TWI470836B - Light-emitting diode package structure - Google Patents

Description

Light emitting diode package structure

The present invention relates to a package structure, and more particularly to a light-emitting diode package structure.

The light-emitting diode has a P/N junction, and a voltage is applied to the P/N junction of the light-emitting diode to cause the light-emitting diode to emit light. Light-emitting diode elements are widely used in a variety of applications, such as indicators, signage, lighting, and other types of lighting elements. Light-emitting diodes (LEDs) have gradually replaced traditional light bulbs due to their small size, long service life, low power consumption and high brightness, making them the most important light-emitting components.

Traditionally, surface mount technology (SMT) has been used to fabricate light-emitting diodes. 1A-1D shows a schematic diagram of a conventional package process using surface mount technology, wherein the package structure is a horizontal package structure. In Fig. 1A, a lead-frame 11 is first provided, which includes a heat sink block 11a, a plurality of wire legs 11b, and a body portion 11c. Next, as shown in FIG. 1B, the light-emitting diode chip 21 is fixed on the heat-dissipating block 11a in the holder 11 by using a solid crystal glue, wherein the wafer 21 includes two opposite-electrode electrodes 21b, 21c on the surface of the wafer 21. on. After the wafer 21 is fixed, the wire 31 is made to electrically connect the electrodes 21a, 21b on the wafer 21 to a plurality of wire legs 11b, wherein the wires 31 are as shown in Fig. 1C. After the wire bonding 31 is completed, in the recess of the main body portion 11c including the wafer 21, the wires 31, and the wire legs 11b, the encapsulant 41 is poured to complete the packaging as shown in Fig. 1D.

The light-emitting diode is fabricated by a conventional surface-adhesive technology process, and the light-emitting diode chip is fabricated on the support by a method of solid crystal, wire bonding, dispensing, etc., and then the soldering paste is used for re-welding to fix the package structure to the laid circuit. On the circuit board. This process is not only cumbersome and time consuming, but also has the disadvantages of wire breakage, encapsulation peeling, poor heat dissipation of the solid crystal glue, and the fabricated LED package structure has a millimeter size, and the size cannot be further reduced.

Therefore, an improved light emitting diode package structure needs to be proposed to overcome the above disadvantages.

The invention relates to a light emitting diode package structure, comprising: a fluorescent substrate; a light emitting diode chip disposed on the fluorescent substrate, the light emitting diode chip has a pair of electrodes; The phosphor substrate is electrically connected to the pair of electrodes of the LED chip; a protective layer is formed on the LED chip and has an opening to expose a portion of the LED chip; A heat dissipating block is disposed on the protective layer and fills the opening.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

The embodiments of the present invention are described in detail below with reference to the drawings, and the same reference numerals are used in the drawings or the description of the same or similar parts, and in the drawings, the shapes of the embodiments or The thickness can be enlarged and simplified or conveniently marked. Further, portions of the various elements in the drawings will be described separately, and it is noted that elements not shown or described in the drawings are shapes known to those of ordinary skill in the art. In addition, when a layer is described as being "an" another layer (or substrate), it can mean that the layer is in direct contact with another layer (or substrate) or otherwise. In addition, the specific embodiments are merely illustrative of specific ways of using the invention, and are not intended to limit the invention.

The light emitting diode package structure of the present invention firstly fixes a light emitting diode chip on a fluorescent substrate, and then completes a circuit, a protective layer, a heat dissipating block or a heat dissipating substrate by a semiconductor process, and can be formed into a micron level. Ultra-thin LED package.

2 is a cross-sectional view of a light emitting diode package structure 200 in accordance with an embodiment of the present invention. First, a fluorescent substrate 10 is provided, wherein the fluorescent substrate 10 may include a ceramic fluorescent substrate or a silicone fluorescent substrate. The phosphor substrate 10 may have a thickness of about 10 to 40 μm. In some embodiments, the ceramic phosphor substrate 10 can be formed by calcining a mixture of phosphor powder and ceramic powder, such as alumina or cerium oxide powder. In other embodiments, the silicone phosphor substrate 10 can be formed by first mixing a mixture of phosphor powder and plastic, and then ejecting the kneaded mixture to obtain a desired substrate, wherein the plastic is, for example, a ring-shaped embedded layer. A cyclic block copolymer (CBC) or a cyclic olefin copolymer (COC).

Next, a light emitting diode chip 20 is disposed on the fluorescent substrate 10. The light-emitting diode wafer 20 has a pair of electrodes 20a disposed on the upper surface of the wafer 20, which are respectively a P electrode and an N electrode. In some embodiments, the wafer 20 can be disposed by first forming a transparent adhesive (not shown), including epoxy or silicone, on the area of the fluorescent substrate 10 where the light-emitting diode wafer 20 is to be disposed, and then The wafer 20 is disposed on the transparent adhesive, thereby bonding the wafer 20 and the fluorescent substrate 10. The LED substrate 20 can be a horizontal wafer and includes at least a p-type semiconductor layer, an active region and an n-type semiconductor layer, wherein the active region is between the p-type and n-type semiconductor layers. In addition, a metal reflective layer may be selectively formed on the side of the wafer 20 opposite to the fluorescent substrate 10. The metal reflective layer may be made of Al, Ag, Ni, Ph, Pd, Pt, Ru, Au, and any of the above. combination. The p-type, n-type semiconductor layer may be a III-V semiconductor material, such as a III-V GaN material, and have Al _x Ga _y In _(1-xy) N (0≦x≦1, 0≦y≦1 ) said. The light emitted from the LED chip 20 is preferably blue light or ultraviolet light, but may be other suitable wavelengths, and the emitted light will be directed toward the fluorescent substrate 10 based on the direction shown in FIG. Issued below, as indicated by arrow 15. If the light emitted by the LED substrate 20 is blue light or ultraviolet light, the final light-emitting color of the suitable fluorescent substrate light-emitting diode package structure 200 can be mixed into white light. In some embodiments, the light emitting diode chip 20 can have a thickness of about 70-90 μm.

After the light-emitting diode chip 20 is placed on the fluorescent substrate 10, a line 30 is disposed on the fluorescent substrate 10. The line 30 is located on the upper surface of the fluorescent substrate 10. Further, the line 30 extends along the sidewall of the wafer 20 and is electrically connected to the electrode 20a. Therefore, at least a portion of the line 30 is disposed on the wafer 20. The material of line 30 can be gold, copper or other metal with good electrical conductivity. The formation of line 30 may utilize deposition, lithography, etching, etc., where deposition may utilize chemical vapor deposition, physical vapor deposition, electroplating, or other suitable deposition methods, and the etching may be dry etching or wet etching.

Next, a protective layer 40 is formed on the LED substrate 20, wherein the protective layer 40 has an opening 40a above the wafer 20 to partially expose the LED wafer 20. For example, the protective layer 40 may be blanket-covered above by chemical vapor deposition or other suitable deposition method, and the opening 40a may be formed by a photolithography and etching process. The size or shape of the opening 40a is not limited and can be adjusted as needed. The protective layer 40 may have a thickness of about 90-110 μm. The material of the protective layer 40 may include polyamidamine, butylcyclobutene (BCB), parylene, polynaphthalenes, fluorocarbons, acrylates or Combination of the foregoing.

After forming the protective layer 40, in some embodiments, it further includes conformingly forming an adhesive layer 50 on the upper surface of the protective layer 40 and in the opening 40a. The adhesive layer 50 functions primarily to bond the protective layer 40 and the heat sink 60 to be formed. The material of the adhesive layer 50 may include Ti and Cu. The thickness of the adhesive layer 50 can be about 5-10 μm. In other embodiments, the above adhesive layer may not be formed.

Next, a heat dissipating block 60 is disposed on the protective layer 40 and filled in the opening 40a. The material of the heat slug 60 may be various conventional heat dissipating materials such as copper, aluminum or aluminum alloy. The thickness t of the thickest portion of the heat slug 60 can be about 40-60 μm.

After the heat slug 60 is formed on the protective layer 40, a eutectic layer 70 may be formed over the heat slug 60. The material of the eutectic layer 70 may be gold tin alloy (AuSn) or at least one of the following materials: Au, Ti, Ni, Pt, Rh, Al, In, and Sn. The eutectic layer 70 may have a thickness of about 1-5 μm. The eutectic layer 70 functions to bond the light emitting diode package structure 200 to, for example, a circuit board by using the layer, and the lower bonding temperature of the eutectic material allows the subsequent bonding to be performed at a lower temperature. In addition, in addition to the good thermal conductivity provided by the heat slug 6, the eutectic layer can provide additional thermal conductivity, which makes the overall thermal conductivity of the LED package 200 better.

Referring to FIG. 2, a light emitting diode package structure 200 according to an embodiment of the present invention includes a fluorescent substrate 10, and a light emitting diode chip 20, a line 30, and a protection formed on the fluorescent substrate 10 in sequence. Layer 40, adhesive layer 50, heat slug 60 and eutectic layer 70. The light emitting diode chip 20 is disposed on the fluorescent substrate 10 and has a pair of electrodes 20a disposed on the upper surface of the wafer 20. The line 30 is disposed on the fluorescent substrate 10 and extends along the sidewall of the wafer 20 and is electrically connected to the electrode 20a. Therefore, at least a portion of the wiring 30 is disposed on the wafer 20. The protective layer 40 is formed on the wafer 20 and has an opening to expose a portion of the wafer 20. The heat dissipation block 60 is formed on the protective layer 40 and filled in the opening of the protective layer 40.

Therefore, as shown in FIG. 2, the LED package structure 200 of the embodiment of the present invention may have a total thickness T of about 130-200 μm, for example, less than about 200 μm. That is to say, the light emitting diode package structure provided by the present invention can have a total thickness of a micron order. The LED package structure of the invention also has the following advantages, such as no need for wire bonding, no encapsulation glue, and no gap between the wafer and the substrate to increase heat dissipation, so that, for example, the process is complicated, time-consuming, and broken. The disadvantages of poor peeling of the encapsulant and poor heat dissipation of the solid crystal adhesive.

The present invention has been disclosed in the above preferred embodiments, and is not intended to limit the scope of the present invention. Any one of ordinary skill in the art can make a few changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

10. . . Fluorescent substrate

11. . . support

11a, 60. . . Heat sink

11b. . . Wire foot

11c. . . main part

15. . . Light direction

20, 21. . . Light-emitting diode chip

20a, 21a, 21b. . . electrode

30. . . line

31. . . wire

40. . . The protective layer

41. . . Packaging adhesive

40a. . . Opening

50. . . Adhesive layer

70. . . Eutectic layer

200. . . Light emitting diode package structure

t, T. . . thickness

Figures 1A-1D show a schematic cross-sectional view of a conventional packaging process using surface mount technology.

2 is a cross-sectional view of a light emitting diode package structure 200 in accordance with an embodiment of the present invention.

10. . . Fluorescent substrate

15. . . Light direction

20. . . Light-emitting diode chip

20a. . . electrode

30. . . line

40. . . The protective layer

40a. . . Opening

50. . . Adhesive layer

60. . . Heat sink

70. . . Eutectic layer

200. . . Light emitting diode package structure

t, T. . . thickness

Claims (12)

A light emitting diode package structure comprising: a fluorescent substrate; a light emitting diode chip disposed on the fluorescent substrate, the light emitting diode chip having a pair of electrodes; and a circuit disposed on the fluorescent substrate And electrically connected to the pair of electrodes of the LED chip; a protective layer is formed on the LED chip, and has an opening to expose a portion of the LED chip; and a heat dissipation block, It is disposed on the protective layer and fills the opening. The light emitting diode package structure according to claim 1, wherein the fluorescent substrate comprises a ceramic fluorescent substrate or a silicone fluorescent substrate. The light emitting diode package structure according to claim 1, wherein the protective layer comprises polyamidamine, benzocyclobutene, parylene, naphthalene polymer, fluorocarbon, acrylate or the foregoing combination. The light emitting diode package structure of claim 1, further comprising an adhesive layer conformally formed on the upper surface of the protective layer and the opening. The light emitting diode package structure according to claim 4, wherein the material of the adhesive layer comprises Ti and Cu. The light emitting diode package structure of claim 1, further comprising a eutectic layer formed over the heat dissipation block. The light-emitting diode package structure according to claim 6, wherein the eutectic layer is made of a gold-tin alloy. The light emitting diode package structure of claim 6, wherein the eutectic layer has a thickness of about 1-5 μm. The light emitting diode package structure of claim 1, further comprising a transparent adhesive formed between the fluorescent substrate and the light emitting diode chip. The light emitting diode package structure of claim 9, wherein the transparent adhesive comprises epoxy resin or silicone rubber. The light-emitting diode package structure according to claim 1, wherein the thickness is not more than 200 micrometers. The light emitting diode package structure of claim 1, wherein the pair of electrodes are disposed on an upper surface of the light emitting diode chip, and the line extends along the sidewall of the light emitting diode chip to the pair of electrodes .