Recent Advances in Active Metal Brazing of Ceramics and Process

Abstract

Ceramic to metal joining has its potential applications in microelectronics packaging, metal-ceramic seals, vacuum tubes, sapphire metal windows, etc. But there are many limitations in joining this duo of materials that range from their structures, nature of bonding, physical properties to a complex phenomenon like wetting, spreading and adhesion. The current review discusses these critical issues from the aspects of thermodynamics, the role, and type of active elements, Ag-Cu-Ti brazing filler system and the reliability factors like residual stress, coefficient of thermal expansion, material reliability, pores and unbonded regions on the surface which affect the mechanical reliability of the joint.

High-Entropy Alloys for Micro- and Nanojoining Applications

“…Since metals are soft and malleable, for various functional applications, their joining is needed in semiconductors. There are various types of filler materials already available, such as Ag-Cu-Ti brazing system which is most suitable in metal-ceramic joining [7,14].…”

“…γ sv − γ sl − γ lv = 0 for minimum surface energy (high spreading) and S < 0 for poor wetting. Figure 4(b) gives the wetting angles of different metals at various temperatures [7].…”

“…The addition of several active elements can also contribute to various IMCs, Cu-Ti, Cu 3 Ti, Ti 3 SiC 2 , etc. Due to these brittle IMCs, the joint cannot be operated at high temperatures [6][7][8][9][10][11][12]. Therefore, the key factor to braze ceramics to metals is to look for new fillers for brazing where active elements (Ti, Zr, etc.)…”

“…(a) Schematic of filler wetting at the substrate and (b) contact angle of metals on cBN substrate. [the data in (b) is adapted from[7]]. …”

Joining of SiO2 glass and 316L stainless steel using Bi–Ag-based active solders

“…Many of such applications require joining of the SiO 2 glass and a metallic substrate. Various techniques such as brazing and soldering [5], mechanical [6], adhesive [7], anodic [8] and diffusion [9] bonding are utilized for joining dissimilar materials (e.g. metal/ ceramics and metal/glass joints).…”