The Direct Bonding of Metals to Ceramics and Application in Electronics

Abstract

The direct bonding of metals to ceramics is possible utilizing a gas metal eutectic. The mechanism of direct bonding of copper foil to ceramics in a slightly oxidizing atmosphere is presented. It involves the formation of eutectic melt between copper and oxygen at a temperature slightly below the melting point of copper, which serves to bring the foil into intimate contact with the substrate. Metals to which technique is applicable include Cu, Fe, Ni, Co, Ag, Cr, Mo and Al. A brief review of other metal–ceramic bonding techniques is given for comparison.The process for fabricating direct bonded copper structures is given, and properties of the bond are discussed. The use of the directed bonding process in a number of electronic applications such as hybrid packages and power device heat sinks is indicated.

Characteristics of Active Metal Brazed Joint of Al2O3/Cu Applicable to Electric Vehicle

“…In the electric vehicles, ceramic-metal joints can be applicable to a large current terminal parts, electrical relays, DBC (Direct Bonded Copper) substrate, circuit boards for power devices, heat dissipation substrates for power modules, an ECU (Engine Control Unit) and so on [1]. Several techniques for ceramic-metal joining have been developed like brazing, diffusion bonding, soldering, eutectic bonding, adhesive bonding, and so on [2][3][4][5].…”

“…In the electric vehicles, ceramic-metal joints can be applicable to a large current terminal parts, electrical relays, DBC (Direct Bonded Copper) substrate, circuit boards for power devices, heat dissipation substrates for power modules, an ECU (Engine Control Unit) and so on [1]. Several techniques for ceramic-metal joining have been developed like brazing, diffusion bonding, soldering, eutectic bonding, adhesive bonding, and so on [2][3][4][5].Among these techniques an active brazing process is simple as well as economical compared to other processes because of direct bonding of ceramic to metal. The active metal brazing facilitates the bonding of ceramics and metals without melting the base materials, which makes easier to bond ceramics and metals, and it is characteristics of brazing and solid state bonding processes.…”

Microstructure–thermal properties of Cu/Al2O3 bilayer prepared by direct bonding

“…Table 1 contains a summary of the processing conditions used in previous studies. [4][5][6][7][8][9][10][11][12][13][14][15][16] Though many studies have been conducted on this subject, the thermal resistance of the Cu-Al 2 O 3 interface and its microstructure-thermal property relationship are not yet available.…”

“…The eutectic liquid wets the alumina well; an intimate bond between Cu and Al 2 O 3 could be formed through the assistance of the eutectic liquid. [4][5][6][7][8][9][10][11][12][13][14][15][16] The direct bonding process is thus also termed eutectic bonding. In the present study, different amounts of oxygen were introduced into copper through various preoxidation treatments at temperatures lower than 600 • C. The alumina substrate was then joined with the pre-oxidized copper at a temperature between the eutectic point (1065 • C) and the melting point of copper (1083 • C).…”

Long-term mechanical reliability of ceramic thick-film circuits and mechanical sensors under static load

“…Typical technologies for creating circuits on ceramics are thick-film, thin-film, low-temperature cofired ceramic (LTCC, a development of thick-film), high-temperature cofired ceramic (HTCC, mainly used for ceramic packages) and direct bonded copper (DBC) [1][2][3][4][5][6]. Available ceramic substrates include 96% thickfilm grade alumina (Al 2 O 3 with ca.…”