Metal/ceramic circuit board

#1. Field of the Invention

#The present invention generally relates to a metal/ceramic circuit board having a ceramic substrate and a metal circuit plate which is formed on the ceramic substrate directly or via a brazing filler metal or the like. More specifically, the invention relates to a metal/ceramic circuit board on which parts, such as semiconductor parts, are mounted and which is used for a power module or a Peltier element module.

#2. Description of the Prior Art

#The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiments of the invention. However, the drawings are not intended to imply limitation of the invention to a specific embodiment, but are for explanation and understanding only.

#In the drawings:

#FIGS. 1A through 1C are sectional views showing steps of producing a metal/ceramic circuit board according to the present invention;

#Referring now to the accompanying drawings, the preferred embodiment of a metal/ceramic circuit board according to the present invention will be described below.

#The preferred embodiment of a metal/ceramic circuit board according to the present invention is produced by using the direct bonding method for arranging a metal plate on a ceramic substrate so as to allow the metal plate to directly contact the ceramic substrate and for heating the metal plate and the ceramic substrate in an inert gas to bond the ceramic substrate and the metal plate to each other, or by using the brazing and soldering method for arranging a metal plate on a ceramic substrate via a brazing filler metal containing an active metal, such as Ti, Zr or Hf, to heat them in a vacuum to bond the ceramic substrate and the metal plate to each other. These methods are preferred when the metal plate is a copper metal. In addition, a method for brazing and soldering a metal plate to a ceramic substrate via Al—Si or Al—Si—Ti brazing filler metals containing Al, or a method for bonding a metal plate directly to a ceramic substrate by the molten metal bonding method may be used. These methods are preferred when the metal plate is an Al plate.

#In order to pattern a metal plate, such as a copper plate, which is bonded to a ceramic substrate for a circuit or radiating plate, in a predetermined shape, an etching resist is applied on the surface of the metal plate in a pattern shape (or the surface of the metal plate is masked with an etching resist in a pattern shape), to etch the metal plate in a predetermined pattern. Alternatively, a method for bonding a metal plate to a ceramic substrate after forming a metal plate having a predetermined pattern shape by press working or etching may be used. The etching method is preferred in view of the dimensional precision or positional precision of the pattern. However, the above described methods may be chosen in view of the required precision and costs.