CN-116475624-B - Die-bonding solder paste capable of passing through air reflow soldering and preparation method thereof

Abstract

The invention discloses a die-bonding soldering paste capable of being subjected to air reflow soldering and a preparation method thereof, wherein the die-bonding soldering paste consists of 15% of Sn96.5Ag3.0Cu0.5 alloy soldering powder with the size of 2-25 um and 85% of nano-processed soldering paste; the soldering paste comprises the following components in percentage by mass: 40-50% of solvent, 35-40% of resin, 5-8% of imidazole, 5-10% of thixotropic agent and 1-5% of antioxidant; the tin powder is high in sphericity, smooth in surface, low in oxygen content of tin powder and capable of being subjected to ultrasonic atomization, the adsorption film type organic matter is preferably added to the tin powder, the imidazole and the phenolic antioxidant with complex metal ions are preferably added, meanwhile, the nano grinding machine is used for carrying out nano grinding treatment on the soldering paste, the surface of the tin powder can be completely wrapped by the nano ground soldering paste, and a nano material protective layer is formed.

Inventors

• He Kangqiang
• SU JUN
• YANG YANG

Assignees

• 思特迪新材料科技(深圳)有限公司

Dates

Publication Date

20260505

Application Date

20230323

Claims (6)

1. 1. A die-bonding soldering paste capable of being subjected to air reflow soldering is characterized by comprising, by mass, 85% of Sn96.5Ag3.0Cu0.5 alloy soldering powder with the size of 2-25um and 15% of nano-treated soldering flux, wherein the soldering flux comprises, by mass, 40-50% of a solvent, 35-40% of a resin, 5-8% of imidazole, 5-10% of a thixotropic agent and 1-5% of an antioxidant, the imidazole is one or a combination of 2-ethylimidazole, 2-methylimidazole, 2-ethyl 4-methylimidazole and 2-phenylimidazole, and the thixotropic agent is one or a combination of two of hydrogenated castor oil and modified hydrogenated castor oil.
2. 2. The method of claim 1, wherein the solvent is one or a combination of diethylene glycol mono-octyl ether and diethylene glycol hexyl ether.
3. 3. The method of claim 1, wherein the resin is one or more of lead-free 685 rosin, water-white rosin, and hydrogenated rosin glycerol ester.
4. 4. A die attach solder paste for solder reflow by air as claimed in claim 1, wherein: the antioxidant is one or more of antioxidant BHT, antioxidant 1024 and antioxidant 245.
5. 5. The method for preparing the die-bonding soldering paste capable of being subjected to air reflow soldering according to claim 1, which is characterized by comprising the following steps of weighing a solvent, resin, imidazole, a thixotropic agent and an antioxidant according to mass percent, adding the solvent, the resin, the imidazole, the thixotropic agent and the antioxidant into a reaction kettle, heating to 100 ℃ while stirring, sealing after complete dissolution, standing at room temperature for 24 hours, grinding for 2 times by using a nano grinder, and controlling the particle size of all materials in the soldering paste to be less than nano level to prepare the required nano soldering paste; And secondly, stirring the prepared nano soldering paste and ultrasonic atomized soldering powder in a tin paste stirrer for more than 0.5 hour in vacuum, setting the vacuum degree to be 0.1 MPa, setting the stirring rotating speed to be 20rpm/min, and completely and uniformly stirring.
6. 6. The method of claim 5, wherein the ultrasonic atomized 2-25um Sn96.5Ag3.0Cu0.5 alloy solder powder is prepared by forming liquid solder solution into fine droplets in a protective atmosphere by ultrasonic vibration.

Description

Die-bonding solder paste capable of passing through air reflow soldering and preparation method thereof Technical Field The invention belongs to the technical field of welding, and particularly relates to a die-bonding solder paste capable of being subjected to air reflow soldering and a preparation method thereof. Background At present, the high-power LED has the advantages that the market scale is increased due to the excellent performance, so that the LED can be applied to the lighting market, and the LED is expanded to brand new fields of automobiles, mobile phones, medical treatment and the like. However, in the practical use process, the high-power LED device can only convert 15% -20% of input power into electric energy, the rest of the high-power LED device can dissipate in a heat form, along with miniaturization of the device and increase of power, the red shift of an emission spectrum of a chip can be caused, so that the optical power of the LED can be reduced, ageing of the device and attenuation of permanent light are accelerated, in order to better reduce the heat dissipation problem of the LED device, researchers develop a novel packaging connection material, namely a die-bonding solder paste, on the basis of die-bonding glue and conductive silver glue, and after the die-bonding solder paste is welded, a reliable third phase can be formed between a silver plating layer on a ceramic substrate and a gold layer at the bottom of the chip, so that the heat dissipation of the device is very beneficial. The die bonding solder paste with high thermal conductivity can replace die bonding glue and conductive silver glue which are widely used before, so that the heat dissipation problem of a chip is well solved, and the normal use of a high-power LED is met. In the design of the die bonding solder paste, in order to meet the welding of high-power wafers in the range of 10-75 mil, alloy soldering powder with a powder diameter of 2-25um and Sn96.5Ag3.0Cu0.5 is generally adopted. Because the diameter of the metal tin powder is smaller, the larger the specific surface area is, the higher the oxygen content of the surface of the tin powder is, and the current solid crystal tin paste is applied on the surface to be welded in a dispensing or printing mode, usually, 2-12 hours are required for reflow soldering, the tin powder is exposed in an oxygen environment for a long time, and the tin powder is easily oxidized by oxygen in the air, so that the wettability of the tin paste is affected. At present, the method of introducing nitrogen into the solder paste by reflow soldering is required to reduce the concentration of oxygen in the soldering process, and prevent reoxidation in the soldering process, thereby reducing the oxidation of the surface of the tin powder and ensuring the wettability of the solder paste during soldering. Chinese publication No. CN102069314A discloses a solid-state solder paste for high-power LEDs and a preparation method thereof, wherein the solid-state solder paste is prepared by mixing lead-free metal alloy powder and solid-state solder paste, has higher thermal conductivity, shorter solid-state time and stable performance, and the preparation method is simple, and the prepared solid-state solder paste has particularly good wettability to a gold layer, low porosity, uniform and fine paste, no peculiar smell, high thixotropic index and excellent welding strength and mechanical property. Chinese patent publication No. CN105855748A discloses a die-bonding solder paste for chip package, a preparation method and a use process thereof, and the die-bonding solder paste can effectively ensure the uniformity of long-term operation of the die-bonding process in an open environment, improve oxidation resistance, reduce void ratio and improve the electrical property of a semiconductor device. In view of the existing invention patent and core technology of market products, the welding of the prepared die-bonding solder paste at present is completed by adopting a nitrogen gas introducing method in the reflow soldering process. The method has the defects that the use amount of nitrogen is increased, and the production cost is increased. Disclosure of Invention The invention aims to provide a die-bonding solder paste capable of being subjected to air reflow soldering and a preparation method thereof, so as to solve the problems in the prior art. The invention provides a die-bonding soldering paste capable of being subjected to air reflow soldering, which comprises, by mass, 40-50% of a solvent, 35-40% of a resin, 5-8% of imidazole, 5-10% of a thixotropic agent and 1-5% of an antioxidant, wherein the die-bonding soldering paste is composed of 15% of Sn96.5Ag3.0Cu0.5 alloy soldering powder with the size of 2-25um and 85% of a nano-treated soldering flux. A method for preparing solid-state soldering paste capable of passing through air reflow soldering is characterized by comprising the following steps of