Electroplating liquid for silver plating of etching lead frame and preparation method of electroplating liquid

Abstract

The invention discloses an electroplating solution for etching silver plating of a lead frame and a preparation method of the electroplating solution. The electroplating solution comprises 20-25 g / L of silver nitrate, 100-120 g / L of formyl hydantoin, 10-15 g / L of supporting electrolyte, 40-50 g / L of pH regulator, 200-480 mg / L of electroplating additive, 1.5-5 g / L of photoresist protective agent and deionized water, and the electroplating additive comprises 0.06-0.07 g / L of surfactant, 0.22-0.25 g / L of main brightener, 0.08-0.10 g / L of secondary brightener and 0.03-0.05 g / L of refiner. According to the invention, by adjusting the components and proportion of the plating solution, the plating solution is in a neutral or alkalescent condition, the acid-alkali corrosion of the plating solution to the photoresist is avoided, and meanwhile, by adding a certain amount of the photoresist protective agent and adjusting the use amount of the photoresist protective agent, the performance of the plating solution is not influenced, and the plating solution has the advantages of simple structure and low cost. And the photoresist on the surface of the lead frame has an anti-corrosion protection effect, so that the smoothness of pattern lines formed after the lead frame is exposed in the later period is improved.

Description

technical field [0001] The invention relates to the technical field of advanced electronic electroplating, in particular to an electroplating solution for etching lead frames and silver plating and a preparation method thereof. Background technique [0002] As the chip carrier of integrated circuits, the lead frame not only has the function of fixing the chip, but also provides leads and guide pins for welding, ensuring the solderability between the lead frame and the chip and the wire, and ensuring the electrical performance of the components. In the field of high-end electronic manufacturing , In order to obtain a chip with good conductivity, excellent solderability and high stability, it is usually necessary to plate a dense silver layer on the lead frame. [0003] First of all, the traditional lead frame silver plating is the cyanide silver plating process, which has the characteristics of good stability, high efficiency, and good maintainability. It generally works in ...

AI Technical Summary

Problems solved by technology

[0005] The existing cyanide-free silver plating systems include thiosulfate, ammonium iminodisulfonate, sulfosalicylic acid, nicotinic acid, succinimide, etc. The advantages and disadvantages of different systems are not the same, such as sulfur The sulfosulfate system is easy to prepare, with a pH value of 4.0-6.0, but the plating solution of this system cannot be stored for a long time. The working pH value of the ammonium iminodisulfonate system is 8.5-9.0, and the ammonia volatilization of the solution is serious, which is harmful to the operating environment. Ventilation requirements are high, the working pH value of the sulfosalicylic acid system is 7.0-8.0, the stability of the plating solution is good, but the cost is high, the working current density is low, etc., although 5,5-dimethylhydantoin has stability Good, wide applicability and other advantages, but the pH value of the plating solution is generally greater than 10.0, it is difficult to be directly used for etching lead frame silver plating

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