A flip-chip LED chip and its production process

Abstract

The present invention discloses a flip-chip LED chip and its production process, comprising a substrate, an n-pole conductive plate and a p-pole conductive plate embedded in the top of the substrate, a first positioning frame welded to the top of the n-pole conductive plate, a second positioning frame welded to the top of the p-pole conductive plate, a p-type gallium nitride layer disposed on the top of the substrate, an n-type gallium nitride layer disposed on the bottom outer wall of the p-type gallium nitride layer, an n-electrode disposed on the bottom outer wall of the n-type gallium nitride layer, the n-type gallium nitride layer located inside the first positioning frame, and solder disposed inside the first and second positioning frames. The present invention increases the electrode contact surface of the flip-chip LED chip and improves the thermal conductivity of the flip-chip LED chip by adding solder to the first and second positioning frames and then melting the solder to weld it to the n-pole conductive plate and the p-pole conductive plate.

Description

Technical Field

[0001] The present invention relates to the technical field of LED chips, and in particular to a flip-chip LED chip and a production process thereof. Background Art

[0002] A light-emitting diode (LED) is a semiconductor solid-state light-emitting device that utilizes the electroluminescence principle of a semiconductor PN junction. LED devices offer excellent optoelectronic properties, including low turn-on voltage, compact size, fast response, good stability, long life, and zero pollution. Consequently, they are finding increasing application in areas such as outdoor and indoor lighting, backlighting, displays, and traffic signs. Generally speaking, LED chips are classified into three types: horizontal (upright chip), vertical (vertical chip), and flip-chip (flip chip). In flip-chip LED chips, the P and N electrode layers are located on the same side of the light-emitting region. Light emitted by the active layer of the LED chip primarily escapes through the transparent sapphire layer, simplifying the production process.

[0003] Chinese Patent No. CN 201010227944.4 discloses an LED bracket and its production process. The bracket includes an insulating base and multiple conductive pins exposed on the insulating base. The conductive pins are metal-plated with a thickness of 5-100 microns. The LED bracket production process includes chemically plating a layer of metal on the entire injection-molded insulating base; then laser cutting the insulating base to etch away the metal in the laser path area to separate the positive and negative electrodes, forming multiple conductive pin precursors that distinguish the positive and negative electrodes; then electroplating a second metal layer on the conductive pin precursors to form conductive pin rear bodies; and finally, performing an etching process to obtain the conductive pins.

[0004] Chinese Patent No. CN 201510238966.3 provides a flip-chip LED chip and its manufacturing method. The flip-chip LED chip includes a substrate structure, an epitaxial layer, a contact layer, a first connecting electrode, a second connecting electrode, an insulating reflective layer, a first solder pad, and a second solder pad. The substrate structure of the flip-chip LED chip comprises a supporting substrate, a lattice matching layer, and a connecting dielectric layer having a periodically arranged columnar structure, which are formed in sequence. The connecting dielectric layer having a periodically arranged columnar structure partially exposes the lattice matching layer, and the crystal structure of the lattice matching layer is the same as that of the N-type semiconductor layer.

[0005] The existing flip-chip LED chips have a small contact area during soldering, resulting in poor thermal conductivity and the susceptibility to cold solder joints, which can cause the flip-chip LED chips to easily fall off the substrate. Therefore, there is an urgent need to design a flip-chip LED chip and its production process to address these issues. Summary of the Invention

[0006] The object of the present invention is to provide a flip-chip LED chip and a production process thereof to solve the above-mentioned deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A flip-chip LED chip includes a substrate, wherein an n-pole conductive plate and a p-pole conductive plate are embedded in the top of the substrate, a first positioning frame is welded to the top of the n-pole conductive plate, and a second positioning frame is welded to the top of the p-pole conductive plate. A p-type gallium nitride layer is provided on the top of the substrate, an n-type gallium nitride layer is provided on the bottom outer wall of the p-type gallium nitride layer, an n-electrode is provided on the bottom outer wall of the n-type gallium nitride layer, the n-type gallium nitride layer is located inside the first positioning frame, and solder is provided inside the first and second positioning frames.

[0009] Preferably, a p-electrode is provided on the bottom outer wall of the p-type gallium nitride layer, and the p-electrode is located inside the second positioning frame. The p-electrode is welded to the second positioning frame by means of welding material.

[0010] Preferably, a sapphire layer is provided on the top outer wall of the p-type gallium nitride layer, and an anti-corrosion layer is provided on the top outer wall of the sapphire layer.

[0011] Preferably, a quantum well layer is provided between the p-type gallium nitride layer and the n-type gallium nitride layer, and the thickness of the quantum well layer is 8-20 nm.

[0012] Preferably, conductor connecting pins are welded to the outer walls of the bottoms of the n-electrode and the p-electrode, and blocking pieces are integrally formed at the bottom ends of the conductor connecting pins.

[0013] Preferably, the bottom outer wall of the substrate is integrally formed with evenly distributed heat dissipation plates, and a heat dissipation gap is provided between two adjacent heat dissipation plates.

[0014] A production process for a flip-chip LED chip comprises the following steps:

[0015] Solder filling step: adding solder to the interior of the positioning frame 1 and the positioning frame 2 on the top of the substrate, and using a hot air gun to melt the solder inside the positioning frame 1 and the positioning frame 2, so that the solder inside the positioning frame 1 and the positioning frame 2 is welded to the n-pole conductive plate and the p-pole conductive plate, and the solder is kept in a molten state;

[0016] Assembly steps: Place the n-type gallium nitride layer into positioning frame one, and the p-electrode into positioning frame two. Place copper foil on top of the sapphire layer and apply pressure to the sapphire layer to ensure full contact between the n-electrode and the p-electrode and the solder.

[0017] Cooling step: While maintaining the pressure on the sapphire layer, a fan is used to blow air to the base and the p-type gallium nitride layer to cool and solidify the solder of the positioning frame 1 and the positioning frame 2;

[0018] Cleaning steps: Clean the solder that overflows from the outside of positioning frame 1 and positioning frame 2, and wipe off the dust on the top of the sapphire layer;

[0019] Steps for attaching the anti-corrosion layer: Apply adhesive evenly on the top of the sapphire layer, and then place the anti-corrosion layer on the top of the sapphire layer for bonding.

[0020] Preferably, in the solder filling step, the p-pole conductive plate and the n-pole conductive plate are both made of copper; in the assembling step, the n-electrode is obtained by deposition, the n-electrode material is NiAu, and the thickness of the n-electrode is 50nm-100nm; the p-electrode and the p-type gallium nitride layer are connected by welding; before the p-electrode and the p-type gallium nitride layer are welded, the p-type gallium nitride layer is first deposited to obtain an ohmic contact layer, and then the ohmic contact layer is welded to the p-electrode.

[0021] Preferably, the deposited n-electrode and ohmic contact layer are irradiated and annealed by using a laser with a wavelength of 248 mm, a frequency of 30 Hz, a pulse width of 2.5 ns, and a single pulse energy of 200-300 mJ.

[0022] Preferably, in the step of attaching the anti-corrosion layer, the adhesive is UV glue, and after the anti-corrosion layer and the sapphire layer are attached, the ultraviolet irradiation time is 1-2 minutes.

[0023] In the above technical solution, the present invention provides a flip-chip LED chip and a production process thereof, which have the following beneficial effects:

[0024] (1) The present invention increases the electrode contact surface of the flip-chip LED chip by adding solder to the interior of the first and second positioning frames, and then soldering the solder to the n-pole conductive plate and the p-pole conductive plate after the solder is melted, thereby improving the thermal conductivity of the flip-chip LED chip.

[0025] (2) The present invention uses the conductor connecting pins and the baffle to weld with the solder, so that the welding of the flip-chip LED chip is more firm, and the phenomenon of false soldering and detachment of the flip-chip LED chip is prevented.

[0026] (3) The present invention obtains an ohmic contact layer and an n-electrode by depositing NiAu, thereby reducing the contact resistance and allowing the light directed to the chip electrode surface to be reflected back to the side of the sapphire layer as much as possible, thereby ensuring good light extraction efficiency.

[0027] (4) The present invention uses laser irradiation annealing to make the surface of the n-electrode and the ohmic contact layer smoother, reduce the roughness of the electrode surface, and make the interface morphology better. Compared with the traditional annealing method, it takes less time and improves the processing efficiency of the LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 The present invention provides a schematic diagram of the overall structure of a flip-chip LED chip and its production process embodiment.

[0030] Figure 2 This is a schematic diagram of the enlarged structure of point A provided in an embodiment of a flip-chip LED chip and its production process of the present invention.

[0031] Figure 3 A control flow chart is provided for an embodiment of a flip-chip LED chip and its production process of the present invention.

[0032] Description of reference numerals:

[0033] 1. Substrate, 2. p-type gallium nitride layer, 3. n-electrode, 4. sapphire layer, 5. anti-corrosion layer, 6. quantum well layer, 7. n-type gallium nitride layer, 8. conductor connection pin, 9. n-pole conductive plate, 10. first positioning frame, 11. heat sink, 12. p-electrode, 13. heat dissipation gap, 14. solder, 15. second positioning frame, 16. p-pole conductive plate, 17. baffle. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] like Figure 1-3 As shown, an embodiment of the present invention provides a flip-chip LED chip, including a substrate 1, an n-pole conductive plate 9 and a p-pole conductive plate 16 embedded in the top of the substrate 1, a positioning frame 10 welded to the top of the n-pole conductive plate 9, a positioning frame 2 15 welded to the top of the p-pole conductive plate 16, a p-type gallium nitride layer 2 is provided on the top of the substrate 1, an n-type gallium nitride layer 7 is provided on the bottom outer wall of the p-type gallium nitride layer 2, an n-electrode 3 is provided on the bottom outer wall of the n-type gallium nitride layer 7, the n-type gallium nitride layer 7 is located inside the positioning frame 10, and solder 14 is provided inside the positioning frame 10 and the positioning frame 2 15.

[0036] Specifically, in this embodiment, it includes a substrate 1, which is made of ceramic material and has an electrostatic protection diode inside. An n-pole conductive plate 9 and a p-pole conductive plate 16 are embedded in the top of the substrate 1. A positioning frame 10 is welded to the top of the n-pole conductive plate 9, and a positioning frame 2 is welded to the top of the p-pole conductive plate 16. A p-type gallium nitride layer 2 is provided on the top of the substrate 1, and an n-type gallium nitride layer 7 is provided on the bottom outer wall of the p-type gallium nitride layer 2. The p-type gallium nitride layer 2 and the n-type gallium nitride layer 7 are inherent parts of the LED chip. An n-electrode 3 is provided on the bottom outer wall of the n-type gallium nitride layer 7. The n-electrode 3 is used for conducting electricity and reflecting light to the n-type gallium nitride layer 7. The n-type gallium nitride layer 7 is located inside the positioning frame 10. Solder 14 is provided inside the positioning frame 10 and the positioning frame 2 15. The positioning frame 10 serves to position the solder 14, and the solder 14 is tin.

[0037] The present invention provides a flip-chip LED chip and a production process thereof. The present invention increases the electrode contact surface of the flip-chip LED chip and improves the thermal conductivity of the flip-chip LED chip by adding solder 14 to the interior of a positioning frame 10 and a positioning frame 2 15, and then melting the solder 14 and soldering it to an n-pole conductive plate 9 and a p-pole conductive plate 16.

[0038] In another embodiment provided by the present invention, a p-electrode 12 is provided on the bottom outer wall of the p-type gallium nitride layer 2. The p-electrode 12 is located inside the second positioning frame 15. The p-electrode 12 is welded to the second positioning frame 15 through a solder 14. The second positioning frame 15 is used to position the molten solder 14 so that the p-electrode 12 can achieve good welding contact with the solder 14.

[0039] In another embodiment provided by the present invention, a sapphire layer 4 is provided on the top outer wall of the p-type gallium nitride layer 2, and an anti-corrosion layer 5 is provided on the top outer wall of the sapphire layer 4. The anti-corrosion layer 5 is made of Schott glass material, so that the surface of the sapphire layer 4 has extremely strong acid and alkali resistance.

[0040] In another embodiment provided by the present invention, a quantum well layer 6 is provided between the p-type gallium nitride layer 2 and the n-type gallium nitride layer 7. The quantum well layer 6 has a thickness of 10 nm and is formed by the alternating arrangement of the p-type gallium nitride layer 2 and the n-type gallium nitride layer 7. It is a potential well for electrons or holes with a significant quantum confinement effect.

[0041] In another embodiment provided by the present invention, the bottom outer walls of the n-electrode 3 and the p-electrode 12 are welded with a conductor connecting pin 8, and the bottom end of the conductor connecting pin 8 is integrally formed with a baffle 17. The conductor connecting pin 8 and the baffle 17 are welded with the solder 14, so that the welding of the flip-chip LED chip is more firm, preventing the flip-chip LED chip from having a cold solder joint and detaching.

[0042] In another embodiment provided by the present invention, the bottom outer wall of the substrate 1 is integrally formed with evenly distributed heat dissipation plates 11 , and a heat dissipation gap 13 is provided between two adjacent heat dissipation plates 11 .

[0043] A production process for a flip-chip LED chip comprises the following steps:

[0044] Solder filling step: adding solder 14 to the interior of the positioning frame 10 and the positioning frame 2 15 on the top of the substrate 1, and using a hot air gun to melt the solder 14 inside the positioning frame 10 and the positioning frame 2 15, so that the solder 14 inside the positioning frame 10 and the positioning frame 2 15 is welded to the n-pole conductive plate 9 and the p-pole conductive plate 16, and the solder 14 is kept in a molten state;

[0045] Assembly steps: Install the n-type gallium nitride layer 7 into the interior of the first positioning frame 10, install the p-electrode 12 into the interior of the second positioning frame 15, place copper foil on top of the sapphire layer 4, and apply pressure to the sapphire layer 4 to ensure that the n-electrode 3 and the p-electrode 12 are in full contact with the solder 14;

[0046] Cooling step: using a fan to blow air to the base and the p-type gallium nitride layer 2 while maintaining the pressure of the sapphire layer 4, so that the solder 14 of the positioning frame 10 and the positioning frame 2 15 is cooled and solidified;

[0047] Cleaning step: clean the solder 14 overflowing from the outside of the positioning frame 10 and the positioning frame 2 15, and wipe off the dust on the top of the sapphire layer 4;

[0048] Anti-corrosion layer attaching step: evenly apply adhesive on the top of the sapphire layer 4, and then place the anti-corrosion layer 5 on the top of the sapphire layer 4 for bonding;

[0049] In another embodiment provided by the present invention, in the solder filling step, the p-pole conductive plate 16 and the n-pole conductive plate 9 are both made of copper, and the positioning frame 10 and the positioning frame 2 15 are also made of copper. In the assembly step, the n-electrode 3 is obtained by deposition, and the n-electrode 3 is made of NiAu, and the thickness of the n-electrode 3 is 50nm. The p-electrode 12 and the p-type gallium nitride layer 2 are connected by welding. Before the p-electrode 12 and the p-type gallium nitride layer 2 are welded, the p-type gallium nitride layer 2 is first deposited to obtain an ohmic contact layer, and then the ohmic contact layer is welded to the p-electrode 12. The NiAu deposition method is used to obtain the ohmic contact layer and the n-electrode 3, so that the contact resistance is reduced, and the light incident on the chip electrode surface can be reflected back to the side of the sapphire layer 4 as much as possible, thereby ensuring good light extraction efficiency.

[0050] In another embodiment provided by the present invention, the deposited n-electrode 3 and the ohmic contact layer are irradiated and annealed by a laser with a wavelength of 248 mm, a frequency of 30 Hz, a pulse width of 2.5 ns, and a single pulse energy of 200 mj. Laser irradiation annealing makes the surface of the n-electrode 3 and the ohmic contact layer smoother, reduces the roughness of the electrode surface, and makes the interface morphology better. Compared with traditional annealing methods, it takes less time, thereby improving the processing efficiency of the LED chip.

[0051] In another embodiment provided by the present invention, in the step of attaching the anti-corrosion layer, the adhesive is UV adhesive, and after the anti-corrosion layer 5 and the sapphire layer 4 are attached, ultraviolet irradiation time is 1 minute to allow the adhesive to be completely cured.

[0052] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A flip-chip LED chip, comprising a substrate (1), characterized in that: An n-pole conductive plate (9) and a p-pole conductive plate (16) are embedded in the top of the substrate (1); a positioning frame (10) is welded to the top of the n-pole conductive plate (9); a positioning frame (15) is welded to the top of the p-pole conductive plate (16); a p-type gallium nitride layer (2) is provided on the top of the substrate (1); an n-type gallium nitride layer (7) is provided on the bottom outer wall of the p-type gallium nitride layer (2); an n-electrode (3) is provided on the bottom outer wall of the n-type gallium nitride layer (7); the n-type gallium nitride layer (7) is located inside the positioning frame (10); and solder (14) is provided inside the positioning frame (10) and the positioning frame (15); A p-electrode (12) is provided on the bottom outer wall of the p-type gallium nitride layer (2), the p-electrode (12) is located inside the second positioning frame (15), and the p-electrode (12) is welded to the second positioning frame (15) via a welding material (14); A sapphire layer (4) is provided on the top outer wall of the p-type gallium nitride layer (2), and an anti-corrosion layer (5) is provided on the top outer wall of the sapphire layer (4); A quantum well layer (6) is provided between the p-type gallium nitride layer (2) and the n-type gallium nitride layer (7), and the thickness of the quantum well layer (6) is 8-20 nm; Conductor connection pins (8) are welded to the bottom outer walls of the n-electrode (3) and the p-electrode (12), and a baffle (17) is integrally formed at the bottom end of the conductor connection pin (8); The bottom outer wall of the substrate (1) is integrally formed with evenly distributed heat dissipation plates (11), and a heat dissipation gap (13) is provided between two adjacent heat dissipation plates (11).

2. A production process for a flip-chip LED chip, comprising the flip-chip LED chip according to claim 1, characterized in that: The following steps are involved: Filling solder step: adding solder (14) to the interior of the positioning frame 1 (10) and the positioning frame 2 (15) on the top of the substrate (1), and using a hot air gun to melt the solder (14) inside the positioning frame 1 (10) and the positioning frame 2 (15), so that the solder (14) inside the positioning frame 1 (10) and the positioning frame 2 (15) are welded to the n-pole conductive plate (9) and the p-pole conductive plate (16), and the solder (14) is kept in a molten state; Assembling steps: placing the n-type gallium nitride layer (7) into the interior of the first positioning frame (10), placing the p-electrode (12) into the interior of the second positioning frame (15), placing a copper foil on top of the sapphire layer (4), and applying pressure to the sapphire layer (4) so ​​that the n-electrode (3) and the p-electrode (12) are in full contact with the solder (14); Cooling step: using a blower to blow air to the base and the p-type gallium nitride layer (2) while maintaining the pressure of the sapphire layer (4), so that the solder (14) of the positioning frame 1 (10) and the positioning frame 2 (15) are cooled and solidified; Cleaning step: clean the solder (14) overflowing from the outside of positioning frame 1 (10) and positioning frame 2 (15), and wipe the dust on the top of the sapphire layer (4); Step of attaching the anti-corrosion layer: evenly apply adhesive to the top of the sapphire layer (4), and then place the anti-corrosion layer (5) on the top of the sapphire layer (4) for bonding.

3. The production process of a flip-chip LED chip according to claim 2, characterized in that: In the solder filling step, the p-pole conductive plate (16) and the n-pole conductive plate (9) are both made of copper. In the assembly step, the n-electrode (3) is obtained by deposition. The n-electrode (3) is made of NiAu and has a thickness of 50nm-100nm. The p-electrode (12) and the p-type gallium nitride layer (2) are connected by welding. Before the p-electrode (12) and the p-type gallium nitride layer (2) are welded, the p-type gallium nitride layer (2) is first deposited to obtain an ohmic contact layer, and then the ohmic contact layer is welded to the p-electrode (12).

4. The production process of a flip-chip LED chip according to claim 3, characterized in that: The deposited n-electrode (3) and the ohmic contact layer are subjected to irradiation annealing using a laser having a wavelength of 248 mm, a frequency of 30 Hz, a pulse width of 2.5 ns, and a single pulse energy of 200-300 mJ.

5. The production process of a flip-chip LED chip according to claim 2, characterized in that: In the step of attaching the anti-corrosion layer, the adhesive is UV glue, and after the anti-corrosion layer (5) and the sapphire layer (4) are attached, ultraviolet irradiation time is 1-2 minutes.

Images