In the past, print parameters were often optimised through gradual trial-and-error adjustments. Today, manufacturing operations are under significantly greater pressure in terms of both time and quality. In high-mix production with frequent product changes, extensive test series are rarely feasible. At the same time, implicit process knowledge is diminishing as experienced process engineers retire and are not replaced at the same rate. As a result, the risk increases that print parameters are not optimally matched to solder paste, stencil geometry, and PCB layout, directly affecting volume stability and SPI results.
During production ramp-up, the printing process can quickly become the limiting factor. Repeated test prints to determine suitable parameters prolong the start-up phase and, depending on operator experience, lead to inconsistent results. The goal must therefore be to provide stable, traceable settings in a structured manner right from the start.
Two methodological approaches to parameter optimisation
The challenge is not limited to accurately setting individual parameters such as squeegee pressure, print speed, squeegee angle, or separation behaviour. What matters is their interaction with solder paste type, stencil thickness, aperture geometry, PCB lay-out, and increasingly, the overall SMT line cycle time. The printing process must neither slow down the line nor compromise quality due to unstable settings.
The Printing Navigator from Fuji supports the determination of suitable print parameters in two ways. First, the system can draw on historical production data. From previous manufacturing runs, parameter combinations that have been evaluated for quality are identified and prioritised. Displayed information includes quality ratings, production results, cycle times, and SPI outcomes. Proven settings can thus be reused reproducibly and transferred to similar products.
Secondly, print conditions can be calculated algorithmically based on defined input parameters such as solder paste type, stencil thickness, or target cycle time. This approach is particularly relevant for new products or when only limited data is available, as it enables a structured initial parameter setup without extensive preliminary trials.
In an advanced functional stage, the Fuji system also considers the cycle time requirements of the entire SMT line. While the original functionality focused primarily on quality optimisation, line cycle time is now explicitly included in the calculation. As a result, the printing process is no longer optimised in isolation for maximum stability, but instead for a defined balance between print quality and line performance. The printer adapts to the line - not the other way around.
In practice, this means that printing conditions can be defined from the first panel onward that match both the material configuration and the required line speed. Production ramp-up becomes more predictable, and reproducibility increases.
Targeted adjustments during ongoing production
Even in series production, parameter optimisation is not a static state. Variations in solder paste behaviour, changing environmental conditions, or specific layout requirements may make adjustments necessary.
Instead of manually and iteratively modifying individual parameters, the operator can use the Printing Navigator to select typical print defects, such as bridging or insufficient paste volume. Based on this input, the system suggests appropriate corrective actions and adjusts parameters within defined process limits.
In the case of bridging, for example, this may involve adapting cleaning intervals or paste filling behaviour. At the same time, the system points out physical root causes that should be checked, such as insufficient contact between PCB and stencil, stencil wear, or PCB warpage. Parameter optimisation thus remains structured and process-safe rather than relying on trial and error.
Print force, speed, and other parameters are adjusted only within system-defined limits. This preserves the mechanical integrity of the machine and keeps the process window under control. All changes are documented and remain traceable, improving transparency, simplifying analysis, and supporting continuous improvement initiatives.
Process discipline remains essential
No matter how powerful intelligent parameter optimisation may be, it cannot replace the physical fundamentals of the printing process. Contaminated or damaged stencils, worn squeegees, insufficient PCB contact, or material aging cannot be compensated for even by optimally calculated parameters.
Regular inspection of machine condition and materials therefore remains a prerequisite for stable printing results. The assistance system structures and accelerates parameter optimisation, but it does not replace process discipline.
Stability through systematic control instead of trial and error
Line-oriented print parameter optimisation affects not only individual assemblies, but the overall performance of the SMT line. When printing conditions are aligned with line cycle time from the outset and adjustments are made in a structured manner, ramp-up phases become more predictable, unplanned stops are reduced, and downstream processes benefit from more stable conditions.
Solder paste printing plays a decisive role early in determining yield or scrap, and thus the efficiency, throughput, and process reliability of the entire line. Those who can define print parameters reproducibly in harmony with line cycle time lay the foundation for stable SMT processes. With the Printing Navigator, Fuji pursues an approach that systematises experiential knowledge, accelerates parameter setup, and links quality with line performance. The result is a printing process that is not only precise, but above all, controllable and predictable, regardless of which operator is at the machine.
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