Dry Film Soldermask DF975 - Dry-Film Processing
Dry Film Soldermask DF975 are designed to be developed and stripped in mildly alkaline solutions.
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 Soldermask DF975 is extremely flexible, ensuring reliable tenting performance even on large tooling holes, good tenting performance can be achieved with resists of 75 micron and thicker.
The Dry Film Soldermask DF975 has excellent adhesion and definition characteristics producing very high yields on fine line technologies.
On request is available in the following colours: White, Black, Blue, Red, Yellow.
|Pre-lamination||cleaning||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 green
after exposure - glossy dark green
|Post-exposure hold time||time||the total hold time between lamination and development should not exceed 3 days||30 min - 3 days||30 min|
|Development||breakpoint||the image should appear to be 100% developed to the naked eye||40 - 60% of total dev. time||50% of total dev. time (2)|
|chemistry||anhydrous sodium carbonate - Na2CO3 (weight %) (3)
potassium carbonate - K2CO3 (weight %)
|0.80 - 1.20%
0.60 - 1.00%
|temperature||Na2CO3 or K2CO3||32 - 38°C
(90 - 100°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.||-|
|Cure(4)||exposure||UV Lamps with peak emissions at 360 - 380 nm||3 - 5 mJ/cm2||4 mJ/cm2|
|exposure time||100°C±5°C||-||30 min|
|bake||allow temperature of the oven to reach 150ºC before curing||-||100°C±5°C|
|bake time||Alternatively curing can be achieved with 1 hour in the UV unit||-||1 hour|
- 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.
- The recommended breakpoint for DF975 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 DF975 developing solution:
- Soda ash (anhydrous sodium carbonate): Na2CO3
- Sodium carbonate monohydrate: Na2CO3*H2O
- During the final curing step, the board must be baked first and then exposed to the UV source until the prescribed exposure is attained. Exposure can be measured by an International Light A 309 Lightbug. If you do not have a light meter, you can simply expose the baked board to your imaging source for 10 to 12 times as long as your imaging exposure.
- 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%.