Increased Miniaturization of Surface-Mounted Multilayer Ceramic Capacitors
For several years, Exxelia Technologies has been conducting extensive work to miniaturize the multilayer ceramic capacitors suitable for space use. Two different methods can be used to achieve this goal: reducing the chip size or decreasing the rated voltage and also dielectric thickness (which allows a higher capacitance in a single layer and the stacking of more layers in a given chip thickness).
After the introduction of the 0603 and 16V capacitors in the QPL list, Exxelia Technologies went further in the miniaturization process, testing both methods described here. The company has performed evaluation of the following ranges:
- 0402 size, with a nominal voltage from 10V to 25V
- 10V rated voltage range (from size 0402 to size 1210)
- This paper will present and discuss in detail the key points of this research, including:
- Materials selected (for dielectrics, internal electrodes and terminations)
- Design rules (with a particular emphasis on ceramic layer thickness, margins, covers)
- Process steps (at manufacturing level and controls stages) to guarantee the reliability of thin ceramic layers and such small capacitors
- Mechanical compatibility of the ceramic parts with the mounting board, taking into account the mounting process (reflow and iron soldering)
- Terminations (nickel barrier + tin/lead vs polymer termination + nickel barrier + tin/lead)
Finally, the capacitance ranges that have been evaluated for 10V rated parts and 0402 sizes and that are now passing the qualification process will be presented.
Visit EXXELIA at Space Tech Expo 2017 in booth 5009