Process of electroless plating Cu-Sn-Zn ternary alloy Process of electroless plating Cu-Sn-Zn ternary alloy

Process of electroless plating Cu-Sn-Zn ternary alloy

  • 期刊名字:中国有色金属学会会刊(英文版)
  • 文件大小:754kb
  • 论文作者:HE Xin-kuai,CHEN Bai-zhen,HU G
  • 作者单位:School of Packaging and Printing,School of Metallurgical Science and Engineering
  • 更新时间:2020-11-22
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论文简介

Available online at www.sciencedirect.comTransactions ofSCIENOE鄂*@oiner.NonfSociety of Chinarous MetalsScienceTrans. Nonferrous Met. Soc. China 16(2006) 223-228Presswww.csu.cdu.cn/ysxh/Process of electroless plating Cu-Sn- Zn ternary alloyHE Xin-kua(何新快).2, CHEN Bai-zhen(陈白珍)尸, HU Geng -sheng(胡更生)'DENG Ling-feng(邓凌峰)',2, ZH0U Ning-bo(周宁波)尸, TIAN Wen-zeng(田文增)尸1. School of Packaging and Printing. Zhuzhou Institute of Technology, Zhuzhou 412008, China;2. School of Metallurgical Science and Engineering, Central South Universit, Changsha 410083, ChinaReceived 15 January 2005; accepted 4 October 2005Abstract: Cu-Sn-Zn temary alloy layer with 10 pμm thickness was prepared through elctroless plating method. The infuences ofprocess conditions including the concentration of matllic salts, reductant and complex agent on Cu-Sn-Zn aloy were studied in details.The stability to bear color changes and corrosion resistance of Cu-Sn-Zn film layer were studied through air-exposure experiment andeletrochemical analyses test respectively. The results show that the performances of Cu-Sn-Zn flm layer are obviouslysuperior to brassmatrix. By use of SEM,EDS and XRD, the morphology, microstnucture and chemical composition were investigated. The results showthat complex agent can increase the content of Sn and Zn, improve the evenness and compactness and decrease needle holes, thereforethe properties of electroless plating layer such as the stability to bear color changes and corrosion resistance are improved remakably.The probable mechanism of complex agent was discussed.Key words: electroless plating: Cu-Sn-Zn temary aly;, color-change resistance; corrosion resistance10 pum thickness was sucessfully prepared on brass1 Introductionsubstrate, which did not fade when exposed in air aftera year, and showed better corrosion resistance thanElectroless plating tin and tin alloy is anbrass substrate.attractive technique to produce function plating layerwith prior performances of corrosion resistance and2 Experimentaldecoration[1, 2], due to the possibility of uniformdeposition on complex shapes, conductive and2.1 Materials and electroless platingnon-conductive substrates, hardness and relativelyThe matrix used was brass(H65), whose size wassimple equipment[3- 7]. At present, these plating40 mmX 20 mmX2 mm. Electroless baths werelayers are applied in many fields, such as chemicalprepared using analytic grade reagents and distlledindustry, machinery, electron and spaceflight. A lot ofwater. Brass substrates were polished mechanically todomestic and overseas scientific workers are interestedmiror bright finish and degreased in acetone solution.in electroless plating tin, especially in electrolessBefore electroless plating, the substrates wereplating tin binary alloy[8- 12]. But the study ofactivated in a 10% H2SO4 solution. After each of theseelectroless plating tin ternary alloy is relatively lttle,pretreatment steps the substrates were cleaned irand the study of Cu-Sn-Zn termary alloy electrolessdistilled water, Electroless plating was performed forplating is still not reported. The electroless plating tin10- 15 min at room temperature in electroless bathbinary alloy layers, for example Cu-Sn plating layer,containing: CuCl 12 g/L, SnCl2 20 g/L, ZnCl2 40 g/L,have bad stability to bear color changes, from gold toNaH2PO2 40 g/L, HC 180 mL/L, HsCOONa 25 g/L,gray, appearing dark spots,and so on[13- 16]. Tocomplex agent A 25 g/L, complex agent B 0.15 g/L,solve these problem, it is necessary to develop a newpH 4- 5. During electroless deposition the bath wasprocess to obtain Cu-Sn-Zn temary alloy electrolessagitat中国煤化工plating layer, which does not fade and has bettercorrosion resistance than binary alloy. In this study,.2!YHCN M HG and analyses ofCu-Sn-Zn temnary alloy electroless plating layer withelectroless plating layerFoundation item: Projcec(04J140036)Supported by the Naturl Science Foundation of Hunan Province. ChinaCorrespondimg autbor: HE Xin-kuai; Tel: +86 731-8876621; F-mail: h-xk@ 163.com224HE Xin-kuai, ct al/Trans. Nonferrous Met. Soc. China 16(2006) 223-228KYKY2800 SEM was used to observe thea)■-Snmorphology of Cu-Sn-Zn electroless plating layer, thecomposition of layer was analyzed by EDS. The0tthickness was measured by the following formula:d=(m2- m)SXp. Where m2, m are respectively thmass of Cu-Sn-Zn ternary alloy electroless plating咨35-specimen and substrate; S is the area of the electrolessplating specimen; ρ=p(Cu) X w(Cu)+p(Sn) X w(Sn)+p(Zn)X w(Zn) (Cu)=8.9 g/cm', p(Sn)=7.29 g/cm',卡20个p(Zn)=7.09 g/cm', w is the mass fraction of Cu, Sn, Znin the alloy). The stability of the layer to bear colorchanges was studied through air-exposure experiment4812620by observing its rate of color and luster alteration inp(CuCl2)(g.L-1)room, and the corrosion resistance of the layer wasinvestigated through electrochemical analyses test in" (b)1 mol/L H2SO4, 3.5% NaCl and 10% NaOH solution0-respectively using electrochemical work stationCHI600b. Cu-Sn-Zn plating layer was used as workelectrode, the large area platinum slice as auxiliaryelectrode, and the reference electrode was a saturatedcalomel electrode (SCE).0}3 Results and discussion0叶3.1 Influences of main salts152550The important function of main salts(CuCl2,SnCl2 and ZnCl2) in bath is to provide Cu2+, Sn2+ andρ(SnCl2)(g.L))Zn~* in the process of electroless deposition, and their(e)"concentrations have great influences on the composi-tions and performances of Cu-Sn-Zn ternary alloy. In3order to obtain their influences simply and effectively,50■-Snthe method of keeping other compositions unchangingand only changing one of the concentrations of Cu2*,另40.-CuSn*+, Zn2*, reductant and complex agent respectivelywas adopted, and the results are shown in Fig. l.Theoptimum content of salts, reductant and complex agent20 tin bath was determined by air- exposure experiment,electrochemical analyses and deposition rate test.0卜As shown in Fig.1, the contents of Cu, Sn and Zn012630 40 5(66in the Cu-Sn-Zn alloy increase respectively with thep(ZnCl2)(g.L~)increasing of main salts(CuCl2, SnCl2 and ZnCl2)concentration, but the increasing rate of Cu is fasterFig,1 Influences of concentration of salt on composition ofthan those of Sn and Zn, because Cul+ is easier toCu-Sn-Zn aloy: (a) p(SnCh)=20 g[, p(ZnCl)=40 g/L; (b)obtain the electrons provided by reductant to depositp(CuCl2)=12 g/L, p(ZmCl)=40 g/L; (C) p(CuCl2)=12 g/L,on brass substrate than 5n2+ and Zn2*. Figs. 1(b) and (C)p(SnCl)=20 g/indicate that Cu content decreases when the mainsalts(SnCl2, ZnCl2) concentrations increase respec-is over 20 g/L, Sn and Zn contents, especially Sn (3%),tively, but its content almost does not change when theare very ltte. The Cu-Sn-Zn alloy containingmain salts(SnCl2, ZnCl2) concentrations are over 16dif中国煤化工- was exposed in air tog/L and 10 g/L. However, Sn and Zn contentstest: changes. The resultsrelatively increase or decrease with the main saltshoYHCN M H Gn contents are over(SnCl2, ZnCl2) concentration increasing respectively.43%(mass fraction), it is still bright after a year'sAt last Sn and Zn contents maintain stable. Theexposing. While the color of the alloy, of which Snexperiments also show that when CuCl2 concentrationand Zn contents are less than 40%,changes fromHE Xin-kuai, et al/Trans. Nonferrous Met Soc. China 16(2006) 223-228225platinum to gray, and dark spots appear on its surfaceto obtain the electrons is increased. This leads to theafter half a year, and when Sn content is less than 6%,increasing content of Sn and Zn. Considering theit is seriously faded in one or two months. So, thecomposition and the deposition rate, the optimumoptimum concentrations of CuCl2 , SnCl2 and ZnCl2 inconcentration of NaH2PO2 is 40 g/L.the bath are 12 g/L, 20 g/L and 40 g/L.3.3 Influences of complex agent3.2 Infuences of reductantComplex agent A is an alcohol acid containing lessExperiments show that the reductant (NaH2PO2)than 8 carbon atoms, it acts as the complex function.concentration, which increases from 10 g/L to 50 g/L,Complex agent B is an organic compound containingcoordinating N and S atoms, it acts as the stablehas lttle influence on the deposition rate, whichfunction. The effect of complex agent A and B onmaintains 0.4 pum/min, when the buffer agentelectroless plating rate and composition of Cu-Sn-Zn(CH3COONa) concentration is less than 15 g/L. Thealloy is shown in Fig.3.Cu-Sn-Zn alloy layer is not smooth and compact, andeasily shells out, because the pH value of the bath,80[(a)+0.8especially the pH value of interface betweendeposition substrate and solution, is not stable, due to-0.7the reaction: H2PO号 +H2O H2PO5 +OH +2eBut when the CH3COONa concentration is up to 25- Cu.- Deposition\ 10.6 司g/L, NaH2PO2 concentration increases from 10 g/L torate40 g/L, the deposition rate increases obviously.20 FHowever, when the NaHzPO2 concentration is over 40是g/L, the rate increases slowly. This is consistent with0.4the result of Ref. [9]. The effect of NaH2PO2 on the1203040S0rate and composition of Cu-Sn-Zn alloy is illustratedp(A)(g.L-4)in Fig.2. The content of Sn increases from 14.26% to60厂18.15%, that of Zn from 23.18% to 28.12%,and that0.9of Cu decreases from 62.56 % to 53.73%. The reasonmay be that Cut, Sn-* and Zn'“+ compete with each40-■一Deposition8里other to obtain electrons provided by reductant t另30-deposit. When the NaH2PO2 concentration is low, thenumber of electrons is fewer, but Cu*f is easier toobtain electrons to deposit, so Cu content is high,When NaH2PO2 concentration is high, the electron10fnumber is increased, the probability of Sn2+ and Zn20.6o0.05 0.100.15 0.20 0.25ρ(B)(g.L)60皆|:二 S●- ZnFig3 Influences of concentration of complex agent on告50F-Cu0.7deposition rate and composition of Cu-Sn-Zn alloy: (a) p(B)=*一Deposition rate0.15 g/L; (b)p(A)= 30 g/L40.6When the complex agent A concentration is low,0.5the deposition rate of Cu-Sn-Zn alloy increases rapidly20|with: the concentration isover中国煤化Iiowly, and whe theconcCNM H G the rate decreases.1(30 40 50The reason may be that Cul*, Sn'+ and Znt+ depositP(NaH2PO4)(g*L-1)through coordination ions. When the complex agent AFig.2 Influcences of concentration of NaH2PO2 on depositionconcentration is low, it is not enough to coordinate allrate and composition of Cu-Sn-Zn alloyCu2+, Sn2+ and Zn2*, so the deposition rate is slow, and226HE Xin-kuai, et alTrans. Nonferrous Met. Soc. China 16(2006) 223-228is increased with the increasing concentration ofcomplex agent A. After the rate reaches the maximum,the deposition rate will drop down, due to the greatresidual adsorption of complex agent A on thereduction surface and preventing the coordination ionsfrom depositing. Complex agent A also has greatinfluence on the composition of Cu-Sn-Zn alloy(Fig.3()). When it is relatively low, the Sn and Zncontents increase with the increasing of complex agentA,while Cu content rapidly reduces. When thecomplex agent A is over 30 g/L, Sn content increasesslowly, while Zn reduces. The reason may be that theamount of adsorption on the auto-catalytic reduction20 KV10umKYKY- 2800surface[16] is less when the complex agent A6)concentration is low, which accelerates the rate ofdeposition and crystallization. When the complexagent A concentration is high, the great amount ofadsorption will poison the reduction reaction[15].From the above discussion, the optimum concentrationof complex agent A is determined to be 30 g/L.As shown in Fig.3(b), the deposition rate dropsrapidly with the increasing of complex agent Fconcentration, while the Zn content almost sustainsunchangeable. When the complex agent E10um KYKY-2800 0-concentration is relatively low, the Sn contentincreases with the increasing of complex agent E(C)concentration, while that of Cu reduces. When thecomplex agent B concentration is over 0.1 g/L, thecomposition of Cu-Sn-Zn alloy maintains stable. Thecomplex agent B is probable to decrease the rate ofanti-reduction reaction, and strengthen cathodicpolarization, which leads to the formation of fine-grain,better evenness and compactness of the platinglayer(Fig.4). Considering the quality of Cu-Sn-Znalloyand the deposition rate, the optimum20KV10um KYKY 28000*concentration of complex agent B is 0.15 g/L.Fig.4 SEM morphologies of Cu-Sn-Zn alloys: () Optimum3.4 SEM morphology of different Cu-Sn-Zn platingplating layer; (b) Plating without complex agent A; (c) Platingallywithout complex agent BFig.4 shows the morphologies of different Cu-Sn-Zn alloy layers obtained from different electrolessplating layer. In the process of electroless plating,bath.complex agent A can alter the crystal microstructure inIt can be found that the morphology changesdeposition. The reason may be that complex agent A isremarkably. For the optimum samples, the besadsorbed on the auto catalytic reduction surface,evenness and compactness can be observed and needlewhich not only accelerates the deposition andholes hardly appear on its surface from SEM imagescrystallization rate to obtain fine-grain, but als(Fig.4(a)). For the samples without complex agent A,postpones or prevents the bath decomposing andalthough the compactness is good, but fine projectiondecreases hydrogen evolution to strengthen its stability,appears on its surface (Fig.4(b)). For the samples中国煤化iygen bitenesse Whilewithout complex agent B, not only a large number ofrate of anti-reductionneedle holes appear on microstructure surface, but alsoea |YHC N M H Gic polarization, whichthe evenness and compactness get worse as shown inleads to the formation of fine-grain, better evennessFig.4(c). Fig.4 shows that both complex agents A andand compactness of the plating layer. The air exposureB can improve the evenness and compactness ofexperiments shows that samples(a) do not fade after aHE Xin-kuai, et al/Trans. Nonferrous Met. Soc. China 16(2006) 223-228227year, samples(b) change from platinum to gray after 8is approximately 10.06 pum. Fig.7 shows the corrosionmonths, and samples(C) change from platinum to graycurves of different Cu-Sn- Zn plating alloys.and dark spots appear on its suface in 30 d. Thisilustrates that complex agents A and B can strengthen十(a)the stability to bear color changes of Cu-Sn-Zn platinglayer.-1.53.5 EDS and XRD analyses of Cu-Sn-Zn plating-3.0alloy layerFig.5 and Fig.6 show the EDS and XRD spectra-4.5-of Cu-Sn-Zn plating layer under optimum conditions.As shown in Fig.5, the main compositions are Cu, Sn,and Zn, and their atomic ratio is approximately 60 :30: 10. It shows that Cu2+, Sn2+ and Zn2+ obtain-7.5-0.5-0.4-0.3-0.2-0.1 0 0.1 0.2electrons and deposit on brass substrate with the helpPotential/Vof reductant(NaH2PO2). The XRD patterm (Fig.6)shows that the layer is a Cuo.6oSno.1oZn0.30 temaryalloy. .2(0);uSrg -6-ZnV-82610--0.5-0.4-0.3-0.2-0.100.10.20.3MC: 102Awol 20.00 (keV) Le: 68 (8)Tangt: 10.29 (egree-3-(c)E絮ETFig.5 EDS spectra of Cu-Sn-Zn aloy layer! -5●一Cuo.60Sno.1oZn0.30鱼-6-三-7-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1Fig.7 Corrosion curves of Cu Sn-Zn alys:; (@) 1 molL H2SO4ljj_jsolution; (b) 3.5% NaCl solution; (C) 10% NaOH solution; A,Optimum plaing layer(Cus4.46Snu7 sZ272 9); B, Plating without080100 .complex agent AC(3s_.6Sn.0zq17.z)x. C Plating without20/(°)complex agent B(Cu62 Sn6 ozZn31.2s); D, Brass substrateFig.6 XRD spectra of Cu-Sn-Zn alloy layers中国煤化工orosion potential of3.6 Electrochemical analyses test and thicknessplmV higher than thatmeasurement of plating alloy layerofbMYHC N M H Gon current density isThe thickness of Cu-Sn-Zn plating alloy layerthe lowest in 1mol/L H2SO4 solution, which improvesobtained under optimum conditions was measured bythe corrosionresistance of the layer remarkably, whilethe formula: d=(m2- m)/SXp, its average thicknessthe corrosion potential of layer C is unchangeable and228HE Xin-kuai, et alTrans. Nonferrous Met. Soc. China 16(2006) 223-228its corrosion current density is higher than that ofevenness and compactness and decrease needle holes,brass substrate, so its corrosion-resistance is the worsttherefore the properties of plating layer such as the(Fig.7(a)). Although the corrosion potential of layer Astability to bear color changes and corrosion resistanceis a bit more negative than that of layer B and brassare improved remarkably.substrate, its corrosion current density is the lowest,layer B is the second, and layer C is the highest inReferences3.5% NaCl neutral solution, which proves that thecorrosion-resistance and color-change resistance ofproperties[J]. Materials Protcction, 1995, 28(5): 7- -9.(in Chinese)layer A are the best in the neutral environment(in the[2] CAl Ji-Qing. Electroless Sn and Sn-Pb alloly platingU]. Corrosionair) and the layer C is easy to fade(Fig.7(b)). Theand Protection, 2001, 22(6): 270- 271.(in chinese)corrosion potential of layers A, B and C are[3] LIANG Cheng-bao, CHEN Bangyi CHEN Wan, WANG Hua.respectively about 300 mV, 100 mV and 50 mV higherElectrochemical hehavior of Cu-Zn-AI shape memory alloy afterthan that of brass substrate in 10% NaOH solution,surface mification by cletroless plated Ni-PD]. Rare Metals, 2004,and the corrosion current density of layer A is the23(4): 317-321.in Chinese)lowest, so the best anticorrosive layer in the alkali[4WANG Sen-lin, WU Hui-huang. Elctroless plating of Ni-Zn(Fe)-Palloy on carbon steel sheets[J]. Trans Nonferous Met Soc China,environment is layer A, the second is layer B, the2004, 14S2); 157- 161.worst is layer C(Fig.7(c)). Besides the evenness,[5] DENG Fu-ming, CHEN Xiao -hua, CHEN Wei-xiang. LI Wen-zhu.compactness and lest needle holes on the surface, theElectroless plating Ni-P matrix composite coating reinforced bymain reason for the best corrosion-resistance of layercarbon nanotubes[]. Trans Noferous Met Soc China, 2004, 144):A is that the highest contents of Sn and Zn in the681-685.Cu-Sn-Zn alloy which reach 45.54%. Although the[6] WANG Tian-xu, HU Yong-jun, MENG Jji long. Novel tehnology ofelectroless Nj-W-P on plastics and its interface behavior[J]. Transcontents of Sn and Zn in layer B and C areNoferous Met Soc China, 2004, 14

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