Printed circuit manufacturers want to use good dry film to ensure the quality of printed boards, stable production and improve efficiency. In recent years, with the rapid development of the electronics industry, the precision density of printed boards has been continuously improved. In order to meet the needs of printed board production, new dry film products have been introduced, and the performance and quality have been greatly improved and improved.
When using a dry film, a visual inspection should be performed first. Good quality dry film must be free of bubbles, particles, impurities; the thickness of the resist film is uniform; the color is uniform; no glue layer flows. If the dry film has the defects in the above requirements, it will increase the amount of revision after image transfer, and in severe cases, it cannot be used at all. The film roll must be wound tightly and neatly, and the interlayer alignment error should be less than 1 mm. This is to prevent the hot press roll from being stained by the winding error during filming, and the continuous film failure does not occur due to the tight winding. . The polyester film should be as thin as possible. If the polyester film is too thick, the light will be heavily scattered during exposure, which will distort the image and reduce the dry film resolution. The polyester film must have high transparency, otherwise it will increase the exposure time. The thickness of the polyethylene protective film should be uniform. If the thickness is not uniform, the photoresist layer will flow, which seriously affects the quality of the dry film. Generally, the thickness of the photoresist layer is marked on the product packaging sheet or the product specification, and the dry film of different thickness can be selected according to different uses. For example, the printed etching process may select a dry film having a photoresist layer thickness of 25 μm, and the pattern plating process requires a dry film having a photoresist layer thickness of 38 μm. For masking, the thickness of the photoresist should be 50 μm.
When the dry film is attached to the surface of the copper clad laminate under heating and pressing conditions, the temperature of the hot press roller of the laminating machine is 105 ° 10 ° C, the conveying speed is 0.9 to 1.8 m / min, the linear pressure is 0.54 kg / cm, and the dry film Should be able to stick to it.
Photosensitivity includes photospeed, exposure time latitude, and depth exposure. Photospeed refers to the amount of light energy required by a photopolymerizable monomer to form a polymer having a certain resisting ability under ultraviolet light irradiation. When the intensity of the light source and the distance between the lamps are fixed, the speed of the light is expressed as the length of the exposure time, and the short exposure time is the speed of the light. For the purpose of improving the production efficiency and ensuring the accuracy of the printed board, a dry film with a fast photosensitive speed should be selected. .
After the dry film is exposed for a period of time, the photoresist layer has been polymerized in whole or in part by development, and generally the formed image can be used, which is called the minimum exposure time. The exposure time is continued to be lengthened to polymerize the photoresist more thoroughly, and the image size obtained after development still conforms to the size of the master image, which is referred to as the maximum exposure time. Usually the optimum exposure time for the dry film is chosen between the minimum exposure time and the maximum exposure time. The ratio of the maximum exposure time to the minimum exposure time is called the exposure time latitude.
The deep exposure of the dry film is important. At the time of exposure, the light energy is reduced by the effect of passing through the resist layer and scattering. If the transmittance of the resist layer to light is not good, when the resist layer is thick, the exposure amount of the above layer is appropriate, the lower layer may not react, and the edge of the resist layer is not aligned after development, which will affect the accuracy of the image. And the resolution, when the film is severe, the resist layer is prone to warping and falling off. In order for the lower layer to polymerize, it is necessary to increase the exposure amount, and the upper layer may be overexposed.
The developability of the dry film refers to the image effect obtained after the film is exposed, exposed and developed in an optimal working state, that is, the circuit image should be clear, and the unexposed portion should be cleaned without residue. The resist remaining on the board after exposure should be smooth and firm. The development resistance of the dry film means that the exposed dry film is resistant to over development, that is, the development time can be exceeded, and the development resistance reflects the latitude of the development process. The developability and development resistance of the dry film directly affect the quality of the printed board. A poorly developed dry film can cause difficulty in etching. In the pattern plating process, poor development may cause defects such as poor plating or poor adhesion of the plating layer. The dry film has poor development resistance, and during overdevelopment, problems such as dry film peeling and plating plating occur. When the above defects are serious, the printed board will be scrapped.
The resolution refers to the number of lines or spaces that can be formed by the dry film resist within a distance of 1 mm, and the resolution can also be expressed by the size of the absolute size of the line or the pitch. The resolution of the dry film is related to the thickness of the resist film and the thickness of the polyester film. The thicker the resist film layer, the lower the resolution. When the light is exposed through the photographic plate and the polyester film to the dry film, the scattering effect of the polyester film on the light causes the light to be side-fired, thereby reducing the resolution of the dry film. The thicker the polyester film, the more severe the side light rays are. The lower the resolution. The minimum parallel line width that can usually be resolved, the first level index <0.1mm, the second level index ≤ 0.15mm.
The dry film resist layer after photopolymerization should be resistant to the etching of the ferric chloride etching solution, the ammonium persulfate etching solution, the acidic copper chloride etching solution, and the sulfuric acid-hydrogen peroxide etching solution. In the above etching solution, when the temperature is 50-55 ° C, the surface of the dry film should be free from hairiness, leakage, lifting and falling off.
In acid bright copper plating, fluoroborate common tin-lead alloy, fluoroborate bright tin-lead alloy and various pre-plating treatment solutions of the above plating, the film resist layer after polymerization should have no surface hairiness and seepage. Plating, lifting and falling off. After exposure, the dry film can be removed in a strong alkali solution after etching and electroplating. Generally, 3-5% sodium hydroxide solution is used, heated to about 60 ° C, and removed by mechanical spraying or soaking. The faster the speed, the better the productivity. The film-removing form is preferably in the form of a sheet peeling, and the peeled pieces are removed through the filter screen, which is advantageous for the service life of the film removing solution as well as for clogging the nozzle. Usually in the 3-5% (by weight) sodium hydroxide solution, the liquid temperature is 60 ° 10 ° C, the first indicator is the film removal time 30-75 seconds, the second indicator is the film removal time 60-150 seconds, the film is removed. No residue after the glue.
The dry film may become brittle due to evaporation of the solvent during storage, or may be thermally polymerized due to the influence of ambient temperature, or uneven thickness due to local flow of the resist, so-called cold flow, which seriously affects the dryness. Use of the membrane. Therefore, it is very important to store dry film in a good environment. The dry film should be stored in a cool, clean room to prevent storage with chemicals and radioactive materials. The storage conditions are: yellow light zone, the temperature is lower than 27 °C (5-21 °C is the best), and the relative humidity is about 50%. The storage period is not more than six months from the date of shipment, and those who pass the storage period can still use it. Avoid moisture, heat, mechanical damage and direct sunlight during storage and transportation.
In order to avoid leakage exposure and re-exposure during the production operation, the dry film should have a significant change in color before and after exposure, which is the discoloration performance of the dry film. When used as a mask etching, the dry film is required to have sufficient flexibility to withstand the impact of the development process, the liquid pressure of the etching process without cracking, which is the masking property of the dry film.
Silicone rubber insulation cover is an insulation safety protection product that must be used for wiring terminals of power equipment such as transformers, lightning arresters and outdoor disconnecting switches. The product can effectively prevent the original exposed power equipment wiring end due to various reasons (human contact, animal or sundry wiring 5) caused by short circuit or contact caused by power failure, damage to power equipment and electric shock and other accidents.
The general wiring methods for this Transformer Connector Shield includes clamp type and terminal type. The users make orders according to the transformer inlet and outlet lines.
Features:
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2.Radiation cross linking materials (Polyolefin or EPDM rubber ).
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4.Avoid short circuit and leakage.
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8.Customized.
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