CN201956388U - Softly connected LED (light-emitting diode) device based on liquid metal substrate - Google Patents

Abstract

The utility model discloses a flexible connection LED device based on a liquid metal base, which comprises an LED chip, a room temperature liquid metal layer, a packaging substrate, a structural adhesive layer, a fluorescent adhesive layer, electrodes and metal welding wires; the application of the utility model , the thermal resistance of the heat generated by the LED chip to the substrate will be greatly reduced, and the liquid metal will also generate convective heat transfer in the gap, which further enhances the heat dissipation effect; in addition, it can effectively avoid the welding and bonding between the two The stress and deformation problems brought about can avoid the thermal expansion of the substrate in a large temperature difference environment, which will cause a large stress on the chip, thus effectively solving the problem of further thinning and enlarging the chip; in addition, the mirror reflection formed by the liquid metal on the chip It can maximize the use of backscattered light, make the LED light source work at a lower temperature, obtain higher luminous efficiency, longer life, and higher reliability, and will realize the progress of high-power LED packaging technology .

Description

A kind of flexible connection LED device based on liquid metal substrate

technical field

The utility model relates to an illumination light source, in particular to an LED device based on a flexible connection of a liquid metal base.

Background technique

LED light source is a new generation of green lighting source. Its power consumption is only one tenth of that of ordinary incandescent lamps, but its life is more than ten times longer. In addition, LED light sources also have the advantages of small size, durability, and rich colors. In order to meet the requirements of higher light intensity, the LED light source is realized by increasing the output power of a single chip or using an LED array. Under ideal conditions, matching optical materials and appropriate packaging structures can give full play to the efficient light-emitting performance of LEDs and convert most of the electrical energy into light. However, due to the very small area of the LED chip, a large amount of heat cannot be dissipated in time, which causes the temperature of the LED to be too high during operation. Excessive temperature has a great impact on the output light intensity and color temperature performance of high-power LED light sources, especially the PN junction of the LED chip works at high temperature for a long time, and its optical performance will quickly decay, seriously affecting the service life of the LED. This is a key problem that needs to be solved in LED packaging. In addition, in a large temperature difference environment, the thermal expansion of the substrate causes a lot of stress in the chip under working conditions. This stress is not a big problem when the chip is small, but it is large. When the power LED chip (above 45mil) may even cause the chip to break, this is also a key factor restricting the further thinning and enlarging of the LED chip.

How to adopt a better cooling method on the premise of low cost to make the LED light source work at a lower temperature to obtain higher luminous efficiency, longer life, and higher reliability is a problem to be solved by this utility model. key issues.

The traditional LED packaging technology realizes the connection between the chip and the substrate through silver glue. This connection mainly has two functions of heat dissipation and fixing the chip. However, the silver glue process has the following problems: (1) The thermal conductivity is not high, and Due to the influence of the curing process, the heat dissipation of the chip is not good; (2) The stress of the chip is too large. After the silver glue is cured, the thermal expansion of the substrate causes a lot of stress in the chip under working conditions. This stress is not a big problem when the chip is small. However, high-power LED chips (above 45mil) may even cause chip breakage; (3) silver glue absorbs light, and most of the backscattered light from the chip is absorbed by the silver glue, thus causing this part of the light to be completely lost; (4) ) The silver glue process is complicated, and the curing of the silver glue needs to be baked at a high temperature of 150-170 degrees for nearly an hour, which will cause thermal damage to the LED chip and other components.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a flexible connection LED device based on a liquid metal substrate.

The purpose of this utility model is achieved through the following technical solutions: a flexible connection LED device based on a liquid metal substrate, which includes an LED chip, a room temperature liquid metal layer, a packaging substrate, a structural adhesive layer, a fluorescent adhesive layer, and an electrode , Metal welding wire. Wherein, the lower surface of the LED chip is immersed in room temperature liquid metal, and the room temperature liquid metal layer is used to realize the stress-free soft connection between the LED chip and the packaging substrate. The fixed connection between the substrates, the LED chip is covered with a fluorescent glue layer, the positive and negative electrodes are installed on the edge of the packaging substrate, and the LED chip and the electrodes are connected by metal welding wires.

The beneficial effects of the utility model are: applying the utility model, after the room temperature liquid metal is filled between the LED chip and the substrate, the thermal resistance of the heat generated by the LED chip to the substrate will be greatly reduced, and the liquid metal will also Convective heat transfer occurs in the gap, which further enhances the heat dissipation effect; in addition, it can effectively avoid the stress and deformation problems caused by welding and bonding between the two, and can avoid the thermal expansion of the substrate in a large temperature difference environment, which will cause a large stress on the chip. This effectively solves the problem of further thinning and enlarging the chip; in addition, the specular reflection formed by the liquid metal on the chip can maximize the use of backscattered light, so this process will make the LED light source work at a lower Working at high temperature, obtaining higher luminous efficiency, longer life, and higher reliability will realize the progress of high-power LED packaging technology.

Description of drawings

Fig. 1 is a structural schematic diagram of the LED device based on the flexible connection of the liquid metal substrate of the present invention;

In the figure: LED chip 1, room temperature liquid metal layer 2, packaging substrate 3, structural adhesive layer 4, fluorescent adhesive layer 5, electrode 6, metal bonding wire 7.

Detailed ways

Liquid metal is a metal that is liquid at normal temperature (such as below 100 degrees Celsius). This material has a large thermal conductivity, has fluidity at normal temperature, and can penetrate into very fine spaces. It can be used to reduce two The thermal contact resistance between different materials. This process can realize a stress-free connection between the chip and the substrate. Since the thermal conductivity of the gallium alloy is much higher than that of the silver glue (45-80W/m/K), the heat conduction effect is better. In addition, the specular reflection formed by the gallium alloy on the chip Backscattered light can be utilized to the maximum extent, so this process will realize the advancement of high-power LED packaging technology.

The utility model will be described in detail below in conjunction with the accompanying drawings, and the purpose and effect of the utility model will become more obvious.

As shown in Figure 1, an LED device based on a flexible connection of a liquid metal substrate includes an LED chip 1, a room temperature liquid metal layer 2, a packaging substrate 3, a structural adhesive layer 4, a fluorescent adhesive layer 5, electrodes 6, metal solder Line 7. Wherein, the lower surface of the LED chip 1 is immersed in liquid metal at room temperature, and the stress-free and flexible connection between the LED chip 1 and the package substrate 3 is realized through the room temperature liquid metal layer 2. The periphery of the LED chip 1 is covered with a structural adhesive layer 4, and the structural adhesive layer 4 Realize the fixed connection between the LED chip 1 and the package substrate 3 , the LED chip 1 is covered with a fluorescent adhesive layer 5 , the positive and negative electrodes 6 are installed on the edge of the package substrate 3 , and the LED chip 1 and the electrodes 6 are connected by metal bonding wires 7 .

The room temperature liquid metal layer 2 is a metal or alloy that is liquid below 100 degrees Celsius, such as gallium or gallium alloys. The packaging substrate 3 has a circular, square, triangular, regular hexagonal cross-section; the upper surface is a plane or concave-convex surface, and is designed with a surface structure for fixing the electrode 6; the lower surface is a plane or concave-convex surface, and is designed for Socket-type or screw-type structure for fixing the base plate 3. The structural adhesive layer 4 is a kind of soft adhesive, such as UV adhesive or silica gel, to realize the fixed connection between the LED chip 1 and the packaging substrate 3 . The LED chip 1 is covered with a fluorescent glue layer 5 , and the fluorescent glue layer 5 is a thin layer made of silica gel or epoxy resin material. Electrode 6 is a metal electrode or a circuit board. The metal bonding wire 7 is a good conductor metal wire such as a gold wire or a copper wire, and connects the LED chip 1 and the electrode 6 .

The utility model makes full use of the permeability and fluidity of the liquid metal, fills the gap between the contact surface of the LED chip 1 and the package substrate 3 with liquid metal, realizes the seamless flexible connection between the LED chip 1 and the package substrate 3, and utilizes the liquid metal The high thermal conductivity of metal improves the heat dissipation of LED chip 1 .

The working process of the utility model is as follows: the light generated by the LED chip 1 is emitted through the fluorescent adhesive layer 5 , and most of the heat generated by the LED chip 1 is conducted to the packaging substrate 3 . The traditional LED packaging technology uses silver glue to realize the functions of fixing the chip and heat dissipation, but the silver glue technology has problems such as low thermal conductivity, large chip stress, and high light loss. In order to solve these problems, the utility model is based on the LED chip 1 and A liquid metal layer 2 is added between the packaging substrates 3 . This liquid metal is a metal or alloy that is liquid below 100 degrees Celsius, such as gallium or an alloy of gallium. For example, metal gallium is a metal that can become liquid at 30 degrees Celsius. This liquid metal has a large thermal conductivity, good fluidity and wettability, and can completely penetrate between the LED chip 1 and the package substrate 3 in the gap. The heat generated by the LED chip 1 in the working state is conducted to the packaging substrate 3 through the liquid metal layer 2 . This liquid metal has a very large thermal conductivity, which is much higher than that of silver glue. The heat generated by the LED chip 1 conducts to the package substrate 3 and the thermal resistance drop is greatly reduced. In addition, the liquid metal will also generate resistance in the gap Heat transfer further enhances the cooling effect. The effect of this method is equivalent to completely fusing the LED chip 1 and the packaging substrate 3 together. This fusion is different from soldering or silver glue bonding between the LED chip 1 and the packaging substrate 3 , and can effectively prevent the chip from being damaged due to the thermal expansion of the substrate under a large temperature difference environment. In addition, the specular reflection formed on the upper surface of the liquid metal layer 2 can maximize the use of the backscattered light generated by the LED chip 1, effectively improving the overall light efficiency. In addition, a soft structural adhesive layer 4 is provided around the LED chip 1 and the liquid metal layer 2 to realize the fixed connection between the LED chip 1 and the packaging substrate 3 and to prevent the loss of liquid metal.

Claims (1)

1. the LED matrix based on the soft connection of liquid metal substrate is characterized in that, it comprises led chip (1), room temperature liquid metal layer (2), base plate for packaging (3), structure glue-line (4), fluorescence glue-line (5), electrode (6) and metal bonding wire (7); Wherein, described led chip (1) lower surface immerses in the room temperature liquid metal, realize unstressed soft the connection by room temperature liquid metal layer (2) between led chip (1) and the base plate for packaging (3), led chip (1) periphery is coated with structure glue-line (4), structure glue-line (4) is realized fixedlying connected between led chip (1) and the base plate for packaging (3), is coated with fluorescence glue-line (5) on the led chip (1); Positive and negative electrode (6) is installed at base plate for packaging (3) edge, is connected by metal bonding wire (7) between led chip (1) and the electrode (6).

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