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Fine etching and printing, coloring and electroplating

making metal signs by etching and electroplating is the most commonly used method in the sign industry. With the development of science and technology, the application of computers, the emergence of materials and the birth of new processes, this ancient and practical method of making signs has injected infinite vitality. The complete combination of printing, photosensitive etching, electroplating and other processes can not only produce more exquisite signs, more gorgeous medals, but also produce infinitely variable daily necessities, gifts and handicrafts

1 fine etching

etching usually refers to the formation of depressions on the surface of metal plates through corrosion and electrolysis to achieve the effect of carving. MoSi2 that can be alloyed with Al can be divided into three types: hollowed out etching, surface etching and two patent applications with both ammonium hollowed out etching and surface etching for a product. Usually, the thinnest line retained in hollowed out etching is about 0.3mm, while our company can produce thin lines of about 0.1mm. Generally, the surface etching can reach 0.15mm lines, while our company can produce 0.04mm thin lines. So it is called fine etching. The process flow of fine etching is basically the same as that of ordinary etching, that is:

substrate cleaning - printing anti-corrosion ink - drying - exposure - Development - etching - film removal - electroplating

the basic operations are as follows:

1.1 pattern and film production

because the products of fine etching have entered the category of art, the shape, layout and color should be considered in drawing, In particular, many artistic effects such as light reflection are well combined with the conditions allowed by the production process. The thinnest wire of hollowed out products should be more than 1.2 times the thickness of the substrate; The spacing of the thinnest lines of the surface etching product should be about 0.16mm, and the ratio of black line to white ground in 0.16mm can be made into 1:3, 2:2, 2:1 depending on the reflectance. There should be clear and accurate alignment crosshairs around the front and back films of double-sided etching products, and both the front and back films should be pasted close to the substrate

1.2 plate treatment (taking copper plate as an example)

the front of the plate is polished with 2400 RPM distribution wheel to achieve the mirror effect. After the foundation is dry, it is then dewaxed, degreased, cleaned and dried for use

1.3 photoimaging photoresist

because the production pattern is very thin. It cannot be repaired after development, so it is particularly important to choose a good photosensitive adhesive. Our company selects Coates photo imaging corrosion-resistant ink, and uses 200 mesh silk full-scale printing under yellow light or red light. The polished surface is printed for the first time, and it is dried at 100 ℃ for 15 minutes, the reverse side is printed for the second time, and then it is dried at 100 ℃ for 30 minutes. Exposure can be carried out only after the surface is cooled and does not stick to hands

1.4 exposure

exposure by aspirated phase machine. The exposure time varies from 20 to 100 seconds. The thinner the line, the longer the exposure time, and vice versa

1.5 development

develop with 3-5% sodium carbonate aqueous solution. The water temperature is about 50 ℃. After a few seconds of blistering, gently brush off the aqueous solution with a soft wool brush, and then rinse twice with clean water until there is no residual glue at all. The wet copper plate can be directly etched, or it can be etched after drying

1.6 etching

two methods can be used for etching:

a, electrolysis: current 15-50a, voltage 3-5v, electrolyte: 20% ammonium chloride, 20% potassium chloride, 20% sulfuric acid, titanium plate for anode. In the process of electrolysis, remove the floating electrolytic copper on the anode in time to ensure the normal flow of current

b, ferric chloride method: select relatively pure ferric chloride to bubble into a 30 Baudrillard solution for flow corrosion. In order to achieve different effects in the same layout, the surface should be cleaned and dried after reaching the lightness requirements for the first time. Apply (print) ordinary corrosion-resistant printing ink on the shallow etching position, and then conduct secondary etching

1.7 film removal

place the etched copper plate in water, sodium hydroxide, potassium cyanide 30:1:0.1 solution, heat it to 70 ℃ for film removal, and clean it to give out light

1.8 electroplating

the copper plate pattern after film removal has been very bright and fine, so there is no need to plating bright copper. Nickel plating can be directly carried out for 40-90 seconds, followed by gold plating and silver plating

2 printing coloring electroplating

in the past, two methods of electroplating coloring were used: manual coloring and electrophoretic coloring. Manual color filling is slow and has poor accuracy, and it is very easy to damage the smoothness of the non colored surface. Electrophoretic coloring:

(1) special equipment is required

(2) there must be a certain batch

(3) limited by the monotonous color of the paint

printing, coloring and electroplating is to use printing methods to print various colors of patterns and words that need to be colored on the metal plates that need to be plated. Then electroplating is carried out to completely solve the defects of the above two methods

substrate polishing, cleaning, printing and coloring (printing and baking) and finally drying at 150 ℃ - 1.5 hours nickel plating (silver)

printing, coloring and electroplating process is as follows:

2.1 cleaning substrate

note:

A: the substrate should be operated with gloves in the whole process from polishing, cleaning, then taking it out of water to printing and drying, and must not be directly touched by hands

b, polish and clean the substrate to achieve all hydrophilic surfaces, and there are no spots after air drying

2.2 make a printing plate

use 300 mesh polyester silk to make a plate, which has good bridging performance, and the residual glue should be thoroughly flushed without trachoma and broken line

2.3 choose the printing ink

choose the metal printing ink with acid resistance, alkali resistance, temperature resistance and strong covering power. Our company uses Seiko 1300 ink

cleaning machine: high density polyethylene, general polystyrene 2.4 fine printing and thorough drying

select the glue with medium and low hardness to scrape and re ink printing, so as to achieve a thick and uniform ink layer without broken lines and trachoma. After printing, one color is baked (100 ℃, 10 minutes), and the last printing is dried at 150 ℃, 1.5 hours

2.5 degrease before plating

after drying, soak it in room temperature degreaser (heated to 60 ℃) for 5-10 seconds to remove oil, and then clean and check whether all the non imprinted areas are hydrophilic. If it fails to meet the requirements, it can be brushed with a nylon brush until it is hydrophilic

2.6 direct nickel plating, gold plating (silver)

generally, copper plating is first followed by gold plating (silver), while the pH value of copper plating solution is 0-1, and the pH value of nickel bath and gold bath is 3 6。 At present, there is no acid resistant ink with a pH value of 0-1 in the world. (Seiko 1300 ink acid resistance is pH value is 3) so direct nickel plating, avoid strong acid, and use nickel to increase and brighten. Although the speed is slower and the cost is higher, it has little impact on products with high value-added coefficient and small batch. During nickel plating, the current is 30a, the voltage is 5V, the cathode moves, and it takes 18-20 minutes to increase by 0.3mm. If it needs to increase again, it can be delayed. After cleaning, gold (silver) is plated