Deep ultraviolet LED device packaging process

Abstract

The invention provides a deep ultraviolet LED device packaging technology, and relates to the technical field of semiconductor photoelectric device packaging. The deep ultraviolet LED device packaging process comprises the following steps: carrying out cleaning and surface treatment on a deep ultraviolet LED chip; selecting a packaging substrate, and carrying out surface metallization treatment on the packaging substrate; fixing the pretreated deep ultraviolet LED chip at a preset position on the packaging substrate by using silver colloid, and connecting an electrode of the deep ultraviolet LED chip with the corresponding packaging substrate by adopting a gold wire bonding process; the periphery of the deep ultraviolet LED chip is filled with an organic silicon material, and a quartz glass cover plate covers the organic silicon material; and installing a metal radiating fin on the back surface of the packaging substrate. By selecting the quartz glass cover plate with high light transmittance and the fluorine-containing organic silicon resin filling material with low refractive index, the total reflection of light in the packaging part is reduced, the light emitting efficiency is improved, and compared with the traditional packaging process, the light emitting efficiency can be improved by 20-30%.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic device packaging, and specifically to a packaging process for deep ultraviolet LED devices. Background Art

[0002] Due to the wide applications of deep ultraviolet LEDs in fields such as sterilization and disinfection, biomedicine, water purification, and photocuring, the market demand is increasing day by day. However, there are many problems in the traditional packaging process of deep ultraviolet LED devices, which limit the performance improvement and application expansion of deep ultraviolet LEDs.

[0003] 1. Low light extraction efficiency: In the existing packaging process, when the light emitted by the deep ultraviolet LED chip propagates from the chip to the outside of the package, due to the mismatch of material refractive indices and the unreasonable design of the package structure, a large amount of light undergoes total internal reflection inside, unable to be effectively emitted, greatly reducing the light extraction efficiency and limiting the application of deep ultraviolet LEDs in scenarios with high requirements for optical power.

[0004] 2. Poor heat dissipation performance: A large amount of heat is generated during the operation of deep ultraviolet LEDs. If it cannot be dissipated in a timely and effective manner, it will cause the chip temperature to rise, which in turn leads to a decline in the optoelectronic performance of the device, such as emission wavelength drift and emission efficiency reduction, seriously affecting the service life and reliability of the device. The heat dissipation capabilities of traditional packaging materials and structures are insufficient to meet the increasing power requirements of deep ultraviolet LEDs.

[0005] Therefore, it is of great practical significance and market value to develop a packaging process for deep ultraviolet LED devices that can improve the light extraction efficiency, enhance the heat dissipation performance, simplify the process, and reduce costs. Summary of the Invention

[0006] (I) Technical problems to be solved

[0007] In view of the deficiencies of the prior art, the present invention provides a packaging process for deep ultraviolet LED devices, which solves the problems raised in the above background art.

[0008] (II) Technical solutions

[0009] To achieve the above objectives, the present invention is realized through the following technical solutions: A packaging process for deep ultraviolet LED devices, comprising the following steps:

[0010] Step 1: Chip pretreatment:

[0011] Clean and surface-treat the deep ultraviolet LED chip to remove impurities and contaminants on the surface of the deep ultraviolet LED chip;

[0012] Step 2: Selection and treatment of packaging substrate:

[0013] Select a ceramic substrate with high thermal conductivity as the packaging substrate and perform surface metallization on the packaging substrate;

[0014] Step 3: Die bonding and wire bonding:

[0015] Die bonding: Use silver glue to fix the pre-treated deep ultraviolet LED chip at a predetermined position on the packaging substrate;

[0016] Wire bonding: Adopt the gold wire bonding process to connect the electrodes of the deep ultraviolet LED chip to the corresponding positive and negative regions of the packaging substrate through gold wires;

[0017] Step 4: Filling and sealing:

[0018] Fill an organosilicon material with high light transmittance, low refractive index and good ultraviolet resistance around the deep ultraviolet LED chip, with the filling height higher than the chip, and then cover a quartz glass cover plate above it, and seal and fix the quartz glass cover plate to the packaging substrate through ultraviolet curable glue;

[0019] Step 5: Optimization of the heat dissipation structure:

[0020] Install a metal heat sink on the back of the packaging substrate, and coat the first lens silicone between the metal heat sink and the packaging substrate to form a number of first hemispherical lenses, and the first hemispherical lens is a hemispherical convex lens structure.

[0021] Preferably, in step 1, the chip pretreatment includes using the plasma cleaning technology to treat the surface of the deep ultraviolet LED chip with inert gas plasma for 5-10 minutes under the conditions of a vacuum degree of 10-100 Pa and a radio frequency power of 200-500 W; wherein, the inert gas is one or a mixture of argon and helium.

[0022] Preferably, in step 2, the ceramic substrate with high thermal conductivity is an aluminum nitride substrate or an alumina substrate; the metallization treatment is to deposit a copper or silver metal layer with a thickness of 1-3 μm on the surface of the packaging substrate by magnetron sputtering or electroless plating.

[0023] Preferably, in step 3, in the die bonding step, the curing temperature of the silver glue is 160-170 °C and the curing time is 22-28 minutes; in the wire bonding step, the bonding parameters of the gold wire bonding process are: ultrasonic power 50-80 mW, bonding pressure 10-20 g, bonding time 5-10 ms, the diameter of the gold wire is 15-25 μm, and the packaging substrate is divided into a positive region and a negative region, and multiple packaging substrates are arranged in an array in a manner that the positive and negative electrode placement orders of adjacent packaging substrates are opposite, wherein, both the positive and negative regions of the packaging substrate are provided with metal eutectic bonding layers, and the deep ultraviolet LED chip is electrically connected to the positive and negative regions of the packaging substrate through the metal eutectic bonding layer.

[0024] Preferably, in step four, the silicone material is a fluorinated silicone resin with a refractive index between 1.3 and 1.4 and a light transmittance of more than 90%; the ultraviolet curing condition is irradiation under an ultraviolet lamp with a wavelength of 365 nm for 5 to 10 minutes.

[0025] Preferably, in step five, the metal heat sink is made of aluminum or copper with a thickness of 1 to 3 mm; the thermal conductivity of the first lens silicone is not less than 5 W / (m·K).

[0026] Preferably, in step five, a first silicone layer is coated on the upper part of the first hemispherical lens, and a second lens silicone is coated on the first silicone layer to form a plurality of second hemispherical lenses, and the second hemispherical lens is a hemispherical convex lens structure; a second silicone layer is coated on the upper part of the second hemispherical lens; wherein, at least one of the second hemispherical lens and the second silicone layer has phosphor.

[0027] (III) Beneficial effects

[0028] The present invention provides a deep ultraviolet LED device packaging process, which has the following beneficial effects:

[0029] 1. Improve the light extraction efficiency: By selecting a quartz glass cover plate with high light transmittance and a fluorinated silicone resin filling material with low refractive index, the total reflection of light inside the package is reduced, and the light extraction efficiency is improved. Compared with the traditional packaging process, the light extraction efficiency can be increased by 20% - 30%.

[0030] 2. Improve the heat dissipation performance: Adopt a ceramic substrate and a metal heat sink with high thermal conductivity, and cooperate with thermal conductive silicone to form a good heat dissipation channel, which can quickly dissipate the heat generated by the chip, effectively reduce the chip temperature, improve the optoelectronic performance and reliability of the device, and extend the service life of the device. Description of the drawings

[0031] Figure 1 It is a schematic diagram of the packaging process flow of the present invention. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0033] Example 1:

[0034] As Figure 1As shown in the figure, an embodiment of the present invention provides a packaging process for deep ultraviolet LED devices, including the following steps:

[0035] Step 1: Chip pretreatment:

[0036] Clean and surface-treat the deep ultraviolet LED chip to remove impurities and contaminants on the surface of the deep ultraviolet LED chip; specifically, the chip pretreatment includes using plasma cleaning technology to treat the surface of the deep ultraviolet LED chip with inert gas plasma for 5-10 minutes under the conditions of a vacuum degree of 10-100 Pa and a radio frequency power of 200-500 W; wherein, the inert gas is one or more mixtures of argon and helium.

[0037] Step 2: Selection and treatment of packaging substrate:

[0038] Select a ceramic substrate with high thermal conductivity as the packaging substrate and perform surface metallization treatment on the packaging substrate; specifically, the ceramic substrate with high thermal conductivity is an aluminum nitride substrate or an alumina substrate; the metallization treatment is to deposit a layer of copper or silver metal layer with a thickness of 1-3 μm on the surface of the packaging substrate by magnetron sputtering or electroless plating.

[0039] Step 3: Die bonding and wire bonding:

[0040] Die bonding: Use silver glue to fix the pretreated deep ultraviolet LED chip at a predetermined position on the packaging substrate; specifically, in the die bonding step, the curing temperature of the silver glue is 160-170 °C, and the curing time is 22-28 minutes;

[0041] Wire bonding: Adopt the gold wire bonding process to connect the electrodes of the deep ultraviolet LED chip to the corresponding positive electrode area and negative electrode area of the packaging substrate through gold wires; specifically, in the wire bonding step, the bonding parameters of the gold wire bonding process are: ultrasonic power 50-80 mW, bonding pressure 10-20 g, bonding time 5-10 ms, the diameter of the gold wire is 15-25 μm, and the packaging substrate is divided into a positive electrode area and a negative electrode area, and multiple packaging substrates are arranged in an array in a way that the positive and negative electrode placement orders of adjacent packaging substrates are opposite. Among them, metal eutectic bonding layers are provided in both the positive electrode area and the negative electrode area of the packaging substrate, and the deep ultraviolet LED chip is electrically connected to the positive electrode area and the negative electrode area of the packaging substrate through this metal eutectic bonding layer.

[0042] Step 4: Filling and sealing:

[0043] A silicone material with high light transmittance, low refractive index and good ultraviolet resistance is filled around the deep ultraviolet LED chip. Specifically, the silicone material is a fluorinated silicone resin, whose refractive index is between 1.3 and 1.4, the light transmittance is above 90%, and its filling height is higher than the chip. Then a quartz glass cover plate is covered on it, and the quartz glass cover plate and the encapsulation substrate are sealed and fixed with an ultraviolet curing adhesive. The ultraviolet curing condition is to irradiate under an ultraviolet lamp with a wavelength of 365nm for 5 - 10 minutes;

[0044] Step Five: Optimization of the heat dissipation structure:

[0045] A metal heat sink is installed on the back of the encapsulation substrate. Among them, the material of the metal heat sink is aluminum or copper, and its thickness is 1 - 3mm. A first lens silicone is coated between the metal heat sink and the encapsulation substrate. The thermal conductivity of the first lens silicone is not less than 5W / (m·K) to form a number of first hemispherical lenses, and the first hemispherical lenses are hemispherical convex lens structures; A first silicone layer is coated on the upper part of the first hemispherical lenses, and a second lens silicone is coated on the first silicone layer to form a number of second hemispherical lenses, and the second hemispherical lenses are hemispherical convex lens structures; A second silicone layer is coated on the upper part of the second hemispherical lenses; Among them, at least one of the second hemispherical lenses and the second silicone layer has phosphor.

[0046] Example Two:

[0047] Select an aluminum nitride ceramic substrate with a size of 5mm×5mm, and perform surface magnetron sputtering copper plating treatment on it. The thickness of the copper layer is 1.5μm.

[0048] The deep ultraviolet LED chip is fixed on the substrate with silver paste and baked in an oven at 160°C for 25 minutes to cure the silver paste.

[0049] Use a gold wire bonder for wire bonding, with an ultrasonic power of 60mW, a bonding pressure of 15g, and a bonding time of 8ms.

[0050] Fill the fluorinated silicone resin around the chip, with a filling height of 0.3mm, then cover a 5mm×5mm quartz glass cover plate, seal it with an ultraviolet curing adhesive, and irradiate it under a 365nm ultraviolet lamp for 8 minutes to cure.

[0051] An aluminum heat sink with a size of 10 mm × 10 mm is mounted on the back of the substrate, and the first lens silicone is applied. The thermal conductivity of the first lens silicone is not less than 5 W / (m·K), and a number of first hemispherical lenses are formed. The first hemispherical lenses are hemispherical convex lens structures; a first silicone layer is coated on the upper part of the first hemispherical lenses, and a second lens silicone is coated on the first silicone layer to form a number of second hemispherical lenses. The second hemispherical lenses are hemispherical convex lens structures; a second silicone layer is coated on the upper part of the second hemispherical lenses; wherein, at least one of the second hemispherical lenses and the second silicone layer has phosphor.

[0052] The performance of the packaged deep ultraviolet LED device is tested. The light extraction efficiency is increased by 23% compared with the traditional process. After continuous operation for 1000 hours, the chip temperature rise does not exceed 15 °C, and the device performance is stable.

[0053] Example 3:

[0054] An alumina ceramic substrate with a size of 8 mm × 8 mm is used and chemically plated with silver. The thickness of the silver layer is 2 μm.

[0055] The deep ultraviolet LED chip is fixed on the substrate with silver glue and baked in an oven at 170 °C for 28 minutes to cure the silver glue.

[0056] Wire bonding is carried out using a gold wire bonder. The ultrasonic power is 80 mW, the bonding pressure is 20 g, and the bonding time is 10 ms.

[0057] A fluorine-containing silicone resin is filled to a height of 0.4 mm, covering an 8 mm × 8 mm quartz glass cover plate. The ultraviolet curing condition is irradiation with a 365 nm ultraviolet lamp for 10 minutes.

[0058] A copper heat sink with a size of 15 mm × 15 mm is installed, and the first lens silicone with a thermal conductivity of 6 W / (m·K) is applied to form a number of first hemispherical lenses. The first hemispherical lenses are hemispherical convex lens structures; a first silicone layer is coated on the upper part of the first hemispherical lenses, and a second lens silicone is coated on the first silicone layer to form a number of second hemispherical lenses. The second hemispherical lenses are hemispherical convex lens structures; a second silicone layer is coated on the upper part of the second hemispherical lenses; wherein, at least one of the second hemispherical lenses and the second silicone layer has phosphor.

[0059] The test results show that the light extraction efficiency is increased by 28%. After continuous operation for 2000 hours, the chip temperature rise does not exceed 12 °C, and the device reliability is good.

[0060] It can be seen from the above examples that the packaging process of the deep ultraviolet LED device of the present invention can effectively improve the light extraction efficiency and heat dissipation performance, simplify the process and reduce the cost, and has good application prospects and market value.

[0061] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep ultraviolet LED device packaging process, characterized in that: The following steps are involved: Step 1: Chip pretreatment: Clean and surface treat the deep ultraviolet LED chip to remove impurities and pollutants on the surface of the deep ultraviolet LED chip; Step 2: Package substrate selection and processing: A ceramic substrate with high thermal conductivity is selected as the packaging substrate, and the surface of the packaging substrate is metallized; Step 3: Die bonding and bonding: Die bonding: Use silver glue to fix the pre-treated deep ultraviolet LED chip to the predetermined position on the packaging substrate; Wire bonding: Using the gold wire bonding process, the electrodes of the deep ultraviolet LED chip are connected to the positive and negative regions of the corresponding packaging substrate through gold wires; Step 4: Filling and sealing: A silicone material with high light transmittance, low refractive index and good UV resistance is filled around the deep ultraviolet LED chip, the filling height is higher than the chip, and then a quartz glass cover plate is covered on it, and the quartz glass cover plate is sealed and fixed to the packaging substrate by ultraviolet curing glue; Step 5: Heat dissipation structure optimization: A metal heat sink is installed on the back of the packaging substrate, and a first lens silica gel is coated between the metal heat sink and the packaging substrate to form a plurality of first hemispherical lenses, wherein the first hemispherical lenses are hemispherical convex transparent structures.

2. A deep ultraviolet LED device packaging process according to claim 1, characterized in that: In step one, the chip pretreatment includes using plasma cleaning technology to treat the surface of the deep ultraviolet LED chip with inert gas plasma for 5-10 minutes under the conditions of a vacuum degree of 10-100 Pa and a radio frequency power of 200-500 W; wherein the inert gas is a mixture of one or more of argon and helium.

3. A deep ultraviolet LED device packaging process according to claim 1, characterized in that: In step 2, the ceramic substrate with high thermal conductivity is an aluminum nitride substrate or an aluminum oxide substrate; the metallization treatment is to deposit a copper or silver metal layer on the surface of the packaging substrate by magnetron sputtering or chemical plating, and the thickness of the metal layer is 1-3 μm.

4. The deep ultraviolet LED device packaging process according to claim 1, characterized in that: In step three, in the solid crystal step, the curing temperature of the silver glue is 160-170°C, and the curing time is 22-28 minutes; in the wire bonding step, the bonding parameters of the gold wire bonding process are: ultrasonic power 50-80mW, bonding pressure 10-20g, bonding time 5-10ms, and the diameter of the gold wire is 15-25μm, and the packaging substrate is divided into a positive electrode region and a negative electrode region, and a plurality of packaging substrates are arranged in an array in the opposite order of the positive and negative electrodes of adjacent packaging substrates, wherein the positive electrode region and the negative electrode region of the packaging substrate are both provided with a metal eutectic bonding layer, and the deep ultraviolet LED chip is electrically connected to the positive electrode region and the negative electrode region of the packaging substrate through the metal eutectic bonding layer.

5. The deep ultraviolet LED device packaging process according to claim 1, characterized in that: In step 4, the organic silicon material is a fluorine-containing organic silicon resin, whose refractive index is between 1.3-1.4 and whose light transmittance is above 90%; the ultraviolet curing condition is irradiation under an ultraviolet lamp with a wavelength of 365nm for 5-10 minutes.

6. The deep ultraviolet LED device packaging process according to claim 1, characterized in that: In step five, the metal heat sink is made of aluminum or copper, and has a thickness of 1-3 mm; and the thermal conductivity of the first lens silicone is not less than 5 W / (m·K).

7. A deep ultraviolet LED device packaging process according to claim 6, characterized in that: In step 5, a first silicone layer is coated on the upper part of the first hemispherical lens, and a second lens silicone is coated on the first silicone layer to form a plurality of second hemispherical lenses, wherein the second hemispherical lenses are hemispherical convex transparent structures; A second silicone layer is coated on the upper part of the second hemispherical lens; wherein at least one of the second hemispherical lens and the second silicone layer has fluorescent powder.

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