I. Core Research Summary

• Digital slicing algorithm for three-axis equipment-specific gantry platforms

Without requiring a five-axis rotary stage, the system employs only three‑axis XYZ motion. By implementing a three‑layer process control—oblique layered serpentine paths, edge‑filling lines, and surface leveling—it accurately fabricates stepped platforms with standard high‑low‑difference fillet transitions at two height scales: H = 375 μm and H = 1 mm. Furthermore, quantitative formulas are established for calculating the platform’s volume, the number of print layers, and the deposition rate, enabling precise prediction of processing parameters for stepped platforms of any dimension.

• In-situ UV curing combined with a delayed leveling dual-smoothing process

Each layer is printed concurrently with a UV‑curing suppression layer to mitigate stair‑stepping; once all the steps are fully formed, a leveling and cushioning layer is re‑applied, allowing sufficient time for the ink to flow and eliminate step‑like grooves—eliminating the need for post‑processing sanding. This results in a naturally smooth, seamlessly transitioned curved surface, effectively addressing the jagged surface‑roughness defects inherent in layered printing.

• Precise Control System for Deposition Rate

The optimal deposition rate was calibrated at 0.0059 mm³/s; at too low a rate, the terrace height is insufficient and edge cliffs appear, while at too high a rate, material overflows and forms protrusions. A standardized parameter window ensures consistent morphology across batches.

• High-reliability electrical performance of conductive traces on inclined surfaces

Silver nanowire conductive traces were directly written onto the surface of a stepped platform. After subjecting a sample with a 1 mm height difference to five thermal cycles between 25 and 150 °C, the average change in resistance was only −0.06 Ω. Adhesion tests using adhesive tape revealed no delamination of the thin film, no significant drift in resistance, and continuous, unbroken circuitry.

• Five Core Advantages of Alternative Gold Wire Bonding

Leadless arching consumes longitudinal space; pad spacing need not accommodate a capillary‑action zone; high‑density routing eliminates the risk of short circuits; interconnect lengths are shortened, and impedance discontinuities are markedly reduced, making it well suited for high‑density heterogeneous integrated circuits.

II. Complete Preparation Process and Process Advantages of the Aerosol Spray Platform

(1) Full set of rounded‑corner stepped platforms + interconnected wiring printing process

• Glass / FR4 and silicon chip substrate cleaning pre‑treatment for height‑difference compensation;
• The three-axis equipment imports CAD‑based layer‑by‑layer slicing paths, and uses pneumatic atomization for UV curing of NEA121 ink.
• The main body of the stepped, serpentine print is built layer by layer, with slow‑speed overfilling at the end of each layer to close gaps in the sidewalls, while each layer undergoes simultaneous in‑situ UV curing using LEDs.
• Full‑area leveling layer printing, with delayed release of ink fluidity to smooth out layer‑to‑layer stepping.
• Seam-filling printing at the top of the stair platform to eliminate gaps at the interface between the platform and the upper‑level substrate.
• Switch to silver‑nanoparticle conductive ink, use aerosol jet printing to pattern interconnects on a smooth, rounded‑corner stepped surface, and complete circuit formation via low‑temperature sintering.

(II) Five Core Process Advantages (Compared with Dispensing, Gold Wire Bonding, and Five-Axis Printing)

• A standard three-axis machine is sufficient to fabricate 3D transition structures, with extremely low equipment costs.

No expensive five-axis motion platform is required; a standard AJ three-axis aerosol system can handle the fabrication of stepped structures with height differences, making it accessible for small and medium-sized enterprises as well as university laboratories.

• Digital precision shaping ensures controllable dimensional tolerances.

The algorithm precisely calculates the number of terraces, the printing length, and the total deposition volume, enabling standardized reproduction of height differences at the millimeter or micrometer scale; in contrast, the morphology of dispensing‑induced slopes is random and uncontrollable.

• In-situ UV curing combined with a leveling composite process, delivering an exceptionally smooth surface.

Layer-by-layer curing prevents collapse, while a post‑curing leveling layer automatically fills platform steps, eliminating the need for mechanical grinding and enabling direct printing of fine conductive traces without breakage.

• Localized on-demand deposition with extremely low material waste.

Polymer is printed only in the transition zones between elevation differences, which, unlike full‑area lamination, significantly reduces UV ink consumption and is well suited for high‑volume encapsulation production.

• Compatible with all types of metal- and carbon-based conductive inks for integrated molding.

The substrate, interconnect silver traces, and conductive layers are printed continuously on a single machine, ensuring seamless integration between the substrate and the conductive layer and enabling one‑stop fabrication of three‑dimensional heterogeneous interconnections, thereby reducing the need for multiple sequential processing steps.

III. Five Key Technological Innovations

Innovation 1: A Layered Slicing Modeling Algorithm for Three-Axis Dedicated Staircase Platforms

Innovative dual morphological optimization process: edge‑line compensation plus tip tapering

Innovation 3: In-situ Curing – Dual-Stage Leveling with Delayed Flow and Smoothing Technology

Innovation 4: An integrated packaging and interconnect architecture capable of direct uphill climbing.

Innovative 5-Stage Universal Standardized Process Framework for Elevation Differences

IV. Current Industry Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: The procurement and operational maintenance costs of five-axis curved-surface printing equipment are extremely high, making widespread adoption difficult.

Challenge 2: On sloped epoxy‑dispensing surfaces, the uneven texture causes the climbing conductive traces to easily break, leading to open circuits and impedance drift.

Challenge 3: Gold wire bonding consumes substantial vertical and horizontal routing space, and high-density arrays are prone to short circuits.

Challenge 4: Traditional transition structures lack standardized modeling methods, requiring manual path tuning for each new product.

Challenge 5: The single‑step curing process results in pronounced layer‑to‑layer steps, making it impossible to print fine‑pitch traces.

V. Future Diversified Industrial Application Scenarios

• 1 MMIC RF chip high–low differential packaging

• Flexible Hybrid Electronic Embedded Sensor Array

• Three-dimensional integration of micro‑MEMS sensors

• Aerospace Lightweight Heterogeneous Electronics

• Rapid Prototyping in the Laboratory

Figure 1. Illustration: a) Printing conductive traces for electrical interconnection of components mounted on the DLS; b) Achieving smooth transitions between DLSs by injection‑printing a bottom‑fill material.

Figure 2. Sliced geometries corresponding to part orientations of a) 90° and b) 45° relative to the print‑flow direction axis.

Figure 3. Printer orientations relative to the direction of rounded‑corner structures printed on the DLS surface in inkjet printing: a) at 90° to the ink‑flow axis; b) at 45° to the ink‑flow axis.

Figure 4. Rounded‑corner geometries designed for printing with the ink flow direction at a 90° angle to the DLSs. The inset highlights the “spherical” structures that form at the terminations of each printed feature.

Figure 5. Schematic diagram of the main rounded-corner structure (without surface smoothing)

Figure 6. Side-view optical images of rounded corners (H = 1 mm) printed at deposition rates of a) 0.0055 mm³/s, c) 0.0059 mm³/s, and e) 0.0063 mm³/s, along with profilometer cross-sectional views as shown in b), d), and f), respectively.

Table 1. Corner‑rounding printing parameters for a feature height H = 1 mm and 375 µm, with a length l = 10 mm and a deposition rate s set to 1 mm·s⁻¹. The first row of parameters corresponds to H = 1 mm, while the second row corresponds to H = 375 µm.

Figure 7. a) Side-view optical images of an H = 1 mm chamfer (unpolished), b) H = 1 mm, and c) H = 375 µm chamfers (with surface polishing).

Figure 8. a) Schematic illustration of conductive traces printed on the rounded corners at the junctions between DLSs; b) Optical images of silver traces printed on rounded corners with H = 1 mm, and c) H = 0.375 mm; d) Top-view of the printed traces on the rounded corner with H = 0.375 mm.

Figure 9. Measured results showing the variation of resistance in silver conductive traces printed on rounded‑corner surfaces, under conditions of H = 1 mm and 375 µm, as a function of thermal cycling (solid data points) and adhesion testing (hollow data points). Note: The lines in the figure do not represent actual data; they are provided solely as visual guides to facilitate the grouping of related datasets.