Preparation method of high performance conductive gold balls with monodispersity

Abstract

The invention relates to a preparation method of high performance conductive gold balls with monodispersity. The method comprises the steps of: (1) adding a monomer, a dispersant, an initiator and a solvent into a reaction container for a reaction of 12-24h so as to obtain polymer microspheres; (2) dispersing the polymer microspheres into a strong acid for treatment, then adding them into a polyelectrolyte aqueous solution with positive electricity; (3) dispersing the microspheres treated in step (2) into a precious metal sol, the surface of which has negative electricity; (4) conducting ultrasonic dispersing to the microspheres treated in step (3) to disperse the microspheres in an electroless gold plating bath, after the reaction, carrying out centrifugation, washing and drying, thus obtaining the high performance conductive gold balls. The method of the invention provides a solution to the problems of tin ion interference, activation under an acidic condition, complex operations and toxicity of electroless gold plating bath etc. in traditional electroless plating activation technologies. With simple preparation process, the method provided in the invention can be used for batchproduction and has good application prospects.

Description

technical field [0001] The invention belongs to the field of preparation of conductive particles, in particular to a method for preparing monodisperse high-performance conductive gold balls. Background technique [0002] Anisotropic conductive film ACF material mainly includes resin adhesive and conductive particles. The conductive particles are the core part of the ACF material. For some interconnections that require high reliability and stability, conductive particles generally use gold as the conductive shell. Patent CN 100441613C and patent US 2008 / 0078977A1 ​​propose a method for preparing conductive gold balls for ACF, both of which are formed by electroless nickel plating on the surface of polymer microspheres and then electroless gold plating. However, there are certain defects in this traditional electroless plating pretreatment process. This process requires a large amount of hydrochloric acid for sensitization and activation, and many times of washing with water...

AI Technical Summary

Problems solved by technology

However, there are certain defects in this traditional electroless plating pretreatment process. This process requires a large amount of hydrochloric acid for sensitization and activation, and many times of washing with water can remove free chloride ions. The operation is inconvenient, and the sensitization solution is easy to oxidize and dissolve. Hydrolysis fails, and the surface of pre-treated polymer microspheres is sensitized to adsorb some tin ions, which will affect the uniformity and bonding force of the coating (CN100451166C)

After electroless nickel plating, electroless metal plating is a displacement type gold plating, and the replaced metal ions (such as ferrous ions, cobalt ions, nickel ions) in the plating solution will easily cause the aggregation of microspheres; the ion concentration is as high as 10 -3 mol / L will even decompose the plating solution, resulting in the collapse of the plating solution

In addition, most of the gold salts used in the gold plating process are cyanides, which are highly toxic

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