Stress relief interlayer

The initial approach in this study was to demonstrate the use of metallic interlayers and/or coatings in the bonding procedure. For the first layer (intended for the metallurgical bonding of the ceramic), Ti and Cr were found to be the most promising metals. Here both coatings (by PVD, 1-10 0.m thick) and layers of foils (25 im thick) were used. The function of the second Ta layer of 25 im thickness was to suspend the diffusion of Ti between the foils. In all of the experiments the third layer of niobium of 2 mm thickness was applied for thermal residual stress relief. The multilayered joint microstructure is shown in Fig. lb [7]. 

Polyimides have been widely used in the advanced microelectronics industry such as passivation or stress-relief layers for high-density electronic packaging, interlayer dielectric layers for wafer-level semiconductor fabrication, or alignment layers for liquid crystals in advanced liquid crystal display devices (LCDs) owing to their outstanding thermal, mechanical and good insulation properties with low dielectric constant, good adhesion to common substrates and superior chemical... 

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