JP6656961B2 - Lead frame for mounting optical semiconductor element and method of manufacturing the same - Google Patents

Description

  The present invention relates to a lead frame for mounting an optical semiconductor element and a method for manufacturing the same.

  2. Description of the Related Art Optical semiconductor devices equipped with LED (Light Emitting Diode) elements have come to be used in various devices such as general lighting and displays such as televisions, mobile phones, and OA devices. In these optical semiconductor devices, packages in which an LED element is mounted using a lead frame and sealed with a resin have been developed in order to meet demands for thinning, mass production, and the like.

  In general, an optical semiconductor device using a lead frame has a structure as shown in Patent Document 1. That is, the lead frame has a die pad portion on which the LED element is mounted, and a lead portion arranged at intervals around the die pad portion, and the entire or a part of the die pad portion and the lead portion is subjected to noble metal plating, and plated. It is constituted by forming a layer. Then, an LED element is mounted on the die pad section, and the LED element and the lead section are joined using a bonding wire or the like. The optical semiconductor device includes an external resin part (reflector) made of a resin that reflects light around the LED element, and a sealing resin part filled with a translucent resin around the LED element and the bonding wire. It consists of. Here, a structure in which an external resin portion (reflector) is arranged on a lead frame in which a die pad portion and a lead portion are plated with noble metal is referred to as a resin-attached lead frame.

  Optical semiconductor devices using these lead frames are generally surface-mounted packages in which the back surfaces of the lead frames are exposed. For this reason, the contact area between the die pad portion and the lead portion with the external resin portion is small, and there is a problem that the lead falls off or a part of the external resin portion peels off and the adhesiveness between the lead frame and the external resin portion. There is a demand to increase. On the other hand, Patent Literature 2 discloses an invention in which a groove having a C-shaped cross section is provided on the surface of a lead frame to improve the adhesion to an external resin portion, and particularly to enhance the peeling suppressing force in the vertical direction.

  Further, in Patent Document 1, a concave portion (thin portion) is formed inward from the edge of the back surface of the die pad portion or the lead portion, and the thin portion is covered with an external resin portion, and the adhesiveness with the external resin portion is formed. Has been improved.

JP 2004-274027 A JP 2013-58739 A

  In the optical semiconductor device described in Patent Literature 1, an LED (Light Emitting Diode) device is mounted on a part or the entire periphery of the die pad portion and the lead portion in order to enhance the adhesion between the external resin portion and the lead frame. Etching is performed from the surface opposite to the surface to form a thin portion thinner than the plate thickness inward from the edges of the die pad portion and the lead portion. If a groove is formed on the surface of the frame, the strength of the thin part will be insufficient unless the thin part formed by etching from the lower surface of the lead frame and the groove formed from the LED element mounting surface do not interfere with each other. In the method, a thin portion is removed by etching. Therefore, it is necessary to form the groove at a position inside the portion just above the thin portion so that the thin portion does not overlap with the groove.

  Further, in Patent Document 2, it is preferable that the depth of the groove processing from the lead frame surface be 1/2 of the plate thickness, and when a thin portion is formed from the back surface, it is difficult to form a groove on the thin portion. .

  Further, in the die pad portion, a die bonding paste such as an Ag paste is used to mount an optical semiconductor element. However, in order to suppress the spread of the paste, a groove may be formed in a peripheral portion of the die pad portion. . In addition, since the lower surfaces of the die pad portion and the lead portion function as external terminals, it is preferable that the lower surfaces be formed in substantially the same shape in order to make solder uniform at the time of connection. On the other hand, on the upper surface side, since an optical semiconductor element is mounted on the die pad portion and only the bonding wire is connected to the lead portion, the die pad portion is often configured to have a larger area. In such a case, since the thin portion on the die pad portion side is formed in a wide area, the groove is formed so as to overlap with the groove for suppressing the wetting spread of the die bonding paste. was difficult. In particular, it was difficult to form a groove on the die pad side of the surface where the die pad portion and the lead portion faced.

  Accordingly, an object of the present invention is to provide a lead frame for mounting an optical semiconductor element capable of forming a groove which is not affected by the arrangement of a thin portion by etching from the lower surface of the lead frame, and a method of manufacturing the same, in order to meet such a demand. I do.

In order to achieve the above object, a lead frame according to one embodiment of the present invention has a die pad portion on which an optical semiconductor element can be mounted, and a lead frame arranged opposite to the die pad portion for mounting an optical semiconductor element. A lead frame,
At least one of the die pad portion and the lead portion has a thin portion in which a part of the lower surface is thinned,
The thin portion has a thin concave portion including a region where the depression from the lower surface side is deepest, and a thin convex portion which is thicker than the thinnest portion of the thin concave portion and has a convex shape on the lower surface side,
On the upper surface side of the thin convex portion, a groove is formed ,
The lower surface of the surface of the thin protrusions, Ru flat der than the thin recess.

  According to the present invention, it is possible to provide a lead frame for mounting an optical semiconductor element capable of forming a groove without being affected by the arrangement of a thin portion by etching from the lower surface of the lead frame, and a method of manufacturing the same.

FIG. 1 is a cross-sectional view illustrating a configuration of an example of a lead frame for mounting an optical semiconductor element according to an embodiment of the present invention. FIG. 1A shows an example of a shape in which the thin projection has a flat surface, and FIG. 1B shows an example of a shape in which the thin projection does not have a flat surface. FIG. 1 is a cross-sectional view illustrating a configuration of an example of an optical semiconductor device according to an embodiment of the present invention. It is a figure showing an example of the shape of the general lead frame used conventionally. It is a figure for explaining a series of steps of a manufacturing method of a lead frame concerning an embodiment of the present invention. FIG. 4A is a diagram illustrating an example of a metal plate preparing step of the method for manufacturing a lead frame according to the embodiment of the present invention. FIG. 4B is a diagram illustrating an example of a resist pattern forming step of the method for manufacturing a lead frame according to the embodiment of the present invention. FIG. 4C is a diagram illustrating an example of an etching step of the method for manufacturing a lead frame according to the embodiment of the present invention. FIG. 4D is a diagram illustrating an example of a resist stripping step of the method for manufacturing a lead frame according to the embodiment of the present invention. It is a figure for explaining an example of the manufacturing method of the lead frame with resin concerning an embodiment of the present invention. FIG. 4 is a diagram showing a series of steps for manufacturing an optical semiconductor device 150 using a lead frame 100 with resin. FIG. 6A is a diagram illustrating an example of an optical semiconductor element mounting step in the method for manufacturing an optical semiconductor device according to the embodiment of the present invention. FIG. 6B is a diagram illustrating an example of a wire bonding step of the method for manufacturing an optical semiconductor device according to the embodiment of the present invention. FIG. 6C is a diagram illustrating an example of a sealing step of the method for manufacturing an optical semiconductor device according to the embodiment of the present invention. FIG. 6D is a diagram illustrating an example of the singulation process.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view showing a configuration of an example of a lead frame for mounting an optical semiconductor element according to an embodiment of the present invention. FIG. 1A shows an example of a shape in which the thin projection has a flat surface, and FIG. 1B shows an example of a shape in which the thin projection does not have a flat surface. FIG. 2 is a sectional view showing a configuration of an example of the optical semiconductor device according to the embodiment of the present invention.

  As shown in FIG. 1A, a lead frame 50 for mounting an optical semiconductor element of the present invention is formed by etching a metal plate 10 to form a die pad portion 20 and a lead portion 30. As a material of the metal plate 10, a copper-based alloy is generally used. The thickness of the metal plate 10 is often 0.1 mm to 0.3 mm. The lead part 30 is arranged to face the die pad part 20.

  The die pad section 20 is a member including a region for mounting the optical semiconductor element 110 (see FIG. 2) such as an LED element. The lead portion 30 is a member including a region constituting an internal terminal for electrically connecting the electrode 111 of the optical semiconductor element 110 mounted on the die pad portion 20, and therefore, is opposed to the vicinity of the die pad portion 20. Be placed. However, when the optical semiconductor element 110 is mounted face-down on the lead frame 50, the optical semiconductor element 110 may be mounted across the die pad part 20 and the lead part 30, that is, the optical semiconductor element 110 is mounted on the lead part 30. 110 may be mounted.

  A part or all of the periphery of the die pad portion 20 and the lead portion 30 is etched from a surface (lower surface in FIG. 1) opposite to the LED element mounting surface (upper surface in FIG. 1), so that the die pad portion 20 and the lead are removed. A thin portion 40 having a thickness smaller than the plate thickness is formed inward from the edge of the portion 30. Also, on the upper surface of the lead frame 50, the contour (outer periphery) of the translucent resin portion 130 (FIG. 2) or the contour (outer periphery) of the external resin portion 61 (see FIG. 2) is provided on the die pad portion 20 and / or the lead portion 30. A groove 45 is formed so as to be along. FIGS. 1 and 2 show an example in which the lead portion 30 and the die pad portion 20 are formed on the edge portion of the die pad portion 20 on the side opposite to the die pad portion 20.

  Here, in order to explain the relationship between the thin portion 40, the groove 45, and the external resin portion 61, a configuration of an example of the optical semiconductor device 150 using the lead frame 50 according to the embodiment of the present invention will be described.

  FIG. 2 is a sectional view showing an example of the configuration of the optical semiconductor device 150 according to the first embodiment of the present invention. As described with reference to FIG. 1, the lead frame 50 used in FIG. 2 includes the die pad portion 20 on which the optical semiconductor element 110 is mounted, and the lead portion 30 that is arranged opposite to the die pad portion 20 with a space therebetween. It consists of. The optical semiconductor element 110 is mounted on the upper surface of the die pad section 20, and the electrode 111 of the optical semiconductor element 110 and the lead section 30 are electrically connected by a bonding wire 120 or the like. An external part is formed on the surface of the lead frame 50 including the die pad part 20 and the lead part 30 so as to surround the LED mounting part on which the optical semiconductor element 110 is mounted and the connection part of the lead part 30 electrically connected thereto. A resin portion 61 is formed. At the same time, the space portion where the die pad portion 20 and the lead portion 30 face each other and the thin portion 40 which is thinner than the plate thickness formed inward from the edges of the die pad portion 20 and the lead portion 30 are simultaneously formed. An external resin part 60 is provided. A translucent resin section 130 is provided above the optical semiconductor element 110 and the electrical connection section (terminal section) surrounded by the external resin sections 60 and 61. External resin portions 61 are provided outside the top surface of the die pad portion 20 and outside the top surface of the lead portion 30, respectively. The external resin portions 60 and 61 may be referred to as a lower surface side resin 60 and an upper surface side resin 61 when individually distinguished.

  The thin portion 40 wraps the lead frame 50 from below by the lower surface side resin 60 wrapping from below the thin portion 40 in the molding process, and improves the adhesion between the lead frame 50 and the lower surface side resin 60. In addition, since the effect of suppressing the penetration of the solder flux at the time of reflow is obtained, it is important to form the thin portion 40.

  Further, a groove 45 is formed on the upper surface side of the thin portion 40. The groove 45 is arranged on the upper surface of the die pad portion 20 or the lead portion 30, improves the adhesiveness with the external resin portion 61 or the translucent resin portion 130, and suppresses the spread of the die bonding paste. .

  Due to the recent miniaturization of the optical semiconductor device 150 and the like, the area of the external resin portions 60 and 61 and the like has become smaller, and accordingly, the position where the groove 45 is formed must be arranged near the die pad portion 20 and the edge of the lead portion 30. It has become no longer. In general, when the thin portion 40 is formed by etching, the upper surface is covered with a resist, and the opening of the resist is arranged in a region on the lower surface where the thin portion is to be formed.

  FIG. 3 is a diagram showing an example of the shape of a general lead frame conventionally used. As shown in FIG. 3, the thickness of the thin portion 240 on the outer end portion 46 side is thin, the inner end portion 47 side of the thin portion 240 has an R shape, and has a gentle curved shape toward the outer end portion 46 side. . The outer end 46 of the thin portion 240 refers to the end on the side where the die pad portion 20 and the lead portion 30 face each other, and the inner end 47 of the thin portion 240 is the outer end 46 of the thin portion 240. Refers to the opposite end. If a groove is formed in a thin region near the outer end portion 46 of the thin portion 240, the etching from the upper surface and the etching from the lower surface overlap to make the wall thinner. Therefore, it is difficult to arrange the groove 245 at the outer end 46 of the thin portion 240.

  As shown in FIGS. 1A and 1B, in the lead frame 50 according to the embodiment of the present invention, the thin convex portion 42 is provided in the thin portion 40 on the outer end side 46 from the thin concave portion 41. Thus, the groove 45 can be arranged near the outer end 46 of the thin portion 40.

  The thin portion 40 has a thin convex portion 42 and a thin concave portion 41. As described above, the thin-walled concave portion 41 wraps the lead frame 50 by the lower surface side resin 60 going under the thin-walled portion 40 in the molding process. Thereby, the adhesion to the lower surface side resin 60 can be improved, and the penetration of the solder flux at the time of reflow can be suppressed.

  The thin-walled concave portion 41 includes a region of the thin-walled portion 40 where the depression from the lower surface side is deepest. The thickness of the thin concave portion 41 is, for example, about １ ／ to ／ of the thickness (unprocessed portion) of the metal plate 10. When the thickness of the thin concave portion 41 is less than 1/4 of the thickness of the metal plate 10, the strength of the die pad portion 20 becomes weak, and there is a possibility that deformation or the like occurs. On the other hand, if the thickness of the thin concave portion 41 exceeds 3/4 of the thickness of the metal plate 10, the thickness of the lower surface side resin 60 filled under the thin portion 40 becomes thinner, and the strength of the lower surface side resin 60 decreases. It becomes weak, and the possibility that the lower surface side resin 60 itself peels increases. The thickness of the metal plate 10 is about 0.2 mm, and the thickness of the thin-walled concave portion 41 is preferably 0.05 mm or more and 0.15 mm or less. The thickness of the thin portion 40 is preferably, for example, about ２ of the thickness of the metal plate 10.

  A groove 45 is formed on the upper surface side of the thin convex portion 42. The groove 45 is disposed on the upper surface of the die pad portion 20 or the lead portion 30 to improve the adhesion to the translucent resin portion 130 and suppress the spread of the die bonding paste. The width of the groove 45 is about １ ／ to の of the thickness of the metal plate 10, and the depth of the groove 45 is, for example, １ ／ of the groove width. The shape of the groove 45 is preferably, for example, C-shaped in cross section. Since the cross-sectional shape of the groove 45 is C-shaped, the contact area between the die pad portion 20 and the like in which the groove 45 is formed and the light-transmitting resin portion 130 increases, and the die pad portion 20 and the like and the light-transmitting resin portion 130 Has good adhesion.

  The thin convex portion 42 is disposed closer to the outer end 46 of the thin portion than the thin concave portion 41, and is formed such that the lower surface side has a convex shape. The lower surface of the thin convex portion 42 is formed to be flatter than the thin concave portion 41 having a curved surface, and the surface on the lower surface side is a flat surface. The thin convex portion 42 has a portion that is thicker than the thinnest portion of the thin concave portion 41, and is preferably thicker than the thinnest portion of the thin concave portion 41 in all portions of the thin convex portion 42. The phrase “the thin convex portion 42 has a portion thicker than the thinnest portion of the thin concave portion 41” specifically means that the upper surface of the lead frame 50 and the thin convex portion 42 are perpendicular to the upper surface of the lead frame 50. Is larger than the thickness Q of the thinnest portion of the thin concave portion 41. In other words, at least a portion of the surface of the lower surface of the thin convex portion 42 is located below the lower surface of the thinnest portion of the thin concave portion 41 in the height direction. The thin convex portion 42 only needs to have a thickness in which the groove 45 can be formed and the thin portion 40 is not easily deformed. The thickness between the lower surface of the thin convex portion 42 and the lower surface of the groove 45 on the upper surface of the thin portion 40 needs to be at least 0.03 mm or more. If the thickness is less than 0.03 mm, the thickness may be too small, the outer end 46 may be broken, and problems such as cutting may occur. The thickness between the lower surface of the groove 45 and the lower surface of the thin convex portion 42 is preferably 0.05 mm to 0.07 mm. For this reason, the thickness between the upper surface of the thin portion 40 and the lower surface of the thin convex portion 42 is about the sum of the groove depth of the groove 45 on the upper surface of the thin portion 40 and 0.03 mm to 0.07 mm. . Also, the lower surface of the thin convex portion 42 may not be flat. As described above, the thin convex portion 42 is formed for disposing the groove 45 on the upper surface thereof, and it is sufficient that sufficient strength can be maintained even when the groove 45 is processed. However, irregularities may be provided as long as they do not hinder the groove processing. The shape of the thin convex portion 42 is not limited to a shape in which the lower surface side is a flat surface as shown in FIG. 1A, and may be a shape having no flat surface as shown in FIG. 1B. . The thin-walled convex portion 42 shown in FIG. 1B has a mountain shape with a lower surface facing downward and an R shape on the lower surface. In other words, the thin convex portion 42 includes a partial convex portion having a curvature that changes on a part of the lower surface side, and the region where the partial convex portion is formed is located at the lowest position in the thin convex portion 42. The partial convex portion is formed immediately below the groove portion 45, and preferably, the partial convex portion is formed immediately below a point where the depth of the groove portion 45 is deepest. Since the lower surface of the thin-walled projection 42 does not have a flat surface, even if the length of the thin-walled section 40 (the length from the outer end 46 to the inner end 47 of the thin-walled section 40) is short, the thin-walled projection 42 can be easily formed. Can be formed. This is effective for a small semiconductor device.

  The length of the thin portion 40 of the die pad portion 20 and the lead portion 30 (the length from the outer end 46 to the inner end 47 of the thin portion 40) is equal to or greater than the plate thickness. The effect of the resin adhesion is exhibited when the length to the inner end portion 47 is 0.1 mm or more, but as described above, the groove 45 is arranged on the upper surface of the thin convex portion 42 and the thin concave portion 41 is formed. It is preferable that the length of the thin portion 40 of the die pad portion 20 and the lead portion 30 is at least equal to or greater than the plate thickness. If the distance is less than the plate thickness of the lead frame 50, it is difficult for the thin portion 40 to exhibit the original effect of improving the resin adhesion. Further, the length of the thin portion 40 can be freely set as long as no problem occurs in die bonding or wire bonding and an external connection area can be secured. If the thin concave portion 41 is securely formed, the thin convex portion 42 and the groove 45 on the upper side of the thin portion 40 may be arranged other than the outer end 46 of the thin portion 40. For example, the groove 45 may be formed between the outer end 46 and the inner end 47 of the thin portion 40.

  The thin portion 40 including the thin concave portion 41 and the thin convex portion 42 is preferably formed on the surface of the die pad portion 20 facing the lead portion 30, that is, on the die pad portion 20 side inside the lead frame 50. The exposed surfaces (flat surfaces) of the lower surfaces of the die pad portion 20 and the lead portion 30 become external terminal portions to which external devices can be connected when completed as an optical semiconductor device, and the connection between the external terminal portions and the external device is made of solder balls. And the like. On the other hand, since the optical semiconductor element 110 is mounted on the upper surface of the die pad section 20, the plane areas of the die pad section 20 and the lead section 30 are significantly different, for example, the ratio of the plane area of the die pad section 20 to the plane area of the lead section 30. Is about 2: 1. Then, the thin portion 40 on the side opposite to the die pad portion 20 and the lead portion 30 can have a shape that is much longer in the die pad portion 20 than in the lead portion 30. The groove 45 may be formed for the purpose of improving the adhesion of the translucent resin portion 130 and at the same time suppressing the spread of the die bonding paste. In this case, the groove 45 needs to be formed on the periphery of the die pad portion 20 so as to surround the LED element. Therefore, it is preferable that the thin convex portion 42 and the groove 45 are formed in the die pad portion 20 from the viewpoint of less loss of space.

  However, the place where the thin convex portion 42 and the groove 45 are formed is not limited to the inside of the die pad portion 20, and may be further formed on the lead portion 30 if necessary, or the die pad portion 20 and the lead portion may be formed. 30 may be formed on the outer upper surface opposite to the opposing surface. 1 and 2, the thin portion 40 is not formed outside the die pad portion 20 and the lead portion 30, but the thin portion 40 is further provided outside the die pad portion 20 and the lead portion 30. Is also good.

  As described above, at least one thin concave portion 41, one thin convex portion 42, and one groove 45 are formed on the surface of the die pad portion 20 facing the lead portion 30, and a general thin portion including only the thin concave portion 41 is formed at other locations. 40 may be formed.

  Next, a method for manufacturing the lead frame 50, the lead frame with resin 100, and the optical semiconductor device 150 according to the embodiment of the present invention will be described.

  FIG. 4 is a diagram for explaining a series of steps of the method for manufacturing a lead frame according to the embodiment of the present invention.

  FIG. 4A is a diagram illustrating an example of a metal plate preparing step of the method for manufacturing a lead frame according to the embodiment of the present invention. As shown in FIG. 4A, first, a flat metal plate 10 is prepared. As a material of the metal plate 10, a copper alloy can be used. The prepared metal plate 10 is degreased and washed to remove unnecessary dust and organic matter.

  FIG. 4B is a diagram illustrating an example of a resist pattern forming step of the method for manufacturing a lead frame according to the embodiment of the present invention. As shown in FIG. 4B, in the resist pattern forming step, resist masks 70 and 75 are formed using an etching resist so that predetermined patterns of the die pad portion 20 and the lead portion 30 are formed. More specifically, a photosensitive resist is applied to the upper and lower surfaces of the metal plate 10. Then, a predetermined pattern is exposed through a photomask. Thereafter, development is performed to produce resist masks 70 and 75.

  In the resist masks 70 and 75, in addition to the formation of the die pad portion 20 and the lead portion 30, the thin portion 40 is formed on the surface (the lower surface in FIG. 2) opposite to the mounting surface (the upper surface) of the optical semiconductor element 110 by the etching process. It is formed with a mask pattern as formed. In the thin portion 40, a thin convex portion 42 and a thin concave portion 41 are formed. In a region 11 where the thin concave portion 41 is to be formed, a resist mask 70 is formed on the upper surface, and an opening 76 is formed on the lower surface. In the region 12 where the thin convex portion 42 is to be formed, a resist mask 70 is formed on the upper surface except for the groove 45. On the lower surface, an etching rate control resist 77 is formed. The etching rate control resist 77 is arranged in a line along the contour (outer periphery) of the die pad portion 20 and the lead portion 30. In addition, at least one line is also arranged inside thereof. Since the groove 45 is formed on the upper surface of the thin convex portion 42, the upper surface side of the region where the groove 45 is formed is the opening 71.

  FIG. 4C is a diagram illustrating an example of an etching step of the method for manufacturing a lead frame according to the embodiment of the present invention. As shown in FIG. 4C, in the etching step, the openings 71 and 76 that are not covered with the resist masks 70 and 75 are etched with an etchant. Thus, the die pad portion 20 and the lead portion 30 are formed.

  Since the upper surface of the region 12 where the thin concave portion 41 is formed is covered with the resist mask 70, the upper surface is not etched, and the lower surface becomes the opening 76, so that the thin concave portion 41 is etched.

  Since the upper surface of the thin protrusion 42 is covered with the resist mask 70 except for the groove 45, the upper surface is not etched, and the lower surface is provided with an etching rate control resist 77. For this reason, at the time of the etching process, the etching solution is etched from the gap between the line-shaped resists 77, and the etching rate is lower than that of the openings 76 without the resist mask 75, and the etching depth is shallower. By adjusting the position and size of the etching rate control resist 77, the number of lines, and the like, the thin convex portions 42 having desired positions, widths, depths, and the like are formed. The resist 77 for controlling the etching rate may be arranged in a line. In this case, the cross-section is line-shaped, and the cross section is downward, and the lower surface side is R-shaped. Since the groove 45 is formed on the upper surface side of the mountain-shaped R-shaped portion, the position of the groove 45 is limited, and the size and the depth are also limited. Therefore, it is preferable that the etching rate control resist 77 be arranged in a line along the contours of the die pad section 20 and the lead section 30 and be arranged in at least one line inside thereof. Thus, a thin convex portion 42 having a thickness greater than that of the thin concave portion 41 can be formed. Note that the lower surface of the thin convex portion 42 tends to have a downward convex shape at the position where the etching rate control resist 77 is arranged.

  The position and size of the etching rate control resist 77, the number of lines, and the like are adjusted so as not to affect the processing of the groove 45 on the upper side of the thin portion 40. In addition, since etching conditions such as the direction of the etching solution and the nozzle of the etching nozzle are also affected, these are appropriately adjusted as necessary.

  Since the upper side of the thin convex portion 42 has an opening on the upper side, a groove 45 is formed by etching.

  FIG. 4D is a diagram showing an example of a resist peeling step in the method for manufacturing a lead frame according to the present invention. As shown in FIG. 4D, in the resist stripping step, the resist masks 70 and 75 and the etching rate control resist 77 are stripped using a stripping agent. Thereby, the lead frame for an optical semiconductor device of the present invention is completed.

  After that, if necessary, the optical semiconductor element 110 and the bonding wires 120 surrounded by the upper surface side resin 61 at least in the openings of the external resin parts 60 and 61 of the die pad part 20 and the lead part 30 of the lead frame 50, etc. Thus, a plating layer is formed around the connection portion electrically connected to the lead portion 30. In the plating process, partial plating or entire plating may be performed on the area of the opening of the external resin parts 60 and 61.

  When partial plating is performed in the area of the openings of the external resin parts 60 and 61, a method of mechanically covering a portion not to be plated with a mask or the like and forming an opening only in a portion to be partially plated and performing plating is used. You may.

  The lead frame 50 on which the die pad portion 20 and the lead portion 30 are formed and a predetermined plating layer (not shown) is formed. It may be attached to the surface opposite to the LED mounting surface.

  FIG. 5 is a diagram for explaining an example of a method for manufacturing a lead frame with a resin according to the present invention.

  FIG. 5 is a view showing an example of a manufacturing process of a lead frame with a resin in the manufacturing method of the optical semiconductor device of the present invention. As shown in FIG. 5, in the lead frame with resin manufacturing process, the upper surface side resin 61 is formed on the lead frame 50 by transfer molding or injection molding the manufactured lead frame 50. As the upper surface side resin 61, a thermosetting resin is generally used. The upper surface side resin 61 is formed on the lead frame 50, and the lower surface side resin 60 is simultaneously filled in the space where the die pad portion 20 and the lead portion 30 face each other. The lower surface side resin 60 is formed so as to surround an optical semiconductor element 110 described later and a periphery of a connection portion electrically connected to the lead portion 30 by wire bonding or the like. The inner surface of the outer resin portion 61 is formed in a tapered shape so that light generated from the LED element 80 is reflected upward by the outer resin portion 61. Through this step, the lead frame with resin 100 is completed.

  FIG. 6 is a view showing a series of steps for manufacturing the optical semiconductor device 150 using the lead frame 100 with resin.

  FIG. 6A is a diagram illustrating an example of an optical semiconductor element mounting step of the method for manufacturing an optical semiconductor device according to the present invention. As shown in FIG. 6A, in the optical semiconductor element mounting step, the optical semiconductor element 110 is mounted on the die pad portion 20 by using the obtained lead frame 100 with resin. A bonding member is applied to the surface of the die pad portion 20 in advance, and the optical semiconductor element 110 is fixed on the die pad portion 20.

  FIG. 6B is a diagram illustrating an example of a wire bonding step in the method for manufacturing an optical semiconductor device according to the present invention. As shown in FIG. 6B, in the wire bonding step, the electrode 111 of the optical semiconductor element 110 and the lead portion 30 are electrically connected using the bonding wire 120 or the like.

  FIG. 6C is a diagram illustrating an example of a sealing step of the method for manufacturing an optical semiconductor device according to the present invention. As shown in FIG. 6C, in the sealing step, the optical semiconductor element 110 surrounded by the upper surface side resin portion 61 and the peripheral portion of the connection portion electrically connected to the lead portion 30 by the bonding wire 120 or the like. Is molded with the translucent resin part 130.

  FIG. 6D is a diagram illustrating an example of the singulation process. Lastly, in the singulation step, when a plurality of optical semiconductor devices 150 are arranged so as to have a predetermined package size, singulation is performed. If they are molded in a lump, they are cut into individual pieces by sewing or the like.

[Example 1]
Next, an embodiment of a method for manufacturing a lead frame according to the present invention will be described. For convenience of explanation, components corresponding to the components described above are denoted by the same reference numerals.

  As the metal plate 10 for a lead frame, a band-shaped copper material (EFTEC-64T, manufactured by Furukawa Electric Co., Ltd.) having a thickness of 0.2 mm and a width of 180 mm was used. First, the metal plate 10 for a lead frame was degreased and washed. Thereafter, a resist layer for forming a pattern of the lead frame 50 was formed. Specifically, first, a photosensitive resist having a thickness of 0.02 mm was applied to the surface of the metal plate. As the resist, a negative photosensitive resist (manufactured by Asahi Kasei E-materials Corporation) was used. Next, the resist layer was exposed using a glass mask so that the die pad portion 20 and the lead portion 30 had a predetermined pattern. Thereafter, the resist was developed to produce a resist mask for etching.

  Further, a peripheral thin portion 40 of the die pad portion 20 and the lead portion 30 was formed. The width of the thin portion 40 was set to be 0.25 mm. In addition, the thickness of the thin-walled concave portion 41 was set to 0.08 mm. The thin portion flat portion was set such that the thickness of the thin portion 40 was 0.12 mm and the thickness of the thin portion 40 was 0.12 mm from the periphery of the die pad portion 20 and the lead portion 30. The thin portion upper groove portion 45 was set such that the groove width was 0.05 mm and the depth was 0.06 mm.

  The resist for etching rate control is one in a line along the periphery of the die pad part 20 and the lead part 30 on the lower side of the metal plate, and one in the line 0.05 mm apart from the inside of the metal pad, for a total of two resists. The resist was arranged in a line.

  Thereafter, etching was performed with an etching solution. A ferric chloride solution was used as an etching solution. The blowing direction of the etching solution, the blowing pressure, and the like were appropriately adjusted as needed.

  After the etching was completed, the resist mask was peeled off to form the die pad portion 20 and the lead portion 30, the thin convex portion 42, the thin concave portion 41, and the groove 45.

  Next, noble metal plating was performed to form a plating layer. The noble metal plating was performed with Ag plating and a plating thickness of 3.0 μm. The plating was performed on the entire front and back surfaces.

  After that, each lead frame was cut into a sheet to complete the lead frame.

  Also, using the lead frame 50, the external resin portions 60 and 61 were molded to produce the lead frame 100 with resin. Then, the LED element was mounted using the lead frame 100 with resin. After the wire bonding, the light-transmitting resin portion 130 was molded and then subjected to a sawing process to be singulated to complete the optical semiconductor device 150.

〔実施例２〜３、比較例〕
表１に実施例２〜３、比較例の各設定を示す。なお、実施例２のエッチング速度制御用レジストは、金属板下側のダイパッド部２０とリード部３０の周縁に沿ってライン状に１本、また、その内側に０．０５ｍｍ離してライン状に１本、計３本のライン状にレジストを配置した。ラインの幅は、適時調整した。

[Examples 2 and 3, Comparative Example]
Table 1 shows each setting of Examples 2 and 3 and Comparative Example. In addition, the resist for controlling the etching rate according to the second embodiment has one line in a line along the periphery of the die pad portion 20 and the lead portion 30 under the metal plate, and one line in the line with a distance of 0.05 mm inside. The resist was arranged in a total of three lines. The width of the line was adjusted as appropriate.

In the third embodiment, the setting of the first embodiment is such that the position of the thin portion flat portion is moved from the outer end portion 46 toward the thin portion concave portion by 0.05 mm. The resist for controlling the etching rate of the third embodiment is one in a line along the periphery of the die pad part 20 and the lead part 30 on the lower side of the metal plate, and two in a line at a distance of 0.05 mm inside the resist. The resist was arranged in a total of three lines.
In order to move the thin portion flat portion by 0.05 mm, the width of one line is set to be smaller than the other two lines in a line along the periphery. Other settings are the same manufacturing method as in the first embodiment.

  In the comparative example, the thin convex portion 42 was not formed, and an opening was formed below the thin portion without forming a resist for controlling the etching rate. Others are the same manufacturing methods as the first embodiment.

  In the examples 1 to 3 and the comparative example, at the time of completion of the lead frame 50, the die pad portion 20 and the thin portion 40 of the lead portion 30 were observed with a stereoscopic microscope. In the comparative example, a plurality of locations where breakage occurred near the thin portion were detected. In Examples 1 to 3, the thin portion upper groove portion 45 could be formed on the thin portion flat portion, and no problem such as breakage or deformation occurred in the thin portion 40.

  The preferred embodiments and examples of the present invention have been described above in detail, but the present invention is not limited to the above-described embodiments and examples, and does not depart from the scope of the present invention. Various modifications and substitutions can be made to the embodiment.

DESCRIPTION OF SYMBOLS 10 Metal plate 20 Die pad part 30 Lead part 40 Thin part 41 Thin concave part 42 Thin convex part 45 Groove 46 Outer end part 47 Inner end part 50 Lead frame 60, 61 External resin part 100 Resin lead frame 110 Optical semiconductor element 120 Bonding wire 130 translucent resin part 150 optical semiconductor device

Claims (9)

A lead frame for mounting an optical semiconductor element having a die pad portion on which the optical semiconductor element can be mounted, and a lead portion arranged to face the die pad portion,
At least one of the die pad portion and the lead portion has a thin portion in which a part of the lower surface is thinned,
The thin portion has a thin concave portion including a region where the depression from the lower surface side is deepest, and a thin convex portion which is thicker than the thinnest portion of the thin concave portion and has a convex shape on the lower surface side,
On the upper surface side of the thin convex portion, a groove is formed ,
Wherein the lower surface of the surface of the thin projections, the lead frame Ru flat der than the thin recess. The thin convex portion is formed on an outer end side of the thin portion,
The lead frame according to claim 1, wherein the thin recess is formed on an inner end side of the thin portion.   The lead frame according to claim 2, wherein the thin convex portion is formed on a surface of the die pad portion facing the lead portion. The thickness of the thin recess, a lead frame according to any one of claims 1 to 3 is 0.05mm or 0.15mm or less. The thin recess and the thin protrusions, the lead frame according to any one of claims 1 to 4 is provided in the die pad. The lead frame according to claim 5 , wherein the lead portion has the thin portion that does not have the thin convex portion. A first mask portion covering an area other than the first opening on the upper surface side of the metal plate, and a groove formed between the first mask portion and a part of the first opening covering an area inside the first opening. A top mask forming step of forming a top mask having a second mask portion disposed at a possible interval; and
A third mask portion that covers an area other than a second opening including the first opening on the upper surface side on a lower surface side of the metal plate; and the groove on the upper surface side in the second opening. Forming a lower mask having a fourth mask portion having an intermittent pattern for limiting an etching rate so as to include a region in which a lower mask can be formed; and
The metal plate covered with the upper surface side mask and the lower surface side mask is etched from both the upper surface side and the lower surface side, and the first opening overlaps the second opening, and the first opening overlaps with the first opening. Through holes in regions where the fourth mask portion is not formed, a thin recess on the lower surface side of a region where the second opening overlaps the first mask portion, and a region covered with the fourth mask portion An etching step of forming the groove in a region on the upper surface side between the first mask portion and the second mask portion, the thin convex portion being thicker than the thin concave portion on the lower surface side of
A method of manufacturing a lead frame for mounting an optical semiconductor device, comprising: a mask removing step of removing the upper surface side mask and the lower surface side mask. The method for manufacturing a lead frame according to claim 7 , wherein at least a part of the second mask portion and the fourth mask portion are formed so as to overlap with each other. The intermittent pattern of the fourth mask portion includes one outer peripheral mask portion disposed along the outer periphery on at least one of the opposing surfaces of the die pad portion and the lead portion, and an outer peripheral mask portion. 9. The method for manufacturing a lead frame according to claim 8 , comprising at least one mask portion disposed.

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