CN105914285A - LED packaging substrate - Google Patents

Abstract

An LED packaging substrate, the LED packaging substrate includes: a packaging substrate for protecting and carrying LED chips; a reflective layer located on the packaging substrate; a light conversion layer located on the reflective layer; The LED chip without packaging substrate on the layer can emit light of specific wavelength bidirectionally. The packaging substrate disclosed by the present invention is characterized in that it includes a light conversion layer, which simplifies the packaging process. At the same time, its preparation process is conducive to mass production of packaging substrates containing uniform phosphors, improving product yield and productivity.

Description

A kind of LED packaging substrate

technical field

The invention relates to a packaging substrate based on a light-emitting diode and its preparation method, in particular to a packaging substrate containing light conversion materials.

Background technique

Solid-state lighting, especially light-emitting diodes (LEDs), is increasingly replacing fluorescent lamps/incandescent lamps as a new generation of light sources due to its long life, no pollution, and high luminous efficiency. Since the LEDs prepared by direct production are all monochromatic light, to obtain white light, a variety of colors must be mixed to form. The most common way to prepare white light LEDs is to use blue/ultraviolet light LEDs to excite light conversion materials, and the light emitted by the LED itself and the complementary light converted by the light conversion layer together form white light.

The manufacturing process of the existing LED packaging body is as follows: provide an LED packaging substrate, bond the LED chip on the packaging substrate, apply phosphor powder on the chip after bonding, and then bake and shape it. After the blue light emitted from the LED chip passes through the phosphor layer, part of it is absorbed by the phosphor and converted into yellow light, which is mixed with blue light to form white light.

The most critical step in the packaging process is coating phosphor, and the existing technologies—whether dispensing glue or spraying powder—have their insurmountable shortcomings. The dispensing method is to use a dispensing machine to respectively dispense prepared fluorescent glue on the packaging substrate on which the LED chip is pre-fixed. Due to the fluctuation of the dispenser machine (pressure, voltage, etc.), the glue dispensed on each LED chip is not the same. At the same time, due to the sedimentation of phosphor powder, the concentration of phosphor powder contained in each LED chip is also different. These two points eventually lead to differences in the color points of white LED chips manufactured in the same batch, resulting in defects. In addition, the dispensing speed of the dispensing machine is slow, and the production capacity is limited in mass production. Although the method of powder spraying and coating phosphor has improved the uniformity of color points, due to the large area of powder spraying each time, the edge of the sample to be sprayed will cause a lot of waste. At the same time, the powder spraying equipment is expensive, and the cost of each package becomes higher.

Contents of the invention

The purpose of the present invention is to simplify the LED packaging process and improve the shortcomings of the existing phosphor powder coating method, mainly by preparing the phosphor powder on the substrate when preparing the packaging substrate, so that the packaging only needs to complete the die-bonding and wire-bonding processes.

To achieve this purpose, the present invention provides a base, which is used to carry the rest of the packaging substrate; a reflective layer deposited on the base is used to reflect the light emitted by the LED chip and emitted after being absorbed by the phosphor and a light conversion layer prepared on the reflective layer, which is used to absorb the blue light emitted by the LED chip towards the packaging substrate and convert it into yellow light. In this way, the blue light emitted by the chip facing upwards and the yellow light reflected by the reflective layer are mixed together to form white light.

In one embodiment, the base is a ceramic base, on which a circuit is pre-arranged for conduction with the LED chip during subsequent use; and then a reflective material is plated on the surface of the ceramic base as a reflective layer . Wherein, a conductive material, such as silver, is plated on the base circuit. Plating insulating materials on the remaining parts, such as DBR, etc.; finally, the ceramic phosphor sheet is aligned and attached to the ceramic base, and sintered at 500°C-1000°C; wherein, the ceramic phosphor sheet is pre-drilled. hole, and fill the through hole with conductive material.

In one embodiment, a ceramic phosphor sheet is provided first, a through hole is drilled on it, and a conductive material is filled in the through hole; an insulating material is used to make a partition bar on the back of the ceramic phosphor sheet to separate the front and rear sides. Negative electrode through hole; plate a conductive reflective material on the back of the ceramic phosphor sheet as a reflective layer, such as silver; plate a thick (more than 100 micron) conductive layer under the reflective layer on the back of the ceramic phosphor sheet , used to protect and support the phosphor sheet and reflective layer, and play the role of a base. The manufacturing method is characterized in that the conductive light-reflecting layer and the thick conductive layer are separated by the partition bar at the positive and negative electrode through holes.

In one embodiment, a base is provided on which grooves, circuits and soldering bumps are pre-arranged. The groove is used to place the fluorescent powder layer; the circuit and welding bumps are used to form an electrical connection with the LED chip; the surface of the base is plated with a reflective material as a reflective layer. Conductive material, such as silver, is plated on the base circuit. Plating insulating materials on the remaining parts, such as DBR, etc.; coating the prepared fluorescent glue on the surface of the base, baking at 100°C-500°C; grinding/cutting to flatten the surface of the fluorescent glue to expose solder bumps.

Although the present invention will be described below in conjunction with some exemplary implementations and usage methods, those skilled in the art should understand that the present invention is not intended to be limited to these embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In addition, the drawing data are descriptive summaries and are not drawn to scale.

Figure 1 is a schematic cross-sectional view of Example 1.

Fig. 2 is the preparation flowchart of embodiment 1.

3 is a schematic cross-sectional view of Embodiment 2.

Fig. 4 is the preparation flowchart of embodiment 2.

5 is a schematic cross-sectional view of Embodiment 3.

Fig. 6 is the preparation flowchart of embodiment 3.

Each label in the figure means:

101 ceramic base

102 ceramic body

103 Circuit under ceramic base

104 Circuit on ceramic base

105 through-hole conductive column inside the ceramic base

106 insulating block

107, 207 Ag reflective layer

108, 208 DBR reflection layer

109, 209 ceramic phosphor powder

110, 210 Through-hole conductive column inside the ceramic phosphor sheet

212 conductive base

301 base

302 insulated base body

303 circuit

304 solder bumps

305 white reflective paint

306 fluorescent glue

307 Groove

detailed description

The implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and examples, so as to fully understand and implement the process of how to apply technical means to solve technical problems and achieve technical effects in the present invention. It should be noted that, as long as there is no conflict, each embodiment and each feature in each embodiment of the present invention can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

Example 1:

A schematic cross-sectional view of a single packaging substrate prepared and cut in Example 1 is shown in FIG. 1 . The preparation process is shown in FIG. 2 . Firstly, a pre-prepared ceramic base 101 is provided. The ceramic base includes a ceramic body 102, a lower surface circuit 103, an upper surface circuit 104, a through-hole conductive post 105 inside the ceramic base connected to the upper and lower surface circuits, wherein the circuits on the same surface are separated by an insulating block 106; the ceramic base The seat material can be aluminum oxide, aluminum nitride, etc., preferably, aluminum oxide is used as the base. The material of the upper and lower surfaces and the through-hole conductive column can be one or an alloy of copper, silver and gold, preferably, copper is used as the conductive material. The insulating block 106 is made of aluminum oxide.

Then, a reflective layer is plated on the upper surface of the ceramic base, and a conductive reflective material is plated on the upper surface circuit 104, preferably, silver-plated 107; an insulating material is plated on the insulating block 106, preferably, DBR is plated. . Its implementation mode S11 can be: 1) DBR is plated on the whole surface first; 2) Use photoresist to draw a pattern on the DBR, and the upper part of the insulating block is blocked by photoresist, and the circuit position is exposed; 3) Etching the exposed DBR layer ; 4) depositing an Ag layer. 5) Remove the photoresist. The material of the DBR is a combination of silicon oxide and titanium oxide.

Finally, as shown in S12 , a pre-prepared ceramic phosphor sheet 109 is provided, which contains through-hole conductive pillars 110 . The ceramic phosphor sheet 109 is aligned and attached to the ceramic base 101, and sintered at 500°C-1000°C, preferably at 850°C.

The packaging substrate of the present invention is integrally formed by the base and the ceramic phosphor sheet, and the various parts are well combined, the structural strength is higher, and the electrical and thermal conductivity are better. At the same time, the fluorescent powder coating method of the present invention does not need to be coated on different packaging supports separately, which reduces the problem of large color point differences in the traditional dispensing method, and is more suitable for mass production. Finally, the back-emitting blue light from the LED travels inside the phosphor sheet twice as thick as it is. Therefore, more yellow light can be converted with thinner phosphors.

Example 2:

A schematic cross-sectional view of a single packaging substrate prepared and cut in Example 2 is shown in FIG. 3 . The preparation process is shown in FIG. 4 , providing a pre-prepared ceramic phosphor sheet 209 with conductive pillars 210 through holes inside.

Then, as shown in S21 , on the back of the ceramic phosphor sheet 209 , an insulating material is used to make a partition bar 208 to separate the positive and negative electrode through holes. Preferably, we here choose an insulating DBR, such as a combination of silicon oxide and titanium oxide. The implementation method is as follows: 1) DBR is plated on the entire surface first; 2) Patterns are drawn on the DBR with photoresist, and the area that needs to be insulated is blocked with photoresist, and the position that needs to be conductive is exposed; 3) The exposed DBR is etched. layer;

Then, as shown in S22, under the condition of retaining the photoresist in step S21, an Ag layer is further deposited on the back of the ceramic phosphor sheet as a reflective layer.

Finally, as shown in S23, under the condition of retaining the photoresist in step S21, a thick (more than 100 micron) conductive layer is further deposited on the back of the ceramic phosphor sheet to protect the supporting phosphor sheet and the reflective layer , which acts as a base. The material of the conductive layer is copper silver gold or its alloy. Preferably, the total thickness of the conductive layer and the Ag reflective layer is greater than the thickness of the DBR layer.

This embodiment is a simplified version of Embodiment 1, which is more advantageous in terms of cost because the ceramic base is saved.

Example 3:

A schematic cross-sectional view of a single packaging substrate prepared and cut in Example 3 is shown in FIG. 5 . The manufacturing process is shown in FIG. 6 , providing a base 301 on which grooves 307 , circuits 303 and welding bumps 304 are pre-arranged. Preferably, the base is made of engineering plastics, such as PPA, EMC, etc.; the circuit and solder bumps are made of copper.

Then, as shown in S31 , a reflective paint is selectively coated on the surface of the base 301 as a reflective layer. The reflective paint is coated on the surface of the base except the welding bumps.

Then, as shown in S32 , the prepared fluorescent glue 306 is coated on the surface of the base 301 and baked in an oven at 150° C. for four hours to shape.

Finally, grind/cut to planarize the fluorescent glue surface, exposing the solder bumps.

Claims (6)

1. a LED package substrate, including:

Pedestal, it is for carrying the remainder of base plate for packaging；

It is positioned at the reflecting layer on described pedestal；

It is positioned at the light conversion layer on described reflecting layer.

Base plate for packaging the most according to claim 1, it is characterised in that: described pedestal by plastics, metal, pottery one or Multiple combination forms.

Base plate for packaging the most according to claim 1, it is characterised in that: described pedestal also comprise heat conduction and conductive channel for Connection LED chip and external environment condition.

Base plate for packaging the most according to claim 1, it is characterised in that: described reflecting layer is by metallic mirror surface, photonic crystal, anti- One or more penetrating coating combine.

Base plate for packaging the most according to claim 1, it is characterised in that: the light-converting material of described light conversion layer is by fluorescence Powder, quantum dot, organic fluorescence/phosphor material one or more combine.

Base plate for packaging the most according to claim 1, it is characterised in that: the thickness of described light conversion layer is less than 1 millimeter.