| 摘要 |
The present invention relates to the field of solid state capacitors, and in particular to capacitors that have an anode body formed of porous valve action material, such as tantalum, niobium or niobium monoxide. According to one aspect of the present invention, there is provided a method of forming capacitor anode bodies from valve action material comprising the steps of: providing a capacitor grade powder of the valve action material, charging the powder into moulding means, compacting the powder in the moulding means so as to shape the powder into an anode body shape, stabilising the body shape, for example by sintering of the material to form an inter-connected porous body, characterised in that the moulding process involves the use of lubrication means which is adapted to apply lubricant locally to lubricate the interface between an outside surface of the anode body and a moulding surface of the moulding means. By applying a lubricant directly to the parts of the mould and anode green that most require lubricant, it is possible considerably to reduce the amount of binder/lubricant that must be added to the valve action powder. In fact, in the case of tantalum, it has surprisingly been found that it is possible to avoid completely the need for an admixed binder/lubricant. This is thought to be because the compaction of the tantalum powder in the presence of an external lubricant provides sufficient structural integrity of the green to be manipulated and transported to a sintering station, without disintegrating. |
