LTCC are suitable for multi-layering of circuits by means of simultaneous firing of the ceramic and the internal layer conductors.
Multi-layering permits miniaturization of circuit modules.
- Structural model of LTCC board (examples of boards intended for mounting in vehicles) -
LTCC Multilayer Substrates are made from a single large panel (approx. 200 mm square) . By carrying out the above multi-layering of the circuit, reduction of the number of components, and printing of resistors on the back of the board, the number of units that can be formed inside the panel can be increased, thus enabling the cost of the board to be reduced.
Bare chip mounting
In order to fully utilize the merits of module miniaturization, the ICs used are non-packaged bare dies which are mounted using wire bonds, flip chips, or the like. The surface of Murata's LTCC boards is plated to enable the ICs to be mounted using wire bonds or flip chips.
Installing SMD components
Mounted components are installed using mainly epoxy material from the viewpoint of eliminating the use of lead. The Zero-Shrinkage Sintering Method employed in Murata's LTCC boards enables the component mounting pattern to be formed on the surface of the board with extremely high accuracy, thus facilitating the installation of surface mounted component which are becoming increasingly small each year.
In order to disperse heat generated by the components, thermal vias are provided, enabling the heat from the modules to escape from the aluminum heat dissipation plate on the underside of the board. The inside of the via holes of Murata's thermal vias use the same "silver as that used for the circuit conductors, enabling the heat dissipation performance of the board to be increased.
Resistor printings (rear face of board)
The rear surface of Murata's LTCC Multilayer Substrates has the same kind of ruthenium oxide-based printed resistors formed on it as those used on thick film printed board (HIC) . By using the rear face of the board for forming resistors, the number of solid resistors mounted on the front of the board can be reduced, and also the modules can be reduced in size.
These resistor printings constitute a highly stable system which also enables the board to withstand severe temperature cycle reliability tests for automotive applications.