Heat-resistant silver-based dual-phase wire and method of making the same

Abstract

The invention provides an electrothermal-resistant silver-based dual-phase wire and a manufacturing method thereof. The manufacturing method of the electric heating-resistant silver-based duplex wire is to form no more than 8wt.% nano-aluminum particles in the silver wire, and make these aluminum particles evenly distributed in the silver substrate; then, plate the surface of the silver-based wire with a thickness A chromium layer less than 32nm; finally, heat-treat the silver base wire coated with chromium layer, so that the chromium ions of the chromium layer enter the silver base wire, and form an anti-oxidation layer on the surface of the silver base wire, wherein the anti-oxidation layer contains Ag2Cr phase and The AgAl7Cr phase is the electric heat-resistant silver-based duplex line.

Description

technical field [0001] The present invention relates to an electrothermal-resistant silver-based dual-phase wire and a manufacturing method thereof, in particular to an electrothermal-resistant silver-based dual-phase wire suitable for semiconductor packaging, IC packaging or light-emitting diode packaging and a manufacturing method thereof. Miscellaneous nano-pure aluminum particles enter the silver wire, and the chromium plating layer on the surface of the silver base wire is reheated to form a silver wire with Ag 2 Cr phase and AgAl 7 The Cr-phase silver-based duplex wire achieves the effect of improving the oxidation resistance and thermal stability of the silver-based duplex wire and maintaining excellent resistance to fusing current. At the same time, the residual chromium plating layer is controlled under appropriate heat treatment conditions to make it a non-plating layer. Thermal diffusion wire, which can effectively suppress the thickness of the intermetallic compou...

AI Technical Summary

Problems solved by technology

[0003] At present, common packaging wires include gold wires, copper wires, silver wires, alloy wires, etc. Taking silver wires as an example, silver is the element with the lowest resistivity among all materials, but pure silver wires are also Brittle intermetallic compounds (Ag 2 Al or Ag 4 Al); in addition, pure silver wires are prone to electrolytic ion migration (ion migration) inside the packaging material containing moisture, that is, pure silver will be hydrolyzed and dissolved by the action of an electric current to dissolve silver ions, and then react with oxygen to become unstable. Silver oxide (AgO), which will deoxidize to form silver atoms, and grow leaf texture (leaf vein) silver whiskers to the positive electrode, and finally cause a short circuit between the positive and negative electrodes; therefore, the current pure Silver wires cannot provide the ball forming and stability required by the industry; therefore, some people use silver-based alloy wires (such as copper, platinum, manganese, chromium, gold and other elements) as packaging wires, but the formed wires Still can't have the properties of low impedance and high reliability, can't pass the high temperature oxidation test, and can't improve the fusing current density; Method", providing a silver-based alloy wire rod, which is an alloy wire rod formed by at least silver, palladium, germanium and platinum, effectively improving the oxidation resistance and sulfide corrosion resistance of the silver wire rod by doping an appropriate amount of palladium (Pd) At the same time, due to its extremely low diffusion rate and the barrier properties of surface products, it can avoid the ion migration problem of silver, and also has an inhibitory effect on the metal reaction between the silver and aluminum pads; and an appropriate amount of germanium (Ge) can effectively improve the wire material. In addition, an appropriate amount of platinum (Pt) can enhance the oxidation resistance, sulfidation and chloride ion corrosion of the wire, and it also has a significant inhibitory effect on the migration of silver ions , and also reduce the formation of intermetallic compounds between the silver alloy wire and the aluminum pad; When the content of germanium is too high, the resistance of the alloy wire will increase, and when the content of germanium is too high, the ductility of the wire will be reduced; It is not easy to maintain the consistency of reliability; in addition, the above-mentioned wires cannot pass the high-temperature oxidation test, and there is no effect of increasing the fusing current density

[0004] In addition, in order to solve the problem of easy oxidation of pure silver bonding wires, some people have proposed to plate other metal coatings on its surface to improve oxidation and corrosion. Please also refer to Nippon Steel Advanced Materials Co., Ltd. and Nippon Steel Micrometals Co., Ltd. Co., Ltd. applied for a series of Taiwan invention patents related to junction wires for semiconductor devices, "junction wires for semiconductor devices" disclosed in announcement No. I342809, "junction wires for semiconductor devices" disclosed in announcement No. I364806, and announcement No. I364806 The disclosed "bonding wires for semiconductors", the "copper alloy bonding wires for semiconductors" of publication No. 201107499, the "copper bonding wires for semiconductors and its bonding structure" of publication No. Bonding structure”; the above-mentioned bonding wire structure is generally provided with a skin layer (which can be composed of palladium, ruthenium, rhodium, platinum and silver) on the surface of the core material (which can be composed of metals such as copper, gold, and silver) As a result, the above-mentioned bonding wires often have the following defects in actual implementation and use: (a) Because the surface of the metal-plated wire has a skin layer, the hardness is relatively high, and the process current is not easy to control, which often leads to uneven thickness of the coating, resulting in packaging The overall output rate of the process is poor and the yield rate is low; (b) silver or silver alloy is plated with a palladium layer during electric frame off (EFO), and the palladium layer on the surface makes the ball (free air ball, FAB) The hardness of the center of the ball is too hard, resulting in insufficient strength of the neck above the solder ball. After wire bonding (WB), the neck fracture problem often occurs, which leads to the problem of peeling off the joint interface; and the palladium element in the solder ball It also has the problem of segregation. The difference in the structure of the ball part affects the wire bonding conditions; moreover, the wire cannot maintain the surface oxidation resistance in a high temperature environment, and the ball needs to be protected by an atmosphere, otherwise it cannot be balled and played. Wire

[0005] In addition, the general bonding wires must be protected by molding with thermosetting plastics (such as epoxy resin (EPOXY) after bonding; however, epoxy resin materials will be exposed to high temperature or long-term lighting of diode components. Problems such as photodegradation or yellowing occur, which cannot meet the quality requirements of the LED packaging industry process reliability, and the wire cannot effectively inhibit the erosion of negative ions on the surface and maintain the stability of long-term high-humidity and high-heat environments

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