In the sign making industry, etching signs is a more common type of sign plate. Etching is the technique of removing materials using chemical reactions or physical impacts. Etching techniques can be divided into two categories: wet etching and dry etching. At present, etching signs mainly refer to metal etching signs, and there are also corrosion metal signs. The metal materials used are stainless steel, aluminum plate, copper plate and other metals. The metal etching process sign plate mainly consists of three process links: mask, etching and post-processing. The basic principle of the etching process is to remove the material by chemical reaction or physical impact. Metal etching technology can be divided into two categories: wet etching and dry etching. Metal etching is composed of a series of complex chemical processes. Different etchant agents have different corrosion properties and strengths to different metal materials.

Different types of metal, its etching process is also different, but the general process is as follows:

Pre-treatment: metal etching plate → Oil removal → Water washing → Etching → Water washing → Dry

Etching: Screen printing → Thousands of dry → Water for 2 ~ 3min→ Etched pattern text → Water washing → Ink removal

Post-treatment: water washing → Pickling → Water washing → Electrolytic polishing → Water washing → Dyeing or electroplating → Water washing → Hot water wash → Dry → Soft cloth polishing light → Spray transparent paint → Dry → Inspection → The finished product.

In the process of pre-processing before metal etching, we must do each processing step in accordance with the prescribed process, which is to ensure that the screen printing ink and the metal surface has a good adhesion to the key process, so we must completely remove the oil and oxide film on the metal etching surface. Oil removal should be determined according to the oil pollution of the workpiece, it is best to carry out electric oil removal before screen printing to ensure the effect of oil removal. In addition to the oxide film, the best etching solution should be selected according to the type of metal and the thickness of the film to ensure that the surface is cleaned. To dry before screen printing, if there is moisture, it will also affect the adhesion of the ink, and affect the effect of subsequent pattern etching or even out of shape, affecting the decorative effect.

Etching process can be used to manufacture copper plate, zinc plate and other printing embossing plate, after continuous improvement and process equipment development, it is also used in high-precision equipment. Among them, it is widely used in the processing of thin workpieces similar to the etching of circuit boards and the processing of name plates and thin workpieces that are difficult to be processed by traditional processing methods. It can also be used for precision etching products of electronic wafer parts in the aviation, mechanical and chemical industries, especially in the semiconductor process, etching is an indispensable technology.

Sign plate etching another key step is the production of corrosion resistant layer, common metal plate corrosion resistant layer production methods are as follows:

① With bone glue and ammonium bichromate solution prepared into a photosensitive adhesive coating on the metal plate, after printing, developing, coloring, drying, and then baking, so that the adhesive layer is chestnut skin color, can be used as the corrosion resistance layer of etched labels.

② The photosensitive dry film of the circuit board is heated and affixed to the metal plate, and then the printing plate and development can be used as the corrosion resistance layer of the etched label.

③ With computer lettering, self-adhesive paste on the metal plate, can be directly used as the etching sign corrosion resistance layer.

④ The anti-corrosion ink is printed on the metal plate by the screen printing method to form text graphics, and the anti-corrosion layer of the etched sign can be made after drying.

⑤ By screen printing method, the photosensitive circuit board printing ink is printed on the metal plate, the printing is large field, after drying, the printing plate, development treatment can be used as the corrosion resistance film for etching signs.

After the production of the anti-corrosion film, it can be etched according to the process. The post-treatment of metal etched plates is relatively simple, mainly cleaning and subsequent processing. After the completion of ordinary concave image etching, it is generally necessary to fill paint. It needs to be explained here that the waste liquid generated by etching has a large pollution to the environment, can not be directly discharged into the natural environment, and can be discharged after harmless treatment, which is also a prominent shortcoming of the etching process, there are also engraving methods to replace some metal plate etching, which avoids chemical etching pollution to the environment, but the cost and accuracy need to be improved.