Lead frame and method of manufacturing the same

Abstract

To provide a lead frame capable of improving adhesion between a metal part and a resin part, and to provide a method of manufacturing the same.SOLUTION: The lead frame 10 includes a lead portion 12 and a resin portion 18 disposed around the lead portion 12. The lead part 12 has an inner lead 51 in which an inner lead tip surface 51c is formed at the tip, and an outer terminal 53 having an outer terminal surface 17. The inner lead 51 is thinned from the back surface side, and at least a part of the inner lead tip surface 51c is in close contact with the plastic part 18. The front-surface-side end 51c of the inner lead tip surface 51d is located inside the back-surface-side end 51c of the inner lead tip surface 51e.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a lead frame and a method for manufacturing the same. [Background technology]

[0002] In recent years, there has been a demand for smaller and thinner semiconductor devices mounted on substrates. To meet this demand, various so-called QFN (Quad Flat Non-lead) type semiconductor devices have been proposed, which use a lead frame, a semiconductor element mounted on the mounting surface of the lead frame is sealed with sealing resin, and a portion of the leads is exposed on the back surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,460,986 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, lead frames in which a metal portion and a resin portion are integrated have been known (for example, Patent Document 1). In such lead frames in which a metal portion and a resin portion are integrated, it is desired to improve the adhesion between the metal portion and the resin portion.

[0005] The present disclosure provides a lead frame and a manufacturing method thereof that can improve adhesion between a metal portion and a resin portion. [Means for solving the problem]

[0006] The embodiments of the present disclosure relate to the following [1] to

[13] .

[0007] [1] A lead frame comprising a lead portion and a resin portion around the lead portion and arranged on the back surface side of the lead frame, the lead portion having an inner lead with an inner lead tip surface formed at its tip and an external terminal with an external terminal surface, the inner lead being thinned from the back surface side, at least a portion of the inner lead tip surface being in close contact with the resin portion, and the front surface side end of the inner lead tip surface being located more inward than the back surface side end of the inner lead tip surface.

[0008] [2] The lead frame according to [1], wherein in a cross section along the longitudinal direction of the inner lead, the tip surface of the inner lead is linearly inclined from the front surface end toward the back surface end.

[0009] [3] The lead frame according to [1], wherein in a cross section along the longitudinal direction of the inner lead, the tip surface of the inner lead curves outward from the front surface end toward the back surface end.

[0010] [4] A lead frame described in any one of [1] to [3], wherein the surface of the resin portion is located on the back side of the surface of the inner lead, inside the tip surface of the inner lead.

[0011] [5] A lead frame described in any one of [1] to [4], further comprising a die pad, wherein the surface of the resin portion is located on the back side of the surface of the die pad between the die pad and the tip surface of the inner lead.

[0012] [6] A lead frame according to any one of [1] to [3], wherein the surface of the resin portion is located closer to the surface of the inner lead than the surface of the inner lead, inside the tip end surface of the inner lead.

[0013] [7] The lead frame according to [6], wherein the back surface of the resin portion is located on the same plane as the external terminal surface inside the tip surface of the inner lead.

[0014] [8] A lead frame according to any one of [1] to [7], wherein the roughness of the portion of the inner lead that is in close contact with the resin portion is greater than the roughness of the surface of the inner lead.

[0015] [9] A lead frame according to any one of [1] to [7], wherein the roughness of the portion of the inner lead that is in close contact with the resin portion is the same as the roughness of the surface of the inner lead.

[0016]

[10] A lead frame described in any one of [1] to [9], wherein at the boundary between the inner lead and the resin portion, the corner between the surface of the inner lead and the tip surface of the inner lead is curved in a cross-sectional view.

[0017]

[11] The lead frame according to any one of [1] to

[10] , wherein a boundary recess is formed at the boundary between the inner lead and the resin portion.

[0018]

[12] A lead frame described in any one of [1] to

[11] , wherein the lead portion has a connection portion located outside the external terminal, a recess is formed on the back surface of the connection portion, and the resin portion is not filled in the recess.

[0019]

[13] A method for manufacturing a lead frame, comprising the steps of: preparing a metal substrate; forming a back-side recess on the back side of the metal substrate; forming a resin portion on the metal substrate and covering the back-side recess with the resin portion; removing the resin portion from the back side by a predetermined thickness; and forming a lead portion by thinning the metal substrate from the front side, wherein the lead portion has an inner lead having an inner lead tip surface formed at its tip, and an external terminal having an external terminal surface, the inner lead being thinned from the back side, at least a portion of the inner lead tip surface being in close contact with the resin portion, and the front side end of the inner lead tip surface being located more inward than the back side end of the inner lead tip surface. [Effects of the Invention]

[0020] According to the present disclosure, it is possible to improve the adhesion between the metal part and the resin part. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a plan view showing a lead frame according to a first embodiment. [Figure 2] FIG. 2 is a bottom view showing the lead frame according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the lead frame according to the first embodiment (a cross-sectional view taken along line III-III in FIG. 1). [Figure 4] FIG. 4 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of the inner lead. [Figure 5] FIG. 5 is a plan view showing the semiconductor device according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view (cross-sectional view taken along line VI-VI in FIG. 5) showing the semiconductor device according to the first embodiment. [Figure 7] 7(A) to 7(G) are cross-sectional views showing a method for manufacturing a lead frame according to the first embodiment. [Figure 8] 8(A) to 8(E) are cross-sectional views showing a method for manufacturing a semiconductor device according to the first embodiment. [Figure 9] 7(A) to 7(G) are cross-sectional views showing a method for manufacturing a lead frame according to a modified example of the first embodiment. [Figure 10] FIG. 10 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a first modified example. [Figure 11] FIG. 11 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a second modified example. [Figure 12] FIG. 12 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a third modified example. [Figure 13] FIG. 13 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a fourth modified example. [Figure 14]FIG. 14 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a fifth modified example. [Figure 15] FIG. 15 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to another example of the fifth modified example. [Figure 16] FIG. 16 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a sixth modified example. [Figure 17] FIG. 17 is a partially enlarged cross-sectional view showing the periphery of the tip end surface of an inner lead according to a seventh modified example. [Figure 18] FIG. 18 is a cross-sectional view showing a lead frame according to a second embodiment. [Figure 19] FIG. 19 is a cross-sectional view showing a state in which the semiconductor device according to the second embodiment is mounted on a wiring board. [Figure 20] 20(A) to 20(G) are cross-sectional views showing a method for manufacturing a lead frame according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) The first embodiment will be described below with reference to Figures 1 to 17. In the following figures, the same parts are denoted by the same reference numerals, and some detailed descriptions may be omitted.

[0023] In this specification, the X direction and the Y direction refer to two directions parallel to each side of the lead frame 10. The X direction and the Y direction are perpendicular to each other. The Z direction is perpendicular to both the X direction and the Y direction. The terms "inner" and "inside" refer to the side facing the center of each package area 10a. The terms "outer" and "outside" refer to the side away from the center of each package area 10a. The term "front surface" refers to the surface on which the semiconductor element 21 is mounted (the positive side in the Z direction). The term "back surface" refers to the surface opposite the "front surface" (the negative side in the Z direction) and connected to an external wiring board (not shown).

[0024] In this specification, half-etching refers to etching a material to be etched partway in its thickness direction. The thickness of the material to be etched after half-etching is, for example, 30% to 75%, preferably 40% to 60%, of the thickness of the material to be etched before half-etching.

[0025] (Lead frame configuration) First, an outline of the lead frame according to the present embodiment will be described with reference to Figures 1 to 4. Figures 1 to 4 are diagrams showing the lead frame according to the present embodiment.

[0026] As shown in Figures 1 and 2, the lead frame 10 includes a plurality of package areas (unit lead frame) 10a. The package areas 10a are arranged in a plurality of rows and columns (in a matrix). This is not a limitation, and it is sufficient that there is one or more package areas 10a. Each package area 10a corresponds to a semiconductor device 20 (described later), and is an area located inside the imaginary lines in Figures 1 and 2. The imaginary lines in Figures 1 and 2 correspond to the outer periphery of the semiconductor device 20.

[0027] Next, the configuration of the lead frame 10 will be further described with reference to FIGS.

[0028] As shown in FIGS. 1 to 3, the lead frame 10 includes a die pad 11, a plurality of elongated lead portions 12, and a resin portion 18. The lead portions 12 are arranged around the die pad 11. Each lead portion 12 electrically connects a semiconductor element 21 to a wiring board (not shown). The resin portion 18 is arranged around the die pad 11 and the lead portions 12. Support leads (support members) 13 are arranged between adjacent package regions 10a. The support leads 13 support the die pad 11 and the lead portions 12. The plurality of support leads 13 extend along the X and Y directions, respectively.

[0029] The die pad 11 has a substantially square planar shape. The die pad 11 is not half-etched and has the same thickness as the metal substrate (metal substrate 31 described below) before processing. The planar shape of the die pad 11 is not limited to a square, and may be a polygon such as a rectangle. The front or back side of the die pad 11 may be partially thinned by, for example, half-etching. This allows the resin of the resin portion 18 to fill the thinned portion, increasing the contact area between the metal portion of the die pad 11 and the resin portion 18, thereby improving the adhesion between the metal portion of the die pad 11 and the resin portion 18.

[0030] A suspension lead 14 is connected to each of the four corners of the die pad 11. The die pad 11 is connected and supported by the support leads 13 via the four suspension leads 14. Each support lead 13 is arranged around the package area 10a and outside the package area 10a. Each support lead 13 has a long, thin rod shape. A plurality of lead portions 12 are connected to the support lead 13 at intervals along the longitudinal direction of the support lead 13. The support leads 13 are not thinned, but the support leads 13 may be thinned from the back surface side.

[0031] A support lead connecting portion 14a is located in the area surrounded by the four package areas 10a. Four suspension leads 14 extending from the four package areas 10a are connected to each other at the support lead connecting portion 14a. Four support leads 13 are connected to each support lead connecting portion 14a.

[0032] A peripheral region 10b is located around each package region 10a. The peripheral region 10b is a region located outside each package region 10a and formed adjacent to each package region 10a. The peripheral region 10b is located between two adjacent package regions 10a. In other words, the two adjacent package regions 10a are connected to each other via the peripheral region 10b. The support leads 13 are located within the peripheral region 10b.

[0033] As shown in FIG. 3, the die pad 11 has a die pad front surface 11a and a die pad back surface 11b. The die pad front surface 11a is located on the front surface side. The die pad back surface 11b is located on the back surface side. A semiconductor element 21, which will be described later, is mounted on the die pad front surface 11a. The die pad back surface 11b is exposed to the outside from the lead frame 10. In addition, a die pad side surface 11c is formed on the side of the die pad 11 facing the lead portion 12. The die pad side surface 11c is in close contact with the resin portion 18.

[0034] As will be described later, each lead portion 12 is connected to a semiconductor element 21 via a bonding wire 22. Each lead portion 12 is arranged between itself and the die pad 11 via a resin portion 18. The lead portion 12 of one package area 10a and the lead portion 12 of the package area 10a adjacent to that package area 10a are connected to each other by a lead connecting portion 16. The lead connecting portion 16 is located outside each package area 10a.

[0035] The lead portions 12 are arranged at intervals from one another around the periphery of the die pad 11 along the longitudinal direction of the support leads 13. An external terminal surface 17 is formed on the back surface of each lead portion 12, and is electrically connected to an external wiring board (not shown). Each external terminal surface 17 is exposed to the outside from the semiconductor device 20 after the semiconductor device 20 (described later) is manufactured.

[0036] 3, the lead portion 12 has an inner lead 51 and an external terminal 53. The inner lead 51 is located on the inner side (the die pad 11 side). The external terminal 53 is located on the outer side (the support lead 13 side) of the inner lead 51. The inner lead 51 extends from the external terminal 53 toward the die pad 11, and an internal terminal 15 is formed at the tip of the inner lead 51 on the front surface side. The internal terminal 15 is an area that is electrically connected to the semiconductor element 21 via a bonding wire 22, as will be described later.

[0037] The inner lead 51 is thinned from the back surface side by, for example, half etching. The inner lead 51 has an inner lead front surface 51a and an inner lead back surface 51b. The above-mentioned internal terminal 15 is formed on a part of the inner lead front surface 51a. The inner lead back surface 51b is in close contact with the resin part 18. An inner lead front end surface 51c is formed at the front end of the inner lead 51. The inner lead front end surface 51c is located on the side of the inner lead 51 facing the die pad 11. The entire inner lead front end surface 51c is in close contact with the resin part 18.

[0038] As shown in FIG. 4, the inner lead tip surface 51c has a front surface end 51d and a back surface end 51e. The front surface end 51d is located closest to the front surface of the inner lead tip surface 51c. The front surface end 51d may also be referred to as the upper end. The inner side of the front surface end 51d (the side closest to the die pad 11, opposite the external terminals 53) is in close contact with the resin part 18. The front surface side (positive side in the Z direction) of the front surface end 51d is exposed to the outside of the lead frame 10. The front surface side (positive side in the Z direction) of the front surface end 51d may be covered with the plating layer 25. The back surface end 51e is located closest to the back surface of the inner lead tip surface 51c. The back surface end 51e may also be referred to as the lower end. The inner side of the back surface end 51e (the side closest to the die pad 11, opposite the external terminals 53) is in close contact with the resin part 18. The back surface side (negative side in the Z direction) of the back surface end 51e is in close contact with the resin part 18. The inner lead back surface 51b extends from the back surface end 51e toward the outside (the external terminal 53 side, the opposite side to the die pad 11).

[0039] The front surface side end 51d of the inner lead tip surface 51c is located more inward than the back surface side end 51e (toward the die pad 11, opposite the external terminals 53). In other words, the front surface side end 51d is located farther from the external terminals 53 and the support leads 13 than the back surface side end 51e. The inner lead tip surface 51c gradually slopes outward (toward the external terminals 53, opposite the die pad 11) from the front surface side end 51d toward the back surface side end 51e. In this case, the distance between the inner lead tip surface 51c and the die pad side surface 11c gradually narrows from the back surface side end 51e toward the front surface side end 51d.

[0040] In a cross section along the longitudinal direction of the inner lead 51, the inner lead tip surface 51c is linearly inclined from the front surface end 51d to the back surface end 51e. The angle θ1 formed between the inner lead tip surface 51c and the inner lead surface 51a may be 50° to 85°, or 60° to 75°.

[0041] The thickness T3 of the inner lead 51 at the rear surface side end 51e may be 30% to 60% or 40% to 50% of the maximum thickness T1 of the lead frame 10 described later. The thickness T3 of the inner lead 51 may be 24 μm to 180 μm or 32 μm to 150 μm.

[0042] In a cross section along the longitudinal direction of the inner lead 51, the distance L1 between the front surface end 51d and the back surface end 51e may be 1 μm or more and 150 μm or less, or 20 μm or more and 90 μm or less.

[0043] In a cross section along the longitudinal direction of the inner lead 51, the distance L2 between the surface side end 51d and the die pad side surface 11c may be 50 μm or more and 150 μm or less, or may be 30 μm or more and 75 μm or less.

[0044] A plating layer 25 is provided on the inner lead surface 51a to improve adhesion with the bonding wire 22. The plating layer 25 may be made of, for example, silver plating. The plating layer 25 is also formed on the die pad surface 11a of the die pad 11. The plating layer 25 can be formed partially on the inner lead surface 51a or the die pad surface 11a, but the plating layer 25 may also be formed up to the end of the inner lead surface 51a or the end of the die pad surface 11a.

[0045] 3, an external terminal surface 53a is formed on the surface of the external terminal 53. The above-mentioned external terminal surface 17 is formed on the back surface of the external terminal 53. The portion of the external terminal 53 where the external terminal surface 17 is formed is not half-etched and has the same thickness as the die pad 11.

[0046] In this embodiment, the lead connecting portion 16 is thinned from the back surface side. A recess 19 is formed on the back surface of the lead connecting portion 16. A resin portion 18 is filled in the recess 19.

[0047] As shown in FIGS. 1 and 2, the resin portion 18 is continuously formed so as to straddle one package region 10a, a surrounding region 10b around the package region 10a, and an adjacent package region 10a.

[0048] In each package area 10a, the resin portion 18 is disposed around the die pad 11 and the leads 12. That is, as shown in FIG. 1, when viewed from the front side, the resin portion 18 is located in an area surrounded by one side of the die pad 11, the plurality of leads 12 facing that side, two suspension leads 14, and the outer periphery of the package area 10a. As shown in FIG. 2, when viewed from the back side, the resin portion 18 is located in an area surrounded by each side of the die pad 11, the plurality of external terminal surfaces 17, the two suspension leads 14, and the outer periphery of the package area 10a. Note that in FIGS. 1 and 2, the resin portion 18 is indicated by hatching (the same applies to FIG. 5, which will be described later).

[0049] As shown in FIG. 3 , the resin portion 18 is disposed so as to contact the external terminals 53, the inner lead back surface 51b, the inner lead tip surface 51c, and the die pad side surface 11c. The resin portion 18 has a resin front surface 18a located on the front side and a resin back surface 18b located on the back side. Of these, the resin front surface 18a is exposed outward from the front side of the lead frame 10. The resin front surface 18a, the die pad front surface 11a, the inner lead surface 51a, and the external terminal surface 53a are all located on the same plane. The resin back surface 18b is exposed outward from the back side of the lead frame 10. The resin back surface 18b, the die pad back surface 11b, and the external terminal surface 17 are all located on the same plane. The resin portion 18 has a resin side surface 18c between the resin front surface 18a and the resin back surface 18b. The resin side surface 18c is in close contact with the die pad 11 or the lead portion 12.

[0050] A thermosetting resin such as a silicone resin or an epoxy resin, or a thermoplastic resin such as a PPS resin can be used as the resin portion 18. Note that, in order to improve adhesion between the resin portion 18 and a sealing resin 23 described below, it is preferable to use the same material for the resin portion 18 as for the sealing resin 23.

[0051] As shown in FIG. 3 , the thickness T2 of the resin portion 18 refers to the distance between the resin front surface 18a and the resin back surface 18b of the resin portion 18. The thickness T2 of the resin portion 18 may be the same as the maximum thickness T1 of the lead frame 10. The thickness T4 of the resin portion 18 on the back surface side of the inner lead 51 may be 30% to 60%, or 40% to 50%, of the maximum thickness T1 of the lead frame 10. The thickness T4 of the resin portion 18 on the back surface side of the inner lead 51 may be 24 μm to 180 μm, or 32 μm to 150 μm. The thickness T4 of the resin portion 18 on the back surface side of the inner lead 51 refers to the thickness of the thickest portion of the resin portion 18 in contact with the inner lead back surface 51b. The thickness T4 may also be the thickness of the resin portion 18 in contact with the back surface end 51e.

[0052] As will be described later, the resin portion 18 is polished from the back surface side (FIG. 7(E)). When polishing of the resin portion 18 is completed, the back surface of the metal substrate 31 is also slightly polished. Therefore, the roughness of the back surface of the lead frame 10 may be rougher than the roughness of the front surface of the lead frame 10. For example, the average roughness Ra of the back surface of the lead frame 10 may be greater than 0.1 μm and less than or equal to 0.35 μm. When the average roughness Ra of the back surface of the lead frame 10 exceeds 0.1 μm, the adhesion between the back surface of the lead frame 10 and the solder plating can be improved. When the average roughness Ra of the back surface of the lead frame 10 is less than or equal to 0.35 μm, the generation of metal chips (burrs) on the back surface of the lead frame 10 can be suppressed. The average roughness Ra of the front surface of the lead frame 10 may be greater than or equal to 0.01 μm and less than or equal to 0.15 μm. In this specification, the average roughness Ra refers to the arithmetic mean roughness defined in JIS B0601:2013.

[0053] The lead frame 10 described above is generally made of metal such as copper, copper alloy, 42 alloy (Ni42% Fe alloy), etc. The maximum thickness T1 of the lead frame 10 depends on the configuration of the semiconductor device 20 to be manufactured, but may be 35 μm or more and 300 μm or less, or 80 μm or more and 200 μm or less.

[0054] (Configuration of semiconductor device) Next, the semiconductor device according to this embodiment will be described with reference to Figures 5 and 6. Figures 5 and 6 are diagrams showing the semiconductor device (QFN type) according to this embodiment.

[0055] 5 and 6, a semiconductor device (semiconductor package) 20 includes a die pad 11, a plurality of leads 12, a resin portion 18, a semiconductor element 21, a plurality of bonding wires (connecting members) 22, and a sealing resin 23. The plurality of leads 12 are arranged around the die pad 11. The semiconductor element 21 is mounted on the die pad 11. The bonding wires 22 electrically connect the leads 12 and the semiconductor element 21 to each other. The resin portion 18 is arranged around the die pad 11 and the leads 12. The sealing resin 23 resin-seals the die pad 11, the leads 12, the semiconductor element 21, and the bonding wires 22.

[0056] Of these, the die pad 11, lead portion 12, and resin portion 18 are made from the lead frame 10 described above. Each lead portion 12 has an inner lead 51 and an external terminal 53. An inner lead tip surface 51c is formed at the tip of the inner lead 51. The inner lead tip surface 51c is in close contact with the resin portion 18. A front surface side end 51d of the inner lead tip surface 51c is located more inward than a back surface side end 51e of the inner lead tip surface 51c.

[0057] In addition, the configurations of the die pad 11, lead portion 12, and resin portion 18 are the same as those shown in Figures 1 to 4 above, except for the areas not included in the semiconductor device 20, so detailed explanations will be omitted here.

[0058] Various types of semiconductor elements that are commonly used in the past can be used as the semiconductor element 21. The semiconductor element 21 is not particularly limited, but may be, for example, an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode, etc. The semiconductor element 21 has a plurality of electrodes 21a to which bonding wires 22 are each attached. The semiconductor element 21 is fixed to a plating layer 25 located on the surface of the die pad 11 by an adhesive 24 such as die bonding paste.

[0059] Each bonding wire 22 is made of a highly conductive material such as gold or copper. One end of each bonding wire 22 is connected to an electrode 21a of the semiconductor element 21. The other end of each bonding wire 22 is connected to a plating layer 25 located on the internal terminal 15 of each lead portion 12.

[0060] The sealing resin 23 may be a thermosetting resin such as a silicone resin or an epoxy resin, or a thermoplastic resin such as a PPS resin. The overall thickness of the sealing resin 23 may be approximately 300 μm or more and 1500 μm or less. Furthermore, one side of the sealing resin 23 (one side of the semiconductor device 20) may be, for example, 1 mm or more and 16 mm or less. In the space between the die pad 11 and the lead portion 12, the sealing resin 23 is in close contact with the resin surface 18a of the resin portion 18. Note that the sealing resin 23 is not shown in FIG. 5.

[0061] (Lead frame manufacturing method) Next, a method for manufacturing the lead frame 10 shown in FIGS. 1 to 4 will be described with reference to FIGS. 7(A) to 7(G).

[0062] 7(A), a flat metal substrate 31 is prepared. A substrate made of a metal such as copper, a copper alloy, or a 42 alloy (a 42% Ni / Fe alloy) can be used as the metal substrate 31. It is preferable to use a metal substrate 31 that has been subjected to degreasing and cleaning on both sides.

[0063] Next, a photosensitive resist is applied to the entire front and back surfaces of the metal substrate 31 and dried. Subsequently, the photosensitive resist on the metal substrate 31 is exposed to light through a photomask and developed. This forms an etching resist layer 32 on the front surface of the metal substrate 31. Similarly, an etching resist layer 33 having desired openings 33b is formed on the back surface of the metal substrate 31 (FIG. 7(B)). The etching resist layer 32 does not have openings, but it may have openings.

[0064] Next, the metal substrate 31 is thinned partway in the thickness direction from the back side of the metal substrate 31 by half etching (FIG. 7(C)). In this case, the back side of the metal substrate 31 is etched with an etchant, using the back side etching resist layer 33 as a corrosion-resistant film. As a result, back side recesses 36, 37, which are non-penetrating recesses, are formed on the back side of the metal substrate 31. The etchant can be selected appropriately depending on the material of the metal substrate 31 used. For example, when copper is used as the metal substrate 31, an aqueous ferric chloride solution may be used as the etchant. This aqueous ferric chloride solution may be spray-etched from one or both sides of the metal substrate 31.

[0065] The rear surface recesses 36, 37 have a shape corresponding to the resin portion 18. The rear surface recess 36 has a first recess region 36a and a second recess region 36b. The first recess region 36a corresponds to the space between the die pad side surface 11c and the inner lead tip surface 51c. The second recess region 36b corresponds to the rear surface side of the inner lead 51. The depth of the first recess region 36a is deeper than the depth of the second recess region 36b. By providing the opening 33b and the halftone dot portion (halftone portion) 33c in the etching resist layer 33 on the rear surface side of the inner lead 51, the first recess region 36a and the second recess region 36b, which have different depths, can be formed. The halftone dot portion 33c is provided at a position corresponding to the second recess region 36b. The first recess region 36a is formed only by etching from the rear surface side. As a result, the portion corresponding to the inner lead tip surface 51c is inclined, and the portion corresponding to the front surface end 51d is positioned more inward than the portion corresponding to the rear surface end 51e. The rear surface side recess 37 has a shape corresponding to the recess 19 .

[0066] Next, the etching resist layer 33 on the back surface side is peeled off and removed, leaving the etching resist layer 32 on the front surface side. Next, the metal substrate 31 is washed with water and dried. Next, a resin portion 18 is formed on the back surface side of the metal substrate 31 (FIG. 7(D)). The resin portion 18 is filled into the back surface recesses 36, 37. The resin portion 18 is also formed on the back surface of the metal substrate 31 in portions corresponding to the die pad back surface 11b and the external terminal surface 17. The resin portion 18 may cover the entire back surface of the metal substrate 31. In this case, the resin portion 18 may be formed on the back surface side of the metal substrate 31 by, for example, inkjet printing or screen printing using a thermosetting resin or a thermoplastic resin.

[0067] Next, the etching resist layer 32 on the front surface side is removed. Next, a predetermined thickness of the resin portion 18 is removed to expose the back surface of the metal substrate 31 (FIG. 7(E)). Specifically, the resin portion 18 is polished from the back surface side, and polishing of the resin portion 18 is completed when the back surface of the metal substrate 31 is revealed. At this time, the metal surfaces constituting the die pad back surface 11b and the external terminal surface 17 are exposed on the back surface side. Note that the resin portion 18 may be polished using, for example, a method similar to back grinding (also called back grinding) used to finish the semiconductor element 21 to a predetermined thickness.

[0068] Next, a photosensitive resist is applied to the entire rear surface of the metal substrate 31 and dried. This forms an etching resist layer 35 (FIG. 7(F)). The etching resist layer 35 on the rear surface side may cover the entire rear surface of the metal substrate 31. Note that, for example, a dry film resist may be used as the etching resist layer 35.

[0069] Next, half etching is performed to thin the entire surface of the metal substrate 31 from the front surface side to partway in the thickness direction (FIG. 7(F)). This forms the outlines of the die pad 11 and the lead portions 12. By half etching the front surface side of the metal substrate 31, the resin portion 18 located between the die pad 11 and the lead portions 12 is exposed on the front surface side. In addition, the die pad surface 11a of the die pad 11, and the inner lead surface 51a and external terminal surface 53a of the lead portions 12 are formed. The etchant may be the same as that used when etching the back surface side of the metal substrate 31 (FIG. 7(C)).

[0070] 7(F) may be a step of polishing the surface of the metal substrate 31. Alternatively, the step of thinning the surface of the metal substrate 31 may be a step of polishing the surface of the metal substrate 31 and then half-etching the surface of the metal substrate 31. Polishing the surface of the metal substrate 31 may be performed simultaneously with polishing the resin part 18 (FIG. 7(E)), or may be performed at a different timing from polishing the resin part 18 (FIG. 7(E)).

[0071] Next, the etching resist layer 35 is peeled off and then the metal substrate 31 is washed with water and dried. Thereafter, the die pad 11 and the lead portions 12 are each subjected to electrolytic plating. This causes a metal (e.g., silver) to deposit at predetermined positions on the die pad 11 and the lead portions 12, forming plating layers 25. In this manner, the lead frame 10 shown in FIGS. 1 to 4 is obtained (FIG. 7(G)).

[0072] (Method of manufacturing a semiconductor device) Next, a method for manufacturing the semiconductor device 20 shown in FIGS. 5 and 6 will be described with reference to FIGS. 8(A) to 8(E).

[0073] First, a lead frame 10 is fabricated (FIG. 8(A)) by, for example, the method shown in FIGS. 7(A)-(G).

[0074] 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 on and fixed to the die pad 11 using an adhesive 24 such as die bonding paste (die attach process) (FIG. 8(B)).

[0075] Next, each electrode 21a of the semiconductor element 21 and the plating layer 25 on the internal terminal 15 formed on each lead portion 12 are electrically connected to each other by a bonding wire (connecting member) 22 (wire bonding process) (Figure 8(C)).

[0076] Next, a sealing resin 23 is formed on the lead frame 10 by injection molding or transfer molding, for example, a thermosetting resin or a thermoplastic resin (FIG. 8(D)). In this way, the lead frame 10, the lead portions 12, the semiconductor element 21, and the bonding wires 22 are sealed.

[0077] Next, the lead frame 10 is separated into each semiconductor device 20 by dicing the sealing resin 23 and the lead connecting portions 16 located between the semiconductor elements 21 (FIG. 8(E)). At this time, the sealing resin 23 and the lead connecting portions 16 (support leads 13) located in the peripheral region 10b may be cut while rotating a blade made of, for example, a diamond grindstone.

[0078] In this way, the semiconductor device 20 shown in FIGS. 5 and 6 is obtained (FIG. 8(E)).

[0079] As described above, according to this embodiment, the inner lead 51 is thinned from the back surface side, and the inner lead tip surface 51c is in close contact with the resin portion 18. The front surface side end 51d of the inner lead tip surface 51c is located more inward than the back surface side end 51e. This improves the adhesion between the inner lead tip surface 51c and the resin portion 18. In particular, even when the thickness T3 (FIG. 4) of the inner lead 51 is thinned, the area of ​​the inner lead tip surface 51c can be secured, and the inner lead tip surface 51c and the resin portion 18 can be in close contact with each other over a wide area. As a result, peeling of the inner lead tip surface 51c from the resin portion 18 can be suppressed.

[0080] Furthermore, according to this embodiment, the inner lead tip surface 51c is linearly inclined from the front surface end 51d to the back surface end 51e, which makes it possible to suppress dimensional variations of the inner lead tip surface 51c when the shape of the inner lead tip surface 51c is formed by etching.

[0081] (Modification of the lead frame manufacturing method) Next, a modified example of the method for manufacturing the lead frame 10 shown in FIGS. 1 to 4 will be described with reference to FIGS. 9(A)-(G). FIGS. 9(A)-(G) are cross-sectional views showing a modified method for manufacturing the lead frame 10 according to the present embodiment. The modified example shown in FIGS. 9(A)-(G) mainly differs in the order of the step of thinning the surface of the metal substrate 31 partway in the thickness direction (FIG. 9(E)) and the step of polishing the resin portion 18 to a predetermined thickness (FIG. 9(F)). The other configurations are substantially the same as the method for manufacturing the lead frame 10 shown in FIGS. 7(A)-(G). In FIGS. 9(A)-(G), the same parts as those in FIGS. 7(A)-(G) are designated by the same reference numerals, and detailed description thereof will be omitted.

[0082] First, a flat metal substrate 31 is prepared in substantially the same manner as in the step shown in FIG. 7(A) (FIG. 9(A)).

[0083] Next, etching resist layers 32 and 33 are formed on the metal substrate 31 in substantially the same manner as in the step shown in FIG. 7(B) (FIG. 9(B)).

[0084] Next, the metal substrate 31 is etched (FIG. 9C) in substantially the same manner as the step shown in FIG. 7C. As a result, the metal substrate 31 is thinned from the rear surface side thereof to the middle of the thickness direction, and rear surface side recesses 36 and 37 are formed.

[0085] Next, in substantially the same manner as the step shown in FIG. 7(D), the resin portion 18 is formed on the back surface side of the metal substrate 31 (FIG. 9(D)).

[0086] Next, the etching resist layer 32 on the front surface side is removed in substantially the same manner as the step shown in Fig. 7(E). Next, the entire surface of the metal substrate 31 is thinned from the front surface side to the middle of the thickness direction by half etching (Fig. 9(E)). This forms the outlines of the die pad 11 and the lead portions 12. By half etching the front surface side of the metal substrate 31, the resin portion 18 located between the die pad 11 and the lead portions 12 is exposed on the front surface side. In addition, the die pad surface 11a of the die pad 11, and the inner lead surface 51a and external terminal surface 53a of the lead portions 12 are formed.

[0087] 7(E), the resin portion 18 is polished to a predetermined thickness to expose the back surface of the metal substrate 31 (FIG. 9(F)). Specifically, the resin portion 18 is polished from the back surface side, and polishing of the resin portion 18 is completed when the back surface of the metal substrate 31 is exposed. At this time, the metal surfaces constituting the die pad back surface 11b and the external terminal surface 17 are exposed on the back surface side.

[0088] 9(E) may be a step of polishing the surface of the metal substrate 31. Alternatively, the step of thinning the surface of the metal substrate 31 may be a step of polishing the surface of the metal substrate 31 after half-etching the surface of the metal substrate 31. Polishing the surface of the metal substrate 31 may be performed simultaneously with polishing the resin portion 18 (FIG. 9(F)), or may be performed at a different timing from polishing the resin portion 18 (FIG. 9(F)). In this case, the positions of the resin portion 18 and the metal portion exposed on the surface can be adjusted as needed.

[0089] 7(G), plating layers 25 are formed at predetermined positions on the die pad 11 and the lead portions 12. In this manner, the lead frame 10 shown in FIGS. 1 to 4 is obtained (FIG. 9(G)).

[0090] 9(A)-(G), when the metal substrate 31 is thinned from the front surface side (FIG. 9(E)), the resin part 18 is formed on the rear surface of the metal substrate 31, so the total thickness of the metal substrate 31 and the resin part 18 is thicker than the thickness of the metal substrate 31 alone. This suppresses deformation when the metal substrate 31 is thinned from the front surface side, making the metal substrate 31 easier to handle.

[0091] (Modification of lead frame) Next, modified examples of the lead frame according to this embodiment will be described with reference to Figures 10 to 17. In Figures 10 to 17, the same parts as in Figures 1 to 9 are designated by the same reference numerals and detailed description thereof will be omitted.

[0092] (First Modification) 10 is a partially enlarged cross-sectional view showing a lead frame 10 according to a first modified example. In the lead frame 10 shown in FIG. 10, the entire inner lead tip surface 51c is in close contact with the resin portion 18. The front surface side end 51d of the inner lead tip surface 51c is located more inward (toward the die pad 11, opposite the external terminals 53) than the back surface side end 51e. The inner lead tip surface 51c gradually slopes outward (toward the external terminals 53, opposite the die pad 11) from the front surface side end 51d toward the back surface side end 51e.

[0093] In this case, in a cross section along the longitudinal direction of the inner lead 51, the inner lead tip surface 51c is inclined in a curved shape from the front surface end 51d to the back surface end 51e. The inner lead tip surface 51c is curved outward (toward the external terminal 53, opposite the die pad 11). The angle θ2 formed between the inner lead tip surface 51c and the inner lead surface 51a may be 5° or more and 60° or less, or may be 15° or more and 45° or less.

[0094] When manufacturing the lead frame 10 shown in Figure 10, when etching the metal substrate 31 from the back side (Figure 7(C)), the inner lead tip surface 51c can be curved outward by appropriately adjusting the etching conditions.

[0095] According to this modification, the inner lead tip surface 51c is curved outward, which makes it possible to increase the area of ​​the inner lead tip surface 51c. Also, the resin portion 18 can be made to bite into the curved inner lead tip surface 51c. As a result, the inner lead tip surface 51c and the resin portion 18 are brought into close contact over a large area, which makes it possible to prevent the inner lead tip surface 51c from peeling off from the resin portion 18.

[0096] (Second Modification) FIG. 11 is a partially enlarged cross-sectional view showing a lead frame 10 according to a second modification. In the lead frame 10 shown in FIG. 11, only a portion of the inner lead tip surface 51c is in close contact with the resin portion 18. The front surface side end 51d of the inner lead tip surface 51c is not in close contact with the resin portion 18. The back surface side end 51e of the inner lead tip surface 51c is in close contact with the resin portion 18. Inside the inner lead tip surface 51c (the die pad 11 side, opposite the external terminal 53), the resin surface 18a is located closer to the back surface (the resin back surface 18b side) than the inner lead surface 51a and the die pad surface 11a. The distance L3 between the inner lead surface 51a and the resin surface 18a may be greater than 0 μm and less than 15 μm, or may be greater than 2 μm and less than 10 μm. The distance between the die pad surface 11a and the resin surface 18a may also be equal to the distance L3. Further, inside the inner lead tip surface 51c (the die pad 11 side, opposite the external terminal 53), the resin back surface 18b is located on the same plane as the external terminal surface 17 and the die pad back surface 11b.

[0097] When manufacturing the lead frame 10 shown in Figure 11, when etching the metal substrate 31 from the front side (Figure 7(F)), by appropriately adjusting the etching conditions, the metal portion located on the surface of the resin surface 18a can be removed to a greater thickness than the metal portion located on the inner lead surface 51a.

[0098] According to this modification, the sealing resin 23 enters the space surrounded by the die pad side surface 11c, the resin surface 18a, and the inner lead tip surface 51c. This allows the inner lead tip surface 51c, the resin portion 18, and the sealing resin 23 to adhere closely over a wide area, making it possible to prevent the inner lead tip surface 51c from peeling off from the resin portion 18 and the sealing resin 23.

[0099] (Third Modification) FIG. 12 is a partially enlarged cross-sectional view showing a lead frame 10 according to a third modification. In the lead frame 10 shown in FIG. 12, the roughness of the inner leads 51 and the die pad 11 at the portions thereof that are in close contact with the resin portion 18 is greater than the roughness of the surfaces of the inner leads 51 and the die pad 11. Specifically, the roughness of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c is greater than the roughness of the inner lead surface 51a and the die pad surface 11a. The average roughness Ra of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c may be, for example, 0.15 μm or more and 0.35 μm or less. The average roughness Ra of the inner lead surface 51a and the die pad surface 11a may be, for example, 0.01 μm or more and 0.15 μm or less.

[0100] The roughness of the die pad side surface 11c, inner lead back surface 51b and inner lead tip surface 51c may be rougher or smoother than the roughness of the external terminal surface 17 and die pad back surface 11b.

[0101] When manufacturing the lead frame 10 shown in FIG. 12, the etching conditions when etching the metal substrate 31 from the back surface side (FIG. 7(C)) are made different from the etching conditions when etching the metal substrate 31 from the front surface side (FIG. 7(F)). This makes it possible to make the roughness of the inner leads 51 and the die pad 11 portions that come into close contact with the resin part 18 rougher than the roughness of the front surfaces of the inner leads 51 and the die pad 11. Furthermore, when etching the metal substrate 31 from the back surface side (FIG. 7(C)), a microetching liquid may be supplied to the metal substrate 31 to make the roughness of the inner leads 51 and the die pad 11 portions that come into close contact with the resin part 18 rougher.

[0102] According to this modification, by increasing the roughness of the portions of the inner lead 51 and the die pad 11 that come into close contact with the resin part 18, it is possible to increase the adhesion strength between the inner lead 51 and the die pad 11 and the resin part 18. This makes it possible to prevent the inner lead 51 and the die pad 11 from peeling off from the resin part 18.

[0103] (Fourth Modification) FIG. 13 is a partially enlarged cross-sectional view showing a lead frame 10 according to a fourth modification. In the lead frame 10 shown in FIG. 13, the roughness of the inner leads 51 and the die pad 11 at the portions thereof that are in close contact with the resin portion 18 is the same as the roughness of the surfaces of the inner leads 51 and the die pad 11. Specifically, the roughness of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c is the same as the roughness of the inner lead surface 51a and the die pad surface 11a. The average roughness Ra of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c may be, for example, 0.01 μm or more and 0.15 μm or less. The average roughness Ra of the inner lead surface 51a and the die pad surface 11a may be, for example, 0.01 μm or more and 0.15 μm or less.

[0104] 13, the etching conditions for etching the metal substrate 31 from the back surface side (FIG. 7(C)) are substantially the same as the etching conditions for etching the metal substrate 31 from the front surface side (FIG. 7(F)). This makes the roughness of the portions of the inner leads 51 and the die pad 11 that come into close contact with the resin part 18 the same as the roughness of the surfaces of the inner leads 51 and the die pad 11.

[0105] According to this modification, it is possible to increase the adhesive strength between the inner leads 51 and die pad 11 and the resin part 18, and also to increase the adhesive strength between the inner leads 51 and die pad 11 and the sealing resin 23. This makes it possible to prevent the inner leads 51 and die pad 11 from peeling off from the resin part 18 and the sealing resin 23.

[0106] (Fifth Modification) FIG. 14 is a partially enlarged cross-sectional view showing a lead frame 10 according to a fifth modification. In the lead frame 10 shown in FIG. 14, at the boundary between the inner lead 51 and the resin portion 18, the corner between the inner lead surface 51a and the inner lead tip surface 51c is curved in cross-sectional view. The radius of curvature R1 of the corner between the inner lead surface 51a and the inner lead tip surface 51c in cross-sectional view may be, for example, 1 μm or more and 20 μm or less. Furthermore, at the boundary between the inner lead 51 and the resin portion 18, the corner between the resin surface 18a and the resin side surface 18c is curved in cross-sectional view. At the boundary between the inner lead 51 and the resin portion 18, a boundary recess 57 is formed between the inner lead surface 51a and the resin surface 18a. A portion of the plating layer 25 may penetrate into the boundary recess 57.

[0107] Similarly, at the boundary between the die pad 11 and the resin portion 18, a corner between the die pad surface 11a and the die pad side surface 11c is curved in a cross-sectional view. The radius of curvature R2 of the corner between the die pad surface 11a and the die pad side surface 11c in a cross-sectional view may be, for example, 1 μm or more and 20 μm or less. Furthermore, at the boundary between the die pad 11 and the resin portion 18, a corner between the resin surface 18a and the resin side surface 18c is curved in a cross-sectional view. A boundary recess 57 is formed between the die pad surface 11a and the resin surface 18a at the boundary between the die pad 11 and the resin portion 18. A part of the plating layer 25 may extend into the boundary recess 57.

[0108] 14, when the metal substrate 31 is etched from the front surface side (FIG. 7(F)), the metal substrate 31 is etched until the corner between the inner lead surface 51a (die pad surface 11a) and the resin portion 18 is curved in cross section. As a result, at the boundary between the inner lead 51 (die pad 11) and the resin portion 18, the corner between the inner lead surface 51a and the inner lead tip surface 51c (the corner between the die pad surface 11a and the die pad side surface 11c) is curved in cross section.

[0109] 15, the roughness of the inner lead 51 and the die pad 11 at the portions thereof that come into close contact with the resin portion 18 may be the same as the roughness of the surfaces of the inner lead 51 and the die pad 11. In this case, the roughness of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c is the same as the roughness of the inner lead surface 51a and the die pad surface 11a. The average roughness Ra of the die pad side surface 11c, the inner lead back surface 51b, and the inner lead tip surface 51c may be, for example, 0.01 μm or more and 0.15 μm or less. The average roughness Ra of the inner lead surface 51a and the die pad surface 11a may be, for example, 0.01 μm or more and 0.15 μm or less.

[0110] According to this modification, the sealing resin 23 penetrates into the boundary recess 57 located at the boundary between the inner lead 51 (die pad 11) and the resin part 18, thereby increasing the adhesive strength between the inner lead 51 and the die pad 11 and the sealing resin 23. This makes it possible to prevent the inner lead 51 and the die pad 11 from peeling off from the sealing resin 23.

[0111] (Sixth Modification) FIG. 16 is a partially enlarged cross-sectional view showing a lead frame 10 according to a sixth modified example. In the lead frame 10 shown in FIG. 16, the entire inner lead tip surface 51c is in close contact with the resin portion 18. Inside the inner lead tip surface 51c (the die pad 11 side, the opposite side to the external terminal 53), the resin surface 18a is located closer to the front surface (opposite the resin back surface 18b) than the inner lead surface 51a and the die pad surface 11a. In other words, the resin portion 18 protrudes toward the front surface between the die pad 11 and the inner lead tip surface 51c. The distance L4 between the inner lead surface 51a and the resin surface 18a may be greater than 0 μm and less than or equal to 15 μm, or may be greater than or equal to 2 μm and less than or equal to 10 μm. The distance between the die pad surface 11a and the resin surface 18a may also be equal to the distance L4. Further, inside the inner lead tip surface 51c (the die pad 11 side, opposite the external terminal 53), the resin back surface 18b is located on the same plane as the external terminal surface 17 and the die pad back surface 11b.

[0112] When manufacturing the lead frame 10 shown in Figure 16, when etching the metal substrate 31 from the front side (Figure 7(F)), even after the resin surface 18a inside the inner lead tip surface 51c is exposed, the metal portions corresponding to the inner lead surface 51a and the die pad surface 11a continue to be removed.

[0113] According to this modification, the protruding portion of the resin portion 18 between the die pad 11 and the inner lead tip surface 51c is firmly adhered to the sealing resin 23. This makes it possible to prevent the resin portion 18 and the sealing resin 23 from peeling off from each other.

[0114] (Seventh Modification) FIG. 17 is a cross-sectional view showing a lead frame 10 according to a seventh modified example. The lead frame 10 shown in FIG. 17 includes lead portions 12 and a resin portion 18. The lead frame 10 shown in FIG. 17 does not have a die pad 11. In other words, only the resin portion 18 exists between a pair of opposing inner leads 51 in the longitudinal direction of the inner leads 51. The lead frame 10 may be used to fabricate a flip-chip type semiconductor device. In this case, a semiconductor element 21 (imaginary line) is mounted on the lead portions 12, for example. The semiconductor element 21 is electrically connected to the lead portions 12 via bumps 26 (connecting members).

[0115] According to this modification, the inner leads 51 facing each other can be brought closer to each other in the longitudinal direction of the inner leads 51, thereby making it possible to reduce the size of the semiconductor device.

[0116] (Second embodiment) The second embodiment will be described with reference to Figures 18 to 20. In Figures 18 to 20, the same parts as those in the first embodiment shown in Figures 1 to 17 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0117] (Lead frame configuration) The lead frame according to this embodiment will be outlined with reference to Fig. 18. Fig. 18 is a diagram showing the lead frame according to this embodiment.

[0118] 18, the lead frame 10 includes a die pad 11, a plurality of elongated lead portions 12, and a resin portion 18. An inner lead 51 of the lead portion 12 is thinned from the back surface side. An inner lead tip surface 51c of the inner lead 51 is in close contact with the resin portion 18. A front surface side end 51d of the inner lead tip surface 51c is located more inward than a back surface side end 51e.

[0119] The lead portion 12 has a connection portion 52. The connection portion 52 is located outside (on the support lead 13 side) of the external terminal 53. The connection portion 52 is thinned from the back surface side. The connection portion 52 extends from the external terminal 53 toward the support lead 13, and its base end is connected to the support lead 13. The connection portion 52 is a portion that connects the lead portion 12 to the support lead 13. The connection portion 52 is located within each package area 10a. The connection portion 52 is located between the external terminal 53 and the lead connecting portion 16.

[0120] In this embodiment, the recess 19 located on the back surface of the lead connection portion 16 is not filled with the resin portion 18, and the metal surface is exposed. The recess 19 is formed on the back surface of the lead portion 12, outside the external terminal surface 17. The recess 19 is formed by thinning the back surface by half-etching. The recess 19 is a non-penetrating recess that recesses from the back surface side of the lead portion 12 and the lead connection portion 16 to the middle of the thickness direction (Z direction). The front surface side of the recess 19 is not thinned and is located on the same plane as the die pad surface 11a and the inner lead surface 51a. The recess 19 may be formed across the entire width of the connection portion 52 and the lead connection portion 16. In this case, the recess 19 may be formed on the part of the back surface of the connection portion 52 outside the external terminal surface 17 and on the entire back surface of the lead connection portion 16.

[0121] (Configuration of semiconductor device) 19 is a cross-sectional view showing a state in which the semiconductor device 20 according to the present embodiment is connected to a wiring substrate 80. The semiconductor device 20 shown in FIG. 19 is fabricated from the lead frame 10 shown in FIG.

[0122] As shown in FIG. 19, a semiconductor device (semiconductor package) 20 includes a die pad 11, a plurality of leads 12, a resin portion 18, a semiconductor element 21, a plurality of bonding wires (connecting members) 22, and a sealing resin 23. A recess 19a is formed on the back surface of each lead 12 at a position corresponding to the outer periphery of the semiconductor device 20. The recess 19a is a part of the recess 19 described above. Each recess 19a is formed on the lead 12 outside the external terminal surface 17. The recess 19a opens to the back surface side of the lead 12 and also opens to the side surface of the lead 12. The sealing resin 23 and the resin portion 18 are not filled in the recess 19a.

[0123] 19, the semiconductor device 20 is connected to a wiring board 80. A back surface 11b of the die pad 11 is connected to the wiring board 80 by a solder portion 81. The solder plating provided on the external terminal surface 17 and the recess 19a of the lead portion 12 forms a solder fillet 82.

[0124] (Lead frame manufacturing method) Next, a method for manufacturing the lead frame 10 shown in FIG. 18 will be described with reference to FIGS. 20(A) to 20(G).

[0125] First, a flat metal substrate 31 is prepared in substantially the same manner as in the step shown in FIG. 7(A) (FIG. 20(A)).

[0126] Next, etching resist layers 32 and 33 are formed on the metal substrate 31 in substantially the same manner as in the step shown in FIG. 7(B) (FIG. 20(B)).

[0127] 7(C) , the metal substrate 31 is subjected to etching (FIG. 20(C)), thereby thinning the metal substrate 31 from the rear surface side thereof to the middle of the thickness direction, and forming rear surface side recesses 36 and 37.

[0128] Next, the region corresponding to the rear surface side recess 37 is covered with a partial opening mask 39 (FIG. 20(D)). The partial opening mask 39 may be, for example, a metal mask or a screen printing mask.

[0129] Next, in substantially the same manner as the step shown in Fig. 7(D), resin portion 18 is formed on the back surface side of metal substrate 31 (Fig. 20(D)). At this time, resin portion 18 covers the area of ​​the back surface of metal substrate 31 that is not covered by partial opening mask 39. As a result, resin portion 18 fills back surface side recess 36. Resin portion 18 does not fill back surface side recess 37.

[0130] 7(F), the etching resist layer 32 on the front surface side is removed. Next, half etching is performed to thin the entire surface of the metal substrate 31 from the front surface side to partway in the thickness direction (FIG. 20(E)). The partial opening mask 39 is also removed. This forms the outlines of the die pad 11 and the lead portion 12. In addition, a recess 19 that is not filled with the resin portion 18 is formed at a position corresponding to the rear surface side recess 37.

[0131] Next, in substantially the same manner as in the step shown in FIG. 7(E), the resin portion 18 is polished to a predetermined thickness to expose the rear surface of the metal substrate 31 (FIG. 20(F)).

[0132] 20(E) may be a step of polishing the surface of the metal substrate 31. Alternatively, the step of thinning the surface of the metal substrate 31 may be a step of polishing the surface of the metal substrate 31 after half-etching the surface of the metal substrate 31. Polishing the surface of the metal substrate 31 may be performed simultaneously with polishing the resin portion 18 (FIG. 20(F)), or may be performed at a different timing from polishing the resin portion 18 (FIG. 20(F)). In this case, the positions of the resin portion 18 and the metal portion exposed on the surface can be adjusted as needed.

[0133] 7(G), plating layers 25 are formed at predetermined positions on the die pad 11 and the lead portions 12. In this manner, the lead frame 10 shown in FIG. 20 is obtained (FIG. 20(G)).

[0134] According to this embodiment, as shown in Fig. 19, the inside of the recess 19a is filled with the solder fillet 82. This makes it easy to confirm from the outside that the lead portion 12 and the wiring board 80 are connected during a visual inspection.

[0135] It is also possible to combine the multiple components disclosed in the above embodiments and modifications as needed, or to delete some of the components disclosed in the above embodiments and modifications. [Explanation of symbols]

[0136] 10 Lead Frame 11 Die pad 12 Lead section 15 Internal terminal 17 External terminal surface 18 Resin part 25 plating layer 51 Inner Lead 51a Inner lead surface 51b Inner lead back side 51c Inner lead tip surface 51d Front side edge 51e Back side end 53 External terminal 53a External terminal surface

Claims

1. In the lead frame, A lead portion and a resin portion disposed around the lead portion, the lead portion has an inner lead having an inner lead tip surface formed at its tip, and an external terminal having an external terminal surface, the inner lead is thinned from the rear surface side, and at least a part of the tip surface of the inner lead is in close contact with the resin portion; A lead frame in which the front surface side end of the tip surface of the inner lead is located more inward than the back surface side end of the tip surface of the inner lead.

2. 2. The lead frame according to claim 1, wherein in a cross section along the longitudinal direction of said inner lead, the tip end surface of said inner lead is linearly inclined from said front surface side end toward said back surface side end.

3. 2. The lead frame according to claim 1, wherein in a cross section along the longitudinal direction of the inner lead, the tip end surface of the inner lead curves outward from the front surface end toward the back surface end.

4. 2. The lead frame according to claim 1, wherein the surface of the resin portion is located on a back side of the surface of the inner lead inside the tip end surface of the inner lead.

5. 2. The lead frame according to claim 1, further comprising a die pad, wherein the surface of the resin portion is located on a backside of the surface of the die pad between the die pad and the tip surface of the inner lead.

6. 2. The lead frame according to claim 1, wherein a surface of the resin portion is located closer to the surface of the inner lead than the surface of the inner lead, inside the tip end surface of the inner lead.

7. 7. The lead frame according to claim 6, wherein the back surface of the resin portion is located on the same plane as the external terminal surface inside the tip end surface of the inner lead.

8. 2. The lead frame according to claim 1, wherein the roughness of the portion of said inner lead that is in close contact with said resin portion is greater than the roughness of the surface of said inner lead.

9. 2. The lead frame according to claim 1, wherein the roughness of the portion of said inner lead that is in close contact with said resin portion is the same as the roughness of the surface of said inner lead.

10. 2. The lead frame according to claim 1, wherein a corner between a surface of the inner lead and a tip end surface of the inner lead is curved in a cross-sectional view at a boundary between the inner lead and the resin portion.

11. 2. The lead frame according to claim 1, wherein a boundary recess is formed at a boundary between said inner lead and said resin portion.

12. 2. The lead frame according to claim 1, wherein the lead portion has a connection portion located outside the external terminal, a recess is formed on the back surface of the connection portion, and the resin portion is not filled in the recess.

13. In a method for manufacturing a lead frame, providing a metal substrate; forming a backside recess on a backside of the metal substrate; forming a resin portion on the metal substrate and covering the rear surface side recess with the resin portion; removing the resin portion from the rear surface side by a predetermined thickness; and forming a lead portion by thinning the metal substrate from the front surface side, the lead portion has an inner lead having an inner lead tip surface formed at its tip, and an external terminal having an external terminal surface, the inner lead is thinned from the rear surface side, and at least a part of the tip surface of the inner lead is in close contact with the resin portion; A method for manufacturing a lead frame, wherein a front surface side end of the tip surface of the inner lead is positioned more inward than a back surface side end of the tip surface of the inner lead.

Images