Plating solution carrying out chemical palladium plating on copper surface and preparation method therefor

Abstract

The invention discloses a plating solution carrying out chemical palladium plating on a copper surface and a preparation method therefor. A liter of the plating solution is composed of 1-5g of PdCl2, 60-200ml concentrated ammonia liquor, 2-20g of NaH2PO2.H2O, 0-40g of NH4Cl, 5-50ml of isopropanolamine and 0-100mg of bismuth chloride, the balance being distilled water. The preparation method is as follows: ammonium chloride, bismuth chloride and the isopropanolamine are added into concentrated ammonia liquor, then palladium chloride is added slowly with stirring, the mixture is allowed to stand for 24h, then NaH2PO2.H2O is added slowly with stirring, then distilled water is added, and a plating solution carrying out chemical palladium plating on a copper surface is obtained. The plating solution has a stable pH and excellent bath lotion stability, induction time and plating time are shortened, the deposition rate is raised, and the obtained plating is uniform, compact and smooth, and has no cracks or pores.

Description

technical field [0001] The invention relates to a plating solution for electroless palladium plating on a copper surface and a preparation method thereof, belonging to the metal surface treatment industry. Background technique [0002] In the field of electronics, copper is a very good conductive material. It is often used as the base material for circuit production. The application of copper wire bonding in the electronic packaging process also tends to replace gold wires as the price of gold wires rises. Large-scale packaging factories are increasing their Large investment in copper wire process. Compared with gold wire, copper wire has better electrical and mechanical properties, so the same product can use smaller diameter copper wire for bonding, and it is more suitable for small chip pads, narrow spacing and long bonding distance packaging products. However, the pollution and oxidation on the surface of the single crystal copper bonding wire lead to a decrease in sol...

AI Technical Summary

Problems solved by technology

However, the pollution and oxidation on the surface of the single crystal copper bonding wire lead to a decrease in soldering performance, and the oxide film reduces the ball forming, bonding performance and reliability of the copper wire. In order to prevent the oxidation of the copper wire and further improve the bonding performance, a certain Method Plating a layer of palladium film on the surface of copper wire is a better solution

[0003] The electroless palladium plating and electroplating palladium plating processes reported in the current literature and patents are relatively complicated, and the electroless palladium plating must go through cumbersome sensitization and activation steps, and requires a long plating time

In the plating solutions described in patent documents CN101228293A and CN101440486A, the reducing agent is mostly toxic hydrazine or hydrazine derivatives, and with the consumption of hydrazine in the plating tank, the plating speed drops sharply

In the system using palladium ammonium complex and ammonium chloride as a stabilizer, at a higher temperature, the volatilization of ammonia will cause a sharp change in pH in the plating tank, which is not conducive to industrial production

Moreover, due to the high internal stress of hydrogen in the palladium coating, it is easy to produce cracks when it is thick, and it will cause instantaneous cracks and delamination when the sample is removed from the plating solution.

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