JP5082710B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device in which a light emitting element is formed by die bonding to a metal member.

  Conventionally, there has been proposed a light emitting device in which a light emitting element is die-bonded to a die pad portion made of a metal member that covers the surface of an insulating substrate and is embedded in a package (sealing member). In this light emitting device, when die bonding is performed on the die pad portion formed on the surface of the insulating substrate, an appropriate amount of a heat-meltable die bond member such as solder paste is applied to the surface of the die pad portion. It is manufactured by a method in which a light emitting element is placed on a member and the die bonding member is reflowed and then solidified (for example, Patent Document 1).

  In this manufacturing method, the die pad portion in the insulating substrate is 0.50 to 1.50 times the length and width of the rectangular light-emitting element to be die-bonded, whereby the surface of the die bond member is reflowed. Due to the self-alignment effect due to tension, the light emitting element is accurately arranged at the center of the die pad portion.

  In addition, by forming a narrow extension part extending outward from the die pad part integrally around the die pad part, one die bonding agent applied to the surface of the die pad part is provided. The part spreads on the surface of the narrow extension part, and by this spread, the rising height of the die bonding agent on the surface of the die pad part is lowered under the state where self-alignment by the die bonding agent is ensured. As a result, the floating height of the semiconductor chip from the die pad can be reduced, the unevenness of the height can be reduced, and the depth of penetration of the semiconductor chip with respect to the die bonding agent becomes shallow, resulting in an electrical short circuit in the semiconductor chip. And the semiconductor chip is a light-emitting diode chip. The amount of light emission from the light-emitting diode chip is disclosed that avoids a decrease.

JP 2003-264267 A

  However, if a narrow extension that extends outward from the die pad part is partially provided, a part of the die bonding agent can be expanded, but the die pad part becomes large and the light emitting device is downsized. Difficult to do.

  Furthermore, when the extension direction of the extension portion is adjacent to the wire bonding portion, there may be a problem that the die bonding agent spreads to the wire bonding portion and the power feeding portion. This may cause a problem of wire bonding failure.

  In particular, in recent years, there is a case where a plurality of light emitting elements are mounted in one package in the present situation that demand for miniaturization and high output for light emitting devices is increasing. In such a case, the above problem is It becomes a more serious problem.

  The present invention has been made in view of the above problems, and while accurately arranging the light emitting element in the die pad portion, the spread and wraparound of the die bonding agent to the wire bonding portion is suppressed, and the problem of poor bonding of the wire It is an object of the present invention to provide a light emitting device that is small and highly reliable.

  In order to achieve the above object, a semiconductor device according to the present invention includes a light emitting element having a metal film formed on a bottom, and a first metal on which the light emitting element is placed and disposed below the light emitting element. A member, a die-bonding member made of a metal that bonds the first metal member and the metal film of the light emitting element, at least one second metal member connected to the electrode of the light emitting element by a wire, and the first A first metal member and a support body on which the second metal member is disposed, and the first metal member has a polygonal shape formed in substantially the same size as the bottom surface of the light emitting element in a plan view. A die pad part, and a protruding part protruding from a side formed by the outer shape of the die pad part, the side over which the wire straddles is substantially straight, and the protruding direction of the protruding part and the connecting direction of the wire are approximately Characterized by being vertical

  In this light emitting device, the metal film preferably has a laminated film of Ag, Rh, and Au.

  The die bond member is preferably AuSn-based.

  Furthermore, it is preferable that the support is a submount that can be mounted on a substrate in a state where the light emitting element is mounted.

  According to the light emitting device of the present invention, it is possible to solve the problem of wire bonding failure by suppressing the spread and wraparound of the die bonding agent to the wire bonding portion while accurately arranging the light emitting element in the die pad portion. . As a result, a small and highly reliable light-emitting device can be provided.

  The best mode for carrying out the present invention will be described below. However, the form shown below illustrates the light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate.

  The light-emitting device according to the present embodiment includes a light-emitting element having a metal film formed on the bottom, a first metal member on which the light-emitting element is placed and disposed below the light-emitting element, and the first metal A die-bonding member made of a metal that bonds the member and the metal film of the light-emitting element; at least one second metal member connected to the electrode of the light-emitting element by a wire; the first metal member and the second metal member; The first metal member has a polygonal die pad portion formed in substantially the same size as the bottom surface of the light emitting element in a plan view, and the die pad portion of the die pad portion. A protruding portion protruding from a side formed by the outer shape, a side over which the wire extends is substantially straight, and a protruding direction of the protruding portion and a connecting direction of the wire are substantially vertical. Is.

  The structure of the light emitting device of the present invention will be described with reference to FIGS. 1 to 3 are views showing a main part of the light emitting device according to the present embodiment.

  A first metal member 103 and a second metal member 104 are arranged on the support 107, and the light emitting element 105 is fixed to the first metal member 104 with a die bond member made of metal. The electrode of the light emitting element and the second metal member 104 are connected by a wire 106 and are electrically connected.

  As shown in FIG. 2, the first metal member 103 on which the light emitting element 105 is placed includes a die pad portion 102 formed to be approximately the same size as the bottom surface of the light emitting element 105, and a side formed by the outer shape of the die pad portion 102. A protrusion 101 protruding from the bottom. On the die pad portion 102, a light emitting element having a metal film formed on the bottom is placed and fixed with a die bond member made of metal.

  The light-emitting element 105 is obtained by applying an appropriate amount of a die bond member to the die pad portion 102 formed on the support 107, placing the light-emitting element 105 having a metal film on the bottom, and melting it by heating. It is fixed by the method of solidifying. When the die bond member is melted, the die bond member mainly spreads along the first metal member to which the die bond member is applied.

  As described above, since the die bonding member spreads so that the light emitting element placed thereon moves away from the place where the die bonding member is placed, the die pad portion of the present embodiment is substantially the same size as the bottom portion of the light emitting element. Formed. By doing so, self-alignment due to the surface tension of the melted die bond member can be ensured, and the side formed by the outer shape of the die pad portion 102 and each side of the light emitting element in plan view (in other words, the side surface of the light emitting element) ) Can be arranged substantially in parallel.

  At this time, as described above, since the melted die bond member spreads along the first metal member, even if the die bond member is applied directly below the light emitting element, that is, only to the die pad portion 102, only the die pad portion 102 is applied. Instead, the melted die bond member spreads to the protruding portion 101. Since the die bond member is applied in an appropriate amount, when the amount is small, even if the protrusion 101 is formed, after the die bond member is melted and solidified, it is applied to the die pad portion 102 immediately below the light emitting element. Only placed. However, when a large amount of die bond members are applied due to variations in the amount of die bond member applied, the die bond member spreads or swells to the wire bond portion that is the peripheral portion of the light emitting element. In such a case, mass productivity decreases, which is not preferable. In the present embodiment, the location where the die bond member spreads and wraps around can be managed so as to be the protruding portion 101, so even if the die bond member spreads out, it does not interfere with the wire bond. Can lead.

  Further, in this case, when the die bond member is melted and fixed to the protrusion 101, a fillet 109 of the die bond member formed on the protrusion 101 is formed as shown in FIG. When the fillet 109 is formed, it can be confirmed from the outside that the light emitting element 105 and the first metal member on the support 107 are fixed, which is preferable. Furthermore, the amount of heat generated from the light emitting element has been increased due to the recent improvement in the output of the light emitting element. However, by forming the fillet 109, heat can be released from the fillet and heat dissipation can be improved. Can do.

  The protruding portion 101 is formed so as to protrude from the side formed by the outer shape of the die pad portion 102. Since it is necessary that the first metal member as a whole can ensure self-alignment due to the surface tension of the melted die bond member, at least one side formed by the outer shape of the die pad portion 102 is substantially straight. is there. (In other words, the protruding portion is not formed.) However, in this embodiment, there may be a minute protrusion that can be said to be a substantially straight line so as not to hinder wire bonding. Further, in the present embodiment, the protruding direction of the protruding portion 101 and the connecting direction of the wire 106 are substantially perpendicular.

  As the shape of the protruding portion, for example, as shown in FIG. 2A, it may be provided in a substantially square shape symmetrically on two opposite sides of the sides formed by the outer shape of the die pad portion 102, or as shown in FIG. 2B. Further, it may be provided point-symmetrically with respect to the center of the rectangular die pad portion 102, or may be formed in a substantially semicircular shape as shown in FIG. 2C. As shown in FIGS. 2A to 2C, the self-alignment effect can be more effective by preventing protrusions from being formed on half of the sides formed by the outer shape of the die pad portion 102.

  By forming in this way, there is no spread or wraparound of the die bond member on the side where the protruding portion is not formed. Therefore, by connecting the wire 106 to the second metal member 104 so as to straddle the upper part of this side, the wire The possibility of poor bonding can be avoided.

  In addition, since the clearance between the die pad portion and the second metal member can be reduced, the package can be reduced in size.

  In this light emitting device, the metal film preferably has a laminated film of Ag, Rh, and Au. In such a laminated film, the Rh film formed on the Ag metal film serves as a barrier layer for preventing diffusion of the die bond member, and Au serves as a film that wets the solder.

  Further, if the die bond member is AuSn, it is preferable because the melting point is low and the bonding strength is high.

  Further, it is preferable that the support 107 be a submount that can be mounted on a substrate in a state where the light emitting element 105 is mounted, because heat dissipation can be improved.

  The light-emitting device of the present invention is formed using the support on which the light-emitting element thus formed is mounted.

Below, each structural member of a light-emitting device is explained in full detail.
(Light emitting element 105)
The light emitting element may be a semiconductor light emitting element, and any element may be used as long as it is an element called a light emitting diode.

  The light-emitting element has a polygonal shape or a shape close thereto, and more preferably a quadrangle, a rectangle, a square, or a shape similar to these.

  Such a light emitting device may be a single-sided electrode in which a positive electrode and a negative electrode are formed on the same side with respect to the substrate, or a double-sided electrode in which the positive electrode or the negative electrode is formed on the back surface of the substrate. It may be.

(Metal film)
A metal film is formed on the entire bottom surface of the light emitting element (die bonding surface of the light emitting element). In particular, the metal film is preferably polygonal or formed on the entire back surface of the light emitting element. Thereby, since the wettability on the light emitting element side is increased, the self-alignment effect can be efficiently exhibited. The metal film preferably has a reflectance of 70% or more, more preferably 80% or more, with respect to light emitted from the light emitting element. When the electrode is formed on the back surface of the substrate, the metal film is preferably formed on the electrode. However, the electrode and / or the metal film may have both functions.

The metal film can be formed of, for example, a single layer film or a laminated film such as Al, Ag, Au, and Pd. As a method for forming the metal film, various known methods such as vapor deposition, sputtering, and plating can be used.

  In addition, it is preferable that the barrier layer which prevents the spreading | diffusion of the die-bonding member mentioned later is formed in the surface (namely, surface on the die-bonding side) of a metal film. The barrier layer can be formed of, for example, a single-layer film or a laminated film of a refractory metal such as Mo, W, or Rh. As a method for forming the barrier layer, various known methods such as vapor deposition, sputtering, and plating can be used.

(First metal member 103 and second metal member 104)
The materials of the first metal member 103 and the second metal member 104 are not limited. However, in order to effectively use the light emitted from the light emitting element, for example, about 70% or more with respect to the light emitted from the light emitting element, preferably A material having a reflectivity of about 80% or more, about 85% or more, or about 90% or more is suitable. The first metal member and the second metal member may be the same material or different materials. For example, the first metal member can be appropriately formed by forming the material with a good bondability with the metal film on the bottom surface of the light emitting element, and the second metal member with a material having a good bondability with the wire.

  In particular, in order to obtain a self-alignment effect, the first metal member is preferably a material having a contact angle with the die bond member of about 90 ° or less, about 80 ° or less, about 60 ° or less, and further about 45 ° or less. . In this specification, the contact angle was measured by a sessile drop method at a melting point of the bonding material +40 to 50 ° C. (“Wetting of graphite by molten magnesium”, “Light metal” Vol. 55, No. 7 (2005) p310). -314) refers to the value.

  A material that can be easily etched is preferable. For example, it can be formed of a single layer film or a laminated film of Al, Ag, Au, Pd or the like. When the metal member is formed in a film shape on the substrate, various known methods such as vapor deposition, sputtering, plating, etc. can be used.

(Die bond member 108)
As the die bond member, for example, a SnPb-based material, a SnAgCu-based material, an AuSn-based material, a SnZn-based material, a SuCu-based material, or the like can be preferably used. Among these, AuSn eutectic is preferable. Optionally, Bi, In or the like may be added to these for the purpose of improving wettability or solder cracking property.

(Wire 106)
As the wire 106, for example, a wire made of a metal such as a gold wire, a copper wire, a platinum wire, an aluminum wire, or an alloy thereof can be used.

(Support)
A 1st metal member and a 2nd metal member are arrange | positioned at a support body. The support itself may be a so-called package substrate mounted on a mounting substrate or the like of the light emitting device, or may be a submount mounted on the package substrate.

The material is preferably made of an appropriate material in order to ensure insulation. Specific examples include ceramics such as Al ₂ O ₃ and AlN, plastics such as high melting point nylon, and glass. Especially, it is suitable for the material that a contact angle with a die-bonding member exceeds 90 degrees, and it is more preferable that it is a material more than 100 degrees, 105 degrees, and 110 degrees. By selecting such a material, the alignment effect of the die bonding member at the time of die bonding of the light emitting element can be more remarkably exhibited.

  In addition, AlN is preferable for a light emitting element having a coefficient of thermal expansion substantially equal to the light emitting element, for example, a nitride semiconductor light emitting element. By using such a material, the influence of thermal stress generated between the support and the light emitting element can be reduced.

(Other parts)
(Sealing member)
In order to seal the light emitting element, a sealing member may be formed. The sealing member is formed of any material as long as it can seal the above-described light-emitting element, preferably integrally or in a lump, and can ensure insulation against the light-emitting element. May be. For example, any of YAG: Ce fluorescent substances and known fluorescent substances described in JP-A-2005-19646, JP-A-2005-8844 and the like can be used.

(Other parts)
The light emitting device of the present invention is provided as a part of the light emitting device or attached to the surface of the sealing member, for example, on the light emitting portion of the light emitting element (for example, above the light emitting element) for protecting the light emitting portion and the wire. A cover, an optical lens, or the like may be provided. At this time, when the bonding portion is a metal conductive pattern when these covers and lenses are bonded via an adhesive or the like, the package substrate is partially exposed or an insulating layer (for example, on the conductive pattern (for example, By providing an AlN layer, it is possible to bond firmly compared to the case of directly bonding to a metal conductive pattern.

  In order to efficiently extract light from the light emitting element, various components such as a reflection member, an antireflection member, and a light diffusion member may be provided. Further, a protective element for improving electrostatic withstand voltage may be provided.

  The light-emitting device of the present invention is formed as a surface-mount (SMD) light-emitting device in which a light-emitting element and a sealing resin are disposed in a recess of a package having a bottom surface and a wall portion surrounding the light-emitting element. Also good. The package may be formed of any material as long as it can protect the light emitting element, the sealing resin, and the like. Especially, it is preferable that it is a material which has insulation and light-shielding properties, such as a ceramic and milky white resin. Further, it is preferable to select a package having a small difference in thermal expansion coefficient with respect to the sealing resin or the like when affected by the heat generated from the light emitting element or the like. . The bottom surface and the wall of the package may be made of a material that is continuous with the support and the metal member, and a part of the metal member may be exposed to form an electrical connection or a heat dissipation path. A reflective material that reflects light from the light emitting element may be provided inside the package, or may be formed in a reflector shape for condensing light.

  Embodiments of the light emitting device according to the present invention will be described below in detail with reference to the drawings.

Example 1
As shown in FIG. 5, the light emitting device 500 of this embodiment includes a package substrate 511 made of AlN, a submount (support) 507 made of AlN placed on the package substrate via Ag paste, Similarly, a protective element 512 mounted via Ag paste is provided, and the electrodes 513 and 514 of the package substrate 511 and the electrodes of the submount 507 are connected by Au wires 515 and 516.

  FIG. 6 is a view of the submount 507 of this embodiment as viewed from above. A light emitting element 505 is mounted on the die pad portion of the submount 507, a protrusion 501 is formed so as to protrude from the die pad portion, and a wire 506 is straddled across a side different from the side where the protrusion 501 is formed. The electrode of the light emitting element 505 and the second metal member 504 are connected.

  This light emitting device can be manufactured as follows.

  First, a square light emitting element 505 having a length of 1,000 μm and a width of 1,000 μm is prepared. This light emitting element is made of a nitride semiconductor that emits blue light, and emits light having a wavelength of about 455 nm. Three positive and three negative electrodes are formed on the surface of the light emitting element. On the bottom surface, an Ag metal film, an Rh barrier film for preventing diffusion of the solder material, and an Au film that gets wet with the solder are laminated in this order on the entire surface by sputtering.

  Next, an AlN substrate having a length of 1.9 mm, a width of 4.9 mm, and a thickness of 1.0 mm is prepared as a submount. A Ti (1,000 Å) / Pt (2,000 Å) / Ag (10,000 Å) film is laminated on the upper surface of this submount by sputtering to form a first metal member and a second metal member 504. Form. At this time, when the sealing member is arranged on the submount by printing or the like, a convex alignment mark 510 used as a reference point is simultaneously formed.

  Subsequently, an appropriate amount of paste made of 78 wt% Au, Au—Su particles and flux is applied as a die bond member to the die pad portion, and the light emitting element 505 is placed thereon and temporarily fixed.

  Thereafter, in order to align the light emitting element with the die pad portion with high accuracy, the submount 507 on which the light emitting element 505 is temporarily fixed is passed through a reflow furnace at 315 ° C., and the flux as the paste solvent is volatilized. Is melted and further solidified, and adhesively bonded to the die pad portion of the first metal member.

  Thereafter, the flux is washed with a semi-aqueous detergent.

  Next, the positive and negative electrodes on the upper surface of the light emitting element and the second metal member 504 are connected by Au wires.

  Subsequently, as the light-transmitting sealing member 518, a silicone resin containing a fluorescent material is formed on the main light extraction surface and the side surface of the light-emitting element 505.

  Next, a method for producing the package substrate 611 will be described.

  An AlN substrate having a length of 14.0 mm, a width of 9.0 mm, and a thickness of 1.0 mm is prepared. A W film is formed on the upper surface of the substrate by a printing method, the W film is sintered, and then Ni—B / Ni—P / Au plating is performed, whereby an electrode of the package substrate 511 which is a conductive pattern. 513 and 514 are formed.

  The package substrate 611 and the submount 507 obtained in this way are bonded by Ag paste, and the electrodes are connected by Au wires 615 and 616 to conduct. In addition, a protective element 612 for improving electrostatic withstand voltage is bonded to the conductive pattern of the package substrate 611 with Ag paste, and connected to the light emitting element 505 in reverse parallel with an Au wire 517.

  The light emitting device 500 thus formed has a protruding portion 501 that protrudes from the die pad portion of the submount 507 on which the light emitting element 505 is mounted, and has a side that is different from the side on which the protruding portion 501 is formed. The wire 506 connects the electrode of the light emitting element 505 and the second metal member 504 so as to straddle, so that the die bonding agent spreads to the wire bonding portion while accurately arranging the light emitting element on the die pad portion. The wraparound can be suppressed and the problem of wire bonding failure can be solved. As a result, a small and highly reliable light-emitting device can be obtained.

Example 2
As shown in FIG. 7, the light-emitting device 700 of this example is a light-emitting device of Example 1, further comprising a resin cover 719 for protecting the light-emitting portion and the wires.

  It can be used for various light sources such as illumination light sources, various indicator light sources, in-vehicle light sources, display light sources, liquid crystal backlight light sources, traffic lights, in-vehicle components, and signboard channel letters.

It is a schematic plan view of the principal part in the light-emitting device of this invention. It is a top view for demonstrating the 1 metal member in the light-emitting device of this invention. It is a figure for demonstrating the principal part in the light-emitting device of this invention. It is a perspective view of the principal part of the light-emitting device of this invention. It is a perspective view of the light emitting device of the present invention. It is a schematic top view of the principal part in the light-emitting device of this invention. It is a perspective view of the light emitting device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101,501 Protrusion part 102 Die pad part 103 1st metal member 104,504 2nd metal member 105,505 Light emitting element 106,506,515,516,517 Wire 107 Support body 108 Die bond member 109 Fillet 500,700 Light emitting device 507 Submount 510 Alignment mark 511 Package substrate 512 Protection element 513, 514 Conductive pattern 518 Sealing resin 719 Cover

Claims (4)

A light emitting device having a metal film formed on the bottom;
A first metal member on which the light emitting element is mounted and disposed under the light emitting element;
A die bond member made of a metal that bonds the first metal member and the metal film of the light emitting element;
At least one second metal member connected to the electrode of the light emitting element by a wire;
A support body on which the first metal member and the second metal member are disposed;
The first metal member has a polygonal die pad portion formed in substantially the same size as the bottom surface of the light emitting element in a plan view, and a protruding portion protruding from a side formed by the outer shape of the die pad portion. ,
The side that the wire straddles is a straight line ,
The light emitting device according to claim 1, wherein a protruding direction of the protruding portion and a connecting direction of the wires are substantially perpendicular.   The light emitting device according to claim 1, wherein the metal film has a laminated film of Ag, Rh, and Au.   The light emitting device according to claim 1, wherein the die bond member is AuSn-based.   The light emitting device according to claim 1, wherein the support is a submount that can be mounted on a substrate in a state where the light emitting element is mounted.

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