CN110310947A - A UV LED all-inorganic packaging structure with prompt function - Google Patents

Abstract

The invention relates to the technical field of LED packaging, and provides a UV LED all-inorganic packaging structure with a prompt function, comprising a substrate, a UVA chip, a UVC chip and a cover, wherein the UVA chip and the UVC chip are arranged on the substrate, so that the The cover includes a metal frame fixed on the substrate and surrounding the UVA chip and the UVC chip, and a cover plate arranged on the upper end face of the metal frame, and the cover plate is suspended above the UVA chip and the UVC chip. . The packaging structure of the present invention can play a prompting role, allowing users to receive visible light signals, and can also increase the efficacy of packaging lamp beads, so that it can simultaneously have the functions of UVC lamp beads sterilization and disinfection, UVA lamp beads ultraviolet curing, air purification and other functions, and at the same time , The use of all-inorganic packaging structure has high stability and long life.

Description

A UV LED all-inorganic packaging structure with prompt function

technical field

The invention relates to the field of LED packaging, in particular to a UV LED all-inorganic packaging structure with a prompt function.

Background technique

The emerging ultraviolet light source adopts the LED light-emitting principle, called "UV LED". Compared with the traditional mercury lamp ultraviolet light source, it has the following advantages: 1. The ultraviolet LED is an all-solid-state lighting device, with stable mechanical structure, portability, impact resistance, and working voltage. Small, and does not require complex drive circuits; 2. The UV LED has a high response rate and is ready to use, without complex operations such as preheating, and is easy to use; 3. The traditional mercury lamp emits multiple spectral lines, and the UV LED has a single luminous peak and a luminous wavelength. Continuously adjustable; 4. The UV LED material does not contain substances that are harmful to the environment. At the same time, the UV LED saves up to 70% of energy, which is a real environment-friendly and energy-saving light source; 5. The UV LED has a life span of more than 5,000 hours, far exceeding mercury lamp life. Therefore, UV LED is gradually replacing the traditional mercury lamp UV light source in the market share.

UV LED includes all electromagnetic radiation wavelengths between 200nm and 400nm. The application market can currently be divided into UVA (320nm～400nm, also known as "long-wave ultraviolet") according to its emission wavelength. It is used in ultraviolet curing, printing, ultraviolet air purification, etc. ; UVB (275nm ~ 320nm, also known as "medium wave ultraviolet"), used in ultraviolet phototherapy, anti-counterfeiting detection, plant growth, etc.; UVC (200nm ~ 275nm, also known as "short wave ultraviolet") band, widely used in sterilization and disinfection , medical, special equipment, etc.

Among the ultraviolet rays of various wavelengths, only short-wave ultraviolet UVC has the effect of sterilization and disinfection, which belongs to the pure physical disinfection method. The sterilization effect of UVC on bacteria and viruses is generally completed within a few seconds, which occurs almost instantaneously. Therefore, the application prospect of UVC in the sterilization and disinfection market is bright. Since the wavelength of the UVC LED is in the invisible light band, the user cannot see any light when using the UVC LED, so it will cause a confusion to the user whether the UVC LED is working normally. At the same time, the current application classification of UV LED packaging products is clear, and a single product has only one function. For example, UVC products only have sterilization functions, UVA products only have UV curing and air purification functions, and lack UV function integration products.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides a UV LED all-inorganic packaging structure with a prompt function, including a substrate, a UVA chip, a UVC chip and a cover, the UVA chip and the UVC chip are arranged on the substrate, and the The cover includes a metal frame fixed on the substrate and surrounding the UVA chip and the UVC chip, and a cover plate arranged on the upper end surface of the metal frame, and the cover plate is suspended above the UVA chip and the UVC chip.

Preferably, pairs of through holes are formed through the substrate, and the pairs of through holes are filled with conductive metal respectively, and corresponding pad pairs are formed on the upper surface of the substrate and electrode pairs are formed on the lower surface, so The UVA chip and the UVC chip are respectively disposed in the middle of the pad pair and electrically connected with them, and placed on the substrate.

More preferably, the pad pair includes a pad pair one and a pad pair two separated from each other, and the shape of the pad pair one is to continuously shrink outward from a side close to the UVA chip and the UVC chip. , the shape of the pad pair 2 is to gradually expand outward from the side close to the UVA chip and the UVC chip; the electrode pair includes an electrode pair 1 and an electrode pair 2 corresponding to the pad pair. .

More preferably, the UVC chip is disposed between and electrically connected to the first pair of pads, and the UVA chip is disposed between and electrically connected to the second pair of pads.

Preferably, the UVA chip is a front-mounted UVA chip, a vertical UVA chip or a flip-chip UVA chip, and the UVC chip is a front-mounted UVC chip, a vertical UVC chip or a flip-chip UVC chip.

Preferably, it also includes a thermoelectric separation layer disposed under the substrate.

Preferably, it also includes a Zener tube disposed on the substrate and connected in parallel with the UVC chip.

Preferably, the cover plate is a quartz glass cover plate, and a first metal layer and a second metal layer are sequentially provided between the quartz glass cover plate and the metal frame.

Preferably, the first metal layer is Kovar alloy, and the second metal layer is gold or gold-tin alloy.

Preferably, the thickness of the first metal layer is 10 μm˜200 μm, and the thickness of the second metal layer is 5 μm˜50 μm.

The UV LED all-inorganic encapsulation structure with the prompting function of the present invention can emit not only "short-wave ultraviolet rays" with a wavelength of 200nm-275nm, but also "long-wave ultraviolet rays" with a wavelength of 320nm-400nm, and the long-wave ultraviolet rays emitted by the encapsulation structure are visible The wavelength band can play a prompting role when using it, allowing users to have a perceptual understanding, and at the same time, it can increase the efficacy of the packaged lamp beads, so that it can simultaneously have sterilization, disinfection functions, UV curing, and air purification functions.

In addition, the UV LED packaging structure of the present invention adopts an all-inorganic packaging method, which can effectively solve the aging and embrittlement of materials caused by ultraviolet high-energy radiation, the thermal stress caused by the large thermal expansion coefficient of organic materials, and the moisture and gas caused by moisture and oxygen permeability of organic materials. To solve problems such as poor density, enhance the stability of the UV LED packaging structure and improve the working life of the UV LED.

Description of drawings

The top view of the UV LED all-inorganic packaging structure with the prompt function in the embodiment 1 of FIG. 1;

Figure 2 is a bottom view of the UV LED all-inorganic encapsulation structure with a prompt function in Embodiments 1 and 3;

Figure 3 is a cross-sectional view of the A-A plane in Figure 1;

Figure 4 is a cross-sectional view of the B-B plane in Figure 1;

Figure 5 is a top view of the UV LED all-inorganic packaging structure with a prompt function in Example 2;

Figure 6 bottom view of the UV LED all-inorganic packaging structure with prompt function in Example 2;

FIG. 7 is a top view of the UV LED all-inorganic packaging structure with the prompt function in the third embodiment.

Among them, 1-substrate; 2-metal frame; 3-pad to one; 4-pad to two; 5-positive UVA chip; 6-conductive wire; 7-flip-chip UVC chip; 8-flip-chip Zener tube 9-cover plate; 901-first metal layer; 902-second metal layer; 10-electrode pair one; 11-thermoelectric separation structure; 12-electrode pair two; 13-metal connection layer; 14-pad pair three ; 15- Flip-chip UVA chip; 16- Electrode pair three; 17- Front-mounted UVC chip; 18- Front-mounted Zener tube.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1:

The substrate 1 is an aluminum oxide substrate, which is pre-treated and cleaned, and then two through-hole pairs are drilled on the aluminum oxide substrate by laser, and the two through-hole pairs are arranged side by side, and the conductive metal is used to fill the through holes by sputtering. Yes, the conductive metal is copper, and a conductive metal layer with a thickness of 10 μm is formed on the upper and lower surfaces of the substrate.

As shown in FIG. 1 and FIG. 2 , a photoresist is arranged to cover the upper and lower surfaces of the substrate 1 by means of yellow light lithography. After the photoresist covers the substrate 1 , exposure, development, etching, and film removal are performed. The uncovered area on the upper surface forms pad pair 1 3 and pad pair 2 4, the area below pad pair 1 3 and the uncovered area on the lower surface of substrate 1 forms electrode pair 1 10, below pad pair 2 4, the substrate 1. The uncovered area of the lower surface forms the second electrode pair 12, and the thermoelectric separation structure 11 is formed between the first electrode pair 10 and the second electrode pair 12. The shape of the pair of pads 1 3 is continuously shrinking from the side close to the UVA chip and the UVC chip, in a symmetrical "L" shape, and the shape of the pair of pads 4 is from the side close to the UVC chip. One side of the UVA chip and the UVC chip gradually expands outwards, forming a symmetrical "7" shape. Then, a gold layer with a thickness of 5 μm is electroplated on the substrate 1, which can effectively prevent copper oxidation.

Use a glue dispenser to place the epoxy resin solidification glue on the blank area in the middle of the pad pair 24, then press the UVA chip on the epoxy resin solidification glue, bake at 150 ° C for 1 hour, the UVA chip is Can be fixed on the base plate. One end of the conductive wire 6 is connected to the electrode of the UVA chip, and the other end is connected to the pad pair 2 4 , and the connection is fixed by the ultrasonic hot pressing method. The conductive wires 6 are gold wires, silver gold-plated alloy wires, copper palladium-plated alloy wires, silver wires or aluminum wires. The UVA chip is a full UVA chip 5.

Put the normal temperature solder paste on the pad pair one 3, place the UVC chip and the Zener tube on the solder paste in parallel, then place the substrate 1 on the heating table to heat, the temperature is 200 ℃, the time is 8s ~ 10s, and the substrate is removed After 1, it is cooled naturally, and the UVC chip and the substrate 1 can be fixed. The Zener tube is connected in parallel with the UVC chip to prevent electrostatic breakdown. The UVC chip is a flip-chip UVC chip 7 , and the Zener tube is a flip-chip Zener tube 8 .

The metal frame 2 is made of copper or aluminum. The inner side of the metal frame 2 is provided with a groove near the upper end face, and the outer surface of the metal frame 2 is electroplated with a gold-tin layer with a thickness of 50 μm; The tin eutectic sheet solder is heated in a _N2 or Ar protective atmosphere to melt it, and then pressure is applied to cool it naturally, so that the metal frame 2 is combined with the substrate 1 .

As shown in Figure 3, take the rectangular plane quartz glass as the cover plate 9, and sputter the first metal layer 901 of 4J29 with a thickness of 10 μm around the edge of the lower surface. The first metal layer is a Kovar alloy. A gold layer with a thickness of 5 μm is re-plated on 901 as the second metal layer 902 . The first metal layer 901 is Kovar 4J29, the expansion coefficient at 0-300°C is (4.7-5.5)×10 ^-6 /K, the expansion coefficient of quartz glass is 0.55×10 ^-6 /K, and the expansion coefficient of gold is 14.2×10 ^-6 /K, the expansion coefficient of Kovar alloy is between quartz glass and gold or gold-tin. Using Kovar alloy as the metal connecting quartz glass and gold can avoid thermal stress problems. Quartz glass has a small expansion coefficient and is not easy to generate stress, making the package structure more stable; quartz glass has extremely low moisture permeability and oxygen permeability, making the package structure more airtight.

The surrounding edges of the cover plate 9 are embedded in the grooves of the metal frame 2, and the flux is placed on the grooves of the metal frame 2, and the gold layer 902 on the surrounding edges of the lower surface of the cover plate 9 is aligned and placed on the grooves of the metal frame 2. The frame and the cover plate are put into the eutectic furnace together and heated in a _N2 or Ar protective atmosphere, and the eutectic reaction is carried out, so that the cover plate 9 is suspended above the UVA chip, the UVC chip and the Zener tube, and the upper surface of the cover plate 9 is suspended. Be flush with the top surface of the metal frame 2. That is, the package structure of Embodiment 1 is obtained.

In this embodiment, the thermoelectric separation structure 11 is used to enhance the heat dissipation of the chip and prevent the chip from failing due to high temperature. In the UV LED all-inorganic packaging structure of this embodiment, the UVA pads and the UVC pads are respectively connected to different electrodes, and the pads are separately arranged to realize independent control, and the packaging structure of the present invention can be used in different scenarios and different needs. The shape design of pad pair 1 3 and pad pair 2 4 can increase the pad area on the substrate to a certain extent. The pad is made of metal material, which has a certain reflective performance compared to the substrate. The design of this embodiment can improve the The light extraction performance of the device. More importantly, since the UVA chip is often wider, the UVA pad area on the ceramic substrate is relatively narrow, which increases the difficulty of fixing the conductive wire on the one hand, and adversely affects the electrical properties of the UVA pad on the other hand. The structure of the pad pair 2 and 4 in this embodiment is wide outside, which makes it easier to fix the conductive wire and the UVA pad, increases the capacitance, and improves the stability of the device. It can meet the packaging of multiple UVC chips. Fixing the Zener tube and UVC chip in parallel on the pad pair one 3 can play the role of voltage regulation and anti-static breakdown, and protect the UVC chip.

Example 2

As shown in Figure 5, the substrate 1 is an aluminum nitride substrate, which is pre-treated and cleaned, and then a through hole pair is drilled on the aluminum nitride substrate by deep reactive ion etching, and the conductive metal is filled with the conductive metal by sputtering. For the hole pair, the conductive metal is copper, and a conductive metal layer with a thickness of 1000 μm is formed on the upper and lower surfaces of the substrate.

As shown in FIG. 5 and FIG. 6 , a photoresist is arranged to cover the upper surface and the lower surface of the substrate 1 by means of yellow light lithography. After the photoresist covers the substrate 1, exposure, development, etching, and film removal are performed. The uncovered area on the upper surface forms the pad pair 3 14 , the area below the pad pair and the uncovered lower surface of the substrate forms the electrode pair 3 16 , and the thermoelectric separation structure 11 is formed between the electrode pairs. A gold layer with a thickness of 50 μm was then electroplated on the substrate 1 to prevent copper oxidation.

In the pair of UVA chip, UVC chip, Zener tube and pad, put gold-tin eutectic sheet solder, heat it in _N2 or Ar protective atmosphere to melt it, then apply pressure and cool it naturally to make the UVA chip, UVC The chip and the Zener are connected in parallel on the substrate, the UVA chip is a flip-chip UVA chip 15 , the UVC chip is a flip-chip UVC chip 7 , and the Zener is a flip-chip Zener 8 .

Get the rectangular plane quartz glass as the cover plate 9, be the first metal layer of 4J34 with the trade mark of 200 μm in its lower surface surrounding edge sputtering thickness, the first metal layer is Kovar alloy, and the thickness of electroplating on the first metal layer is A 50 μm gold-tin layer was used as the second metal layer. Among them, the first metal layer is Kovar alloy 4J34, the expansion coefficient at 0 ~ 300 ℃ is (4.7 ~ 5.5) × 10 ^-6 /K, the expansion coefficient of quartz glass is 0.55 × 10 ^-6 /K, the expansion coefficient of gold tin is 16 ×10 ^-6 /K, the expansion coefficient of Kovar alloy is between quartz glass and gold-tin. Using Kovar alloy as the metal connecting quartz glass and gold can avoid thermal stress problems. Quartz glass has a small expansion coefficient and is not easy to generate stress, making the package structure more stable; quartz glass has extremely low moisture permeability and oxygen permeability, making the package structure more airtight.

In this embodiment, the UVA chip, the UVC chip, and the zener are connected in parallel on the same pad pair 3 14, and the three are on the same switch, which can play the role of voltage regulation and anti-static breakdown, and protect the UVC chip and the UVA chip. The visible light emitted by the UVA chip can play a prompting role, and the package structure of this embodiment has both the functions of ultraviolet curing and air purification.

Example 3

As shown in FIG. 7 , the substrate 1 is an aluminum nitride substrate, which is cleaned by pre-treatment, and then two through-hole pairs are drilled on the aluminum nitride substrate by deep reactive ion etching, and the two through-hole pairs are arranged side by side. The through-hole pair is filled with conductive metal by sputtering, and the conductive metal is copper, and a conductive metal layer with a thickness of 650 μm is formed on the upper and lower surfaces of the substrate 1 respectively.

As shown in FIG. 2 , a photoresist is arranged to cover the upper surface and the lower surface of the substrate 1 by means of yellow light lithography. After the photoresist covers the substrate 1 , exposure, development, etching, and film removal are performed. The uncovered area on the upper surface forms pad pair 1 3 and pad pair 2 4, the area below pad pair 1 3 and the uncovered area on the lower surface of the substrate forms electrode pair 1 10, below pad pair 2 4, substrate 1 The uncovered area of the lower surface forms the second electrode pair 12 , and the thermoelectric separation structure 11 is formed between the first electrode pair 10 and the second electrode pair 12 . The pad pair one 3 and the pad pair two 4 are both rectangular in shape. Then a gold layer with a thickness of 10 μm is electroplated on the substrate, which can effectively prevent copper oxidation. Among them, the thermoelectric separation structure enhances the heat dissipation of the chip and prevents the chip from failing due to high temperature.

Use a glue dispenser to spot the silica gel on the blank area in the middle of the pad pair 24, then press the UVA chip on the silica gel, bake it at 150°C for 1 hour, and the UVA chip can be fixed on the substrate 1. One end of the conductive wire 6 is connected to the electrode of the UVA chip, and the other end is connected to the pad pair 2 4 , and the connection is fixed by the ultrasonic hot pressing method. The UVA chip is the full UVA chip 15. In the same way, the UVC chip and the Zener tube are electrically connected to the pad pair-3. The UVC chip is the UVC chip 17 that is installed, and the Zener tube is the Zener tube 18 that is installed.

The metal frame 2 is made of copper or aluminum. The inner side of the metal frame 2 is provided with a groove near the upper end face. The outer surface of the metal frame 2 is electroplated with a gold-tin layer with a thickness of 10 μm. In the low temperature and high pressure equipment, the maximum temperature of heating is 300° C., and the hot pressing is performed for 40 min to 70 min, so that the metal frame 2 is combined with the substrate 1 .

Get the rectangular plane quartz glass as the cover plate 9, be the first metal layer of 4J36 with the brand name of 50 μm in its lower surface surrounding edge sputtering thickness, the first metal layer is Kovar alloy, and the thickness of electroplating on the first metal layer is A 10 μm gold layer was used as the second metal layer. The surrounding edges of the cover plate 9 are embedded in the grooves of the metal frame 2, and then placed in the hot pressing equipment, heated to a maximum temperature of 300 ° C, and pressurized for 40min-70min, so that the cover plate 9 is suspended in the UVA chip 5, UVC chip 7 and homogeneous. Above the nanotube 8 , and the upper surface of the cover plate 9 is flush with the upper surface of the metal frame 2 .

In this embodiment, the UVA chip, the UVC chip, and the zener are all positive-mounted chips, which can save production costs. Fixing the Zener tube and UVC chip in parallel on the pad pair one 3 can play the role of voltage regulation and anti-static breakdown, and protect the UVC chip.

Compared with the prior art, the inorganic encapsulation structure of the UV LED provided by the present invention can not only emit "short-wave ultraviolet rays" with a wavelength of 200 nm to 275 nm, but also can emit "long-wave ultraviolet rays" with a wavelength of 320 nm to 400 nm. The long-wave ultraviolet light emitted by the package structure is in the visible band, which can play a prompting role when using it, allowing users to receive visible light signals and generate perceptual knowledge. Curing, air purification function.

In addition, the UV LED packaging structure of the present invention adopts an all-inorganic packaging method, which can effectively solve the aging and embrittlement of materials caused by ultraviolet high-energy radiation, the thermal stress caused by the large thermal expansion coefficient of organic materials, and the moisture and gas caused by moisture and oxygen permeability of organic materials. To solve problems such as poor density, enhance the stability of the UV LED packaging structure and improve the working life of the UV LED.

The above are only several preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A UV LED all-inorganic packaging structure with a prompt function is characterized in that, comprising a substrate, a UVA chip, a UVC chip and a cover, the UVA chip and the UVC chip are arranged on the substrate, and the cover includes A metal frame fixed on the substrate and surrounding the UVA chip and the UVC chip, and a cover plate arranged on the upper end face of the metal frame, the cover plate is suspended above the UVA chip and the UVC chip. 2 . The UV LED all-inorganic packaging structure with a prompt function according to claim 1 , wherein a pair of through holes is formed through the substrate, and the pair of through holes are filled with conductive metal respectively, and the holes are filled with conductive metal. 3 . A pad pair is formed on the upper surface of the substrate, and an electrode pair is formed on the lower surface. The UVA chip and the UVC chip are respectively arranged in the middle of the pad pair and electrically connected to it, placed on the on the substrate. 3 . The UV LED all-inorganic packaging structure with a prompt function according to claim 2 , wherein the pad pair comprises a pad pair one and a pad pair two separated from each other, and the pad pair The shape of one is gradually shrinking from the side close to the UVA chip and the UVC chip, and the shape of the pair of pads is gradually expanding from the side close to the UVA chip and the UVC chip. ; The electrode pair includes an electrode pair 1 and an electrode pair 2 corresponding to the pad pair. 4 . The UV LED all-inorganic packaging structure with a prompt function according to claim 3 , wherein the UVC chip is disposed between the pair of pads and is electrically connected to it, and the UVA chip is 4. 5 . It is arranged between the two pad pairs and is electrically connected to them. 5. The UV LED all-inorganic packaging structure with a prompt function according to claim 4, wherein the UVA chip is a positive UVA chip, a vertical UVA chip, or a flip-chip UVA chip, and the UVC chip is Front mount UVC chip, vertical UVC chip or flip-chip UVC chip. 6 . The UV LED all-inorganic packaging structure with prompt function according to claim 1 , further comprising a thermoelectric separation layer disposed under the substrate. 7 . 7 . The UV LED all-inorganic packaging structure with prompt function according to claim 1 , further comprising a Zener tube disposed on the substrate and connected in parallel with the UVC chip. 8 . 8. The UV LED all-inorganic packaging structure with a prompt function according to claim 1, wherein the cover plate is a quartz glass cover plate, and a second plate is arranged between the quartz glass cover plate and the metal frame in sequence. a metal layer and a second metal layer. 9 . The UV LED all-inorganic packaging structure with prompt function according to claim 8 , wherein the first metal layer is Kovar alloy, and the second metal layer is gold or gold-tin alloy. 10 . 10 . The UV LED all-inorganic packaging structure with prompt function according to claim 9 , wherein the thickness of the first metal layer is 10 μm˜200 μm, and the thickness of the second metal layer is 5 μm˜50 μm. 11 .