Microcertec, a pioneer in this approach
Since its creation in 2004, Microcertec has been adding value to its precision-machined technical ceramic parts by metallizing them in thin layers. The metal layer is then selectively etched by laser (laser ablation) to create a 3D interconnection circuit (CI3D) on the ceramic. The customer assembles integrated circuit components such as MEMS, lasers, LEDs, CCDs, SDDs, etc. This innovative packaging meets performance requirements in harsh environments, notably for embedded systems (inertial units, lidar, cooled thermal cameras, atomic clocks, etc.) and high-tech instrumentation (Raman and X-ray spectrometry, passive telecoms networks, etc.).
The CI3D is therefore a real circuit made using hybrid microelectronic technology, a guarantee of robustness and reliability, but on which the components are positioned freely in space, and have mechanical functions to simplify assembly and integration operations. The idea is not new: it comes from CI3D on a plastic base that is shaped by molding; hence the acronym 3D-MID for '3D Moulded Interconnect Device'. Associated with the more recent concept of mechatronics and the emerging field of printed electronics, due to the additive nature of its manufacturing processes, the rise of 3D-MID dates back to the 90s, and has now developed in volume markets, mainly mobile telephony (GSM antenna) and automotive (sensors). We'll come back to the advantages of this concept later.
Microcertec's process is based on the sequential combination of its expertise in precision machining of technical ceramics, microelectronics-grade thin-film metallization, and laser engraving of 3D parts. The result is a flexible technology that covers the needs of both rapid prototyping and medium-volume production (a few thousand to tens of thousands per year). Because of its specificity, laser expertise has been integrated into Microcertec, and a technical partnership has been developed for the metallization of technical ceramics. Initially modest, this activity has grown in importance, today representing between 10 and 15% of sales, and finds most of its customers outside France, in niche markets such as space, civil and military aeronautics, telecommunications, and scientific and medical instrumentation.
Why CI3D?
As mentioned above, the CI3D concept is based on the need for freedom of component placement in space, and the addition of mechanical functions to simplify assembly operations and meet space constraints. Another benefit is the ease with which sub-assemblies can be tested. Compared with plastics, technical ceramics and precision machining win the day when the application calls for high mechanical precision, relative component placement, dimensional stability at elevated temperatures, good electrical insulation, dielectric properties for radio-frequency applications, thermal conduction (aluminum nitride), good surface finish and metallization giving access to the assembly processes used in hydride microelectronics, the possibility of hermetic feed-through or hermetic sealing of packaging. The benefits of this combination are functional performance, compactness and weight reduction, as well as reliability and cost. It's not for nothing that a CI3D is in the seismometer currently on Mars!
(https://www.microcertec.com/microcertec-en-route-pour-mars)
The CI3D of the future takes shape
Future developments are under study. Ultra-short lasers are already enabling finer, more selective etching of both the metallization and the ceramic itself. This makes it possible to densify circuits with better resolution, to produce tracks of less than 50 µm in width with a pitch of less than 100 µm, or to improve the performance of microwave circuits with chip cavities that cannot be produced using any other laser. In order to broaden the scope of CI3D applications, and to complement the possibilities offered by current technology, the ceramic support and metallization of CI3D are also destined to evolve towards the additive processes that are currently emerging, opening up access to the design of parts with internal structures, multi-layer circuits, integrating vias, passive components, sensors and also 'printing' chip wiring. Microcertec is gearing up as a technology partner for customers looking for a new generation of CI3D. (link: with a pdf doc section of the site: see).
Authors: Pascal Métayer - Laser micromachining & projects manager , Alain Charbonnier - Technical sales manager