DE1043011B - Process for the production of metal mesh networks - Google Patents

Description

GERMAN

The invention relates to the production of metal pocket nets, as they are e.g. B. in television tubes, Electron tubes and the like are used and the eighty to eight hundred or more recesses own per cm.

It has already been proposed earlier (German Patent 880 678) to produce a metal mesh network using a die, which grooves accordingly the pattern of the network to be produced. The die is covered with a metal layer coated and then removed the metal from the sections between the grooves of the die. The die is then removed again from the metal mesh which has been produced in this way. The die can thereby be made that a bare wax surface lines up accordingly, the lineed surface through anodically atomized or made electrically conductive by other means and then electrolytically metal is deposited on the electrically conductive surface. This creates a negative imprint of the lined surface, and from this negative impression becomes a metallic positive, which the die forms, generated by further electrolytic deposition of a metal. After the die with the Metal, which is to form the network, is coated, the metal is in this process by grinding or lapping removed so that the die is exposed between the grooves and the perforations are formed will.

It might appear possible to etch or dissolve the metal in the metal to be removed a suitable reagent to remove. But it has been found that the etching is by no means uniform is when a metal is immersed in an etching solution and that certain areas of the metal be attacked by the etching solution in a manner that cannot be determined in advance. In the effort to be a Make a mesh from the above-mentioned, metal-coated die by immersing it in an etching solution, it was found that an indiscriminate etching had the effect that in some places some of the ridges formed by settling the metal in the grooves of the die were completely etched away before thinner metal surfaces were perforated on other parts of the die.

The present invention provides an improved method for producing a metal net, in which the metal to be removed is decomposed in a controllable manner in order to produce the perforation. According to the present invention, the method for the production of metal mesh nets consists of a metal part, which consists of ribs which correspond to the network to be produced, and of thin surfaces, which between these ribs He method of production
of metal mesh networks

Applicant:

Electric & Musical Industries Ltd.,
Hayes, Middlesex (Great Britain)

Representative: Dipl.-Ing. W. Bischoff, patent attorney,
Hanover, Am Klagesmarkt 10-11

Claimed priority:
Great Britain June 19, 1951 and June 10, 1952

Herbert Edward Holman, West Drayton, Middlesex, and Leslie James White, Hayes, Middlesex

(Great Britain),
have been named as inventors

gen, in that the whole metal part is intermittently subjected to decomposition at intervals during which the metal lying between the ribs mentioned decomposes more quickly is called the ribs mentioned, and that the intermittent decomposition is carried out so long until the areas between the ribs are removed.

In the preferred form of the invention, the metal part which is to form the aforementioned network is only removed from the die when the decomposition process has ended, although, if desired, the part can be removed from the die by dissolving it prior to the decomposition process can.

The intermittent dissolution of the thin surfaces is preferably effected by that the metal part forming the network is immersed in an etching liquid for a certain period of time, removed from this etching liquid, washed and thereby cooled and then again in the etching liquid is immersed. This operation is repeated until a perforated mesh has been created.

Optionally, the etching process can also take place in a liquid, which the metal surfaces for the purpose Perforation of the metal part to be removed is passivated much faster than the surfaces of the ribs and where an electric current is used for intermittent

809 677/736

1 043 Oli

serves to cancel the passivation. Optionally, the metal surfaces can also be decomposed by electrolysis will.

It is known to produce mesh networks so that a template of the network is made of non-vulnerable material is attached to a plate, which is then etched so that the surfaces that are not exposed to the resistant Material are covered, will be decomposed. The method according to the present invention, however, is completely different from these known methods in that the part which must be etched is not with a stencil of the ISetz made of non-vulnerable Material is provided and, in addition, the entire surface of the metal part undergoes chemical decomposition is subjected.

The invention will now be described with reference to the drawing, for example.

Fig. 1 is a cross-sectional view of a metal part mounted on a die;

Fig. 2 shows the mentioned part and the die in an etching solution;

Fig. 3 illustrates the washing process;

Figure 4 shows the cross-section of the part in Figure 1 after partial decomposition has occurred;

Fig. 5 shows the network after completion of the decomposition process, and

Figures 6 and 7 show alternate methods of practicing the invention.

As shown in Fig. 1, the reference numeral 1 denotes the metal part from which the network is to be formed. This metal part is produced in that silver is deposited electrolytically on a copper die 2 which is provided with grooves. The metal part 1 thus includes ribs 3. enclosed surfaces 4, which are thinner than the ribs 3. The surface of the part 1 bears impressions or grooves 5, which inevitably form during the electrical deposition of the metal part 1. The metal part 1 is preferably treated according to the method according to the invention while it is lying on the die 2. The part 1 and the die 2 are immersed in an etching bath 6 as shown in Fig. 2, and connected with the aid of suitable supports 7 for about 15 seconds in the bath 6. The Flächen4 between the ribs 3 may have a thickness of ⁵ / mm have _loO o to ⁷ⁱ⁵ / _1000, while the copper die 2 has a maximum thickness of 0.25 to 0.38 mm. The etching liquid contained in the bath 6 can consist of 19 parts by volume of concentrated sulfuric acid and 1 part by volume of concentrated nitric acid. Such a liquid essentially decomposes the silver and has little effect on the decomposition of the copper. After the part 1 has been immersed in the etching liquid for about 15 seconds, it is removed, washed under running water from a tap 8 (Fig. 3), thereby cooled and, after drying, immersed again in the etching liquid for a further etching period of 15 seconds, then it is removed again, washed, dried and re-immersed.

It was found that during the etching process described, the centers of the surfaces 4, which between the ribs 3 are etched faster than the surface parts in the vicinity of the ribs 3, so that after repeated immersion, the surfaces 4 between the ribs are removed; there remains a structure which has approximately the shape shown in FIG. Once the surfaces 4 have been perforated, the etching faster because the etching liquid accesses the other sides of the surfaces between the ribs Has. After about 12 to 13 immersions, the surfaces 4 are sufficiently removed and the mesh has then a cross-sectional shape as shown in FIG. The copper matrix 2 can now by dissolving of the copper in a suitable agent which will dissolve the copper but not the silver will. Such an agent is, for example, ammonium persulfate. As can be seen from Fig. 5, has finally formed mesh a somewhat convex upper one

ίο Surface 9, which is an advantage, because it makes the Network is strengthened somewhat. For repeated immersion and washing, a total of 10 up to 15 minutes may be required.

The way in which the method according to the invention results in faster etching of the surfaces 4 is still to be seen not entirely recognized, but it is believed that in the thinner areas 4 a faster temperature rise compared to the thicker parts of the ribs 3 takes place. Since the etching is temperature dependent, these surfaces are etched faster than the surfaces of the ribs. Thus, by removing the Part 1 from the etching solution before washing and re-immersing in the etching liquid the thinner Surfaces decompose faster than the other surfaces.

The decomposition is preferably interrupted before the temperatures of all parts of part 1 equilibrate. Washing the part brings about a temperature equalization of all parts of the part 1.

Fig. 6 shows a modified method of making a network in which the part 1 and the Copper die 2 can be immersed in a bath 10. The bath contains an etching liquid which is the surface of part 1 passivated quickly, e.g. B. Dilute Nitric Acid. This passivation stops the decomposition effect on. The passivation is activated by applying an electric current at intervals the part 1 is canceled, the part 1 forming the anode in the bath 10 and a second electrode 11 being provided is. The part 1 and the electrode 11 are connected to a power source 12, from which negative electrical pulses 13 are supplied to part 1 intermittently. For example, the arrangement be such that a pulse of approximately 12 volts is applied to part 1 for 1 to 5 seconds every minute will. It has been found that with such an arrangement the surfaces 4 are decomposed much faster than the ribs, so that ultimately a network results which has the appearance as shown in FIG. It is assumed that the faster dissolution of the areas 4 is due to the fact that a faster Temperature rise in these surfaces takes place than in the surfaces of the ribs 3. As soon as these surfaces become passive, they cool down, and when the current pulse is applied, the Passivity canceled, so that the further etching of the surface 4 can take place.

In the process described above, it may be desirable to keep the baths (Figs. 6 and 7) cold, which can be done by using suitable coolants. The necessary cooling can also be achieved by this caused that the part 1 is kept in motion in the baths.

In a modified method of the invention, the surfaces 4 are decomposed by electrolysis. As in Fig. 7 shown, the part 1 is arranged in a bath 14 which contains a silver cyanide solution, the one Has excess cyanide. Part 1 is connected to the positive pole of the power source 15 while the negative pole of the power source is connected to the stainless steel cathode 16. In the case of the FIG

Claims (7)

1043 Oil, it has been found that the current intensity drops periodically about every half second to a low value and then increases again, although the current source is constant. The electrolysis is thus intermittent and the passivity is canceled intermittently, this process being repeated automatically without the current intensity being intentionally changed. With this method, the current density depends on the shape of the network to be created. For example, a current density of 10 mA / cm 2 can be used for the production of a network from a part 1 which has the dimensions mentioned above, the bath 14 being at room temperature. Although the invention has been described in terms of its application to the production of metal meshes from silver on a copper die, it will be understood that other suitable metals can also be used. 20 F A T E N T A N S P R 0 C H E: 1. Process for the production of a metal mesh network from a metal part consisting of ribs, which correspond to the mesh network to be produced, and of thinner surfaces that between the ribs, is formed, characterized in that a chemical decomposition of the ribs and thinner areas is achieved by intermittently decomposing the metal part in a liquid at such time intervals as that between the ribs lying metal is decomposed faster than the ribs, and that the intermittent decomposition continues until the areas between the ribs are removed. 2. The method according to claim 1, characterized in that the temperature rise, as a result the faster decomposition of the thinner faces compared to the ribs occurs before continuing the intermittent decomposition is compensated. 3. The method according to claim 1 or 2, characterized in that the decomposition effect is interrupted before the rate of decomposition of the thinner surfaces and the ribs is equal to. 4. The method according to claim 1, 2 or 3, characterized in that said metal part exposed to the decomposition effect while lying on a die. 5. The method according to any one of the preceding claims, characterized in that the decomposition effect is obtained by exposing the metal part to the action of an etching liquid will. 6. The method according to claim 5, characterized in that substances are used as the etching liquid which passivate the surface of the part, and that an electric current is intermittent is fed to the metal part, the passivity being temporarily canceled. 7. The method according to any one of claims 1 to 4, characterized in that the thin Interfaces are decomposed by electrolysis. Considered publications:
German patent specification No. 619 465. 1 sheet of drawings 809 677/736 1tt.