A kind of activating process of nonmetal basal body chemical plating
Technical field
The present invention relates to a kind of new colloidal palladium activating technology, be used for nonmetal basal body chemical plating, to obtain even metal coating.
Background technology
Electroless plating is electroless plating (Electroless-plating), autocatalytic plating (auto-catalytic plating) again, and its principle is by chemical reaction reducing metal salt and makes metal deposition that the matrix surface of catalytic activity arranged.The metallic surface generally all is coated with catalytic activity to chemistry, and nonmetallic surface then need pass through activation treatment, promptly deposits some metal particles in advance as catalyzer on its surface.In the electroless plating process, the metal that reaction generates at first is deposited on the metal particle catalyzer, and the metal that reaction generates can continue this chemical reaction of catalysis, thus realize the growth of metal level, in flakes, thicken, finally form the successive metallic membrane.
The activation effect of non-metal base surface has direct influence to the quality of chemical plating.In theory, everyly can be used for activating matrix in the technology of matrix surface uniform deposition metal particle, still, good activating process should make the metal particle particle diameter of generation little, be evenly distributed, strong adhesion.Introduced the various activating process of electroless plating in many papers and the patent, existing people sums up this.For example, Jiang Xiaoxia etc. [Jiang Xiaoxia, Shen Wei. the theoretical and practice of electroless plating. Beijing National Defense Industry Press, 2000,336-339] activation method is summarized as the palladium method of soaking, catalytic coating method, silver-colored slurry method, molybdenum manganese method etc.; Liu Jianguo etc. [Liu Jianguo, Chen Chunhua, Zheng family's Son. matrix surface Studies on Activation Method in the chemical plating of non-metal material technology. sufacing, 2006,31 (3): 5-8] above method all is classified as conventional activation method, and sum up four class methods again, be vapour deposition process, dielectric layer electric discharge, photochemical method and autocatalytic method, but back four kinds of methods are of limited application or improve.In above-mentioned many activation methods, to soak the palladium method and be most widely used, its principle is with the palladium in solution reduction and make the palladium metal particulate be dispersed in matrix surface by chemical reaction.Except that palladium base activator, other metal matrix activator also has many report [L.P.Donovan, E.Maguire, L.A.Kadison.Aqueoussuspensions for surface activation of nonconductors for electroless plating.US Patent3958048,1976], but range of application is very limited.The model who soaks the palladium method is colloidal palladium method [Zhang Yongfeng, Ma Lingjun, Guo Weimin, Cui Zhaoxia, temperature is blue or green. the activating process of nonmetal chemistry plating. and developing material and application, 2000,15 (2): 30-34], early stage activating process is a two-step approach, promptly handles with sensitizing agent earlier and uses Treatment with activating agent again.Sensitizing agent and activator commonly used are Sn
2+And pd
2+Acidic solution, matrix surface produces and to contain Sn during sensitization
2+Colloid, obtain the particulate of palladium during activation by following reaction:
Sn
2++Pd
2+→Sn
4++Pd
Two step activation methods bother very much, 1961 American scholar Shipley[Shipley C.R.Method of electrolessdeposition on a substrate and catalyst therefore.US Patent:3011920,1961.] invented a step activation method, be about to sensitizing agent Sn
2+With activator Pd
2+Strongly acidic solution directly mix, form colloidal palladium, i.e. the peripheral parcel of the palladium metal nuclear Sn that generates by reduction reaction
2+With excessive Cl
-The electronegative colloid that forms.After the activation, the implanted palladium nuclear of matrix surface, but in water washing process, coat the tin ion hydrolysis of palladium nuclear, form Sn (OH)
4And Sn (OH)
2, the latter also can be oxidised with air to the former.Make palladium nuclear expose out, matrix surface must be handled through dispergation.
The colloidal palladium method is still the method that is most widely used so far, but it has many shortcomings, comprises stability, the acid corrosion of colloidal palladium, introducing of tin or the like.Based on these problems, ionic palladium type activation solution arises at the historic moment, it is can be at the homodisperse palladium solution that contains of matrix surface, mainly be palladium complex solution, complexing agent generally is organic group such as aminopyridine etc., complexing agent simultaneously can play the effect of dispersion agent, otherwise needs other addition polymerization compound composition as dispersion agent (as PVA).After matrix soaked overactivation liquid, because the effect of dispersion agent, matrix surface evenly adsorbed one deck liquid, uses reductive agent (as N then
2H
4, NaBH
4, [Wang Laijun such as aldehyde, alcohol; Civilization is fragrant; Li Yushan; Yang Dong; Song Chongli; Chen Jing. electroless plating activating process and use the chemical plating method of this metal depositing process. Chinese patent application numbers 200510086380.6, the applying date: on September 9th, 2005]) reduction, can form palladium metal nuclear at matrix surface.The advantage non-corrosiveness of ionic palladium activation solution has avoided in the colloidal palladium reactivation process matrix surface because of the absorption tin ion influences coating adhesion, no longer needs to separate simultaneously glue process.But the shortcoming of ionic palladium activation method is also clearly, and promptly the formed palladium of reduction reaction nuclear only is to float over matrix surface, a little less than the bonding force of matrix, and problem such as after electroless plating, coating can face peeling unavoidably, foam, come off.The ionic palladium activation method still needs further perfect.Except that colloidal palladium and ionic palladium method, can also find in the document many other soak palladium type activation method, [H.B.Zhao, K.Pflanz, J.H.Gu, et al.Preparation of palladiumcomposite membranes by modified electroless plating procedure.J.Membr.Sci..1998,142:147~157] [Li, A.; Xiong, G.; Gu, J.; Zheng, L.Preparation of Pd/ceramiccomposite membrane 1.Improvement of the conventional preparation technique.J.Membr.Sci.110 (1996), 257], because be of limited application, do not exemplify one by one at this, the problem that these methods exist mainly is a complex operation or wayward.
Summary of the invention
The objective of the invention is to the invention provides a kind of improved colloidal palladium technology in order to solve deficiencies such as the activation solution instability that exists in traditional colloidal palladium reactivation process, tin ion interference, complicated operation.
Technical scheme of the present invention is: the present invention adopts a kind of novel Pd (OH)
2The colloid activation solution does not almost have corrodibility to matrix, and strong with the bonding force of matrix, be difficult for peeling, foam, come off, very and the technology that helps electroless plating front activating step amplify.
Concrete technical scheme of the present invention is: a kind of activating process of nonmetal basal body chemical plating, after substrate pretreated, immerse palladium hydroxide colloid activation solution, take out dry, palladium hydroxide with matrix surface reduces then, make the particulate of matrix surface deposition layer of metal attitude palladium, can reach the activatory purpose.
Wherein the preparation concrete operations step of palladium hydroxide colloid activation solution is as follows:
To in an amount of palladium salt adding less water it is partly dissolved, because the hydrolysis of palladium, it is acid that solution is:
Under condition of stirring, drip alkaline solution, machinery, electromagnetism, ultrasonic agitation all can, make the abundant hydrolysis of palladium ion and form the palladium hydroxide colloid, up to the pH of system value stabilization till 5-6, obtain the soliquid of dark-brown or black, excessive if alkali lye adds, then usable acid solution neutralization.The preferred Palladous chloride of wherein said palladium salt, Palladous nitrate or palladous sulfate, preferred sodium hydroxide of alkali lye or potassium hydroxide solution, palladium content is 0.005-0.05mol/L in the colloid activation solution that finally obtains.
Matrix goes to toward carrying out alligatoring and cleaning in activation, and pretreated matrix immerses in the above-mentioned colloidal palladium liquid, waits a moment and takes out drying, dries, dries up or dry and all can.With the palladium hydroxide reduction of matrix surface, method of reducing can be divided into wet method and dry method at last.Wet method adopts the reductant solution reduction, is preferably diamine (N
2H
4) solution, concentration is 0.1-1M, and reduction temperature is 40-70 ℃, and the recovery time is 1-5min; Dry method adopts the reducing gas reduction, is preferably hydrogen reducing, and reduction temperature is 50-200 ℃, and the recovery time is 0.5-3h.
The drying employing that matrix soaks behind the palladium is dried, is dried up or dries.The electroless plating that the present invention especially is fit to transition metal such as palladium, nickel, silver, copper etc. activates in advance.
The present invention is particularly useful for porous matrix, also is applicable to dense substrate, as pottery, glass, plastics etc.Beneficial effect:
Compared with prior art, advantage of the present invention is: this activation method has the advantage of colloidal palladium activation method and ionic palladium activation method concurrently.Compare with the colloidal palladium activation method, the palladium activation solution of this patent is more stable, not stanniferous, almost non-corrosiveness; Compare with the ionic palladium activation method, do not introduce organic substance, thereby make that the metallic membrane for preparing is at high temperature more stable, non-scale.This patent practicality is wider, operates also more conveniently, is particularly useful for the activation of porous non-metallic matrix.
Figure of description
Fig. 1 .Pd (OH)
2The palladium film surface topography map of activation back preparation.
Fig. 2. with palladium film (5.9 microns) the resistance to air loss figure for preparing after the different methods activation.Wherein transverse axis is a normal atmosphere, and the longitudinal axis is N
2, reduces with traditional method, and zero uses wet reducing, and △ reduces with dry method.
Fig. 3 .SnCl
2/ PdCl
2Nickel film (6.5 microns) surface topography map of activation back preparation.
Fig. 4 .Pd (OH)
2Nickel film (6.4 microns) surface topography map of activation back preparation.
Fig. 5 .Pd (0H)
2The silverskin surface topography map of activation back preparation.
Embodiment
The technology of the present invention details is by following embodiment detailed description in addition.
Embodiment 1
(1). the preparation of activation solution: with 0.08gPdCl
2Be added in the aqueous solution of 10ml, shake up, regulate PdCl with the NaOH solution of 40ml 1M
2The pH value to 10 of solution, sonic oscillation 2 hours, PdCl in this journey
2After hydrolysis takes place, with the NaOH formation colloid that reacts, finally obtain the pH value and be 6 stable colloid, wherein palladium content is 0.005mol/L.
(2). activation: the porous ceramic matrices suitable after the clean dry is immersed in the above-mentioned colloid, treat that matrix becomes orange while color distribution and takes out relatively evenly the time, blow to the solution of carrier surface no longer mobilely with blower, be placed under the hydrogen atmosphere, 50 ℃ of reduction 3h become black until orange matrix.
(3). utilize the method palladium plated film of electroless plating.Palladium plating solution consists of: the PdCl of 5g/L
2, the strong aqua of 500ml/L, the disodium ethylene diamine tetraacetate of 70g/L, the N of 0.5M
2H
4, coating temperature is 30 ℃.
Compare the palladium film surface gloss good (as shown in Figure 1) of this method activation back preparation, defective few (shown in the △ curve of Fig. 2) with traditional method (as the curve of Fig. 2).
Embodiment 2
(1). the preparation of activation solution is with embodiment 1 (1).But the palladium source changes the Pd (NO of 0.5g into
3)
2, alkali lye is the KOH solution of 10ml2M, finally obtains the pH value and be 5 stable colloid, wherein palladium content is 0.05mol/L.
(2). activation: the sintered glass matrix after the clean dry is immersed Pd (OH)
2In the suspension liquid, become orange to the surface and color distribution is taken out relatively evenly the time, in 120 ℃ of dryings.After taking-up was cooled to room temperature, putting into temperature was 70 ℃, and concentration is the N of 0.1M
2H
4Reduce 5min in the solution, take out, water washes out the relatively poor material of surface adhesion force.
(3). chemical plating method prepares the palladium film with embodiment 1 (3).
The palladium film defective of this method activation back preparation is also than lack (shown in zero curve of Fig. 2) of traditional method.
Embodiment 3
(1). after with hydrofluoric acid the glass carrier of densification being corroded, cleaning-drying.
(2). the preparation of activation solution, the activation of matrix, and the method for chemical palladium-plating is with embodiment 1 (1), (2).But the palladium source changes the PdCl of 0.1g into during activation
2, alkali lye is 40ml 1M NaOH solution, palladium content is 0.007mol/L in the colloid.Use H
2During reduction, temperature is 200 ℃, and the time is 0.5h.
Embodiment 4
(1). the preparation of activation solution and the activation of porous ceramic matrices suitable are with embodiment 2 (1), (2).But the palladium source changes the PdSO of 0.2g into
4, alkali lye is 30ml 1M NaOH solution, palladium content is 0.01mol/L in the colloid.Use N
4H
4During reduction, temperature is 40 ℃, N
4H
4Concentration is 1M, and the time is 1min.
(2). prepare the nickel film with chemical plating method, it consists of the NiSO of 30g/L
46H
2O, the strong aqua coating temperature of 250ml/L is 60 ℃.
Because this activation method activation back has deposited a large amount of palladium crystal seeds at carrier surface, so speed of response is very fast when utilizing the chemical plating method plated film, just can meet the requirements of thickness in time of weak point, reduced nickel film oxidized possibility in preparation.Therefore with use SnCl
2/ PdCl
2The nickel film (as Fig. 2) of activation back preparation is compared, and the nickel film (as Fig. 3) for preparing with the present invention has better surface flatness, and glossiness might as well.
Embodiment 5
(1). the preparation of activation solution and the activation of porous ceramic matrices suitable are with embodiment 2 (1), (2).
(2). prepare silverskin with chemical plating method, it consists of: the AgNO of 5g/L
3, the disodium ethylene diamine tetraacetate of 35g/L, the strong aqua of 500ml/L, coating temperature are 30 ℃.Preparation-obtained silverskin as shown in Figure 4.