The Research Of Electroless Copper Plating On Nylon Fabrics With Sodium Hypophosphite As Reductant

After half a century of development, electroless copper plating technology has been widely used in electronics, machinery, aerospace and other industrial areas. At the present time, electroless copper plating technology is preliminarily used in the electromagnetic shielding fabrics due to metal plating fabrics are possessed of excellent conductivity and exceptional structure. Whereas, the stability of traditional electroless copper plating technology with formaldehyde bath is poor and more seriously, formaldehyde which has been forbidden by many countries is volatile, toxic and unfriendly to the environment. At the same time, electroless copper plating solution with sodium hypophosphite as reducing agent is stable in property, non-toxic and friendly to the environment, also safe in production process. Because of these advantages, it is expected to replace the formaldehyde in electroless copper plating. But so far, the study on electroless copper plating process with sodium hypophosphite as reducing agent applied in the textile field is not sufficient.Hence, this paper adopts the nylon fabric as the substrate, with application of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and other modern characterization techniques, to study the electroless copper plating process with sodium hypophosphite as reducing agent systematically. The target of this paper is to choose the optimal control parameters of the process to improve the property of the electromagnetic shielding fabrics which own perfect fabric wearability also. Also, this paper preliminarily studied the influence of the magnetic field on electroless copper plating process and coating quality. This paper mainly studies on the following aspects:1. Research for the optimal pre-treament process parameters for the electroless copper plating process with sodium hypophosphite as reducing agent from the angle of environment-friendliness;2. Analyse the factors which impact the deposition rate in order to get the superlative electroless copper plating basic process through orthogonal experiments; 3. Focuse on analysing and studying the influence of nickel sulfate concentration, temperature and pH value on chemical copper plating process. Studies showed that: nickel sulfate played a vital role on electroless copper plating process. On the one hand, electroless copper deposition rate increases with the increase of the nickel sulfate concentration, On the other hand, excess concentration will result in black, rough surface as well as the decline of the conductivity of electroless copper plating layer. Also, the effect of the temperature and pH value showed the same trend with the nickel sulfate concentration;4. The particles of copper coating surface obtained from the basic process are granular, whose size is comparatively uneven, so the additive is essential to improve the coating surface morphology. Coating is chactercopper-nickel alloy with the structure of face-centered cubic which possesses (111), (200), (220), (311) and (222) crystal face diffraction peaks;5. The results of the study on the effects of additives on copper plating show that: potassium ferrocyanide, 2,2'-bipyridyl and benzene sodium are three effective additives in electroless copper plating process. Potassium ferrocyanide and 2,2'-bipyridine have the similar effction on deposition rate: With the increased concentration of additive, the deposition rate presents to rise first and then drop when it reaches a certain extreme points. Experimental results also show that benzene sodium can reduce the rate of electroless copper deposition. Through the research, it is known results that the role of mixing additives more effective than a single additive;6. The study indicates that after adding additives, coating particles change smaller and voids between the particles become smaller while particles arranges more closely which results in the increasing of the coating gloss. It is found that the content of copper in coating is significantly increased;7. The surface resistance of electroless copper plating nylon fabric which adding mixed additives reduces from 0.34Ω/cm to 0.28Ω/cm and the fluctuations is low. After adding mixed additives, coating distributes evenly and coating adhesion has been improved;8. In the magnetic field, deposition rate increases from 2.25g/(m~2·min) to 3.04g/(m~2·min), coating particles become smaller and arranges in dense; In coating, copper content increases from 90.02% to 93.97% and phosphorus content decreases from 5.06% to 1.28%. The results of the research also show that copper plating nylon fabric surface resistance reduces from 0.28Ω/cm to 0.245Ω/cm and electrical conductivity enhances;9. Researches on the performance of electroless copper plating nylon filament and fabric show that: after electroless copper plated, the initial modulus of nylon filament increases; breaking strength and breaking elongation declines. After electroless copper plated, bursting strength of nylon fabric decreases and wear resistance reduces; bending rigidity increases which results in the handle harden; permeability and moisture permeability decreases. Therefore, it is recommended that in practical applications, electroless copper plating nylon filament can be blended or interwoven with other types of yarn, which can make the fabric not only has good electrical conductivity, but also maintain a good wearability.