TWI556480B - High thermal conductivity light emitting diodes - Google Patents

Description

High thermal conductivity LED

The invention relates to a light-emitting diode, in particular to a high-heat-conducting light-emitting diode.

Referring to FIG. 1 , a conventional light-emitting diode 1 is exemplified by a horizontal light-emitting diode, and mainly includes an epitaxial substrate 11 , a light-emitting unit 12 disposed on the epi-crystal substrate 11 , and a two-electrode unit 13 .

The light emitting unit 12 includes an n-type gallium nitride (n-GaN) layer 121 formed on a surface of the epitaxial substrate, and a multiple quantum covered on a surface of the n-type gallium nitride (n-GaN) layer 121. A layer (MQW) 122, and a p-type gallium nitride (p-GaN) layer covering the surface of the multiple quantum layer (MQW) 122. The electrode unit 13 includes a top electrode provided with the p-type gallium nitride (p-GaN) layer, and a bottom electrode provided with the n-type gallium nitride layer. When a current is applied from the electrode unit 13, the complex holes of the p-type gallium nitride (n-GaN) layer 123 and the complex electrons of the n-type gallium nitride (n-GaN) layer 121 are driven. The quantum layer (MQW) 122 combines to emit light. However, since the light-emitting unit 12 generates a large amount of thermal energy when it emits light, and the thermal conductivity of the sapphire substrate 11 is low (about 40 W/m*K), the heat dissipation effect is poor, and the light-emitting diode is lowered. The luminous efficiency of the whole body 1.

In order to solve the problem of heat dissipation of the sapphire substrate, such as the US Patent No. 8,809,898 B2, the invention discloses a method for manufacturing a vertical light-emitting diode, which mainly uses a substrate transfer method to convert the sapphire substrate into a heat dissipation property. Metal substrate to improve heat dissipation efficiency. However, the process of transferring the substrate makes the process more complicated, and the sapphire substrate must be removed by laser lift-off, which also increases the manufacturing cost; and the replaced metal substrate also adds extra weight.

It can be seen from the above description how to solve the heat dissipation problem of the light-emitting diode to improve the luminous efficiency, and at the same time avoiding the use of the metal substrate to reduce the weight and the manufacturing cost is a problem to be solved by those skilled in the art.

Accordingly, it is an object of the present invention to provide a highly thermally conductive light emitting diode.

Therefore, the high thermal conductivity light emitting diode of the present invention comprises: a heat conducting substrate, a light emitting unit, and an electrode unit.

The thermally conductive substrate comprises a plate body and a plurality of thermally conductive fibers dispersed in the plate body. The plate body has a base surface and a bottom surface opposite to the base surface. At least a portion of the thermally conductive fibers are exposed to the outside of the board.

The light emitting unit is disposed on a base surface of the board body.

The electrode unit is electrically connected to the light emitting unit for providing electrical energy to cause the light emitting unit to emit light.

The effect of the invention is that the conduction guide of the thermally conductive substrate The heat fiber guides the thermal energy generated when the light emitting unit emits light away from the light emitting unit to improve luminous efficiency.

2‧‧‧thermal substrate

21‧‧‧ board body

211‧‧‧ base

212‧‧‧ bottom

213‧‧‧ holes

214‧‧‧Support block

22‧‧‧ Thermal Conductive Fiber

3‧‧‧Lighting unit

31‧‧‧First type semiconductor layer

32‧‧‧ active layer

33‧‧‧Second type semiconductor layer

4‧‧‧Electrode unit

41‧‧‧ bottom electrode

42‧‧‧ top electrode

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a schematic diagram illustrating a conventional light emitting diode; FIG. 2 is a schematic view showing the high thermal conductivity of the present invention. A first embodiment of the diode; FIG. 3 is a perspective view showing the arrangement of the plurality of thermally conductive fibers in the first embodiment; FIG. 4 is a perspective view showing the heat conducting fibers. Another arrangement in the body of the board; FIG. 5 is a schematic view showing a vertical conduction state of the first embodiment; FIG. 6 is a schematic view showing another aspect of the thermally conductive substrate; A schematic view illustrating the plate body of the second embodiment.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 2 and FIG. 3 and FIG. 4, a first embodiment of the high thermal conductivity LED of the present invention comprises a thermally conductive substrate 2, a light emitting unit 3, and an electrode unit 4.

The heat conductive substrate 2 includes a plate body 21 and a plurality of dispersed therein The heat conducting fiber 22 of the plate body 21. The board body 21 has a base surface 211 and a bottom surface 212 opposite to the base surface 211. The constituent material of the plate body 21 is selected from a metal, an alloy metal, or a polymer, and at least a portion of the heat conductive fibers 22 are exposed outside the plate body 21.

The heat conducting fibers 22 are selected from a thermal conductivity of not less than 380 W/m. The fiber of K, the heat conducting fiber 22 suitable for the first embodiment may be selected from a thermal conductivity of 380 to 2000 W/m. K metal fiber, high thermal conductivity carbon fiber, or graphitized vapor deposited carbon fiber (Graphitized VGCF).

In detail, the heat conducting fibers 22 may be distributed to the board body 21 in a staggered manner as shown in FIG. 3 (the board body 21 is represented by an imaginary line in FIG. 3), or as shown in FIG. Extending along a vertical direction Z substantially perpendicular to the first type semiconductor layer 31. Wherein, when the heat conducting fibers 22 are stacked in a vertical direction Z in a staggered manner (as shown in FIG. 3), the heat conducting fibers 22 are arranged in the XY plane direction to have an optimum heat conduction effect; The thermally conductive fibers 22 extend in the vertical direction Z, and the thermally conductive substrate 2 has excellent thermal conductivity in the vertical direction Z. Preferably, the thermally conductive substrate 2 has a thermal conductivity of not less than 300 W/m ‧ in the direction in which the thermally conductive fibers 22 are arranged.

More specifically, the heat-conducting fibers 22 can be exposed from the outside of the board body 21 to increase the heat dissipation of the heat-conducting substrate 2. Preferably, the heat-conducting fibers 22 can be respectively The base surface 211 and the bottom surface 212 of the board body 21 are exposed to the outside from the base surface 211 and the bottom surface 212 of the board body 21 at the same time. When the heat conducting fibers 22 are from the board body 21 When the base surface 211 is exposed, the light-emitting unit 3 can directly contact the heat-conducting fibers 22 to accelerate the thermal energy generated by the light-emitting unit 3 to the heat-conductive substrate 2; when the heat-conducting fibers 22 are from the plate body 21 When the bottom surface 212 is exposed, the efficiency of guiding the thermal energy from the heat conducting substrate 2 away from the light emitting unit 3 and dissipating to the outside is improved; more preferably, the heat conducting fibers 22 can also be simultaneously from the base surface 211 of the board body 21 When the bottom surface 212 is exposed, the heat conduction and heat dissipation effects can be further enhanced. In the present embodiment, the heat conducting fibers 22 are arranged in a plurality of stacked layers on the board body 21 as shown in FIG. 3, and are exposed from the base surface 211 and the bottom surface 212 of the board body 21, respectively. To explain.

The light emitting unit 3 is disposed on the base surface 211 of the board body 21 and includes a first type semiconductor layer 31 disposed on the heat conductive substrate 2 and an active layer 32 partially disposed on the first type semiconductor layer 31. And a second type semiconductor layer 33 on the active layer 32 is covered. The electrode unit 4 has a bottom electrode 41 formed on one surface of the first type semiconductor layer 31, and a top electrode 42 formed on one surface of the second type semiconductor layer 33. It can be seen from the above structure that the first embodiment has a horizontal conduction state as shown in FIG. Since the structure of the light-emitting diode and the selection of related materials are well known in the art and are not the focus of the present technology, they will not be further described. In the first embodiment, the first type semiconductor layer 31, the active layer 32, the second type semiconductor layer 33, and the electrode unit 4 are respectively an n-type gallium nitride layer, a multiple quantum well layer, and p A type of gallium nitride layer, and gold as an example.

Referring to FIGS. 4 and 5, when the number of the heat conducting fibers 22 in the heat conducting substrate 2 is sufficient, the heat conducting substrate 2 can also be used as a conductive object. Therefore, the heat conducting substrate 2 having heat conduction and conductive properties can also be directly disposed. to Under the light-emitting unit 3, a light-emitting diode having a vertical conduction state is obtained. It should be noted that the more the content of the heat-conducting fibers 22 can improve the conductivity, however, the excessive heat-conducting fibers 22 reduce the coating property of the plate body 21 with respect to the heat-conducting fibers 22, and are not easy to form. Preferably, the volume of the thermally conductive fibers 22 in the thermally conductive substrate 2 is between 10 and 60%. In detail, if the material of the plate body 21 is epoxy, the volume of the heat-conducting fibers 22 is between 10% and 60%, and preferably, the volume of the heat-conducting fibers 22 is between 30%. % to 60%; if the material of the plate body 21 is aluminum, the heat conductive fibers 22 have a volume percentage of 10% to 35%. More specifically, when the material of the plate body 21 is epoxy, and the volume of the thermally conductive fibers 22 is 50%, the resistivity of the thermally conductive substrate 2 can reach 0.0011 Ω ‧ cm.

When the power is supplied from the electrode unit 4 to cause the light-emitting unit 3 to operate, especially for the high-power light-emitting diode, since the heat-conducting fiber 22 of the heat-conductive substrate 2 directly contacts the light-emitting unit 3, the light-emitting unit 3 is in the light-emitting process. The large amount of thermal energy generated in the light-emitting substrate 2 can be guided away from the light-emitting unit 3 by the heat-conducting fiber 22 of the heat-conducting substrate 2; and the heat energy can be further transmitted to the outside by the heat-conducting fiber 22 exposed outside the bottom surface 212, and has a pole Good cooling effect. In addition, the heat-conducting fibers 22 exposed on the board body 21 and not covered by the board body 21 may be bonded to each other by carbon particles, thereby maintaining a complete heat conduction path and avoiding the heat conductive fibers or The problem of component contamination caused by the falling of particles.

In addition, it is to be noted that, in order to improve the heat dissipation of the thermally conductive substrate 2, the plate body 21 may further have other different hollows. The heat-conducting fiber 22 can be exposed from other positions of the board body 21 to increase the contact area of the heat-conducting fiber 22 with the board body 21 or the external contact area, thereby improving the heat-conductive substrate 2 as a whole. Thermal and heat dissipation.

The above-mentioned heat-conducting fibers 22 can be exposed to the outer periphery of each of the crystal grains when the light-emitting diodes are subjected to die dicing. Alternatively, the partial structure of the board body 21 may be removed by laser, and the heat conducting fibers 22 may be exposed to the outside without particular limitation. For example, referring to FIGS. 5 and 6, a portion of the structure of the board body 21 may be removed by laser, so that the board body 21 is formed with a hollow structure having a plurality of supporting blocks 214 spaced apart from each other, such that the heat conducting fibers 22 are Is disposed between the support blocks 214 and exposed from the gap between the support blocks 214, and can increase the contact area between the heat conductive fibers 22 and the board body 21 and the outside to improve the heat dissipation of the heat conductive substrate 2. By adjusting the contact area of the light-emitting unit 3 with the heat-conducting fibers 22, the epitaxial effect of the light-emitting unit 3 from the heat-conductive substrate 2 can be optimized.

The second embodiment of the high thermal conductivity light-emitting diode of the present invention is substantially the same as the first embodiment, except that, in conjunction with FIG. 7, the plate body 21 has a plurality of holes 213, and the heat-conducting fibers 22 ( Shown in Figure 3) are distributed over the plate body 21 and portions are exposed from the holes 213. The holes 213 allow the heat-conducting fibers 22 to be exposed to the outside, thereby providing excellent heat conduction and heat dissipation, and also reducing the weight per unit volume of the plate body 21.

Specifically, the plate body 21 is selected from a polymer material suitable for foam molding such as thermosetting or thermoplastic, such as an epoxy resin, a phenol resin, a furan resin, etc., and is obtained by physical foaming or chemical foaming. . Since the related process control for foaming by using a polymer material is known in the art, no further explanation will be given. In the present embodiment, the plate body 21 is obtained by chemical foaming. It is to be noted that the purpose of the holes 213 is to allow the heat conducting fibers 22 to contact the outside by the holes 213 and to reduce the weight per unit volume of the plate body 21. However, although the holes 213 are more In many cases, the more the area of the heat conducting fibers 22 in contact with the outside, the more heat dissipation and the lighter weight per unit volume, but the excessive holes 213 also affect the mechanical strength of the board body 21, and therefore, in thermal conductivity, Preferably, the plate body 21 has a density of 0.4 to 0.9 g/cm ³ in consideration of the overall weight and mechanical strength.

In summary, the high thermal conductivity light-emitting diode of the present invention is formed on the thermally conductive substrate 2 having high thermal conductivity and heat dissipation by the light-emitting unit 3, since the thermally conductive substrate 2 has a thermally conductive fiber 22 having high thermal conductivity. The heat-conducting fibers 22 are exposed to the outside. Therefore, the heat energy generated by the light-emitting unit 3 during the operation is quickly guided away from the light-emitting unit 3 through the heat-conducting fibers 22 and is radiated to the outside, thereby providing excellent heat dissipation. Further, by forming the plate body 21 into a hollow or hole 213 structure, not only the heat conduction and heat dissipation of the heat conductive substrate 2 can be improved, but also the weight per unit volume of the plate body 21 can be reduced. The object of the invention can be achieved.

However, the above is only the embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent change and modification of the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

2‧‧‧thermal substrate

21‧‧‧ board body

211‧‧‧ base

212‧‧‧ bottom

3‧‧‧Lighting unit

31‧‧‧First type semiconductor layer

32‧‧‧ active layer

33‧‧‧Second type semiconductor layer

4‧‧‧Electrode unit

41‧‧‧ bottom electrode

42‧‧‧ top electrode

Claims (12)

A high thermal conductivity light emitting diode comprising: a thermally conductive substrate comprising a plate body and a plurality of thermally conductive fibers dispersed in the body of the plate, the plate body having a plurality of holes, a base surface, and a bottom surface opposite to the base surface And at least a portion of the heat conducting fibers are exposed from the holes outside the board; an illuminating unit is disposed on the base surface of the board body; and an electrode unit is electrically connected to the illuminating unit for providing The electric light enables the light emitting unit to emit light. The high thermal conductivity light-emitting diode according to claim 1, wherein the heat conductive fibers are arranged in a staggered manner and have a porous structure. The high thermal conductivity light-emitting diode according to claim 1, wherein the heat conductive fibers are exposed from the base surface. The high thermal conductivity light-emitting diode according to claim 3, wherein the heat conductive fibers are exposed from the bottom surface and directly contact the outside. The high thermal conductivity light-emitting diode according to claim 1, wherein the plate body further has a plurality of support blocks spaced apart from each other, and the heat conductive fibers are distributed between the support blocks and exposed from the gaps of the support blocks. The high thermal conductivity light-emitting diode according to claim 1, wherein the heat conductive fibers are arranged in a direction substantially perpendicular to the light emitting unit. The high thermal conductivity light-emitting diode according to claim 1, wherein the thermal conductivity of the thermal conductive fibers is between 380 and 2000 W/m. K. The high thermal conductivity light-emitting diode according to claim 7, wherein the heat conduction The fibers are selected from the group consisting of metal fibers, highly thermally conductive carbon fibers, or graphitized vapor deposited carbon fibers. The high thermal conductivity light-emitting diode according to claim 1, wherein the plate body is selected from the group consisting of a metal, an alloy metal, a thermosetting polymer or a thermoplastic polymer. The high thermal conductivity light-emitting diode according to claim 9, wherein the constituent material of the plate body is selected from one of the group consisting of silver, aluminum, copper, tin, antimony, aluminum oxide oxide, phenolic resin, and furan resin. , polyoxyl resin, epoxy resin. The high thermal conductivity light emitting diode of claim 1, wherein the light emitting unit comprises a first type semiconductor layer disposed on the thermally conductive substrate, an active layer formed on the first type semiconductor layer, and a Covering the second type semiconductor layer on the active layer, the electrode unit has a bottom electrode interposed between the heat conductive substrate and the light emitting unit, and a top electrode located on a top surface of the light emitting unit. The high thermal conductivity light-emitting diode according to claim 1, wherein the light-emitting unit comprises a first-type semiconductor layer disposed on the thermally-conductive substrate, and an active layer partially disposed on the first-type semiconductor layer, and a second type semiconductor layer on the active layer, the electrode unit having a bottom electrode formed on a surface of the first type semiconductor layer, and a top electrode formed on a surface of the second type semiconductor layer .