TWI443880B - Led pasting method - Google Patents

Description

Method for grain adhesion of light-emitting diode

The invention relates to a method for bonding a crystal of a light-emitting diode, in particular to a method for crystallizing a light-emitting diode which has a simple process and has low heat resistance and can provide a better heat dissipation effect.

The existing light-emitting diode element is manufactured by first providing a light-emitting diode [LED] die, and then fixing the light-emitting diode die on the surface of a substrate to apply silver paste, which is adhered by silver glue. Fixing the light-emitting diode die, and then bonding the fixed light-emitting diode die together with the germanium substrate to a heat carrier coated with silver glue, and then connecting by wire bonding or soldering connection The light-emitting diode die and the electrode end communicate with each other, and then are configured by a transparent plastic casing to make it become a light-emitting diode component; and the heat-carrying seat of the light-emitting diode component is fixed to the coated heat conduction. Another circuit board of the paste (such as a PCB circuit board or a ceramic circuit board), the electrode end of the light emitting diode element is connected to the circuit end of the circuit board by a soft soldering method; and the light emitting diode element is included The circuit board is completed by thermally conductive paste mounted on the heat dissipation fins.

However, in the above-mentioned conventional method for bonding a crystal of a light-emitting diode, the heat conduction effect is limited, and the heat dissipation effect must be effectively improved between the light-emitting diode die and the substrate, so that the surface of each layer is additionally coated. Silver adhesive, thermal paste and other adhesives with heat-dissipating effect, so that the layer stack structure is easy to have high thermal resistance and reduce the overall heat transfer efficiency, and even increase the cumbersome and improved process of the LED die adhered to the substrate. The burden of cost.

Furthermore, the adhesion of the conventional silver paste or the thermal paste is easily caused by the heat and ultraviolet rays emitted from the LED die for a long time, and the silver paste or the thermal paste is aging and falling off. Thus, the conventional packaging method of the LED die not only seriously affects the heat conduction effect of the LED die, but also causes poor heat dissipation, and may even further damage the LED and reduce the service life of the LED.

For example, the Republic of China Publication No. 200729536 "A wafer adhesive material for a light-emitting diode package" comprises a light-emitting diode wafer electrically coupled to a carrier by a tin alloy as an adhesive material. In this way, the Cohesive Force can be internally contracted by the tin alloy, so that the wafer can be adhered to the tin alloy, thereby avoiding the shrinkage of the grain exit area caused by the solid crystal form of the conventional silver paste or even touching by the silver paste. The PN is connected to the interface layer to cause leakage, lack of brightness, etc., further increasing the brightness of the LED chip and the reliability of the die adhesion.

However, in the above patent, when a tin alloy is used as a material for bonding the light-emitting diode die and the substrate, the light-emitting diode is a hard-to-wet material and is not easily wet-bonded, and the tin alloy does not have an active component. It can only join joints with high wettability metal materials. It is difficult for wet metal materials (such as aluminum alloys, magnesium alloys, titanium alloys) or non-wetting ceramics, wafers, graphite or carbon fiber materials. Wet joint,. The surface of the light-emitting diode die must be subjected to a metallization process to have a metal layer on the surface of the LED wafer, so that the bonding can be successful with the conventional tin alloy, and thus the metallized layer is relatively thin, and it is easy to be lost during the re-bonding process. Therefore, the bonding strength between the light emitting diode and the substrate is remarkably insufficient.

Furthermore, the tin alloy as an adhesive material is easily limited by the inactive nature of the tin alloy itself, and only a metal substrate having high wettability can be selected for the light-emitting diode die bonding. Therefore, when the tin alloy is applied to a substrate having poor wettability, such as a non-metallic substrate such as glass or ceramic, or the surface is subjected to anodization or micro-arcing to form an aluminum substrate having a ceramic layer, the tin alloy cannot be made. In the case where the bonding is successful, the welding effect is not good; in order to improve the poor soldering, it is necessary to coat a metal layer on the substrate having no wettability and then bond it, but when the light emitting diode is When the substrates are joined together, the coated metal layer on the substrate having no wettability may be worn out, or the thermal stress may cause peeling, resulting in a poor soldering effect. Second, when the metal layer is repeatedly stacked, the interface thermal resistance coefficient is increased and the heat conduction efficiency is lowered. As a result, the tin alloy system cannot directly adhere the light-emitting diode crystal grains to the substrates of different materials, resulting in a poor use margin.

In view of the above disadvantages, the packaging method of the light-emitting diode die of the present invention is still necessary to be improved.

The main object of the present invention is to improve the above disadvantages, and to provide a method for crystallizing a light-emitting diode, which can heat the active solder to above the melting point of the active solder, causing the active solder to be in a molten state and destroyed by disturbance. An active oxide layer of the solder promotes diffusion of the active component to the bonding surface layer to cause a bonding reaction between the active element and the bonding material to enhance the bonding strength between the light emitting diode die and the substrate.

A second object of the present invention is to provide a method for bonding a light-emitting diode to a substrate of a different material to enhance the use margin of the light-emitting diode.

A further object of the present invention is to provide a method for crystallizing a light-emitting diode, which is capable of reducing an interface thermal impedance coefficient between the light-emitting diode and the substrate, thereby improving heat transfer efficiency.

In order to achieve the foregoing object, the method for crystallizing a light-emitting diode of the present invention comprises: a pre-processing step of heating an active solder to a temperature above the melting point of the active solder such that the active solder exhibits a molten state, wherein the active The solder is composed of at least one active element added by a solder; the first is to apply the molten solder in a molten state to a substrate in a disturbing manner, so that the substrate forms a circuit line and a solder joint with a molten active solder. a crystal point; in addition, the light-emitting diode crystal grains are simultaneously formed by the above method, and the solder joints and the solid crystal dots of the light-emitting diode crystal grains are formed; and then a light-emitting diode crystal grain is placed thereon. The substrate solder joint and the solid crystal point are cured by cooling and adhered to the surface of the substrate.

The method for bonding a light-emitting diode of the present invention may further preheat and perturb the substrate in the pre-processing step to activate the surface of the substrate; and in the pre-processing step, preferably The sonic-assisted perturbation method combines the active component of the active solder with the non-wetting substrate and the wafer, and at the same time disturbs the oxide film for protecting the surface layer of the active solder, so that the surface of the molten active solder presents a clean, fresh surface layer. And promote the diffusion of active ingredients to the surface.

The die attaching method of the light emitting diode of the present invention can be preceded by the circuit wire, the solder joint and the solid crystal point formed by the active solder melted at the two ends of the substrate, and the electroplating or electroless plating method is used for the active solder. Adding a conductive metal to the layer, or adding a metal barrier layer to the surface of the conductive metal to fix the soldering legs of the light-emitting diode die to the surface of the barrier layer; The auxiliary bonding step is performed by applying the active solder activated by the pre-processing step to the light-emitting diode die and the substrate to form a heat dissipation layer. The molten solder joints formed by the layers and the ends of the substrate are not in contact with each other.

In an embodiment of the invention, the active solder is selected from the group consisting of a tin-based alloy, a bismuth-based alloy, an indium-based alloy or other solder alloy, and 0.01 to 2% by weight of a rare earth element (Re) is added, and the rare earth element system thereof Refers to: 钪 element (Sc), 钇 element (Y) and "lanthanide element", of which "lanthanum element" includes: 镧 (La), 铈 (Ce), 鐠 (Pr), 钕 (Nd), giant (Pm), 钐 (Sm), 铕 (Eu) 釓 (Gd) 鋱 (Td), 镝 Dy, 鈥 (Ho), 铒 (Er), 銩 (Tm), 镱 (Yb) or 鑥 (Lu), However, in the utilization of the industry, the rare earth elements usually exist in the form of a mixture. The common rare earth element mixture usually consists of: La, Ce, Pr, Nd, Nd ( Sm) and a very small amount of iron, phosphorus, sulfur or antimony.

In an embodiment of the present invention, the tin-based alloy, the bismuth-based alloy or the indium-based alloy is blended with at least one active ingredient of at least 6% by weight, which is selected from the group consisting of titanium (Ti) and vanadium (including 4% by weight or less). V), magnesium (Mg), lithium (Li), zirconium (Zr), hafnium (Hf) or a combination thereof; and the remaining weight is a rare earth element selected from the group consisting of rare earth elements thereof: (Sc), yttrium element (Y) and "lanthanide element" or a combination thereof.

The active solder is preferably a tin-based alloy or an indium-based alloy mixed with an active element and a trace rare earth element; in particular, tin-3.5 silver-0.5 copper-4 titanium (0.2% mixed rare earth), tin-0.7 silver-0.7 Copper-4 titanium (0.2% mixed rare earth), indium-48 tin-4 titanium (0.2% mixed rare earth), indium-4 titanium (0.2% mixed rare earth) or tin-58 铋-4 titanium (0.2% mixed rare earth).

The above and other objects, features and advantages of the present invention will become more <RTIgt; The die attaching method of the light emitting diode according to the first embodiment of the present invention includes a pre-processing step S1 and a bonding step S2.

The pre-treatment step S1 is heated to bring the active solder into a molten state, and the oxide film of the active solder skin layer is removed in a disturbing manner, so that the active solder exhibits a fresh activated state, wherein the active solder is added with at least one active element by a solder. composition. More specifically, the solder is selected from a tin-based alloy, a bismuth-based alloy, an indium-based alloy or other solder alloy, and 0.01 to 2% by weight of a rare earth element (Re) is added, and the rare earth element is generally referred to as: Element (Sc), elemental (Y) and "lanthanide", of which "lanthanum" includes: 镧 (La), 铈 (Ce), 鐠 (Pr), 钕 (Nd), giant (Pm),钐 (Sm), 铕 (Eu) 釓 (Gd) 鋱 (Td), 镝 Dy, 鈥 (Ho), 铒 (Er), 銩 (Tm), 镱 (Yb) or 鑥 (Lu), but in the industry In terms of use, the rare earth elements usually exist in the form of a mixture, and the common rare earth element mixture is usually composed of: lanthanum (La), cerium (Ce), praseodymium (Pr), cerium (Nd), cerium (Sm), and A small amount of iron, phosphorus, sulfur or antimony.

In an embodiment of the present invention, the tin-based alloy, the bismuth-based alloy or the indium-based alloy is blended with at least one active ingredient of at least 6% by weight, which is selected from the group consisting of titanium (Ti) and vanadium (including 4% by weight or less). V), magnesium (Mg), lithium (Li), zirconium (Zr), hafnium (Hf) or a combination thereof; and the remaining weight is a rare earth element selected from the group consisting of rare earth elements thereof: (Sc), 钇 element (Y) And "lanthanides" or a combination thereof.

The bonding substrate can be selected as a metal substrate (such as aluminum, copper, etc.) or a non-metal substrate (such as ceramic, glass, aluminum nitride, zirconia, etc.); even, the substrate can be directly selected as a heat sink. In the subsequent adhesion step S2, after the active solder is applied to the heat sink, it is directly bonded to a light-emitting diode die 2.

Therefore, in the pre-treatment step S1, an extremely thin oxide film generated on the surface of the active solder must be destroyed before the active solder can maintain a better fresh activation state, and the active element of the active solder is diffused to the molten activity. The surface layer of the solder. For example, in the embodiment, the ultrasonic vibration can be used to accelerate the disturbance of the active solder to break the oxide film of the active solder surface layer, and promote the diffusion of the active elements and rare earth elements in the molten active solder to the surface layer. Active solder in the activated state; even, the bonded substrate 1 can be oscillated at the same time, thereby improving the bonding efficiency and the bonding strength in the subsequent bonding step S2.

The bonding step S2 is performed by heating the substrate 1 to 25 ° C above the melting temperature of the active solder, and using the molten active solder 3 to make the substrate 1 have a metal circuit line of active solder and two contact ends or more. The two ends of the light-emitting diode die 2 are respectively placed on the molten solder joints 3 at the two contact ends of the substrate 1, so that the light-emitting diode crystal grains 2 are cooled and solidified by the molten solder joints 3, and then bonded. On the surface of the substrate 1. More specifically, in the present invention, the pre-treatment step S1 and the bonding step S2 are heated to 5 ° C to 75 ° C above the melting point, so that the active solder is uniformly formed into a molten state, and the active solder can be formed at both ends of the substrate 1 . Melt solder joint 3. In this way, the two ends of the LED die 2 can be placed on the two ends of the substrate 1 respectively. On the molten solder joint 3, the light-emitting diode die 2 is closely adhered to the surface of the substrate 1, and then the light-emitting diode die 2 is cooled at the molten solder joint 3 to below the melting point of the active solder. After curing at 5 ° C to 25 ° C, it can be bonded to the surface of the substrate 1 . Preferably, the present invention selects ultrasonic bonding-assisted soldering between the substrate 1 and the light-emitting diode die 2, and during the ultrasonic vibration process, the molten active solder is directly applied and bonded to the substrate 1. Or actively bonding the light-emitting diode die 2 to the substrate 1, and the substrate 1 and the light-emitting diode die 2 are tightly bonded after the active solder is solidified, and the melting point of the substrate 1 is higher than The melting point of the active solder is used to avoid additional damage to the substrate 1 by the heating process.

For example, in the present embodiment, the active solder having a high melting point is coated on the two-end contact of the oxidized ceramic substrate 1 having high thermal conductivity, so that the active solder is melted at a temperature of 5 ° C to 75 ° C above the melting point. state. At this time, the two ends of the light-emitting diode die 2 are placed on the molten solder joint 3 of the two-end contact of the substrate 1, so that the active element and the rare earth element in the active solder can be activated. A new reaction layer is formed on the surface of the oxidized ceramic substrate 1, and after the light-emitting diode crystal grains are completely joined, and then cooled to a melting point of the molten solder joint 3 of 5 ° C to 75 ° C, the molten solder joint is made 3 curing to firmly bond the light-emitting diode crystal grains 2 to the surface of the oxidized ceramic substrate 1. In this way, the active solder can not only form a new bonding reaction layer between the LED body 2 and the oxidized ceramic substrate 1 to improve the bonding strength and efficiency between the two; the active solder bonding oxidized ceramic substrate 1 and illuminating After the diode die 2, the thermal impedance coefficient of the junction interface between the light-emitting diode die 2 and the oxidized ceramic substrate 1 can be effectively reduced, thereby improving the heat transfer efficiency and increasing the heat dissipation effect.

When the adhesion of the light-emitting diode die 2 is completed by the above method, the surface of the light-emitting diode die 2 may be selected to be connected to the two electrodes by wire bonding; or alternatively, the flip chip may be selected. The second electrode is formed on the end face of the contact point of the light-emitting diode die 2 and the substrate 1 , and the two electrodes are in contact with the active solder to turn on the two electrodes, thereby the light-emitting diode die 2 can be The two electrodes are electrically connected to the external power source to form a path to emit light.

As described above, the present invention is capable of bonding the light-emitting diode crystal 2 to the surface of the substrate 1 in a uniform molten state, so that the active element in the active solder can be bonded to the substrate 1 and the light-emitting diode. 2 forming a new bonding reaction layer, thereby enhancing the bonding strength of the light emitting diode die 2 on the surface of the substrate 1; even through the technique of ultrasonically assisting bonding the active solder to the surface of the substrate 1 by the present invention, The active element in the active solder can rapidly diffuse to the joint and bond the reaction layer to the surface of the substrate 1, thereby improving the efficiency of bonding the light-emitting diode crystal 2 to the surface of the substrate 1. Furthermore, the present invention can directly bond the light-emitting diode crystal 2 to the substrate 1 having a high thermal conductivity material by using the active solder, so that the light-emitting diode bonded by the method of the present invention is not only not suitable. The structure of the layer stack can be configured to have a lower thermal resistance, and the active solder is a highly thermally conductive metal material, thereby reducing the thermal impedance coefficient between the joint interfaces of the two, and can quickly generate the light-emitting diode crystal 2 The heat is transmitted to the outside of the substrate 1, thereby increasing the heat conduction efficiency to achieve a better heat dissipation effect; more avoiding the high temperature phenomenon of the LED 2 for a long time of use, thereby prolonging the service life of the LED The effect.

Furthermore, please refer to FIG. 3, the present invention is also applicable to the substrate 1 A conductive metal 4 is adhered to the molten solder joint 3 formed by the two-end molten active solder to increase the conductive and thermal conductive effect of the active solder connecting the light-emitting diode die 2. The conductive metal 4 is preferably selected as Copper, nickel, tin or a compound thereof; and a barrier layer 5 is formed on the surface of the conductive metal 4 by various methods (such as sputtering, coating, etc.) to prevent the light-emitting diode 2 from being adhered An excess of the intermetallic compound is generated with the conductive metal 4 to lower the bonding strength. Thus, in the present invention, the active solder can be arbitrarily combined with various articles according to different requirements under the application of the above method, so that the present invention can produce an improvement in effects such as bonding strength, electrical conductivity, thermal conductivity and the like.

In addition, referring to the fourth embodiment, the second embodiment of the present invention is the same as the first embodiment. The first step S1 and the bonding step S2 are the same as the first embodiment. The die attaching method of the polar body may further operate an auxiliary bonding step S2' while operating the bonding step S2, and the auxiliary bonding step S2' selects to apply the active solder activated by the pre-processing step S1 in the above manner. A heat dissipation layer 6 is formed between the light-emitting diode die 2 and the substrate 1, and more preferably, the heat dissipation layer 4 is prevented from coming into contact with the molten solder joint 3 formed at both ends of the substrate 1 to prevent the melting. The solder joint 3 causes a short circuit when the electrode is turned on, and in the bonding step S2, the active solder is also formed into a molten state by active soft soldering to form a high-strength bond with the light-emitting diode die 2 and the substrate 1. The reaction layer, whereby the heat dissipation layer 6 formed by the active solder provides a better heat transfer effect. The heat dissipation layer 6 is preferably selected from the same composition as the active solder. The heat dissipation layer 6 may be selected from the group consisting of a tin-based alloy, a bismuth-based alloy, an indium-based alloy, a solder alloy, an active element, and a rare earth. A group of elements.

For example, in the present embodiment, the high-melting-point active solder is coated on both ends of the oxidized ceramic substrate having high thermal conductivity, and the low melting point activity is applied between the light-emitting diode 2 and the oxidized ceramic substrate 1. Solder to form the heat dissipation layer 6 so that the heating temperature is higher than the melting point of the low melting point active solder 5 to 25 ° C, and the active solder which is located on the inner side as the heat dissipation layer 6 first turns into a molten state, and continues to heat up to a high melting point of the active solder. When the melting point is 5 to 50 ° C, the active solder of the two-terminal contact of the substrate 1 is then turned into a molten state, and the surface of the light-emitting diode 2 is attached to the heat dissipation layer 6 and the light-emitting diode crystal grains. 2nd end soldering foot is attached to molten solder joint 3 and then cooled to a melting point of high melting point active solder 5~25 ° C, so that the molten solder joint 3 is first solidified to firmly join the two end welding of the light emitting diode die 2 The foot is further cooled down until the heat dissipation layer 6 is cured to complete adhesion of the light emitting diode die 2 to the oxidized ceramic substrate 1. Thereby, the two-end soldering legs of the light-emitting diode die 2 can be firmly bonded to the oxidized ceramic substrate 1 by using the high-melting-point molten solder joint 3 to be cured first to prevent the light-emitting diode crystal. The possibility of deformation of the granule 2 during the bonding process. Wherein, the heat-dissipating layer 6 and the active solder selected for the molten solder joint 3 may have the same melting point, thereby also achieving the effect of preventing deformation of the light-emitting diode crystal 2 during the bonding process as described above.

In addition, referring to the sixth embodiment, the second embodiment of the present invention is the same as the first embodiment. The first step S1 and the bonding step S2 are the same as the first embodiment. The die attaching method of the polar body may further operate a film forming step S20 before the bonding step S2, the film forming step S20 is to immerse the substrate 1 in a modified material. An electric voltage is applied to the electrolyte to form an oxide film 7 on the surface of the substrate 1. More specifically, in this embodiment, the surface of the aluminum substrate 1 can be formed into an oxide film 7 by anodization, hard anodization or micro-arc oxidation treatment, and the oxide film 7 is a non-conductive film. The insulating layer can be directly formed on the surface of the aluminum substrate 1 to directly form a circuit pattern of active solder to form an insulating film. The modified material is selected from the group consisting of aluminum oxide, aluminum nitride, etc., so that the heat diffusion efficiency of the light-emitting diode crystal 2 of the present invention can be improved, so that the present invention has a better heat dissipation effect.

The die attaching method of the light emitting diode of the present invention is capable of bonding the light emitting diode to a substrate of different materials, thereby achieving the effect of improving the use margin of the light emitting diode.

The die attaching method of the light emitting diode of the invention can reduce the structural design of the layer stack to reduce the thermal resistance and improve the heat conduction efficiency, thereby achieving the effect of increasing the die life of the light emitting diode.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

〔this invention〕

1‧‧‧Substrate

2‧‧‧Light-emitting diode grains

3‧‧‧fused solder joints

4‧‧‧ Conductive metal layer

5‧‧‧The barrier layer

6‧‧‧heat layer

7‧‧‧Oxide film

S1‧‧‧Pre-processing steps

S2‧‧‧ bonding step

S2’‧‧‧Auxiliary bonding step

S20‧‧‧ film forming step

Fig. 1 is a flow chart showing the operation of the first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the first embodiment of the present invention.

Fig. 3 is a cross-sectional view showing the second embodiment of the first embodiment of the present invention.

Figure 4 is a flow chart showing the operation of the second embodiment of the present invention.

Figure 5 is a schematic cross-sectional view showing a second embodiment of the present invention.

Figure 6 is a flow chart showing the operation of the third embodiment of the present invention.

Figure 7 is a schematic cross-sectional view showing a third embodiment of the present invention.

S1. . . Pre-processing steps

S2. . . Bonding step

Claims (15)

A method for bonding a die of a light-emitting diode, comprising: a pre-processing step of heating an active solder to a temperature above a melting point of the active solder such that the active solder exhibits a molten state, wherein the active solder is added with at least one solder a bonding step consisting of coating the active solder on both ends of a substrate and heating it to a temperature above the melting point of the active solder, so that the two ends of the substrate form a molten solder joint, and then a light-emitting diode The two ends of the polar body die are respectively placed on the molten solder joints at the two ends of the substrate, so that the light-emitting diode crystal grains are cooled and solidified by the molten solder joint and adhered to the surface of the substrate; wherein the active solder is Tin-3.5 silver-0.5 copper-4 titanium (0.2% mixed rare earth), tin-0.7 silver-0.7 copper-4 titanium (0.2% mixed rare earth), indium-48 tin-4 titanium (0.2% mixed rare earth), indium- 4 Titanium (0.2% mixed rare earth) or tin-58 铋-4 titanium (0.2% mixed rare earth), and the mixed rare earth is lanthanum mixed gallium, lanthanum mixed gallium or lanthanum mixed gallium. According to the die attach method of the light-emitting diode according to the first aspect of the patent application, in the pre-processing step, the substrate is simultaneously preheated and disturbed to activate the surface of the substrate. The method of grain bonding of a light-emitting diode according to claim 1 or 2, wherein the activity of the active element is higher than that of the tin element. A method of crystallizing a light-emitting diode according to claim 1 or 2, wherein the active element is titanium, vanadium, magnesium, lithium or zirconium. According to the method of grain bonding of the light-emitting diode according to claim 1 or 2, in the pre-processing step, the ultrasonic wave assisted disturbance mode is adopted. The active material of the active solder is added to react with the non-wetting substrate and the light-emitting diode crystal grains, and at the same time, the oxide film for protecting the surface layer of the active solder is melted. According to the die attaching method of the light emitting diode according to claim 1 or 2, the bonding step is simultaneously operated by an auxiliary bonding step of coating the active solder activated by the pretreatment step. A heat dissipation layer is formed between the light emitting diode die and the substrate, and the heat dissipation layer and the molten solder joint formed at both ends of the substrate are not in contact with each other. The method for bonding a light-emitting diode according to claim 6, wherein the heat-dissipating layer is selected to have a melting point of the active solder which is lower than or equal to the melting point of the active solder selected for the molten solder joint. A method for adhering a light-emitting diode according to claim 1 or 2, wherein the molten solder joint formed by the active solder melted at both ends of the substrate is additionally bonded by electroplating or electroless plating. After a conductive metal, a barrier layer is bonded to the surface of the conductive metal to fix the soldering legs of the light-emitting diode die to the surface of the barrier layer. A method of adhering a light-emitting diode according to claim 8 wherein the conductive metal is copper, nickel, tin or a compound thereof. According to the method of grain bonding of the light-emitting diode according to claim 1 or 2, before the bonding step, a film forming step is further performed, the film forming step is performed by immersing the substrate in a modified material. A voltage is applied to the electrolyte to form an oxide film on the surface of the substrate. The method for grain bonding of a light-emitting diode according to claim 10, wherein the modified material is selected from aluminum oxide or aluminum nitride. Grain adhesion of the light-emitting diode according to claim 10 of the patent application scope A method wherein the electrolyte is sulfuric acid, chromic acid or phosphoric acid. The method for bonding a light-emitting diode according to claim 1 or 2, wherein the surface of the light-emitting diode is connected to the two electrodes by wire bonding. The method for bonding a light-emitting diode according to claim 1 or 2, wherein the end face of the light-emitting diode die bonded to the substrate forms a two electrode, and the two electrodes are contacted with the active solder. Turn on the two electrodes. The method for bonding a light-emitting diode according to claim 1 or 2, wherein the substrate is made of aluminum, copper, zirconia, ceramic, glass or aluminum nitride.