METHOD FOR PRODUCING A METAL-CERAMIC SUBSTRATE AND FURNACE
The invention relates to a method for producing a metal-ceramic substrate and to a furnace suitable for carrying out the method. With the method, a metal-ceramic substrate with increased thermal and current conductivity can be obtained. The method comprises the steps of providing a stack containing a ceramic body, a metal foil, and a solder material in contact with the ceramic body and the metal foil, the solder material comprising a metal having a melting point of at least 700° C., a metal having a melting point of less than 700° C., and an active metal, and heating the stack, the stack passing through a heating zone for heating.
1 . A method for producing a metal-ceramic substrate comprising the steps of:
a) providing a stack containing
a1) a ceramic body,
a2) a metal foil, and
a3) a solder material in contact with the ceramic body and the metal foil, the solder material comprising:
(i) a metal having a melting point of at least 700° C.,
(ii) a metal having a melting point of less than 700° C., and
(iii) an active metal, and
b) heating the stack, the stack passing through a heating zone for heating.
2 . The method according to claim 1 , wherein the ceramic of the ceramic body is selected from the group consisting of aluminum nitride ceramics, silicon nitride ceramics and aluminum oxide ceramics.
3 . The method according to claim 1 , wherein the metal of the metal foil is copper.
4 . The method according to claim 1 , wherein the metal having a melting point of at least 700° C. is copper.
5 . The method according to claim 1 , wherein the metal having a melting point of less than 700° C. is selected from the group consisting of tin, bismuth, indium, gallium, zinc, antimony and magnesium.
6 . The method according to claim 1 , wherein the active metal is selected from the group consisting of hafnium, titanium, zirconium, niobium, tantalum, vanadium and cerium.
7 . The method according to claim 1 , wherein the proportion of silver is less than 3.0 percent by weight, relative to the total metal weight of the solder material.
8 . The method according to claim 1 , wherein a non-oxidizing atmosphere is present in the heating zone.
9 . The method according to claim 1 , wherein a nitrogen atmosphere is present in the heating zone.
10 . The method according to claim 1 , wherein the peak-temperature heating duration is no more than 30 min, wherein the peak-temperature heating duration refers to the time duration during which the stack is exposed to a temperature corresponding at least to the peak temperature −50° C.
11 . The method according to claim 1 , wherein the heating-up duration is no more than 60 min, wherein the heating-up duration denotes the time period which the stack requires in order to reach the peak temperature starting from a temperature of 100° C.
12 . A furnace having at least
(1) a heating zone,
(2) a carrier system, and
(3) a stack arranged on the carrier system and containing
a1) a ceramic body,
a2) a metal foil, and
a3) a solder material in contact with the ceramic body and the metal foil, the solder material comprising:
(i) a metal having a melting point of at least 700° C.,
(ii) a metal having a melting point of less than 700° C., and
(iii) an active metal,
wherein the heating zone and the carrier system are designed such that the position of the stack relative to the position of the heating zone can be changed in order to allow heating of the stack while it passes through the heating zone.