Ag Paste (Silver Metallization Paste)

For front and back bus contact

Better yields and higher outputs for solar cell manufacturers.

In partnership with Heraeus, Targray offers the HeraSol Ag paste compositions.

These silver metallization pastes are customizable to your process, thus increasing efficiency and fill factor while providing wider processing windows.

The HeraSol compositions are a series of screen-printable front and back side silver conductors for crystalline solar cells. The front side formulation is ideal for lightly-doped emitter designs and optimized for high throughput processing to deliver excellent aspect ratios and fine line resolution. For back side solder applications, the new lead-free silver paste significantly lowers material consumption due to high coverage and excellent initial and soldered age adhesion.

Benefits

• HeraSol Ag metallization pastes are all very high quality and uniformly consistent from batch to batch.
• Customizable to your unique wafer design and processes.
• All formulations cadmium-free. Lead-free pastes also available.
• Formulations suitable for SiNx or TiOx anti-reflective coatings are available.
• Co-fireable with commercial back side Ag/Al pastes.

Customized Ag Paste Solutions

Targray offers a variety of standard formulations or customized Ag paste solutions for your specific requirements. Heraeus’ state-of-the-art paste manufacturing technology allows fine-tuning of the size, shape and distribution of particles for optimum paste performance.  All of our Heraeus Silver metallization pastes are specially formulated to provide higher efficiencies and wider processing windows, resulting in better yields and higher output for cell manufacturers.

Metallization Pastes for Conventional c-Si Solar Cells
Pastes	SOL952	SOL953	SOL9235H(L)	SOL9273M	SOL9318	SOL230(x)***
Description	Front-side Ag conductive paste	Front-side Ag conductive paste for high sheet resistance emitter	Front-side Ag conductive paste	Front-side Ag conductive paste	Pb-Free front side Ag conductive paste	Back-side Ag paste for solderable busbar application
Sheet resistance applicable	≤ 70 ohms/sq	≤ 80 ohms/sq, shallow emitter	≤ 70 ohms/sq	≤ 80 ohms/sq, shallow emitter	< 70 ohms/sq
Glass frits	Cd free	Cd free	Cd free	Cd free	Cd free, Pb free	Cd free, Pb free
Viscosity*	180 – 240 kcps	180 – 240 kcps	320 – 360 kcps (280 – 320 kcps)	330 – 370 kcps	300 – 350 kcps	100 – 160 kcps
Solids content	84.0 ± 1%	84.5 ± 1%	89.5 ± 1%	89.5 ± 1%	89.0 ± 1%	71.5 ± 1%
Solderability	Sn62 / Pb36 / Ag2 or Sn96.5 / Ag3.0 / Cu0.5
Wafer types	monocrystalline and multicrystalline silicon
Wafer surface treatment	Textured	Textured	Textured	Textured	Textured	Textured/planar
Anti-reflection coating	SiNx:H	SiNx:H	SiNx:H	SiNx:H	SiNx:H
Print screen	280 – 325 mesh S/S screen
Screen emulsion thickness	15 – 25 µm	20 – 25 µm	20 – 25 µm	20 – 25 µm	20 – 25 µm	10 – 15 µm
Drying	150 °C for 10 minutes in circulated air oven or 250 - 300 °C for 20 seconds in belt dryer
Firing	IR belt furnace, Spike Fire
Peak firing temperature** (not setpoint temperature)	740 – 800 °C	740 – 800 °C	740 – 800 °C	740 – 800 °C	740 – 800 °C	725 – 825 °C
Printed thickness (after fired)	15 – 20 µm	15 – 25 µm	20 – 30 µm	20 – 30 µm	15 – 25 µm	5 – 12 µm
Thinner	RV – 354					RV – 507
Shelf lifetime	6 months
Storage	5 – 25 °C  - Do not refrigerate
Usage	Allow paste to come to room temperature prior to opening - Spatulate well before using
*Brookfield HBT, SC4-14 Spindle in 6R Utility Cup @ 10 rpm **Peak firing temperature measured with type-K, 20 gauge thermocouple on surface of wafer. Omega #KMQXL-020G-18 ***SOL230(x): (M)-North America, (H)-Europe, (S)-Asia, (T)-Pb containing

 

Metallization Pastes for Novel Cell Designs
Pastes	CL80-9381M	CL80-9383M	SOL108
Description	Conductive Ag paste for use as second layer in double print process (print / dry - print / dry)	Conductive Ag paste doped with Al for n-type wafer with p+ surface	Low activity Ag for through hole printing (MWT – cells)
Viscosity*	320 – 360 kcps	280 – 320 kcps	17 – 22 Pas at 100 s-1, 25°C, Plate / cone
Solids content	87.5 ± 1%	85.5 ± 1%	87.5 ± 1%
Wafer types	Mono and multi	n-type	Mono and multi
Print screen	280 – 325 mesh S/S screen	280 – 325 mesh S/S screen	230 – 250 mesh S/S screen, 30 µm wire
Screen emulsion thickness	15 – 20 µm	20 – 25 µm	10 – 15 µm (2 ~ 5 µm)**
Printed thickness (after fired)	15 – 20 µm	15 – 20 µm	wafer thickness
Print line resolution (finger width)	≥ 50 µm	≥ 80 µm	50 – 100 µm diameter vias
Thinner	RV – 354	RV – 354
Shelf lifetime	6 Months
*Brookfield HBT, SC4-14 Spindle in 6R Utility Cup @ 10 rpm **Printing with pad

Please ask us about our latest generation of paste for high sheet resistance wafers – SOL9273. Capture an increased efficiency with this cutting edge Ag paste.