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A Long lived Alkaline Stripper for Full-Aqueous Dry Film Photoresist

Resistrip L (RD-56) efficiently removes full aqueous dry film photoresist (Riston¹, Laminar², Aqua-mer³, etc.) from copper substrates quickly and economically, leaving a surface with no residues which is ready to be cleanly etched, or oxided. Resistrip L (RD-56) is notable for clean stripping of extremely fine line/spacing, especially in spray operations. Resistrip L (RD-56) will not tarnish the tin/lead or other exposed plating. A unique corrosion protection system inhibits redeposition of solder. Subsequent etching, cleaning and oxide operations are improved due to reduced copper and solder oxidation. Resist skins are quickly broken into small pieces for easy removal by filtration.

Resistrip L (RD-56) is water dilutable and rinses cleanly. It may be used in either a soak or spray operation. In spray operations a defoamer (Defoamer A, RD-28), may be required.

Resistrip L (RD-56) is diluted with 9 parts of water (to 10% by volume). For extremely fine spacing and increased stripping speed, concentration may need to be increased.

For best results, heat solution to 120º - 150º F. Typical stripping times of 1-5 minutes (soak) and 1/2 to 3 minutes (spray) depend upon film thickness, temperature, concentration and use mode.

Tank Stripping: A two/three tank system is used. With this set-up, the first tank removes most of the resist in 60-90 seconds. The second/third tanks function as rinses to get off the last traces of resist off. The board is then given a water rinse (spray or overflow soak) to remove stripper. Spray rinsing is recommended over immersion rinsing. When the first stripper tank is spent, it is replaced by the second tank, and a fresh second tank is made up.

Spray Stripping: Solution should be filtered for maximum life and to prevent plugging pump and spray heads. Recommended pressure is 25-30 psi. Normally, Resistrip L (RD-56) is used until it is no longer functional and then is replaced. A pH controlled replenishment system is available.

Tanks may be made of stainless steel, mild steel and polypropylene or other alkali-resistant plastic. Quartz, titanium or stainless steel immersion heaters may be used.


Exercise caution when handling.Resistrip L (RD-56) contains strong alkaline ingredients. Avoid contact with skin and eyes. Wear protective clothing. Eye protection (goggles or a full-face shield) is required. Consult Material Safety Data Sheet for further information.

Dispose of in accordance with Federal, State and local regulations. Contact your RD Chemical representative for further information.


Resistrip L (RD-56) is supplied in 55 gallon drums.

¹²³Trademarks of ¹Dupont, ²Dynachem, ³Hercules

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