Customized LTCC multi-layer for reliable use at high temperatures

LTCC has proven its superior performance in many applications, comprising high temperature automotive as well as high reliability medical and high frequency communications applications. Another application area is the production of packages for micro mechanical electrical systems (MEMS).

LTCC multi-layer substrate is manufactured by co-firing ceramics green sheet and circuit layer under 1000 ° C. This substrate is suitable for high frequency application, because low resistivity material, silver can be used to reduce conductor loss and ceramics characteristics is stable even under severe conditions. High precision dimensions and cavity structure by highly controlled shrinkage spread their applications to the MEMS field.

Screen printing process has been applied for circuit pattern metalizing and realized line/space = 60/60 µm level in mass production. With the demands of miniaturization and multifunction, fine patterning technology is necessary. Recent development of nano technology is making ink-jet patterning with nano metal particle dispersed ink possible. With the control of the volume and landing position of each droplet, fine patterning is realized.

Ink-jet printing with nano silver particle formed pattern containing the line/ space = 30/30 µm fine line on the LTCC green sheet. After Stacking and co-firing, multi-layer substrate is realized. For high density circuit, small diameter vias to connect each layer are suitable for fine line. Though conventional via diameter was100µm, we developed 30µm micro-vias. Reliability and high frequency characteristics evaluation of the substrate with ink-jet patterning and micro via showed equivalent performance with conventional thick film one.

On the surface KOA also realized 20 µm pitch finer pattern with their original thin film technology to downsize increasingly. Its adhesive force to the substrate and reliability was enough for surface mounting.