Lead frame for optical semiconductor device

Abstract

To provide a lead frame for an optical semiconductor device having high reliability.SOLUTION: A lead frame 100 has a metal frame 10 having a first part 11A, and a second part 11B separated from the first part 11A, and a reflector resin 20. The reflector resin 20 has a fixing part 21 contacting the first part 11A and the second part 11B, and an outer periphery part 25 having an opening 26 exposing the first part 11A and the second part 11B. The first part 11A has a first element mounting part 12A exposed to the opening 26, and a first joint part 13A located at an interface between the first part 11A and the fixing part 21. The first joint part 13A includes a first roughened part which has surface roughness larger than surface roughness of the first element mounting part 12A, and is composed of metal, and a first film containing a first organic molecule. The first organic molecule contains a first metal bond group which is chemically bonded to the first roughened part, and a first resin bond group which is chemically bonded to the fixing part 21.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a lead frame for an optical semiconductor device. [Background technology]

[0002] An optical semiconductor device is known that includes a lead frame for an optical semiconductor device, an optical semiconductor element mounted on the lead frame, and an encapsulating resin that encapsulates the optical semiconductor element. The lead frame for an optical semiconductor device includes, for example, a metal frame and a reflector resin that fixes the metal frame and surrounds an element mounting portion of the metal frame.

[0003] Lead frames for optical semiconductor devices with such a structure have problems with the adhesion between the metal frame and the reflector resin. For example, if the reflectivity of the metal frame is increased by reducing the surface irregularities of the metal frame to improve the light-emitting efficiency of the optical semiconductor device, the adhesion between the metal frame and the reflector resin decreases. If the adhesion between the metal frame and the reflector resin decreases, problems such as leakage of the sealing resin from between the metal frame and the reflector resin or peeling between the metal frame and the reflector resin during use may occur.

[0004] Conventionally, a method has been disclosed in which a roughened plating layer is formed on the surface of a metal frame in order to improve adhesion between the metal frame and the reflector resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-17256 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for higher reliability in optical semiconductor devices, such as stricter reliability tests for in-vehicle products. In the method described in Patent Document 1, a roughened plating layer is formed on the surface of the metal frame to improve adhesion between the metal frame and the reflector resin, but simply forming a roughened plating layer on the surface of the metal frame may not be enough to achieve sufficient improvement in reliability.

[0007] Therefore, the present disclosure provides a highly reliable lead frame for an optical semiconductor device. [Means for solving the problem]

[0008] A lead frame for an optical semiconductor device according to one embodiment of the present disclosure includes a metal frame having a first portion and a second portion located on the same plane as the first portion and spaced apart from the first portion; and a reflector resin, wherein the reflector resin has a fixing portion that is located on the same plane as the metal frame and in contact with the first portion and the second portion, and an outer circumferential portion that is located above the metal frame and is molded integrally with the fixing portion, The portion has an opening to expose the first portion and the second portion, the first portion having a first element mounting portion exposed at the opening and a first bonding portion located at the interface between the first portion and the fixing portion, the first bonding portion having a surface roughness greater than that of the first element mounting portion and including a first roughened portion made of metal and a first coating formed on the surface of the first roughened portion and including first organic molecules, the first organic molecules including a first metal bonding group chemically bonding to the first roughened portion and a first resin bonding group chemically bonding to the fixing portion. [Effects of the Invention]

[0009] According to the present disclosure, a highly reliable lead frame for an optical semiconductor device can be provided. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a perspective view of a lead frame according to an embodiment. [Figure 2] FIG. 2 is a plan view of a lead frame according to the embodiment. [Figure 3] FIG. 3 is a partially enlarged view of FIG. [Figure 4] FIG. 4 is a partially enlarged view of FIG. [Figure 5] FIG. 5 is another enlarged partial view of FIG. [Figure 6] FIG. 6 is a partially enlarged view of FIG. [Figure 7A] FIG. 7A is a perspective view of a metal frame according to an embodiment. [Figure 7B] FIG. 7B is a perspective view of the metal frame according to the embodiment. [Figure 8] FIG. 8 is a cross-sectional view of a lead frame according to an embodiment. [Figure 9] FIG. 9 is a partially enlarged view of FIG. [Figure 10] FIG. 10 is a cross-sectional view of an optical semiconductor device according to an embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of a method for manufacturing a lead frame according to an embodiment. [Figure 12] FIG. 12 is a side view for explaining a method for measuring adhesive strength. [Figure 13] FIG. 13 is a diagram showing the results of measuring the adhesive strength. [Figure 14A] FIG. 14A is a perspective view of a metal frame according to the present embodiment for illustrating a first modified example of the arrangement of joints. [Figure 14B] FIG. 14B is a perspective view of the metal frame according to the present embodiment for illustrating a first modified example of the arrangement of the joints. [Figure 15A] FIG. 15A is a perspective view of a metal frame according to the present embodiment for illustrating a second modified example of the arrangement of joints. [Figure 15B] FIG. 15B is a perspective view of the metal frame according to the present embodiment for illustrating a second modified example of the arrangement of the joints. [Figure 16] FIG. 16 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a first modified example of the cross-sectional structure of the metal frame. [Figure 17] FIG. 17 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a second modified example of the cross-sectional structure of the metal frame. [Figure 18] FIG. 18 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a third modified example of the cross-sectional structure of the metal frame. [Figure 19] FIG. 19 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a fourth modified example of the cross-sectional structure of the metal frame. [Figure 20] FIG. 20 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a fifth modified example of the cross-sectional structure of the metal frame. [Figure 21] FIG. 21 is an enlarged cross-sectional view of a lead frame according to an embodiment for illustrating a sixth modified example of the cross-sectional structure of the metal frame. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure will be described below with reference to the drawings. Each of the following embodiments illustrates a specific example of the present disclosure, and the numerical values, shapes, materials, components, component arrangements, and connection configurations are merely examples and do not limit the present disclosure. Various modifications conceivable by those skilled in the art to the present embodiments, as well as other embodiments constructed by combining some of the components of the embodiments, are also included within the scope of the present disclosure, provided they do not deviate from the gist of the present disclosure. Furthermore, among the components in the following embodiments, components not recited in the independent claims are described as optional components. Furthermore, each figure is a schematic diagram and is not necessarily a precise illustration. For example, the thickness direction lengths of layers and films may be exaggerated in each figure for clarity.

[0012] Furthermore, in this disclosure, terms indicating the relationship between elements, terms indicating the shape of elements, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range and a difference of about a few percent.

[0013] Furthermore, in this specification, the terms "upper" and "lower" do not refer to the upper direction (vertically upper) and lower direction (vertically lower) in absolute spatial recognition, but are used as terms defined by the relative positional relationship of the components in the lead frame for an optical semiconductor device and the optical semiconductor device. Specifically, the side of the lead frame for an optical semiconductor device on which an optical semiconductor element is mounted is defined as "upper." The terms "upper surface" and "lower surface" are similar and do not refer to the upper and lower surfaces in absolute spatial recognition. Furthermore, the terms "upper" and "lower" are applied not only to cases where two components are arranged with a gap between them and another component is present between them, but also to cases where two components are arranged closely together and the two components are in contact with each other.

[0014] In this specification and drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. Hereinafter, the Z-axis direction is defined as the thickness direction of the metal frame. The negative side of the Z-axis is defined as "downward," and the positive side of the Z-axis is defined as "upward."

[0015] (Embodiment) Hereinafter, a lead frame for an optical semiconductor device and an optical semiconductor device using the lead frame according to an embodiment will be described. Hereinafter, the lead frame for an optical semiconductor device will also be simply referred to as a "lead frame."

[0016] [Lead frame configuration] First, the configuration of a lead frame according to this embodiment will be described. FIG. 1 is a perspective view of a lead frame 100 according to this embodiment. FIG. 2 is a plan view of the lead frame 100 according to this embodiment. FIG. 2 is a view of the lead frame 100 as viewed from above. FIG. 3 is a partially enlarged view of FIG. 2. In FIG. 3, region III in FIG. 2 is enlarged. FIG. 4 is a partially enlarged view of FIG. 3. In FIG. 4, region IV in FIG. 3 is enlarged. FIG. 5 is another partially enlarged view of FIG. 2. In FIG. 5, region V in FIG. 2 is enlarged. FIG. 6 is a partially enlarged view of FIG. 5. In FIG. 6, region VI in FIG. 5 is enlarged. FIGS. 7A and 7B are perspective views of a metal frame 10 according to this embodiment. FIG. 7A is a perspective view of the metal frame 10 as viewed from the top, and FIG. 7B is a perspective view of the metal frame 10 as viewed from the bottom. FIG. 8 is a cross-sectional view of the lead frame 100 according to this embodiment. FIG. 8 shows a cross-section of the lead frame 100 taken along line VIII-VIII in FIG. 2. Fig. 9 is a partially enlarged view of Fig. 8. In Fig. 9, region IX in Fig. 8 is enlarged.

[0017] 2 and 8, and Fig. 10, which will be described later, detailed illustration of bonding portion 13 is omitted. Also, in Fig. 7A and 7B, and Fig. 14A, 14B, 15A, and 15B, which will be described later, patterns are applied to the areas where bonding portion 13 exists to indicate the positions of bonding portion 13. Also, in Fig. 9, and Fig. 16 to Fig. 20, which will be described later, the surface shape of roughened portion 14 is omitted and shown as a flat surface.

[0018] First, with reference to FIG. 1, an outline of the configuration of a lead frame 100 will be described.

[0019] 1, the lead frame 100 includes a metal frame 10 and a reflector resin 20. The lead frame 100 is a package for mounting an optical semiconductor element. The lead frame 100 is also called a "package component" or a "resin-coated lead frame."

[0020] The metal frame 10 has a first portion 11A and a second portion 11B. The second portion 11B is located on the same plane as the first portion 11A (the XY plane in the illustrated example) and is spaced apart from the first portion 11A. The first portion 11A and the second portion 11B are flat portions extending in the same plane. In the example shown in FIG. 1, the first portion 11A and the second portion 11B are aligned along the Y-axis direction. The first portion 11A and the second portion 11B have the same configuration except for, for example, their external shapes. In the example shown in FIG. 1, the first portion 11A is larger than the second portion 11B. The first portion 11A and the second portion 11B may have the same external shape.

[0021] The reflector resin 20 has a fixing portion 21 and an outer periphery portion 25. In Fig. 1, the portion below the dashed line on the reflector resin 20 is the fixing portion 21, and the portion above the dashed line is the outer periphery portion 25.

[0022] The fixing portion 21 is a portion of the reflector resin 20 located on the same plane as the metal frame 10 (the XY plane in the illustrated example). The fixing portion 21 includes a joining portion 22 and a peripheral portion 23 formed integrally with the joining portion 22. The joining portion 22 is located between the first portion 11A and the second portion 11B and contacts the first portion 11A and the second portion 11B to join the first portion 11A and the second portion 11B. The joining portion 22 does not contact the upper surfaces of the first portion 11A and the second portion 11B (the element mounting portion 12 described below). The peripheral portion 23 is arranged along the outer periphery of the metal frame 10 in a plan view of the metal frame 10 and contacts the first portion 11A and the second portion 11B in a portion other than between the first portion 11A and the second portion 11B.

[0023] The outer surrounding portion 25 is a portion of the reflector resin 20 located above the metal frame 10. The outer surrounding portion 25 is a frame-shaped portion located above the fixed portion 21 and standing upward from the fixed portion 21. The outer surrounding portion 25 has an opening 26 that exposes the first portion 11A and the second portion 11B. That is, the outer surrounding portion 25 is open so as to expose the first portion 11A and the second portion 11B. The opening 26 also exposes the coupling portion 22.

[0024] The reflector resin 20 is a molded resin formed using a mold or the like, and the fixing portion 21 and the surrounding portion 25 are integrally formed. In the illustrated example, the inner wall of the surrounding portion 25 surrounding the opening 26 is inclined so that the upper side of the opening 26 is wider (see FIG. 8 for details).

[0025] The reflector resin 20 includes, for example, a base resin and a white pigment. The white pigment of the reflector resin 20 may be, for example, titanium oxide (TiO2). Other white pigments than titanium oxide may be used for the white pigment of the reflector resin 20, such as zinc oxide (ZnO), barium sulfate (BaSO4), silicon oxide (SiO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), and aluminum nitride (AlN). The base resin of the reflector resin 20 may be, for example, a thermosetting resin. Examples of the thermosetting resin of the reflector resin 20 include epoxy resin, silicone resin, polyimide resin, UP (unsaturated polyester), and acrylic resin.

[0026] Next, the detailed configuration of the metal frame 10 will be described with reference to FIGS.

[0027] As shown in FIG. 2, the first region 11A of the metal frame 10 includes a first element mounting portion 12A and a first bonding portion 13A. The second region 11B of the metal frame 10 includes a second element mounting portion 12B and a second bonding portion 13B. As shown in FIGS. 3 and 4, the first bonding portion 13A includes a first roughened portion 14A and a first coating 15A. The first coating 15A includes a first organic molecule 16A that includes a first metal bonding group 17A, a first resin bonding group 18A, and a first main skeleton 19A. As shown in FIGS. 5 and 6, the second bonding portion 13B includes a second roughened portion 14B and a second coating 15B. Second coating 15B includes second organic molecules 16B that include second metal bonding groups 17B, second resin bonding groups 18B, and second main backbone 19B.

[0028] The first element mounting portion 12A and the first bonding portion 13A of the first portion 11A and the second element mounting portion 12B and the second bonding portion 13B of the second portion 11B have, for example, substantially the same configuration. The following describes an example in which the first element mounting portion 12A and the first bonding portion 13A and the second element mounting portion 12B and the second bonding portion 13B have substantially the same configuration. Note that the first element mounting portion 12A and the first bonding portion 13A and the second element mounting portion 12B and the second bonding portion 13B may have different configurations in some parts.

[0029] Hereinafter, when providing a common explanation for the first portion 11A and the second portion 11B, the first element mounting portion 12A and the second element mounting portion 12B may be collectively referred to as element mounting portion 12, and the first bonding portion 13A and the second bonding portion 13B may be collectively referred to as bonding portion 13. Similarly, when providing a common explanation for the first region 11A and the second region 11B, the first roughened portion 14A and the second roughened portion 14B, the first coating 15A and the second coating 15B, the first organic molecule 16A and the second organic molecule 16B, the first metal bonding group 17A and the second metal bonding group 17B, the first resin bonding group 18A and the second resin bonding group 18B, and the first main backbone 19A and the second main backbone 19B may be collectively referred to as the roughened portion 14, the coating 15, the organic molecule 16, the metal bonding group 17, the resin bonding group 18, and the main backbone 19, respectively.

[0030] As shown in FIGS. 2 and 8 , the element mounting portion 12 is an area for mounting an optical semiconductor element and electrically connecting the optical semiconductor element to the metal frame 10, and is exposed to an opening 26 provided in the outer casing 25. That is, the optical semiconductor element mounted on the lead frame 100 is surrounded by the outer casing 25 and is connected to the metal frame 10 at the element mounting portion 12 within the opening 26 of the outer casing 25. Therefore, when light is irradiated from the optical semiconductor element, the light can be efficiently reflected by the outer casing 25 and emitted from the optical semiconductor device. In the example shown in FIGS. 2 and 8 , the first element mounting portion 12A is a portion of the upper surface of the first portion 11A other than the first bonding portion 13A, surrounded by the outer casing 25 and exposed to the opening 26. The second element mounting portion 12B is a portion of the upper surface of the second portion 11B other than the second bonding portion 13B, surrounded by the outer casing 25 and exposed to the opening 26.

[0031] The element mounting portion 12 is made of metal. As will be described in detail later, the element mounting portion 12 is made of, for example, a bright plate. The surface roughness of the element mounting portion 12 is smaller than that of the roughened portion 14. The developed area ratio (Sdr) of the element mounting portion 12 is, for example, 0.05 or less, and may be 0.005 or less. Sdr is one of the indexes of surface roughness specified in ISO 25178 and represents the increase in the developed area (surface area) of a defined region relative to the area (planar area) of the defined region. The Sdr of a completely flat surface is 0. The surface roughness of the element mounting portion 12 can be adjusted, for example, by the manufacturing conditions of the bright plating. Examples of bright plating include high-brightness plating and ultra-high-brightness plating. The glossiness of high-brightness plating is, for example, 1.0 to 1.4. The glossiness of ultra-high-brightness plating is, for example, 1.5 to 2.3, and may be 1.9 to 2.3. The gloss level is a measurement value measured using a micro-surface colorimeter / reflectometer. An example of a micro-surface colorimeter / reflectometer is the VSR400 manufactured by Nippon Denshoku Industries Co., Ltd.

[0032] The joint portion 13 is at least a part of the portion of the metal frame 10 that contacts the fixed portion 21. The first joint portion 13A is located at the interface between the first portion 11A and the fixed portion 21. The second joint portion 13B is located at the interface between the second portion 11B and the fixed portion 21. In the illustrated example, the first joint portion 13A and the second joint portion 13B each contact the coupling portion 22.

[0033] As shown in FIGS. 7A, 7B, and 8, the first bonding portion 13A is disposed on the side surface of the first portion 11A. The second bonding portion 13B is disposed on the side surface of the second portion 11B. In the example shown in FIGS. 7A and 7B, the first bonding portion 13A is disposed only on the side surface of the first portion 11A at the end of the first portion 11A that faces the second portion 11B. In the example shown in FIGS. 7A and 7B, the second bonding portion 13B is disposed only on the side surface of the second portion 11B at the end of the second portion 11B that faces the first portion 11A.

[0034] The bonding portion 13 has a stepped shape. This increases the contact area between the bonding portion 13 and the fixed portion 21, making the bonding portion 13 and the fixed portion 21 less likely to separate. Furthermore, even when pressure is applied to the lead frame 100 in the vertical direction, the stepped shape resists the pressure, making the bonding portion 13 and the fixed portion 21 less likely to separate. In the illustrated example, the stepped shape of the bonding portion 13 is formed so that the step is lowered on the lower surface side of the metal frame 10. Furthermore, the stepped shape of the bonding portion 13 is a vertical step. The stepped shape of the bonding portion 13 is not particularly limited. For example, the stepped shape of the bonding portion 13 may be formed so that the step is lowered on the upper surface side of the metal frame 10, or may be formed so that the step is lowered on both the upper and lower surfaces. Furthermore, the stepped shape of the bonding portion 13 may be a curved step.

[0035] The roughened portion 14 of the joint 13 is made of metal. The roughened portion 14 is a part of the outermost surface of the metal portion of the metal frame 10. As will be described in detail later, the roughened portion 14 is formed by roughening plating, such as roughened silver plating or roughened copper plating. The roughened portion 14 may also be formed by roughening metal. Note that, although the roughened state of the roughened portion 14 is depicted in FIG. 3 and other figures as a linear zigzag, the roughened portion 14 may also have curved irregularities. Furthermore, the roughened portion 14 may have irregular irregularities rather than regular irregularities.

[0036] Roughened portion 14 has a surface roughness greater than the surface roughness of element mounting portion 12. This increases the adhesive strength between fixing portion 21 and bonding portion 13 due to the anchor effect. Sdr of roughened portion 14 is, for example, 0.5 or more, and may be 2 or more, 5 or more, or 8 or more. Sdr of roughened portion 14 may be 20 or less, or 15 or less. The surface roughness of roughened portion 14 can be adjusted, for example, by the manufacturing conditions of the roughening plating or the conditions of the roughening process.

[0037] The coating 15 of the bonding portion 13 is formed on the surface of the roughened portion 14. The coating 15 is formed on the entire surface of the roughened portion 14. The coating 15 is, for example, a monomolecular film containing organic molecules 16 in which molecular chains are aligned in the same direction. The thickness of the coating 15 is, for example, around 1 nm, and the thickness of the coating 15 is exaggerated in Figures 3 to 6 for clarity.

[0038] The organic molecules 16 of the coating 15 include metal bonding groups 17 that chemically bond to the roughened portion 14, resin bonding groups 18 that chemically bond to the fixing portion 21 (specifically, the bonding portion 22 in the illustrated example), and a main skeleton 19 located between the metal bonding groups 17 and the resin bonding groups 18. In FIGS. 4 and 6, the metal bonding groups 17, the resin bonding groups 18, and the main skeleton 19 are schematically shown as a circle, a triangle, and a square, respectively. The metal bonding group 17 is covalently bonded to one end of the main skeleton 19, and the resin bonding group 18 is covalently bonded to the other end of the main skeleton 19. The organic molecules 16 are synthesized using various organic synthesis techniques. The organic molecules 16 do not necessarily need to include the main skeleton 19; the metal bonding groups 17 and the resin bonding groups 18 may be directly covalently bonded to each other.

[0039] The metal bonding groups 17 have the property of chemically bonding to metals. As a result, in the coating 15, the molecular chains of the organic molecules 16 are arranged in the same direction on the surface of the roughened portion 14, forming a monomolecular film of the organic molecules 16. In other words, the coating 15 is a monomolecular film formed by self-assembly of the metal bonding groups 17 chemically bonding to the surface of the roughened portion 14. The monomolecular film has high heat resistance, which prevents deterioration of the coating 15 during use of the lead frame 100.

[0040] The metal bonding group 17 includes a functional group that exhibits chemical bonding with a metal. The chemical bond between the metal bonding group 17 and the metal is, for example, a hydrogen bond or a coordinate bond. The metal bonding group 17 may chemically bond with an oxide of the metal that constitutes the roughened portion 14. The metal bonding group 17 includes, for example, a functional group that includes an atom with an unshared electron pair capable of forming a coordinate bond, or a functional group such as a hydroxyl group or a carbonyl group that is capable of forming a hydrogen bond.

[0041] The chemical structure of metal bonding group 17 is selected, for example, depending on the type of metal constituting roughened portion 14. For example, when the metal constituting roughened portion 14 is silver, metal bonding group 17 includes a functional group containing a sulfur atom with an oxidation number of −2. Furthermore, the sulfur atom has an unshared electron pair capable of forming a coordinate bond with the metal. This results in a strong chemical bond between the silver in roughened portion 14 and metal bonding group 17. Although silver can recrystallize due to heat, the chemical bond with metal bonding group 17 fixes the silver in roughened portion 14, preventing recrystallization and suppressing a decrease in the surface roughness of roughened portion 14. This suppresses a decrease in the anchoring effect of roughened portion 14. Examples of functional groups containing a sulfur atom with an oxidation number of −2 include thiol and thioketone.

[0042] Furthermore, for example, when the metal constituting roughened portion 14 is copper, metal bonding group 17 includes a functional group containing a nitrogen atom with an oxidation number of -3. This results in a strong chemical bond between the copper of roughened portion 14 and metal bonding group 17. Therefore, as described above, the copper of roughened portion 14 is immobilized by the chemical bond with metal bonding group 17, preventing recrystallization and suppressing a decrease in the surface roughness of roughened portion 14. This suppresses a decrease in the anchoring effect of roughened portion 14. Examples of functional groups containing a nitrogen atom with an oxidation number of -3 include primary amines and secondary amines. The secondary amine may be a secondary amine contained in a nitrogen-containing heterocycle. Examples of the nitrogen-containing heterocycle include an imidazole skeleton, a benzimidazole skeleton, a triazole skeleton, a tetrazole skeleton, a thiazole skeleton, a benzothiazole skeleton, a thiadiazole skeleton, an oxazole skeleton, a benzoxazole skeleton, an oxadiazole skeleton, a pyridine skeleton, a pyrimidine skeleton, a pyrazine skeleton, a pyridazine skeleton, a triazine skeleton, and a purine skeleton. Metal binding group 17 may have a structure in which some carbon atoms in the skeleton of these nitrogen-containing heterocycles are replaced with thiol or thioketone.

[0043] The resin bonding group 18 includes a functional group that exhibits chemical bonding with the resin. During the curing reaction of the reflector resin 20, the resin bonding group 18 forms a chemical bond by reacting with the base resin of the reflector resin 20. The chemical bond between the resin bonding group 18 and the resin is, for example, a covalent bond. Examples of functional groups contained in the metal bonding group 17 include hydroxyl groups, carboxylic acids, acid anhydrides, primary amines, secondary amines, tertiary amines, amide groups, vinyl groups, alkoxysilyl groups, and silanol groups. The resin bonding group 18 also acts to improve the wetting tension of the roughened portion 14 with respect to the resin. Therefore, when molding the reflector resin 20, the reflector resin 20 can easily penetrate into the recesses of the roughened portion 14 due to capillary action, thereby preventing the recesses of the roughened portion 14, which have a large surface roughness, from being left unfilled with resin.

[0044] The chemical structure of the resin bonding group 18 is selected depending on, for example, the type of base resin contained in the reflector resin 20. For example, when the reflector resin 20 contains an epoxy resin as the base resin, the resin bonding group 18 contains a functional group containing a nitrogen atom with an oxidation number of -3. This allows the nitrogen atom to form a C-N bond with the carbon of the epoxy group during a ring-opening reaction of the epoxy group, facilitating the formation of a chemical bond between the epoxy group of the epoxy resin and the resin bonding group 18. Examples of functional groups containing a nitrogen atom with an oxidation number of -3 include primary amines and secondary amines. The secondary amine may be a secondary amine contained in a nitrogen-containing heterocycle, as in the example of the metal bonding group 17 described above.

[0045] In this specification, the examples of functional groups contained in the resin binding group 18 refer to the state before chemical bonding with the resin, and the functional group may change upon chemical bonding with the resin. For example, if the resin binding group 18 contains a primary amine or a secondary amine as a functional group, the primary amine or secondary amine changes to a secondary amine or a tertiary amine through a reaction that forms a chemical bond with the resin. Specifically, the primary amine or secondary amine becomes a secondary amine or a tertiary amine by reacting with a carbon atom through a ring-opening reaction of the epoxy group during curing of the epoxy resin. Even in such cases, the resin binding group 18 is expressed as containing a primary amine or a secondary amine. In other words, in this specification, unless otherwise specified, the functional group contained in the resin binding group 18 refers to the functional group before chemical bonding with the fixing portion 21. The same is true for metal bonding group 17; even if the functional group of metal bonding group 17 changes due to chemical bonding with roughened portion 14, unless otherwise specified in this specification, the functional group contained in metal bonding group 17 refers to the functional group before chemical bonding with roughened portion 14.

[0046] Furthermore, metal bonding group 17 and resin bonding group 18 may each contain multiple functional groups. For example, metal bonding group 17 and resin bonding group 18 may each contain a functional group containing a sulfur atom with an oxidation number of −2 and a functional group containing a nitrogen atom with an oxidation number of −3.

[0047] The main skeleton 19 includes, for example, one or more selected from the group consisting of a methylene chain, a siloxane chain, a glycol chain, an aryl skeleton, an acene skeleton, and derivatives thereof. When the organic molecules 16 have the main skeleton 19, the interaction of the main skeletons 19 makes it easier to form a coating 15 in which the organic molecules 16 are arranged at a high density.

[0048] Next, the detailed cross-sectional structure of the metal frame 10 will be described with reference to Fig. 9. Fig. 9 shows the cross-sectional structure of the first portion 11A of the metal frame 10, but the second portion 11B may also have a cross-sectional structure similar to that of the first portion 11A. In other words, in the following description of the cross-sectional structure, the first portion 11A may be read as the second portion 11B.

[0049] As shown in FIG. 9, the first portion 11A has a base material 30, a first plating layer 31, and a second plating layer 32.

[0050] The substrate 30 constitutes the metal substrate of the first portion 11A. The substrate 30 is, for example, copper or a copper alloy. When a copper alloy substrate is used as the substrate 30, the surface may be plated with pure copper, such as copper strike plating or copper plating. Alternatively, the substrate 30 may be made of iron, an iron-nickel alloy, stainless steel, or aluminum.

[0051] The first plating layer 31 is laminated on the surface of the base material 30. For example, the first plating layer 31 covers the entire surface of the base material 30. Note that when the shape of the first portion 11A is defined by cutting the base material 30 after the formation of the first plating layer 31, the first plating layer 31 is not laminated on the cut surface.

[0052] The first plating layer 31 is, for example, silver strike plating. The first plating layer 31 may also have a layered structure of multiple plating layers. For example, the first plating layer 31 may have a layered structure of nickel plating, palladium plating, and silver plating in this order from the base material 30 side, or a layered structure of nickel plating, palladium plating, and gold plating in this order. The presence of nickel plating and palladium plating on the base material 30 side can suppress diffusion of metals of the base material 30, such as copper, into the surface of the metal frame 10.

[0053] The second plating layer 32 is laminated on the surface of the first plating layer 31 opposite to the substrate 30 side. For example, the second plating layer 32 covers the entire surface of the first plating layer 31 opposite to the substrate 30 side. Note that the second plating layer 32 may not cover a portion of the surface of the first plating layer 31 as long as it covers the surface of the first plating layer 31 on the upper surface side in the first portion 11A.

[0054] The second plating layer 32 is, for example, bright silver plating. Ultra-high-brightness silver plating may be used as the bright silver plating for the second plating layer 32. The element mounting portion 12 is a part of the second plating layer 32 (specifically, a portion of the second plating layer 32 exposed in the opening 26). This can improve the brightness of an optical semiconductor device using the lead frame 100.

[0055] Furthermore, roughened portion 14 is formed on the surface of a portion of second plating layer 32 that is located on the side surface of first portion 11A. In the example shown in Fig. 10, roughened portion 14 is formed over the entire vertical area of ​​the side surface of first portion 11A. In the case of the cross-sectional structure shown in Fig. 10, roughened portion 14 is, for example, a roughened silver plating.

[0056] [Configuration of optical semiconductor device] Next, the configuration of an optical semiconductor device equipped with lead frame 100 according to this embodiment will be described. Fig. 10 is a cross-sectional view of optical semiconductor device 101 according to this embodiment. Fig. 10 shows a cross section of optical semiconductor device 101 at a position corresponding to Fig. 8.

[0057] As shown in FIG. 10, an optical semiconductor device 101 includes a lead frame 100, an optical semiconductor element 50, wires 51, and a sealing resin 52.

[0058] The optical semiconductor element 50 is placed on the element mounting portion 12 of the lead frame 100. In the example shown in FIG. 10, the optical semiconductor element 50 is placed on the first element mounting portion 12A of the first portion 11A. The first element mounting portion 12A and the second element mounting portion 12B are regions on which the optical semiconductor element 50 can be placed, and as long as the optical semiconductor element 50 is placed on one of the first element mounting portion 12A and the second element mounting portion 12B, the optical semiconductor element 50 does not need to be placed on the other. In the example shown in FIG. 10, the optical semiconductor element 50 is joined to the element mounting portion 12 by die bonding.

[0059] The optical semiconductor element 50 is, for example, a light-emitting element such as an LED (Light Emitting Diode) or a laser element. The light emitted by the light-emitting element is not limited to visible light. That is, the light-emitting element may emit invisible light such as ultraviolet light or infrared light. The optical semiconductor element 50 may also be an optical semiconductor element other than a light-emitting element, such as a light-receiving element. The optical semiconductor device 101 may also include a plurality of optical semiconductor elements 50. When there are a plurality of optical semiconductor elements 50, the same type of optical semiconductor elements may be used as the multiple optical semiconductor elements 50, or different types of optical semiconductor elements may be used. For example, the multiple optical semiconductor elements 50 may include a light-emitting element and a light-receiving element.

[0060] The wires 51 electrically connect the optical semiconductor element 50 to the first portion 11A and the second portion 11B of the metal frame 10. Therefore, in the example shown in Fig. 10, the optical semiconductor element 50 is mounted on the lead frame 100 by wire bonding. There are no particular limitations on the method by which the optical semiconductor element 50 is mounted on the lead frame 100. The optical semiconductor element 50 may be mounted on the lead frame 100 by, for example, flip-chip mounting.

[0061] The sealing resin 52 seals the optical semiconductor element 50 on the metal frame 10. The sealing resin 52 fills the opening 26 provided in the outer casing 25. The sealing resin 52 is, for example, a resin for sealing semiconductor elements, such as a silicone resin.

[0062] [Lead frame manufacturing method] Next, a method for manufacturing the lead frame 100 according to this embodiment will be described below. Fig. 11 is a flowchart showing an example of a method for manufacturing the lead frame 100 according to this embodiment.

[0063] 11, first, a first plating layer 31 is formed on the surface of the base material 30 (step S11). The first plating layer 31 can be formed by a known plating method such as strike plating. In step S11, plating may be applied to an individual base material 30 having a shape corresponding to one lead frame 100, or plating (e.g., hoop plating) may be applied to a continuous base material 30 (e.g., a hoop-shaped base material) that can be used for multiple lead frames 100.

[0064] Next, the second plating layer 32 is formed on the surface of the first plating layer 31 opposite the substrate 30 (step S12). The second plating layer 32 is formed, for example, by electrolytic plating. For example, the second plating layer 32 is formed by controlling the plating solution composition, concentration, flow rate, current waveform, and current value during electrolytic plating to perform gloss plating. For example, a plating solution containing an inorganic or organic brightener added to an aqueous solution of a metal salt such as silver salt is used. By controlling the temperature and flow rate of the plating solution and the current density during the plating process, the brightener is adsorbed to the convex portions of the uneven plating surface, suppressing plating growth in the convex portions while promoting plating growth in the concave portions. This flattens the surface of the second plating layer 32 and reduces its surface roughness. Prior to forming the second plating layer 32, a masking process may be performed to define areas on the surface of the first plating layer 31 where the second plating layer 32 will not be formed.

[0065] Next, a masking process is performed on the portions of the surface of the second plating layer 32 where the roughened portion 14 will not be formed (step S13). For example, at least the portions of the surface of the second plating layer 32 that are exposed in the openings 26 are masked. Furthermore, when a hoop-shaped base material in which multiple base materials 30 are continuously arranged in a matrix is ​​used, for example, the mask is applied in a stripe pattern so that the area between the first portion 11A and the second portion 11B is exposed. This allows efficient formation of the joints 13 at the portions where the first portion 11A and the second portion 11B face each other, even when a large number of lead frames 100 are manufactured at once.

[0066] Next, the roughened portion 14 is formed (step S14). For example, the roughened portion 14 is formed by performing roughening plating on the portions not masked in step S13 by controlling the plating solution composition, concentration, flow rate, current waveform, and current value during electroplating. For example, a plating solution containing an inorganic or organic roughening additive added to an aqueous solution of a metal salt such as a silver salt is used. By controlling the temperature and flow rate of the plating solution and the current density of the plating process, a brightener is adsorbed into the recesses of the unevenness of the plated surface, suppressing plating growth in the recesses while promoting plating growth in the protrusions. Alternatively, for example, PR (periodic reverse) pulse plating or the like can be used to alternately repeat plating growth and plating dissolution, thereby preferentially growing the protrusions of the unevenness of the plated surface. This can increase the surface roughness of the roughened portion 14. Furthermore, using these methods, the surface roughness of the roughened portion 14 can be increased by increasing the thickness of the roughened portion 14. The shape of the unevenness of the roughened portion 14 can be, for example, spherical or acicular, but is not particularly limited. From the viewpoint of preventing physical or thermal changes in shape of roughened portion 14 and reducing the anchoring effect, the asperities of roughened portion 14 are preferably spherical. After roughened portion 14 is formed, the mask is removed. The mask may be removed after coating 15 is formed.

[0067] Next, the coating 15 is formed (Step S15). To form the coating 15, first, the organic molecules 16 are dispersed in a solvent to prepare a dispersion. The solvent can be at least one of an organic solvent and water. When using water as the solvent, an anionic, cationic, or nonionic surfactant may be added as needed to improve the dispersibility of the organic molecules 16. Furthermore, a pH buffer and an antioxidant may be added to stabilize the organic molecules 16. The substrate 30, on which the roughened portion 14 has been formed, is then immersed in the dispersion. As a result, each of the organic molecules 16 chemically bonds its metal bonding group 17 to the roughened portion 14, while its main backbone 19 and resin bonding group 18 are aligned in the same order, stabilizing them and forming a self-assembled monolayer. Based on the above principles, a self-assembled monolayer is formed as the coating 15, and the substrate 30 is then lifted out of the dispersion. After lifting, the substrate is washed to remove excess organic molecules 16.

[0068] Next, the reflector resin 20 is molded (step S16). For example, a thermosetting resin is filled into a mold for forming the shape of the outer periphery 25, and a curing process is performed to form the reflector resin 20, thereby obtaining the lead frame 100. At this time, the thermosetting resin is also disposed between the first portion 11A and the second portion 11B and on the outer periphery of the first portion 11A and the second portion 11B, so that the fixing portion 21 is also formed. After molding the reflector resin 20, a deburring process such as alkaline electrolysis is performed. The deburring process removes the coating 15 formed on areas other than the surface of the roughened portion 14.

[0069] The lead frame 100 is completed through the above steps. Furthermore, an optical semiconductor element 50 is mounted on the lead frame 100 and sealed with sealing resin 52 to obtain an optical semiconductor device 101. If a hoop-shaped base material is used, the lead frame 100 is singulated after the formation of the reflector resin 20 or after sealing with sealing resin 52.

[0070] [Effects, etc.] Next, the effects of the lead frame 100 according to this embodiment will be described.

[0071] First, the results of an experiment conducted to confirm the effect of improving the reliability of the lead frame 100 according to this embodiment will be described.

[0072] (1) Leakage evaluation Samples of the lead frame 100 according to the embodiment and samples of the lead frame according to the comparative example were actually fabricated, and the fabricated samples were subjected to a leakage evaluation.

[0073] <Preparation of Samples in Examples 1 to 3> The samples of Examples 1 to 3 were prepared by changing the surface roughness of the roughened portion 14 of the lead frame 100 described above. The samples of Examples 1 to 3 were prepared in the same manner except for the surface roughness of the roughened portion 14. The specific materials used were as follows:

[0074] Base material 30: Copper alloy First plating layer 31: silver strike plating Second plating layer 32: Bright silver plating (ultra-high brightness silver plating, Sdr=0.003) Roughened part 14: roughened silver plating Metal binding group 17, resin binding group 18: Nitrogen-containing heterocycle containing two thioketones and one secondary amine in the ring Reflector Resin 20: White epoxy resin containing triglycidyl isocyanurate, acid anhydride, and titanium dioxide

[0075] Furthermore, the Sdr of the roughened portion 14 of the sample of Example 1 was 0.8, the Sdr of the bonded portion 13 of the sample of Example 2 was 2.4, and the Sdr of the sample of Example 3 was 8.1.

[0076] <Preparation of Sample of Comparative Example 1> The sample of Comparative Example 1 was produced in the same manner as the samples of Examples 1 to 3, except that the roughened portion 14 and the coating 15 were not formed.

[0077] <Preparation of Sample of Comparative Example 2> A sample of Comparative Example 2 was produced in the same manner as the samples of Examples 1 to 3, except that the roughened portion 14 was not formed.

[0078] <Preparation of Sample of Comparative Example 3> A sample of Comparative Example 3 was prepared in the same manner as in Example 1, except that the coating 15 was not formed.

[0079] <Preparation of Sample of Comparative Example 4> A sample of Comparative Example 4 was prepared in the same manner as in Example 2, except that the coating 15 was not formed.

[0080] <Leak evaluation results> To evaluate leakage of the samples of the example and comparative examples, the samples were heated at 150°C for 2 hours, and then oil-based red ink was applied to the underside of the sample, and the sample was visually inspected to see if any ink had leaked to the top surface. 680 samples were prepared and the incidence of ink leakage was evaluated. The evaluation results are shown in Table 1. In Table 1, since the roughened portion 14 was not formed in Comparative Examples 1 and 2, the surface roughness (Sdr) is the surface roughness of the bright silver plating.

[0081] [Table 1]

[0082] As shown in Table 1, in Comparative Example 1, in which neither roughened portion 14 nor coating 15 was formed, the incidence of ink leakage was 89%, which was very high. Furthermore, in Comparative Examples 2 to 4, the incidence of ink leakage was reduced by forming either roughened portion 14 or coating 15, but was still 5% or more.

[0083] In contrast, in the samples of the lead frame 100 according to this embodiment, such as in Examples 1 to 3, almost no ink leakage occurred, and no ink leakage occurred when the Sdr of the joint 13 was 2.4 or higher.

[0084] Furthermore, in Comparative Examples 3 and 4, the ink leakage rate increases as the surface roughness of the joint increases, whereas in Examples 1 and 2, the ink leakage rate decreases as the surface roughness of joint 13 increases. In other words, if coating 15 is not formed, forming roughened portion 14 does not provide a certain level of leakage suppression effect, but by forming coating 15, the leakage suppression effect achieved by forming roughened portion 14 can be further enhanced.

[0085] As described above, it can be seen that the formation of the roughened portion 14 and the coating 15 significantly reduces the incidence of ink leakage, and improves the reliability of the lead frame 100.

[0086] (2) Adhesive strength measurement Next, a test sample of the metal frame for measuring adhesive strength was prepared, and the adhesive strength between the test sample and the reflector resin was measured.

[0087] <Test sample> As a test sample of the metal frame, a copper-based metal plate having the following surface configuration was prepared.

[0088] Test sample 1: Copper substrate as is Test sample 2: Bright silver plating Test sample 3: Roughened silver plating (roughened part 14) Test sample 4: Bright silver plating + coating 15 (same as Examples 1 to 3 above) Test sample 5: Roughened silver plating (roughened portion 14) + coating 15 (same as in Examples 1 to 3 above)

[0089] The surface configuration of the test sample 5 corresponds to the configuration of the bonding portion 13 of the lead frame 100 according to this embodiment.

[0090] <Adhesion strength measurement> Fig. 12 is a side view illustrating a method for measuring adhesive strength. As shown in Fig. 12, a truncated cone-shaped epoxy resin R (the same as the reflector resin 20 in Examples 1 to 3) was hardened and molded on the surface of a test sample S (the above test samples 1 to 5), and a stress at which shear failure occurred when a force was applied in the direction indicated by the arrow (a direction parallel to the surface of the test sample S) was measured as adhesive strength. The contact area between the test sample S and the epoxy resin R was 10 mm 2 A universal bond tester (ESR-4000, manufactured by Nordson DAGE) was used for the measurements.

[0091] Fig. 13 shows the results of measuring adhesive strength, where the average adhesive strength of each test sample is indicated by a marker, and the range of variation in adhesive strength is indicated by an error bar.

[0092] As shown in Figure 13, although the surface roughness of the surface that comes into contact with the epoxy resin changes between test samples 1 and 3, there is almost no difference in adhesive strength, and simply changing the surface roughness of the surface does not have the effect of improving adhesion to the epoxy resin. Furthermore, for test sample 3, the range of the error bar indicating the range of variation in adhesive strength has widened, which suggests that increasing the surface roughness of the surface is having an adverse effect.

[0093] In contrast, test sample 4 and test sample 5, on which coating 15 was formed, had improved adhesive strength compared to when coating 15 was not formed. In particular, when coating 15 was formed, the effect of improving adhesive strength by increasing the surface roughness was realized, which was not realized when coating 15 was not formed. In other words, compared to when roughened portion 14 or coating 15 was formed alone, the formation of both roughened portion 14 and coating 15 can be said to produce a synergistic effect rather than a simple additive effect.

[0094] (3) Summary As described above, in the lead frame 100 according to the present embodiment, the bonding portion 13, which includes the roughened portion 14 and the coating 15 formed on the surface of the roughened portion 14, is provided at the interface between the first portion 11A and the second portion 11B of the metal frame 10 and the fixing portion 21 of the reflector resin 20. This improves the adhesion between the metal frame 10 and the fixing portion 21 of the reflector resin 20, thereby improving the reliability of the lead frame 100. For example, in the lead frame 100, the metal frame 10 and the reflector resin 20 are less likely to peel off from each other. Furthermore, when the lead frame 100 is used in an optical semiconductor device 101, for example, the sealing resin 52 is less likely to leak at the interface between the metal frame 10 and the reflector resin 20, thereby suppressing an increase in luminance variation of the optical semiconductor device 101 and contamination of pads during mounting of the optical semiconductor device 101. This is believed to be due to the following effects.

[0095] Because the surface roughness of the roughened portion 14 of the bonding portion 13 is greater than the surface roughness of the element mounting portion 12, it is believed that the anchor effect between the bonding portion 13 and the fixing portion 21 of the reflector resin 20 is greater, thereby improving the adhesion between the bonding portion 13 and the fixing portion 21. However, as shown in the above-mentioned adhesive strength measurement results, there are cases in which the formation of the roughened portion 14 alone does not sufficiently improve the adhesion to the fixing portion 21 or does not achieve the desired effect. This is believed to be because the wettability of the resin in the roughened portion 14 is insufficient, preventing the resin from penetrating into the fine details of the irregularities in the roughened portion 14 and thus preventing a sufficient contact area between the fixing portion 21 and the roughened portion 14. In contrast, in the lead frame 100, the coating 15 containing organic molecules 16 is formed on the surface of the roughened portion 14, improving the wettability of the resin in the bonding portion 13 and allowing the resin to penetrate into the fine details of the irregularities in the roughened portion 14. As a result, gaps are less likely to occur between bonding portion 13 and fixing portion 21, and the anchoring effect is fully exerted, thereby improving the adhesion between bonding portion 13 and fixing portion 21. Furthermore, organic molecules 16 contained in coating 15 include metal bonding groups 17 that chemically bond to roughened portion 14 and resin bonding groups 18 that chemically bond to fixing portion 21, so that roughened portion 14 and fixing portion 21 can be bonded via coating 15, further improving the adhesion between bonding portion 13 and fixing portion 21. Furthermore, chemical bonding of metal bonding groups 17 to roughened portion 14 suppresses oxidation and recrystallization of the metal in roughened portion 14, thereby improving the reliability of lead frame 100 during use.

[0096] Furthermore, in the lead frame 100 according to the present embodiment, the joint 13 is in contact with the coupling portion 22. The coupling portion 22 is located between the first portion 11A and the second portion 11B and is exposed to the opening 26, so that the metal frame 10 and the reflector resin 20 are particularly susceptible to peeling. However, the contact of the joint 13 with the coupling portion 22 suppresses peeling. Furthermore, when the lead frame 100 is used in the optical semiconductor device 101, the opening 26 is filled with the sealing resin 52. The contact of the joint 13 with the coupling portion 22 makes it difficult for the sealing resin 52 to leak from around the coupling portion 22.

[0097] [Modification of joint arrangement] Next, we will explain modified examples of the arrangement of the joints 13. In the above, the joints 13 are arranged only on the portions of the side surfaces of the first portion 11A and the second portion 11B that face each other, but this is not limiting.

[0098] 14A and 14B are perspective views of the metal frame 10 according to the present embodiment for explaining a first modified example of the arrangement of the joints 13. Figures 15A and 15B are perspective views of the metal frame 10 according to the present embodiment for explaining a second modified example of the arrangement of the joints 13. Figures 14A and 15A are perspective views of the metal frame 10 as seen from above, and Figures 14B and 15B are perspective views of the metal frame 10 as seen from below.

[0099] 14A and 14B, in the first modified example, first joint portion 13A is disposed over the entire portion of the side surface of first portion 11A that comes into contact with fixed portion 21. Also, second joint portion 13B is disposed over the entire portion of the side surface of second portion 11B that comes into contact with fixed portion 21. This allows for an even stronger bond between metal frame 10 and fixed portion 21.

[0100] 15A and 15B, in the second modified example, the first bonding portion 13A is disposed on the entire portion of the side surface of the first portion 11A that contacts the fixing portion 21, and on the portion of the top surface of the first portion 11A that contacts the outer casing 25 (the portion not exposed in the opening 26). This allows the metal frame 10 and the reflector resin 20 to be bonded even more firmly.

[0101] The arrangement of the bonding portions 13 in the first and second modified examples can be formed, for example, by changing the arrangement of the mask in the masking process in step S13 described above.

[0102] [Modification of the cross-sectional structure of the metal frame 10] Next, modified examples of the cross-sectional structure of the metal frame 10 will be described. FIG. 16 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a first modified example of the cross-sectional structure of the metal frame 10. FIG. 17 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a second modified example of the cross-sectional structure of the metal frame 10. FIG. 18 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a third modified example of the cross-sectional structure of the metal frame 10. FIG. 19 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a fourth modified example of the cross-sectional structure of the metal frame 10. FIG. 20 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a fifth modified example of the cross-sectional structure of the metal frame 10. FIG. 21 is an enlarged cross-sectional view of the lead frame 100 according to the present embodiment for describing a sixth modified example of the cross-sectional structure of the metal frame 10. FIGS. 16 to 21 show a cross section of the lead frame 100 at the same position as in FIG. 9.

[0103] In the following description of each modified example, differences from the cross-sectional structure shown in Fig. 9 and differences between each modified example will be mainly described, and explanation of common points will be omitted or simplified. Also, as in Fig. 9, Figs. 16 to 21 show the cross-sectional structure of the first portion 11A of the metal frame 10, but the second portion 11B may also have the same cross-sectional structure as the first portion 11A. In other words, in the following description of the cross-sectional structure, the first portion 11A may be read as the second portion 11B.

[0104] 16, in the first modified example, on the lower surface side of the first portion 11A, the second plating layer 32 is not laminated on the surface of the first plating layer 31. The first plating layer 31 in the first modified example has a laminated structure of, for example, nickel plating, palladium plating, and silver plating from the base material 30 side.

[0105] As shown in FIG. 17 , in the second modified example, first portion 11A does not have second plating layer 32, and roughened portion 14 is formed on the surface of a portion of first plating layer 31 located on the side surface of first portion 11A. Furthermore, in the second modified example, roughened portion 14 is not formed near the upper and lower surfaces of first portion 11A on the side surface of first portion 11A, and roughened portion 14 and coating 15 are not exposed to opening 26. Roughened portion 14 and coating 15 are completely covered by fixing portion 21. Because roughened portion 14 is not exposed to opening 26, a decrease in the reflectance of light emitted by optical semiconductor element 50 due to metal frame 10 can be suppressed. Furthermore, because roughened portion 14 is not exposed to opening 26, corrosion of roughened portion 14 can also be suppressed.

[0106] In the second modified example, roughened portion 14 is formed, for example, by forming roughened portion 14 on the entire side surface of first portion 11A and then peeling off roughened portion 14 from the portions near the upper and lower surfaces of first portion 11A. In the second modified example, element mounting portion 12 is a portion of first plating layer 31 (specifically, the portion of first plating layer 31 exposed in opening 26). First plating layer 31 in the second modified example has, for example, a layered structure of nickel plating, palladium plating, and gold plating from the base material 30 side. Furthermore, roughened portion 14 in the second modified example is, for example, roughened copper plating.

[0107] As shown in FIG. 18 , in the third modified example, the joint 13 does not have a stepped structure. The first plating layer 31 and the second plating layer 32 are not laminated on the side surfaces of the base material 30. The roughened portion 14 is formed on the side surfaces of the base material 30 and on the end surfaces of the first plating layer 31. The second plating layer 32 is not laminated on the surface of the first plating layer 31 on the underside of the first portion 11A. The cross-sectional structure of the third modified example can be obtained, for example, by forming the first plating layer 31 and the second plating layer 32 on a flat base material 30, cutting the base material 30 into the shape of the metal frame 10 by punching or the like, and forming the joint 13 on the cut surface. The first plating layer 31 in the third modified example has, for example, a laminated structure of nickel plating, palladium plating, and silver plating from the base material 30 side.

[0108] As shown in FIG. 19 , in the fourth modification, similar to the third modification, the bonding portion 13 does not have a stepped structure. Furthermore, the roughened portion 14 is formed on the side surface of the base material 30, the end surface of the first plating layer 31, and the end surface of the second plating layer 32. Similarly to the second modification, in the fourth modification, the first portion 11A does not have the second plating layer 32. Similarly to the second modification, in the fourth modification, the roughened portion 14 is not formed near the upper and lower surfaces of the side surface of the first portion 11A, and the roughened portion 14 and the coating 15 are not exposed in the opening 26. The first plating layer 31 in the fourth modification has, for example, a layered structure of nickel plating, palladium plating, and gold plating from the base material 30 side. Furthermore, the roughened portion 14 in the fourth modification is, for example, a roughened copper plating.

[0109] As shown in FIG. 20 , the fifth modified example has a configuration in which the formation position of the roughened portion 14 is changed from that of the third modified example. In the fifth modified example, the roughened portion 14 is formed only on the side surface of the substrate 30. The roughened portion 14 in the fourth modified example is a roughened structure formed, for example, by roughening the side surface of the substrate 30. The roughening is performed, for example, by microetching or blasting.

[0110] 21 , in the sixth modified example, the position at which roughened portion 14 is formed is changed from that of the fourth modified example, and the end portion of the upper surface of first portion 11A on the side surface side of first portion 11A is processed so that it hangs down. The hanging portion is covered from above by fixing portion 21. In the sixth modified example, roughened portion 14 and coating 15 are not exposed in opening 26. Roughened portion 14 in the sixth modified example is a roughened structure formed, for example, by roughening the side surface of substrate 30.

[0111] The cross-sectional structure of the metal frame 10 is not limited to the above example, and some of the features of the above cross-sectional structures may be combined. Furthermore, the materials and forming methods of the various parts of the metal frame 10 are not limited to the above example.

[0112] (others) While the lead frame for an optical semiconductor device according to the present disclosure has been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as they do not deviate from the gist of the present disclosure, various modifications conceivable by those skilled in the art to the present embodiments and other forms constructed by combining some of the components of the embodiments are also included within the scope of the present disclosure.

[0113] Examples of the lead frame for an optical semiconductor device according to the present disclosure, which have been described based on the above-described embodiment, are shown below. The lead frame for an optical semiconductor device according to the present disclosure is not limited to the following examples.

[0114] For example, a lead frame for an optical semiconductor device according to a first aspect of the present disclosure includes a metal frame having a first portion and a second portion located on the same plane as the first portion and spaced apart from the first portion, and a reflector resin, wherein the reflector resin has a fixing portion that is a portion of the reflector resin located on the same plane as the metal frame and in contact with the first portion and the second portion, and an outer circumferential portion that is a portion of the reflector resin located above the metal frame and molded integrally with the fixing portion, The outer casing has an opening to expose the first portion and the second portion, and the first portion has a first element mounting portion exposed at the opening and a first bonding portion located at the interface between the first portion and the fixing portion, and the first bonding portion has a surface roughness greater than the surface roughness of the first element mounting portion and includes a first roughened portion made of metal and a first coating formed on the surface of the first roughened portion and including first organic molecules, and the first organic molecules include a first metal bonding group that chemically bonds to the first roughened portion and a first resin bonding group that chemically bonds to the fixing portion.

[0115] Furthermore, for example, a lead frame for an optical semiconductor device according to a second embodiment of the present disclosure is the lead frame for an optical semiconductor device according to the first embodiment, wherein the first bonding portion has a stepped shape.

[0116] Also, for example, a lead frame for an optical semiconductor device according to a third aspect of the present disclosure is a lead frame for an optical semiconductor device according to the first or second aspect, wherein the fixing portion has a joining portion located between the first portion and the second portion, and the first joint portion contacts the joining portion.

[0117] Furthermore, for example, a lead frame for an optical semiconductor device according to a fourth aspect of the present disclosure is a lead frame for an optical semiconductor device according to any one of the first to third aspects, in which the reflector resin includes an epoxy resin and the first resin bonding group includes a nitrogen atom having an oxidation number of -3.

[0118] Furthermore, for example, a lead frame for an optical semiconductor device according to a fifth embodiment of the present disclosure is the lead frame for an optical semiconductor device according to the fourth embodiment, wherein the first resin binding group includes a primary amine or a secondary amine.

[0119] Furthermore, for example, a lead frame for an optical semiconductor device according to a sixth aspect of the present disclosure is a lead frame for an optical semiconductor device according to any one of the first to fifth aspects, in which the metal constituting the first roughened portion is silver, and the first metal bonding group contains a sulfur atom with an oxidation state of -2.

[0120] Furthermore, for example, a lead frame for an optical semiconductor device according to a seventh embodiment of the present disclosure is the lead frame for an optical semiconductor device according to the sixth embodiment, wherein the first metal bonding group includes a thiol or a thioketone.

[0121] Furthermore, for example, a lead frame for an optical semiconductor device according to an eighth aspect of the present disclosure is a lead frame for an optical semiconductor device according to any one of the first to seventh aspects, wherein the metal constituting the first roughened portion is copper, and the first metal bonding group contains a nitrogen atom with an oxidation number of -3.

[0122] Furthermore, for example, a lead frame for an optical semiconductor device according to a ninth embodiment of the present disclosure is the lead frame for an optical semiconductor device according to the eighth embodiment, wherein the first metal bonding group includes a primary amine or a secondary amine.

[0123] Furthermore, for example, a lead frame for an optical semiconductor device according to a tenth aspect of the present disclosure is a lead frame for an optical semiconductor device according to any one of the first to ninth aspects, in which the first roughened portion is not exposed to the opening.

[0124] Furthermore, for example, a lead frame for an optical semiconductor device according to an eleventh aspect of the present disclosure is a lead frame for an optical semiconductor device according to any one of the first to tenth aspects, wherein the second portion has a second element mounting portion exposed in the opening and a second bonding portion located at the interface between the second portion and the fixing portion, the second bonding portion having a surface roughness greater than that of the second element mounting portion, and includes a second roughened portion made of metal, and a second coating formed on the surface of the second roughened portion and having second organic molecules, the second organic molecules including second metal bonding groups chemically bonded to the second roughened portion and second resin bonding groups chemically bonded to the fixing portion. [Industrial Applicability]

[0125] The lead frame for an optical semiconductor device according to the present disclosure can be used in electronic components that use various optical semiconductor devices, such as light emitting devices. [Explanation of symbols]

[0126] 10 Metal Frame 11A 1st part 11B 2nd part 12 Element mounting section 12A First element mounting portion 12B second element mounting portion 13 Joint 13A 1st joint 13B 2nd joint 14 Roughening part 14A 1st roughening section 14B 2nd roughening section 15 Coating 15A 1st coating 15B 2nd coating 16 organic molecules 16A First organic molecule 16B Second organic molecule 17 Metal binding group 17A First metal binding group 17B Second metal binding group 18 Resin binding group 18A 1st resin binding group 18B 2nd resin binding group 19 Main skeleton 19A First main frame 19B Second main skeleton 20 Reflector resin 21 Fixed part 22 Joint 23 Periphery 25 Outer enclosure 26 Opening 30 Base material 31 First plating layer 32 Second plating layer 50 Optical semiconductor elements 51 Wire 52 Sealing resin 100 lead frames 101 Optical semiconductor device

Claims

1. a metal frame having a first portion and a second portion located on the same plane as the first portion and spaced apart from the first portion; a reflector resin; The reflector resin is a fixing portion of the reflector resin that is located on the same plane as the metal frame and that is in contact with the first portion and the second portion; an outer casing portion that is a portion of the reflector resin located above the metal frame and that is molded integrally with the fixing portion; the outer casing has an opening to expose the first portion and the second portion; The first portion is a first element mounting portion exposed to the opening; a first bonding portion located at an interface between the first portion and the fixing portion, The first joint portion is a first roughened portion made of metal and having a surface roughness greater than a surface roughness of the first element mounting portion; a first coating formed on a surface of the first roughened portion and including first organic molecules; The first organic molecule is a first metal bonding group that chemically bonds to the first roughened portion; a first resin binding group that chemically bonds to the immobilizing portion; Lead frames for optical semiconductor devices.

2. The first joint portion has a stepped shape. The lead frame for an optical semiconductor device according to claim 1 .

3. the fixing portion has a connecting portion located between the first portion and the second portion, The first joint portion contacts the coupling portion. The lead frame for an optical semiconductor device according to claim 1 .

4. the reflector resin includes an epoxy resin, the first resin-binding group comprises a nitrogen atom having an oxidation state of −3; The lead frame for an optical semiconductor device according to any one of claims 1 to 3.

5. the first resin-binding group comprises a primary amine or a secondary amine; The lead frame for an optical semiconductor device according to claim 4 .

6. the metal constituting the first roughened portion is silver, the first metal binding group contains a sulfur atom having an oxidation state of −2; The lead frame for an optical semiconductor device according to any one of claims 1 to 3.

7. the first metal binding group comprises a thiol or a thioketone; The lead frame for an optical semiconductor device according to claim 6 .

8. the metal constituting the first roughened portion is copper, the first metal binding group includes a nitrogen atom having an oxidation state of −3; The lead frame for an optical semiconductor device according to any one of claims 1 to 3.

9. the first metal binding group comprises a primary amine or a secondary amine; The lead frame for an optical semiconductor device according to claim 8 .

10. the first roughened portion is not exposed to the opening; The lead frame for an optical semiconductor device according to any one of claims 1 to 3.

11. The second portion is a second element mounting portion exposed to the opening; a second bonding portion located at an interface between the second portion and the fixing portion, The second joint portion is a second roughened portion made of metal and having a surface roughness greater than the surface roughness of the second element mounting portion; a second coating formed on a surface of the second roughened portion and having second organic molecules; The second organic molecule is a second metal bonding group that chemically bonds to the second roughened portion; a second resin binding group that chemically bonds to the immobilizing portion; The lead frame for an optical semiconductor device according to any one of claims 1 to 3.

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