Copper Electroplating Solution and Copper Electroplating Process

Abstract

The present disclosure relates to a copper electroplating solution and a copper electroplating process. The solution includes following components: 20 to 240 g/L of copper sulfate pentahydrate, 20 to 300 g/L of sulfuric acid, 25 to 120 mg/L of chlorine ion, 0.1 to 20 mg/L of a brightener, 1 to 2000 mg/L of an inhibitor, and the balance is deionized water; The brightener is selected from two of the group consisting of alkyl sulfonic acid thiols and derivatives thereof; the inhibitor is selected from one or more compounds of non-ionic surfactants. The solution of this disclosure can greatly improve the current density of plating and the throwing power (TP) of electroplating of the through hole of flexible boards, wherein the TP value can reach more than 200%, and the electroplating deposited copper layer in the hole is flat and the quality thereof meets the requirements of the flexible board.

1 . A copper electroplating solution, comprising the following components:
 copper sulfate pentahydrate: 20 to 240 g/L   sulfuric acid: 20 to 300 g/L   chlorine ion: 25 to 120 mg/L   brightener: 0.1 to 20 mg/L   inhibitor: 1 to 2000 mg/L   deionized water: balance;   wherein, the brightener is selected from two of the group consisting of alkyl sulfonic acid thiols and derivatives thereof; the inhibitor is selected from one or more of non-ionic surfactants.   
     
     
         2 . The copper electroplating solution according to  claim 1 , wherein the brightener is bis-(sodium sulfopropyl)-disulfide and sodium N, N-dimethyl dithiocarboxamide propanesulfonate. 
     
     
         3 . The copper electroplating solution according to  claim 2 , wherein the bis-(sodium sulfopropyl)-disulfide is added at an amount of 0.1 to 10 mg/L; the sodium N, N-dimethyl dithiocarboxamide propanesulfonate is added at an amount of 0.1 to 10 mg/L. 
     
     
         4 . The copper electroplating solution according to  claim 3 , wherein the sum of the added amount of bis-(sodium sulfopropyl)-disulfide and the added amount of sodium N, N-dimethyl dithiocarboxamide propanesulfonate is greater than 0.5 mg/L, the absolute value of the difference between the added amount of bis-(sodium sulfopropyl)-disulfide and the added amount of sodium N, N-dimethyl dithiocarboxamide propanesulfonate is more than 0.5 mg/L. 
     
     
         5 . The copper electroplating solution according to  claim 4 , wherein the sum of the added amount of bis-(sodium sulfopropyl)-disulfide and the added amount of sodium N, N-dimethyl dithiocarboxamide propanesulfonate is greater than 1 mg/L and less than 6 mg/L. 
     
     
         6 . The copper electroplating solution according to  claim 1 , wherein the inhibitor is selected from one or more of the group consisting of polyalkylene glycol compounds, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, polyethylene glycol stearate, alkoxy naphthol, oleic acid polyglycol ester, poly (ethylene glycol-propylene glycol) random copolymer, poly (polyethylene glycol-polypropylene glycol-polyethylene glycol) block copolymer, poly (polypropylene glycol-polyethylene glycol-polypropylene glycol) block copolymer, and the inhibitor is added at an amount in the range of 1 to 2000 mg/L. 
     
     
         7 . A copper electroplating process for flexible printed circuit board, comprising pretreatment procedure, first copper electroplating procedure, rinsing procedure, second copper electroplating procedure and post treatment procedure;
 wherein the copper electroplating solution according to  claim 1  is used in the first copper electroplating procedure;   a second copper electroplating solution is used in the second copper electroplating procedure, and the second copper electroplating solution includes the following components:   copper sulfate pentahydrate: 20 to 240 g/L   sulfuric acid: 20 to 300 g/L   chlorine ion: 25 to 120 mg/L   second brightener: 0.1 to 20 mg/L   second inhibitor: 1 to 2000 mg/L   leveling agent: 5 to 40 mg/L   deionized water: balance;   wherein the second brightener is selected from one of the group consisting of bis-(sodium sulfopropyl)-disulfide, sodium mercaptopropanesulfonate, 2-mercaptobenzimidazole and ethylene thiourea; the second inhibitor is selected from one or more of the group consisting of polyalkylene glycol compounds, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, polyethylene glycol stearate, alkoxy naphthol, oleic acid polyglycol ester, poly (ethylene glycol-propylene glycol) random copolymer, poly (polyethylene glycol-polypropylene glycol-polyethylene glycol) block copolymer, poly (polypropylene glycol-polyethylene glycol-polypropylene glycol) block copolymer; and the leveling agent is selected from one or more of the group consisting of polyethylenimine or derivatives thereof, caprolactam or derivatives thereof, polyvinyl pyrrole or derivatives thereof, diethylenetriamine or derivatives thereof, hexamethylenetetramine or derivatives thereof, dimethyl phenylpyrazolone onium salt or derivatives thereof, rosaniline or derivatives thereof, sulfur-containing amino acids or derivatives thereof, phenazine onium salt or derivatives thereof.   
     
     
         8 . The copper electroplating process for flexible printed circuit board according to  claim 7 , wherein process parameters of the first copper electroplating procedure are: 1 to 5 A/dm 2  of current density, 15 to 32° C. of electroplating temperature, and 20 to 120 mins of electroplating time; process parameters of the second copper electroplating procedure are: 1 to 5 A/dm 2  of current density, 15 to 32° C. of electroplating temperature, and 1 to 20 mins of electroplating time. 
     
     
         9 . A flexible printed circuit board prepared by the copper electroplating process according to  claim 7 . 
     
     
         10 . The flexible printed circuit board according to  claim 9 , wherein the flexible printed circuit board is provided with a micro through hole having a size of 20 to 300 μm in diameter and 40 to 300 μm in board thickness.