Screen printing photosensitive adhesive and photosensitive film (5)

1. Dichromate emulsion.

Example 1: (S glue)

Emulsion modulation:

Ammonium Dichromate 100g

1 litre of water

4 parts of emulsion

Dissolve 100 grams of ammonium dichromate in 1 liter of water and blend with the emulsion in a 1:4 ratio.

Coating and Drying: The sensitized emulsion is dropped onto a stretched wire mesh and uniformly coated with a scraper. If the silkworm silk screen is only applied on the side in contact with the substrate. For example, when using a nylon mesh, apply it on the back side. Usually apply 2 to 3 times on each side, and use cold air to dry it.

Shaiban: The positive film and the photosensitive film surface closely fit for printing, exposure time should be determined based on the thickness of the photosensitive film. For example: 100V, 30A, 50cm, with arc light exposure time of 4 to 7 minutes.

Development: Immersion in water for a few minutes at the end of the exposure, and then rinse the water from both sides of the screen with a certain pressure, then remove the water and dry it.

Revision: Correct the pinhole and photosensitive film with the emulsion, and then dry it before exposure.

Example 2: (Meinong Wire Mesh)

Emulsion modulation:

1000 g emulsion

Ammonium dichromate 4% 20g

The sensitizing emulsion was prepared by mixing and stirring the aqueous solution of 4% ammonium dichromate with the emulsion.

Coating and Drying: Using a stainless steel coating tank, three consecutive passes of the screen are applied. If these three round trips are regarded as one process, the coating process can be determined according to the number of the meshes. If the mesh is 200 days, 3 to 4 processes can be applied. The drying temperature should not exceed 40°C. It should be ventilated and dried as much as possible.

Shaiban: Appropriate exposure should use Kodak's photographic scale No2, which can be developed between 6th and 8th tone.

Development: The screen should be immersed in water for 2 to 3 minutes after exposure, followed by spray development.

Drying: After the development is completed, the moisture is shaken off and then fully dried with a hair dryer.

Revised: With a well-developed sensitizer, apply pinholes and place where film is missing, dry and then fully expose.

Example 3: (Sodium Zelda Wire Mesh)

Emulsion modulation:

Ammonium Dichromate 115g

Water 1 liter 20 grams

Emulsion 100g

Ammonium dichromate is dissolved in water and then mixed with 5 times the emulsion and stirred well.

Coating and Drying: When the sensitized emulsion is applied to the screen, it shall be applied from the back of the screen except for the first time. The coated photosensitive film shall complete the steps of the printing plate within 8 hours. If there is any remaining sensitizer, it should be placed in a brown bottle and stored in a cool dark place for two weeks.

Shaiban: For accurate exposure, the positive film and the photosensitive film must be completely sealed together. Exposure using fluorescent light, distance 10 cm, exposure time is 4 minutes.

Developing: Expose the screen after exposure to water for a few minutes, then rinse it with water under pressure from both sides of the screen.

Drying: After the development, the water is sucked with absorbent paper and dried with a hair dryer.

Revision: If there is a pinhole or a defect in the plate, it may be smeared with an emulsion, exposed again and used to harden.