5, for wet plating selection 6, the use of wet film defects: oxygen inhibition 7, the wet film market sales and sales battle 8. Conclusion Double Wire Fence,Double Wire Mesh Fence,Double Loop Wire Fence,Double Barbed Wire Anping County Hua Guang Wire Mesh Production Co.,Ltd , https://www.aphgwirefence.com
First of all, double-sided pattern plating and pattern plating of multi-layered plates should be satisfied, as well as plating of signage panels and metal paintings with strong decorative features.
5.1 Good Thixotropy
The choice of wet film for pattern plating for double-layer and multi-layer rise is more stringent. The first is that the wet film should have good thixotropy and a prescribed viscosity. In the screen printing with the amount of moisture (that is, before the screen printing to make the wet film can run screen version, put a clean white paper on the substrate, squeegee several times on the paper; when the official printing will be cut off the paper) The increase in the number of times, the thinning ink is felt one by one, and the ink is printed on the substrate and the casting is small, and the thickness of the ink is maintained, so that the wet film is prevented from flowing into the hole and shows a good thixotropy.
5.2 resistance to development
Its resistance to development should show a greater latitude in the specified range. Under the specified and correct exposure conditions, lines on the edge of the line or on the pad are not visible after the wet film has been removed. There can be no residual film.
5.3 Good plating resistance
Firstly, it can resist acidic or alkaline degreasing before electroplating, can withstand copper plating, tin-lead, nickel-gold, and pure tin (including black tin plating), and it should not cause peeling, wet film does not fade (does not contaminate liquid chemicals), does not Penetrate, not fall off (previously part of the description). It is easier to remove the film within the specified process conditions.
5.4 Requirements for solids content in wet film composition
For the wet film of electroplating, the solid content should be maintained at 70% to 75%, and no thinner can be added during use. If the viscosity is large, it can be solved with stirring or with coarse screen printing.
5.4.1 Wet Film Solids, Thickness and Plating Relationship
The double layer and multilayer riser are performed during pattern plating: secondary copper plating, pure tin plating (or lead tin or nickel gold). The plating thickness of the hole wall and the surface shall be increased by 0.015 to 0.025 mm as stipulated in the standard, so the wet film resistant to plating shall also reach or approximate this thickness (after drying). If the film is very thin, the coating will have a sharp edge (also known as the pressure edge). After removing the film, there will be a very thin wet film on the two sides of the film being pressed by the coating. After the etching, there will be irregular edges. Less than a steep effect, causing serious scrap.
If the solids content is low, no matter what method is used to print the desired thickness at one time, plugging will occur, which will cause trouble for the next process.
5.4.2 Necessary conditions and calculations for satisfying thickness
In order to meet the required wet film thickness during electroplating, it is necessary to perform mesh selection. Nylon mesh should be selected from the screen material, because it has cheap, low friction coefficient, good ink penetration and smoothness, which saves the operator's effort in manual printing and obtains more ink penetration rate. There are many factors affecting the wet film thickness during screen printing. There are two constants: the screen thickness and the solid content of the wet film. The variables are: scraper hardness, the angle of the squeegee and the substrate at the time of squeegee printing, the size of the squeegee pressure, the number of squeegees, and the speed of scraping India. Here is a formula to participate in: Ft·S
In the formula, Ft is the screen thickness and S is the solid content. In fact, Ft·S is only the theoretical value of the film thickness, but the data provided by the relevant data and the formula out of the larger: that is, the wet film of a squeegee once on the substrate is only 25 to 30% of the net thickness, accurate The calculation must consider the above five variables. Many materials are also listed to provide different thicknesses printed using different numbers of meshes. Practice shows that as the number of nets decreases, the print becomes thicker, but there is a large difference between the identified data. Therefore, we can only select the screen according to the film thickness required by our products, and carefully consider five variables to calculate a more accurate film thickness.
When exposed to a wet film, oxygen inhibition slows the actinic cross-linking until it stops, and in severe cases can make the film surface sticky. There are two aspects of oxygen inhibition: First, the influence of the initiator, but the photosensitizer in the excited state decreases, reducing the initiator's efficiency. The second is the inhibition during the polymerization process.
6.1 Adjusting the Wet Film Formula to Reduce Oxygen Inhibition
In order to avoid the interference of oxygen and to allow the wet film to polymerize successfully in the sun, ink manufacturers and experts have conducted long-term exploration and practice and have found many methods: such as choosing the ideal photosensitive initiating system in the wet film formula, so that Oxygen and curing system isolation; increase the concentration of photoinitiator; select the appropriate resin. Although these methods have achieved certain results, but only to minimize the interference of oxygen, this interference can not be considered in the manufacture of general patterns, but in the production of thin lines or fine patterns must be carefully overcome , otherwise it will not achieve the desired effect (refers to the production of 2mil thin lines and outlets)
6.2 Calculation and Example of Light Energy:
Formula: E=I·T
Where I = intensity, expressed in mv/cm T = time, in seconds,
E = light energy, expressed in mj/cm Example: We measure the light intensity of an exposure machine to 10mv/cm, and the exposure time is 10 seconds:
Common light energy E=I·T=10·10=100mj/cm
Similarly, the light intensity of another exposure machine was measured to be 5 mV/cm, and light energy of 100 mj/cm was also obtained with an exposure time of 20 seconds. However, after exposure and development, observation with 100 × magnifying glass, the latter line becomes thick (positive lines), thinning (vein lines), severe development difficulties. Because the upper layer of the wet film is cross-linked soon after being irradiated with UV light, the latter is injected into the bottom due to the low intensity and the UV light is instantaneously low. At this time, oxygen enters the anoxic exposure area from the non-exposed area, and the time is extended. And the diffusion of light, partial cross-linking and polymerization can not be completed in time, oxygen stays in the exposed area and around. This phenomenon occurs mostly in products with thicker wet film, such as molds, or grids with higher resolution products. Double-sided and multi-layer riser patterns are also in this category.
6.3 Reducing Oxygen Inhibition in the Exposure Process
Another solution is to consider during the exposure process. The solution as described above is to increase the exposure intensity to shorten the exposure time relatively. The dissolved oxygen is faster than oxygen diffusion into the exposed area in a short time. The entire exposure process has been completed when the oxygen in the exposed area has not yet entered the exposed area, and the UV light can be rapidly injected into the bottom of the wet film to complete the polymerization and cross-linking.
It is the wet etching resistance and plating resistance that are used in other industries in addition to the circuit board (as described earlier). Therefore, ink printers at home and abroad have spotted the market and landed on the beach. The first is the Japanese wet film entering the Chinese market, followed by the United Kingdom, Germany, the United States, Italy, South Korea, and Singapore. In China, there are more brands in Taiwan, followed by Beijing, Guangdong, Jiangsu, and Zhejiang. According to my incomplete statistics, there are nearly 30 different brands of wet film in the market competing for sales at home and abroad. As many manufacturers and as many brands as there are no countries that can compare with us, it is truly the best in the world! Therefore, it is a buyer market, we must choose a good wet film with good environmental protection, good quality and reasonable price.
Although the wet film was originally used as a mask for pattern etching and pattern plating of circuit boards, it is widely used for signs, panels, and building materials because of its excellent corrosion resistance, plating resistance, and high resolution. And decoration industry. In particular, the signboard panel industry has replaced dichromate sensitive adhesives to eliminate the emission of hexavalent chromium, which has made a big contribution to environmental protection and improved the working environment for operators. When used for electroplating, the cost is greatly reduced, and the cost of using the wet film in the circuit board industry is only 50% to 65% of the dry film cost, which is its life. At present, its scope of use will continue to expand. Someone asked if wet film will replace dry film in the future? I'm not good at answering, only know that some large-scale printed board factories in the near future are undergoing technological transformation to apply wet film.