JP4486451B2 - LIGHT EMITTING DEVICE, LEAD FRAME USED FOR THE LIGHT EMITTING DEVICE, AND LEAD FRAME MANUFACTURING METHOD - Google Patents

Description

  The present invention relates to a light-emitting device, a method for manufacturing the same, and a lead frame used for manufacturing the light-emitting device, and in particular, an effective technique applied to a surface-mounted light-emitting device using a light-emitting element such as a light-emitting diode (LED). It is about.

  Conventionally, in a light-emitting device using a light-emitting element such as a light-emitting diode, a first lead frame and a second lead frame are inserted into a through-hole of the mounting substrate and soldered together with an insertion mounting type on the surface of the mounting substrate. There is a surface mount type that solders to a provided pad (terminal).

  The present invention relates to the latter type of light emitting device of the surface mount type, etc., but the lead frame of the conventional surface mount type light emitting device is generally a flat body, and the lead frame of the light emitting element is mounted. Since the mounting part is also a part of the flat body, when the light emitting element is mounted on the mounting part, a phenomenon that an alloy layer such as solder wraps around the side surface or the surface layer of the light emitting element has occurred. For this reason, a short circuit phenomenon occurs in the electric circuit of the packaged light emitting device, and the light emitting function of the light emitting element is impaired.

  FIG. 7 shows a conventional surface mount type light emitting device. In this light emitting device, a part of a flat lead frame is used as a cup-shaped bottom portion B, and a light emitting element 31 is adhered to the portion (see Patent Document 1). In the light emitting device 30, the flat bottom B is formed at the center of the cup shape in which the periphery is inclined downwardly toward the second lead frame 34 side of the first lead frame 33, and the reflecting plate L of the light emitting element 31. The light emitting element 31 is joined to the bottom B using solder 37. By doing so, heat generated when the light emitting element 31 is operated can be radiated to the outside of the light emitting device via the bottom B, and the light emission efficiency can be stabilized. Further, the reflecting plate L can make the light emitting function effective.

The light emitting device 30 has first and second flat lead frames 33, one electrode of the light emitting element 31 is connected to the bottom B of the first lead frame 33 by a solder 37, and the other of the light emitting elements 31 is connected. These electrodes are connected to the second lead frame 34 by bonding wires 35. The light emitting element 31, the bonding wire 35, and the like are sealed with a sealing insulator.
JP 2003-174200 A

  However, according to the surface mount type light emitting device 30, the bottom B of the cup-shaped surface of the first lead frame 33 is a flat surface, and thus the solder 37 may wrap around the side surface or the surface layer of the light emitting element 31. There is a risk that the above-mentioned problems such as short circuit may occur.

  Accordingly, an object of the present invention is to eliminate such a problem as much as possible and prevent a short circuit accident by preventing the conductive adhesive or the like (solder etc.) from wrapping around the light emitting element. It is an object of the present invention to provide a surface mount type light emitting device and a method for manufacturing the same, and a lead frame used for manufacturing the light emitting device.

In order to achieve the above object, a light emitting device according to the present invention includes a light emitting element, a first lead frame electrically connected to the first electrode of the light emitting element, and a second electrode of the light emitting element. A second lead frame to be connected, the light emitting element, a connecting portion between the first electrode and the first lead frame of the light emitting element, and an insulator for sealing the connecting portion between the second electrode of the light emitting element and the second lead frame The first lead frame has a flat top surface, and one or a plurality of convex shapes of the same height are formed on the connection portion side, and a concave mounting portion is formed on the back surface side. The area of the upper surface of the mounting portion is formed to be equal to or smaller than the area of the light emitting element, and the light emitting element is bonded to the upper surface of the mounting portion.

  In this case, the height of the mounting portion is preferably 0.01 to 0.15 mm.

Moreover, it is preferable that a lattice-like groove is provided on the upper surface of the mounting portion .

  In this case, the height of the mounting portion is preferably 0.01 to 0.15 mm.

  Furthermore, it is preferable that the first lead frame is composed of a conductor plate having a plurality of protrusions having a flat top surface at a predetermined position and one or the same height.

  In this case, it is preferable that the step of forming the semiconductor device mounting portion includes a step of adjusting the height by pressing the first lead frame halfway and then pressing it in the reverse direction.

  According to the present invention, the mounting portion of the light-emitting element has a very simple structure, but prevents the occurrence of short-circuit accidents and improves the mounting reliability by accurately preventing the adhesive such as solder from wrapping around the light-emitting element. Can be planned. In addition, by making the upper surface of the mounting portion flat, the light emitting element can be reliably mounted on the mounting portion. Further, by making the area of the mounting portion equal to or smaller than the area of the mounting surface of the light emitting element, it is possible to further prevent the adhesive from entering the light emitting element. In addition, since the first lead frame has a convex shape on the connection portion side and a concave shape on the back surface side, the surface area of the lead frame is increased and heat dissipation is improved.

  In addition, according to the method for manufacturing a light emitting device of the present invention, not only progressive transfer processing but also processing by a crank press that further increases the yield is possible, and the first lead frame and the second lead frame are simultaneously formed. You can also. In addition, a mounting portion for adhering the light emitting element to the first lead frame can be formed simultaneously with the simultaneous formation.

  Furthermore, according to the lead frame used for manufacturing the light emitting device of the present invention, the mounting portion for bonding the optical element provided on the first lead frame is a portion where a convex portion higher than the surrounding lead frame surface is formed. Thus, it is possible to reliably prevent the adhesive such as solder from wrapping around the light emitting element.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view of a light emitting device of the present invention. The light emitting device 1 includes a light emitting element 11, a first lead frame 13 electrically connected to a first electrode provided on the chip lower surface 11 a of the light emitting element 11, and a second lead provided on the chip upper surface 11 b of the light emitting element 11. A second lead frame 14 electrically connected to the electrode; a bonding wire 15 connecting the second electrode of the light emitting element 11 and a connecting portion of the second lead frame 14; and the light emitting element 11 and the connecting portion. The sealing insulator 16 is made of an epoxy resin that seals the periphery, and the connection terminal portions 13a and 14a of the first lead frame 13 and the second lead frame 14 to external devices are connected to the sealing insulator 16. The first lead frame 13 has a plurality of protrusions having one or the same height for bonding and mounting the light emitting element 11 on the first lead frame 13. (Hereinafter, referred to as mounting part.) 13A is formed, it is to adhere the chip lower surface 11a serving as the lower side of the light emitting element 11 by the upper surface 13b low melting access for eutectic solder 17 of the mounting portion 13A.

  In the light emitting element 11, a light emitting layer is formed by laminating an n-type semiconductor layer and a p-type semiconductor layer on a substrate (not shown), and a p-side electrode as a second electrode is formed on the upper surface of the light-emitting element 11 and a first electrode is formed on the lower side of the substrate. An n-side electrode as an electrode is formed.

  FIG. 2 is a schematic cross-sectional view of another embodiment of the light emitting device of the present invention. The light emitting device 1 has a mounting portion 13A formed in two convex shapes, and has the same structure as the light emitting device 1 of FIG. 1, and the same reference characters are used for the same portions. Omitted.

  FIG. 3 shows the first lead frame 13. FIG. 3A shows a case where the mounting portion 13A is formed with one convex shape, and FIG. 3B shows a case where the mounting portion 13A has two convex shapes. This is the case. According to FIG. 5A, eutectic solder 17 is applied or dropped on the upper surface 13a of the mounting portion 13A. Further, the light emitting element 11 is bonded to the upper surface 13a of the mounting portion 13A so as to sandwich the eutectic solder 17 therebetween. In this case, the area of the upper surface 13a of the mounting portion 13A is formed to be equal to or smaller than the area of the chip lower surface 11a of the light emitting element 11. Further, the height of the mounting portion 13A is set to 0.01 to 0.15 mm. Similarly, according to FIG. 2B, eutectic solder 17 is applied or dropped onto the upper surface 13a of the mounting portion 13A. Further, the light emitting element 11 is bonded to the upper surface 13a of the mounting portion 13A so as to sandwich the eutectic solder 17 therebetween. In this case, the area of the upper surface 13a of the mounting portion 13A is formed to be equal to or smaller than the area of the chip lower surface 11a of the light emitting element 11. Further, the height of the mounting portion 13A is set to 0.01 to 0.15 mm.

  In the first lead frame 13 provided with such a mounting portion 13A, when the light emitting element 11 is bonded to the mounting portion 13A via the eutectic solder 17, the eutectic solder 17 is attached to the chip side surface 11c or the chip upper surface of the light emitting element 11. It is possible to prevent climbing to 11b. The effect is greater in FIG. 2 (FIG. 3B) than in FIG. 1 (FIG. 3A). In the above embodiment, eutectic solder is used for bonding the semiconductor light emitting element to the mounting portion, but the present invention is not limited to this, and a conductive adhesive such as Ag paste may be used.

Further, a plurality of grooves may be formed on the upper surface of the mounting portion 13a formed in the convex shape of the first lead frame. In this case, as shown in FIGS. 4A and 4B, a lattice-like groove (mesh-shaped groove) including grooves 28 extending in the width direction of the lead frame is provided on the upper surface of the mounting portion 13a.
By forming a groove on the upper surface of the mounting portion 13a formed on the convex portion, even when excessive adhesive such as solder is supplied to the mounting surface, there is an effect of preventing the adhesive material from wrapping around. The applied force that occurs is also mitigated.
In addition, it is preferable that the depth of the groove | channel formed in the convex part upper surface of this 1st lead frame is 3-20 micrometers, and the pitch of a groove | channel is 0.04-0.2 mm.

  FIG. 5 is a schematic view showing a method for forming the first lead frame 13 and the second lead frame 14. (A) is a schematic diagram before processing, FIG. (B) is a schematic diagram of a processing posture, (c) is a schematic diagram at the end of processing, and (d) is a diagram of the mounting portion 13A. The outline figure of processing which adjusts height finely is shown. The first lead frame 13 and the second lead frame 14 are manufactured using the conductor plate 12 which is a flat thin plate made of Cu or the like as a material (a). In the conductor plate 12 placed on the dies D1 and D2, the punch P moves downward in the direction of the dies D1 and D2, and pressurizes the conductor plate 12 (b). The punch P is further lowered, and the conductor plate 12 is reversed and raised with the position of the half-drawn state as the bottom dead center (c). By this series of operations, one mounting portion 13A is formed downward. FIG. 4D shows a processing step for finely adjusting the height of the mounting portion 13A by pressing the mounting portion 13A formed by half punching with a press mold PM from below.

  FIG. 6 is a schematic diagram showing a method of forming the first lead frame 13 and the second lead frame 14 using the conductor plate 12 in which a plurality of mounting portions 13A (only one is shown) are formed in advance at predetermined intervals. It is. FIG. 4A is a schematic diagram before machining, FIG. 4B is a schematic diagram of a machining posture, and FIG. 4C is a schematic diagram at the end of machining. In the conductor plate 12 placed on the dies D1 and D2, the punch P descends in the direction of the dies D1 and D2, and pressurizes the conductor plate 12. The punch P further descends and reverses and rises with the position where the conductor plate 12 is removed as the bottom dead center. By this series of operations, the first lead frame 13 having the mounting portion 13A and the flat second lead frame 14 can be manufactured at the same time. 5 and 6, a large number of conductor plates 12 are preferably supported in parallel by a frame-like metal frame, but are omitted from the drawing.

  Next, the manufacturing method of the light emitting device 1 according to the present invention will be described step by step. The manufacturing procedure of the light emitting device 20 is substantially the same.

  Procedure 1: Formation of the mounting portion 13A of the first lead frame 13. A pair of lead frames of the first lead frame 12 and the second lead frame 14 is formed on the conductor plate 12 by the press forming process described above.

  Procedure 2: Eutectic solder 17 is applied (or dropped) on the upper surface 13a of the mounting portion 13A.

  Procedure 3: Attaching the light emitting element 11 to the mounting portion 13A.

  Procedure 4: Wire bonding wires. The p-side electrode on the chip upper surface 11b and the second lead frame 14 are connected.

  Procedure 5: Resin coating. The light emitting element 11, the first lead frame 13, the second lead frame 14, and the bonding wire 15 are sealed with a sealing insulator 16 made of epoxy resin.

  According to the above procedure, when the second lead frame 14 is energized with the positive electrode side and the first lead frame 13 with the negative electrode side, current flows from the second lead frame 14 to the first lead frame via the bonding wire 15. 13 flows. At this time, since the light emitting element 11 is prevented from being short-circuited due to the wraparound phenomenon of the solder 17, electrons flow from the n-type semiconductor layer to the p-type semiconductor layer and emit light from the light emitting layer.

  As described above, according to the light emitting device according to the present invention, the mounting portion of the light emitting element has a very simple structure, and by preventing the conductive adhesive such as solder from wrapping around the light emitting element, the short circuit accident can be prevented. The mounting reliability can be improved. In addition, by making the upper surface of the mounting portion flat, the light emitting element can be reliably mounted on the mounting portion. Further, by making the area of the mounting portion equal to or smaller than the area of the mounting surface of the light emitting element, it is possible to further prevent the adhesive from entering the light emitting element.

In addition, according to the method for manufacturing a light emitting device of the present invention, not only progressive transfer processing but also processing by a crank press that further increases the yield is possible, and the first lead frame and the second lead frame are simultaneously formed. You can also. In addition, a mounting portion for adhering the light emitting element to the first lead frame can be formed simultaneously with the simultaneous formation. In addition to the progressive transfer device, it can be easily manufactured by a device such as a brake press or a turret punch press. This is because the conductor plate 12 is an extremely thin conductive plate, so that not only the mounting portion itself but also the lead frame can be easily pressed.

  Furthermore, according to the lead frame used for manufacturing the light emitting device of the present invention, the mounting portion for bonding the light emitting element provided on the first lead frame is a portion where a convex portion higher than the surrounding lead frame surface is formed. Thus, it is possible to reliably prevent the adhesive such as solder from wrapping around the light emitting element.

  Furthermore, in the resin coating in the above-described procedure 5, when sealing with the sealing insulator 16 made of epoxy resin, the back surface side of the first lead frame and the second lead frame is covered and shown by a dotted line in FIG. The lower insulator 16A can also be formed. When the lower insulator 16A is formed, the lead frame is covered with resin, so that the heat dissipation is inferior to that of the above-described embodiment, but the adhesion between the sealing insulator and the lead frame is improved and the peeling between the two is reduced. To do. In particular, since the back surface of the lead frame is concave, it has excellent adhesion to the sealing insulator.

It is a cross-sectional schematic diagram of one Example of the light-emitting device of this invention. It is a cross-sectional schematic diagram of the other Example of the light-emitting device of this invention. The structure of a 1st lead frame is shown, (a) is a 1st lead frame which has the mounting part formed in one convex shape. (B) is a first lead frame having a mounting portion formed in two (plural) convex shapes. (A) is a partial front view of the lead frame for explaining the groove shape formed on the surface of the first lead frame, and (b) shows the groove shape formed on the surface of the first lead frame. It is a fragmentary sectional view of the lead frame for doing. It is a schematic diagram of a manufacturing method of a lead frame, and (a) is a schematic diagram before processing. (B) is a schematic diagram of a processing posture. (C) is a schematic diagram at the end of processing. (D) is a schematic diagram of a processing step for finely adjusting the height of the mounting portion. It is a schematic diagram of the manufacturing method of a lead frame using the conductor board which mounted the mounting part beforehand at predetermined intervals, and (a) is a schematic diagram before processing. (B) is a schematic diagram of a processing posture. (C) is a schematic diagram at the end of processing. It is an Example figure of the conventional surface mount type light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,30 Light-emitting device 11, 31 Light-emitting element 12 Conductor plate 13, 33 1st lead frame 13A, B Mounting part 14, 34 2nd lead frame 15, 35 Bonding wire 16, 36 Sealing insulator 17, 37 Solder

Claims (3)

A light emitting element, a first lead frame electrically connected to the first electrode of the light emitting element, a second lead frame electrically connected to the second electrode of the light emitting element, the light emitting element, and the light emitting element A surface-mount type light emitting device comprising a connecting portion between a first electrode and a first lead frame, and an insulator that seals a connecting portion between the second electrode of the light emitting element and the second lead frame,
The first lead frame has a flat upper surface, and a plurality of convex shapes having one or the same height on the connection portion side and a concave mounting portion on the back surface side. The area of the upper surface of the mounting portion is A light emitting device, wherein the light emitting element is formed to be equal to or smaller than an area of the light emitting element, and the light emitting element is bonded to the upper surface of the mounting portion.   The light emitting device according to claim 1, wherein a height of the mounting portion is 0.01 to 0.15 mm.   The light emitting device according to claim 1, wherein a lattice-like groove is provided on the upper surface of the mounting portion.

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