Higher solar cell efficiency with pre- and post-coating PL inspection

Photoluminescence (PL) inspection stimulates photon emission by illuminating cells with specific wavelengths, revealing critical information about material integrity and electrical properties. LUMI-Q Coating is a photoluminescence inspection system designed for pre- and post-coating inspection. It automatically detects all relevant defects that have a negative impact on cell efficiency. LUMI-Q Coating can be integrated into existing systems without any additional footprint.

Reliable identification of all color and coating defects

The COL-Q optical inspection system is tailored to the needs of gigawatt-level production facilities and reliably identifies all defects on the cell surface. COL-Q inspects at cycle times <0.7 sec on the fly with uncompromised detection performance.

The distinct MultiView technology precisely detects coating defects such as color deviations, color defects, stains, and local deviations in coating thickness (e.g. caused by pin marks) immediately after coating. A map generated through the assignment of defects to the respective wafer position in the coating process (“Boat View”) then visualizes the spatial distribution of defective or conspicuous cells. This precise detection allows the process parameters to be adjusted quickly in the event of coating defects. 

The coated cells are grouped into quality classes based on the coating color, optical coating thickness, homogeneity and detected defects. The system also enables users to automatically remove wafers that do not meet the classification thresholds. As a result, the system both reduces production costs and enables the production of cells with flawless anti-reflection coating.

Reliable pattern inspection for solar cells

The metallization of solar cells is one of the most demanding steps in the production processes: Contact structures are often very thin, and new cell technologies require highest accuracy for positioning of the contacts. At the same time, weaknesses of the metallization process have more influence on the yield than many others do.  

Monitoring the quality of the metallization structures with PRINT-Q significantly reduces production costs by identifying process weaknesses in time. Users can directly optimize their processes before yield loss occursThe inline inspection tool evaluates the metallization process in terms of positioning and quality of the metallization structures.  

It reliably detects defects, such as finger interruptions or finger thickenings, as well as stains and smearings, or ghost plating an finger peeling, directly after screen printing or plating:

• Finger, closing: Interrupts, thinnings, slubs, nodes, paste stains and smearings

• Busbars: absent segment

• Measurement of local fingerwidth, incl. probe regions for comparison with offline data 

• Measurement of grid position, grid distances, busbar positions

Optimized illumination conditions allow for contact pattern inspection on glossy surfaces and alignment control of the laser or IBC contact structures, and contact patterns. High defect contrasts and low background noise minimize overkill and underkill for all solar cell technologies (such as Perc, IBC,…).

Full support of central recipe management

With Connected PV, print recipes are managed centrally and rolled out to every single PRINT-Q system with a mouse click. This minimizes user errors, significantly shortens installation times, and ensures consistent quality settings on all lines. 

Print or plating monitoring at the smallest footprint

PRINT-Q is easy to integrate into any screen printing or plating system, and can even be retrofitted within the smallest space. The collected data can also be transferred to the screen printer to readjust the printing position automatically.

Final quality sorting for solar cell manufacturing

Cell sorting at the end of the line is mandatory for high-value modules of homogenous color. The CELL-Q inline inspection system checks the front or back of solar cells and sorts them into different color and performance classes according to their optical properties. In a single inspection step, CELL-Q checks the print quality and anti-reflection coating of every single solar cell.

All print and color defects are reliably detected for all cell technologies. Additionally, both the surface and the contour are checked for visible defects. This ensures that only homogeneous cells regarding color and performance are processed into a module.

Central recipe management for cell sorting

CELL-Q’s system and software design simplify the recipe exchange, such as the transfer of quality criteria between systems. This flexibility means that the same quality criteria can be applied across multiple production lines, reducing setup workload for new lines, and enabling true benchmarking of production quality across lines, sites, and equipment. 

Easy integration into production lines

CELL-Q combines the functionalities of COL-Q and PRINT-Q in a single system, creating a space-saving and cost-efficient system for sorting cells at the fastest cycle times. CELL-Q is easy to integrate into any sorting unit and can also be integrated bottom-up together with vacuum transport systems