CN203055985U - LED packaging structure - Google Patents

Abstract

The utility model relates to a LED packaging structure. The structure comprises a boss structure in an LED packaging substrate and a transparent thin plate with the same shape as the boss structure; conformal coating can be achieved in the package structure using a capillary self-aligned process. The specific fluorescent powder conformal coating process adopting the structure comprises the steps that fluorescent powder is coated on a boss structure of the LED packaging substrate, the transparent thin plate is self-aligned with the protruding structure after being contacted with fluorescent powder glue, and the uniform thickness distribution of the fluorescent powder around the LED chip required by the fluorescent powder conformal coating is realized. The conformal coating of the fluorescent powder can be compatible with the currently adopted fluorescent powder free dispensing coating process equipment, and simultaneously has the advantage of simple process; the simple design of the boss structure and the transparent thin plate structure can effectively meet the requirements of conformal coating of fluorescent powder on parameters such as thickness, geometric morphology and the like in different LED packaging structures.

Description

A kind of LED packaging structure

technical field

The utility model belongs to LED encapsulation technology, relates to an encapsulation structure of an LED fluorescent powder conformal coating method for realizing high light and color quality in the LED encapsulation, and will be especially applied in large-scale LED encapsulation production.

Background technique

LEDs (Light Emitting Diodes) are semiconductor light-emitting devices based on the principle of P-N junction electroluminescence. They have the advantages of high electro-optical conversion efficiency, long service life, environmental protection and energy saving, and small size. They are known as green lighting sources in the 21st century. If it can be applied to the field of traditional lighting, it will have a very significant energy-saving effect, which is of great significance in today's increasingly tense global energy sources. With the breakthrough of the third-generation semiconductor material technology represented by nitrides, the semiconductor lighting industry based on high-power and high-brightness light-emitting diodes (LEDs) is rapidly emerging in the world, and is becoming a new economic growth point for the semiconductor optoelectronics industry. There has been a revolution in lighting. Due to its unique advantages, LED has been widely used in many fields, such as landscape lighting, car headlights, street lights and backlights, etc. It is considered by the industry to be the main development direction of future lighting technology and has huge market potential.

The primary task of LED replacing traditional lighting methods is to improve its light output efficiency and reliability. Through years of research and technological development, the current light output efficiency of commercial LED products has reached 100 -130 lm/W, and the laboratory level has reached 231 lm/W, which is much higher than the light efficiency of traditional light sources; at the same time, with the improvement of packaging technology, optimization of heat dissipation structure and improvement of driving reliability, the reliability of LED has also been greatly improved. In order to further improve the lighting quality of LED products, more and more attention has been paid to the quality of LED light color, which can specifically include two aspects: LED light color consistency and LED space color uniformity. For example, the US Department of Energy will improve LED light color consistency, Reducing the number of bins is one of the five major challenges in the development of LED lighting. At the same time, the US Energy Star (Energy Star) has listed the spatial color uniformity of LED packages and lamps as one of the LED lighting quality evaluation indicators in 2008. With the rapid promotion of LED in the field of indoor lighting (such as commercial lighting, home lighting, office lighting, etc.), people's requirements for LED lighting have gradually changed from "lighting" to "comfortable lighting". Advanced packaging technology, improving LED light color consistency and spatial color uniformity, has become an important technical goal to expand the field of LED lighting and accelerate the replacement of traditional lighting by LED.

High-power white LEDs are usually mixed with two-wavelength light (blue light + yellow light) or three-wavelength light (blue light + green light + red light). Currently widely used white LEDs are composed of blue LED chips (GaN) and yellow phosphors (YAG or TAG). In the LED packaging, the parameters of the phosphor layer seriously affect the important optical properties of the LED, such as light extraction efficiency, color temperature, and spatial color uniformity. At present, the most commonly used phosphor coating method in LED packaging is phosphor free dispensing coating. This phosphor coating method has the advantages of simple process and low cost; however, this phosphor coating method It often leads to a large difference in the color temperature spatial distribution of the final LED package product, which seriously affects the lighting quality of the LED product. Researchers at home and abroad have carried out a lot of research work and found a method for conformal coating of LED phosphors, that is, coating a phosphor layer with a uniform thickness on the surface of the LED chip. The conformal coating method requires the ability to control parameters such as the geometric shape and thickness of the phosphor, thereby improving the light color consistency and spatial color uniformity of LED packaging products; however, the packaging implementation process is difficult. In order to realize the conformal coating of phosphor powder, the electrophoresis method (U. S. patent 6,576,488), the solution evaporation method (U. S. patent 7,217,583), and the wafer-level packaging (B. Braune et al. , Proc. SPIE 6486, 64860X, 2007) and the current pulse spraying process described in relevant literature (H. T. Huang et al. , OPTICS EXPRESS, 18, A201, 2010). Among them, the electrophoresis method and solution evaporation method are more complex and costly to achieve conformal coating; the process methods of wafer level packaging and pulse spraying have higher requirements on packaging equipment, the process must be precisely controlled, and the conformal coating of LED horizontal chips cannot be achieved. coated. Therefore, the development of a phosphor conformal coating that is simple in process, low in cost and applicable to all LED chip types is essential for packaging LED optical products with high optical quality.

Contents of the invention

The utility model provides an LED packaging structure, which can be used to realize the conformal coating of fluorescent powder. Adopting the structure can realize phosphor powder conformal coating according to microfluidic self-alignment effect.

The LED packaging structure proposed by the utility model is characterized in that it includes an LED packaging substrate and a transparent thin plate; the LED packaging substrate adds a boss structure at the place where the LED chip is fixed, and the side wall of the boss structure can be vertical or inclined to The horizontal plane of the LED package substrate, the height of the boss structure can be 0.01 to 3 mm, the size of the boss structure is 1 to 3 mm, and the boss structure is a round platform, a square platform or a polygonal platform; the material of the LED package substrate can be It is made of metal, plastic material, ceramic material or other materials currently used for LED packaging; the size of the transparent thin plate is 1 to 3 mm, and the thickness is 0.1 to 1 mm. The material of the transparent thin plate is transparent inorganic materials such as glass or transparent materials such as PMMA. Organic material, the shape is circular frustum, square frustum or polygonal frustum.

The LED packaging structure proposed by the utility model realizes conformal coating with high optical performance through a simple fluorescent powder coating process; the LED packaging process that realizes conformal coating by changing the LED packaging structure can be compared with the currently widely used phosphor powder Compatible with the free dispensing device, only adding a simple transparent thin plate and placement process, so it has the advantages of good operability and rapid and wide application, and can realize conformal coating through the shape design of the transparent thin plate and the convex structure of the LED packaging substrate The geometric shape of the coating phosphor layer is controlled, so this technology can be applied to non-encapsulating structures.

Description of drawings

Figures 1-4 are the application of the phosphor conformal coating technical solution of the present invention on the lead frame structure; wherein Figure 1 is a lead frame substrate containing protrusions for realizing capillary self-alignment, Figure 2 is a transparent thin plate, and Figure 3 In order to apply phosphor glue on the substrate bumps, Figure 4 (a)-(c) shows that the transparent sheet is in contact with the phosphor glue to achieve self-alignment, and finally achieve phosphor conformal coating;

Figures 5-8 show the application of the phosphor powder conformal coating technical solution of the present invention on a ceramic substrate; wherein Figure 5 shows a ceramic substrate containing protrusions for realizing capillary self-alignment, Figure 6 shows a transparent thin plate, and Figure 7 shows a Phosphor powder glue is dotted on the protrusions of the substrate. Figure 8 shows that the transparent thin plate is in contact with the phosphor powder glue to achieve self-alignment and finally conformal coating of phosphor powder.

The symbols in the figure are: (1001) lead frame LED packaging substrate, (1002) heat sink, (1003) molding compound, (1004) bracket pins, (1005) LED chip, (1006) glass sheet, (1007) Phosphor glue, (1008) phosphor layer, (1009) phosphor dispensing device, (1010) boss structure, (2001) ceramic LED packaging substrate, (2002) wire bonding point, (2003) ceramic layer, (2004) ) boss structure, (2005) PDMA sheets.

Detailed ways

The utility model proposes an LED packaging structure applied to LED packaging with conformal coating of fluorescent powder. The LED packaging structure includes an LED packaging substrate and a transparent thin plate.

The material of the LED packaging substrate can be metal substrate materials such as copper and aluminum, and non-metal substrate materials such as silicon, ceramics and PCB boards;

The transparent sheet material is glass, PDMA, PC and other transparent materials;

The structure of the LED package substrate can be realized by CNC milling machine, wire cutting, forging, injection molding and etching;

The surface of the LED packaging substrate is a reflective layer, and the material of the reflective layer can be silver or other reflective materials;

The transparent thin plate is realized by CNC milling machine, wire cutting, forging, injection molding and etching;

The material of the transparent sheet is a transparent inorganic material such as glass or a transparent organic material such as PMMA;

The conformal coating method of fluorescent powder glue coating is realized by the utility model: add phosphor powder into the glue material, mix evenly, adjust the ratio between the phosphor powder and glue material, and the proportioning concentration is 0.01g/ml~5.0g /ml of phosphor powder glue, after completing the process of fixing the LED chip and connecting the circuit, pass the phosphor powder glue through the dispensing coating device and apply it along the center of the convex structure area of the LED packaging substrate. Due to the stagnation of the edge of the convex structure effect, the phosphor glue stays on the top surface of the boss structure. Use the clamping tool to bring the transparent film close to the phosphor glue, and then whether the clamping tool is constrained, the phosphor glue will align the mobile transparent thin plate with the boss structure of the LED packaging substrate, and the phosphor glue is between the boss structure and the transparent thin plate. This enables phosphor conformal coating.

The LED chips used for packaging can be composed of binary materials such as GaN or quaternary materials such as AlGaNP and other chips.

The phosphor in the phosphor glue can be the phosphor used in all LED packages such as YAG and TAG.

The glue material used for configuring phosphor glue can be composed of glue materials such as silica gel, epoxy resin, and liquid glass.

The concentration of the phosphor powder in the phosphor powder glue can be 0.01g/ml~5.0g/ml.

The glue and phosphor glue can be transferred to the LED packaging substrate through syringe dripping, spraying and other ways.

The method can be applied to LED package forms such as bracket type, chip on board, array type and system package.

The utility model is described in more detail below by means of examples, but the following examples are only illustrative, and the protection scope of the utility model is not limited by these examples.

Example 1

Referring to FIG. 1 , it is a lead frame LED packaging substrate 1001 for LED packaging including a boss structure 1010 , and the boss structure 1010 is a rectangular structure. As shown in FIG. 3, after the LED chip 1005 is bonded to the center of the top surface of the boss structure 1010, and the gold wire 1004 wire bonding process is completed, the phosphor powder glue 1007 with a concentration of 0.5 g/ ^cm3 passes through the phosphor powder dispensing device 1009 is dot-coated on the top surface of the boss structure 1010 , the volume of the fluorescent powder glue is 0.4 μL, and it can cover the LED chip 1005 . As shown in Figure 4(a)-(c), the glass thin plate 1006 with the same shape as the boss structure 1010 contacts the phosphor powder glue 1007, the thickness of the glass thin plate is 0.2 mm, and the glass thin plate 1006 will Aligned with the mesa structure 1010 , phosphor glue 1007 is confined between the glass sheet and the mesa structure 1010 , forming a phosphor layer 1008 uniformly distributed around the LED chip 1005 . The LED module that has completed the above process is transferred to a baking oven at a temperature of 150° C. for 1 hour to cure the phosphor glue, so as to realize the conformal coating of the phosphor in the LED package.

Example 2

Referring to FIG. 5 , it is a ceramic LED packaging substrate 2001 for LED packaging including a boss structure 2004 , and the boss structure 2004 is a circular structure. As shown in FIG. 7, after the LED chip 1005 is bonded to the center of the top surface of the boss structure 2004, and the gold wire 1004 wire bonding process is completed, the phosphor powder glue 1007 with a concentration of 0.8g/ ^cm3 is sprayed by phosphor powder The device 1009 is spot-coated on the top surface of the boss structure 2004 with a volume of 0.28 μl and can cover the LED chip 1005 . As shown in Figure 8, the PDMA sheet 2005 with the same shape as the boss structure 2004 contacts the phosphor glue 1007, and then the PDMA sheet 2005 will be aligned with the boss structure 2004, and the phosphor glue 1007 is limited between the PDMA sheet and the boss structure 2004 Between them, a phosphor layer 1008 uniformly distributed around the LED chip 1005 is formed. The LED module that has completed the above process is transferred to a baking oven at a temperature of 150° C. for 1 hour to cure the phosphor glue, so as to realize the conformal coating of the phosphor in the LED package.

The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Therefore, all equivalents or modifications that do not deviate from the spirit disclosed in the present invention fall within the protection scope of the present invention.

Claims (5)

1. a LED encapsulating structure is characterized in that, comprises LED base plate for packaging and transparent thin board; Described LED base plate for packaging increases by a boss structure at fixed L ED chip place, the sidewall of described boss structure can be vertically or is favoured the horizontal plane of LED base plate for packaging, the height of boss structure is between 0.01 to 3 millimeter, and boss structure is of a size of between 1 to 3 millimeter; Transparent thin board is of a size of between 1 to 3 millimeter, and thickness is between 0.1 to 1 millimeter.

2. LED encapsulating structure according to claim 1 is characterized in that, described boss structure is round platform, square platform or polygon terrace with edge.

3. LED encapsulating structure according to claim 1 is characterized in that, the material of described LED base plate for packaging can be metal, plastic material, ceramic material.

4. LED encapsulating structure according to claim 1 is characterized in that, the material of described transparent thin board is glass transparent inorganic material or PMMA, PC transparent organic material.

5. LED encapsulating structure according to claim 1 is characterized in that, described transparent thin board is round platform, square platform or polygon terrace with edge.

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