Inkjet-Assisted Lithography and Electroforming of Complex Micromagnets for Advanced Magnetic Devices

Introduction

Inkjet printing (IJP) is a versatile, accurate, and material-efficient deposition technique that is increasingly employed in advanced manufacturing. Beyond direct material deposition, IJP can be used to fabricate micrometric templates for metal electroforming. In Inkjet Assisted Lithography (IAL), a UV-opaque ink is printed onto a photoresist layer and acts as a customizable photomask [1]. Although its resolution is lower than that of conventional photolithography, IAL is scalable, maskless and applicable to non-standard geometries.

Methods

This work extends the capabilities of IAL from isolated circular features [1] to complex geometrical patterns. Arrays of adjacent droplets were printed and allowed to coalesce into continuous UV-opaque structures. Particular attention was devoted to controlling droplet interaction, edge definition and mask uniformity. The resulting templates were subsequently employed for the electrodeposition of hard magnetic CoNiP and CoPtP alloys. An optimized reverse pulse plating cycle was used to promote uniform filling of the patterns and prevent layer cracking.

Results

The optimized printing conditions enabled the fabrication of continuous photomasks with arbitrarily defined micrometric geometries, overcoming the limitation of previously reported IAL approaches based on isolated droplets. After resist development and electrodeposition, well-defined CoNiP and CoPtP microstructures with minimum feature sizes of approximately 30 µm and a thickness of 10 µm were successfully obtained. The deposited features efficiently reproduced the intended geometries, demonstrating the compatibility of the templates with the electroforming of hard magnetic materials.

Conclusions

The proposed IAL-electroforming strategy provides a flexible and scalable route for producing geometrically complex micromagnets without conventional lithographic masks. The achieved feature size is suitable for applications including magnetic sensors, actuators, energy harvesting systems, and untethered microrobots. These results represent an initial step toward the fabrication of functional magnetic microdevices using a fully customizable hybrid manufacturing approach.

Bibliography

[1] R. Bernasconi et al., Appl. Mater. Today 40, 102365 (2024)