Multi-material additive manufacturing of low sintering temperature Bi₂Mo₂O₉ceramics with Ag floating electrodes by selective laser burnout

Abstract

Additive manufacturing (AM) of co-fired low temperature ceramics offers a unique route for fabrication of novel 3D radio frequency (RF) and microwave communication components, embedded electronics and sensors. This paper describes the first-ever direct 3D printing of low temperature co-fired ceramics/floating electrode 3D structures. Slurry-based AM and selective laser burnout (SLB) were used to fabricate bulk dielectric, Bi 2 Mo 2 O 9 (BMO, sintering temperature = 620-650°C, ε r = 38) with silver (Ag) internal floating electrodes. A printable BMO slurry was developed and the SLB optimised to improve edge definition and burn out the binder without damaging the ceramic. The SLB increased the green strength needed for shape retention, produced crack-free parts and prevented Ag leaching into the ceramic during co-firing. The green parts were sintered after SLB in a conventional furnace at 645°C for 4 h and achieved 94.5% density, compressive strength of 4097 MPa, a relative permittivity (ε r) of 33.8 and a loss tangent (tan δ) of 0.0004 (8 GHz) for BMO. The feasibility of using SLB followed by a postprinting sintering step to create BMO/Ag 3D structures was thus demonstrated.

Materials research & measurement needs for ceramics additive manufacturing

“…Using this method, a 3D-printed structure of Bi 2 Mo 2 O 9 with floating Ag electrodes has been successfully fabricated. 49 Another potential application of ceramics AM is in microelectronic packaging, where current scale limitations are limiting the miniaturization of 3D designs, causing technological bottlenecks. One needs to be able to machine features smaller than 10 μm.…”

“…A slurry‐based 3D printing process using selective laser burnout (SLB) of Bi 2 Mo 2 O 9 could achieve satisfactory microstructures, high dielectric constants, and low losses. Using this method, a 3D‐printed structure of Bi 2 Mo 2 O 9 with floating Ag electrodes has been successfully fabricated 49 …”

Direct Integration of Cold Sintered, Temperature-Stable Bi2Mo2O9-K2MoO4 Ceramics on Printed Circuit Boards for Satellite Navigation Antennas

“…[2][3][4][5] Low-temperature co-fired ceramics (LTCC, 700-900 °C sintering temperature) and ultra-low temperature co-fired ceramics (ULTCC, 400-600 °C sintering temperature) can be co-sintered with low cost electrodes (Ag, Cu and Al, etc.). [6][7][8][9][10][11][12][13][14][15] To date, temperature-stable MW ceramics cannot be directly integrated onto polymer-based printed circuit boards (PCBs) in a single deposition step from powder. To revolutionize radio frequency (RF) manufacturing therefore, low loss (high quality factor, Qf ≥ 3000 GHz), temperature-stable (low temperature coefficient of resonant frequency, TCF = +/-3 ppm/°C), medium permittivity (8 < εr < 40) are required that densify at <200 °C and permit printing/pressing directly onto PCBs, reducing the costs and energy used in manufacturing and increasing functionality.…”

Additive Nanomanufacturing of Multifunctional Materials and Patterned Structures: A Novel Laser‐Based Dry Printing Process

“…Therefore, printing multifunctional materials (e.g., ferromagnetic, piezoelectric) and hybrid structures is still a major challenge. [17,[26][27][28][29][30][31][32][33][34][35] Direct printing of multifunctional materials and composites such as titanium dioxdie (TiO 2 ), [36][37][38][39][40][41][42] barium titanate (BTO), [43][44][45] indium tin oxide (ITO) [11,46] opens a new pathway toward the direct manufacturing of devices with complex functionality. This has led to the emergence of laser-based additive nanomanufacturing (ANM) as a promising approach that could enable the synthesis and patterning of a variety of materials with micro/nanoscale resolutions.…”