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Photoresist Developer RD-39

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Sodium Carbonate Monohydrate

Photoresist Developer (RD-39) is hydrated Sodium Carbonate which dissolves readily in water, giving a buffered alkaline solution for economical development of Riston¹, Laminar² and Aqua-mer³ full aqueous dry films. Photoresist Developer (RD-39) will provide flat trace sidewalls consistently over its useful life, and should be used in conveyorized spray equipment, preferably with pH controlled additions. Conveyor speed should be controlled such that "break point" is at approximately 60% of chamber length.

Make up at 1% by weight, or for every 100 gallons of water, add 8.34 pounds of Photoresist Developer (RD-39) (see caution). Fill 5 - 10 gallon pail with hot (over 120º F) water, mix in Photoresist Developer (RD-39) thoroughly, then pour into filled developer sump reservoir. Soft or deionized water is preferred. In the absence of operating instructions from the photoresist supplier, operating temperature is 85 ± 5º F. After developing, thoroughly spray rinse and force air dry. The pH of the operating bath will be 11.4 ± 0.1. Discard when the pH falls below 10.5 or if developing time increases. When the pH is at 10.5, set the break point towards the middle of the developer chamber by adjusting conveyor speed, when the break point goes beyond this set point, dump and remake developer.

Use in specially designed conveyorized spray equipment. Developer equipment should be cleaned regularly using RD Chemical's Equipment Cleaner (RD-34) to maintain quality of developed image.


Harmful if swallowed. Avoid contact with skin and eyes. Wear chemical goggles, gloves and protective clothing. Consult Material Safety Data Sheet for further information.

Spent developer solution should contain extremely low levels of dissolved copper since there are no chelates present. Adjust pH and dispose of in accordance with Federal, State and Local regulations. Contact your RD Chemical representative for further information.


Photoresist Developer (RD-39) is available in 25 Kilogram (55.1 pound) bags. For the user who is not doing a constant replenish, it is recommended that the entire contents of the bag be repackaged into smaller plastic bags containing the exact amount needed to make up the developer sump, this can save embarrassing mistakes that usually occur at the worst possible time.

Caution: Either too little, or too much Photoresist Developer (RD-39) can slow developing speed; measure accurately for maximum efficiency.

To calculate makeup for other sump sizes:

Pounds of Photoresist Developer (RD-39) = sump size (in gallons) X 0.0834

¹²³Trademarks of ¹Dupont, ²Dynachem, ³Hercules

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