Lead frame, method for manufacturing lead frame, and semiconductor device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SHINKO ELECTRIC IND CO LTD
- Filing Date
- 2023-10-03
- Publication Date
- 2026-06-17
AI Technical Summary
The increased integration of semiconductor elements on lead frames leads to higher inner lead density, resulting in burrs during the cutting of connection portions, which can cause short circuits between adjacent inner leads, thereby decreasing the yield of lead frames.
The lead frame design features inner leads with specific surface configurations, including a first main surface, an end surface, and side surfaces, where the angle between certain virtual straight lines intersecting these surfaces is less than 90 degrees, and the inner lead side surfaces are positioned in a way to reduce the occurrence of burrs during cutting.
This design effectively suppresses the occurrence of burrs and short circuits between inner leads, thereby improving the yield of lead frames by reducing defects during the manufacturing process.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present disclosure relates to a lead frame, a method for manufacturing a lead frame, and a semiconductor device. [Background technology]
[0002] Conventionally, when manufacturing a lead frame having inner leads, a plurality of inner leads are formed by wet etching a metal plate, and the ends of the inner leads are connected by connecting parts. Then, after forming a plating film or the like, the connecting parts are cut off. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-055948 [Patent Document 2] JP 10-056118 A Summary of the Invention [Problem to be solved by the invention]
[0004] As semiconductor elements mounted on lead frames become more highly integrated, the density of inner leads is increasing, and when the connecting parts are cut, burrs may be generated, which may cause short circuits between adjacent inner leads. The occurrence of short circuits leads to a decrease in the yield of lead frames.
[0005] An object of the present disclosure is to provide a lead frame, a manufacturing method of a lead frame, and a semiconductor device that can suppress a decrease in yield. [Means for solving the problem]
[0006] According to one embodiment of the present disclosure, a lead frame is provided having a plurality of inner leads arranged in a first direction, the inner lead having a first main surface parallel to the first direction, an end face connected to the first main surface, a first side surface connected to the first main surface and the end face, and a second side surface connected to the first main surface and the first side face, wherein, in a plan view perpendicular to the first main surface, an angle between a first virtual line including a first intersection line between the first main surface and the end face and a second virtual line including a second intersection line between the first main surface and the second side face is less than 90 degrees on the inner lead side, and a third intersection line between the first main surface and the first side face is on the inner lead side of the first virtual line and the second virtual line. Effect of the Invention
[0007] According to the disclosed technique, a decrease in yield can be suppressed. [Brief description of the drawings]
[0008] [Figure 1] FIG. 2 is a diagram illustrating an example of an outline of a lead frame according to the first embodiment. [Diagram 2] FIG. 2 is a top view illustrating the lead frame according to the first embodiment. [Diagram 3] FIG. 3 is an enlarged view of a portion of FIG. 2. [Figure 4] 1 is a cross-sectional view illustrating a lead frame according to a first embodiment. [Diagram 5] 1A to 1C are top views illustrating the method for manufacturing the lead frame according to the first embodiment; [Figure 6] 1A to 1C are cross-sectional views (part 1) illustrating the method for manufacturing the lead frame according to the first embodiment. [Figure 7] 5A to 5C are cross-sectional views (part 2) illustrating the method for manufacturing the lead frame according to the first embodiment. [Figure 8] 5A to 5C are top views (part 2) illustrating the method for manufacturing the lead frame according to the first embodiment. [Figure 9] 6A to 6C are top views (part 3) illustrating the method for manufacturing the lead frame according to the first embodiment. [Figure 10] 5A to 5C are cross-sectional views (part 3) illustrating the method for manufacturing the lead frame according to the first embodiment. [Figure 11] 4A to 4C are cross-sectional views illustrating the method for manufacturing the lead frame according to the first embodiment; [Figure 12] 1A to 1C are top views illustrating a method for manufacturing a lead frame according to a reference example; [Figure 13] 11A to 11C are top views (part 2) illustrating the manufacturing method of the lead frame according to the reference example. [Figure 14] 1A to 1C are cross-sectional views (part 1) illustrating a method for manufacturing a lead frame according to a reference example. [Figure 15] 11A to 11C are cross-sectional views (part 2) illustrating the method for manufacturing a lead frame according to a reference example. [Figure 16] 10 is a cross-sectional view illustrating a semiconductor device according to a second embodiment. [Figure 17] 6A to 6C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to a second embodiment. [Figure 18] 13A to 13C are top views illustrating a method for manufacturing a lead frame according to a third embodiment. [Figure 19] 10A to 10C are cross-sectional views illustrating a method for manufacturing a lead frame according to a third embodiment. [Figure 20] 13A to 13C are top views illustrating a method for manufacturing a lead frame according to a fourth embodiment. [Figure 21] 13A to 13C are top views illustrating a method for manufacturing a lead frame according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration may be denoted by the same reference numerals to avoid redundant description. In the following description, an XYZ orthogonal coordinate system is used, and the +Z side may be referred to as the upper side, upper side, or top, and the -Z side may be referred to as the lower side, lower side, or bottom, as viewed from any point. The lower surface may be referred to as one surface or bottom surface, and the upper surface may be referred to as the other surface or top surface. However, this coordinate system is defined for the purpose of explanation and does not limit the posture of the lead frame and the semiconductor device. The lead frame and the semiconductor device may be used upside down or may be arranged at any angle. In addition, a planar view refers to viewing an object from the normal direction of one surface of the lead frame or the semiconductor device, and a planar shape refers to the shape of an object viewed from the normal direction of one surface of the lead frame or the semiconductor device.
[0010] (First embodiment) First, a first embodiment will be described. The first embodiment relates to a lead frame. The lead frame according to the first embodiment is a lead frame on which a semiconductor element is mounted and which is covered with a sealing resin to become a semiconductor device.
[0011] [Lead frame structure] The structure of the lead frame according to the first embodiment will be described. FIG. 1 is a diagram illustrating an outline of the lead frame according to the first embodiment. FIG. 2 is a top view illustrating the lead frame according to the first embodiment. FIG. 3 is a diagram illustrating an enlarged portion (area 21 surrounded by a two-dot chain line) in FIG. 2. FIG. 3(a) is a top view, and FIG. 3(b) is a cross-sectional view. FIG. 3(b) corresponds to the cross-sectional view taken along line IIIb-IIIb in FIG. 3(a). FIG. 4 is a cross-sectional view illustrating the lead frame according to the first embodiment. FIG. 4 corresponds to the cross-sectional view taken along line IV-IV in FIG. 2.
[0012] As shown in FIG. 1 to FIG. 3, the lead frame 1 according to the first embodiment has a structure in which a plurality of singulation regions 10 are connected via a frame portion 20. For example, the singulation region 10 has a rectangular planar shape. The frame portion 20 is provided outside each singulation region 10, and has a portion formed in a frame shape on the outer edge of the lead frame 1 and a portion formed in a straight line between adjacent singulation regions 10. FIG. 2 shows one singulation region 10 and the frame portion 20 surrounding it. As shown in FIG. 4, the lead frame 1 includes a metal plate 100. For example, copper (Cu), a Cu alloy, a 42 alloy, etc. can be used as the material of the metal plate 100. The thickness of the lead frame 1 can be, for example, about 100 μm to 300 μm.
[0013] Each singulation region 10 has a die pad 400, an inner lead 200, an outer lead 300, a dam bar 600, and a support bar 700. The dam bar 600 is arranged in a rectangular ring shape along the frame portion 20 in each singulation region 10 so as to surround the die pad 400. The support bar 700 is arranged obliquely in each singulation region 10.
[0014] The four corners of dam bar 600 are connected to the four corners of frame portion 20. Dam bar 600 is provided with a plurality of inner leads 200 and outer leads 300. The inner leads 200 extend from dam bar 600 towards die pad 400, and the outer leads 300 extend from dam bar 600 on the opposite side to the inner leads 200. One end of support bar 700 is connected to frame portion 20 and the other end is connected to the four corners of die pad 400, and supports die pad 400.
[0015] As shown in FIG. 4, the die pad 400 has a main surface 410 on which a semiconductor element is mounted, and a main surface 420 opposite to the main surface 410. The main surfaces 410 and 420 are parallel to the XY plane. The die pad 400 has four side surfaces 430 connected to the main surfaces 410 and 420. Each side surface 430 has a concave surface 431 formed on the +Z side in the thickness direction of the metal plate 100, and a concave surface 432 formed on the -Z side. Each side surface 430 has unevenness associated with the concave surfaces 431 and 432, but two side surfaces 430 are approximately parallel to the YZ plane, and the other two side surfaces 430 are approximately parallel to the ZX plane.
[0016] A plurality of inner leads 200 are provided on each of the +X side, -X side, +Y side, and -Y side of the die pad 400. The multiple inner leads on the +X side or -X side of the die pad 400 are aligned in the Y-axis direction, and the multiple inner leads on the +Y side or -Y side of the die pad 400 are aligned in the X-axis direction.
[0017] A plating film 291 and an adhesive tape 292 are provided on the surface of the +Z side of the inner lead 200. The plating film 291 is provided for each inner lead 200 near the end of the inner lead 200. The plating film 291 is, for example, a silver (Ag) film, a gold (Au) film, a nickel (Ni) / Au film (a metal film formed by laminating a Ni film and a Au film in this order), a Ni / Pd / Au film (a metal film formed by laminating a Ni film, a Pd film, and a Au film in this order), or the like. The adhesive tape 292 is provided in a ring shape between the plating film 291 of each inner lead 200 and the dam bar 600. The adhesive tape 292 is provided to suppress deformation such as bending of the inner lead 200. Note that the plating film 291 or the adhesive tape 292, or both of them may not be provided. In FIG. 3, the plating film 291 and the adhesive tape 292 are omitted.
[0018] Here, the multiple inner leads 200 on the +Y side of the die pad 400 will be described in detail. As shown in FIG. 3, the inner lead 200 has main surfaces 210 and 220 parallel to the XY plane. The main surfaces 210 and 220 are parallel to the X-axis direction and the Y-axis direction. For example, the main surface 210 is flush with the main surface 410, and the main surface 220 is flush with the main surface 420. A plating film 291 and an adhesive tape 292 are provided on the main surface 210, and a bonding wire 44 (see FIG. 16) is connected to the main surface 210. The main surface 210 is an example of a first main surface, and the main surface 220 is an example of a second main surface.
[0019] The inner lead 200 has an end face 230. The end face 230 faces a side surface 430 on the +Y side of the die pad 400. The end face 230 is continuous with the main surfaces 210 and 220. As described below, the end face 230 is formed by punching, and the angle between the end face 230 and the main surfaces 210 and 220 is approximately 90 degrees. The end faces 230 between the multiple inner leads 200 are flush with each other.
[0020] The inner lead 200 has side surfaces 240 and 250. The side surface 240 is continuous with the main surfaces 210 and 220 and the end surface 230. For example, the side surface 240 is formed closer to the die pad 400 than the portion of the main surface 210 where the plating film 291 (see FIG. 2) is formed. The side surface 240 may be formed from the end surface 230 to the immediate vicinity of the portion of the main surface 210 where the plating film 291 is formed. The side surface 240 may be formed from the end surface 230 to the portion of the main surface 210 where the plating film 291 is formed. The side surface 240 has a concave surface 241 formed on the +Z side in the thickness direction of the metal plate 100 and a concave surface 242 formed on the -Z side. The concave surface 241 and the concave surface 242 are connected, and a pointed protrusion 243 exists at the boundary between them. The protrusion 243 is, for example, on the +Z side from the center of the thickness direction of the metal plate 100. The side surface 250 is continuous with the main surfaces 210 and 220 and the side surface 240. Although not shown in the figure, the side surface 250 has a concave surface formed on the +Z side in the thickness direction of the metal plate 100 and a concave surface formed on the -Z side. These two concave surfaces are connected to each other, and a sharp protrusion exists at the boundary between them. This protrusion is, for example, on the +Z side of the center in the thickness direction of the metal plate 100. The side surface 240 is an example of a first side surface, and the side surface 250 is an example of a second side surface.
[0021] The inner lead 200 has a side surface 270. The side surface 270 is continuous with the main surfaces 210 and 220, and is continuous with the end surface 230 on the side opposite to the side surface 240. The side surface 270 has a concave surface 271 formed on the +Z side in the thickness direction of the metal plate 100, and a concave surface 272 formed on the -Z side. The concave surfaces 271 and 272 are connected, and a pointed protrusion 273 exists at the boundary between them. The protrusion 273 is, for example, on the +Z side of the center in the thickness direction of the metal plate 100. The side surface 270 is an example of a fourth side surface.
[0022] In a plan view perpendicular to the main surface 210, an angle θ1 between a virtual line L1 including an intersection line 235 between the main surface 210 and the end surface 230 and a virtual line L2 including an intersection line 255 between the main surface 210 and the side surface 250 is less than 90 degrees on the inner lead 200 side. In addition, an intersection line 245 between the main surface 210 and the side surface 240 is on the inner lead 200 side of the virtual lines L1 and L2. For example, the intersection line 245 is a curved line recessed toward the inside of the inner lead 200. The angle θ1 may be larger for the inner lead 200 located closer to the center in the X-axis direction. The virtual line L1 is an example of a first virtual line, and the virtual line L2 is an example of a second virtual line. The intersection line 235 is an example of a first intersection line, the intersection line 255 is an example of a second intersection line, and the intersection line 245 is an example of a third intersection line.
[0023] In a plan view perpendicular to the main surface 210, the angle θ2 between the virtual line L1 and the virtual line L3 including the intersection line 275 between the main surface 210 and the side surface 270 is 90 degrees or more on the inner lead 200 side. The angle θ2 may be smaller for the inner lead 200 located closer to the center in the X-axis direction. The virtual line L3 is an example of a third virtual line. The intersection line 275 is an example of a fourth intersection line.
[0024] The width of the inner lead 200 may vary in the longitudinal direction. For example, the width of the inner lead 200 may increase as it moves away from the die pad 400. Within a range including the side surface 250 in the longitudinal direction, the width of the inner lead 200 may be wider at the main surface 210 than at the main surface 220. The width of the inner lead 200 means the dimension in the short direction perpendicular to the longitudinal direction at each position in the longitudinal direction.
[0025] The multiple inner leads 200 on the -Y side of the die pad 400 have a configuration in which, for example, the multiple inner leads 200 on the +Y side of the die pad 400 are rotated 180 degrees around the center of the die pad 400 as the rotation axis. Also, the multiple inner leads 200 on the +X side or -X side of the die pad 400 have a configuration in which, for example, the multiple inner leads 200 on the +Y side of the die pad 400 are rotated 90 degrees clockwise or counterclockwise around the center of the die pad 400 as the rotation axis.
[0026] [Lead frame manufacturing method] Next, a method for manufacturing the lead frame 1 according to the first embodiment will be described. FIG. 5 is a top view illustrating the method for manufacturing the lead frame according to the first embodiment. FIGS. 6 to 7 are cross-sectional views illustrating the method for manufacturing the lead frame according to the first embodiment. FIGS. 8 to 9 are top views illustrating the change in a part (region 501 surrounded by a two-dot chain line) in FIG. 5, illustrating the method for manufacturing the lead frame according to the first embodiment. FIGS. 10 to 11 are cross-sectional views illustrating the method for manufacturing the lead frame according to the first embodiment. FIGS. 6 to 7 show the change in the cross section taken along line VIa-VIa in FIG. 5. FIGS. 10 to 11 show the change in the cross section taken along line Xa-Xa in FIG. 8(a). Region 501 in FIG. 5 corresponds to region 21 in FIG. 2.
[0027] First, as shown in Fig. 6(a), a metal plate 100 made of metal and having a predetermined shape is prepared. The material of the metal plate 100 may be, for example, copper, a copper alloy, or a 42 alloy. The thickness of the metal plate 100 may be, for example, about 100 µm to 300 µm. The metal plate 100 has one main surface 110 and the other main surface 120.
[0028] Next, as shown in Fig. 6(b), Fig. 8(a) and Fig. 10(a), a photosensitive resist 810 is formed on the main surface 110 of the metal plate 100, and a photosensitive resist 820 is formed on the main surface 120 of the metal plate 100. The resists 810 and 820 may be formed, for example, by applying and drying a resist liquid, or by attaching a resist film. As the resists 810 and 820, for example, a dry film resist such as an epoxy resin or an acrylic resin, an electrodeposition resist, or the like may be used.
[0029] Next, the resist 810 is exposed and developed to form a coating pattern 811 and an opening 812 in the resist 810, and the resist 820 is exposed and developed to form a coating pattern 821 and an opening 822 in the resist 820. The coating pattern 811 covers the portions of the main surface 110 where the frame 20, the inner lead 200, the outer lead 300, the die pad 400, the connecting portion 500 (see FIG. 5), the dam bar 600, and the support bar 700 are to be formed. The opening 812 is a portion for forming an opening in the metal plate 100, and the remaining portion of the main surface 110 is exposed from the opening 812. The coating pattern 821 covers the portions of the main surface 120 where the frame 20, the inner lead 200, the outer lead 300, the die pad 400, the connecting portion 500, the dam bar 600, and the support bar 700 are to be formed. The opening 822 is a portion for forming an opening in the metal plate 100, and the remaining portion of the main surface 120 is exposed from the opening 822. In a region forming a portion including the side surface 250 in the longitudinal direction of the inner lead 200, the width of the covering pattern 811 is made wider than the width of the covering pattern 821, and the width of the opening 812 is made narrower than the width of the opening 822.
[0030] The coating pattern 811 and the opening 812 of the resist 810 and the coating pattern 821 and the opening 822 of the resist 820 include four connection part patterns for forming the connection part 500. One of the connection parts 500 has a longitudinal direction in the X-axis direction and connects the ends of the multiple inner leads 200 formed on the +Y side of the die pad 400. The other connection part 500 has a longitudinal direction in the Y-axis direction and connects the ends of the multiple inner leads 200 formed on the +X side of the die pad 400. Still another connection part 500 has a longitudinal direction in the X-axis direction and connects the ends of the multiple inner leads 200 formed on the -Y side of the die pad 400. The remaining connection part 500 has a longitudinal direction in the Y-axis direction and connects the ends of the multiple inner leads 200 formed on the -X side of the die pad 400. The four connection part patterns are formed so that these four connection parts 500 are formed.
[0031] The connecting portion 500 is later removed by cutting the metal plate 100, but the cutting line CL at the time of cutting overlaps the end face 230 of the inner lead 200 in a plan view. The coating pattern 811 and the opening 812 are formed so that the angle θ1 between the imaginary straight lines L1 and L2 is less than 90 degrees on the inner lead 200 side, and the intersection line 245 is located on the inner lead 200 side of the imaginary straight lines L1 and L2 (see FIG. 3(a)). For example, the coating pattern 811 includes a recess 814 for forming the side surface 240, as shown in FIG. 8(a). The recess 814 intersects with the cutting line CL.
[0032] Next, as shown in Fig. 6(c), Fig. 8(b), and Fig. 10(b), half-etching of the metal plate 100 is performed from the main surface 110 side and the main surface 120 side of the metal plate 100 using the resists 810 and 820 as etching masks. The half-etching of the metal plate 100 is wet etching. When the metal plate 100 is made of copper, for example, an aqueous solution of ferric chloride or cupric chloride can be used as an etching solution in the half-etching of the metal plate 100.
[0033] As a result, the frame portion 20, the inner leads 200, the outer leads 300, the die pad 400, the connecting portions 500, the dam bar 600, and the support bar 700 are formed on the metal plate 100. At this time, the side surfaces 240 are formed so as to intersect with the cutting line CL. Also, as shown in Fig. 6(c), each connecting portion 500 has a side surface 530 facing the side surface 430 of the die pad 400. Each side surface 530 has a concave surface 531 formed on the +Z side in the thickness direction of the metal plate 100, and a concave surface 532 formed on the -Z side.
[0034] 5, 7(a), 9(a) and 11(a), the resists 810 and 820 are removed. The resists 810 and 820 can be removed by, for example, a remover.
[0035] 7(b), a plating film 291 is formed on the main surface 210 of the inner lead 200, and an adhesive tape 292 is attached. The plating film 291 can be formed by, for example, an electrolytic plating method. In FIG. 9, the plating film 291 and the adhesive tape 292 are omitted.
[0036] Next, as shown in Fig. 7(c) and Fig. 9(b), the metal plate 100 is cut along the cutting line CL to remove the connecting portion 500 and the tip portion of the inner lead 200. In this cutting, for example, a punching process using a die is performed. At this time, as shown in Fig. 11(b), no burrs are generated on the cut surface or its vicinity.
[0037] In this manner, the lead frame 1 can be manufactured.
[0038] [Effect of lead frame] Next, the effect of the lead frame 1 will be described with reference to a reference example. Figures 12 and 13 are top views illustrating a method for manufacturing a lead frame according to a reference example. Figures 14 and 15 are cross-sectional views illustrating a method for manufacturing a lead frame according to a reference example. Figures 14 and 15 show changes in a cross section taken along line XIVa-XIVa in Figure 12(a).
[0039] The lead frame 1X according to the reference example differs from the lead frame 1 in that the inner lead 200 does not have a side surface 240, and the side surface 250 is directly connected to the end surface 230, as shown in FIGS. 13(b) and 15(b).
[0040] 12(a) and 14(a), in manufacturing the lead frame 1X, a coating pattern 811X and an opening 812X are formed in a resist 810, instead of the coating pattern 811 and the opening 812. The coating pattern 811X does not include a recess 814, as shown in FIG.
[0041] After forming a coating pattern 811X and an opening 812X in the resist 810 and forming a coating pattern 821 and an opening 822 in the resist 820, half-etching of the metal plate 100 is performed from the main surface 110 side and the main surface 120 side of the metal plate 100 using the resists 810 and 820 as etching masks, as shown in Figures 12(b) and 14(b).
[0042] As a result, the frame portion 20, the inner leads 200X, the outer leads 300, the die pad 400, the connecting portion 500X, the dam bar 600, and the support bar 700 are formed on the metal plate 100. The inner leads 200X and the connecting portion 500X differ from the inner leads 200 and the connecting portion 500 in that they do not have a side surface 240 at their boundary.
[0043] 13(a) and 15(a), the resists 810 and 820 are removed. Next, similarly to the first embodiment, a plating film 291 is formed, and an adhesive tape 292 is attached (see FIG. 7(b)).
[0044] Next, as shown in FIG. 13(b), the metal plate 100 is cut along the cutting line CL to remove the connecting portion 500X and the tip portion of the inner lead 200X. In this cutting, for example, a punching process using a die is performed. In the reference example, the side surface 240 is not formed, and the side surface 250 is directly connected to the end surface 230. Therefore, compared with the first embodiment, the area of the metal plate 100 that is sheared during cutting is large, and the volume of the metal plate 100 that is processed during cutting is large. Therefore, burrs 50 are likely to occur during cutting. In particular, since burrs are generally more likely to occur in sharper parts, as shown in FIG. 13(b) and FIG. 15(b), burrs 50 are likely to occur from the convex portion 253X of the side surface 250, and may connect to the convex portion 273X of the opposing side surface 270. In this case, a short circuit occurs via the burr 50.
[0045] In contrast, in this embodiment, the coating pattern 811 is provided with recesses 814, which reduces the area and amount of shear processing of the metal plate 100 during cutting, and also reduces sharp edges, thereby suppressing the generation of burrs during cutting. This makes it possible to suppress short circuits between the inner leads and improve the yield of the lead frame.
[0046] Second embodiment Next, a second embodiment will be described. The second embodiment relates to a semiconductor device manufactured using the lead frame 1.
[0047] [Structure of semiconductor device] A description will now be given of the structure of the semiconductor device according to the second embodiment. Fig. 16 is a cross-sectional view illustrating the semiconductor device according to the second embodiment.
[0048] The semiconductor device 2 according to the second embodiment has a die pad 400, an inner lead 200, an outer lead 300, a semiconductor element 40, a bonding wire 44, and a sealing resin 48. The dam bar 600 and the frame portion 20 are cut off from the lead frame 1.
[0049] The semiconductor element 40 has a base 41 and a plurality of electrodes 42 provided on the upper surface of the base 41. The semiconductor element 40 is mounted on a die pad 400. The lower surface of the base 41 is bonded to a main surface 410 of the die pad 400 by an adhesive 46. As the adhesive 46, a die attach film, a silver paste, a solder, or the like is used. The bonding wire 44 electrically connects the plating film 291 and the electrode 42. The sealing resin 48 seals the semiconductor element 40, the bonding wire 44, the die pad 400, and the inner lead 200. The sealing resin 48 is, for example, a so-called mold resin made of epoxy resin containing a filler. The outer lead 300 is located outside the sealing resin 48. The outer lead 300 is bent so as to be easily connected to, for example, a mounting board.
[0050] [Method of manufacturing semiconductor device] Next, a method for manufacturing the semiconductor device 2 according to the second embodiment will be described. Figure 17 is a cross-sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment.
[0051] 17(a), a lead frame 1 is prepared, and a semiconductor element 40 is mounted on a die pad 400. At this time, the lower surface of a base 41 is bonded to a main surface 410 of the die pad 400 with an adhesive 46. Next, a plating film 291 and an electrode 42 are electrically connected using a bonding wire 44.
[0052] 17(b), the semiconductor element 40, the bonding wires 44, the die pad 400 and the inner leads 200 are sealed with a sealing resin 48. The sealing resin 48 can be formed by, for example, a transfer molding method or a compression molding method.
[0053] Next, dam bar 600 and frame portion 20 are cut off from lead frame 1, and outer leads 300 are bent into a prescribed shape (see FIG. 16).
[0054] In this manner, the semiconductor device 2 according to the second embodiment can be manufactured.
[0055] The semiconductor device 2 is manufactured using the lead frame 1, which can prevent short circuits between the inner leads 200. The semiconductor device 2 may be manufactured using a lead frame 3, 4, or 5 described below.
[0056] Note that the semiconductor element 40 may be mounted on the lead frame 1 by flip-chip connection using solder bumps instead of connection using bonding wires 44. In this case, for example, solder bumps are provided on the electrodes 42 of the semiconductor element 40, and the solder bumps are connected to the plating film 291 of the lead frame 1. When the semiconductor element 40 is mounted on the lead frame 1 by flip-chip connection, the lead frame 1 does not need to include the die pad 400.
[0057] Third embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment mainly in the shape of the end of the inner lead 200. Here, the structure of the lead frame according to the third embodiment will be described based on a method for manufacturing the lead frame. FIG. 18 is a top view illustrating a method for manufacturing the lead frame according to the third embodiment. FIG. 19 is a cross-sectional view illustrating a method for manufacturing the lead frame according to the third embodiment. FIG. 19 shows a change in a cross section taken along line XIXa-XIXa in FIG. 18(a).
[0058] In manufacturing the lead frame 3, the coating pattern and the opening formed in the resist 810 are changed from the coating pattern 811 and the opening 812. Specifically, the coating pattern and the opening shape of the resist 810 are changed so that the shape of the inner lead 200 becomes the shape shown in FIG. 18(b). As shown in FIG. 18(b), in the lead frame 3, the intersection line 245 is located on the inner lead 200 side of the virtual straight lines L1 and L2. At the same time, the inner lead 200 has the main surfaces 210 and 220 and the side surface 260 continuing to the end surface 230 and the side surface 270, and is formed so that the intersection line 265 between the main surface 210 and the side surface 260 is located on the inner lead 200 side of the virtual straight lines L1 and L3. For example, the intersection line 265 is a curved line recessed toward the inside of the inner lead 200. For example, the side surface 260 is formed closer to the die pad 400 than the portion of the main surface 210 where the plating film 291 (see FIG. 2) is formed. The side surface 260 may be formed from the end surface 230 to the vicinity of the portion of the main surface 210 where the plating film 291 is formed. The side surface 260 may be formed from the end surface 230 to the portion of the main surface 210 where the plating film 291 is formed. The side surface 260 is an example of a third side surface. The intersection line 265 is an example of a fifth intersection line.
[0059] 19(b), the side surface 260 has a concave surface 261 formed on the +Z side in the thickness direction of the metal plate 100, and a concave surface 262 formed on the -Z side. The concave surfaces 261 and 262 are connected, and a pointed protrusion 263 exists at the boundary between them. The protrusion 263 is, for example, on the +Z side of the center in the thickness direction of the metal plate 100. The recess formed in the resist 810 to form the side surface 260 intersects with the cutting line CL.
[0060] When half-etching of the metal plate 100 is performed using such resists 810 and 820 as an etching mask, as shown in Figures 18(a) and 19(a), the frame portion 20, inner leads 200, outer leads 300, die pad 400, connecting portion 500, dam bar 600, and support bar 700 are formed on the metal plate 100. At this time, the side surfaces 240 and 260 are formed so as to intersect with the cutting line CL. Next, the resists 810 and 820 are removed. Figures 18(a) and 19(a) show the state after the resists 810 and 820 have been removed.
[0061] Next, as in the first embodiment, a plating film 291 is formed on the main surface 210 of the inner lead 200, and an adhesive tape 292 is attached (see FIG. 7(b)). Next, as shown in FIG. 18(b), the metal plate 100 is cut along the cutting line CL, and the connecting portion 500 and the tip portion of the inner lead 200 are removed. At this time, as shown in FIG. 18(b) and FIG. 19(b), no burrs are generated on the cut surface or in the vicinity thereof. In FIG. 18, the plating film 291 and the adhesive tape 292 are omitted.
[0062] In this manner, the lead frame 3 can be manufactured.
[0063] The third embodiment can also provide the same effects as the first embodiment. Moreover, in the third embodiment, the side surface 260 is provided between the end surface 230 and the side surface 270, which further reduces the area and processing amount of the part of the metal plate 100 that is sheared during cutting, and further reduces the number of sharp parts, which makes it easier to suppress the generation of burrs during cutting.
[0064] (Fourth embodiment) Next, a fourth embodiment will be described. The fourth embodiment differs from the third embodiment mainly in the range of the side surface 260 in the manufacturing method. Fig. 20 is a top view illustrating the manufacturing method of the lead frame according to the fourth embodiment.
[0065] As described above, in the third embodiment, the recess formed in the resist 810 to form the side surface 240 and the recess formed in the resist 810 to form the side surface 260 intersect with the cutting line CL. In contrast, in the fourth embodiment, the recess formed in the resist 810 to form the side surface 260 is located closer to the die pad 400 than the cutting line CL. For this reason, as shown in FIG. 20(a), the side surface 240 is formed so as to intersect with the cutting line CL, but the side surface 260 is formed closer to the die pad 400 than the cutting line CL.
[0066] Then, similarly to the first embodiment, a plating film 291 is formed and an adhesive tape 292 is attached (see FIG. 7(b)), and thereafter, as shown in FIG. 20(b), the metal plate 100 is cut along the cutting line CL to remove the coupling portion 500 and the tip portion of the inner lead 200. In FIG. 20, the plating film 291 and the adhesive tape 292 are omitted.
[0067] In this manner, the lead frame 4 according to the fourth embodiment can be manufactured.
[0068] The fourth embodiment can also provide the same effects as the first embodiment.
[0069] Fifth embodiment Next, a fifth embodiment will be described. The fifth embodiment differs from the fourth embodiment mainly in the range of the side surface 240 in the manufacturing method. Fig. 21 is a top view illustrating the manufacturing method of the lead frame according to the fifth embodiment.
[0070] As described above, in the fourth embodiment, the recess formed in the resist 810 to form the side surface 240 intersects with the cutting line CL, and the recess formed in the resist 810 to form the side surface 260 is located closer to the die pad 400 than the cutting line CL. In contrast, in the fifth embodiment, not only the recess formed in the resist 810 to form the side surface 260 but also the recess formed in the resist 810 to form the side surface 240 is located closer to the die pad 400 than the cutting line CL. Therefore, as shown in FIG. 21(a), the side surfaces 240 and 260 are formed closer to the die pad 400 than the cutting line CL.
[0071] Then, similarly to the first embodiment, a plating film 291 is formed and an adhesive tape 292 is attached (see FIG. 7(b)), and thereafter, as shown in FIG. 21(b), the metal plate 100 is cut along the cutting line CL to remove the coupling portion 500 and the tip portion of the inner lead 200. In FIG. 21, the plating film 291 and the adhesive tape 292 are omitted.
[0072] In this manner, the lead frame 5 according to the fifth embodiment can be manufactured.
[0073] In the fifth embodiment, compared to the reference example, the amount of processing of the metal plate 100 during cutting is reduced, and the number of sharp edges is also reduced, making it easier to suppress the generation of burrs during cutting. That is, by forming the side surfaces 240 and 260, the etching solution is more likely to spread to the portions where the side surfaces 250 and 270 are formed during wet etching of the metal plate 100, and the convex portions formed on the side surfaces 250 and 270 are smaller. Therefore, the sharp edges are smaller, and the generation of burrs during cutting is suppressed. This effect can also be obtained in the first to fourth embodiments.
[0074] Although the preferred embodiments have been described in detail above, the present disclosure 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]
[0075] 1, 3, 4, 5 Leadframe 2. Semiconductor Devices 40 Semiconductor elements 44 Bonding Wire 50 Bali 100 metal plate 200 Inner Lead 210, 220 Main surface 230 End face 235, 245, 255, 265, 275 intersection line 240, 250, 260, 270 Side 241, 242, 261, 262, 271, 272 concave 243, 263, 273 Convex 300 outer lead 400 Die Pad 500 Connection section 600 Dambar 700 Support Bar 810, 820 Resist 811, 821 Covering pattern 812, 822 Opening 814 Recess L1, L2, L3 Imaginary lines
Claims
1. A plurality of inner leads are arranged in a first direction, The inner lead is A first main surface parallel to the first direction; an end surface connected to the first main surface; a first side surface connected to the first main surface and the end surface; a second side surface connected to the first main surface and the first side surface; having In a plan view perpendicular to the first main surface, an angle between a first virtual line including a first intersection line between the first main surface and the end surface and a second virtual line including a second intersection line between the first main surface and the second side surface is less than 90 degrees on the inner lead side; A lead frame in which a third intersection line between the first main surface and the first side surface is on the inner lead side of the first imaginary line and the second imaginary line.
2. the inner lead has a second main surface opposite to the first main surface, The lead frame according to claim 1 , wherein within a range including the second side surface in the longitudinal direction of the inner lead, the width of the inner lead is wider at the first main surface than at the second main surface.
3. 3. The lead frame according to claim 1, wherein the third intersection line is a curved line recessed toward the inside of the inner lead.
4. The inner lead is a third side surface connected to the first main surface and connected to the end surface on the opposite side to the first side surface; a fourth side surface connected to the first main surface and the third side surface; having In a plan view perpendicular to the first main surface, an angle between the first virtual line and a third virtual line including a fourth intersection line between the first main surface and the fourth side surface is 90 degrees or more on the inner lead side; 3 . The lead frame according to claim 1 , wherein a fifth intersection line between the first main surface and the third side surface is on the inner lead side of the first imaginary line and the third imaginary line.
5. 5. The lead frame according to claim 4, wherein the fifth intersection line is a curved line recessed toward the inside of the inner lead.
6. The lead frame according to claim 1 , further comprising a plating film provided on the first main surface.
7. 3. The lead frame according to claim 1, wherein the end faces of the inner leads are flush with each other among the plurality of inner leads.
8. forming a plurality of inner leads arranged in a first direction and a connecting portion connecting ends of the plurality of inner leads by wet etching a metal plate having a first main surface; removing the connecting portion by cutting the metal plate along a cutting line; having In the wet etching, the inner lead is a first side surface that is continuous with the first main surface and intersects with the cutting line; a second side surface connected to the first main surface and the first side surface; Forming In a plan view perpendicular to the first main surface, an angle between a first virtual line including the cutting line and a second virtual line including a second intersection line between the first main surface and the second side surface is less than 90 degrees on the inner lead side; A method for manufacturing a lead frame, wherein a third intersection line between the first main surface and the first side surface is on the inner lead side of the first virtual line and the second virtual line.
9. In the wet etching, the inner lead is a third side surface that is continuous with the first main surface and intersects with the cutting line on an opposite side to the first side surface; a fourth side surface connected to the first main surface and the third side surface; Forming In a plan view perpendicular to the first main surface, an angle between the first virtual line and a third virtual line including a fourth intersection line between the first main surface and the fourth side surface is 90 degrees or more on the inner lead side; The method for manufacturing a lead frame according to claim 8 , wherein a fifth intersection line between the first main surface and the third side surface is on the inner lead side of the first imaginary line and the third imaginary line.
10. A die pad; A semiconductor element mounted on the die pad; a plurality of inner leads provided around the die pad and aligned in a first direction; a wire connecting the semiconductor element and the inner lead; having The inner lead is A first main surface parallel to the first direction; an end surface connected to the first main surface; a first side surface connected to the first main surface and the end surface; a second side surface connected to the first main surface and the first side surface; having In a plan view perpendicular to the first main surface, an angle between a first virtual line including a first intersection line between the first main surface and the end surface and a second virtual line including a second intersection line between the first main surface and the second side surface is less than 90 degrees on the inner lead side; A semiconductor device in which a third intersection line between the first main surface and the first side surface is on the inner lead side of the first imaginary line and the second imaginary line.