US 5,476,728 AGranted

Composite multilayer parts

AssigneeTDK Corporation

InventorsAtsuyuki Nakano, Satoshi Saito, Takeshi Nomura

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Abstract

Non-magnetic ferrite composition used in the composite multilayer part of the invention is based on ferrite containing Fe.sub.2 O.sub.3 and CuO and/or ZnO and further contains 1 to 30% by weight of four oxide components of MgO, BaO, SiO.sub.2, and B.sub.2 O.sub.3 or five or six oxide components including the four oxide components plus at least one of SnO.sub.2 and CaO. Since the use of this non-magnetic ferrite minimizes the difference in coefficient of linear expansion between different materials used, the non-magnetic ferrite, when applied to composite multilayer parts such as shielded multilayer chip inductors, shielded multilayer transformers, and multilayer LC composite parts, prevents occurrence of cracks in the interior and avoids a lowering of circuit resistance due to precipitation of CuO, ZnO or the like at the interface between different materials. There result composite multilayer parts with improved characteristics.

Claims17

Dependent claims

A sintered composite multilayer part comprising a magnetic material layer containing magnetic ferrite, a non-magnetic insulator layer, and a conductor layer, said part having an inductor built therein,

said non-magnetic insulating layer being formed from a non-magnetic ferrite composition comprising a non-magnetic ferrite base component and an added oxide component,
said non-magnetic ferrite base component consisting of an oxide composition selected from the group consisting of
(a) an oxide composition consisting of iron oxide, copper oxide and zinc oxide,
(b) an oxide composition consisting of iron oxide and copper oxide, and
(c) an oxide composition consisting of iron oxide and zinc oxide,
said oxides in each of said oxide compositions (a), (b) and (c) comprising 100 mol % of said oxide composition,
said added oxide component being selected from the group consisting of
(i) a four oxide component consisting of magnesium oxide, barium oxide, silicon oxide and boron oxide,
(ii) a five oxide component consisting of the aforesaid four oxide component plus a fifth oxide selected from the group consisting of tin oxide and calcium oxide, and
(iii) a six oxide component consisting of the aforesaid four oxide component plus tin oxide and calcium oxide,
with the proviso that the added oxide component comprises 0.25 to 8% by weight of MgO, 0.4 to 9% by weight of BaO, 0.25 to 7% by weight of SiO.sub.2, 0.1 to 3% by weight of B.sub.2 O.sub.3, 0 to 0.7% by weight of SnO.sub.2, and 0 to 8% by weight of CaO, the total amount added being 1 to 30% by weight based on the non-magnetic ferrite base component.

8 more elements

Dependencies are inferred from the claim text.