CN210110761U

CN210110761U - UV LED all-inorganic packaging structure

Info

Publication number: CN210110761U
Application number: CN201921161771.3U
Authority: CN
Inventors: 孙雷蒙; 杨丹; 刘芳; 李坤
Original assignee: Wick (wuhan) Technology Co Ltd
Current assignee: Wick (wuhan) Technology Co Ltd
Priority date: 2019-07-23
Filing date: 2019-07-23
Publication date: 2020-02-21
Anticipated expiration: 2029-07-23

Abstract

The utility model provides a full inorganic packaging structure of UV LED, including base plate, chip, closing cap, the chip set up in on the base plate, the closing cap includes metal frame, apron, the metal frame inboard is provided with the recess, imbed all around of apron in order to make in the recess the apron is unsettled in the top of chip, the metal frame set up in on the base plate, the apron upper surface with metal frame upper surface parallel and level. And a first metal layer and a second metal layer are sequentially arranged between the cover plate and the metal frame. The utility model provides a UV LED all inorganic packaging structure ultraviolet resistance can the reinforce, coefficient of thermal expansion is little, the gas tightness is good, stability is high, long service life.

Description

UV LED all-inorganic packaging structure

Technical Field

The utility model belongs to the technical field of the LED encapsulation, especially, relate to a full inorganic packaging structure of UV LED.

Background

The traditional ultraviolet light source (UV) adopts mercury vapor discharge to generate ultraviolet rays by utilizing the excitation state of mercury, and has the defects of high power consumption, large heat productivity, short service life, slow reaction, potential safety hazard and the like. The emerging ultraviolet light source adopts the LED light-emitting principle, is called as 'UV LED', and has the following advantages compared with the traditional mercury lamp ultraviolet light source: 1. the ultraviolet LED is an all-solid-state lighting device, has a stable mechanical structure, is portable, is impact-resistant, has a small working voltage, and does not need a complex driving circuit; 2. the ultraviolet LED is ready to use when the response rate is high, complex operations such as preheating and the like are not needed, and the use is convenient; 3. the traditional mercury lamp emits light in multiple spectral lines, the ultraviolet LED has a single light-emitting peak, and the light-emitting wavelength is continuously adjustable; 4. the ultraviolet LED material does not contain substances harmful to the environment, and meanwhile, the ultraviolet LED saves energy by up to 70 percent, thereby being a real environment-friendly energy-saving light source; 5. the service life of the ultraviolet LED is more than 5000 hours, which far exceeds the service life of a mercury lamp. The UV LED includes all electromagnetic radiation wavelengths between 100nm and 420nm, and the application market can be currently divided into UVA (320nm to 420nm, also referred to as "long-wave ultraviolet"), UVB (275nm to 320nm, also referred to as "medium-wave ultraviolet") and UVC (100nm to 275nm, also referred to as "short-wave ultraviolet") bands according to the emission wavelength thereof, and is widely used in medical applications, printing, ultraviolet air purification, high-resolution optical applications, phosphor reflection, UV gel curing, special lighting, and the like.

The use of UV LEDs in real environments often faces a number of challenges, with reliability issues being particularly acute. To improve the reliability of UV LEDs, it is a very effective way to improve from the packaging structure. At present, low-power medium-low end UV LED chips such as ultraviolet sterilization, ultraviolet curing and the like are mainly packaged by adopting a visible light LED packaging mode, namely, resin organic materials are adopted for packaging, and the organic materials have the characteristics of poor UV resistance, large thermal expansion coefficient and high moisture and oxygen permeability, so that the defects of ultraviolet radiation induced colloid yellowing light source attenuation, thermal stress embrittlement and moisture stress impurity invasion can be caused, and the reliability of the UVLED can be greatly reduced.

The UV LED chip for high power and high end applications, such as medical instruments, printing, high resolution optical applications, etc., must have high reliability and long service life due to its high illumination intensity and strict requirements. In order to solve the problem of high-energy radiation of the UV LED, organic materials are reduced or even completely eliminated during packaging, so that the problems caused by the organic materials are reduced or avoided. Therefore, how to adopt inorganic materials to replace organic materials to carry out all inorganic packaging of the UV LED to improve the reliability, the luminous efficiency and the service life of the chip is worth researching.

Disclosure of Invention

In order to solve the problems, the utility model aims at providing a UV LED all inorganic packaging structure of higher gas tightness, stability and working life, including base plate, chip, closing cap, the chip set up in on the base plate, the closing cap includes metal frame, apron, the metal frame inboard is provided with the recess, the both ends embedding of apron in so that the apron is unsettled in the top of chip, the metal frame set up in on the base plate, the apron upper surface with metal frame upper surface parallel and level.

Preferably, a first metal layer and a second metal layer are sequentially arranged between the cover plate and the metal frame.

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

Preferably, the thickness of the first metal layer is 5-100 μm, and the thickness of the second metal layer is 5-50 μm.

Preferably, a through hole is formed in the substrate, a pad is arranged on the upper surface of the substrate corresponding to the through hole, a second electrode is arranged on the lower surface of the substrate corresponding to the through hole, copper is filled in the through hole, so that the pad is electrically connected with the second electrode through the copper, and the chip is arranged on the pad through the first electrode, so that the chip is electrically connected with the second electrode.

Preferably, the second electrode is a copper layer and a gold layer in sequence from top to bottom, and the area of the copper layer is larger than that of the gold layer.

Preferably, the chips are single or multiple.

Preferably, the chip is a flip LED chip, a vertical LED chip or a front-mounted LED chip.

Preferably, a gold layer and a copper layer are sequentially arranged between the metal frame and the substrate.

Preferably, the metal frame material is copper or aluminum, the substrate material is aluminum oxide or aluminum nitride, and the cover plate is a quartz glass cover plate.

The utility model discloses an encapsulation structure possesses following beneficial effect:

(1) the UV LED all-inorganic packaging structure of the utility model adopts inorganic materials with strong ultraviolet resistance, small thermal expansion coefficient and good air tightness;

(2) the connection between the whole structure adopts a metal bonding mode, the bonding strength between materials is high, and the mechanical property and the sealing property are good.

The utility model discloses a UV LED all-inorganic packaging structure can effectively solve the ageing embrittlement of the material that ultraviolet high energy radiation produced, and organic material coefficient of thermal expansion is big and the thermal stress that produces, and organic material drenches the wet stress that oxygen permeation caused and gas tightness subalternation problem, reinforcing UV LED packaging structure's stability improves UV LED's working life.

Drawings

FIG. 1 is a cross-sectional view of an all inorganic package structure for a UV LED;

FIG. 2 is a top view of an all inorganic package structure for a UV LED that does not include a cover plate;

FIG. 3 is a bottom view of an all inorganic packaging structure for the UV LED;

FIG. 4 is a partial view of a quartz glass cover plate and a first metal connection layer;

wherein, 1 is a cover plate, 2 is a metal frame, 3 is a metal connecting layer, 31 is a kovar alloy layer, 32 is a gold layer or a gold-tin layer, 4 is a chip, 5 is a bonding pad, 6 is a first electrode, 7 is a substrate, 8 is a thermoelectric separation structure, 9 is a second electrode, 901 is a copper layer, and 902 is a gold layer.

Detailed Description

In order to make the technical problem, technical solution and advantageous effects to be solved by the present invention more clearly understood, the following description is made in conjunction with the accompanying drawings and embodiments to explain the present invention in further detail. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

Example 1:

an all-inorganic packaging structure of a UV LED is shown in figure 1 and comprises a quartz glass cover plate 1, a metal frame 2, a metal connecting layer 3, a UV LED flip chip 4, a bonding pad 5, a first electrode 6, a ceramic substrate 7, a thermoelectric separation structure 8 and a second electrode 9. The ceramic substrate is made of aluminum nitride, two through holes are formed in the ceramic substrate 7 in a laser drilling mode, copper is filled in the through holes in a sputtering mode, copper layers with the thickness of 10 mu m are formed on the upper surface and the lower surface of the ceramic substrate respectively, a photoresist covers the upper surface and the lower surface of the ceramic substrate in a yellow light lithography mode, gold layers with the thickness of 5 mu m are exposed, developed, etched, stripped and electroplated, a bonding pad 5 is formed on the upper surface corresponding to each through hole, a second electrode 9 is formed on the corresponding lower surface, and the bonding pad 5 is electrically connected with the second electrode 9 through copper.

And fixing the first electrode 6 below the single UV LED flip chip 4 on the upper surface of the bonding pad in a eutectic soldering mode so as to electrically connect the UV LED flip chip 4 with the second electrode 9. The metal frame 2 material is copper, adopts the mode of eutectic bonding to weld gold layer and copper layer between metal frame to the base plate in proper order, and metal frame 2 inboard is provided with the recess, and the embedding of the both ends of quartz glass apron 1 in order to make quartz glass apron 1 unsettled in the top of

UV LED chip

4, 1 upper surface of quartz glass apron and 2 upper surface parallel and level of metal frame. A gold layer with the thickness of 5 mu m and a kovar alloy layer with the thickness of 5 mu m are electroplated between the metal frame and the quartz glass cover plate in sequence.

As shown in fig. 3, the second electrode 9 includes a copper layer 901 and a gold layer 902, and the copper layer 901 is disposed between the gold layer 902 and the ceramic substrate 7 and has an area larger than that of the gold layer 902.

In addition, as shown in fig. 4, the metal connection layer 3 includes a kovar alloy layer 31 and a gold layer 32, and the kovar alloy layer 31 is located above the gold layer 32 and is connected to the quartz glass cover plate.

The specific embodiment of the utility model adopts kovar alloy as 4J36 mark, 0-300 ℃ expansion coefficient (5.5-6.5) x 10^-6K, coefficient of expansion of the quartz glass 0.55X 10^-6K, coefficient of expansion of gold 14.2X 10^-6and/K. The expansion coefficient of the kovar alloy is between that of quartz glass and gold, and the kovar alloy is used as metal for connecting the quartz glass and the gold, so that the problem of thermal stress can be avoided, and the reliability of the packaging structure is improved.

Example 2

An all inorganic packaging structure of a UV LED, as shown in figure 1, figure 2 and figure 3, comprises a quartz glass cover plate 1, a metal frame 2, a metal connecting layer 3, a UV LED flip chip 4, a bonding pad 5, a first electrode 6, a ceramic substrate 7, a thermoelectric separation structure 8 and a second electrode 9. The ceramic substrate is made of aluminum nitride, two through holes are formed in the ceramic substrate 7 in a laser drilling mode, copper is filled in the through holes in a sputtering mode, copper layers with the thickness of 650 mu m are respectively formed on the upper surface and the lower surface of the ceramic substrate, photoresist is covered on the upper surface and the lower surface of the ceramic substrate in a yellow light lithography mode, gold-tin layers with the thickness of 10 mu m are exposed, developed, etched, stripped and electroplated, a bonding pad 5 is formed on the upper surface corresponding to each through hole, a second electrode 9 is formed on the corresponding lower surface, and the bonding pad 5 is electrically connected with the second electrode 9 through copper.

And fixing the first electrodes 6 below the four UV LED flip chips 4 on the upper surface of the bonding pad in an eutectic soldering mode so that the four UV LED flip chips 4 are connected in parallel and are electrically connected with the second electrodes 9. The metal frame 2 material is copper, adopts the mode of eutectic bonding to weld gold tin layer and copper layer between metal frame to the base plate in proper order, and metal frame 2 inboard is provided with the recess, and the embedding of the both ends of quartz glass apron 1 in order to make quartz glass apron 1 is unsettled in the top of four

UV LED chips

4, 1 upper surface of quartz glass apron and 2 upper surface parallel and level of metal frame. A gold-tin layer with the thickness of 10 mu m and a kovar alloy layer with the thickness of 10 mu m are electroplated between the metal frame and the quartz glass cover plate in sequence.

As shown in fig. 3, the second electrode 9 includes a copper layer 901 and a gold-tin layer 902, and the copper layer 901 is disposed between the gold-tin layer 902 and the ceramic substrate 7 and has an area larger than that of the gold-tin layer 902.

In addition, as shown in fig. 4, the metal connection layer 3 includes a kovar layer 31 and a au-sn layer 32, and the kovar layer 31 is located above the au-sn layer 32 and is connected to the quartz glass cover plate.

The specific embodiment of the utility model adopts kovar alloy as 4J29 mark, 0-300 ℃ expansion coefficient (4.7-5.5) x 10^-6K, coefficient of expansion of the quartz glass 0.55X 10^-6K, expansion coefficient of eutectic alloy of gold and tin is 16 x 10^-6and/K. The expansion coefficient of the kovar alloy is between that of quartz glass and gold tin, and the kovar alloy is used as metal for connecting the quartz glass and the gold, so that the problem of thermal stress can be avoided, and the reliability of the packaging structure is improved.

Example 3

An all inorganic packaging structure of a UV LED, as shown in figure 1, figure 2 and figure 3, comprises a quartz glass cover plate 1, a metal frame 2, a metal connecting layer 3, a UV LED flip chip 4, a bonding pad 5, a first electrode 6, a ceramic substrate 7, a thermoelectric separation structure 8 and a second electrode 9. The ceramic substrate is made of aluminum oxide material, two through holes are formed on the ceramic substrate 7 in a deep reactive ion etching mode, copper is filled in the through holes in a sputtering mode, copper layers with the thickness of 1000 microns are formed on the upper surface and the lower surface of the ceramic substrate respectively, photoresist covers the upper surface and the lower surface of the ceramic substrate in a yellow light lithography mode, gold layers with the thickness of 50 microns are exposed, developed, etched, stripped and electroplated, a bonding pad 5 is formed on the upper surface corresponding to each through hole, a second electrode 9 is formed on the corresponding lower surface, and the bonding pad 5 is electrically connected with the second electrode 9 through copper.

And fixing the first electrodes 6 below the four UV LED flip chips 4 on the upper surface of the bonding pad by using solder paste so that the four UV LED flip chips 4 are connected in parallel and electrically connected with the second electrodes 9. The metal frame 2 is made of copper, a gold layer and a copper layer are sequentially welded between the metal frame and the substrate in a hot-pressing mode, a groove is formed in the inner side of the metal frame 2, two ends of the quartz glass cover plate 1 are embedded into the groove so that the quartz glass cover plate 1 is suspended above the four UV LED chips 4, and the upper surface of the quartz glass cover plate 1 is flush with the upper surface of the metal frame 2. A gold layer with the thickness of 50 mu m and a kovar alloy layer with the thickness of 100 mu m are electroplated between the metal frame and the quartz glass cover plate in sequence.

The specific embodiment of the utility model adopts kovar alloy as 4J34 mark, 0-300 ℃ expansion coefficient (6.2-7.5) x 10^-6K, coefficient of expansion of the quartz glass 0.55X 10^-6K, coefficient of expansion of gold 14.2X 10^-6and/K. The expansion coefficient of the kovar alloy is between that of quartz glass and gold, and the kovar alloy is used as metal for connecting the quartz glass and the gold, so that the problem of thermal stress can be avoided, and the reliability of the packaging structure is improved.

In the above embodiment, the copper in the through hole of the ceramic substrate is electrically connected with the bonding pad and the second electrode, so as to perform a conductive function; the thermoelectric separation structure is used for enhancing the heat dissipation capacity of the chip and preventing the chip from losing efficacy due to high temperature; the gold layer or the gold-tin layer is arranged on the surfaces of the metal frame and the copper layer, so that the copper layer is prevented from being oxidized on one hand, and the bonding and fixing effects are achieved on the other hand; the quartz glass cover plate is arranged in the groove on the inner side of the metal frame, so that the quartz glass cover plate can be effectively protected and prevented from being damaged by collision; the quartz glass has the excellent characteristics of strong ultraviolet radiation resistance, difficult aging, small expansion coefficient, extremely low moisture and oxygen permeability and the like, so that the packaging structure is more stable and the air tightness is better. In addition, the area of the copper layer in the second electrode is larger than that of the gold layer, so that the UV LED all-inorganic packaging structure in the embodiment can be more tightly fixed on an application end device, and the reliability of the device is improved.

The above only be the utility model discloses a preferred embodiment, the utility model discloses a protection scope is not limited to here, and is any based on the utility model discloses equivalent transform on the technical scheme all belongs to within the protection scope.

Claims

1. The utility model provides a full inorganic packaging structure of UV LED, its characterized in that, includes base plate, chip, closing cap, the chip set up in on the base plate, the closing cap includes metal frame, apron, the metal frame inboard is provided with the recess, embedding all around of apron in so that the apron is unsettled in the top of chip, the metal frame set up in on the base plate, the apron upper surface with metal frame upper surface parallel and level.

2. The UV LED all-inorganic packaging structure of claim 1, wherein a first metal layer and a second metal layer are sequentially arranged between the cover plate and the metal frame.

3. The UV LED all-inorganic packaging structure of claim 2, wherein the first metal layer material is Kovar alloy, and the second metal layer material is gold or gold-tin alloy.

4. The UV LED all-inorganic packaging structure of claim 2 or 3, wherein the thickness of the first metal layer is 5 μm to 100 μm, and the thickness of the second metal layer is 5 μm to 50 μm.

5. The UV LED all-inorganic packaging structure of claim 1, wherein a through hole is formed on the substrate, a bonding pad is formed on the upper surface of the substrate corresponding to the through hole, a second electrode is formed on the lower surface of the substrate corresponding to the through hole, copper is filled in the through hole, so that the bonding pad is electrically connected with the second electrode through the copper, and the chip is disposed on the bonding pad through the first electrode, so that the chip is electrically connected with the second electrode.

6. The UV LED all-inorganic packaging structure of claim 5, wherein the second electrode comprises a copper layer and a gold layer from top to bottom, and the area of the copper layer is larger than that of the gold layer.

7. The UV LED all-inorganic packaging structure according to claim 1 or 5, wherein the number of the chips is single or multiple.

8. The UV LED all-inorganic packaging structure according to claim 1 or 5, wherein the chip is a flip LED chip, a vertical LED chip or a front-mounted LED chip.

9. The UV LED all-inorganic packaging structure of claim 1, wherein a gold layer and a copper layer are sequentially arranged between the metal frame and the substrate.

10. The UV LED all-inorganic packaging structure of claim 1, wherein the metal frame material is copper or aluminum, the substrate material is aluminum oxide or aluminum nitride, and the cover plate is a quartz glass cover plate.