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Etching process definition

 

Shenzhen Yaodafa Precision Technology Co., Ltd.-etching process flow video introduction 

The etching process generally refers to photochemical etching, which refers to removing the protective film of the region to be etched after exposure and plate making, and contacting the chemical solution during etching to achieve dissolution and corrosion, forming irregularities or hollow shapes. effect.

Etching is a process that uses this principle to customize the processing of metals.

The origin of etching processing technology 

The origins of etching processing technology can be traced back to the 14th century. At that time, metal etching could only be described as a processing technology, and it could not be raised to the process category, because at the time and hundreds of years later. In the etch, the processing quality is determined by the processor''s own technical level, and not everyone can learn the technology. In the 17th century, the strong etching and strong alkalis such as sulfuric acid, hydrochloric acid, hydrofluoric acid, nitric acid, and caustic alkali were successively invented, and the etching technology was newly developed.
In the late 17th century, people began to use the etching process technology to process the scale of the measuring tool. As a tool, it has been processed differently from the previous art. It requires high consistency of the product, which requires the etching technology to achieve a certain batch. The consistency of the quality of the product requires a specification to precisely define the requirements of each process. In the 20th century, because the technology related to metal etching has been solved successively, and the metal etching technology has gone through hundreds of years of difficult journeys, people have accumulated enough experience and formed the theory of etching on top of these experiences. The etching process has been widely used from aerospace to general civilian products. 

Etching process: 

The type of metal is different, and the etching process is different, but the rough process is as follows: etching processing board → cleaning and degreasing → water washing → drying → film or screen printing ink → drying → exposure pattern → development → water washing and drying → etching →Unloading film → drying → inspection → finished product packaging. 

Degreasing effect

The purpose of degreasing is to remove grease on the metal surface, as a work requiring metal etching, whether it is processing circuit boards or processing general mechanical parts or decorative parts, or processing high-demand parts such as aerospace components or ships. . Some of the workpieces to be processed are patterned, some are structured etching, and some are only chemically etched on one or both sides of the workpiece. The surfaces of these workpieces must first be effectively cleaned. An ideal clean surface must be a surface that removes grease, rust, and scale while washing away various marking symbols and other insoluble foreign materials. The purpose of this cleaning action is to ensure the uniformity of the adhesion of the corrosion-resistant layer to the metal surface and the uniform etching rate.

The role of washing


Water washing is a step that takes a lot in the entire process of metal etching, and is washed after each treatment. The purpose of washing:

a. Washing off the alkaline or acidic liquid film attached to the surface of the workpiece taken out from the alkaline or acidic solution and replacing it with a clean water film to become a clean surface; 

b. When the workpiece is transferred from one process to the next, the solution from the previous process is not taken to the solution in the next process. Therefore, water washing is an important process in the process of metal etching.

The process before the stainless steel or other etching process is cleaned, the main function is to remove the dirt, dust, oil and the like on the surface of the material. Whether this process is well completed is a key process to ensure good adhesion of the film or screen printing ink to the metal surface. Therefore, it is necessary to thoroughly remove the oil stain and oxide film on the metal etching surface. Degreasing should be based on the oil stain of the workpiece. It is best to remove the oil before the screen printing ink to ensure the effect of degreasing. 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 clean. It should be dried before screen printing. If there is moisture, it will also affect the adhesion of the ink, and affect the effect of subsequent pattern etching and even the appearance, affecting the etching effect.

 

  2. Stick dry film or silk screen ink photosensitive layer

Roll-on protective oil principle before etching (applying dry film or screen printing ink)

The rubber roller and the steel wheel are pressed in parallel and rotate inward at a constant speed. The ink is sprayed from the hose to the steel wheel to uniformly adjust the tightness between the rubber roller and the steel roller, so as to control the thickness of the ink adhered to the rubber roller. And the uniformity; the steel sheet is pushed forward uniformly by the conveyor belt, and is properly contacted with the rubber roller, and the ink on the rubber roller is uniformly transferred onto the surface of the steel sheet. The coating technology is widely used in the etching of the anti-corrosion layer. The common coating methods include silk screen printing, dip coating, spray coating, and electrophoretic coating. The surface of the coated anti-corrosion layer should be uniform and complete, without blisters, white spots, etc. If the anti-corrosion layer is found to have the above-mentioned quality defects, and these defects are in the vicinity of the graphic lines, especially the fine graphic lines, the anti-corrosion should be removed. The layer is recoated. After the photosensitive ink sprayed on the workpiece is dried, a quality check is performed before exposure. The inspection items include no scratches on the surface of the ink, pores, and uniformity of the ink. If the requirement is not met, the ink on the entire surface should be re-rolled.

* The adhesion of the photoresist to the steel sheet is achieved by the flow of the photoresist film along the surface of the steel sheet.

* Heating reduces the viscosity of the photoresist and increases the flow. The pressure can squeeze the flow resistance into the surface of the steel sheet. According to the actual product material, the thickness and the precision width of the pattern are confirmed by dry film or wet film screen printing. For different thickness products, when applying the photosensitive layer, it is necessary to take into account the etching processing time required by the pattern of the product, etc., so that A thicker or thinner photoresist layer is produced, so that the hiding performance is good, and the texture of the metal etching process is high.

Rolling principle

 

金属蚀刻前的滚涂原理

 

The shape of the roller should be slightly convex to obtain consistent pressure

 

When the film is applied, the polyethylene film is first peeled off from the film, and then the dry resist layer is pasted on the stainless steel material under heat and pressure. The photoresist layer in the dry film becomes soft after being heated, and the fluidity is increased, and the filming process is completed by the pressure of the hot press roll and the action of the adhesive in the photoresist layer. Dry film photoresist is a photosensitive material developed in the early 1970s. A variety of products have been used to meet different production needs. Dry film has good process performance, excellent imageability and chemical resistance, and has been widely used in circuit board manufacturing, graphic production and cutting of precision parts.

3. Drying of materials and accessories

After the film or roll-on screen printing ink is completed, it is necessary to thoroughly dry the photosensitive layer to prepare the exposure process, and at the same time, it is necessary to ensure that the surface is clean, free from adhesions and impurities. 

4. Exposure

Exposure principle of etching

First, the pattern to be etched is transferred to two identical film films by photolithography, or transferred to two identical glass films by photolithography. The film is then aligned by manual alignment or machine alignment. The steel sheet coated with the photosensitive ink or the photosensitive dry film is placed in the middle of the film, and exposed to vacuum. When the exposure, the steel sheet corresponding to the black portion of the film is not sensitized, and the steel sheet corresponding to the white portion of the film is photosensitive, and the ink or the dry film of the steel sheet is polymerized. Finally, after passing through the developing machine, the photosensitive ink or dry film on the steel sheet is not melted by the developing solution, and the unsensed ink or dry film is dissolved and removed in the developing solution, so that the pattern to be etched is transferred to the steel sheet by exposure.

The exposure is that under the irradiation of ultraviolet light, the photoinitiator absorbs light energy and decomposes into a radical, and the radical initiates polymerization and cross-linking reaction of the non-polymerized monomer, and forms a bulk macromolecular structure insoluble in a dilute alkali solution after the reaction. Exposure is generally carried out in an automatic surface exposure machine. The current exposure machine is divided into air-cooling and water-cooling depending on the cooling mode of the light source. Exposure imaging quality In addition to the performance of dry film photoresist, the choice of light source, control of exposure time (exposure amount), quality of photographic plate, etc. are all important factors affecting the quality of exposure imaging.

When the exposure is insufficient, due to the incomplete polymerization of the monomer, during the development process, the film melts and becomes soft, the lines are not clear, the color is dim, and even the degumming, the film is warped, etched, or even peeled off during the etching process; When it is excessive, it will cause difficulty in development, the film will become brittle, leaving residual glue and other defects. The exposure will produce a deviation in the line width of the image, and an excessive exposure will make the line of the picture thinner and the lines of the product thicker. The appropriate exposure time is determined according to the brightness of the dry film after development, whether the image is clear, whether the image line width matches the original film, and the like. This process is an important process of etching, and the amount of exposure energy is considered according to the thickness of the material of the product and the precision. This is also an embodiment of the technical capabilities of an etching processing company. The exposure process determines whether the etching can ensure better dimensional control accuracy.

5. Development

After the surface of the etched processing layer is exposed to light, the patterned adhesive layer is exposed to light and solidified on the metal plate. Thereafter, unnecessary portions of the pattern, that is, portions to be etched, are exposed. The development process also determines whether the final size of the product meets the requirements. This process completely removes the unwanted photoresist layer that is covered on the product.

6. Etching process or corrosion process

The most critical process, after the product pre-production process is completed. The chemical liquid is etched. This process determines the critical process for the final product to be qualified. The whole process involves the concentration, temperature, pressure, speed and other parameters of the etching solution, and the quality of the product needs to be determined by these parameters.

Etching processing speed and side etching amount

YDF侧蚀量计算

A is the amount of side erosion,H is the etching depth

The two most critical and important parameters in etching process.

The etching speed determines the length of the etching process cycle, the faster the etching rate, the shorter the etching process cycle, the higher the production efficiency, and the lower the production efficiency. However, the etching speed is not as fast as possible:

1. The faster the etching speed is, the larger the etching amount of metal is in unit time, the heat generation is increased, and the temperature of the etching liquid changes rapidly, which is not conducive to constant etching speed;

2, the etching speed is too fast, it is difficult to control the processing of parts with very precise depth requirements;

3. The faster the etching speed, the lower the quality of the metal surface after etching, which obviously affects the smoothness and gloss of the etched surface;

4. High etching rates often require high concentrations of etchant, highly corrosive chemicals, high etch temperatures, and the like. One of these factors increases the cost of the etchant, while increasing the requirements for the resist and increasing the cost.

In addition, high concentrations of corrosive agents and high etching temperatures increase environmental pollution and hazards to operators. In practical applications, for those parts with a large amount of etching, the method of “first fast and then slow” can be used. The so-called "first fast and then slow" is to use an etching solution with a faster etching speed to etch once. When the etching depth is close to the design requirement value, it is replaced with an etching solution with a slow etching speed for precision etching. However, the processing time is shortened while ensuring etching accuracy and surface gloss. As for the determination of the fast etching time, it is necessary to be determined according to the processing requirements of the parts, and generally it is preferable to select 80%-90% of the total etching amount.

Calculation of etching processing time

In the etching process, the parts or the parts that have been subjected to the graphic anti-corrosion layer are placed in the etching solution for etching, and are etched until the thickness of the metal reaches the required level or the depth of the image reaches the requirement. There are three variables throughout the etch process: etch depth, etch rate, and etch time. The relationship between the three is as follows:

V=h/t

Where: V is the etching speed (mm/min), the chemical etching rate referred to herein refers to the etching speed of one side; h is the etching Shenzhen (mm); t is the etching time (min)

This formula is the basic formula for calculating the etching depth and etching speed. The etching of the chemical etching process and the hollow text of the overall etching or molding is often performed simultaneously on both sides. This double-sided etching process is twice as fast as the etching process performed on only one side. In the case of a certain metal material, there are many factors that affect the etching process speed, the most important of which is the type and concentration of the etchant. And etching temperature. If the concentration of the etchant and the etching conditions are constant, the properties of the material and the state of the heat treatment have a great influence on the speed of the etching process.

 7. Unwinding

Principle of stripping

It is heated to a temperature of about 50 °C by a relatively high concentration of NaOH (1-4%). NaOH is highly corrosive, and it chemically reacts with the photosensitive material on the surface of the steel sheet to peel off the photosensitive material on the surface of the steel sheet. . After etching, the surface is still covered with a layer of photoresist. This process requires the photoresist layer on the surface of the finished product to be removed and removed. Since the photosensitive layer is an acidic substance, most of them are subjected to bulking by an acid-base neutralization method, and after overflow washing and ultrasonic cleaning, the surface of the photosensitive layer is removed. This process mainly prevents the residual of the photoresist.

8. After the film is finished, the rest is checked and packaged. The size check ensures that no defective products can flow out to the customer.

Description of some common features of etching process

About the mold opening and cost of etching processing, the relatively low cost of mold opening, in the ordinary case of 200-1000 yuan (special glass mask will be more expensive). The time to update the design is fast, and the design update can be completed in one day and the template can be completed at a lower cost.

Etching Development Cycle for New Products New product development for etching processes can be more flexible and less expensive. Designers can communicate with us in advance when developing new products, so that they can avoid some design flaws after discussion. For example: the material thickness of the design, the processing control precision of the design, the smallest hole that can be etched, the smallest gap, and the like. The design can be sent to the design in advance

E-mail: ly@sz-ydf.com for pre-discussion. Or contact by phone: Liu : +86-135 3425 7051

Some special effects that can be realized: the etching process can achieve the bumping effect of stamping, cutting or CNC not reaching: for example, some LOGO, brand logo, etc., and the stereoscopic effect is strong, the pattern is arbitrary, and the fineness is high.

Some general controllable precision: According to material material, thickness, the processing precision of the factory can be converted into 10% of the thickness of the material, such as 0.1mm thick stainless steel, the control precision is +/-0.01mm

Some shapes of etching process: almost any shape. Depending on the thickness of the material, the smallest opening that can be opened in the shape will vary. The thicker the board, the larger the gap that can be opened. Products with complex shapes can also be etched without additional cost.

Metal etching can process some material thickness. The most ideal condition is: 0.05mm-0.5mm thickness interval. At present, the thickness of the material that can be processed in the factory is controlled at 0.02mm-2.0mm. The thicker the sheet, the longer the etching process will take and the higher the relative cost. At the same time, the processing cost of ultra-thin materials will not be low, and the process control and anti-deformation operations need special treatment.

Etching can process some materials: in theory, all metal materials can be etched or etched. Only different chemical materials are used for different materials, and materials with good corrosion resistance such as gold, silver, etc. even require aqua regia etching recipe to etch. Considering the risk factors and mass production, most of the factory is etched with SUS304, SUS316 stainless steel, and all copper, copper alloy, molybdenum sheet materials can be etched.

Special advantages in etching processing Since etching is performed by means of chemical syrup.

1. The most significant advantage is that the product is highly consistent with the raw materials. Does not change the properties of the material, does not change the material stress (except for the surface half-etching), does not change the hardness of the material, tensile strength and yield strength and ductility. The base processing process is etched in an atomized state in the apparatus, and the surface has no significant pressure.

2. No burrs: During the processing of the product, there is no pressure on the whole process, so there will be no curling, bumping or pressing points.

3. It can complete the separate molding action of the product with the stamping of the post-process, and can carry out the whole plate electroplating, adhesive, electrophoresis, blackening, etc. in a hanging point manner, and the relative cost is more saved. You can contact Mr. Liu by designing the hanging point: ly@sz-ydf.com; 135 3425 7051

4. Miniaturization, diversification can also be handled, and the cycle is short and the cost is small. This provides a better solution for some small or unicorn-type companies at home and abroad, using our dedicated sample set to achieve fast delivery, while ensuring product quality.

Use of etching

1. Production of precision metal parts: The etching process is applied to the processing of special metal parts, which can solve the complicated shape manufacturing. Because the precision tolerance of the parts that can be processed can reach high requirements, it is widely used in automobiles, new energy, precision hardware, aerospace, household appliances, precision digital products, signage, medical equipment, engineering physics, laboratory manufacturing. , consumer electronics, precision filtration and other industries. Other processing techniques such as wire cutting, stamping, electric spark, and the effects and precision that CNC can''''t achieve can be realized.

精密蚀刻

Application of stainless steel etching processing technology

1. Stainless steel etching processing decorative board. The surface of the stainless steel decorative panel has a decorative pattern that is chemically corroded and has a three-dimensional effect. The metal decorative plate may be made of one whole plate or two or more pieces of metal plates, and after being etched with decorative patterns or fine art, it may be combined into a continuous or intermittent piece of decorative plate surface. The metal decorative panel can be a flat surface, an arc, a rugged curved surface, a polygonal surface combination or a degree of folding. The metal etching decorative board is manufactured by first designing decorative patterns according to different user requirements and use occasions, then performing plate making, then performing photosensitive imaging on the surface of the metal plate, performing chemical etching after drying, and street etching. After reaching a certain depth, clean the corrosive liquid, dry it, and then choose different colors for coloring according to the needs or environment. After the coloring, the surface of the metal plate is polished, so that the unetched surface is polished to expose the metal. The natural color, the concave part after corrosion, leaves a color, which brings out the metal pattern or picture of the unetched part to increase the beauty, and finally coats the anti-corrosion layer to complete the manufacture of the metal etching decorative board.

2, imitation stainless steel etching. On the surface of the substrate with metallic specular gloss, the screen printing process is used, and the imitation metal etching ink is printed on it. The dried printed matter makes people feel the unique visual effect: it is like smooth metal corrosion. As elaborated, engraved or sanded, it is elegant, solemn and luxurious. This is the “imitation metal etching process” that is of great concern to the printing industry. This kind of technology is used in some high-end and exquisite packaging cartons. For example: boutique clothing, handicrafts, cosmetics, tea, cigarettes, famous wines and gift boxes. The optical mechanism is: the specular light reflection of the metal texture on the surface of the printing material, forming a strong contrast, which is interesting. The greater the contrast, the better the visual effect. There are two problems to be solved in the process: one is the printing quality of the imitation metal etching ink, and the other is to solve the smoothness of the printing material.

2. The production of the surface pattern: the speciality of the etching process, by covering the photosensitive adhesive layer, it is possible to manufacture some beautiful three-dimensional patterns of the concave and convex. It does not have any effect on the material of the product. The pattern is exquisite and the three-dimensional effect is strong. Widely used in brand identity, gift manufacturing, creative design and other industries.

蚀刻加工

What should I pay attention to during the etching process?

(1) Learn emergency treatment in case of emergency If there is a sudden power outage during production, the medicine tank should be opened immediately to remove the board, avoid excessive etching, such as the conveyor belt blocking plate, immediately close the liquid spray, and open the medicine cylinder to take out the board.

(2) The human link is very important. The environmental conditions of the etching process are relatively harsh. In particular, the ammonia gas is very irritating, and the etching process must be adjusted. The etched machine is “sanded” and the etching parameters are not easy to maintain. . Especially when the board enters the etching tank, it may be a waste and can''''t find the reason.

(3) The safety of etching should be paid attention to. When adding the medicine manually, wear a gas mask or a mask to prevent accidents, especially the smell of ammonia. A large amount of inhalation is harmful to the human body.

(4) Preserving a sufficient amount of mother liquor, there is enough mother liquor to replace one tank of syrup, the extraction of mother liquor is also very important, should be extracted when the ratio of the content of the syrup is optimal, once the syrup is difficult to adjust, the backup mother liquor will play a key role. effect. From this point of view, the etching operation should not be replaced frequently.

(5) The etching process prevents excessive evaporation of ammonia water. As the copper dissolves during the etching process, it is necessary to continuously replenish ammonia and ammonium chloride. The volatility of nitrogen is very large, and usually should not be pumped too much when making a plate, so as not to evaporate too quickly. The consumption of the syrup is increased, and when the plate is not used, it is necessary to remember to close the valve such as pumping, so as to avoid wasted and evaporated. Shenzhen Yaodafa Precision Focus Etching Processing Service ly@sz-ydf.com 

蚀刻加工

Precautions in stainless steel etching process

Processing area: The processing area of stainless steel parts should be relatively fixed. The platform of the stainless steel processing zone should be isolated, such as rubber mats. Stainless steel parts processing area should avoid damage and pollution of stainless steel parts.

Cutting: The cutting of stainless steel parts is cut or plasma cut, sawing, etc.

Machining: Stainless steel parts should also be protected during machining such as turning and milling. When the work is completed, the oil stains, iron filings and other debris on the surface of the workpiece should be cleaned.

Molding processing: In the process of coiling and bending, effective measures should be taken to avoid scratching and creases on the surface of stainless steel parts.

Yaodafa precision professional etch processing services, we are Shenzhen''''s stainless steel etching processing equipment, service-oriented enterprises, focusing on providing metal etching processing, precision etching processing services, to solve various problems in etching processing.

Metal etch processing product connection point design reference

金属蚀刻连接点设计参考

304 etching stainless steel calendering process

The 304 etched stainless steel is also formed by calendering the base material to obtain the corresponding material thickness. At present, the thickness of 304 stainless steel for etching is from 0.02mm to 1.5mm, and the thickness of 304 etched stainless steel which is most suitable for our etching process is generally controlled at 0.03mm-0.05mm. The thickness of the material determines the length of etching process and control accuracy. The final ultra-thin precision stainless steel strip can be obtained by calendering the base metal. And this process also shows the level of a calendering technology. Can you achieve thickness and uniformity, crystal phase stability, and completely create your own technical strength.

304蚀刻不锈钢压延过程

Etching hole density is a very important technical parameter in the etching process

The two most critical and important parameters in etching process. The etching speed determines the length of the etching process cycle, the faster the etching rate, the shorter the etching process cycle, the higher the production efficiency, and the lower the production efficiency. However, the etching speed is not as fast as possible: 1 the faster the etching speed, the larger the etching amount of metal in a unit time, the heat generation is increased, and the temperature of the etching liquid changes rapidly, which is not conducive to constant etching speed; The etching speed is too fast, and it is difficult to control the processing of parts with very precise depth requirements. 3. The faster the etching speed, the lower the quality of the etched metal surface, which obviously affects the smoothness and gloss of the etched surface; 4. High etching speed High concentrations of corrosive agents, highly corrosive chemicals, high etching temperatures, etc. are often required. One of these factors increases the cost of the etchant, while increasing the requirements for the resist and increasing the cost. In addition, high concentrations of corrosive agents and high etching temperatures increase environmental pollution and hazards to operators. In practical applications, for those parts with a large amount of etching, the method of “first fast and then slow” can be used. The so-called "first fast and then slow" is to use an etching solution with a faster etching speed to etch once. When the etching depth is close to the design requirement value, it is replaced with an etching solution with a slow etching speed for precision etching. However, the processing time is shortened while ensuring etching accuracy and surface gloss. As for the determination of the fast etching time, it is necessary to be determined according to the processing requirements of the parts, and generally it is preferable to select 80%-90% of the total etching amount.

Among the metal etched materials, the side etch of copper is the smallest. Generally, copper materials are divided into different grades to correspond to different products. The table below gives you a clear understanding of the correspondence table of different bronze medals at home and abroad, so that friends can choose the materials of the corresponding grades for processing products.

It is precisely because of the problem of etching hole density technology that the number of holes in the product is determined. Not all products have an etched hole density that is more difficult to do, mainly due to the control tolerance of the aperture. For example: 50% etched hole density with 0.1 thick material, and 30% hole density, but the former requires a hole diameter of +/-0.05mm, while the latter requires an aperture tolerance of +/-0.01, then the former Although the density of the etched holes is higher, it is relatively better.

Another problem is that there is also a limit to the density of the etched holes. The thicker the material, the corresponding increase in wall thickness between the holes and the holes. For example, with 0.1mm thick stainless steel, the wall thickness between the hole and the hole can be kept at about 0.2mm, but for a 1mm thick plate, the wall thickness of the hole and the hole should be 0.5mm or more.

In the actual production process, it is necessary to properly grasp the accuracy and application requirements of the product to better solve the problem of etching hole density.

Shenzhen Yaodafa Precision Technology Co., Ltd.

——Design and sales of metal accessories, metal finished products

——One Stop Solutions Provider Of Your Metal Precision Parts

 Mr. Liu:86-135 3425 7051 (with WeChat)   /  86-755-2991 8923

E-mail: ly@sz-ydf.com

Skype:13534257051 / QQ: 252292527/Ali Wangwang : xieliuliu

Company CHN website: www.sz-ydf.com

Shenzhen Address: Building B5, Fumin Industrial Park, Tangwei,Fuyong Town, Bao’an District, Shenzhen China

Dongguan address: 3rd Floor, Building C, Yinfeng Industrial Park, No. 1-3, Nonglin Road, No. 1-3,Humen Town, Dongguan China

 

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