Production analysis of the hottest printed circuit

Manufacturing analysis of printed circuit board (III)

2 Silk leak printing method

it can be seen from the figure that silk leak printing method only makes silk from black-and-white films after making black-and-white films. Making current circuits on silk is like engraving words on wax paper with mimeograph. After making the silk plate, use a method similar to mimeograph to print the thin copper to be retained on the copper clad plate, print the circuit on the cleaned copper clad plate with anti-corrosion printing material, and dry many search results, which are really not steps such as corrosion after users find the content. Here we mainly introduce the production of silk plate

there are many ways to make silk, and you can make your own photosensitive film. For example, you can prepare a dichromate photosensitive film by adding dichromate aqueous solution to the photographic film, or you can prepare a diazo photosensitive film by adding emulsion weighted nitrogen powder (100:1). You can also buy a photosensitive film that has been made with a speed range, and stick the photosensitive film directly on the silk to make a silk printing plate. The method of making silk plate with photosensitive film is introduced below

production method of silk plate:

⑴ selection of silk

generally, 180-300 mesh nylon wire (also metal wire) can be selected. Then, stretch the silk manually or mechanically, and remove the oil stains on the silk with diluted lye or detergent. Finally, rinse it with water, dry it and apply it to the light sensitive film

⑵ prepare the photosensitive film

according to the size of the black-and-white negative, appropriately enlarge it a little, cut out the photosensitive film of the required size, and gently wipe the talcum powder on the photosensitive film with a silk cloth

⑶ paste photosensitive film

prepare ammonium dichromate aqueous solution with dichromate and water in the proportion of about 4% (weight ratio), evenly coat a layer of ammonium dichromate solution on the wire, then paste the silk photosensitive film on the wire (be careful not to stick the surface with polyester film on the wire), brush the ammonium dichromate solution on the back of the wire again, and finally scrape the polyester film surface with hard rubber or plexiglass scraper to remove bubbles, and then scrape the excess solution on the back. In this way, the photosensitive film is pasted

⑷ drying

a brief introduction to the special testing machine for drying steel strand in Jinan. Bake in the drying box at about 45 ℃ for 10-15 minutes, remove the polyester film after drying, and then put it back to bake for 1-2 minutes

(5) exposure

place the photographic negative flat and close on the photosensitive surface of the silk film. Use a 1000W high-pressure mercury lamp, with the lamp about 30cm away from the photographic negative, and irradiate it for 3-4 minutes for ultraviolet photosensitivity. It can also be exposed to strong sunlight

⑥ development

put the exposed silk into warm water at about 40 ℃, gently swing it for 1-2 minutes, and then rinse it gently with cold water until most of the graphics are displayed

⑺ drying

after developing, put the silk in a ventilated place and dry it naturally, or dry it at low temperature

(8) trim the silk plate

where there is no need for missing printing, repair it with sealing paste. After repairing, seal it with sealing paste

the above is the production process of the whole silk plate

if the self-made photosensitive glue is used to make a silk plate, first clean the silk, then pour the prepared photosensitive glue on one end of the silk, and then use a plexiglass scraper or a hard rubber scraper (the edge of the scraper must be straight without notch) to evenly scrape the glue on the silk. In order to ensure that the adhesive film has a certain thickness, it can be coated on the wire for 3-5 times

the printed circuit board can be made after the wire is made. The printing material can be mixed with talc powder sifted by silk and paint of a certain color to make a printing material with appropriate concentration, and then use a scraper to scrape the circuit onto the clean copper clad plate on the silk

if the silk plate is not used or the figure is damaged, the film can be removed and the silk can be recycled for plate making again