Picosecond Laser Structuring for Low Temperature Cofired Ceramics – an OverviewWednesday (24.06.2020) 16:30 - 16:50 Room 2
Low temperature cofired ceramics (LTCC) provide a large spectrum of functionality, where standard electronics do not fulfill the requirements. LTCC substrates are often used for automotive applications, avionics and space technology. Also sensors for different purposes and high frequency applications can be easily implemented. The integration possibility of passive electronic components, also in buried layers, as well as the integration of cooling channels and cavities enlarge the field of application. To reach a higher grade of miniaturization the standard LTCC process is enhanced with picosecond laser processing.
To connect electrical lines in different layers vias are necessary. The picosecond laser structuring technology enables a reduction of the via diameter of 50 µm (punched vias) to 30 µm and lower. Reaching a high resolution of lines with small line widths and small spaces is necessary to fulfill the often required high level of integration. Normally the fine line screen printing process with specialized plasma coated screens and screen printing pastes with high requirements regarding particle distribution is used. For buried lines the resolution can be increased more simply by using picosecond laser ablation in the green state. The line width can be reduced down to 20 µm in the green state which corresponds to around 17.5 µm after firing of the LTCC substrate. In contrast to fine line screen printing the laser ablation process can be applied to standard screen printing pastes of different material systems. After firing the picosecond laser ablation process offers line widths down to 13.5 µm with spaces down to 10.8 µm. The accuracy of 0.3 µm for post fired laser structuring of screen printed thick films is another outstanding advantage. Finally, the relatively high stacking tolerances of 10 µm and higher between the different layers of the LTCC substrate can be reduced to 2.5 µm and lower. Multilayered patterns with high requirements to the alignment like micro inductors are enabled by modifying the structuring process. This is called advanced sequential picosecond laser structuring process.
The picosecond laser structuring processes, which are established at the University of Ilmenau, can meet the demands of a high grade of miniaturization and an easy integration of the laser structuring processes itself in the manufacturing process of LTCC substrates at the same time.
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