Dry Film Photoresist DF940 - Dry-Film Processing
Dry Film Photoresist DF940 are designed to be developed and stripped in aqueous sodium or potassium carbonate.
It offers superior performance and resistance to leaching in all the most commonly used plating baths used in printed circuit manufacturing. It is highly resistant to acid etching processes.
Our Dry Film Photoresist DF940 is extremely flexible, ensuring reliable tenting performance even on large tooling holes, good tenting performance can be achieved with resists of 40 micron and thicker.
The Dry Film Photoresist DF940 has excellent adhesion and definition characteristics producing very high yields on fine line technologies.
|Pre-lamination||cleaning||mechanical cleaning (pumice or brush) or chemical cleaning. A well cleaned board should be able to keep a water film for at least 20-30 seconds.|
|drying time||oven @ 110°C±5°C||15 - 20 min.||15 min.|
|Lamination||temperature||InGraph Hot Roll Dry-film Laminator||105 - 125°C
(221 - 257°F)
|pressure||2.5 - 3.5 Bar
(35 - 50 Psi)
|speed||1 m - 3 m/min
(3 - 9 ft./min)
4 ft./min (1)
|Post-lamination hold time||time||Minimum: hold time necessary to allow panels to cool down to room temperature
Maximum: the total hold time between lamination and exposure should not exceed 15 days
to maintain the best tenting performances a maximum hold time of 7 days is recommended.
|20 min - 15 days|
|Exposure||Stouffer Step||21 step, variable neutral density wedge||6 - 9||8|
|energy||UV Lamps with peak emissions at 360 - 380 nm||35 - 100 mJ/cm2||55 mJ/cm2|
|color||before exposure - glossy dark green
after exposure - glossy dark blue
|Post-exposure hold time||time||the total hold time between lamination and development should not exceed 3 days||10 min - 3 days||15 min (2)|
|Development||breakpoint||the image should appear to be 100% developed to the naked eye||50 - 65% of total dev. time||60% of total dev. time (3)|
|chemistry||anhydrous sodium carbonate - Na2CO3 (weight %) (4)
potassium carbonate - K2CO3 (weight %)
|0.80 - 1.20%
0.60 - 1.00%
|26 - 32°C
(80 - 90°F)
26 - 30°C
(80 - 86°F)
|pressure||spray||1.2 - 1.8 Bar
(17 - 25 Psi)
|time||breakpoint 60%, D.F. Load 0.15 m2/l (6 feet2/gal)||35 sec.||-|
|Pre-etch drying||time||100°C±5°C||-||5 min|
|Stripping||breakpoint||40 - 60% of total dev. time||50% of total dev. time|
|chemistry||sodium hydroxide - NaOH (weight %)
potassium hydroxide - KOH (weight %)
|1.5 - 3.5%
2.0 - 4.0%
|temperature||40 - 60°C
(104 - 140°F)
|pressure||spray||1.5 - 4.0 Bar
(22 - 58 Psi)
|Proprietary strippers can be used for: Smaller flakes, higher strip speed, reduced copper oxidation and Tin or Tin / Lead attack.|
- With Dry Film Hot-Roll Laminator, the midrange position of the speed control knob (at 12:00) corresponds to a web speed of approximately 1.2 m (4 feet) per minute.
- DF940 can be developed immediately after exposure. We have found, however, that for fine line circuit patterns, letting the panel sit for 15 minutes after exposure enhances the adhesion of the thin traces to the underlying copper.
- The recommended breakpoint for DF940 is 50% of the way though the developing time. The image has reached "breakpoint" when, to the naked eye, the pattern looks to be fully developed. Visual breakpoints can be very misleading. A more accurate evaluation can be made by carefully running your ungloved fingers over the surface of the panel. If you can feel a distinctly slimy or slippery coating in areas that appear to be free of photopolymer, the image needs more time in the developer.
- Two forms of sodium carbonate are commercially available. Both can be used to prepare DF940 developing solution:
- Soda ash (anhydrous sodium carbonate): Na2CO3
- Sodium carbonate monohydrate: Na2CO3*H2O
- If properly imaged, the dry-film should be tough enough after developing to scrub with a kitchen sponge to remove any residual traces of adhesive or photopolymer from the exposed copper areas. This may be necessary if tray or bubble assisted developing is used. Boards developed with high pressure spraying equipment do not generally need this extra attention.
Storage should be in U.V. free conditions with temperature of 20–25°C (59-68°F) and a relative humidity of 40-70%.