# US 10,485,099 B2 · Multilayer ceramic substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,485,099 B2 - Document ID: US10485099B2 - Status: Granted - Kind: B2 - Application number: 16/170,427 - Filed: 2018-10-25 - Published: 2019-02-28 - Granted: 2019-11-19 - Earliest claimed: 2016-04-28 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Takahiro Oka; Yoshitake Yamagami; Yuki Takemori; Kazuo Kishida; Hiromichi Kawakami - Web page: https://patentgrep.com/patent/US10485099B2 ## CPC - H05K 1/0271: {Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion} - H05K 3/4629: {laminating inorganic sheets comprising printed circuits, e.g. green ceramic sheets} - H05K 1/0306: {Inorganic insulating substrates, e.g. ceramic, glass} - H05K 3/285: {Permanent coating compositions} - H05K 3/46: Manufacturing multilayer circuits - H05K 3/4644: {by building the multilayer layer by layer, i.e. build-up multilayer circuits (making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602)} - H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)} - H05K 2201/0175: Inorganic, non-metallic layer, e.g. resist or dielectric for printed capacitor - H05K 2201/0195: Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure - H05K 2201/0269: Non-uniform distribution or concentration of particles - H05K 2201/068: wherein the coefficient of thermal expansion is important - H05K 2203/0278: Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive - H05K 2203/1131: Sintering, i.e. fusing of metal particles to achieve or improve electrical conductivity - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A multilayer ceramic substrate according to the present invention includes a plurality of base layers that are laminated containing a low-temperature co-fired ceramic material, a plurality of first constraint layers which contain a metal oxide not completely sintered at the sintering temperature of the low-temperature co-fired ceramic material and which are located between the base layers, and a protective layer which contains the metal oxide and which is in contact with an outermost base layer of the plurality of base layers in the lamination direction, and wherein X1>X2, where X1 is a content of the metal oxide in a surface section of the protective layer and X2 is a content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layer. ## Claims ### Claim 1 A multilayer ceramic substrate comprising: a plurality of base layers that are laminated containing a low-temperature co-fired ceramic material; a plurality of first constraint layers which contain a metal oxide that is not completely sintered at a sintering temperature of the low-temperature co-fired ceramic material and which are located between adjacent base layers of the plurality of laminated base layers; and a protective layer which contains the metal oxide and which is located outermost in a lamination direction of the plurality of laminated base layers and is in contact with an outermost base layer of the plurality of laminated base layers in the lamination direction, wherein X1>X2, where X1 is a first content of the metal oxide in a surface section of the protective layer and X2 is a second content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layer, and wherein the protective layer includes a second constraint sublayer in contact with the outermost base layer and a covering ceramic sublayer on the second constraint sublayer, and multilayer ceramic substrate further comprises a wiring conductor on the second constraint sublayer, the covering ceramic sublayer is located so as to cover a periphery of the wiring conductor on the second constraint sublayer, the covering ceramic sublayer contains the metal oxide, and a surface of the covering ceramic sublayer has a region having a metal oxide content higher than that of other regions of the covering ceramic sublayer. ### Claim 2 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein α11<α22, where α11 is a first thermal expansion coefficient of the surface section of the protective layer and α22 is a second thermal expansion coefficient of the boundary section of the protective layer. ### Claim 3 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the protective layer includes an outermost sublayer located outermost in the lamination direction, the second constraint sublayer and the outermost sublayer contain the metal oxide, and x1>x2 is satisfied, where x1 is a first content of the metal oxide in the outermost sublayer and x2 is a second content of the metal oxide in the second constraint sublayer. ### Claim 4 (depends on 3) The multilayer ceramic substrate according to claim 3, wherein α12<α23, where α12 is a first thermal expansion coefficient of the outermost sublayer and α23 is a second thermal expansion coefficient of the second constraint sublayer. ### Claim 5 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the covering ceramic sublayer contains a second low-temperature co-fired ceramic material. ### Claim 6 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the protective layer is composed of only the second constraint sublayer in contact with the outermost base layer. ### Claim 7 (depends on 6) The multilayer ceramic substrate according to claim 6, wherein the region of the second constraint sublayer has a thermal expansion coefficient less than that of the other regions of the second constraint sublayer. ### Claim 8 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the region of the covering ceramic sublayer has a thermal expansion coefficient less than that of the other regions of the covering ceramic sublayer. ### Claim 9 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein X1>X3>X2, where X3 is a third content of the metal oxide in a central section of the protective layer. ### Claim 10 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein α22<β, where α22 is a first thermal expansion coefficient of the boundary section of the protective layer, and β is a second thermal expansion coefficient of the base layer. ### Claim 11 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the metal oxide is at least one of alumina and silica. ### Claim 12 (depends on 1) The multilayer ceramic substrate according to claim 1, further comprising a second wiring conductor in or on at least one of the outermost base layer, the first constraint layers, and the protective layer. ### Claim 13 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the low-temperature co-fired ceramic material is selected from glass composite low-temperature co-fired ceramic materials, crystal glass low-temperature co-fired ceramic materials, and non-glass low-temperature co-fired ceramic materials. ### Claim 14 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the metal oxide includes at least one of aluminum, silica, zirconia, titania, silica, niobium pentoxide, tantalum pentoxide, and magnesia. ### Claim 15 (depends on 1) The multilayer ceramic substrate according to claim 1, wherein the first metal oxide contained in the first constraint layers and the second metal oxide contained in the protective layer are the same. ### Claim 16 A multilayer ceramic substrate comprising: a plurality of base layers that are laminated containing a low-temperature co-fired ceramic material; a plurality of first constraint layers which contain a metal oxide that is not completely sintered at a sintering temperature of the low-temperature co-fired ceramic material and which are located between adjacent base layers of the plurality of laminated base layers; and a protective layer which contains the metal oxide and which is located outermost in a lamination direction of the plurality of laminated base layers and is in contact with an outermost base layer of the plurality of laminated base layers in the lamination direction, wherein X1>X2, where X1 is a first content of the metal oxide in a surface section of the protective layer and X2 is a second content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layer, and wherein α11<α33<α22, where α11 is a first thermal expansion coefficient of the surface section of the protective layer, α22 is a second thermal expansion coefficient of the boundary section of the protective layer, and α33 is a third thermal expansion coefficient of the central section of the protective layer. ### Claim 17 A multilayer ceramic substrate comprising: a plurality of base layers that are laminated containing a low-temperature co-fired ceramic material; a plurality of first constraint layers which contain a metal oxide that is not completely sintered at a sintering temperature of the low-temperature co-fired ceramic material and which are located between adjacent base layers of the plurality of laminated base layers; and a protective layer which contains the metal oxide and which is located outermost in a lamination direction of the plurality of laminated base layers and is in contact with an outermost base layer of the plurality of laminated base layers in the lamination direction, wherein X1>X2, where X1 is a first content of the metal oxide in a surface section of the protective layer and X2 is a second content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layer, and wherein X2>Y, where Y is a third content of the metal oxide in the base layer.