Method for manufacturing a lead frame, and method for manufacturing a semiconductor device.

Abstract

To provide a lead frame and a method for manufacturing the same which can enhance adhesion between a sealing resin and a lead frame, and a semiconductor device and a method for manufacturing the same.SOLUTION: A lead frame 10 includes a die pad 11, lead parts 12A, 12B and 12C having terminal parts 53A, 53B and 53C, and a back face side resin 18 which is arranged on a back face side of the lead frame 10. The terminal parts 53A, 53B and 53C have a terminal surface 53a, a terminal back face 53b and a terminal side face 53c, and a width wb of the terminal back face 53b is wider than a width wa of the terminal surface 53a. The terminal side face 53c has a first terminal side face 53d positioned on a surface side, and a second terminal side face 53e positioned on a back face side, the second terminal side face 53e is brought into close contact with the back face side resin 18, and the first terminal side face 53d is exposed to outside and is roughened.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This disclosure relates to a lead frame and a method for manufacturing the same, as well as a semiconductor device and a method for manufacturing the same. [Background technology]

[0002] In recent years, there has been a growing demand for miniaturization and thinning of semiconductor devices mounted on substrates. To meet these demands, various so-called QFN (Quad Flat Non-lead) type semiconductor devices have been proposed, which conventionally use a lead frame, encapsulate the semiconductor elements mounted on its mounting surface with sealing resin, and leave a portion of the leads exposed on the back side.

[0003] However, conventionally, as lead frames become thinner, it becomes difficult to maintain their strength, and deformation of the lead frame after etching becomes a problem.

[0004] In recent years, there has been a growing demand to increase the number of leads (pins) without changing the chip size. Traditionally, this has been addressed by narrowing the width of the leads. However, as the leads become narrower, they become more susceptible to deformation, making stable wire bonding difficult. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-57590 [Overview of the project] [Problems that the invention aims to solve]

[0006] Patent Document 1 discloses a technique for removing excess resin from the back surface of a lead frame after providing a resin portion on the back surface. When manufacturing a semiconductor device using such a lead frame with a resin portion on the back surface, there is a need to further improve the adhesion between the sealing resin and the lead frame.

[0007] This disclosure provides a lead frame and a method for manufacturing the same, as well as a semiconductor device and a method for manufacturing the same, which can improve the adhesion between the sealing resin and the lead frame in a lead frame having a resin on the back side. [Means for solving the problem]

[0008] The lead frame according to this disclosure comprises a die pad, a lead portion having a terminal portion and arranged around the die pad, and a back side resin arranged around the die pad and the lead portion on the back side of the lead frame, wherein the terminal portion has a terminal surface located on the front side, a terminal back surface located on the back side, and a terminal side surface located between the terminal surface and the terminal back surface, the width of the terminal back surface of the terminal portion is wider than the width of the terminal surface of the terminal portion, the terminal side surface has a first terminal side surface located on the front side and a second terminal side surface located on the back side, the second terminal side surface is in close contact with the back side resin, and the first terminal side surface is exposed outward and roughened.

[0009] In the lead frame according to this disclosure, the die pad has a die pad surface located on the front side, a die pad back surface located on the back side, a first die pad side facing the lead portion and located on the die pad surface side, and a second die pad side facing the lead portion and located on the die pad back side, wherein the second die pad side is in close contact with the back side resin, and the die pad surface and the first die pad side are exposed to the outside and may be roughened.

[0010] In the lead frame according to this disclosure, the lead portion has an inner lead connected to the terminal portion, the inner lead is thinned from the back side, the inner lead has an inner lead surface located on the front side, an inner lead back surface located on the back side, and an inner lead side surface located between the inner lead surface and the inner lead back surface, the inner lead back surface is in close contact with the back side resin, the inner lead surface and the inner lead side surface are exposed to the outside and may be roughened.

[0011] In the lead frame according to this disclosure, the terminal portion has a lateral projection that protrudes laterally from the terminal side surface, the first terminal side surface may be located on the terminal surface side of the lateral projection, and the second terminal side surface may be located on the terminal back side of the lateral projection.

[0012] The semiconductor device according to this disclosure is a semiconductor device comprising: a die pad; a lead portion disposed around the die pad and having a terminal portion; a back-side resin disposed around the die pad and the lead portion on the back side of the semiconductor device; a semiconductor element mounted on the die pad; a connecting member for electrically connecting the semiconductor element and the lead portion; and a sealing resin for sealing the die pad, the lead portion, the semiconductor element, and the connecting member, wherein the terminal portion has a terminal surface located on the front side, a terminal back surface located on the back side, and a terminal side surface located between the terminal surface and the terminal back surface, the width of the terminal back surface of the terminal portion is wider than the width of the terminal surface of the terminal portion, and the terminal side surface has a first terminal side surface located on the front side and a second terminal side surface located on the back side, the second terminal side surface is in close contact with the back-side resin, and the first terminal side surface is in close contact with the sealing resin and is roughened.

[0013] The method for manufacturing a lead frame according to this disclosure comprises the steps of: preparing a metal substrate; forming a recess on the back side by etching the metal substrate from the back side to a certain point in the thickness direction; forming a resin on the back side of the metal substrate and covering the recess on the back side with the resin; and exposing the resin on the back side to the front side by etching the metal substrate from the front side to a certain point in the thickness direction, thereby forming a die pad and a lead portion arranged around the die pad and having a terminal portion. The process comprises the steps of forming, removing the resin on the back side by a predetermined thickness, and roughening the surface side of the metal substrate, wherein the terminal portion has a terminal surface located on the front side, a terminal back side located on the back side, and a terminal side located between the terminal surface and the terminal back side, the width of the terminal back side of the terminal portion is wider than the width of the terminal surface of the terminal portion, the terminal side has a first terminal side located on the front side and a second terminal side located on the back side, the second terminal side is in close contact with the resin on the back side, and the first terminal side is exposed to the outside and is roughened.

[0014] The method for manufacturing a semiconductor device according to the present disclosure comprises the steps of: preparing a lead frame according to the present disclosure; mounting a semiconductor element on the die pad; electrically connecting the semiconductor element and the lead portion with a connecting member; and sealing the lead frame, the semiconductor element and the connecting member with a sealing resin. [Effects of the Invention]

[0015] According to this disclosure, in a lead frame having a resin on the back side, the adhesion between the sealing resin and the lead frame can be improved. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a plan view showing a lead frame according to one embodiment. [Figure 2] Figure 2 is a bottom view showing a lead frame according to one embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing a lead frame according to an embodiment (cross-sectional view taken along line III-III of FIG. 1). [Figure 4] FIG. 4 is a cross-sectional view showing a lead frame according to an embodiment (cross-sectional view taken along line IV-IV of FIG. 1). [Figure 5] FIG. 5 is a plan view showing a semiconductor device according to an embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a semiconductor device according to an embodiment (cross-sectional view taken along line VI-VI of FIG. 5). [Figure 7] FIGS. 7(a)-(j) are cross-sectional views showing a method of manufacturing a lead frame according to an embodiment. [Figure 8] FIGS. 8(a)-(e) are cross-sectional views showing a method of manufacturing a semiconductor device according to an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment will be described with reference to FIGS. 1 to 8. In the following figures, the same parts are denoted by the same reference numerals, and some detailed descriptions may be omitted.

[0018] In this specification, the X direction and the Y direction are two directions parallel to the sides of the lead frame 10, and 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. Also, “inside” and “inner side” refer to the side facing the center direction of each package region 10a, and “outside” and “outer side” refer to the side away from the center of each package region 10a. Further, “surface” refers to the surface on the side where the semiconductor element 21 is mounted (Z direction plus side), and “back surface” refers to the surface on the opposite side of the “surface” (Z direction minus side) and is the side connected to an external wiring board not shown in the figure.

[0019] Furthermore, in this specification, half-etching refers to etching the material to be etched in its thickness direction up to a certain point. The thickness of the material to be etched after half-etching is, for example, 30% to 70%, preferably 40% to 60%, of the thickness of the material to be etched before half-etching.

[0020] (Lead frame configuration) First, the outline of the lead frame according to this embodiment will be explained with reference to Figures 1 to 4. Figures 1 to 4 are diagrams showing the lead frame according to this embodiment.

[0021] As shown in Figures 1 and 2, the lead frame 10 includes an outer frame 40 and a package area (unit lead frame) 10a located inside the outer frame 40.

[0022] In this case, multiple package regions 10a are arranged in multiple rows and rows (in a matrix). However, it is not limited to this arrangement; one or more package regions 10a are sufficient. Each package region 10a corresponds to a semiconductor device 20 (described later) and is located inside the dotted lines in Figures 1 and 2. The dotted lines in Figures 1 and 2 correspond to the outer edge of the semiconductor device 20.

[0023] Next, the configuration of the lead frame 10 will be further explained with reference to Figures 1 to 3.

[0024] As shown in Figures 1 to 3, each package region 10a of the lead frame 10 comprises a die pad 11, a plurality of elongated lead portions 12A, 12B, and 12C provided around the die pad 11 to connect a semiconductor element 21 (described later) and an external circuit (not shown), and a back-side resin 18 located around the die pad 11 and the lead portions 12A, 12B, and 12C, and positioned on the back side of the lead frame 10. The plurality of package regions 10a are connected to each other via support leads (support members) 13. These support leads 13 support the die pad 11 and the lead portions 12A, 12B, and 12C, and extend along the X and Y directions, respectively.

[0025] In this embodiment, the surface side of the lead frame 10 is roughened. Specifically, of the die pad 11, lead portion 12, support lead 13, and outer frame 40 of the lead frame 10, the portions on the surface side of the back side resin 18 and that do not come into contact with the back side resin 18 are roughened.

[0026] This roughened portion is formed by roughening the surface of the metal substrate 31 (for example, by micro-etching), as will be described later. That is, the roughness of the roughened portion of the lead frame 10 is rougher than the roughness of the unroughened portion of the lead frame 10. The average roughness of the roughened portion can be, for example, Ra = 0.03 μm or more and 0.6 μm or less. The average roughness Ra is the arithmetic mean roughness as defined in JIS B0601. In Figures 1 and 2, the roughened portion is shown with shading (the same applies to Figure 5, which will be described later). Also, in Figure 3, the roughened portion is shown with a thick dashed line (the same applies to Figures 4, 6 to 8, which will be described later).

[0027] The die pad 11 has a planar shape that is approximately square. In this case, the die pad 11 is not half-etched and has the same thickness as the metal substrate before processing (metal substrate 31 described later). The planar shape of the die pad 11 is not limited to a square, but may be a polygon such as a rectangle. The die pad 11 is not connected to a suspension lead, and the die pad 11 is supported by the support lead 13 or the outer frame 40 only via the resin 18 on the back side. In this case, for example, other lead parts (not shown) may be placed in the area near the corners of the die pad 11. This allows for effective use of the area near the corners of the die pad 11. However, the die pad 11 may also be supported by the support lead 13 or the outer frame 40 via the suspension lead.

[0028] As shown in Figure 3, the die pad 11 has a die pad surface 11a located on the front side and a die pad back surface 11b located on the back side. A semiconductor element 21, which will be described later, is mounted on the die pad surface 11a. The die pad back surface 11b is exposed outward from the lead frame 10. In addition, a first die pad side surface 11c and a second die pad side surface 11d are formed on the side of the die pad 11 facing the lead portions 12A, 12B, and 12C. The first die pad side surface 11c is located on the die pad surface 11a side and is exposed outward from the lead frame 10. The second die pad side surface 11d is located on the die pad back surface 11b side and is in close contact with the back side resin 18. In this case, the die pad surface 11a and the first die pad side surface 11c of the die pad 11 are roughened. On the other hand, the die pad back surface 11b and the second die pad side surface 11d of the die pad 11 are not roughened.

[0029] Next, the configuration of lead sections 12A, 12B, and 12C will be explained. Note that lead sections 12A, 12B, and 12C are also referred to as the first lead section 12A, the second lead section 12B, and the third lead section 12C, respectively.

[0030] Each of the lead portions 12A, 12B, and 12C is connected to the semiconductor element 21 via a bonding wire 22, as will be described later, and is positioned with a space between it and the die pad 11. Each of the lead portions 12A, 12B, and 12C extends from either the support lead 13 or the outer frame 40.

[0031] As shown in Figure 1, each first lead portion 12A has a first terminal portion 53A and an inner lead 51A connected to the first terminal portion 53A. The inner lead 51A extends inward (towards the die pad 11) from the first terminal portion 53A, and its tip is positioned spaced apart from the die pad 11. The first terminal portion 53A is directly connected to the support lead 13 or the outer frame 40.

[0032] Each second lead section 12B has a second terminal section 53B, an inner lead 51B connected to the second terminal section 53B, and a connecting lead 52B connected to the second terminal section 53B. The inner lead 51B extends inward from the second terminal section 53B (towards the die pad 11), and its tip is positioned spaced apart from the die pad 11. The connecting lead 52B extends outward from the second terminal section 53B (towards the support lead 13 or outer frame 40), and is connected to the support lead 13 or the outer frame 40.

[0033] Each third lead section 12C has a third terminal section 53C, an inner lead 51C connected to the third terminal section 53C, and a connecting lead 52C connected to the third terminal section 53C. The inner lead 51C extends inward from the third terminal section 53C (towards the die pad 11), and its tip is positioned spaced apart from the die pad 11. The connecting lead 52C extends outward from the third terminal section 53C (towards the support lead 13 or outer frame 40), and is connected to the support lead 13 or outer frame 40.

[0034] An inner lead tip surface 51d is formed at the tip (die pad 11 side end) of the inner leads 51A, 51B, and 51C of the lead sections 12A, 12B, and 12C, respectively (Figure 3). The inner lead tip surfaces 51d are positioned opposite the second die pad side surface 11d of the die pad 11. The inner lead tip surfaces 51d are not covered by the back side resin 18, and a space is formed between the inner lead tip surfaces 51d and the second die pad side surface 11d.

[0035] Furthermore, internal terminals 15 are formed on the surface of the tip portions (die pad 11 side ends) of the inner leads 51A, 51B, and 51C of the lead portions 12A, 12B, and 12C, respectively. These internal terminals 15 are regions that are electrically connected to the semiconductor element 21 via bonding wires 22, as will be described later. For this reason, a plating layer 25 is provided on the internal terminals 15 to improve adhesion with the bonding wires 22. The plating layer 25 may be made of silver plating, for example. In addition, the internal terminals 15 of the lead portions 12A, 12B, and 12C are arranged along straight lines parallel to the sides of the die pad 11. This makes it possible to improve the efficiency of the bonding work.

[0036] The adjacent lead portions 12A and 12B, lead portions 12B and 12C, and lead portions 12C and 12A are shaped to be electrically insulated from each other after the semiconductor device 20 (described later) is manufactured. In addition, each lead portion 12A, 12B, and 12C is shaped to be electrically insulated from the die pad 11 after the semiconductor device 20 is manufactured.

[0037] As shown in Figure 2, external terminals 17A, 17B, and 17C are formed on the back surfaces of terminals 53A, 53B, and 53C, respectively, which are electrically connected to an external mounting substrate (not shown). Each of the external terminals 17A, 17B, and 17C is exposed to the outside of the semiconductor device 20 (described later) after the semiconductor device 20 is manufactured.

[0038] The inner leads 51A, 51B, 51C and connecting leads 52B, 52C of the lead portions 12A, 12B, 12C are each formed thinly by half-etching from the back side. On the other hand, the terminal portions 53A, 53B, 53C are not half-etched and have the same thickness as the die pad 11. In this way, by making the thickness of the inner leads 51A, 51B, 51C and connecting leads 52B, 52C thinner than the thickness of the terminal portions 53A, 53B, 53C, narrow lead portions 12A, 12B, 12C can be formed with high precision, and a small semiconductor device 20 with a large number of pins can be obtained. In this embodiment, the first lead portion 12A does not have a connecting lead, but it is not limited to this, and the first lead portion 12A may have a connecting lead that is formed thinly by half-etching from the back side.

[0039] As shown in Figure 1, the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C are each supported by the support lead 13 and are arranged repeatedly in this order along the support lead 13. That is, in this embodiment, the third lead portion 12C, the second lead portion 12B, and the first lead portion 12A are arranged repeatedly in this order from the longitudinal end of the support lead 13 toward the longitudinal center. However, this is not the only option; the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C may also be arranged repeatedly in this order from the longitudinal end of the support lead 13 toward the longitudinal center.

[0040] Furthermore, a first lead portion 12A is provided at the longitudinal center of the support lead 13. From the central first lead portion 12A, the second lead portion 12B, the first lead portion 12A, and the third lead portion 12C are repeatedly arranged in this order toward both ends in the longitudinal direction of the support lead 13. In this case, the multiple first lead portions 12A, the multiple second lead portions 12B, and the multiple third lead portions 12C supported by the support lead 13 are arranged symmetrically with respect to the longitudinal center of the support lead 13. Specifically, both the shape and arrangement of the lead portions 12A, 12B, and 12C on either side of the central first lead portion 12A are symmetrical with respect to the center. This allows for a well-balanced arrangement of the terminal portions 53A, 53B, and 53C, facilitating the design and manufacture of the semiconductor device 20.

[0041] As shown in Figure 1, the terminal portions 53A, 53B, and 53C of the multiple lead portions 12A, 12B, and 12C are arranged in a staggered pattern when viewed from a plane. In this case, the multiple terminal portions 53A, 53B, and 53C are arranged in three rows along a straight line parallel to either the X or Y direction. That is, the centers of the multiple terminal portions 53A, 53B, and 53C are along the straight line L. A , L B , L C They are arranged along the line L. A , L B The distance D1 between them and the line L B , L C The distance D2 between them is equal to the distance between them (D1 = D2).

[0042] The first terminal portion 53A of the first lead portion 12A is located outside (towards the support lead 13) of the second terminal portion 53B of the second lead portion 12B. Also, the second terminal portion 53B of the second lead portion 12B is located outside (towards the support lead 13) of the third terminal portion 53C of the third lead portion 12C. This ensures a pitch between the terminal portions 53A, 53B, and 53C, thereby preventing contact between the terminal portions 53A, 53B, and 53C and adjacent lead portions 12A, 12B, and 12C.

[0043] Note that the lead sections 12A, 12B, and 12C do not necessarily have inner leads 51A, 51B, and 51C, respectively. In this case, the lead sections 12A, 12B, and 12C may extend from the support lead 13 towards the die pad 11 and be terminated at terminal sections 53A, 53B, and 53C, respectively.

[0044] Next, the cross-sectional shapes of the lead portions 12A, 12B, and 12C will be described with reference to Figure 4. Figure 4 shows the cross-sections of the lead portions 12A, 12B, and 12C along the line IV-IV in Figure 1.

[0045] As shown in Figure 4, the inner lead 51A of the first lead portion 12A is thinned from the back side. The inner lead 51A of the first lead portion 12A has a shape that is substantially symmetrical in cross-section. The inner lead 51A has an inner lead surface 51a located on the front side, an inner lead back surface 51b located on the back side, and a pair of inner lead side surfaces 51c located between the inner lead surface 51a and the inner lead back surface 51b. Of these, the inner lead surface 51a is located on the same plane as the die pad surface 11a of the die pad 11. The inner lead back surface 51b is a surface formed by half etching. This inner lead back surface 51b is located on the front side (positive Z direction side) than the die pad back surface 11b of the die pad 11 and is in close contact with the back side resin 18. The pair of inner lead side surfaces 51c each have a shape that is recessed inward in the width direction of the inner lead 51A. Each inner lead side surface 51c is exposed to the outside without being covered by the back side resin 18.

[0046] In this case, the inner lead surface 51a and the inner lead side surface 51c of the inner lead 51A that are not covered by the plating layer 25 are roughened. The inner lead tip surface 51d is also roughened (see Figure 3). On the other hand, the inner lead surface 51a and the inner lead back surface 51b that are covered by the plating layer 25 are not roughened. However, this is not limited to this, and the entire inner lead surface 51a other than the part covered by the plating layer 25 may also be roughened.

[0047] Although not shown, the cross-sectional shapes along the width direction of the inner lead 51B of the second lead portion 12B and the inner lead 51C of the third lead portion 12C are substantially the same as the cross-sectional shape of the inner lead 51A of the first lead portion 12A shown in FIG. 4.

[0048] Also, as shown in FIG. 4, the second terminal portion 53B of the second lead portion 12B has a shape that is symmetric in the width direction in cross-section. This second terminal portion 53B has a terminal surface 53a located on the front surface side, a terminal back surface 53b located on the back surface side, a pair of terminal side surfaces 53c located between the terminal surface 53a and the terminal back surface 53b, and a pair of side protrusions 53f protruding laterally from the terminal side surfaces 53c, respectively. This second terminal portion 53B has the same thickness as the die pad 11, and the terminal surface 53a and the terminal back surface 53b of the second terminal portion 53B are located on the same plane as the die pad surface 11a and the die pad back surface 11b of the die pad 11, respectively. Note that an external terminal 17B is formed on the terminal back surface 53b of the second terminal portion 53B.

[0049] Each terminal side surface 53c has a first terminal side surface 53d located closer to the terminal surface 53a side than the side protrusion 53f and a second terminal side surface 53e located closer to the terminal back surface 53b side than the side protrusion 53f. Each first terminal side surface 53d extends from the side protrusion 53f to the terminal surface 53a, and each second terminal side surface 53e extends from the side protrusion 53f to the terminal back surface 53b. The first terminal side surface 53d and the second terminal side surface 53e are each curved toward the inner side in the width direction of the second lead portion 12B. Also, each first terminal side surface 53d is inclined so that the width of the second terminal portion 53B widens from the terminal surface 53a side toward the side protrusion 53f side.

[0050] In this case, the width w of the terminal back surface 53b of the second terminal portion 53B b is the width w of the terminal surface 53a of the second terminal portion 53B aThis is wider than the previous one. As a result, even when the spacing between the adjacent first lead portion 12A, second lead portion 12B, and third lead portion 12C is narrowed, a larger area of ​​the external terminal 17B can be secured, and the external terminal 17B can be reliably connected to an external mounting board (not shown). In addition, the width w between the lateral protrusions 53f of the second terminal portion 53B f The width w of the terminal surface 53a of the second terminal portion 53B. a It is wider than that. Note that the width w between the lateral protrusions 53f of the second terminal portion 53B. f The width w of the back surface 53b of the second terminal section 53B. b It can be wider or narrower.

[0051] In this case, the terminal surface 53a and the first terminal side surface 53d of the second terminal portion 53B are roughened. On the other hand, the terminal back surface 53b and the second terminal side surface 53e of the second terminal portion 53B are not roughened. By roughening the first terminal side surface 53d of the second terminal portion 53B in this way, the adhesion between the second terminal portion 53B and the sealing resin 23 described later is improved, and the second lead portion 12B is prevented from falling off the sealing resin 23. In particular, the width w of the terminal back surface 53b of the second terminal portion 53B b The width of the terminal surface 53a is w a Even if the second terminal portion 53B is wider and has a shape that makes it easy for it to detach from the sealing resin 23 to the back side, the detachment of the second terminal portion 53B can be suppressed because the first terminal side surface 53d of the second terminal portion 53B is roughened.

[0052] Although not shown in the figures, the cross-sectional shapes along the width direction of the first terminal portion 53A of the first lead portion 12A and the third terminal portion 53C of the third lead portion 12C are substantially the same as the cross-sectional shapes of the second terminal portion 53B of the second lead portion 12B shown in Figure 4.

[0053] As shown in Figure 4, the connecting lead 52C of the third lead portion 12C is thinned from the back side. The connecting lead 52C of the third lead portion 12C has a substantially symmetrical shape in cross-section. The connecting lead 52C has a connecting lead surface 52a located on the front side, a connecting lead back surface 52b located on the back side, and a pair of connecting lead side surfaces 52c located between the connecting lead surface 52a and the connecting lead back surface 52b. Of these, the connecting lead surface 52a is located on the same plane as the die pad surface 11a of the die pad 11. The connecting lead back surface 52b is a surface formed by half etching. This connecting lead back surface 52b is located on the front side (positive Z direction) than the die pad back surface 11b of the die pad 11 and is in close contact with the resin surface 18a of the back side resin 18. The pair of connecting lead side surfaces 52c each have a shape that is recessed inward in the width direction of the connecting lead 52C. Each connecting lead side surface 52c is exposed to the outside without being covered by the back side resin 18.

[0054] In this case, the surface 52a and the side surface 52c of the connecting lead 52C are roughened. On the other hand, the back surface 52b of the connecting lead 52C is not roughened.

[0055] Although not shown in the diagram, the cross-sectional shape of the connecting lead 52C of the third lead section 12C along the width direction is substantially the same as the cross-sectional shape of the connecting lead 52B of the second lead section 12B.

[0056] The back side resin 18 is positioned around the die pad 11 and the lead portions 12A, 12B, and 12C. That is, as shown in Figure 1, when viewed from the front side, the back side resin 18 is located in the area surrounded by the four sides of the die pad 11, the multiple lead portions 12A, 12B, and 12C, and the support lead 13 or outer frame 40. Also, as shown in Figure 2, when viewed from the back side, the back side resin 18 is located in the area surrounded by the four sides of the die pad 11, the external terminals 17A, 17B, and 17C of the lead portions 12A, 12B, and 12C, and the support lead 13 or outer frame 40. Note that in Figures 1 and 2, the back side resin 18 is shown in gray (the same applies to Figure 5, which will be described later).

[0057] The back-side resin 18 is located on the back side of the lead frame 10. That is, the back-side resin 18 does not exist on the front side (positive Z-direction side) of the lead frame 10 beyond the midpoint in the thickness direction (Z-direction), but only on the back side (negative Z-direction side) beyond the midpoint in the thickness direction. Note that the above-mentioned midpoint is not limited to the center in the thickness direction of the lead frame 10, but may be located on the front or back side of the center in the thickness direction.

[0058] As shown in Figure 3, the back side resin 18 is located in the region surrounded by the second terminal portion 53B, the inner lead back surface 51b, and the second die pad side surface 11d in a cross-sectional view along the length of the second lead portion 12B. The back side resin 18 is also located in the region surrounded by the terminal portion 53B, the connecting lead back surface 52b, and the support lead 13 or outer frame 40 in a cross-sectional view along the length of the second lead portion 12B.

[0059] As shown in Figure 4, the resin 18 on the back side is located on the back side of the inner lead 51b of the inner lead 51A of the first lead portion 12A, and is in close contact with the inner lead 51b. The same applies to the inner lead 51B of the second lead portion 12B and the inner lead 51C of the third lead portion 12C.

[0060] Furthermore, the back-side resin 18 is located on the back side of the lateral projection 53f of the second terminal portion 53B of the second lead portion 12B, and is in close contact with the second terminal side surface 53e. On the other hand, the back-side resin 18 is not in contact with the first terminal side surface 53d. Therefore, the first terminal side surface 53d is exposed to the outside. The same applies to the first terminal portion 53A of the first lead portion 12A and the third terminal portion 53C of the third lead portion 12C.

[0061] Furthermore, the resin 18 on the back side is located on the back side of the connecting lead 52C of the third lead portion 12C, and is in close contact with the connecting lead 52b. The same applies to the connecting lead 52C of the third lead portion 12C.

[0062] As shown in Figure 3, the back side resin 18 has a resin surface 18a located on the front side and a resin back surface 18b located on the back side. Of these, the resin surface 18a is exposed outward from the space between the first die pad side surface 11c and the inner lead tip surface 51d. The resin back surface 18b is exposed outward from the back side of the lead frame 10. Furthermore, the resin back surface 18b, the die pad back surface 11b, and the external terminals 17A, 17B, and 17C are located on the same plane as each other.

[0063] As the back surface resin 18, a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin can be used. In order to improve the adhesion between the back surface resin 18 and the sealing resin 23 described later, it is preferable to use the same material as the sealing resin 23 for the back surface resin 18.

[0064] The die pads 11 and lead portions 12A, 12B, and 12C of the lead frame 10 described above are made of metals such as copper, copper alloys, and 42 alloys (Fe alloy with 42% Ni). The thickness of the lead frame 10 can be between 80 μm and 250 μm, depending on the configuration of the semiconductor device 20 being manufactured.

[0065] In this embodiment, the lead portions 12A, 12B, and 12C are arranged along all four sides of the die pad 11, but this is not the only option. For example, they may be arranged along only two opposing sides of the die pad 11.

[0066] Furthermore, although this embodiment describes an example where the external terminals 17A, 17B, and 17C of the lead sections 12A, 12B, and 12C are arranged in three staggered rows, the embodiment is not limited to this arrangement. The external terminals may be arranged in one or two rows, or in four or more rows.

[0067] (Configuration of a semiconductor device) Next, the semiconductor device according to this embodiment will be described with reference to Figures 5 and 6. Figures 5 and 6 show the semiconductor device (QFN type) according to this embodiment.

[0068] As shown in Figures 5 and 6, the semiconductor device (semiconductor package) 20 comprises a die pad 11, a plurality of lead portions 12A, 12B, and 12C arranged around the die pad 11, a semiconductor element 21 mounted on the die pad 11, and a plurality of bonding wires (connecting members) 22 that electrically connect the lead portions 12A, 12B, and 12C to the semiconductor element 21. Furthermore, a backside resin 18 is arranged around the die pad 11 and the lead portions 12A, 12B, and 12C on the back side of the semiconductor device 20. In addition, the die pad 11, the lead portions 12A, 12B, and 12C, the semiconductor element 21, and the bonding wires 22 are resin-sealed by a sealing resin 23.

[0069] Of these, the die pad 11, lead portions 12A, 12B, 12C, and the back-side resin 18 are made from the lead frame 10 described above. The configuration of the die pad 11, lead portions 12A, 12B, 12C, and the back-side resin 18 is the same as that shown in Figures 1 to 4 above, except for areas not included in the semiconductor device 20, so a detailed explanation is omitted here.

[0070] In this embodiment, the portions of the die pad 11 and lead portions 12A, 12B, and 12C that are on the surface side of the back side resin 18 and in contact with the sealing resin 23 are roughened. The roughened portions of the die pad 11 and lead portions 12A, 12B, and 12C are the same as those shown in Figures 1 to 4 described above, except for the portions that are not included in the semiconductor device 20.

[0071] Furthermore, the semiconductor element 21 can be any of the semiconductor elements commonly used in the past, and is not particularly limited, but for example, integrated circuits, large-scale integrated circuits, transistors, thyristors, diodes, etc. can be used. This semiconductor element 21 has a plurality of electrodes 21a to which bonding wires 22 are attached. The semiconductor element 21 is fixed to the surface of the die pad 11 by an adhesive 24, such as die bonding paste.

[0072] 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 the electrode 21a of the semiconductor element 21, and the other end is connected to the plating layer 25 located on the internal terminals 15 of each lead portion 12A, 12B, and 12C.

[0073] As the sealing resin 23, a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin can be used. The overall thickness of the sealing resin 23 can be approximately 300 μm to 1200 μm. Also, one side of the sealing resin 23 (one side of the semiconductor device 20) can be, for example, 1 mm to 16 mm. In the space between the die pad 11 and the lead portions 12A, 12B, and 12C, the sealing resin 23 is in close contact with the resin surface 18a of the back side resin 18. Note that in Figure 5, the sealing resin 23 located on the front side of the die pad 11, lead portions 12A, 12B, and 12C and the back side resin 18 is not shown.

[0074] (Manufacturing method for lead frames) Next, the manufacturing method of the lead frame 10 shown in Figures 1 to 4 will be explained using Figures 7(a)-(j).

[0075] First, a flat metal substrate 31 is prepared as shown in Figure 7(a). This metal substrate 31 can be made of a metal such as copper, a copper alloy, or a 42 alloy (a 42% Ni Fe alloy). It is preferable to use a metal substrate 31 that has been degreased and cleaned on both sides.

[0076] Next, a photosensitive resist is applied to both the 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 to form etching resist layers 32 and 33 having the desired openings 32b and 33b (Figure 7(b)).

[0077] Next, the metal substrate 31 is thinned from the back side to a certain point in the thickness direction by half-etching. In this case, the etching resist layer 33 on the back side is used as an corrosion-resistant film, and etching is performed on the back side of the metal substrate 31 with an etching solution (Figure 7(c)). At this time, the etching resist layer 32 on the front side may be covered with a film not shown. This forms a back-side recess 36, which is a non-penetrating recess, on the back side of the metal substrate 31. This back-side recess 36 has a shape corresponding to the back-side resin 18. The etching solution can be appropriately selected depending on the material of the metal substrate 31 used. For example, when copper is used as the metal substrate 31, a ferric chloride aqueous solution is usually used, and this ferric chloride aqueous solution may be spray-etched from one or both sides of the metal substrate 31.

[0078] Next, the etching resist layer 33 on the back side is peeled off, leaving the etching resist layer 32 on the front side, and then the metal substrate 31 is washed with water and dried (Figure 7(d)).

[0079] Next, a backside resin 18 is formed on the back side of the metal substrate 31, and the backside recess 36 is covered with the backside resin 18 (Figure 7(e)). At this time, a thermosetting resin or thermoplastic resin may be injection molded or transfer molded on the back side of the metal substrate 31. As a result, the backside resin 18 is filled into the backside recess 36. The thickness T1 of the backside resin 18 from the portion 11e corresponding to the back side 11b of the die pad may be 25 μm or more and 200 μm or less. In this case, the back side of the metal substrate 31, specifically the portion 11e corresponding to the back side 11b of the die pad and the portion 17a corresponding to the external terminals 17A, 17B, and 17C of the lead portions 12A, 12B, and 12C, is covered with the backside resin 18. At this time, the entire back surface of the metal substrate 31 may be covered with the backside resin 18.

[0080] Next, the metal substrate 31 is thinned from the surface side to a certain point in the thickness direction by half-etching. In this case, the etching resist layer 32 on the surface side is used as a corrosion-resistant film, and etching is performed on the surface side of the metal substrate 31 with an etching solution (Figure 7(f)). This forms the outer shape of the die pad 11, lead portions 12A, 12B, 12C and support lead 13. Furthermore, by half-etching the surface side of the metal substrate 31, a gap is formed between the die pad 11 and the lead portions 12A, 12B, and 12C, exposing the resin 18 on the back side to the surface side. The same etching solution used when etching the back side of the metal substrate 31 can be used as the etching solution (Figure 7(c)).

[0081] Next, the resin 18 on the back side is removed to a predetermined thickness to expose the back surface of the metal substrate 31 (Figure 7(g)). Specifically, the resin 18 on the back side is polished from the back side, and the polishing of the resin 18 on the back side is stopped when the back surface of the metal substrate 31 is exposed. At this time, the metal surfaces constituting the back surface 11b of the die pad 11 and the external terminals 17A, 17B, and 17C of the lead portions 12A, 12B, and 12C are exposed on the back side. As a method for removing the resin 18 on the back side, for example, back grinding, which is the most upstream process in the manufacturing of the semiconductor device 20, is used to finish the semiconductor element 21 to a predetermined thickness.

[0082] Next, the etching resist layer 32 is peeled off, and then the metal substrate 31 is washed with water and dried (Figure 7(h)).

[0083] Next, electroplating is applied to the inner leads 51A, 51B, and 51C of the lead sections 12A, 12B, and 12C. This deposits a metal (for example, silver) onto the inner leads 51A, 51B, and 51C of the lead sections 12A, 12B, and 12C, forming a plating layer 25 on each (Figure 7(i)).

[0084] Subsequently, the surface of the metal substrate 31 is roughened (Figure 7(j)). At this time, the back surface of the metal substrate 31 may be covered with a film (not shown), and a micro-etching solution may be supplied to the surface of the metal substrate 31 to form a rough surface over the entire surface of the metal substrate 31, excluding the portion covered by the plating layer 25. Here, the micro-etching solution is a surface treatment agent that slightly dissolves the metal surface and forms a rough surface with fine irregularities. For example, when roughening a metal substrate 31 made of copper or a copper alloy, a micro-etching solution mainly composed of hydrogen peroxide and sulfuric acid may be used. In this way, the lead frame 10 shown in Figures 1 to 4 is obtained (Figure 7(j)).

[0085] (Method of manufacturing semiconductor devices) Next, the manufacturing method of the semiconductor device 20 shown in Figures 5 and 6 will be explained using Figures 8(a)-(e).

[0086] First, the lead frame 10 is fabricated using the method shown in Figures 7(a)-7(j), for example (Figure 8(a)).

[0087] Next, the semiconductor element 21 is mounted on the die pad 11 of the lead frame 10. In this case, the semiconductor element 21 is placed and fixed on the die pad 11 using an adhesive 24, such as die bonding paste (die attach process) (Figure 8(b)).

[0088] Next, each electrode 21a of the semiconductor element 21 and the plating layer 25 formed on each lead portion 12A, 12B, and 12C are electrically connected to each other by bonding wires (connecting members) 22 (wire bonding process) (Figure 8(c)).

[0089] 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 (Figure 8(d)). In this way, the lead frame 10, the lead portions 12A, 12B, 12C, the semiconductor element 21, and the bonding wire 22 are sealed.

[0090] Next, the lead frame 10 is separated for each semiconductor device 20 by dicing the sealing resin 23 and support leads 13 between each semiconductor element 21. In this case, for example, the sealing resin 23 and support leads 13 between each semiconductor device 20 may be cut while rotating a blade made of a diamond grinding wheel.

[0091] In this way, the semiconductor device 20 shown in Figures 5 and 6 is obtained (Figure 8(e)).

[0092] As described above, according to this embodiment, the terminal sides 53c of the terminal portions 53A, 53B, and 53C are in close contact with the back side resin 18, and the second terminal sides 53e of the terminal portions 53A, 53B, and 53C are roughened without being covered by the back side resin 18. As a result, after the semiconductor device 20 is manufactured, the roughened second terminal sides 53e adhere to the sealing resin 23 with high adhesion strength, thereby preventing the terminal portions 53A, 53B, and 53C from falling off the sealing resin 23. In particular, when the width of the back surface 53b of the terminal portions 53A, 53B, and 53C is wider than the width of the front surface 53a, and the terminal portions 53A, 53B, and 53C have a shape that makes them easily peeled off the sealing resin 23, the roughened second terminal sides 53e adhere to the sealing resin 23. Therefore, it is possible to prevent the terminal portions 53A, 53B, and 53C from falling off the sealing resin 23.

[0093] Furthermore, according to this embodiment, the second die pad side surface 11d of the die pad 11 is in close contact with the back side resin 18, and the die pad surface 11a and the first die pad side surface 11c are exposed to the outside and are roughened. As a result, after the semiconductor device 20 is manufactured, the roughened die pad surface 11a and the first die pad side surface 11c adhere to the sealing resin 23 with high adhesion strength, thereby preventing the die pad 11 from falling off the sealing resin 23.

[0094] Furthermore, according to this embodiment, the inner lead back surface 51b of the inner leads 51A, 51B, and 51C are in close contact with the back side resin 18, while the inner lead surface 51a and inner lead side surface 51c are exposed to the outside and are roughened. As a result, after the semiconductor device 20 is manufactured, the roughened inner lead surface 51a and inner lead side surface 51c adhere to the sealing resin 23 with high adhesion strength, thereby preventing the inner leads 51A, 51B, and 51C from falling off the sealing resin 23.

[0095] Furthermore, according to this embodiment, the terminal portions 53A, 53B, and 53C have lateral projections 53f that protrude laterally from the terminal surface 53a, the first terminal side surface 53d is located closer to the terminal surface 53a than the lateral projection 53f, and the second terminal side surface 53e is located closer to the terminal back surface 53b than the lateral projection 53f. As a result, after the semiconductor device 20 is manufactured, the lateral projections 53f enter the boundary between the sealing resin 23 and the back surface resin 18 and act as anchors, thereby preventing the terminal portions 53A, 53B, and 53C from falling off the sealing resin 23 and the back surface resin 18.

[0096] Furthermore, according to this embodiment, the step of exposing the back side resin 18 to the front side by etching (Figure 7(f)) is performed before the step of removing the back side resin 18 by a predetermined thickness (Figure 7(g)). As a result, when etching the front side of the metal substrate 31, the back side of the metal substrate 31 is covered by the back side resin 18, so that only the front side of the metal substrate 31 can be thinned without providing a separate step of covering the back side of the metal substrate 31 with another material.

[0097] Furthermore, according to this embodiment, the photolithography process for forming the etching resist layers 32 and 33 can be reduced to one step (Figure 7(b)), thus simplifying the manufacturing process of the lead frame 10.

[0098] The multiple components disclosed in each of the above embodiments and variations can be combined as needed. Alternatively, some components may be removed from all the components shown in each of the above embodiments and variations. [Explanation of symbols]

[0099] 10 Lead Frames 10a Package area 11 Die Pad 12A, 12B, 12C lead section 15 Internal terminal 17A, 17B, 17C external terminals 18 Resin on the back side 20 Semiconductor equipment 21 Semiconductor devices 22 Bonding wire (connecting component) 23 Sealing resin 25 Plating layer 51A, 51B, 51C Inner Lead 52B, 52C connecting leads 53A, 53B, 53C terminal section 53a Terminal surface 53b Terminal back side 53c Terminal side 53d 1st terminal side 53e Second terminal side 53f Lateral protrusion

Claims

1. In a method for manufacturing a lead frame, The process of preparing the metal substrate, The process of forming a recess on the back side of the metal substrate, A step of forming a backside resin on the back side of the metal substrate and filling the backside recess with the backside resin to cover the backside recess, A step of forming a lead portion having a terminal portion on the metal substrate by etching the surface side of the metal substrate without covering the back side of the metal substrate with any other material other than the back side resin, A step of exposing the back side of the metal substrate, The process includes a step of roughening the surface side of the metal substrate, A method for manufacturing a lead frame, wherein the step of exposing the back side of the metal substrate is a step prior to the step of roughening the front side of the metal substrate.

2. In a method for manufacturing a lead frame, The process of preparing the metal substrate, The process of forming a recess on the back side of the metal substrate, A step of forming a backside resin on the back side of the metal substrate and filling the backside recess with the backside resin to cover the backside recess, A step of forming a lead portion having a terminal portion on the metal substrate by etching the surface side of the metal substrate without covering the back side of the metal substrate with any other material other than the back side resin, The process includes a step of roughening the surface side of the metal substrate, A method for manufacturing a lead frame, wherein the step of forming a backside resin on the back side of the metal substrate and covering the backside recess with the backside resin is a step prior to the step of roughening the front side of the metal substrate.

3. The process includes forming a die pad on the metal substrate, A method for manufacturing a lead frame according to claim 1 or 2.

4. The terminal portion has a terminal surface located on the front side, a terminal back located on the back side, and a terminal side located between the terminal surface and the terminal back. The terminal side surface has a first terminal side surface located on the front side and a second terminal side surface located on the back side. The side surface of the second terminal is in close contact with the resin on the back surface. The side surface of the first terminal is exposed to the outside and has a roughened surface. A method for manufacturing a lead frame according to any one of claims 1 to 3.

5. The lead portion has an inner lead connected to the terminal portion, and the inner lead is thinned from the back side. The inner lead has an inner lead surface located on the front side, an inner lead back located on the back side, and an inner lead side located between the inner lead surface and the inner lead back. The back surface of the inner lead is in close contact with the resin on the back surface. The method for manufacturing a lead frame according to claim 1 or 2, wherein the inner lead surface and the inner lead side surface are exposed to the outside and are roughened.

6. The die pad has a die pad surface located on the front side, a die pad back located on the back side, and a die pad side located between the die pad surface and the die pad back. The die pad side surface has a first die pad side surface located on the front side and a second die pad side surface located on the back side. The side surface of the second die pad is in close contact with the resin on the back surface. The method for manufacturing a lead frame according to claim 3, wherein the die pad surface and the side surface of the first die pad are exposed to the outside and are roughened.

7. The method for manufacturing a lead frame according to claim 4, wherein the roughness of the side surface of the first terminal is rougher than the roughness of the side surface of the second terminal.

8. The method for manufacturing a lead frame according to claim 5, wherein the roughness of the inner lead surface and the inner lead side surface is rougher than the roughness of the inner lead back surface.

9. The method for manufacturing a lead frame according to claim 6, wherein the roughness of the die pad surface and the side surface of the first die pad is rougher than the roughness of the side surface of the second die pad.

10. In a method for manufacturing a semiconductor device, A step of preparing a lead frame obtained by the manufacturing method described in any one of claims 1 to 9, A step of mounting a semiconductor element on the lead frame, A step of electrically connecting the semiconductor element and the lead frame with a connecting member, A method for manufacturing a semiconductor device, comprising the step of sealing the lead frame, the semiconductor element, and the connecting member with a sealing resin.

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