Etching and coloring electroplating technology

The use of etching and electroplating methods to produce metal signs is the most commonly used method in the sign industry. With the development of science and technology, the application of computers, the appearance of materials, and the birth of new technologies, this ancient and practical signmaking method has been injected with infinite vitality. Screen printing etched electroplating and other processes are completely integrated, not only can produce more beautiful signs, more magnificent medals, but also produce endless changes in daily necessities, gifts, crafts.

1 Etching usually refers to the generation of depressions on the surface of the metal plate by means of etching and electrolysis to achieve the effect of engraving. It can be divided into hollow etching, surface etching and three kinds of products that have both an ammonium hollow etching and a surface etching. Usually the thinnest etching line is about 0.3mm, and our company can produce about 0.1mm thin lines. Surface etching can usually reach 0.15mm lines, and our company can produce 0.04mm thin lines. So called fine etching. Fine etching process a process is basically the same as ordinary etching, namely:

Substrate Cleaning - Ink Resist Printing - Drying - Exposure - Development - Etching - Defilming - Plating

The basic operation is as follows:

1.1 pattern and film production

Because the finely etched products have entered the scope of the artwork, the graphics, layout, color, and especially the reflection of light and many other artistic effects should be combined with the conditions allowed by the production process. The thinnest line of hollow products should be 1.2 times or more than the thickness of the substrate; the thinnest line spacing of surface etching products should be about 0.16mm, which is 0.1:3mm. The ratio of black line to white line can be made 1:3 depending on the degree of reflection. , 2:2, 2:1. The double-sided etching product should be clearly and accurately aligned around the front and back film sheets, and both the front and back sheets should be attached to the substrate.

1.2 Plate treatment (copper plate as an example) The plate surface is polished with 2400 rpm/distribution wheel to achieve a mirror effect, and then go to wax, degreasing, cleaning and drying.

1.3 Screen Printing Photoinduced Photosensitive Adhesive

Because the pattern is very fine. Can not be repaired after the development, so choose a good emulsion is particularly important. Our company chooses Coates photoimaging anti-corrosion inks to print with 200 mesh full screen under yellow light or red light, the first time to print the surface, bake for 15 minutes at 100°C, the second time to print the reverse side, After baking at 100°C for 30 minutes, the surface is not sticky before exposure.

1.4 exposure

Suction plate press exposure. The exposure time ranges from 20 to 100 seconds. The finer the lines, the longer the exposure time and vice versa.

1.5 development

With 3-5% sodium carbonate aqueous solution development, the water temperature is about 50 °C, blisters a few seconds later, with a soft wool brush to gently brush the aqueous solution, and then rinse with water twice, until there is no residue glue. The wet copper plate is etched directly, but it can also be dried before etching.

1.6 etching

There are two ways to etch:

A, electrolytic method: current 15-50A, voltage 3-5V, electrolyte: 20% ammonium chloride, 20% potassium chloride, 20% sulfuric acid, anode titanium plate. During the electrolysis process, the electrolytic copper is left floating on the anode in time to ensure the normal passage of the current.

B, ferric chloride method: use more pure ferric chloride bubble into a 30-degree B solution, flow corrosion. For the same layout to achieve different shades of effect, the surface should be cleaned and dried after reaching the shallowness requirement for the first time. An ordinary etching resistant ink is applied (printed) at the shallow etching, and a second etching is performed.

1.7 In addition to the film

The etched copper plate is placed in water, sodium hydroxide, potassium cyanide 30:1:0.1 solution and warmed to 70°C to remove the film and clean the light.

1.8 Plating

In addition to the copper plate after the film has been very bright, very thin, no need to plate bright copper, nickel can be directly plated for 40-90 seconds, then gold, silver.

2 screen printing color plating

In the past, coloring by electroplating was performed by hand coloring and electrophoretic coloring. Manual coloring, slow speed, poor accuracy, and extreme damage to non-colored surfaces. Electrophoretic coloring: (1) special equipment, (2) certain batches, (3) limited monotonous color paint. Screen printing color plating is to print the various colors on the metal plate to be electroplated by using the screen printing method. Then electroplating is performed to completely solve the defects of the above two methods.

Substrate Polishing and Cleaning - Screen Printing Coloring (Ink Color Printing) - Final Drying 150°C-1.5 Hours - Nickel Plating - Gold Plating (Silver)

Screen printing color plating process flow: the specific operation is as follows:

2.1 Cleaning the substrate

Note: A: Before the substrate is polished, cleaned, and then taken out of water until it is printed and dried, gloves must be worn during the entire process. Never touch it directly with your hands. B, substrate polishing to achieve the surface of all hydrophilic, no markings after drying.

2.2 making a screen printing plate

300 mesh polyester screen plate, the bridge is better, residue should be thoroughly washed and no trachoma and broken lines.

2.3 Choose screen printing ink

The use of acid-resistant, alkali-resistant, heat-resistant, and high hiding power of metal screen printing ink, the company selected Japan Seiko 1300 # ink.

2.4 fine screen printing thoroughly dried

Choose low hardness scratch-residue screen printing ink, to achieve thick and uniform ink layer, no broken lines and trachoma, printed in one color (100 °C, 10 minutes), the last time printed in the drying 150 °C, 1.5 hours .

2.5 Degreasing before plating

After drying, it shall be placed in a room temperature degreasing agent (warmed to 60°C), soaked for 5-10 seconds to remove oil, and then washed to check if all the parts are hydrophilic. Not up to the requirements, you can brush with a nylon brush to achieve hydrophilic.

2.6 Direct nickel plating, gold plating (silver)

Usually electroplating is preceded by copper plating followed by gold plating (silver), while copper plating baths have a PH value of 0-1 and nickel and gold baths have a PH value of 3.8-4.6. 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 off, with nickel to increase, brighten. Although the speed is slower and the cost is higher, it has little effect on products with high value-added coefficients and small quantities. Nickel plating current 30A, voltage 5V, cathode movement, increase of 0.3mm take 18-20 minutes, need to increase again, delay can be. After cleaning and gold plating (silver).