Multimaterial Additive Manufacturing of LTCC Matrix and Silver Conductors for 3D Ceramic Electronics

Abstract

Ceramic electronics have the advantages of large ampacity, high thermal conductivity, and excellent dielectric properties which are widely used in power electronics, optoelectronics, automotive industry, and aerospace technology. This work proposes a multimaterial dispensing additive manufacturing technology for customizing the 3D low‐temperature‐cofired ceramic (LTCC) circuitry. Customized LTCC aqueous slurry is first developed and then 3D printed together with commercial silver paste to build the green body. Then, the green body is debinded and sintered with a three‐stage process at 200, 500, and 850 °C, respectively. The shrinkage rate in 3D is around 17% which is comparable with commercial LTCCs. The surface quality of the sintered ceramic is improved obviously compared with that of the green body due to the glazing effect of the glass phase. For the silver conductor, the resistivity and the temperature coefficient of resistance are 2.34 ± 0.04 µΩ cm and 3.56 × 10−3 °C−1, respectively. A serial of demonstrators including 2D, 3D light‐emitting diode ceramic circuit boards and a ceramic heater/thermometer is developed to prove the potential and feasibility of the proposed technology.

Recent Advances in Multi-Material 3D Printing of Functional Ceramic Devices

“…DIW originated from robocasting technology, which was initially established by Cesarani et al at Sandia National Laboratories in 1997. As an extrusion-based versatile 3D printing method, DIW provides a powerful route for fabricating complex 3D structures with high aspect ratio walls or spanning elements at the meso- and microscale from polymers (conductive or insulating) [ 120 , 121 ], ceramic particles [ 22 , 122 ], metal particles [ 123 ], graphene nanosheets [ 124 ], carbon nanotubes (CNTs) [ 125 ], and composites [ 126 ]. During printing, the ink (also called a suspension or paste) with shear thinning behavior is pneumatically or screw extruded through a motion-controlled nozzle (typical diameter 100–500 µm, Figure 7 a) and then deposited on the platform to form precise patterns.…”

“…Multilayer ceramic substrates are mainly manufactured by HTCC or LTCC technology, which was originally derived from developments at RCA Corporation in the late 1950s [ 230 ]. To meet specific requirements, such as geometric complexity, microscale, multifunction, turnaround time, and cost-effectiveness, significant efforts have been devoted to realizing the multi-material 3D printing of multilayer ceramic substrates in the past few decades [ 22 , 189 , 190 , 191 , 231 , 232 , 233 , 234 ]. For example, Imanaka et al [ 190 ] proposed a hybrid multi-material integration process using the combination of established AJP, chemical etching, sputtering, and plating techniques to fabricate the mesoscale multilayer ceramic structure with fine copper electrodes and vias ( Figure 10 a): employing AJP to deposit high-permittivity BaTiO 3 films, chemical etching to selectively remove materials for shaping the via holes on the as-deposited BaTiO 3 films and internal electrodes on the Cu sputter films, and plating to realize the metallization of via holes.…”

“…Indeed, such a solution coupling SLA with DIW is an advancement for multi-material 3D printing of multilayer ceramic structures (e.g., substrates, solid oxide fuel cells, and customized ceramic electronics); however, it requires an expensive apparatus. Recently, Wang et al [ 22 ] demonstrated a simpler process employing multi-material DIW to fabricate multilayer ceramic structures for a LED substrate ( Figure 10 d) and thermometer ( Figure 10 e). During printing, two independent pneumatic dispensing devices alternatively extruded LTCC slurry and silver paste; once a ceramic layer with reserved trenches and hole vias was finished, the silver paste was filled in the trenches and hole vias to achieve coplanar circuitry and vertical interconnection.…”

“… Schematics of five different 3D printing techniques, including material jetting (MJ), direct ink writing (DIW), fused deposition modeling (FDM), stereolithography (SLA), and digital light processing (DLP), and their applications in single material and multi-material ceramic 3D structures. Schematic images are adapted from [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 21 , 22 , 23 ]. …”

“…( c ) Schematic illustration of the design concept for the HTCC structures ( left ) and photograph of the multi-material 3D-printed HTCC structure (middle) and its SEM image ( right ) [ 191 ]. ( d ) Schematic illustration of the design concept of the multilayer ceramic substrate for a LED ( left ) and photograph of the multi-material 3D-printed multilayer ceramic substrate in a working condition ( middle ) and its micro-CT image ( right ) [ 22 ]. ( e ) Photograph of a multi-material 3D-printed ceramic thermometer [ 22 ].…”