion 140. These factors contribute to improved reliability of the semiconductor device 100.

[0040] (Variation 1) In the first modification, an example of a lead frame that does not have a die pad or a support bar and a semiconductor device that uses the lead frame will be shown.

[0041] 10A and 10B are diagrams illustrating a lead frame and a semiconductor device according to Modification 1. Fig. 10A is a cross-sectional view of the lead frame, Fig. 10B is a cross-sectional view of the semiconductor device, and Fig. 10C is a side view of the semiconductor device.

[0042] 10(a) differs from the lead frame 10 in that it does not have a die pad or a support bar. The shapes of the frame portion 11 and the leads 12 are the same as those of the lead frame 10.

[0043] 10(b) includes a lead frame 101A, a semiconductor chip 110, a bonding member 125, and a resin part 140. The lead frame 101A is obtained by dividing the lead frame 10A into individual pieces, and is the part inside the individual region R of the lead frame 10A. The lead frame 101A includes leads 12.

[0044] The semiconductor chip 110 is flip-chip mounted face-down on the upper surface 12b of the lead 12. The electrode terminals 115 of the semiconductor chip 110 are electrically connected to the upper surface 12b of the lead 12 via bonding members 125 such as solder bumps.

[0045] The resin part 140 is provided on the lead frame 101A. The resin part 140 covers at least the semiconductor chip 110, the bonding member 125, the upper surface 12b of the lead 12, the side surface 12d of the lead 12, and the stepped surface 12c of the lead 12. The resin part 140 exposes the lower surface 12a and the outer surface 12e of the lead 12. When viewed from a direction perpendicular to the side surface of the resin part 140, the stepped surface 12c is convex toward the upper surface. The lower surface 12a and / or the outer surface 12e of the lead 12 can be used, for example, as an external connection terminal.

[0046] As described above, the lead frame according to the present invention does not need to have a die pad or a support bar. In the semiconductor device 100A, similar to the semiconductor device 100, the step surface 12c is convex upward, so burrs are less likely to occur on the cut surfaces of the leads 12, and adjacent leads 12 are less likely to be short-circuited. Also, similar to the semiconductor device 100, peeling between the leads 12 and the resin portion 140 is less likely to occur. These features improve the reliability of the semiconductor device 100A.

[0047] (Variation 2) In the second modification, an example is shown in which a recess is provided in a frame portion located between adjacent leads in a top view.

[0048] Fig. 11 is a top view illustrating the vicinity of an individual region of a lead frame according to Modification 2, with Fig. 11(a) showing the entire individual region and Fig. 11(b) showing an enlarged view of part P in Fig. 11(a). Fig. 12 is a cross-sectional view illustrating the vicinity of an individual region of a lead frame according to Modification 2, with Fig. 12(a) showing a cross-section along line BB in Fig. 11(b), Fig. 12(b) showing a cross-section along line CC in Fig. 11(b), and Fig. 12(c) showing a cross-section along line DD in Fig. 11(b).

[0049] As shown in FIGS. 11 and 12, in a lead frame 10B, in a top view, the leads 12 have protrusions 12f that protrude toward the step surface 12c. In a top view, the sides of the protrusions 12f on the step surface 12c side are curved in an R-shape. In the lead frame 10B, the width of the step surface 12c is narrower than the width of the top surface 12b. In a top view, the side of the frame 11 that intersects with the leads 12 on the step surface 12c side is linear. In a top view, the frame 11 has recesses 11f between adjacent leads 12 that are recessed in the direction opposite to the protruding direction of the leads 12. Both ends of the recesses 11f in the X-axis direction are, for example, rounded.

[0050] The cross-sectional shape shown in FIG. 12(a) is the same as the cross-sectional shape shown in FIG. 4(b). The cross-sectional shape shown in FIG. 12(b) is the same as the cross-sectional shape shown in FIG. 4(c). In the cross section shown in FIG. 12(c), the lower surface 11a of the frame portion 11 is flat. The upper surfaces 11b of the frame portion 11 located on both sides of the recess 11f are convex in directions away from the lower surface 11a. The upper surfaces 11b of the frame portion 11 located on both sides of the recess 11f are, for example, R-shaped, with the highest part in the center in the X-axis direction and the height gradually decreasing from the center to the periphery in the X-axis direction.

[0051] Figure 13 is a top view illustrating a method for fabricating the shape shown in Figure 11(b), and Figure 14 is a bottom view illustrating a method for fabricating the shape shown in Figure 11(b).

[0052] To produce the shape shown in FIG. 11(b), first, as shown in FIGS. 13(a) and 14(a), a resist layer 330 is formed on the upper surface of the plate material 10S, and a resist layer 340 is formed on the lower surface. The resist layer 330 has an opening 330x that opens an area where the step surface 12c will be formed, and has protruding portions 330a and 330b that face each other across the opening 330x. The resist layer 340 has a covering portion 340a that covers a position that overlaps with the opening 330x in a top view. A width W1 of the protruding portions 330a and 330b of the resist layer 330 is equal to a width W2 of the covering portion 340a of the resist layer 340.

[0053] Next, as shown in Figures 13(b) and 14(b), the plate material 10S is etched using the resist layers 330 and 340 as an etching mask. Next, as shown in Figures 13(c) and 14(c), the resist layers 330 and 340 are removed to produce the shape shown in Figure 11(b). Recesses 11f are formed on both sides of the protrusion 330a in the X-axis direction. Furthermore, protrusions 12f are formed at positions corresponding to the protrusion 330b.

[0054] In this way, when viewed from above, the frame 11 has recesses 11f between adjacent leads 12 that are recessed in the opposite direction to the protruding direction of the leads 12, thereby preventing the occurrence of side edges between adjacent leads 12. If side edges occur, the contact area between the blade and the step surface increases when cutting the plate material, making burrs more likely to occur. On the other hand, by preventing the occurrence of side edges, burrs are less likely to occur between adjacent leads 12.

[0055] The side edge between adjacent leads 12 refers to a portion where etching is insufficient between adjacent leads 12, forming a mountain-like portion, as shown by the arrow in FIG.

[0056] (Variation 3) In the third modification, a protrusion is provided on the frame at a position where the frame intersects with the leads when viewed from above.

[0057] Fig. 16 is a top view illustrating the vicinity of an individual region of a lead frame according to Modification 3, with Fig. 16(a) showing the entire individual region and Fig. 16(b) showing an enlarged view of part P in Fig. 16(a). Fig. 17 is a cross-sectional view illustrating the vicinity of an individual region of a lead frame according to Modification 3, with Fig. 17(a) showing a cross-section along line BB in Fig. 16(b), Fig. 17(b) showing a cross-section along line CC in Fig. 16(b), and Fig. 17(c) showing a cross-section along line DD in Fig. 16(b).

[0058] 16 and 17, in a lead frame 10C, in a top view, the lead 12 has a protrusion 12g that protrudes toward the step surface 12c. In a top view, the side of the protrusion 12g facing the step surface 12c is curved in an R-shape. In the lead frame 10C, the width of the step surface 12c is narrower than the width of the upper surface 12b.

[0059] Furthermore, in a top view, frame 11 has protrusions 11g at positions where it intersects with leads 12, protruding in the direction in which leads 12 protrude. That is, in a top view, protrusions 11g are provided at positions facing protrusions 12g across step surface 12c. In a top view, the side of protrusions 11g on the step surface 12c side is curved in an R-shape. Frame 11 may have linear regions on both sides of protrusions 11g at positions where it intersects with leads 12.

[0060] The cross-sectional shape shown in FIG. 17(a) is the same as the cross-sectional shape shown in FIG. 4(b). The cross-sectional shape shown in FIG. 17(b) is the same as the cross-sectional shape shown in FIG. 4(c). In the cross section shown in FIG. 17(c), the lower surface 11a of the frame portion 11 is flat. The upper surface of the convex portion 11g is convex in a direction away from the lower surface 11a. For example, the upper surface of the convex portion 11g is highest in the central portion in the X-axis direction, and the height gradually decreases as it moves from the central portion to the periphery in the X-axis direction. The upper surface of the convex portion 11g is curved in an R-shape. The upper surface of the convex portion 11g may have a shape including a first curved portion that is curved entirely in the width direction and a second curved portion that protrudes from near the center of the first curved portion.

[0061] FIG. 18 is a top view illustrating a method for fabricating the shape shown in FIG. 16(b). FIG. 19 is a bottom view illustrating a method for fabricating the shape shown in FIG. 16(b). To fabricate the shape shown in FIG. 16(b), first, as shown in FIGS. 18(a) and 19(a), a resist layer 350 is formed on the top surface of the plate material 10S, and a resist layer 360 is formed on the bottom surface. The resist layer 350 has an opening 350x that opens an area where the step surface 12c will be formed, and has convex portions 350a and 350b that face each other across the opening 350x. The resist layer 360 has a covering portion 360a that covers a position that overlaps with the opening 350x in a top view. A width W3 of the convex portions 350a and 350b of the resist layer 350 is narrower than a width W4 of the covering portion 360a of the resist layer 360.

[0062] Next, as shown in Figures 18(b) and 19(b), the plate material 10S is etched using the resist layers 350 and 360 as an etching mask. Next, as shown in Figures 18(c) and 19(c), the resist layers 350 and 360 are removed to produce the shape shown in Figure 16(b). Protrusions 11g and 12g are formed at positions corresponding to the protrusions 350a and 350b.

[0063] In this way, when viewed from above, the frame 11 has the convex portions 11g at positions where the frame 11 intersects with the leads 12, protruding in the direction in which the leads 12 protrude, thereby preventing the occurrence of side edges between adjacent leads 12. As described above, side edges can be a cause of burrs, so by preventing the occurrence of side edges, burrs are less likely to occur between adjacent leads 12.

[0064] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0065] 10, 10A, 10B, 10C, 101, 101A lead frame 101,102,103 area 10S plate material 11 Frame 11a,12a,13a,14a Bottom surface 11b,12b,13b,14b Top surface 11f Recess 11g, 12f, 12g convex part 12 Leads 12c step surface 12d side 12e External surface 13 Die pad 13c 2nd step surface 14 Support bar 100,100A semiconductor device 110 Semiconductor Chips 115 Electrode terminal 120 Adhesive 125 Joint materials 130 Metal Wire 140 Resin part 310,320,330,340,350,360 Resist layer 310x,320x,330x,350x opening 330a, 330b, 350a, 350b convex part 340a, 360a Covering part 400 Blade

Claims

1. A frame portion and a plurality of leads protruding from an inner edge of the frame portion toward the inside of the frame portion; The lead The underside and an upper surface opposite the lower surface; a step surface recessed from the upper surface toward the lower surface, In a vertical cross section taken through the step surface and perpendicular to the direction in which the leads protrude, the step surface is convex toward the upper surface.

2. 2. The lead frame according to claim 1, wherein in a vertical cross section taken through the step surface and parallel to a direction in which the leads protrude, the step surface is parallel to the lower surface.

3. 2. The lead frame of claim 1, wherein in a cross section taken through the lower surface and the upper surface and perpendicular to the direction in which the leads protrude, the side surface connecting the lower surface and the upper surface has a central portion in the thickness direction that protrudes laterally beyond the lower surface and the upper surface.

4. The lead frame according to claim 1 , wherein the width of the step surface is equal to the width of the top surface.

5. The lead frame according to claim 1 , wherein, in a top view, the frame portion has recesses between adjacent leads that are recessed in a direction opposite to a direction in which the leads protrude.

6. The lead frame according to claim 1 , wherein the frame has, in a top view, a protrusion at a position where the frame intersects with the lead, the protrusion protruding in a direction in which the lead protrudes.

7. The lead frame according to claim 5 , wherein the width of the step surface is narrower than the width of the top surface.

8. an upper surface of the frame portion is flush with an upper surface of the lead; 3. The lead frame according to claim 1, wherein a lower surface of said frame portion is flush with lower surfaces of said leads.

9. providing a first resist layer on an upper surface of a metal plate and a second resist layer on a lower surface of the metal plate; and forming a frame portion and a plurality of leads by etching the plate material through the first resist layer and the second resist layer, the leads protruding from an inner edge of the frame portion toward the inside of the frame portion and including a lower surface, an upper surface opposite the lower surface, and a stepped surface recessed from the upper surface toward the lower surface, In the step of providing the first resist layer and the second resist layer, a region where only the second resist layer is provided is formed in a top view, In the etching step, the region is half-etched from the top surface side to form the step surface, and in a cross section taken through the step surface and perpendicular to the direction in which the leads protrude, the step surface is convex toward the top surface.

10. a plurality of leads each having a lower surface, an upper surface opposite to the lower surface, a stepped surface recessed from the upper surface toward the lower surface, and an outer surface connecting the lower surface and the stepped surface; a semiconductor chip electrically connected to the leads; a resin portion that covers the semiconductor chip, the upper surface, and the stepped surface and exposes the lower surface and the outer surface, When viewed from a direction perpendicular to the side surface of the resin portion, the step surface is convex toward the upper surface.

Images