Dry-Film Processing - M115i Dry Film Photoresist
Specifications and Processing Guide:
| Process | Parameter | Detail/Notes | Range | Optimum |
| Pre-lamination | drying time | oven @ 110°C±5°C | 15 - 20 min. | 15 min. |
| Lamination | temperature | Dry-film Laminator | 115°C±5°C | 110°C |
| speed | 0.9 m - 1.9 m/min (3 - 6 ft./min) |
1.2 m/min(1) 4 ft./min. (1) |
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| Exposure | Stouffer Step | 21 step, variable neutral density wedge | 7 - 9 | 8 |
| energy | energy density in miliJoules per square centimeter (350 - 420 nm) | 25 - 60 mJ/cm2 | - | |
| time | UV Source | calibrate each roll |
calibrate each roll |
|
| color | initial - glossy light blue after exposure - glossy blue |
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| Post-exposure hold time | time | the total hold time between lamination and development should not exceed 8 hours | 0.25 - 8 hours | 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) |
| temperature | bubble assisted developers | 29°C±6°C | 29°C | |
| spray developers | 31°C±6°C | 31°C | ||
| chemistry | anhydrous sodium carbonate (soda ash, weight%) (4) sodium carbonate monohydrate (weight %) |
0.80 - 0.90% 0.95 - 1.05% |
0.85% 1.0% |
|
| Pre-etch drying | time | 100°C±5°C | - | 5 min. |
| Stripping | chemistry | NaOH (sodium hydroxide) @ room temp. | 1.5% - 3% | 1.5% |
Notes:
- With Hot-Roll Dry Film Laminator, the midrange position of the speed control knob (at 12:00) corresponds to a web speed of approximately 4 feet per minute.
- Strictly speaking, M115i 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 M115i 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 M115i 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.
Please use the following order form for placing your order:
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