KR930000099B1 - Orifice plate structure - Google Patents

Abstract

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Description

Orifice plate structure

1A-1E are schematic cross-sectional views of the prior art for manufacturing a fluid jet orifice plate,

2A-2D are schematic cross-sectional views illustrating a method of manufacturing an orifice plate (eg, a fluid jet orifice plate and / or photoetching mask, etc.) according to the present invention.

* Explanation of symbols for main parts of the drawings

10: orifice plate 12, 56: substrate

11, 52: front 13, 54: back

14, 50: photoresist material 16: exposure mask

18: circular mask area 20,58: peg

22: crystalline nickel 24, 64: holes

26, 62: orifice 59: opening

60: nickel- or cobalt-phosphorus alloy

The present invention relates to a novel improved orifice plate structure, and more particularly to a novel improved orifice plate structure used in a fluid jet printing apparatus or used as a mask in a photo-etching method.

As used herein and in the claims, the term “orifice plate” refers to any substrate member having orifices, holes, openings, or pattern areas of various sizes and geometries. Therefore, the following description only refers to the application of the present invention to a special field, for example, a fluid jet orifice plate structure and a photo-etching mask structure, but the application in this field merely shows a preferred embodiment of the present invention. It is not limited to this.

Currently, a wide range of printing devices using the fluid jet method are used. Typically, in the device according to the prior art, the fluid jet orifices formed in the orifice plate are arranged in a linear manner, causing a problem in the filament of the pressure indicating fluid (eg, ink, dye, etc.) from the orifice plate. Independently adjustable electrostatic electrodes are placed downward to fit each orifice along the so-called “drop-forming” region. According to the known principle of electrostatic induction, fluid filaments cause a potential opposite to the polarity and are related to the amount of potential of each charged electrode thereof. When a fluid droplet separates from the filament, the induced electrostatic charge is trapped in this droplet.

In the conventional method, a fluid jet orifice plate was manufactured using standard methods used to manufacture semiconductors and the like in the semiconductor industry (see Maissel et al, Handbook of thin Film Technology, McGraw-Hill, Inc, Chapter 7 (1970)). .

The conventional method of manufacturing the fluid jet orifice plate 10 is as shown in FIGS. 1A-1E. The substrate 12 of copper or copper alloy is coated on the front and back surfaces 11 and 13 with a suitable photoresist material 14 and covered with an exposure mask 16, respectively. This structure is then exposed to light to reveal a region adjacent to the area 18 that will be circularly masked and will define the orifice location. Removal of photoresist material exposed to light from the substrate using a suitable chemical cleaner leaves unexposed peg 20, which fits into area 18 of mask 16. . The back side 13 of the substrate 12 is treated in a similar manner so that the large diameter peg 20 remains and fits into the small diameter peg 20 on the front surface 11.

Both sides of the substrate are electroplated with crystalline nickel 22, which is deposited on the substrate and does not deposit on the peg as it cleans the exposed photoresist on this area. It is desirable to dissolve the pegs present on each side of the substrate and to etch each side so that the lower copper substrate can form a hole 24 through the nickel coating that defines the orifice 26 and the engine connecting the front and back surfaces. Do.

Since the inks used in typical ink jet apparatuses become colourful in paper printing, these ink formulations are chosen to have affinity (when possible) without corrosion of the electroform crystalline nickel and typical copper or copper alloy substrate modes. However, in recent years, the fluid jet technology has been expanded and applied to the textile industry. (Refer to the pending US patent application No. 231,326 (filed Feb. 4, 1981) and 393,698 (June 30, 1982) One application)]. For applications in the textile industry, the fluids and the conditions required for the fabrics to be treated by the fluids should be compatible. However, sometimes they are typically used in the textile industry and fluids corrode (more or less in paper printing) crystalline nickel plated on copper or copper alloy orifice substrates and / or substrates. Many of the fluids typically used in the textile industry are corrosive fluids and one skilled in the art will appreciate that all fluid jet orifice plates and fluids in contact with the following materials must have affinity.

Hydrobromic acid glycolic acid

Hydrogen Iodide Citric Acid

Boric acid tartaric acid

Hypophosphoric acid trifluoro acetic acid

Orthophosphoric acid

Sulfonic acid ascorbic acid

Trichloro Acetate Lithium Hydroxide

Benzenesulfonic Acid Hydrazine

Trisodium salt of toluene sulfonic acid ethylene

Picric acid diaminetetra acetic acid

Malonic acid sodium cyanide

Therefore, conventional orifice plates are often inadequate, and there is a need for orifice plates that are chemically stable in the presence of a wide range of chemicals commonly encountered in the textile industry. Until the present invention such orifice plates were not manufactured.

The present invention specifically provides an orifice plate with an improved structure, which makes it possible to suitably use corrosive fluids in fluid jet devices in the textile industry. According to the invention this advantageous property is obtained by fusing an amorphous nickel- or -cobalt-phosphorus alloy onto a highly corrosion resistant substrate.

Several important accessories for use in relatively thin devices are typically manufactured by photofabrication methods. One such accessory is a fluid jet orifice plate used in a fluid jet printing apparatus as described above. In the photofabrication method, the substrate to be photofabricated is coated with a thin photosensitive material, so-called “photoresist,” which is exposed to light, typically blue or ultraviolet light, to form an exposure pattern thereon. The photoresist is decomposed to dissolve or crosslinked molecules in the photoresist to be selectively insoluble. In either case, after exposure and development (to selectively remove soluble photoresist), foreign matter in the form of a thin film in a preselected pattern is present on the substrate to be photofabricated. The selective coating may then be used to plate the exposed substrate portion and remove the photoresist, or the substrate may proceed directly to the next step without such an intermediate plating step.

In the next step, the substrate is treated with a caustic that selectively erodes the substrate material. In either case, the photoresist or overplating should not be eroded by the caustic. Once a suitable corrosive agent is found, the substrate to be etched is subjected to metal dissolution treatment in the areas where the metal is exposed so that the remaining metal is covered with a protective material in the form of photoresist or over plating (see FIGS. 1A-1E).

Most photoresist materials are plastic coatings that are thin enough to etch and undercut them, so they tend to break out of the substrate and intermittently break off, resulting in jagged or irregular edges.

Electroplated masks that protect the substrate during etching as described above are typically metallic materials, although these masks are rigid and resistant to release, but must be resistant to corrosive agents so that they can mask. . In the case of materials such as stainless steel, titanium, zirconium, hafnium, tungsten, molybdenum, model metals or Hastelloy, it is very difficult to find masking materials that are selectively etched by known caustic agents. Thus, in accordance with another aspect of the present invention, new and unexpected methods of defending the photoetching agent using alloys have been obtained, allowing the selective etching of many materials that were previously known to be difficult to etch. Therefore, the present invention can be used particularly suitably for a photoetching mask having a desired exposure pattern.

The substrate advantageously used according to the invention can be any material which has a high degree of corrosion resistance and which is stable during continuous contact with the aqueous solution for a long time. Suitable substrates include, for example, monel metals (eg copper-nickel alloys), ferritic stainless steels (eg low stainless steels), titanium, zirconium and martensitic stainless steels. Of these suitable substrate materials, stainless steel is preferred because it is relatively easy to etch (e.g., removal of the substrate after plating results in openings in communication with the orifices). Similarly, the monel metal can be preferably etched by ferric chloride, since the advantage of shortening the etching time is also obtained.

As used herein, "preferred" etching or "selective" etching means that the substrate material can be etched without affecting the plated amorphous alloy layer.

Zirconium and titanium can be preferably etched using hydrofluoric acid acidified with hydrochloric acid. Attaching the amorphous nickel- or cobalt-phosphorus alloy to titanium may preferably be performed by etching its surface with hydrochloric acid solution mixed with ethylene glycol and then striking this surface using copper cyanide strike. “Glass phase” amorphous nickel- or cobalt-phosphorus alloys can be firmly attached to copper strikes. Zirconium can also be prepared initially by plating its surface in a Watt Nickel bath, which is pretreated by immersion in hydrofluoric acid and acid baths. Thus, amorphous nickel can be more easily attached to what is nickel plating. Those skilled in the art will appreciate that other various surface preparation methods and techniques may be advantageously utilized.

US Pat. No. 4,108,739 by Dodo Blast Furnace, 3,041,254 by Peppler, 3,041,255 by Fassal, 2,06 9,566 by Turtle, 3,303,111 by Pitch, Heinz et al. No. 3,475,293, No. 3,658,569 by Philip, No. 3,759,803 by Two Rose, etc., No. 4,08 6,149 by Martinsons, No. 4,113,248 by Yanagioka, No. 4,127,709 by Ruben and No. by Takahashi 4,224,133.

The present invention relates in particular to useful structures which render the useful properties of amorphous nickel- or cobalt-phosphorus alloys resistant to corrosive fluids by depositing them on at least one surface of a highly corrosion resistant substrate forming an orifice plate.

The amorphous nickel-phosphorus alloy according to the present invention can be deposited by a chemical reduction method or an electroless solution method. See A. Kenneth Graham, Electroplating Engineering Handbook, 3rd Ed, Van Nostrand Reinhold Co., New York, N Y. , Pages 486-507 (1971). Although the phosphorus content in this deposition ranges from 12 to 13 atomic percent, the upper limit level of phosphorus contained in the plating can formally yield up to 20 atomic percent, resulting in the highest corrosion resistance. This type, although expensive plating method, is rather similar to the electrolytic plating amorphous nickel-phosphorus alloy, which is described in more detail below.

Generally, amorphous materials have been electroplated in the past. In particular, plating of amorphous nickel or cobalt-phosphorus alloys has already been carried out. See A. Brenner, Electro-deposition of Alloys, Vol. II, Academic Press, New York, N.Y. Chapter 35 (1963)]. It has been found that the plating of such amorphous nickel or cobalt-phosphorus alloys exhibits significantly improved corrosion resistance properties compared to crystalline nickel plating or crystalline cobalt plating, for example, which is particularly useful for the manufacture of fluid jet orifice plates. It is early.

Particularly preferred nickel- or cobalt-phosphorus alloys can be prepared by the present invention with high stability, which have high corrosion resistance when the phosphorus content is about 20 atomic percent with respect to nickel or about 12 atomic percent with respect to cobalt. do. Various electroplating baths suitable for plating amorphous nickel- or cobalt-phosphorus alloys will be described in more detail with reference to the following examples.

Preferred embodiments of the process according to the invention are shown graphically in figures 2a to 2d. In the figure, a photosensitive photoresist material 50 is applied onto each of the front and back surfaces 52 and 54 of the substrate 56. A suitable light masking technique is then applied that utilizes light rays that expose the photoresist material 50 to light to cause the unexposed photoresist peg 58 to remain on the post-exposure front surface 52 and is oxidized and removed. The material remains with an opening 59 defined by the photoresist material 50 on the back 54 of the engine 56. Thus, the entire back surface 54 of the substrate 56 is covered by a suitable plating means (not shown), i.e. by a plating tape or the like, and the front side is plated by a nickel- or cobalt-phosphorous alloy 60. This preforms the orifice 62 here. After preforming, the orifice 62 removes the plating prevention means to expose the opening 59 in the photoresist material 50 on the back 54 of the substrate 56.

Thus heated iron chloride or other suitable etching compound is sprayed into the opening 59 to dissolve the metal substrate 56 directly below the opening. At this time, etching is not performed at the portion covered by the photoresist material 50. When the metal substrate is completely dissolved, the orifice is formed, thereby forming a hole 64 over the thickness of the substrate 56 to communicate with each orifice 62.

The second embodiment of the method according to the present invention is similar to the method described above except that the photoresist peg is aligned with yarns (ie, similar to the conventional method shown in FIGS. 1A-1E). The front and back sides of the substrate are then plated simultaneously with an amorphous nickel- or cobalt-phosphorus alloy.

In this embodiment, selective etching is performed between the opening in the amorphous alloy plated on the back side and the opening of the amorphous alloy plated on the front side, wherein the amorphous alloy on both sides of the front side and the back side is like an etching mask. Will act as

EXAMPLE

The present invention will be described in more detail by the following non-limiting examples. In each example, the plating bath is used to measure the effect of depositing an amorphous nickel- or cobalt-phosphorus alloy on the substrate.

In each of the following examples, the substrate is cleaned of the surface using an alkaline cleaning solution and then the substrate is immersed in an alkaline solution at 180 ° F. for about 4 minutes, followed by rinsing with deionized water. And electrolytic cleaning in 10% sulfuric acid (positive) solution at a current of 40 amps / ft ² for 4 minutes at 160 ° F., followed by a cathodic sulfate cleaning at 4 amps / ft ² for 4 minutes. After each of these cleaning treatments, the substrate is rinsed thoroughly with deionized water. Finally, the substrate is immersed in a 10% hydrochloric acid bath and rinsed with deionized water for about 1 minute. The substrate surface is thereby thoroughly cleaned so that contaminants are completely removed.

Kodak's KTFR photoresist coating material is 30 cm poise and attached to both sides of the substrate by pulling it out of the bath bath at a speed of 4 inches without stirring, for one minute, while the photoresist material is continuously Keep clean by filtration. The photoresist plating is then dried for 30 minutes, pretreated for 20 minutes in a 100 ° C. oven and then trimmed to a suitable size. The exposure of the photoresist is performed by placing the plated substrate in a master mask so that only the desired area is exposed. The plated substrate and the master mask are placed in a vacuum bag at 25 inch Hg pressure and exposed to 15 mm watts / cm ² of light. Subsequent development operations include spraying the exposed area for about 105 seconds using a Kodak micro resist developer. The developed area is then removed with Kodak microresist rinse, followed by air drying for about 5 minutes and final heat treatment for 20 minutes at a temperature of 140 ° C. in a reflux oven. The substrate is then activated by bipolar electrolytic cleaning at a temperature of 180 ° F. for 30 seconds, then rinsed with deionized water, immersed in 10% hydrochloric acid solution at room temperature, and woodnickel strike for about 4 minutes at 20 litres / ft ² . Strike with.

Electroplating is carried out in a bath of the composition described below. After plating, the final rinse with deionized water and the plated substrate is trimmed to the final dimensions. The photoresist peg is peeled off and removed by Fremont 561 (a photoresist stripper manufactured by Freemont Industries of Minnesota Shakopee) in an ultrasonic cleaner.

Orifice formation is performed by etching the substrate at a rate of about 0.0571 inches / second at a spray pressure of 18 psi at 130 ° F. with 50% FeCl ₃ /50% deionized water in the substrate. The etched plate is dried by dry nitrogen gas and again dried in a reflux oven at 140 ° C. for 15 minutes.

The final cleaning of the orifice plate is carried out by exfoliating the remaining pot resist using Fremont 561 in an ultrasonic cleaner for 6-7 minutes followed by electrolytic cleaning (negative) at a current of 2 amps for 4 minutes.

In the general process, the electroplating bath is illustrated below.

Example I

A 5 mm thick 316 stainless steel substrate was polished and electroplated in a bath of the following composition.

(a) Bathtub composition 0.75M NiCl ₂ 6H ₂ O

0.25M NiCO ₃

1.20MH ₃ PO ₃

(b) Plating condition

Temperature = 80 ℃

Current density = 150 milliamps / cm ²

The plated 316 stainless steel substrate showed excellent corrosion resistance as it was etched with heated ferric chloride to form the required orifice.

Example II

Example I was repeated using the next composition electroplating bath.

(a) Bath ingredient 0.80M NiSO ₄ 6H ₂ O

0.20M NiCl ₂ 6H ₂ O

0.50MH ₃ PO ₃

0.50MH ₃ PO ₄

(b) Plating condition

Temperature = 80 ℃

Current density = 150 milliamps / cm ²

The plated 316 stainless steel was etched with heated ferric chloride to form the required orifice, which showed excellent corrosion resistance.

Example III

Example I was repeated except that titanium was used as the substrate instead of 316 stainless steel. Etching was performed using a solution of potassium fluoride and hydrogen fluoride. Similar corrosion resistance properties were observed.

Example IV

Example II was repeated except that zirconium was used instead of the 316 stainless phase as the substrate. Etching was performed using a solution of potassium fluoride and hydrogen fluoride. Similar corrosion resistance properties were observed.

Example V

The polished 5 mm thick 316 stainless steel substrate was electroplated in a bath of the next composition.

(a) Bathtub composition 0.76M CoCl ₂ 6H ₂ O

0.24M CoCO ₃

0.50MH ₃ PO ₄

0.50MH ₃ PO ₄

(b) Plating condition

Temperature = 75 ~ 95 ℃

Current density = 200 milliamps / cm ²

The orifice plate obtained by etching with heated ferric chloride showed high corrosion resistance.

Example Vl

The polished 5 mm thick 316 stainless steel substrate was electroplated in a bath of the next composition.

(a) Bath Component 1.0M CoCl ₂ 6H ₂ O

1.0MH ₃ PO ₃

1.0M NH ₄ OH

(b) Plating condition

Temperature = 75 ~ 95 ℃

Current density = 100 milliamps / cm ²

EXAMPLE VII

Example V and Example Vl were repeated using titanium as a substrate instead of stainless steel. Etching was performed using a solution of potassium fluoride and hydrogen fluoride. Similar corrosion resistance properties were observed.

The electroplated substrates of Examples I-V have been shown to be particularly stable at room temperature against inorganic acids such as sulfuric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, and weak organic acids such as formic acid, acetic acid, propionic acid, and oxalic acid. The orifice plates according to the present invention also have stability against strong bases such as hydroxides of sodium and potassium and have been shown to be resistant to weak organic bases such as tertiary or aliphatic amines.

Thus, as can be seen from the above description, improved orifice plates (e.g., fluid jet orifice plates, photoetching masks, etc.) are manufactured to have high corrosion resistance to corrosive fluids, such as those used in the textile industry, for example. Can be. However, the present invention can be applied in addition to the textile industry as is well known, so that the orifice plate manufactured according to the present invention is required to use corrosive fluids in connection with any fluid jet technology, or in the photoetching industry. It can be advantageously used in applications requiring corrosive orifice plates.

Thus, while the present invention has been described in terms of the most preferred embodiment, those of ordinary skill in the art will appreciate that the appended claims are intended to include all corresponding methods, processes and / or products of the present invention. It will be understood that many applications are possible by broad interpretation within this range.

Claims (41)

A method of making a perforated member using a chemical corrosive, the method comprising: depositing a layer of amorphous phosphorus-containing metal alloy in a predetermined pattern defining a predetermined arrangement of openings on at least one side of a corrosion resistant substrate, Selectively corroding at least a portion of the substrate by applying a corrosive to selectively corrode the substrate in the vicinity of the opening at a rate significantly greater than that of the alloy layer. 2. The method of claim 1, wherein said alloy layer is comprised of an amorphous nickel-phosphorus alloy and said substrate is stainless steel. The method of claim 2, wherein the phosphorous content of the alloy is about 20 atomic%. The method of claim 1, wherein the alloy layer is composed of an amorphous cobalt-phosphorus alloy. 5. The method of claim 4 wherein the phosphorus content in the alloy is about 12 atomic percent. The method of manufacturing a perforated member according to claim 1, wherein the amorphous alloy layer is deposited on both sides of the substrate. 2. The method of claim 1, wherein said member is a fluid jet orifice plate having a substantially circular opening in a predetermined linear arrangement. 8. The orifice of claim 7 wherein the openings in the orifice plate are the same as those used in the photoetching process used in carrying out the selective chemical etching step, wherein heated ferric chloride is used as caustic. Method of manufacturing a perforated member. A method of manufacturing a perforated member having an opening in a predetermined arrangement, the method comprising: (a) providing a highly corrosion resistant metal substrate, and (b) depositing an amorphous phosphor-containing metal alloy layer on at least one surface of the substrate. Wherein the alloy layer defines a predetermined arrangement of openings that are defined and exposed to corresponding areas of the surface, and (c) heating to corrode the substrate at a significantly higher rate than adhering the metal alloy layer. Selectively etching the substrate adjacent to the region using a caustic agent containing ferric chloride and forming an orifice arrangement through which each stream of fluid can pass. 10. The method of claim 9, wherein the amorphous alloy is an amorphous nickel-phosphorus alloy and the substrate is stainless steel. The method of claim 10, wherein in step (b), the substrate is immersed in an electrodeposition bath consisting of 0.75M NiCl ₂ 6H ₂ O, 0.25M NiCO ₃ , 1.25MH ₃ PO ₃ , and electrophoresis of the amorphous nickel-phosphorus alloy. A method of manufacturing a perforated member, characterized by supplying a current to a substrate so that welding occurs. 10. The method of claim 9, wherein the amorphous alloy is an amorphous cobalt-phosphorus alloy. The method according to claim 12, wherein in step (b), the substrate is immersed in an electric welding bath consisting of 1M CoCl ₂ 6H ₂ O, 1M H ₃ PO ₃ , 1M NH ₄ OH, and electrowelding of the amorphous nickel-phosphorus alloy takes place. A method of manufacturing a perforated member, characterized in that for supplying a current to the substrate. 10. The method of claim 9, wherein the perforated member is a fluid jet orifice plate, and in step (b) a substantially circular opening is arranged in a linear arrangement in the alloy layer, wherein each opening is performed before performing step (c). A method for manufacturing a perforated member, characterized by defining a corresponding substantially circular exposed area on one surface of a substrate. 15. The method according to claim 14, wherein the step (i) of masking a plurality of circular regions on at least one surface of the substrate is performed to prevent the alloy from depositing on the surface between steps (a) and (b). Method for producing a perforated member, characterized in that. 16. The method of claim 15, wherein step (ii) is performed between steps (i) and (b) to mask a portion of the other side of the substrate such that a plurality of circular areas corresponding to the circular areas on one surface of the substrate are defined. Method for producing a perforated member, characterized in that. 17. The method of claim 16, further comprising covering the other side of the substrate using means for preventing the alloy from depositing in step (b). 18. The method of claim 17, wherein step (c) comprises (1) removing the means for preventing the alloy from depositing, and (2) heating the chloride to cause etching of each circular opening defined on the other side of the substrate. Contacting the ferric iron and (3) performing step (2) until an orifice is formed through the substrate corresponding to each pair of circular openings defined on both sides of the substrate. Method of manufacturing the member. A perforated material comprising a substrate of high corrosion resistant metal and an amorphous phosphor-containing metal alloy layer formed on at least one surface of the substrate, the substrate and the alloy layer having a predetermined opening therethrough. absence. 20. The perforated member according to claim 19, wherein the amorphous metal alloy is an amorphous nickel-phosphorus alloy. 21. The perforated member according to claim 20, wherein the content of phosphorus in the alloy is about 20 atomic percent. 20. The perforated member according to claim 19, wherein the amorphous metal alloy is an amorphous cobalt-phosphorus alloy. 23. The perforated member according to claim 22, wherein the content of phosphorus in the alloy is about 12 atomic percent. 21. The perforated member according to claim 20, wherein the substrate is stainless steel. 21. The perforated member according to claim 20, wherein the substrate is titanium. 20. The perforated member of claim 19, wherein the substrate and the alloy layer together define a substantially circular hole of a predetermined linear arrangement to allow a stream of fluid to pass therethrough. 27. The perforated member of claim 26, wherein the perforated member is attached to a fluid jet printing device. 22. The perforated member according to claim 21, wherein the substrate is stainless steel. 22. The perforated member according to claim 21, wherein the substrate is titanium. 21. The perforated member of claim 20, wherein the perforated member is attached to a fluid jet printing device. 23. The perforated member of claim 22, wherein the perforated member is attached to a fluid jet printing device. A hole formed of a stainless steel substrate having an upper and lower surface, and an electrodeposition layer of an amorphous nickel-phosphorus alloy formed on the at least one surface and having a hole defining an orifice to be formed, wherein the substrate defines the orifice. An orifice plate comprising a hole by chemical etching formed in a straight line with. 33. The device of claim 32, further comprising a second layer of amorphous nickel-phosphorus alloy of electrodeposition formed on the other surface, the layer being in alignment with the hole that defines the orifice and the chemically etched hole of the substrate. Orifice plate characterized in that it comprises a hole arranged in the. A substrate comprising a substrate of stainless steel having an upper and lower surface, and an electrodeposited amorphous cobalt-in alloy layer formed on at least one side of the substrate, the alloy layer having an array of holes defining an orifice formed in the layer; An orifice plate comprising a hole formed by chemical corrosion in a line with the hole defining the orifice. 35. The method of claim 34, further comprising a second layer of amorphous cobalt-in alloy of electrical deposition formed on said other surface, said layer defining a hole defining said orifice and a hole formed by chemical etching of said substrate. An orifice plate comprising an array of holes formed in a straight line. A method of selectively chemically etching a substrate member of stainless steel, the method comprising: electrically depositing an amorphous amorphous alloy layer on the substrate member except for regions that are not continuously etched, and the amorphous nickel-phosphorus alloy layer Preferentially etching the portion of the substrate member which is not coated with a heated ferric chloride caustic which acts more strongly against stainless steel than in the corrosion of the alloy layer. 37. The method of claim 36, wherein said phosphorus alloy is comprised of nickel-phosphorus. 37. The method of claim 36, wherein the alloy consists of cobalt-phosphorus. A mask for selectively chemically etching a stainless steel substrate, the mask comprising an electrodeposition layer of amorphous phosphor-alloy that forms a predetermined pattern of holes through which a chemical caustic can pass. 40. The mask of claim 39, wherein the phosphorus alloy is made of nickel-phosphorus. 40. The mask of claim 39, wherein the phosphorous alloy consists of cobalt-phosphorus.

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