Screen Print Electroplating Of Highly Efficient Solar Cells
At KOENEN we have been manufacturing
precision screens for solar cell electroplating
using emulsion and film technology for over 15 years. KOENEN is a significant
player in the ongoing development of cell electroplating with their
innovative products for front and back surface contacts.
In order to obtain greater solar cell
efficiency, it is important to keep the shadowing effect caused by
the contact finger to an absolute minimum. To meet these requirements,
the screens must be manufactured under clean room conditions, as otherwise
breaks in fingers may occur. The contact line width has to print in
the prescribed line width and depth directly onto the silicon screen
or onto a silicon nitrate anti-reflecting coating.
The following have an influence on the electroplating process:
Choice of frame size, fabric, screen
tension, coating material, coating depth, application
accuracy.
Stainless steel wire fabrics with fine
wire diameters and with are large, open screen areas have proven themselves
for top surface printing. The contact lines can thus be evenly printed
without any breaks.
Recommended fabrics for solar technology
| Mesh | Wire Ø | Mesh size | Open screen area | Surface |
| 400 | 18 µm | 45 µm | 51 % | TS |
| 350 HT | 16 µm | 56 µm | 60 % | TS |
| 325 | 30 µm | 50 µm | 39 % | TS |
| 325 | 24 µm | 53 µm | 47 % | TS |
| 300 HT | 20 µm | 65 µm | 58 % | TS |
| 280 | 25 µm | 67 µm | 53 % | TS |
| 230 | 36 µm | 75 µm | 46 % | BS |
| 230 | 30 µm | 80 µm | 53 % | TS |
| 230 HT | 25 µm | 85 µm | 60 % | TS |
| 200 | 40 µm | 90 µm | 48 % | TS/BS |
| 200 | 36 µm | 90 µm | 51 % | TS/BS |
180 |
45 µm | 95 µm | 46 % | BS |
165 |
50 µm | 100 µm | 44 % | BS |
| TS = Top surface BS = Back surface | ||||
Film and emulsion coatings
Photos 1 and 2 show the comparison between film and emulsion coatings.
Screen with direct-indirect coating
The film coating has a rougher surface
also on the inner edges. The print
shoulder is rounded.
Screen with emulsion coating
Optimal structured screen. The coating edges are smooth, the mesh openings clear and the wires clean. Subsequently optimum paste release can be achieved.
Further details you will receive upon request.
