Electroless Plating Automatic Liquid Replenishment Method

Abstract

The application of the present invention relates to the technical field of surface treatment, and discloses an automatic liquid replenishment method for electroless plating, 1) detecting the pH value of the plating solution through a pH meter, and the pH meter automatically transmits the detected pH value signal to the control electric box; 2) controlling The electrical box sends corresponding control signals to the metering pump according to the pH value signal to control the opening and closing of the metering pump; the control electrical box is preset with a pH initial value for instructing the metering pump to start working and a calculation for calculating the amount of fluid replacement Formula; 3) When the metering pump starts, the two-way metering pump extracts the liquid A for adjusting the pH of the plating solution and the liquid B for adjusting the composition of the plating solution. After the liquid A and the liquid B are preheated respectively, Enter the plating tank from the auxiliary tank. The above automatic liquid replenishment method for electroless plating can realize automatic synchronization of plating, detection and liquid replenishment, and the detection and liquid replenishment are very accurate.

Description

technical field [0001] The invention relates to the technical field of surface treatment, in particular to an automatic liquid replenishment method for electroless plating. Background technique [0002] Electroless plating, also known as electroless plating, is a plating method that reduces metal ions in the plating solution to metal and deposits them on the surface of various materials or parts with the help of a suitable reducing agent without an external current. Compared with electroplating, electroless plating has the characteristics of uniform plating, small pinholes, no need for DC power supply equipment, deposition on non-conductors, and plated parts are not limited by size and shape. [0003] The deposition rate of electroless plating solution is mainly affected by the operating temperature during plating, the concentration of metal ions in the plating solution, the concentration of reducing agent and the pH of the plating solution. In order to ensure the depositio...

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Problems solved by technology

[0005] Although the above-mentioned photoelectric colorimetry can realize automatic replenishment, there are also some technical problems as follows: 1) as the electroless nickel plating plating time increases, impurities in the plating solution gradually increase, and naturally the impurities of the tested solution also increase, and the impurities will increase. Affect the luminosity and color, and then interfere with the normal detection of the tested liquid by photoelectric colorimetry, so the sensitivity becomes lower and the accuracy of liquid replenishment decreases; Input into the plating tank, it will cause the local temperature difference in the plating tank to be too large, and at the same time cause the local pH of the plating solution to be too high, which will easily produce nickel hydroxide precipitation and increase the instability of the plating solution; 3) during the sampling process, the suction of the liquid pump The plating solution produces a large amount of foam, so the tested solution drawn from the plating solution will contain a large amount of foam, and neither the sampling device nor the detection device can strictly remove these foams, which requires frequent adjustment of the sensitivity of the detection device, which will affect the detection As a result, the accuracy of rehydration is reduced; 4) The amount of each replenishment liquid needs to be estimated, that is, the empirical formula needs to be replaced frequently

In the process of electroless nickel plating, the reduction center on the tank wall and the catalytic particles in the plating solution will cause nickel reduction, and the excessive local temperature difference of the plating solution will easily cause the precipitation of nickel ions, so the consumption range of nickel ions cannot be accurately estimated. In addition, changes in the concentration of nickel ions and other complex ions in the plating solution will affect the utilization rate of hypophosphite ions, so the consumption range of hypophosphite ions cannot be accurately estimated.

In summary, the existing technology for automatic liquid replenishment in electroless plating cannot accurately estimate the consumption of various reactants in the plating solution, nor can it automatically synchronize plating, detection, and liquid replenishment, let alone accurately detect and accurately replenish liquid

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