Patent Description:
An insulating ceramic substrate may be used as a circuit substrate mounted on an electronic device. The following techniques as described in Patent Literature <NUM> are known as a method for manufacturing such a circuit substrate. In other words, a composite substrate is formed by joining metal layers to both surfaces of a ceramic substrate having a scribe line formed on its surface. Then, the metal layer on the surface of the composite substrate is processed into a circuit pattern by etching. Subsequently, the composite substrate is divided along the scribe line and a plurality of circuit substrates are manufactured.

Meanwhile, mark formation techniques are known so that a worker and an automatic assembly machine recognize product information in manufacturing a circuit substrate and a package including the circuit substrate. For example, Patent Literature <NUM> proposes a technique with which a specific part of a sintered body of ceramics is given a color tone different from that of another part to serve as a marking portion. Patent Literature <NUM> proposes using a barcode-shaped marker pattern.

Further ceramic substrates to be used as circuit boards for electronic devices are described in Patent Literatures <NUM> to <NUM>.

After a circuit or the like is formed, a ceramic substrate is processed by cutting or the like to become a product or a component. With electronic devices further improving in terms of performance, it is required to sufficiently enhance the processing accuracy at the time of such circuit formation and processing. For the processing accuracy enhancement, the ceramic substrate needs to be aligned with high accuracy in each process. However, the barcode-shaped marker pattern or the like is usually different for each sheet and cannot be easily used for alignment.

In this regard, the present invention provides a composite substrate according to claim <NUM>, capable of enhancing alignment accuracy and a method for manufacturing the same, according to claim <NUM>. In addition, the present disclosure provides a composite substrate in which the positional accuracy of metal and ceramic substrates is excellent and a method for manufacturing the same. In addition, the present disclosure provides a circuit substrate excellent in alignment accuracy when a divided substrate is obtained by division and a method for manufacturing the same.

A composite substrate according to one aspect of the present invention comprises a ceramic substrate and a metal sheet, wherein the metal sheet is joined to the ceramic substrate so as to cover the main surface; wherein the ceramic substrate includes a main surface having a plurality of sections divided by division lines in the form of scribe lines and an alignment mark; wherein the main surface has at least one of the scribe lines closer to a center of the main surface than the alignment mark; and wherein the alignment mark is provided in an end portion delimited by an outer edge of the main surface and the scribe line that is positioned farthest from the center of the main surface; wherein the metal sheet has at least one selected from a group consisting of a notch portion and a through hole; and wherein the alignment mark is exposed from the notch portion or the through hole.

Such a composite substrate has the alignment mark on the main surface, and thus the alignment accuracy in using the composite substrate can be improved. Further, the main surface has at least one of the scribe lines closer to the center than the alignment mark, and thus the part closer to the center than the alignment mark can be effectively used for various components and products. It should be noted that the "scribe line closer to the center than the alignment mark" in the present disclosure means a scribe line intersecting with the line segment connecting the alignment mark and the center of the surface of the ceramic substrate.

The alignment mark may have at least one selected from a group consisting of an intersection and a rotationally symmetric shape. The alignment accuracy can be further improved with the alignment mark having such a shape.

In the composite substrate, an identification mark different in shape from the alignment mark may be provided on the main surface and at least one of the scribe lines may be provided closer to the center of the main surface than the identification mark. By having the identification mark, traceability can be improved and quality management can be performed efficiently. Further, the scribe line is provided closer to the center than the identification mark, and thus the part closer to the center than the identification mark can be effectively used for various components and products. It should be noted that the "scribe line closer to the center than the identification mark" in the present disclosure means a scribe line intersecting with the line segment connecting the identification mark and the center of the surface of the ceramic substrate.

In the composite substrate, the alignment mark may be two or more in number. In this manner, the alignment accuracy can be improved even in a case where a plurality of ceramic substrates having different sizes or shapes are aligned.

The alignment mark is provided in an end portion divided by an outer edge of the main surface and the scribe line. In this manner, the part of the composite substrate that cannot be effectively used as a product or a component can be reduced and the manufacturing costs of the composite substrate and a component and a product using the ceramic substrate can be reduced.

The composite substrate according to the present invention includes: the ceramic substrate as described above; and a metal sheet joined to the ceramic substrate so as to cover the main surface. Thus, alignment during joining can be performed with high accuracy. Accordingly, the positional accuracy of the metal and ceramic substrates is excellent.

The metal sheet has at least one selected from a group consisting of a notch portion and a through hole, and the alignment mark is exposed from the notch portion or the through hole. In this manner, the accuracy of alignment can be improved during, for example, metal sheet joining, resist application, and circuit formation.

A circuit substrate using the composite substrate according to the present invention includes: the ceramic substrate as described above; and a conductor portion provided on the main surface so as to be independent for each section defined by the scribe lines, in which the alignment mark is exposed on the main surface. By having such an alignment mark, the alignment accuracy at a time when, for example, a divided substrate is obtained by division can be improved.

A composite substrate manufacturing method according to another aspect of the present invention includes: a step of obtaining a ceramic base material having an alignment mark on a main surface; a step of obtaining a ceramic substrate by irradiating the main surface with laser light to form scribe lines dividing the main surface into a plurality of sections; and a step of obtaining the composite substrate by joining a metal sheet to the ceramic substrate so as to cover the main surface of the ceramic substrate. The main surface of the ceramic substrate has at least one of the scribe lines closer to a center of the main surface than the alignment mark. The alignment mark is provided in an end portion delimited by an outer edge of the main surface and the scribe line that is positioned farthest from the center of the main surface, and the metal sheet is joined in the step of obtaining the composite substrate such that the alignment mark is exposed from at least one selected from a group consisting of a notch portion and a through hole of the metal sheet.

In this manufacturing method, the ceramic base material having the alignment mark on the main surface is used, and thus the alignment accuracy in forming the scribe lines can be improved. In addition, the ceramic substrate has the alignment mark on the main surface, and thus the alignment accuracy in using the ceramic substrate can be improved. In addition, the ceramic substrate where the scribe lines are formed has at least one of the scribe lines closer to the center than the alignment mark, and thus the part closer to the center than the alignment mark can be effectively used for various components and products.

In this manufacturing method, the ceramic substrate having the alignment mark is used, and thus the alignment accuracy of the ceramic and metal sheets can be enhanced. Accordingly, a composite substrate in which the positional accuracy of ceramic and metal sheets is excellent can be manufactured.

The metal sheet is joined in the step of obtaining the composite substrate such that the alignment mark is exposed from at least one selected from a group consisting of a notch portion and a through hole of the metal sheet. By using the alignment mark exposed from the notch portion or the through hole, the accuracy of alignment can be improved during, for example, metal sheet joining, resist application to the metal sheet, and circuit formation.

A circuit substrate manufacturing method according to one aspect of the present disclosure includes a step of obtaining a circuit substrate where the alignment mark on the main surface of the ceramic substrate is exposed by removing a part of the metal sheet in the composite substrate obtained by the manufacturing method and forming an independent conductor portion for each section defined by the scribe lines. The alignment mark is exposed on the main surface of the ceramic substrate in the circuit substrate obtained by this manufacturing method. Accordingly, the alignment accuracy at a time when, for example, a divided substrate is obtained by division can be improved.

According to the present disclosure, a composite substrate capable of enhancing alignment accuracy and a method for manufacturing the same are provided. In addition, the present disclosure is capable of providing a composite substrate in which the positional accuracy of metal and ceramic substrates is excellent and a method for manufacturing the same. In addition, the present disclosure is capable of providing a circuit substrate excellent in alignment accuracy when a divided substrate is obtained by division and a method for manufacturing the same.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings as the case may be. However, the following embodiment is an example for describing the present disclosure and is not intended to limit the present disclosure to the following content. In the description, the same reference numerals are used for the same elements or elements identical in terms of function with redundant description omitted as the case may be. In addition, the positional relationships including up, down, left, and right are based on those illustrated in the drawings unless otherwise noted. Further, the dimensional ratio of each element is not limited to the illustrated ratio.

<FIG> is a perspective view of a ceramic substrate to be used in a composite substrate according to an embodiment of the present invention. A ceramic substrate <NUM> of <FIG> has a flat plate shape. A main surface 100A (front surface 101A) of the ceramic substrate <NUM> is divided into a plurality of sections by scribe lines. The main surface 100A is provided with a plurality of scribe lines L1 and a plurality of scribe lines L2 as the scribe lines. The plurality of scribe lines L1 extend along a first direction and are arranged at equal intervals. The plurality of scribe lines L2 extend along a second direction orthogonal to the first direction and are arranged at equal intervals. The scribe line L1 and the scribe line L2 are orthogonal to each other.

The scribe lines L1 and L2 may, for example, be configured by arranging a plurality of recesses in a straight line or have grooves formed in a linear shape. Specifically, the scribe lines L1 and L2 may be formed by laser light. Examples of a laser source include a carbonic acid gas laser and a YAG laser. The scribe line can be formed by intermittently emitting laser light from such a laser source. It should be noted that the scribe lines L1 and L2 may not be arranged at equal intervals and are not limited to those orthogonal to each other. In addition, the scribe lines L1 and L2 may be curved or bent without being straight.

The ceramic substrate <NUM> has a plurality of sections <NUM> defined by the scribe lines L1 and L2. The ceramic substrate <NUM> has alignment marks <NUM> and identification marks <NUM> in an end portion <NUM> of the main surface 100A. The end portion <NUM> is an outer peripheral region divided by an outer edge <NUM> of the main surface 100A and one or both of the scribe line L1 and the scribe line L2 positioned farthest from a center C of the main surface 100A. In a case where the ceramic substrate <NUM> is for a circuit substrate, the region that surrounds the plurality of sections <NUM> where conductor portions are formed corresponds to the end portion <NUM>.

The main surface 100A has at least one scribe line L1 and at least one scribe line L2 closer to the center C than the alignment mark <NUM> and the identification mark <NUM>. In other words, the main surface 100A has the scribe lines L1 and L2 intersecting with respective line segments connecting the center C to the alignment marks <NUM> and the identification marks <NUM>. By cutting along the scribe lines L1 and L2, the part that is closer to the center C than the alignment marks <NUM> and the identification marks <NUM> can be effectively used for various components and products. The main surface 100A has at least one section <NUM> including the center C.

At the four corners of the main surface 100A of the ceramic substrate <NUM>, the four alignment marks <NUM> and the four identification marks <NUM> are provided so as to be adjacent to each other. By having the plurality of alignment marks in this manner, the accuracy of alignment can be further enhanced.

A main surface 100B (back surface 100B) of the ceramic substrate <NUM> may also have the scribe lines L1 and L2, the alignment marks <NUM>, and the identification marks <NUM> as in the case of the main surface 100A. However, it is not essential for the main surface 100B to have all of these. For example, the main surface 100B may have at least one of the scribe lines L1 and L2, the alignment marks <NUM>, and the identification marks <NUM> or may not have any of the scribe lines L1 and L2, the alignment marks <NUM>, and the identification marks <NUM>.

<FIG> is a partially enlarged view illustrating the part where one of the four alignment marks <NUM> in the end portion <NUM> of the main surface 100A of the ceramic substrate <NUM> and one of the four identification marks <NUM> in the end portion <NUM> of the main surface 100A of the ceramic substrate <NUM> are provided.

The alignment mark <NUM> has a cross shape in a plan view. The alignment mark <NUM> is configured to be detectable by, for example, an imaging device (e.g. camera or video). The alignment mark <NUM> has an intersection where two or more line segments intersect, and thus the reference for alignment becomes clear and the accuracy of alignment can be further enhanced. From a similar viewpoint, the alignment mark <NUM> may have a rotationally symmetric shape in a plan view. In a case where the alignment mark <NUM> has a rotationally symmetric shape, the accuracy of alignment can be further enhanced by the center of rotation serving as a reference for alignment. In a plan view, the alignment mark <NUM> may be, for example, circular, triangular, or quadrangular.

In a case where the alignment mark <NUM> is circular, the diameter of the alignment mark <NUM> may be <NUM> to <NUM>. In a case where the alignment mark <NUM> has a polygonal outer shape, the diameter at a time when the circumscribed circle is drawn may be <NUM> to <NUM>. With the alignment mark <NUM> having such a size, the effectively usable part of the ceramic substrate <NUM> can be made sufficiently large and the accuracy of imaging device-based detection can be sufficiently enhanced. In a case where the alignment mark <NUM> is configured by a recessed portion having a depth (such as a groove and a hole), the depth may be <NUM> to <NUM>. However, it is not essential for the alignment mark <NUM> to have a depth and the alignment mark <NUM> may be a two-dimensional pattern.

The identification mark <NUM> is a two-dimensional code and is configured by a plurality of recessed portions 12a being arranged in accordance with a predetermined rule. The identification mark <NUM> may be, for example, a two-dimensional barcode such as a QR code (registered trademark) or may be a one-dimensional code such as a barcode. In addition, the identification mark <NUM> may be a three-dimensional code using, for example, information on the depth of the recessed portion 12a as well. In addition, the identification mark <NUM> is not limited to that configured by the recessed portion 12a. For example, the identification mark <NUM> may be configured by a two-dimensional pattern or may be a combination of the recessed portion 12a and a pattern.

The identification mark <NUM> is provided for the ceramic substrate <NUM> to be identified. The identification mark <NUM> may be a code associated with some information. Examples of the information include information on lots, manufacturing histories, product types, uses, qualities, and manufacturing conditions. By using the identification mark <NUM>, manufacturing conditions can be optimized and improvements can be achieved in terms of quality, the accuracy of process management, traceability, and so on.

The identification mark <NUM> may be, for example, at least one of the following information (a) to (d) that has been coded.

The identification mark <NUM> is also configured to be detectable by, for example, an imaging device (e.g. camera or video). The imaging device may have, for example, an information processing unit collating a captured image with pre-recorded information and outputting information based on the collation result.

The depth of the recessed portion 12a constituting the identification mark <NUM> may be <NUM> to <NUM> or <NUM> to <NUM>. As for the size of the identification mark <NUM>, the length of each side may be approximately <NUM> to <NUM> in a plan view. With the identification mark <NUM> having such a size, the effectively usable part of the ceramic substrate <NUM> can be made sufficiently large and the accuracy of imaging device-based detection can be sufficiently enhanced.

The positions and numbers of the alignment marks <NUM> and the identification marks <NUM> are not limited to those described above. The alignment mark <NUM> and the identification mark <NUM> may be provided so as to be adjacent to each other in the end portion <NUM> as in the presently discussed ceramic substrate or may be provided apart from each other. In addition, the numbers of the alignment marks <NUM> and the identification marks <NUM> may be different from each other without being equal to each other.

<FIG> is a plan view of a ceramic substrate to be used in the composite substrate according to another embodiment. A ceramic substrate <NUM> of <FIG> is different from the ceramic substrate <NUM> illustrated in <FIG> and <FIG> in the number, positions, and shape of alignment marks. The ceramic substrate <NUM> is provided with two circular alignment marks 11A in the end portions <NUM> of the main surface 101A. The two alignment marks 11A are respectively provided near the middle in the up-down direction of <FIG> in the left and right end portions <NUM> of <FIG>. The configuration of the ceramic substrate <NUM> other than the alignment mark 11A may be identical to that of the ceramic substrate <NUM>.

<FIG> is a plan view of a ceramic substrate to be used in the composite substrate according to yet another embodiment. A ceramic substrate <NUM> of <FIG> is different from the ceramic substrate <NUM> illustrated in <FIG> and <FIG> in the numbers and positions of alignment and identification marks. In addition, the ceramic substrate <NUM> of <FIG> is different from the ceramic substrate <NUM> illustrated in <FIG> and <FIG> in that scribe lines L3 and L4 do not extend to the outer edge of a main surface 102A. In the end portion <NUM> of the main surface 102A of the ceramic substrate <NUM>, the alignment marks <NUM> are respectively provided near two corner portions diagonal to each other. In addition, one identification mark <NUM> is provided near one of the alignment marks <NUM>.

The ceramic substrates <NUM>, <NUM>, and <NUM> have the alignment marks <NUM> and 11A on the main surfaces 100A, 101A, and 102A, and thus the alignment accuracy in processing the ceramic substrates <NUM>, <NUM>, and <NUM> can be improved. As a result, defective product generation can be suppressed and damage to the identification mark <NUM> during laser processing can be suppressed. The alignment marks <NUM> and 11A and the identification mark <NUM> are provided in the end portion <NUM>, and thus the part inside the end portion <NUM> can be used for various components and products. In this manner, most of the ceramic substrates <NUM>, <NUM>, and <NUM> can be effectively used and the manufacturing costs of products and components using the ceramic substrates <NUM>, <NUM>, and <NUM> can be reduced. In addition, the ceramic substrates <NUM>, <NUM>, and <NUM> have the identification mark <NUM> in the end portion <NUM>, and thus traceability can be improved and quality management can be efficiently performed.

The ceramic substrate of the present disclosure is not limited to the ceramic substrates <NUM>, <NUM>, and <NUM> described above. For example, the alignment mark does not have to be two or more in number and may be one in number. However, the accuracy of alignment can be sufficiently enhanced by having two or more alignment marks. In addition, the accuracy of alignment can be further enhanced by two or more alignment marks being provided apart from each other in the end portion of the main surface. In a case where the main surface has, for example, a rectangular outer shape, the alignment marks may be provided in two corner portions diagonal to each other or may be provided in the four corner portions.

Each of the ceramic substrates described above has the alignment mark <NUM> (11A) and the identification mark <NUM> in the end portion <NUM> divided by the outer edge <NUM> of the main surface and at least one of the scribe line L1 and the scribe line L2. However, the present disclosure is not limited thereto and the alignment mark or the identification mark may be provided at a position other than the end portion <NUM>. In addition, the ceramic substrate may lack the identification mark. The ceramic substrate can be effectively used while enhancing the accuracy of alignment insofar as a section (scribe line) is provided closer to the center C than the alignment mark <NUM>.

<FIG> is a perspective view of an intermediate composite substrate obtained during the manufacturing of a composite substrate according to an embodiment. A composite substrate <NUM> includes a pair of metal sheets <NUM> disposed so as to face each other and the ceramic substrate <NUM> between the pair of metal sheets <NUM>. The pair of metal sheets <NUM> are joined to the ceramic substrate <NUM> so as to cover the main surface 100A and the main surface 100B of the ceramic substrate <NUM>. Examples of the metal sheet <NUM> include a copper plate. The shapes and sizes of the ceramic substrate <NUM> and the metal sheet <NUM> may be identical to or different from each other. The metal sheet <NUM> and the ceramic substrate <NUM> may be joined by, for example, a brazing material.

The composite substrate <NUM> includes the ceramic substrate <NUM>, and thus the alignment at a time of joining can be performed with ease. In addition, the composite substrate <NUM> includes the ceramic substrate <NUM> capable of enhancing the accuracy of alignment, and thus the positional accuracy of the ceramic substrate <NUM> and the metal sheet <NUM> is excellent.

<FIG> is a perspective view of a composite substrate according to another embodiment. A composite substrate <NUM> includes a metal sheet <NUM> and the metal sheet <NUM> disposed so as to face each other and the ceramic substrate <NUM> between the metal sheets <NUM> and <NUM>. The metal sheet <NUM> is joined to the ceramic substrate <NUM> so as to cover the main surface 102A of the ceramic substrate <NUM>. The metal sheet <NUM> is joined to the ceramic substrate <NUM> so as to cover the main surface on the side opposite to the main surface 102A. The metal sheets <NUM> and <NUM> and the ceramic substrate <NUM> may be joined by, for example, a brazing material.

The metal sheet <NUM> has two notch portions <NUM>. The notch portion <NUM> is formed at a part corresponding to the position of the alignment mark <NUM> of the ceramic substrate <NUM>. Accordingly, the alignment mark <NUM> and the identification mark <NUM> are exposed from one notch portion <NUM> and the alignment mark <NUM> is exposed from the other notch portion <NUM> (not illustrated). By having the notch portion <NUM> where the alignment mark <NUM> is exposed in this manner, the accuracy of alignment can be improved during, for example, joining between the metal sheet <NUM> and the ceramic substrate <NUM>, resist application to the metal sheet <NUM>, and circuit formation. In addition, the traceability of the composite substrate <NUM> can be improved by exposing the identification mark <NUM> from the notch portion <NUM>.

Although only one metal sheet <NUM> has the notch portion <NUM> in the composite substrate <NUM>, both metal sheets may be provided with the notch portion <NUM> in a case where the alignment mark <NUM> is provided on both main surfaces of the ceramic substrate. In addition, the shape, number, and positions of the notch portions <NUM> may be appropriately adjusted in accordance with the shape, number, and positions of the alignment marks <NUM>. In addition, a metal sheet where the notch portion <NUM> is replaced with a through hole and the alignment mark <NUM> or the alignment mark <NUM> and the identification mark <NUM> are exposed from the through hole may be provided.

The composite substrate of the present disclosure is not limited to that described above. For example, the composite substrate of the present disclosure may include the ceramic substrate <NUM> instead of the ceramic substrates <NUM> and <NUM> or may include a ceramic substrate different from the ceramic substrates. In one example of the composite substrate, a ceramic substrate is made of aluminum nitride or silicon nitride and a metal sheet is made of aluminum.

<FIG> is a perspective view of a circuit substrate according to an embodiment. A circuit substrate <NUM> includes the ceramic substrate <NUM> and conductor portions <NUM> disposed so as to face each other with the ceramic substrate <NUM> interposed therebetween. The conductor portions <NUM> are independently provided on the main surface 100A and the main surface 100B for each section <NUM>. In other words, each section <NUM> is provided with the pair of conductor portions <NUM> disposed so as to face each other. The alignment mark <NUM> and the identification mark <NUM> are exposed in the end portion <NUM> of the main surface 100A of the ceramic substrate <NUM>.

The circuit substrate <NUM> is cut along the scribe lines L1 and L2 and divided into a plurality of divided substrates. As for the circuit substrate <NUM>, the alignment mark <NUM> is exposed on the main surface 100A of the ceramic substrate <NUM>. Accordingly, the accuracy of alignment can be improved during, for example, division. In addition, the circuit substrate <NUM> uses the ceramic substrate <NUM>, the ratio of the effectively usable part of the ceramic substrate <NUM> to the ceramic substrate <NUM> is high, and thus the circuit substrate <NUM> and the divided substrate can be manufactured at a low manufacturing cost. The divided substrate is used as a component of, for example, a power module. An electronic component or the like is mounted on the conductor portion <NUM> of the divided substrate.

The circuit substrate of the present disclosure is not limited to that described above. For example, the circuit substrate of the present disclosure may include the ceramic substrate <NUM> or the ceramic substrate <NUM> instead of the ceramic substrate <NUM> or may include a ceramic substrate different from the ceramic substrates. In one example of the circuit substrate, a ceramic substrate is made of aluminum nitride or silicon nitride and a conductor portion is made of copper or aluminum.

A method for manufacturing the ceramic substrate <NUM> will be described as a ceramic substrate manufacturing method according to an embodiment. The method for manufacturing the ceramic substrate <NUM> has a step of obtaining a ceramic base material having an alignment mark on its main surface and a step of obtaining the ceramic substrate <NUM> by irradiating the main surface of the base material with laser light to form the scribe lines L1 and L2 dividing the main surface into a plurality of sections.

<FIG> is a plan view illustrating an example of the ceramic base material. A ceramic base material <NUM> can be manufactured by the following procedure. First, a green sheet is obtained by molding slurry containing, for example, inorganic compound powder, a binder resin, a sintering aid, a plasticizer, a dispersant, and a solvent.

Examples of the inorganic compound include silicon nitride (Si<NUM>N<NUM>), aluminum nitride (AlN), silicon carbide, and aluminum oxide. Examples of the sintering aid include a rare earth metal, an alkaline earth metal, a metal oxide, a fluoride, a chloride, a nitrate, and a sulfate. Each of these may be used alone or two or more of these may be used in combination. By using the sintering aid, the sintering of the inorganic compound powder can be promoted. Examples of the binder resin include methyl cellulose, ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, and a (meth)acrylic resin.

Examples of the plasticizer include phthalic acid-based plasticizers such as purified glycerin, glycerin triolate, diethylene glycol, and di-n-butyl phthalate and dibasic acid-based plasticizers such as di-<NUM>-ethylhexyl sebacate. Examples of the dispersant include poly(meth)acrylates and (meth)acrylic acid-maleate copolymers. Examples of the solvent include organic solvents such as ethanol and toluene.

Examples of the slurry molding method include a doctor blade method and an extrusion molding method. Recessed portions constituting alignment and identification marks are formed by irradiating the main surface of the molded green sheet with laser light. An infrared laser, a visible light laser, an ultraviolet laser, or the like may be used for the formation of the recessed portions.

Next, the ceramic base material <NUM> is obtained by degreasing and sintering the green sheet with the recessed portions formed on the main surface. The degreasing may be performed by, for example, performing heating for <NUM> to <NUM> hours at <NUM> to <NUM>. As a result, the residual amount of the organic matter (carbon) can be reduced while suppressing the oxidation and deterioration of the inorganic compound. The sintering is performed by performing heating to <NUM> to <NUM> in an atmosphere of a non-oxidizing gas such as nitrogen, argon, ammonia, and hydrogen. As a result, the base material <NUM> can be obtained.

With an alignment mark provided in the green sheet stage, alignment can be performed with high accuracy even in the degreasing and sintering step. In addition, with an identification mark provided together with an alignment mark, traceability can be ensured up to the green sheet stage. However, it is not essential to provide the alignment and identification marks in the green sheet stage and at least one of the marks may be provided after, for example, the base material <NUM> is prepared.

The degreasing and sintering described above may be performed with a plurality of green sheets laminated. Green sheets having alignment marks can be laminated with high positional accuracy. In a case where the degreasing and sintering are performed after lamination, a mold release layer using a mold release agent may be provided between the green sheets so that the base material is smoothly separated after firing. Boron nitride (BN) and so on can be used as the mold release agent. The mold release layer may be formed by, for example, applying slurry of boron nitride powder by a method such as spraying, brushing, roll coating, and screen printing. The positional accuracy of the mold release layer can also be improved by using an alignment mark here. <NUM> to <NUM> green sheets, <NUM> to <NUM> green sheets, and so on may be laminated from the viewpoint of allowing degreasing to proceed sufficiently while efficiently mass-producing ceramic substrates.

In this manner, the ceramic base material <NUM> having the alignment mark <NUM> on its main surface can be obtained. Usually, green sheets do not shrink uniformly during firing. Accordingly, the obtained base material <NUM> may be cut along a cutting line CL1 of <FIG> and the outer edge portion may be cut off. In this manner, the dimensional accuracy of the ceramic substrate can be improved. Further, the dimensions of the ceramic base material can be controlled with high accuracy by performing alignment using the alignment mark <NUM> during the cutting. The base material <NUM> can be cut by laser light.

Before, after, or simultaneously with the cutting of the base material <NUM>, one main surface of the base material <NUM> and, if necessary, the other main surface of the base material <NUM> are irradiated with laser light. Scribe lines serving as the scribe lines L1 and L2 are formed as a result. Also at this time, the positional accuracy of the scribe lines L1 and L2 can be enhanced by performing alignment using the alignment mark <NUM>. As a result, accidentally damaging the identification mark <NUM> can be suppressed sufficiently. The scribe lines L1 and L2 serve as cutting lines when the circuit substrate <NUM> is divided in the subsequent step. Examples of a laser source for the cutting and scribe line formation include a carbonic acid gas laser and a YAG laser.

The ceramic substrate <NUM> as illustrated in <FIG> and <FIG> is obtained in this manner. The ceramic substrates <NUM> and <NUM> can also be manufactured in a similar manner. The base material <NUM> has the alignment mark <NUM>. Accordingly, the identification mark <NUM> being damaged when the scribe lines L1 and L2 are formed can be suppressed even when the end portion <NUM> is provided with the identification mark <NUM> with the end portion <NUM> reduced in size. In addition, even in a case where the identification mark <NUM> is provided after the formation of the scribe lines L1 and L2, the identification mark <NUM> can be provided in the narrow end portion <NUM> with high positional accuracy.

The ceramic substrate <NUM> described above is used for a composite substrate manufacturing method according to an embodiment. In other words, this manufacturing method has a step of laminating each metal sheet <NUM> so as to cover the main surface 100A and the main surface 100B of the ceramic substrate <NUM> and joining the pair of metal sheets <NUM> to the ceramic substrate <NUM> to obtain a composite substrate. The metal sheet <NUM> may have a flat plate shape similar to that of the ceramic substrate <NUM>. The pair of metal sheets <NUM> are respectively joined to the main surface 100A and the main surface 100B of the ceramic substrate <NUM> via a brazing material.

Specifically, first, the paste-shaped brazing material is applied to the main surface 100A and the main surface 100B of the ceramic substrate <NUM> by a method such as a roll coater method, a screen printing method, and a transfer method. The brazing material contains, for example, a metal component such as silver and titanium, an organic solvent, and a binder. The viscosity of the brazing material may be, for example, <NUM> to <NUM> Pa·s. The content of the organic solvent in the brazing material may be, for example, <NUM> to <NUM>% by mass. The content of the binder in the brazing material may be, for example, <NUM> to <NUM>% by mass.

<FIG> is a perspective view illustrating the ceramic substrate <NUM> to which a brazing material <NUM> is applied. Although only the main surface 100A side is illustrated in <FIG>, the brazing material <NUM> may be applied to the main surface 100B side as well. When the brazing material <NUM> is applied, the positional accuracy of the brazing material <NUM> on the main surface 100A and the main surface 100B can be enhanced by performing alignment using the alignment mark <NUM>. Also, the positional accuracy of the ceramic substrate <NUM> and the metal sheet <NUM> on the composite substrate <NUM> can be enhanced by performing alignment using the alignment mark <NUM> when the metal sheet <NUM> is attached to the main surface 100A and the main surface 100B of the ceramic substrate <NUM>.

In this manner, the metal sheet <NUM> is attached to the main surface 100A and the main surface 100B of the ceramic substrate <NUM> to which the brazing material <NUM> is applied. Then, the ceramic substrate <NUM> and the metal sheet <NUM> are sufficiently joined by heating in a heating furnace to obtain the composite substrate <NUM> illustrated in <FIG>. The heating temperature may be, for example, <NUM> to <NUM>. The atmosphere in the furnace may be an inert gas such as nitrogen, and the process may be performed under reduced pressure below atmospheric pressure or under vacuum. The heating furnace may be a continuous furnace where a plurality of joined bodies are continuously manufactured or a furnace where one or more joined bodies are batch-manufactured. The heating may be performed while pressing a joined body in the lamination direction.

In a modification example, a metal sheet having notch portions at its four corners may be used instead of the metal sheet <NUM>. In this manner, a composite substrate where the alignment mark <NUM> and the identification mark <NUM> are exposed from the notch portion can be obtained. In another modification example, the composite substrate <NUM> of <FIG> may be obtained by joining the ceramic substrate <NUM> of <FIG> so as to be sandwiched between the metal sheet <NUM> and the metal sheet <NUM>.

In these manufacturing methods, a ceramic substrate having an alignment mark is used, and thus alignment can be easily performed during joining. Accordingly, the composite substrate can be manufactured at a low manufacturing cost. In addition, the alignment accuracy of the ceramic and metal sheets can be enhanced since the ceramic substrate capable of enhancing alignment accuracy is used.

A circuit substrate manufacturing method according to an embodiment has a step of forming the independent conductor portion <NUM> for each section <NUM> by removing a part of the metal sheet <NUM> in the composite substrate <NUM> following the composite substrate manufacturing method described above. This step may be performed by, for example, photolithography. Specifically, first, a photosensitive resist is printed on a main surface 200A of the composite substrate <NUM> as illustrated in <FIG>. Then, a resist pattern having a predetermined shape is formed using an exposure apparatus. The resist may be a negative-type resist or a positive-type resist. The uncured resist is removed by, for example, washing.

<FIG> is a perspective view illustrating the composite substrate <NUM> where resist patterns <NUM> are formed on the main surface 200A. Although only the main surface 200A side is illustrated in <FIG>, similar resist patterns are formed on the main surface 200B side as well. The resist patterns <NUM> are formed in the regions of the main surface 200A and the main surface 200B that correspond to the sections <NUM> of the ceramic substrate <NUM>.

After the resist pattern <NUM> is formed, the part of the metal sheet <NUM> that is not covered with the resist pattern <NUM> is removed by etching. As a result, the main surface 100A and the main surface 100B of the ceramic substrate <NUM> are exposed at the part. At this time, the alignment mark <NUM> and the identification mark <NUM> in the end portion of the main surface 100A (100B) are exposed as illustrated in <FIG>. Subsequently, the resist pattern <NUM> is removed and the independent conductor portion <NUM> is formed for each section <NUM>. As illustrated in <FIG>, the conductor portions <NUM> are formed so as to form a pair for each section <NUM> with the ceramic substrate <NUM> interposed therebetween. The circuit substrate <NUM> as illustrated in <FIG> is obtained by the above steps.

In the circuit substrate <NUM> obtained by such a manufacturing method, the alignment mark <NUM> is exposed on the main surface 100A (100B) of the ceramic substrate <NUM>. Accordingly, the alignment accuracy at a time when, for example, a divided substrate is obtained by division can be improved. In addition, the circuit substrate <NUM> can be manufactured at a low manufacturing cost since the ceramic substrate <NUM> is used.

In a modification example, the composite substrate <NUM> illustrated in <FIG> may be used instead of the composite substrate <NUM>. In the composite substrate <NUM>, the alignment mark <NUM> is exposed from the notch portion <NUM>, and thus alignment can be performed using the alignment mark <NUM> during the formation of the resist pattern <NUM> for forming the conductor portion <NUM> and etching as well. Accordingly, the shape accuracy of the conductor portion <NUM> can be sufficiently enhanced. In addition, the identification mark <NUM> is exposed from the notch portion <NUM>, and thus traceability can be consistently ensured until the circuit substrate <NUM> is obtained from the ceramic substrate <NUM>.

Although several embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, but only by the subject-matter of the appended claims. For example, the conductor portions <NUM> provided in the sections <NUM> do not have to have the same shape and the conductor portions <NUM> in the sections <NUM> may have different shapes. In addition, the ceramic substrate and the composite substrate may have a shape other than the shape of a quadrangular prism.

Any surface treatment may be applied to the conductor portion <NUM> of the circuit substrate <NUM>. For example, a part of the surface of the conductor portion <NUM> may be coated with a protective layer such as a solder resist with another part of the surface of the conductor portion <NUM> plated.

According to the present disclosure, a ceramic substrate capable of enhancing alignment accuracy and a method for manufacturing the same can be provided. In addition, the present disclosure is capable of providing a composite substrate in which the positional accuracy of metal and ceramic substrates is excellent and a method for manufacturing the same. In addition, the present disclosure is capable of providing a circuit substrate excellent in alignment accuracy when a divided substrate is obtained by division and a method for manufacturing the same.

Claim 1:
A composite substrate (<NUM>, <NUM>) comprising a ceramic substrate (<NUM>, <NUM>, <NUM>) and a metal sheet (<NUM>, <NUM>), wherein
the ceramic substrate (<NUM>, <NUM>, <NUM>) comprises a main surface (100A, 101A, 102A) having a plurality of sections (<NUM>) divided by scribe lines (L1, L2, L3, L4) and an alignment mark (<NUM>, 11A),
wherein the main surface (100A, 101A, 102A) has at least one of the scribe lines (L1, L2, L3, L4) closer to a center (C) of the main surface (100A, 101A, 102A) than the alignment mark (<NUM>, 11A);
wherein the metal sheet (<NUM>, <NUM>) is joined to the ceramic substrate (<NUM>, <NUM>, <NUM>) so as to cover the main surface (100A, 101A, 102A),
characterized in that
the alignment mark (<NUM>, 11A) is provided in an end portion (<NUM>) delimited by an outer edge (<NUM>) of the main surface (100A, 101A, 102A) and the scribe line (L1, L2, L3, L4) positioned farthest from the center (C) of the main surface (100A, 101A, 102A),
wherein the metal sheet (<NUM>, <NUM>) has at least one selected from a group consisting of a notch portion (<NUM>) and a through hole, and
wherein the alignment mark (<NUM>, 11A) is exposed from the notch portion (<NUM>) or the through hole.