JP4976982B2 - LED unit - Google Patents

Description

  The present invention relates to an LED unit in which a surface-mounted LED is mounted on a wiring board.

  Conventionally, in a surface-mounted LED including an LED chip and a package containing the LED chip, a heat radiating conductor is provided on the back side of the package in order to efficiently dissipate heat generated by the LED chip to the outside. Have been proposed (for example, Patent Documents 1 and 2).

  Here, in the surface-mounted LED described in Patent Document 1, an outer lead electrode constituting an external connection electrode protrudes from the side surface of the package, and is embedded in the center of the package and mounted with an LED chip. The heat sink (heat radiating core) constitutes the heat radiating conductor. Further, the surface-mounted LED described in Patent Document 2 is a metal member in which an external connection electrode is formed across the back and side surfaces of a package, and is embedded in the center of the package and mounted with an LED chip. Constitutes a heat radiating conductor.

By the way, when using the surface-mounted LED described above for applications that require a relatively large light output, such as general lighting, in order to improve the heat output of the surface-mounted LED and improve the light output, It is conceivable to construct an LED unit by mounting a plurality of surface-mounted LEDs on a single metal base printed wiring board. In such an LED unit, the external connection electrode of the surface-mounted LED is bonded to the wiring conductor pattern of the metal base printed wiring board via the first bonding portion made of solder, and the heat dissipation conductor portion is It is joined to the conductive pattern for heat dissipation of the metal base printed wiring board via a second joint made of solder. Here, in the metal base printed wiring board, an insulating resin layer is formed on a Cu metal plate, and each conductor pattern is formed on the insulating resin layer.
JP 2003-332634 (paragraphs [0028], [0041]-[0046], and FIG. 1) JP 2001-148514 A (paragraphs [0016]-[0027], [0058]-[0063] and FIGS. 1-4, 9-12)

  By the way, in the above-mentioned LED unit, the heat dissipation is improved in order to increase the output power by suppressing the increase in the junction temperature of the LED chip of the surface-mounted LED and increasing the input power. Since an insulating resin layer is interposed between the heat-dissipating conductor of the mounted LED and the metal plate of the metal-based printed wiring board, the heat resistance of the heat-dissipating path increases, making it difficult to increase the light output. It was.

  In addition, in the LED unit described above, when thermal stress due to a temperature cycle due to on / off of current is applied, stress is applied to the joint due to a difference in linear expansion coefficient between the surface-mounted LED package and the metal base printed wiring board. In some cases, cracks may occur in the joints, resulting in poor energization and reduced heat dissipation. Further, in the above LED unit, the second joint portion between the heat radiation conductor portion and the heat radiation conductor pattern of the metal base printed wiring board is located on the inner side of the outer peripheral line of the package in the projection view. After mounting on the wiring board, it is not possible to visually check the bonding state of the second bonding portion, and if a large facility such as an X-ray apparatus is not used, the bonding state of the second bonding portion may be checked. Since it was not possible, the joining situation of the 2nd joined part was not able to be checked easily.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide an LED unit that can improve light output and has high reliability with respect to a temperature cycle.

  The invention of claim 1 includes a heat transfer plate made of a first heat conductive material, a submount portion made of a second heat conductive material protruding on one surface side of the heat transfer plate, an insulating base A wiring board in which a wiring pattern is formed on one surface side of the material and a window hole in which the submount portion is spaced apart inwardly extends in the thickness direction and is disposed on the one surface side of the heat transfer plate And an external connection electrode provided on the package containing the LED chip is bonded to the wiring pattern on the one surface side of the wiring board via the first bonding portion made of the first bonding material and the back surface of the package A heat-dissipating conductor provided on the side and a surface-mounted LED joined to the submount via a second joint made of a second joining material, and between the heat transfer plate and the wiring board They are interposed and joined together, and the heat transfer plate, wiring board, and Characterized by comprising providing a stress relieving portion formed of a thermoplastic resin to relax the stress applied due to the difference in linear expansion coefficient between the cage respectively to each respective joint.

  According to this invention, the submount portion made of the second heat conductive material protruding on the one surface side of the heat transfer plate made of the first heat conductive material, and the one surface side of the insulating base material A wiring board on which the wiring pattern is formed and a window hole in which the submount portion is spaced apart on the inside is provided in the thickness direction and disposed on the one surface side of the heat transfer plate; In the type LED, an external connection electrode provided on a package containing an LED chip is bonded to the wiring pattern on the one surface side of the wiring board via a first bonding portion made of a first bonding material and Since the heat dissipating conductor provided on the back side is joined to the submount via the second joint made of the second joining material, the heat generated by the LED chip is provided on the back side of the package. From the heat dissipation conductor The heat is dissipated through the submount portion formed of the heat conductive material 2 and the heat transfer plate formed of the first heat conductive material, and the insulating resin layer is interposed in the heat dissipation path as in the past. Compared to the case, since the thermal resistance of the heat dissipation path can be reduced, the temperature rise of the LED chip is suppressed, and the light output can be improved. Further, the inner peripheral surface of the window hole formed in the wiring board and the submount part are separated from each other, and both are joined between the heat transfer plate and the wiring board, and the heat transfer plate, the wiring board, and Since there is a stress relaxation part made of thermoplastic resin that relieves stress acting on each joint due to the difference in linear expansion coefficient with each package, the heat transfer plate and wiring board are made of thermosetting resin. Compared with the case where it joins, the stress concerning each joined part resulting from a temperature cycle can be relieved, and the reliability with respect to a temperature cycle can be improved.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the second thermally conductive material is an electrically insulating material.

  According to the present invention, the surface-mounted LED and the heat transfer plate can be electrically insulated by the submount portion. For example, a metal member is arranged on the other surface side of the heat transfer plate. In this case, it is not always necessary to dispose a member having electrical insulation between the heat transfer plate and the metal member, and the metal disposed on the other surface side of the heat transfer plate and the heat transfer plate. Even in the case where an organic green sheet having high thermal conductivity and electrical insulation is interposed between the components, it is possible to reduce the level of electrical insulation of the organic green sheet and to use an inexpensive one. It becomes.

  According to a third aspect of the present invention, in the first aspect of the invention, the first thermal conductive material and the second thermal conductive material are the same material, and the submount portion is continuous from the heat transfer plate. It is characterized by projecting integrally.

  According to the present invention, the number of parts can be reduced, manufacturing becomes easy and cost can be reduced.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the submount portion is formed so as to cross the package in a plan view.

  According to this invention, since the submount portion is formed so as to cross the package in plan view, the heat dissipating conductor portion provided on the back surface side of the package and the submount portion Part of the two joints can be formed to the outside of the outer peripheral line of the package in plan view, and the joining state of the second joint can be easily confirmed visually.

  According to the first aspect of the invention, the light output can be improved and the reliability with respect to the temperature cycle can be enhanced.

(Embodiment 1)
As shown in FIGS. 1 and 2, the LED unit A of the present embodiment projects to the heat transfer plate 2 made of the first heat conductive material (for example, Cu) and one surface side of the heat transfer plate 2. The submount part 3 made of the second thermally conductive material (for example, AlN) provided, and the wiring patterns 42 and 42 are formed on one surface side of the insulating base material 41, while the submount part 3 is on the inner side. A window hole 43 that is spaced apart from each other is provided in the thickness direction so as to penetrate the wiring board 4 that is disposed on the one surface side of the heat transfer plate 2 and the package 12 that houses the LED chip 11. The connection electrodes 13 and 13 are joined to the wiring patterns 42 and 42 on the one surface side of the wiring board 4 through first joining portions 6 and 6 made of a first joining material (for example, solder). Heat dissipating conductor provided on the back side of the package 12 15 includes a surface mount type LED 1 bonded to the submount 3 via a second bonding portion 7 made of a second bonding material (for example, solder), and includes a heat transfer plate 2 and a wiring substrate 4. Heat that relaxes the stress acting on each joint 6, 6, 7 due to the difference in linear expansion coefficient between the heat transfer plate 2, the wiring substrate 4, and the package 12. A stress relaxation portion 8 made of a plastic resin is provided.

  When the LED unit A of this embodiment is used as a light source of a lighting fixture, for example, as shown in FIG. 1, it contains a filler made of a filler such as silica or alumina and has a low viscosity during heating, and the flow during the heating Highly conductive epoxy resin sheet (for example, an organic green sheet such as an epoxy resin sheet highly filled with fused silica) 110 is used to make a metal member (for example, a metal plate or metal) made of a metal having high thermal conductivity such as Al. And the heat transfer plate 2 may be joined and thermally coupled. Here, the organic green sheet 110 described above has an electrical insulation property, a high thermal conductivity, a high fluidity during heating, and a high adhesion to an uneven surface. Joining via the green sheet 110 (After the organic green sheet 110 is interposed between the heat transfer plate 2 and the metal member 100, the organic green sheet 110 is heated to thereby heat the heat transfer plate 2 and the metal member 100. Can be prevented from generating gaps between the organic green sheet 110 and the heat transfer plate 2 and the metal member 100, and an increase in thermal resistance and variation due to insufficient adhesion can be prevented. As in the prior art, a surface-mounted LED is mounted on a metal-based printed wiring board, and between the metal-based printed wiring board and the metal member, such as Sarcon (registered trademark). Compared to the case of sandwiching a rubber sheet-like heat dissipation sheet or the like, the thermal resistance from the LED chip 11 to the metal member 100 can be reduced, heat dissipation is improved, and variation in the thermal resistance is reduced. Therefore, the input power can be increased and the optical output can be increased.

  Moreover, when using LED unit A of this embodiment as a light source of a lighting fixture, the several LED unit A is mounted with respect to the metal members 100, and the connection relation of each LED unit A is prescribed | regulated. The circuit board 200 in which the wiring pattern 202 is formed on one surface side of the insulating base material 201 and the opening window 203 in which the LED unit A is spaced apart from the inside is penetrated is described above with respect to the metal member 100. What is necessary is just to join by the organic green sheet 110. The connection relationship of the plurality of LED units A is not particularly limited. For example, the LED units A may be connected in series, connected in parallel, or a combination of series connection and parallel connection. Also good. Moreover, as a material of the insulating base material 201 of the circuit board 200, for example, a glass epoxy resin such as FR4 may be adopted, but not limited to a glass epoxy resin, for example, a polyimide resin or a phenol resin may be used. .

  On the other hand, in the LED unit A, each external connection electrode portion 42 b in the wiring pattern 42 of the wiring board 4 is electrically connected to the circuit pattern 202 of the circuit board 200 via the jumper pins 220. Here, one end of the jumper pin 220 is joined to the external connection electrode portion 43b via the third joint 9 made of solder, and the other end is joined to the circuit pattern 202 of the circuit board 200 by solder. The intermediate portion is bent in a U shape, and the stress generated in each of the third joint portion 9 and the second joint portion 230 due to the temperature cycle is generated. Since it can ease, the connection reliability between each LED unit A and the circuit board 200 can be improved.

  Hereinafter, each component of the LED unit A will be described in detail.

  The surface-mounted LED 1 includes the above-described LED chip 11, the above-described package 12, and a phosphor that emits light of a color different from the emission color of the LED chip 11 when excited by light emitted from the LED chip 11. And a color conversion member 16 formed of the translucent material.

  The surface-mounted LED 1 described above uses a GaN-based blue LED chip that emits blue light as the LED chip 11 and is excited and broadened by the blue light emitted from the LED chip 11 as a phosphor of the color conversion member 16. The yellow light emitted from the LED chip 11 and transmitted through the color conversion member 16 and the yellow light emitted from the yellow phosphor of the color conversion member 16 are used. Are emitted as light distribution diffused from the light exit surface of the color conversion member 16, and white light can be obtained. In the surface-mounted LED 1 described above, a blue LED chip is used as the LED chip 11 and one type of yellow phosphor is used as the phosphor in the color conversion member 16 so that white light is obtained as mixed color light. However, the emission color of the phosphor may be appropriately selected according to the desired mixed color light, and is not limited to one type of yellow phosphor, for example, using two types of yellow phosphors having different emission peak wavelengths. Alternatively, a red phosphor and a green phosphor may be employed. Further, the emission color of the LED chip 11 is not limited to blue light. Moreover, although the silicone resin is employ | adopted as a translucent material of the color conversion member 16, it is not restricted to a silicone resin, For example, an acrylic resin, glass, an organic component and an inorganic component are mixed by the nm level or a molecular level. Alternatively, a combined organic / inorganic hybrid material may be employed.

  Each LED (not shown) is formed on one surface side (upper surface side in FIG. 1) of the LED chip 11 described above, and the package 12 is provided with a storage recess 12a for storing the LED chip 11 on one surface. Two conductor patterns 14 and 14 are formed, which are electrically connected to the respective electrodes of the LED chip 11 via bonding wires 17 and 17, and the respective conductor patterns 14 and 14 are packaged. 12 are extended to and electrically connected to the external connection electrodes 13 and 13 formed across the side surface and the other surface (back surface). The package 12 has a rectangular outer peripheral shape in plan view.

  The package 12 is provided with a heat radiation conductor 15 made of a conductive material (for example, Cu) on the other surface side. The heat radiation conductor 15 is a mount portion on which the LED chip 11 is mounted. 15b is projected continuously from the center. Here, the LED chip 11 is joined to the mount portion 15b of the heat radiation conductor portion 15 by solder (for example, AuSn solder). Further, the heat radiating conductor 15 projects from the plane including the other surface of the package 12 beyond the external connection electrodes 13 and 13.

  In the surface-mounted LED 1, the outer peripheral line of the heat radiation conductor 15 in the projection view is located outside the outer peripheral line of the LED chip 11. In short, the LED chip 11 is disposed in the projection region of the heat radiating conductor 15. Therefore, since the heat generated in the LED chip 11 is transferred to the heat radiation conductor 15 wider than the LED chip 11 and radiated, the temperature rise of the LED chip 11 is suppressed, the light output can be improved, and the lifetime is shortened. And improve reliability. The LED chip 11 has a function to relieve stress acting on the LED chip 11 due to a difference in linear expansion coefficient between the LED chip 11 and the heat radiating conductor portion 15 and heat generated in the LED chip 11 in the mount portion 15b. You may make it mount in the mount part 15b via the submount member which has the heat-conduction function which transfers heat to the range wider than the chip size of the chip | tip 11.

  The material of the above-described package 12 is not limited to ceramic such as alumina, but may be a heat-resistant resin such as a highly insulating glass epoxy resin or liquid crystal polymer. Moreover, the material of the heat radiating conductor 15 is not limited to Cu, and may be CuW, for example. Further, the heat dissipating conductor portion 15 is not necessarily provided with the mount portion 15b, and a die pad portion for die-bonding the LED chip 11 may be provided on the inner bottom surface of the housing recess 12a of the package 12.

  The storage recess 12a in the package 12 is opened in a circular shape, and the opening area gradually increases as the distance from the inner bottom surface increases, and a step 12b is formed in the vicinity of the opening surface of the storage recess 12a. Here, the surface-mounted LED 1 is formed by sealing the peripheral portion of the sheet-like color conversion member 16 having a circular outer peripheral shape in plan view to the step portion 12b using an adhesive. The storage recess 12 a is closed by the color conversion member 16. The space surrounded by the package 12 and the color conversion member 16 is sealed with a light-transmitting sealing material (for example, silicone resin, glass, etc.) that seals the LED chip 11 and the bonding wires 17 and 17. Although the stop (not shown) is substantial, the space may be an air atmosphere, an inert gas atmosphere, or a vacuum atmosphere, and the orientation of light from the LED chip 11 is controlled or the light extraction efficiency is appropriately increased. The optical member may be accommodated. The color conversion member 16 is not limited to a sheet shape, and may be a dome shape, for example.

  The heat transfer plate 2 made of the first heat conductive material is formed in a rectangular plate shape, and the wiring substrate 4 is joined to the one surface side via a stress relaxation portion 8 made of a thermoplastic resin. Yes. Here, as the thermoplastic resin, for example, APAS (trade name of Sumitomo 3M Limited) may be used. In the present embodiment, Cu is employed as the first thermal conductive material, but not limited to Cu, for example, Al may be employed.

  The wiring board 4 is formed in a rectangular plate shape like the heat transfer plate 2, and a rectangular window hole 43 in which the above-described submount portion 4 is spaced apart from the inside is formed in the central portion. .

  The wiring board 4 described above is provided with a pair of wiring patterns 42, 42 for feeding power to the surface-mounted LED 1 on one surface side of an insulating base 41 made of polyimide film, and each wiring pattern 42, 42 and A protective layer 44 made of a white resist (resin) covering a portion where the wiring patterns 42 and 42 are not formed in the insulating base material 41 is laminated. Here, the protective layer 44 is an electrode portion where the land portions 42a and 42a to which the external connection electrodes 13 and 13 of the surface mount LED 1 are bonded and the one end portion of the jumper pin 220 are bonded in the wiring patterns 42 and 42, respectively. Patterning is performed so that each of 42b and 42b is exposed. Moreover, the wiring patterns 42 and 42 of the wiring board 4 are formed of Cu. In addition, as a material of the insulating base material 41, FR4, FR5, paper phenol, or the like may be employed.

  As the second thermally conductive material that is the material of the submount part 3, AlN having electrical insulation is adopted, and the heat dissipating conductor part 15 and the submount part 3 of the surface mount LED 1 are made of AuSn. Metal layers 31 and 19 made of Au are previously formed on the bonding surfaces of the submount portion 3 and the heat radiation conductor portion 15 respectively. The material for joining the heat-radiating conductor 15 and the submount 3 is not limited to AuSn, and may be joined using, for example, solder such as AuSn, SnPb, SnAgCu, or silver paste.

  Further, the submount 3 and the heat transfer plate 2 are bonded via a fourth bonding portion 34 made of AuSn, and a metal made of Au in advance on the bonding surface of each of the submount 3 and the heat transfer plate 2. Layers 32 and 22 are formed. The material for joining the submount unit 3 and the heat transfer plate 2 is not limited to AuSn, and for example, solder such as AuSn, SnPb, SnAgCu, silver paste, or the like may be used.

  The above-described submount portion 3 has a heat conduction function for conducting heat generated in the LED chip 11 of the surface-mounted LED 1, and the surface area of the submount portion 3 on the side of the heat dissipating conductor portion 15 is radiated. It is larger than the area of the surface on the submount portion 3 side in the conductor portion 15 for use. In short, the submount portion 3 is formed in a rectangular shape having a size larger than the planar size of the heat dissipating conductor portion 15 of the surface mount LED 1, and the metal layer 31 on the heat dissipating conductor portion 15 side in the submount portion 3 is The plane size of the submount 3 is slightly smaller than the plane size. Here, in the LED unit A of the present embodiment, the submount 3 is formed so as to cross the package 12 of the surface-mounted LED 1 in plan view, and is used for heat dissipation provided on the other surface side of the package 12. Part of the second joint 7 between the conductor 15 and the submount 3 can be formed to the outside of the outer peripheral line of the package 12 in a plan view, and the solder fillet of the second joint 7 can be formed. Since the presence / absence can be visually confirmed, the joining state of the second joint 7 can be easily confirmed visually. For the first joints 6 and 6 between the external connection electrodes 13 and 13 and the wiring patterns 42 and 42, the external connection electrodes 13 and 13 straddle the other surface (back surface) and the side surface of the package 12. Since the presence / absence of the solder fillet can be visually confirmed, the joining state of the first joining portions 6 and 6 can be easily confirmed visually.

  The second heat conductive material that is the material of the submount portion 3 is not limited to AlN, and may be the same material as the first heat conductive material (for example, Cu) that is the material of the heat transfer plate 2. In this case, by providing the submount portion 3 continuously and integrally projecting from the heat transfer plate 2, the number of parts can be reduced, manufacturing becomes easy and cost can be reduced. However, in this case, it is more desirable to provide the organic green sheet 110 in order to electrically insulate the heat transfer plate 2 and the metal member 100.

  In the LED unit A of the present embodiment described above, the submount portion 3 made of the second heat conductive material protruding from the one surface side of the heat transfer plate 2 made of the first heat conductive material, Wiring patterns 42 and 42 are formed on the one surface side of the insulating base material 41 and a window hole 43 in which the submount portion 3 is spaced apart from the inside is provided in the thickness direction so as to penetrate the heat transfer plate 2. The external connection electrodes 13, 13 provided on the package 12 containing the LED chip 11 in the surface-mounted LED 1 are provided on the one surface side of the wiring substrate 4. The wiring patterns 42 and 42 are joined and electrically connected to each other via the first joining portions 6 and 6 made of a first joining material (solder or the like), and on the other surface side (back side) of the package 12. Provided heat dissipation conductor 5 is bonded to the submount 3 via a second bonding portion 7 made of a second bonding material (solder or the like), so that heat generated in the LED chip 11 is provided on the back side of the package 12. Heat is dissipated from the heat dissipating conductor 15 through the submount 3 and the heat transfer plate 2, and the heat resistance of the heat dissipating path can be reduced as compared with the conventional case where an insulating resin layer is interposed in the heat dissipating path. Therefore, the temperature rise of the LED chip 11 is suppressed, and the light output can be improved. Note that the same material is preferably used for the first bonding material and the second bonding material.

  Further, in the LED unit A of the present embodiment, the inner peripheral surface of the window hole 43 formed in the wiring board 4 and the submount part 3 are separated from each other, and between the heat transfer plate 2 and the wiring board 4, A stress made of a thermoplastic resin that joins both and alleviates the stress acting on each joint 6, 6, 7 due to the difference in linear expansion coefficient between the heat transfer plate 2 and each of the wiring board 4 and the package 3. Since the relaxing part 8 is interposed, compared to the case where the heat transfer plate 2 and the wiring board 4 are joined by the thermosetting resin, the joints 6, 6 and 7 are caused by the temperature cycle. The stress can be relaxed and the reliability with respect to the temperature cycle can be improved.

  Further, in the LED unit A of this embodiment, since the submount portion 3 is formed of a material having thermal conductivity and electrical insulation, the surface mount type LED 1 and the heat transfer plate 2 are heated by the submount portion 3. For example, when the metal member 100 is disposed on the other surface side of the heat transfer plate 2, the heat transfer plate 2 and the metal member 100 can be connected to each other. For example, as described above, the heat transfer plate 2 and the metal member 100 disposed on the other surface side of the heat transfer plate 2 are not necessarily provided. Even when an organic green sheet 110 having high thermal conductivity and electrical insulation is interposed, it is possible to reduce the level of electrical insulation (required performance) of the organic green sheet 110 and to use an inexpensive one. Possible That.

  By the way, as shown in FIG. 2, the LED unit A of the present embodiment has rounded corners by forming chamfered portions at four corners in plan view of the wiring board 4, but chamfered portions (see FIG. 2, the curvature radii of the remaining two chamfers (upper left and lower right chamfers in FIG. 2) are increased, and the direction in which the pair of external connection electrodes 13 and 13 are arranged side by side is increased. The land portions 42a and 42a are arranged so as to coincide with the juxtaposed direction of the pair of electrode portions 42b and 42b of the wiring board 4, but the arrangement of the land portions 42a and 42a is not particularly limited. As shown in FIG. 3 (a), the parallel arrangement direction of the pair of land portions 42a and 42a may be arranged at an angle of approximately 45 degrees with the parallel arrangement direction of the pair of electrode portions 42b and 42b. As shown in Figure (b) The parallel arrangement direction of the pair of land portions 42a and 42a may be arranged to form an angle of approximately 90 degrees with the parallel arrangement direction of the pair of electrode portions 42b and 42b, as shown in FIG. The parallel arrangement direction of the pair of land portions 42a and 42a may be arranged so as to form an angle of approximately 60 degrees with the parallel arrangement direction of the pair of electrode portions 42b and 42b.

(Embodiment 2)
The basic configuration of the LED unit A of the present embodiment is substantially the same as that of the first embodiment. As shown in FIGS. 4 and 5, a plurality of (four in the illustrated example) surface-mounted LEDs 1 are provided on the wiring board 4. Is mounted and the plurality of surface-mounted LEDs 1 are connected in series. In short, the wiring pattern 42 is formed on the wiring substrate 4 so that a plurality of surface-mounted LEDs 1 are connected in series. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  Therefore, in the LED unit A of the present embodiment, when used as a light source such as a lighting fixture, the circuit board 200 described in the first embodiment is not necessary, so that the cost can be reduced and the reliability can be improved. Is possible.

  In addition, the structure of the surface-mounted LED 1 in each of the above embodiments is not particularly limited, and the structure and number of the LED chips 11 and the mounting form of the LED chips 11 are not particularly limited. When the LED chip 11 having electrodes formed on both surfaces in the thickness direction is used and the LED chip 11 is mounted on the mount portion 15b of the heat dissipation conductor portion 15, the two external connection electrodes 13, 13 are provided. One of them and the heat-dissipating conductor portion 15 may be formed in a continuous and integrated manner or connected by wiring such as a bonding wire to form an electrically connected structure.

1 is a schematic cross-sectional view showing a first embodiment. It is a schematic plan view which shows the same as the above. It is explanatory drawing of the other structural example same as the above. FIG. 6 is a schematic cross-sectional view showing a second embodiment. It is a schematic plan view which shows the same as the above.

Explanation of symbols

A LED unit 1 Surface mount type LED
2 Heat Transfer Plate 3 Submount 4 Wiring Board 6 First Joint 7 Second Joint 8 Stress Relieving Part 11 LED Chip 12 Package 13 External Connection Electrode 15 Heat Dissipating Conductor 41 Insulating Substrate 42 Wiring Pattern 43 Window hole

Claims (4)

  A heat transfer plate made of a first heat conductive material, a submount portion made of a second heat conductive material protruding on one surface side of the heat transfer plate, and a wiring on one surface side of an insulating substrate A window hole in which a pattern is formed and a submount portion is spaced apart inwardly extends in the thickness direction and accommodates a wiring board arranged on the one surface side of the heat transfer plate and an LED chip. An external connection electrode provided on the package is bonded to the wiring pattern on the one surface side of the wiring board via the first bonding portion made of the first bonding material and is provided on the back surface side of the package. The conductor portion includes a surface mount type LED bonded to the submount portion via the second bonding portion made of the second bonding material, and is interposed between the heat transfer plate and the wiring board to bond the two. And each of the heat transfer plate, the wiring board and the package LED unit, characterized by comprising providing a stress relieving portion formed of a thermoplastic resin to relax the stress applied due to the difference in linear expansion coefficient between each respective junction.   2. The LED unit according to claim 1, wherein the second heat conductive material is an electrically insulating material.   The first heat conductive material and the second heat conductive material are the same material, and the submount portion protrudes continuously and integrally from the heat transfer plate. The LED unit according to 1.   4. The LED unit according to claim 1, wherein the submount portion is formed to cross the package in a plan view. 5.

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