Solder mask
The protective mask covers the whole PCB surface except for the pads, on which either electronic components will be assembled, or the pads should remain uncovered for some other reason. The minimum spacing between the photo mask and a pad is 0.1 mm, or 0.3mm if epoxy or UV mask is applied. Vias are filled in by epoxy mask (for example when the PCB is fixed by vacuum before testing after assembly). The below pictures shows the conditions, under which the vias can be filled in:
On filling vias in, the min. Spacing between a via and its adjacent pad should be min 0.30 mm.
Standard SET solder masks:
Protective Photo-masks (PETERS)
| Type | Characteristics | |
| Colour: | ||
| ELPEMER SD2467SM-DG | dark green | |
| ELPEMER SD2467SM-YG | light green (yellow-green) | |
| ELPEMER SD2497SM-SG | white | |
| ELPEMER SD2457SM-SM | blue | |
| ELPEMER SD2447SM-SM | black | |
| ELPEMER SD2437SM-DG | red | |
| Standard: | IPC-SM-840C, Class H and T | |
| Hardness | 7H | |
| Permittivity | 93kV/mm | |
| Surface resistance | 1014W.cm | |
| Internal resistance | 1016 W.cm | |
| Taiyo PSR-4000 LEW1(US) 0.8 KG | White |
Epoxy mask (PETERS)
| Type | Characteristics | |
| SD2468 NB-M/21 | Colour: | green |
| Standard | IPC-SM-840C Class H | |
| Permittivity | 111kV/mm | |
| Surface resistance | 1014 W.cm | |
| Adhesion to Cu | very good | |
| Adhesion to Sn/Pb | very good | |
| Resistance to HAL | very good | |
| Protection during wave-soldering | excellent | |
| SD2494 NB-SM | Colour: | green |
| Standard | IPC-SM-840C, Class H | |
| Permittivity | 111kV/mm | |
| Surface resistance | 1014 W.cm | |
| Adhesion to Cu | very good | |
| Adhesion to Sn/Pb | very good | |
| Resistance to HAL | very good | |
| Protection during wave-soldering | very good |
UV mask (PETERS)
| Type | Characteristics | |
| SD2368 UV-SM-DG | Colour: | green |
| Standard | IPC-SM-840C, Class H | |
| Permittivity | 103kV/mm | |
| Surface resistance | 1014 W.cm | |
| Adhesion to Cu | excellent | |
| Adhesion to Sn/Pb | very good | |
| Resistance to HAL | very good | |
| Protection during wave-soldering | excellent |