Heraeus launches front side silver pastes for ‘knotless screen’ printing

May 9, 2017
Facebook
Twitter
LinkedIn
Reddit
Email
The new SOL9641AX/BX series is designed to realize the full advantages of knotless printing screens and were developed in close collaboration with screen vendors and customers. Image: Heraeus

Heraeus Photovoltaics has introduced specially developed metallization pastes for ‘knotless screen’ printing of solar cells. The new SOL9641AX/BX series is designed to realise the full advantages of knotless printing screens and were developed in close collaboration with screen vendors and customers. Chinese PV manufacturer EGing became the first integrated photovoltaic manufacturer worldwide using knotless screen printing in mass production of c-Si solar cells.

Problem

This article requires Premium SubscriptionBasic (FREE) Subscription

Try Premium for just $1

  • Full premium access for the first month at only $1
  • Converts to an annual rate after 30 days unless cancelled
  • Cancel anytime during the trial period

Premium Benefits

  • Expert industry analysis and interviews
  • Digital access to PV Tech Power journal
  • Exclusive event discounts

Or get the full Premium subscription right away

Or continue reading this article for free

Different from the conventional metal wire mesh, the knotless screen with so-called ‘zero degree mesh’ can give more room for silver paste to go through the mesh compared to conventional screens, while conventional screens usually need adjustment on its printability. However, specially developed metallization pastes are required to maximize the key benefits of knotless screen printing to obtain higher aspect ratio on ultra-fine-line fingers.

Solution

The SOL9641AX and SOL9641BX have been built on two product platforms 9641A and 9641B with the latest breakthrough in organic vehicle system designed for knotless screen with finer fingers than printing though conventional screen. Both 9641AX and 9641BX provide conversion efficiency gains by only the switch in screens, which gives great cost advantage. Compared to conventional paste, 9641AX and 9641BX could achieve much better aspect ratio (AR) for fired fingers (0.3 AR VS 0.5 AR), which results a gain in Isc and FF, therefore providing efficiency improvement. Heraeus said that a 0.1% efficiency gain can be achieved and the pastes are perfectly suited also for black silicon texturing.

Applications

SOL9641AX is suitable for black-silicon with excellent adhesion, while SOL9641BX has a wide process window for PERC and Ultra-lightly-doped-emitters. SOL9641 is compatible with both monocrystalline and multicrystalline wafers. 

Platform

The printability of SOL9641AX/BX has been specifically tailored to knotless screens. It features a unique paste rheology, enabling a significant higher aspect ratio on ultra-fine-line fingers, which can print defect-free through a less than 26μm screen opening in high throughput mass production. Paired with Heraeus’ ‘floating busbar paste’ SOL9622B, further efficiency gains are achieved, compared to conventional pastes. The new pastes are typically dried in an IR dryer with set points of 250 – 300° C in less than 30 seconds or 150 – 200° C for 10 minutes in circulated air oven.

Availability

April 2017, onwards.

Conventional screens limit room for silver paste to go through the mesh. Image: Heraeus

Read Next

Premium
October 14, 2025
OCI Holdings’ decision this week to buy a Vietnamese solar wafer facility to supply the US solar cell manufacturing industry makes clear the biggest vulnerability facing the sector today.
October 13, 2025
Korean chemical production firm OCI Holdings has acquired a 65% stake in a Vietnamese solar wafer production plant, intending to export solar wafers to the US.
October 13, 2025
US solar manufacturer T1 Energy has acquired a minority stake in fellow US-based solar cell producer Talon PV.
October 10, 2025
US solar recycling firm OnePlanet has achieved the R2v3 certification from electronics sustainability non-profit SERI, which represents the “highest standards of traceability”.
October 9, 2025
The retroactive collection of duties on historical solar imports to the US has been temporarily paused pending the outcome of an appeal.
October 8, 2025
US solar module prices jumped in Q3 2025 as developers scrambled to meet the 2 September 2025 safe harbour deadline for Investment Tax Credit (ITC) qualification, according to supply chain platform Anza.

Subscribe to Newsletter

Upcoming Events

Solar Media Events
October 21, 2025
New York, USA
Solar Media Events
November 25, 2025
Warsaw, Poland
Solar Media Events
December 2, 2025
Málaga, Spain
Solar Media Events
February 3, 2026
London, UK