Working liquor supplementing method for pulse copper plating process

Abstract

The invention discloses a working liquor supplementing method for a pulse copper plating process. The method comprises the following steps: taking 8-12% of the total volume of tank liquor in a workingtank every 25-35 days, filtering the tank liquor by a membrane filtration system to obtain clear liquor and concentrated liquor, adding a proper amount of an inhibitor and a leveling agent into the clear liquor to serve as new working liquor to be supplemented to the working tank, and discharging the concentrated liquor, wherein the membrane filtration system is used for filtering and separatingsubstances with the molecular weight of 500 or above. According to the working liquor supplementing method disclosed by the invention, part of the tank liquor is filtered by the membrane filtration system to obtain the clear liquor, decomposition products of the inhibitor and the leveling agent which are harmful to an electroplating system in the tank liquor are smoothly removed, the inhibitor andthe leveling agent are added into the clear liquor to serve as the new working liquor to be supplemented to the working tank, waste of sulfuric acid, copper sulfate and a brightener is avoided, lotsof wastewater treatment and resource waste are reduced, and meanwhile, the operation time and labor are saved.

Description

technical field [0001] The invention relates to a method for supplementing working fluid for pulse copper plating process. Background technique [0002] The traditional circuit board through-hole copper plating process uses vertical line and vcp line DC electroplating. Due to the characteristics of DC electroplating, the thickness of deposited copper in the high current density area is greater than that in the low current density area. Currently, in the case of high current density or high In the case of DC electroplating of circuit boards with an aspect ratio, the ratio of the thickness of the electroplated copper in the hole to the thickness of the electroplated copper on the copper surface outside the hole is about 75%-85%. Since the through-hole electroplating process requires only the copper plating in the hole, When the copper plating layer in the hole reaches the thickness requirement, a large amount of wasted copper plating layer is deposited on the copper surface, a...

AI Technical Summary

Problems solved by technology

With the electroplating production, these inhibitors and leveling agents show inhibitory and leveling effects due to electrochemical principles, and at the same time, they will be decomposed from large molecules into relatively small molecular decomposition products, and these decomposition products not only no longer It has inhibitory and leveling effects, and enrichment in the bath solution will affect the conductivity and current efficiency of the working solution, and may be mixed with other substances to form a gel-like substance that sticks to the surface of the circuit board to be electroplated, causing defects

[0004] Therefore, the current operation is to discharge 10% of the old working fluid every month of production, and add 10% of the newly opened working fluid (which contains a certain proportion of sulfuric acid, copper sulfate, water, inhibitors, leveling agents, etc.) , brightener), in order to dilute the concentration of decomposition products in the working solution and reduce the impact of decomposition products on normal electroplating. In addition to a small amount of additives, the working solution contains a large amount of sulfuric acid, copper sulfate and water, so this Although the operation reduces the concentration of a small amount of decomposition products, it will bring a lot of waste of sulfuric acid and copper sulfate, as well as the waste generated by the treatment of wastewater containing sulfuric acid and copper sulfate; open cylinder

Such a process of removing organic decomposition products together with sulfuric acid, copper sulfate and other working fluids will obviously cause a lot of waste of materials and produce a lot of waste water in the face of pulse copper plating with tens of thousands of liters of bath solution.

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