BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be explained in greater detail on the basis of exemplary embodiments with reference to the drawings. In the figures:
FIG. 1: shows a sintered bushing in cross-section; and
FIG. 2: shows a cardiac pacemaker having a bushing according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The bushing shown in FIG. 1 has a flange 1, which includes an insulation body 4. A terminal pin 3 passes through the insulation body 4. Instead of one terminal pin, in multipolar bushings, which are not shown here, multiple terminal pins may also be provided, which preferably project through the insulation body 4 parallel to one another.
In addition, a filter body 5 may be provided, which acts as a capacitor between the flange 1 and the terminal pin 3 and in this way acts as a low-pass filter, because high-frequency interference is short-circuited using the filter body. For this purpose, the filter body has electrodes which are each alternately connected to the flange and to the terminal pin using an electrically conductive connection material, such as an electrically conductive thermoplastic or an electrically conductive (metal) solder.
FIG. 1 shows an exemplary bushing, in which a terminal pin 3 and an insulation body 4 as well as a flange 1 are bonded to one another by sintering. The insulation body comprises an insulating material, such as a glass ceramic or ceramic, in particular Al2O3. The glass ceramic or the ceramic of the insulation body 4 is bonded hermetically sealed to the terminal pin 3 and the flange 1 due to the sintering process, so that any solder for sealing is obsolete. The terminal pin 3 comprises metal and may be produced from drawn solid material. The flange 1 itself may also be sintered. In this case, the flange 1 and insulator 4 are provided as a pressed, injection molded, or otherwise molded green product before the sintering process which bonds these components to one another.
The bond resulting due to the sintering process during bonding of the components is friction-locked as a result. The sintering process is preferably performed in such way that physical or chemical reactions which have a favorable effect on the long-term stability and the hermetic seal of the bushing occur at the interface between the components, in particular at the interface between terminal pin 3 and insulation body 4 on one hand and the interface between insulation body 4 and flange 1 on the other hand. An advantage of this production process is that no further following processes are needed. An advantage of the bushing produced in this way is that it is particularly tight and stable for a long time.
Preparation of the Interfaces, for Example, by Coating or in Another Way, is Typically not necessary.
As indicated by dashed lines in FIG. 1, the bushing may optionally have a filter 5.
Finally, FIG. 2 shows an example of a cardiac pacemaker 20, whose metallic housing is already closed using a filter bushing of the type shown in FIG. 1. For the sake of simplicity, the typical header of a cardiac pacemaker, in which the terminal sockets for the electrode lines are located, is not shown in FIG. 2. The electrical contacts of these terminal sockets are electrically connected to the pins 3 of the filter bushing in the finished cardiac pacemaker. The filter bushing—more precisely its flange 1—is connected hermetically sealed to the housing 22 of the cardiac pacemaker 20, preferably by welding. Therefore, it is advantageous if the flange 1 of the filter bushing comprises the same material as the housing 22 of the cardiac pacemaker 20.
Patent Application
20080060834
