CN85101035A - Two-step electrochemical etching method of high voltage aluminium anode foil - Google Patents

Abstract

Use the aluminium dielectric capacitance device anode foils of the high cubic structure of two-stage process etching, by containing in the electrolyte of 3% hydrochloric acid and 1% with the aluminium of aluminum chloride form one, under the direct current effect of high current density, handle this paper tinsel for 75 ℃ in temperature, and in second step in a similar electrolyte, with much lower current density with at 80 ℃-82.5 ℃ of the temperature time said etched paper tinsels of processing.Etched like this paper tinsel has much higher electric capacity and the complete rectilinear channel structure that is produced by higher gully density.

Description

Two-step electrochemical etching method of high voltage aluminium anode foil

The present invention is about in containing first etching solution of hydrochloric acid and aluminum chloride, use the direct current of high current density and use similar etching solution and lower current density with second step thereupon, the aluminum electrolysis capacitor anode foil of the high cubic texture of etching is with the preparation high blocking more much higher than prior art electric capacity.

The explanation of prior art

Be used for the typical method of dielectric capacitance device aluminium foil in etching, in the first step, used a kind of sodium-chlor or other salt and vitriol based dielectric of containing.A kind of like this pH value of solution is neutral typically.This often will use nitric acid treatment subsequently.Yet the ratio electric capacity of resulting paper tinsel does not reach the high value that the present invention reaches.The typical electric capacity of prior art when 260 volts of scopes.The voltage product value reach 200 volts-microfarad/centimetre ², and the present invention up to 368 volts-microfarad/centimetre ²

United States Patent (USP) NO4213835 discloses a kind of can the manufacturing and has had only pure cylindrical or cube etch channels structure and gully density greater than 10

/ centimetre ²The method of electricity Jie etched heavy crystallization aluminium foil (high cube degree paper tinsel).This method is used the constant voltage etching technique.The problem of this technology is that itself can not the mass production etched foil.

United States Patent (USP) NO4420367 discloses a kind of by realization electrolysis channel-etch technology in first etch phase commonly used in technology, the method for etching electrolytic condenser recrystallization aluminium foil.It is electrolytic that the improvement of this patent is to enlarge the continuous etching right and wrong of raceway groove, the measure of finishing with chemical process in one or several etch phase.In the fs, make recrystallization aluminium foil or electrolysis raceway groove structure in aluminium, to form a channel structure, in subordinate phase, make the aluminium foil that obtains from first etch phase be subjected to once further non-electrolytically etching at least to realize the increase of raceway groove with channel structure by chemical milling.

For making aluminium foil, also used additive method than height ratio electric capacity.The object of the invention is to reach the ratio electric capacity of the high blocking of significant raising.

The invention describes aluminum capacitor anode foils that etching has a high cubic structure characteristic with more uniform etched foil of preparation and much higher electric capacity.

Some factor be for the ratio electric capacity that improves the aluminium electrolutic capacitor paper tinsel necessary.A factor is effectively to improve gully density and channel structure.Basically linearly extended raceway groove provides the surface-area that is produced by etching in a large number.When gully density increases, can cause that surface-area enlarges accordingly.Another factor of control ratio electric capacity is used aluminium foil type.People are known, are suitable for the sun level paper tinsel etch channels of high-voltage applications, mainly are in 100 directions.Thereby imagination has the paper tinsel of 100 higher crystalline orientations, and it is rational that the paper tinsel that promptly has a higher cubic texture can cause higher gully density.Be used for etched aluminium foil so far, have irregular cubic texture.Less than the paper tinsel of 25% cubic texture, such paper tinsel can be called " non-cube ".When the degree of cubic texture surpassed 50%, aluminium foil was divided into high cubic texture.In the present invention, have basically a kind of aluminium foil greater than 50% cubic texture and since when etching, obtain all even increases channel structure and thereby can increase gully density, so be better than hanging down the paper tinsel of cube degree.Another important factor that control improves than electric capacity is the engraving method of the generation of control raceway groove and the etch channels degree of depth and width.Combination as shown in table 1, that etched aluminium foil and engraving method are suitably selected causes more uniform channel structure and much higher electric capacity.

Table 1

Capacitance voltage (CV) volt-microfarad during 260 volts of foil-type Method types/centimetre ²

Standard normal 200

Non-cube

Master copy invention 210

Non-cube

New height cube routine 210

New square the present invention 368 in height side

Electrolytical chemical constitution of the first step etching of the present invention and character are that the control high pressure is for example greater than a principal element of 200 volts of direct current etching anode foils etching characteristics.Hydrochloric acid is because it has avoided blocking the aluminum hydroxide precipitation of the raceway groove of the abundant extension that the inventive method enlarges, so use is better than other muriates in the method.If allow such precipitation to produce, it will influence the height cube character of paper tinsel, and can not make full use of suitable for resulting benefit by high cubic texture and engraving method.This point is shown in the third line of table 1, and it has pointed out to use with conventional engraving method the result of high cubic texture paper tinsel, obtains much lower electric capacity.Thereby the temperature of the first step remain on or be lower than 85 ℃ so that vaporization losses minimize make method economy many and be easier to control.

In the first step, paper tinsel is containing 1.5 to 7% hydrochloric acid and 0 to 0%(with the aluminum chloride form) electrolytic solution in etching under the direct current effect under 70 ° to 85 ℃.Current density range from 0.25 to 0.6 peace/centimetre ²Etching charge is 6 to 25 coulombs/centimetre ²

In second step, paper tinsel is containing 1.5 to 7% hydrochloric acid, in 75 to 90 ℃ of processing in the similar electrolytic solution of the aluminium of 0 to 2% aluminum chloride form.Resulting paper tinsel, for the paper tinsel that forms 260 volts the time in the mass production, have up to 368 volts-microfarad/centimetre ²Electric capacity.Voltage range.Laboratory test shows that higher value is possible.

Methods and results of the present invention forms that a kind of output is equivalent to or is much higher than can the industrial paper tinsel of getable the best and do not need to change in a large number the very effective and economic two step etching method of existing production machinery.The invention has the advantages that and obtain having greater than 10

/ centimetre ²Etch channels structure and this etch channels of the gully density on paper tinsel surface are evenly distributed on the paper tinsel.By means of method of the present invention, in the paper tinsel intensity of remaining valid, having obtained having minimum possibility aluminium corrosive the highest possibility surface increase and electric capacity increases.

Fig. 1 is with the stereoscan photograph of the etched a slice aluminum electrolysis capacitor anode of traditional method cross section, has shown the channel structure that obtains thus.

Fig. 2 a and 2b are the stereoscan photographs according to the etched a slice aluminum electrolysis capacitor anode of the inventive method cross section, have shown the channel structure of the relative linear extension that obtains thus.Fig. 2 a takes later in the first step of the inventive method.Fig. 2 b took after second step of this method, had shown complete etched paper tinsel.

As preferential selection embodiment, has high cubic texture, preferably surpass 70%, and thickness is that 70 to 100 microns aluminum electrolysis capacitor anode foil is in the first step, contain 3% hydrochloric acid and 1% etching electrolytic solution with one, obtain etching under the direct current effect, handling this paper tinsel under 75 ℃ with the aluminium of chloride form.Current density be 0.31 to 0.45 the peace/centimetre ², the etching electric weight be the 9-15 coulomb/centimetre ²In second step of preferred method, this etched paper tinsel contains in the electrolytic solution of similar solution one, i.e. 3% hydrochloric acid, and 1% aluminium with the aluminum chloride form, this solution remains between 75 ° to 85 ℃, under the direct current effect, handles.Current density be 0.10 to 0.15 the peace/centimetre ², etching charge is 40 to 50 coulombs/centimetre ²The purpose of this solution is to increase the raceway groove that generates in the first step.

In order to take three strict factors into account, the physical strength of paper tinsel, high capacitance and production cost have been determined the top condition of present method, use following value.In the first step, current density remain on 0.4 the peace/centimetre ², the etching coulomb is 13-14.Temperature remains on 75 ℃.Second the step in, temperature remains between 80 ° and 82.5 ℃, etching charge be the 40-50 coulomb/centimetre ²The optimal capacitance that obtains by this method.Magnitude of voltage, 260 volts of paper tinsels that generate be 355 volts-microfarad/centimetre ², 465 volts of paper tinsels that generate be 321 volts-microfarad/centimetre ²This two-stage process has obtained a kind of as Fig. 2 a that takes later in the first step and the etch channels structure that the stereoscan photograph of the 2b of shooting shows after second step.

By using higher current density, a large amount of etch channels generate in the first step.In second step,, make these raceway grooves become wideer and do not produce new raceway groove by using lower current density and higher temperature.

Figure has shown the channel structure of etched foil cross section.The bright gray structure of linearity is the etch channels of paper tinsel, and the border surface of paper tinsel indistinctly can be distinguished in the above and below of the raceway groove that faces toward seating plane.The prior art of contrast as graphic extension in Fig. 1 presents on the vertical plane of Fig. 2 a and 2b stereoscan photograph, and rectilinear relatively, the channel structure of extension is clearly.Grayish channel region further runs through and passes through paper tinsel.They more or less are pattern clocklike, and the density of channel structure is significantly greater than the density of prior art shown in Fig. 1.Crucial meaning on the photo is that many raceway grooves mutually disjoint, thereby makes the paper tinsel and the isolating fact of channel structure.

In the method for the invention, use to have as described above greater than 70% cubical high cubic texture paper tinsel, with milligram/centimetre ²Meter dissolved aluminium amount is approximately 5.0-9.0.Under express when when 260 volts and 465 volts generate anodic oxides the electric capacity of paper tinsel.The CV number is a capacitance voltage, and CV/ milligram number is capacitance voltage/every square centimeter of dissolved aluminium amount.This numeral is the linear module to the engraving method relative efficiency.

The table II

260 volts 465 volts in dissolved aluminium

Milligram/centimetre ²CV CV/ milligram CV CV/ milligram

7.3 274 37 235 32

8.3 310 37 285 34

9.3 368 39 328 35

In parameter of the present invention, following variation allows.Used aluminium foil is a kind of paper tinsel with very high cubic texture, and this is meant that this paper tinsel has high grain orientation in 100 directions.Concerning method of the present invention, have been found that having at least 70% a kind of paper tinsel at the crystal grain of 100 directions orientations is enough to reach desirable result.Such paper tinsel commercial can be from Showa aluminium company, Teye aluminium company and Seal, a branch of Peahiney aluminium company obtains.The paper tinsel of high cube degree can be realized the complete rectilinear raceway groove of etching in the surface-area that keeps etching to produce.The generation of raceway groove trends towards more even, and gully density can increase then.Cube degree of paper tinsel is higher, than the electric capacity height of will healing.Yet, for the production purpose, determine according to experiment, 70% or high slightly cube degree just enough.

The variation range of other parameter values of the present invention also is possible.Chemical constitution in the first step dielectric medium and character are intended to obtain a kind of acidic medium that has a large amount of muriates to exist.The preferential aluminum hydroxide precipitation of hydrochloric acid of selecting to avoid to take place with sodium-chlor the time.Adding aluminium makes that electrolytic solution is cheap and makes in the etching process electrolytical replacing reduce to bottom line.The parameter area of the first step electrolyte is as follows.Hydrochloric acid can exist with from 1.5 to 7% concentration ranges, can exist with 0% to 2% scope with the aluminium of aluminum chloride form.The temperature range of the first step can from 70 to 85 ℃.Current density can from 0.25 to 0.60 peace/centimetre ²Change in the scope.Etching charge can from 6 to 25 coulombs/centimetre ²Change in the scope.For the high blocking of mass production, these scopes have been determined according to experiment.The scope width that is provided enables high-speed mass production paper tinsel and is not the complicated Controlling System of these parameters of monitoring, thereby makes the equipment of the inventive method relatively cheap.With regard to temperature range, surpass 85 ℃ and flash to and be important factor.If temperature is lower than 70 ℃, or engraving method can not carry out, or working efficiency reduces aspect the number that generates desired etch channels.With regard to current density, the lower-most point that density is lower than this scope will cause lower raceway groove to generate, thus lower gully density.If current density is higher than described scope, then the big young pathbreaker of raceway groove is owing to the competition between raceway groove intensification that has generated and the new raceway groove generation is tending towards inhomogeneous.As in any engraving method, because when under high pressure forming anode foils with a kind of oxide compound, in fact many raceway grooves will seal, so will avoid uneven raceway groove.

The scope of the value in second step is as follows in the method.In the electrolyte in second step, hydrochloric acid can be from 1.5% to 7% range changing, can be from 0 to 2% range changing with the aluminium of chloride form.Temperature range can be by 75 to 90 ℃, current density can from 0.10 to 0.15 the peace/centimetre ²Range changing and etching electric weight can be from 30 to 70 coulombs of range changings.

The curve map that provides among Fig. 3 shows current density to the impact of the electric capacity of formation paper tinsel.

According to present embodiment, obviously can be used for high-voltage electrolysis capacitor according to the etched paper tinsel of the present invention and obtain than the much higher ratio electric capacity that made in the past/centimetre² Therefore, for obtaining given electric capacity, the capacitor that this capacitor can have littler volume or equal volume can have higher electricity Hold. Although those skilled in the art may propose various less important improvement, and are self-evident, I wish those rationally and are suitably entered improvement in the claims scope at this, summarize to enter among the scope of patent protection.

Errata

Claims (12)

1, a kind of two-stage process of etching dielectric capacitance device, wherein this paper tinsel have greater than 70% cubical high cubic texture, and this method comprises the first step:

Contain between 1.5% and 7% hydrochloric acid and 0% to 2% aluminium one, under the direct current effect, handle said paper tinsel between 70 ℃ and 85 ℃ of the temperature with chloride form; With

Immerse in the said hydrochloric acid electrolyte and have current density at said paper tinsel at 0.25 and 0.60 ampere/centimetre ²Between the time, make 6 to 25 Coulombian charges by said paper tinsel; With

In second step, an electrolyte of forming with the aluminium of aluminum chloride form between by from 1.5 to 7% hydrochloric acid and 0 to 2%, in current density be 0.10 to 0.15 pacify/centimetre ³The direct current effect under, in 75 ° to 90 ℃ of temperature, handle by the said paper tinsel of discharging in said first electrolyte with 40 to 50 etching coulombs.

2, according to the process of claim 1 wherein that said aluminium foil has 70% or higher cube degree.

3, be 3% according to the hydrochloric acid percentage ratio in the electrolyte that the process of claim 1 wherein in the said the first step.

4, according to the process of claim 1 wherein that in the electrolyte of the said the first step percentage ratio with the aluminium of chloride form is 1%.

5, according to the process of claim 1 wherein that the temperature of the said the first step is 75 ℃.

6, according to the process of claim 1 wherein the current density of the said the first step be 0.40 peace/centimetre ²

7, according to the process of claim 1 wherein the etching coulomb be the 13-14 coulomb/centimetre ²

8, the process of claim 1 wherein that said electrolyte contains 3% hydrochloric acid in said second step.

9, the process of claim 1 wherein that said electrolyte contains 1% aluminium with the aluminum chloride form in said second step.

10, the process of claim 1 wherein that the temperature of said the first step electrolyte is 80 °-82.5 ℃.

11, the process of claim 1 wherein said second the step in current density be 0.12 the peace/centimetre ²

12, the process of claim 1 wherein that the etching coulomb in said second step is 40-50.

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