The developer of the water-soluble dry film is a 1-2% anhydrous sodium carbonate solution with a liquid temperature of 30-40°C. The development mechanism is that the active groups in the unexposed part of the photosensitive film react with the dilute alkali solution to generate soluble substances and dissolve. During development, the active group carboxyl-COOH interacts with the Na+ in the anhydrous sodium carbonate solution to form a hydrophilic group. COONa. Thus, the unexposed part is dissolved, and the dry film of the exposed part is not swollen. The developing operation is generally carried out in the developing machine, and the developing parameters such as the temperature of the developing solution, the conveying speed, and the spray pressure can be controlled to obtain a good developing effect. When developing correctly
The developer of the water-soluble dry film is a 1-2% anhydrous sodium carbonate solution with a liquid temperature of 30-40°C. The development mechanism is that the active groups in the unexposed part of the photosensitive film react with the dilute alkali solution to generate soluble substances and dissolve. During development, the active group carboxyl-COOH interacts with the Na+ in the anhydrous sodium carbonate solution to form a hydrophilic group. COONa. Thus, the unexposed part is dissolved, and the dry film of the exposed part is not swollen. The developing operation is generally carried out in the developing machine, and the developing parameters such as the temperature of the developing solution, the conveying speed, and the spray pressure can be controlled to obtain a good developing effect. The correct development time is determined by the developed point (the point where the unexposed dry film is removed from the printed board). The developed point must be maintained at a constant percentage of the total length of the developing section. If the developed point is too close to the exit of the developing section, the unpolymerized resist film will not be sufficiently cleaned and developed, and the resist residue may remain on the board surface. If the display point is too close to the entrance of the developing section, the polymerized film may be etched and become hairy and lose its luster due to prolonged contact with the developer. Usually, the display point is controlled within 40% to 60% of the total length of the developing section. When using the developing machine, a large amount of foam will appear due to the continuous spraying and stirring of the solution, so an appropriate amount of defoamer must be added. Such as n-butanol, food and medical defoamer, special defoamer AF-3 for printed boards, etc. The initial amount of defoamer added is about 0.1%. As the developer dissolves into the dry film, the foam will increase again, and you can continue to add it in batches. After developing, make sure that there is no excess glue on the board surface to ensure a good bonding force between the base metal and the electroplated metal. It is difficult to see if there is excess glue on the board surface after development. It can be checked with 1% methyl violet alcohol aqueous solution or l-12% sodium sulfide or potassium sulfide solution. There is no change in color after dyeing decamethyl violet and immersing in sulfide. There is surplus glue.
