Electronic component-embedded substrate and electronic component-embedded substrate assembly sheet

Abstract

Provided is an electronic component-embedded substrate 1 comprising: a substrate 10 that has a first main surface 11 and a second main surface 12 which face each other in the thickness direction; a cavity 70 that opens at the first main surface 11 of the substrate 10; and an electronic component 50 that is accommodated in the cavity 70, wherein in a top view, the cavity 70 has a substantially polygonal shape in which at least one of the vertices of the polygon has a protrusion 75.

Description

Electronic component embedded board and electronic component embedded board assembly sheet

[0001] The present invention relates to a substrate with built-in electronic components and an electronic component built-in substrate assembly sheet.

[0002] Patent Document 1 discloses a ceramic multilayer substrate with a cavity, in which electronic components are mounted.

[0003] Patent Document 1 describes that the joint between the mounting portion and the ceramic substrate is susceptible to stress, which can cause cracks, etc. As a solution to this problem, a recess is formed on the main surface opposite the main surface having the cavity, and a resin layer is provided that covers the recess and has a flat surface, which increases the thickness of the resin layer in the recess, thereby improving the strength of the ceramic layer that forms the bottom portion of the cavity and improving impact resistance.

[0004] Japanese Patent Application Laid-Open No. 2006-310498

[0005] The structure described in Patent Document 1 can improve the strength of the bottom portion of the cavity. However, there is a problem in that the strength of the peripheral portion of the cavity is insufficient. The cavity generally has a polygonal shape such as a square or rectangle when viewed from above, but the vertices of the polygon lack strength and cracks can occur.

[0006] Furthermore, the top view shape of the electronic component to be mounted in the cavity is often a square or rectangle, and the top view shape of the cavity is often a similar square or rectangle that is slightly larger than the top view shape of the electronic component. When mounting an electronic component having a square top view shape in a cavity also having a square top view shape, the corners of the electronic component may come into contact with the vertices of the inner periphery of the cavity, which may result in scratches on the corners of the electronic component. Therefore, it is possible to increase the dimensions of the cavity to widen the distance between the corners of the electronic component and the vertices of the inner periphery of the cavity, so that the corners of the electronic component and the vertices of the inner periphery of the cavity are less likely to come into contact even if the mounting position is misaligned. However, in situations where there is a demand for smaller dimensions of electronic component-embedded substrates and higher mounting density, increasing the dimensions of the cavity is not desirable.

[0007] The present invention has been made to solve the above problems, and aims to provide a substrate with built-in electronic components that can improve the strength of the area surrounding the cavity and prevent damage to the corners of the electronic components.

[0008] The electronic component-embedded substrate of the present invention is an electronic component-embedded substrate comprising a substrate having a first main surface and a second main surface that are opposite to each other in the thickness direction, a cavity that opens to the first main surface of the substrate, and an electronic component accommodated in the cavity, wherein, when viewed from above, the shape of the cavity is an approximately polygonal shape in which at least one of the vertices of the polygon has a protrusion.

[0009] The electronic component-embedded substrate assembly sheet of the present invention is an electronic component-embedded substrate assembly sheet having multiple electronic component-embedded substrate units attached thereto, which can be cut to obtain multiple electronic component-embedded substrates, and each of the multiple electronic component-embedded substrates is an electronic component-embedded substrate assembly sheet of the present invention.

[0010] According to the present invention, it is possible to provide a substrate with built-in electronic components that can improve the strength of the area around the cavity and prevent damage to the corners of the electronic components.

[0011] FIG. 1 is a cross-sectional view schematically showing an example of the configuration of an electronic component-embedded substrate of the present invention. FIG. 2 is a plan view schematically showing an example of the shape of a cavity as viewed from above. FIG. 3 is a plan view schematically showing an example of a state in which an electronic component is housed in the cavity shown in FIG. 2. FIG. 4 is a plan view schematically showing another example of the shape of a cavity as viewed from above. FIG. 5 is a plan view schematically showing another example of the shape of a cavity as viewed from above. FIG. 6 is a plan view schematically showing another example of the shape of a cavity as viewed from above. FIG. 7 is a cross-sectional view schematically showing another example of the configuration of an electronic component-embedded substrate of the present invention. FIG. 8 is a top view schematically showing an example of the shape of a cavity as viewed from above in an electronic component-embedded substrate collective sheet. FIG. 9 is a top view schematically showing an example of an electronic component-embedded substrate collective sheet for comparison with FIG. 8, in which the shape of the cavity as viewed from above is different. FIG. 10 is a top view schematically showing another example of the shape of a cavity as viewed from above in an electronic component-embedded substrate collective sheet. FIG. 11 is a cross-sectional view schematically showing another example of the configuration of the electronic component built-in substrate of the present invention.

[0012] The electronic component built-in substrate and electronic component built-in substrate assembly sheet of the present invention will be described below. However, the present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope that does not change the gist of the present invention. Note that a combination of two or more of the individual preferred configurations described below also constitutes the present invention.

[0013] [Electronic component built-in substrate] Figure 1 is a cross-sectional view showing a schematic example of the configuration of an electronic component built-in substrate of the present invention. The electronic component built-in substrate 1 shown in Figure 1 has a substrate 10 formed by laminating an insulating layer 30 and a constraining layer 40. The substrate 10 has a first main surface 11 and a second main surface 12 that face each other in the thickness direction (Z direction in Figure 1).

[0014] Wiring 21 and interlayer connection conductors 22 are provided inside the substrate 10. The wiring conductors and interlayer connection conductors are preferably made of a material that can be co-fired with the low-temperature co-fired ceramic material, such as Cu, Ag, Au, and alloys thereof. Cu, Ag, and Au have low resistance and are therefore particularly suitable for use in high-frequency applications of the ceramic substrate. The patterns of the wiring and interlayer connection conductors are not particularly limited.

[0015] The insulating layer preferably contains a low-temperature co-fired ceramic material (LTCC material). The low-temperature co-fired ceramic material is a ceramic material that can be fired at a temperature of 1000°C or less and can be co-fired with Au, Ag, Cu, or the like, which have low resistivity. Specific examples of the low-temperature co-fired ceramic material include glass composite low-temperature co-fired ceramic materials obtained by mixing ceramic powder such as alumina, zirconia, magnesia, or forsterite with borosilicate glass; ZnO-MgO-Al ２ O ３ -SiO ２ Glass-ceramic low-temperature fired ceramic material using BaO-Al ２ O ３ -SiO ２ ceramic powder and Al ２ O ３ -CaO-SiO ２ -MgO-B ２ O ３ Examples of suitable ceramic materials include non-glass-based low-temperature fired ceramic materials using ceramic powders.

[0016] The constraining layer is a layer containing a metal oxide that does not substantially sinter at the sintering temperature of the low-temperature co-fired ceramic material and does not shrink or shrinks only slightly during firing. Examples of metal oxides that do not substantially sinter at the sintering temperature of the low-temperature co-fired ceramic material include alumina, silica, zirconia, titania, silica, niobium pentoxide, tantalum pentoxide, and magnesia, with alumina and silica being preferred. These metal oxides can be used alone or in combination, taking into account the high-frequency characteristics of the ceramic substrate.

[0017] The metal oxide contained in each of the plurality of constraining layers of the substrate is preferably the same type, more preferably at least one of alumina and silica, and even more preferably alumina.

[0018] The constraining layer preferably contains glass in addition to the metal oxide. When the constraining layer contains glass, examples of the glass contained in the constraining layer include B—Si-M (M is an alkali metal or alkaline earth metal) based glasses.

[0019] The insulating layers and constraining layers that make up the substrate are preferably stacked alternately, but in some cases, two or more insulating layers may be stacked continuously, or two or more constraining layers may be stacked continuously. In the substrate 10 shown in Figure 1, the insulating layers 30 and the constraining layers 40 are stacked alternately. Also, the substrate 10 does not need to be provided with the constraining layers 40, and only the insulating layers 30 may be stacked continuously.

[0020] An electronic component 51 is mounted on the first main surface 11 of the substrate 10, and an electronic component 52 is mounted on the second main surface 12. In addition, a mounting electrode 61 is provided on the second main surface 12, and the mounting electrode 61 is used to mount the electronic component built-in substrate 1 on another substrate. A plating layer 62 is provided on the surface of the mounting electrode 61.

[0021] The substrate 10 is provided with a cavity 70 that opens to the first main surface 11 of the substrate 10, and an electronic component 50 is housed in the cavity 70. In the electronic component-embedded substrate 1 shown in FIG. 1 , the electronic component 50 is mounted on a bottom surface 78 of the cavity 70, and the top surface of the electronic component 50 (the surface on the first main surface 11 side of the substrate 10) protrudes above an opening 79 of the cavity 70 (coplanar with the first main surface 11). In such a case, the electronic component is also considered to be housed in the cavity. Furthermore, the electronic component is also considered to be housed in the cavity when the top surface of the electronic component is located below the opening of the cavity (coplanar with the first main surface). Details of the shape of the cavity will be described later.

[0022] Examples of the electronic components (electronic components 50, 51, 52) included in the electronic component built-in substrate 1 include semiconductor chips (dies), passive components such as capacitors and coils, and filters.

[0023] The interior of the cavity 70, the periphery of the electronic component 51, and the periphery of the electronic component 52 are sealed with a sealing material 80. The sealing material 80 is made of a sealing resin, and either a thermosetting resin or a thermoplastic resin may be used as the sealing resin. Examples of thermosetting resins include phenolic resin, epoxy resin, polyester resin, silicone resin, and polyimide resin. Examples of thermoplastic resins include thermoplastic liquid crystal polymer (LCP), thermoplastic polyimide resin, polyether ether ketone resin (PEEK), and polyphenylene sulfide resin (PPS).

[0024] The sealing resin may contain additives such as fillers, for example, glass, silica, aluminum oxide, aluminum nitride, boron nitride, and the like.

[0025] An external shielding film 90 is provided around the electronic component built-in substrate 1. The external shielding film 90 is provided on the surface of the substrate 10 other than the surface on the second main surface 12 side (the surface where the mounting electrodes 61 are exposed from the sealing material 80).

[0026] In the electronic component built-in substrate of the present invention, electronic components do not have to be mounted on the first and second main surfaces of the substrate, and an external shielding film does not have to be provided around the electronic component built-in substrate.

[0027] In the electronic component built-in substrate of the present invention, the cavity has a generally polygonal shape in top view, with at least one of the vertices of the polygon having a protrusion.

[0028] 2 is a plan view schematically illustrating an example of the shape of a cavity as viewed from above. Fig. 2 shows only the cavity 71 and the insulating layer 30 around it, and does not show the electronic components housed in the cavity or the sealing resin filled in the cavity. The same components are shown in other plan views illustrating the shape of the cavity in this specification.

[0029] 2 has a substantially square shape in top view, and the upper right vertex of the square has a protrusion 75. The cavity 71 has one protrusion 75. In this specification, the term "substantially polygonal shape" refers to a shape in which the shape excluding the protrusion is a polygon and the protrusion is added to the polygon.

[0030] When the cavity has a shape with protrusions when viewed from above, the strength of the area surrounding the cavity can be improved. When the cavity has a polygonal shape such as a square or rectangle, stress is concentrated at the vertices of the polygon, but by providing protrusions, the stress is dispersed to the protrusions at the vertices. Therefore, the strength of the area surrounding the cavity can be improved.

[0031] Although the shape of the protrusions is not particularly limited, it is preferable that the tips of the protrusions are curved. By not making the tips of the protrusions sharp, stress concentration at the tips of the protrusions is prevented, and cracks are prevented from occurring at the protrusions.

[0032] Furthermore, if the cavity has a shape with a protrusion when viewed from above, the adhesion of the sealing resin filled in the cavity to the cavity can be improved.

[0033] FIG. 3 is a plan view schematically illustrating an example of a state in which an electronic component is accommodated in the cavity shown in FIG. 3 . FIG. 3 illustrates a case in which the position of the electronic component 50 in the cavity 71 is offset to the upper right. If a protrusion 75 is provided in the upper right of the cavity 71, there is no vertex of a square in the upper right of the cavity 71. Therefore, even if the position of the electronic component 50 is offset to the upper right, the corners 50 a of the electronic component 50 do not contact the vertices of the inner periphery of the cavity. Furthermore, even if the electronic component 50 contacts the inner wall of the cavity 71, only the edges of the electronic component 50 make contact. This prevents the corners 50 a of the electronic component 50 from being scratched.

[0034] In the electronic component-embedded substrate of the present invention, the cavity preferably has a generally polygonal shape in which at least two of the polygonal vertices have protrusions, and the protrusions preferably protrude in different directions. Furthermore, the cavity preferably has a generally quadrangular shape in which all of the quadrangular vertices have protrusions, and the protrusions preferably protrude in different directions. Furthermore, the cavity preferably has a generally square shape in which all of the square vertices have protrusions, and the protrusions preferably protrude in different directions, and the protrusions preferably extend along the direction of one of the sides that contact the vertices at which the protrusions are provided. Examples of such cavities will be described with reference to the drawings.

[0035] Fig. 4 is a plan view schematically illustrating another example of the shape of a cavity in a top view. The shape of the cavity 72 shown in Fig. 4 is substantially square in top view, and the four vertices of the square have protrusions 75a, 75b, 75c, and 75d, respectively. The number of protrusions 75 in the cavity 72 is four.

[0036] When the cavity has a rectangular shape in top view with protrusions at all of the vertices of the rectangle, stress is dispersed to the protrusions at all of the vertices of the rectangle. This further improves the strength of the surrounding area of ​​the cavity. Furthermore, when an electronic component is housed in the cavity, the corners of the electronic component do not come into contact with the vertices of the inner periphery of the cavity, regardless of which vertex of the rectangle the electronic component is positioned in. This prevents scratches at any of the corners of the electronic component.

[0037] The directions in which the protrusions 75 protrude from the square (protrusion directions) are all different. Starting with protrusion 75a located in the upper right corner, protrusions 75b, 75c, and 75d are arranged clockwise. Protrusion 75a protrudes in the +X direction, protrusion 75b protrudes in the -Y direction, protrusion 75c protrudes in the -X direction, and protrusion 75d protrudes in the +Y direction. The protrusion directions are indicated by arrows near each protrusion.

[0038] If the protrusions all protrude in different directions, the direction of the stress distributed at the vertices of the rectangle will also be different. The fact that the stress is not applied in the same direction makes it less likely for cracks to occur around the cavity. This also has the effect of making cracks less likely to occur when the sheet is made into an electronic component embedded substrate assembly sheet, but this effect will be discussed later.

[0039] In the cavity 72 shown in Fig. 4, the direction in which the protrusion 75 protrudes from the square is along the direction of extension of one of the sides that contact the vertices at which the protrusions are provided. The four sides of the square that form the outer periphery of the cavity 72 are the sides that contact the vertices at which the protrusions are provided. The four sides of the square are respectively referred to as sides 76a, 76b, 76c, and 76d.

[0040] The protrusion 75a located at the top right protrudes from a vertex 77a (a vertex that does not actually exist) formed by connecting sides 76a and 76b of the square, with the protrusion 75a extending in the direction of extension of side 76a. The protrusion 75b located at the bottom right protrudes from a vertex 77b (a vertex that does not actually exist) formed by connecting sides 76b and 76c of the square, with the protrusion 75b extending in the direction of extension of side 76b. The protrusion 75c located at the bottom left protrudes from a vertex 77c (a vertex that does not actually exist) formed by connecting sides 76c and 76d of the square, with the protrusion 75c extending in the direction of extension of side 76c. The protrusion 75d located at the top left protrudes from a vertex 77d (a vertex that does not actually exist) formed by connecting sides 76d and 76a of the square, with the protrusion 75d extending in the direction of extension of side 76d.

[0041] A cavity shape such as that shown in Figure 4, i.e., a cavity shape (top view shape) in which the protrusions from a quadrangle all protrude in different directions and follow the direction of extension of one of the sides that contact the vertices at which the protrusions are provided, is called a windmill shape.

[0042] In the electronic component-embedded substrate of the present invention, the cavity has a substantially rectangular shape with protrusions at all vertices of the rectangle, and when the protrusions protrude in different directions, the length of at least one of the protrusions may be different from the lengths of the other protrusions. Examples of such cavities will be described with reference to the drawings.

[0043] Fig. 5 is a plan view schematically illustrating another example of the shape of a cavity in a top view. The shape of the cavity 73 shown in Fig. 5 in a top view is substantially square, and the four vertices of the square have protrusions 75a, 75b, 75c, and 75d, respectively. The cavity 73 has four protrusions 75. The protrusion length (the length indicated by the double-headed arrow P) of one of the protrusions, protrusion 75a, is longer than the protrusion lengths of the other protrusions.

[0044] The stress applied to each protrusion can be adjusted by changing the protrusion length. If the cavity is located near a corner of the substrate (close to the upper left in FIG. 5), a protrusion that is longer than the other protrusions (protrusion 75a in FIG. 5) may be positioned near the center of the substrate.

[0045] Furthermore, when the shape of the substrate is rectangular in top view, the extension direction of a protrusion that is longer than the other protrusions may be along the long side direction of the rectangle of the substrate. In Fig. 5, the shape of the substrate in top view is rectangular, and the long side direction of the rectangle of the substrate is the X direction. The extension direction (the direction of the double arrow P) of protrusion 75a that is longer than the other protrusions is along the X direction. The long side direction of the rectangle of the substrate has a wider space for the protrusions to extend than the short side direction, so it is suitable for increasing the length of the protrusions.

[0046] In addition, the cavity may have a generally rectangular shape in top view, with protrusions at all of the vertices of the rectangle, and the direction in which a protrusion that is longer than the other protrusions extends may be along the short side direction of the cavity rectangle. Figure 6 is a plan view schematically showing another example of the cavity shape in top view. The cavity 74 shown in Figure 6 has a generally rectangular shape in top view, with the long side of the rectangle extending along the X direction and the short side of the rectangle extending along the Y direction.

[0047] The four vertices of the rectangle have protrusions 75a, 75b, 75c, and 75d, respectively. The cavity 74 has four protrusions 75. The protrusion lengths (lengths indicated by double-headed arrows P) of two of the protrusions, protrusions 75b and 75d, are longer than the protrusion lengths of the other protrusions (protrusions 75a and 75c). In FIG. 6 , the cavity has a rectangular shape when viewed from above, and the short sides of the cavity rectangle are oriented in the Y direction. The extension directions (directions indicated by double-headed arrows P) of protrusions 75b and 75d, which are longer than the other protrusions, are aligned with the Y direction. When the extension directions of the protrusions longer than the other protrusions are aligned with the short sides of the cavity rectangle, stress during thermal expansion, such as during temperature cycles, can be dispersed, thereby improving crack resistance.

[0048] In addition, by providing a protrusion that is longer than the other protrusions, as in the shape of the cavity shown in Figures 5 and 6, the effect of making it less likely for cracks to occur when the electronic component built-in substrate aggregate sheet is made is also exerted, and this effect will be described later.

[0049] Although the dimensions of the cavity in top view are not particularly limited, if the shape obtained by excluding the protrusion from the approximate polygon is a square, it is preferable that the length of one side of the square is 0.3 mm or more and 2.0 mm or less. If the shape obtained by excluding the protrusion from the approximate polygon is a rectangle, it is preferable that the length of the long side of the rectangle is 0.5 mm or more and 2.0 mm or less, and the length of the short side is 0.3 mm or more and 1.5 mm or less.

[0050] The dimension of the protrusion is indicated by the maximum length of the portion protruding from the polygon, and is preferably 0.010 mm or more and 0.050 mm or less. Furthermore, when there is a protrusion that is longer than other protrusions, the length of the longer protrusion is preferably 0.020 mm or more and 0.100 mm or less, and the length of the other protrusions is preferably 0.010 mm or more and 0.050 mm or less. The difference in length between the longer protrusion and the other protrusions is preferably 0.010 mm or more and 0.050 mm or less.

[0051] The electronic component-embedded substrate of the present invention may further include a second cavity opening to the second main surface of the substrate and a second electronic component housed in the second cavity. Figure 7 is a cross-sectional view schematically showing another example of the configuration of the electronic component-embedded substrate of the present invention. The electronic component-embedded substrate 2 shown in Figure 7 is provided with a second cavity 170 opening to the second main surface 12 of the substrate 10, and a second electronic component 150 is housed in the second cavity 170. When a second cavity is provided, the cavity opening to the first main surface of the substrate may be referred to as the first cavity to distinguish the name. Furthermore, when the second cavity houses the second electronic component, the electronic component housed in the first cavity may be referred to as the first electronic component to distinguish the name.

[0052] The second cavity 170 may have a shape similar to or different from the cavity 70 (first cavity) that opens to the first main surface 11. That is, the second cavity 170 may have a substantially polygonal shape in which at least one of the vertices of the polygon has a protrusion when viewed from above, a polygonal shape without a protrusion, or another shape.

[0053] The electronic components described above can be used as the second electronic component 150. The electronic component 52 mounted on the second main surface 12 of the electronic component-embedded substrate 1 shown in FIG. 1 may be accommodated in the second cavity 170.

[0054] By providing cavities on both the first and second main surfaces of the substrate and accommodating electronic components in the respective cavities, it is possible to improve the volumetric efficiency of component mounting.

[0055] [Electronic component-embedded substrate aggregate sheet] The electronic component-embedded substrate aggregate sheet of the present invention is an electronic component-embedded substrate aggregate sheet having multiple electronic component-embedded substrate units attached thereto, which can be cut to obtain multiple electronic component-embedded substrates, and each of the multiple electronic component-embedded substrates is an electronic component-embedded substrate aggregate sheet of the present invention.

[0056] Furthermore, in the electronic component built-in substrate assembly sheet of the present invention, the shape of the cavity when viewed from above may be a substantially quadrilateral shape with protrusions at all of the vertices of the quadrilateral, and the protrusions may all protrude in different directions.

[0057] Fig. 8 is a top view schematically showing one example of the shape of a cavity in an electronic component built-in substrate aggregate sheet. In Fig. 8, the shape of a cavity in electronic component built-in substrate aggregate sheet 201 on which multiple electronic component built-in substrate units 210 are attached is shown as the shape of cavity 72 shown in Fig. 4. The shape of electronic component built-in substrate unit 210 shown in Fig. 8 in the top view is rectangular, with the longer sides of the rectangle extending in the X direction and the shorter sides extending in the Y direction.

[0058] The electronic component built-in substrate aggregate sheet is an aggregate sheet that can be cut to obtain a plurality of electronic component built-in substrates. An electronic component built-in substrate aggregate sheet 201 shown in Fig. 8 has a total of 16 electronic component built-in substrate units 210 arranged in a 4 x 4 matrix.

[0059] Fig. 9 is a top view schematically showing an example of an electronic component built-in substrate aggregate sheet in comparison with Fig. 8, in which the shape of the cavity in top view is different. The shape of cavity 370 in electronic component built-in substrate unit 310 included in electronic component built-in substrate aggregate sheet 301 shown in Fig. 9 is a square with no protrusions in top view.

[0060] Hereinafter, with reference to FIGS. 8 and 9, the effect of making cracks less likely to occur that is exhibited in an electronic component built-in substrate aggregate sheet on which electronic component built-in substrate units that become the electronic component built-in substrate of the present invention are attached on multiple sides will be described.

[0061] 9 , the sides of the squares that form the top view shapes of the cavities 370 are aligned in the same direction in each electronic component built-in substrate unit 310. Therefore, the direction of stress applied to the vertices of the squares of the cavities due to warping, bending, etc. applied to the electronic component built-in substrate aggregate sheet is aligned along the direction of the sides of the squares (X direction or Y direction). Therefore, stress applied in the same direction and amplified makes it easier for cracks to occur in a specific direction.

[0062] In contrast, in the electronic component built-in substrate aggregate sheet 201 shown in Fig. 8, the cavity 72 has a substantially square shape in top view, with each of the four vertices of the square having a protrusion, and the protrusions protrude in different directions from the square. In this case, stress applied to the vertices of the square of the cavity 72 due to warping or bending of the electronic component built-in substrate aggregate sheet 201 is dispersed in different directions by the protrusions. Therefore, unlike the electronic component built-in substrate aggregate sheet 301 shown in Fig. 9, the electronic component built-in substrate aggregate sheet 201 shown in Fig. 8 has the effect of being less susceptible to cracks.

[0063] In addition, in the electronic component embedded substrate assembly sheet, the length of at least one of the protrusions may be different from the lengths of the other protrusions, and the direction in which the protrusion that is longer than the other protrusions extends may be along the long side direction of the rectangular substrate.

[0064] Fig. 10 is a top view schematically showing another example of the shape of a cavity in an electronic component built-in substrate aggregate sheet when viewed from above. In Fig. 10, the shape of a cavity in electronic component built-in substrate aggregate sheet 202 on which multiple electronic component built-in substrate units 220 are attached is shown as the shape of cavity 73 shown in Fig. 5 when viewed from above. The shape of electronic component built-in substrate unit 220 shown in Fig. 10 when viewed from above is rectangular, with the longer sides of the rectangle extending in the X direction and the shorter sides extending in the Y direction.

[0065] Because the shape of electronic component built-in substrate unit 220 is rectangular when viewed from above, the spacing between adjacent cavities 73 in the X direction and the Y direction is different in electronic component built-in substrate aggregate sheet 202. Spacing Wx between adjacent cavities 73 in the X direction is larger than spacing Wy between adjacent cavities 73 in the Y direction. By setting the extension direction of protrusion 75a, which is longer than the other protrusions, to the direction in which the spacing between cavities 73 is larger (X direction), the crack suppression effect can be improved.

[0066] If the extension direction of a protrusion that is longer than the other protrusions is set in the direction in which the distance between the cavities is smaller, the adjacent cavities will be close to being connected, which will reduce the amount (thickness) of the insulating layer between the cavities and make cracks more likely to occur. From the perspective of preventing this from happening, it may be considered that the extension direction of a protrusion that is longer than the other protrusions is set in the direction in which the distance between the cavities is larger.

[0067] The method for producing the electronic component built-in substrate of the present invention is not particularly limited, but can be, for example, as follows: The electronic component built-in substrate is preferably produced by a method in which an electronic component built-in substrate aggregate sheet having multiple electronic component built-in substrate units attached thereto is produced, and then the sheet is cut to obtain a plurality of electronic component built-in substrates.

[0068] First, an insulating layer sheet that serves as an insulating layer and a constraining layer sheet that serves as a constraining layer are laminated to obtain a laminate. A predetermined conductor pattern may be formed on the insulating layer sheet and the constraining layer sheet. The conductor pattern becomes the wiring and interlayer connection conductor provided inside the substrate body. A hole that serves as a cavity is machined in a part of the laminate using a laser or a router. A laminate with a hole that serves as a cavity is called a cavity laminate. When machining the hole that serves as the cavity, it is preferable to move the laser or router in a single stroke along the outer periphery of the cavity, which makes it easier to create a protrusion. Furthermore, if a protrusion that is longer than other protrusions is desired, the movement path of the laser or router can be changed to create a longer protrusion. Alternatively, a cavity laminate may be obtained by machining a hole that serves as a cavity in each of the insulating layer sheet and the constraining layer sheet, and then laminating the sheets while aligning the hole position.

[0069] Separately, an insulating layer sheet that will become the insulating layer and a constraining layer sheet that will become the constraining layer are laminated to obtain a laminate. No holes that will become cavities are machined in this laminate. The laminate with holes that will become cavities is called the base laminate.

[0070] The base laminate and the cavity laminate are stacked and pressed together, and then fired to obtain a substrate. The surface of the base laminate exposed through the hole in the cavity laminate becomes the bottom of the cavity.

[0071] An electronic component is housed in the cavity of the substrate, and if necessary, electronic components are also mounted on the first and second main surfaces of the substrate. Furthermore, the cavity and the first and second main surfaces of the substrate are sealed with a sealing material.

[0072] The electronic component built-in substrate assembly sheet is then cut to obtain electronic component built-in substrates. An external shielding film may be provided on the periphery of the electronic component built-in substrate.

[0073] Furthermore, by stacking cavity laminates on both sides of the base laminate, it is possible to manufacture a substrate with built-in electronic components that has a second cavity.

[0074] (Modifications of the Electronic Component-Embedded Substrate) In the electronic component-embedded substrate of the present invention, in a cross section cut in the thickness direction, the side surface of the cavity may have an inflection point where the width of the cavity changes, and the side surface of the cavity may have a shape that widens obliquely toward the bottom surface on the side of the cavity closer to the bottom surface than the inflection point. Examples of electronic component-embedded substrates that satisfy this requirement will be described below.

[0075] 11 is a cross-sectional view schematically illustrating another example of the configuration of an electronic component built-in substrate according to the present invention. In the electronic component built-in substrate 3 shown in FIG. 11, a side surface 475 of a cavity 470 has an inflection point 476 at which the width of the cavity 470 changes. The side surface 475 of the cavity 470 is divided into a first side surface 475a located closer to an opening 479 of the cavity 470 than the inflection point 476, and a second side surface 475b located closer to a bottom surface 478 than the inflection point 476.

[0076] 11 , the width of the cavity 470 is constant along the thickness direction on the first side surface 475a. On the other hand, the second side surface 475b has a shape that expands obliquely along the thickness direction from an inflection point 476 toward a bottom surface 478 of the cavity. On the second side surface 475b, the width of the cavity 470 is smallest at the inflection point 476 and largest at the bottom surface 478. On the second side surface 475b, the width of the cavity 470 monotonically increases from the width at the inflection point 476 to the width at the bottom surface 478.

[0077] 11, the bottom surface of the cavity can be enlarged, making it easier to form a mounting land on the bottom surface of the cavity. In addition, the opening at the top of the cavity can be made smaller than the bottom surface of the cavity, preventing the overall size of the cavity from becoming too large.

[0078] Furthermore, since the shape of the side of the cavity is sloped and not stepped, stress is prevented from concentrating at a specific point on the side of the cavity, resulting in an electronic component-embedded substrate that is less likely to develop cracks in the cavity.

[0079] 11, the cavity has a protrusion near the bottom surface of the cavity when viewed from above, and the shape of the cavity near the bottom surface of the cavity when viewed from above is substantially similar to the shape of the cavity near the opening of the cavity when viewed from above, but enlarged.

[0080] When manufacturing the electronic component-embedded substrate, a shallow hole is drilled obliquely using a laser from the surface of the cavity-forming laminate opposite to the surface intended to become the first main surface of the substrate. This process makes it possible to form a cavity in a shape in which the side surfaces of the cavity expand obliquely toward the bottom surface on the bottom side of the cavity from the inflection point.

[0081] Furthermore, by adjusting the pressing conditions (using a higher pressing pressure) in the step of stacking and pressing the base laminate and the cavity laminate together, without performing the step of drilling shallow diagonal holes using a laser from the surface opposite to the surface intended to become the first main surface of the substrate, it is also possible to form a cavity with a shape that widens near the bottom surface. Note that when laser drilling is performed only once, it is preferable to drill from the surface opposite to the surface intended to become the first main surface of the substrate.

[0082] The present specification discloses the following:

[0083] The present disclosure (1) is an electronic component-embedded substrate including a substrate having a first main surface and a second main surface that are opposite to each other in a thickness direction, a cavity that opens to the first main surface of the substrate, and an electronic component housed in the cavity, wherein, when viewed from above, the shape of the cavity is a substantially polygonal shape in which at least one of the vertices of the polygon has a protrusion.

[0084] The present disclosure (2) is the electronic component-embedded substrate according to the present disclosure (1), wherein, in a top view, the shape of the cavity is a substantially polygonal shape in which at least two of the vertices of the polygon have protrusions, and the protrusions protrude in different directions.

[0085] The present disclosure (3) is the electronic component-embedded substrate according to the present disclosure (1) or (2), in which, when viewed from above, the shape of the cavity is a substantially quadrilateral shape in which all of the vertices of the quadrilateral have protrusions, and the protrusions all protrude in different directions.

[0086] The present disclosure (4) is the electronic component built-in substrate according to the present disclosure (3), wherein, in a top view, the length of at least one of the protrusions is different from the lengths of the other protrusions.

[0087] The present disclosure (5) is the electronic component-embedded substrate according to the present disclosure (4), wherein the shape of the substrate is rectangular when viewed from above, and the direction in which one of the protrusions that is longer than the other protrusions extends is along the long side direction of the rectangle of the substrate.

[0088] The present disclosure (6) is the electronic component-embedded substrate according to the present disclosure (4) or (5), wherein, in a top view, the shape of the cavity is a substantially rectangular shape with protrusions at all of the vertices of the rectangle, and the direction in which the protrusions that are longer than the other protrusions extend is along the short side direction of the rectangle of the cavity.

[0089] The present disclosure (7) is the electronic component-embedded substrate according to the present disclosure (3) or (4), wherein, in a top view, the shape of the cavity is approximately square with protrusions at all of the vertices of the square, and the protrusions all protrude in different directions, along the extending direction of any of the sides that contact the vertices at which the protrusions are provided.

[0090] The present disclosure (8) is the electronic component built-in substrate according to any one of the present disclosures (1) to (7), wherein the tip of the protrusion is curved in top view.

[0091] The present disclosure (9) is the electronic component-embedded substrate according to any one of the present disclosures (1) to (8), further comprising a second cavity that opens to the second main surface of the substrate, and a second electronic component accommodated in the second cavity.

[0092] The present disclosure (10) is an electronic component built-in substrate assembly sheet having multiple electronic component built-in substrate units attached on multiple sides, from which multiple electronic component built-in substrates can be obtained by cutting, wherein each of the multiple electronic component built-in substrates is an electronic component built-in substrate according to any one of the present disclosures (1) to (9).

[0093] The present disclosure (11) is the electronic component built-in substrate assembly sheet according to the present disclosure (10), in which, in top view, the shape of the cavities is a substantially quadrilateral shape with protrusions at all of the vertices of the quadrilateral, and the protrusions all protrude in different directions.

[0094] The present disclosure (12) is the electronic component built-in substrate assembly sheet according to the present disclosure (11), wherein the substrate has a rectangular shape in top view, the length of at least one of the protrusions is different from the lengths of the other protrusions, and the direction in which the protrusion that is longer than the other protrusions extends is along the long side direction of the rectangle of the substrate.

[0095] DESCRIPTION OF SYMBOLS 1, 2, 3 Electronic component built-in substrate 10 Substrate 11 First main surface of substrate 12 Second main surface of substrate 21 Wiring 22 Interlayer connection conductor 30 Insulating layer 40 Constraint layer 50 Electronic component (electronic component accommodated in cavity: first electronic component) 50a Corner of electronic component 51 Electronic component (electronic component mounted on first main surface) 52 Electronic component (electronic component mounted on second main surface) 61 Mounting electrode 62 Plating layer 70, 71, 72, 73, 74, 370, 470 Cavity (first cavity) 75, 75a, 75b, 75c, 75d Protruding portion 76a, 76b, 76c, 76d Sides of square forming outer periphery of cavity 77a, 77b, 77c, 77d Vertices of square forming outer periphery of cavity 78, 478 Bottom surface of cavity 79, 479 Opening of cavity 80 Sealant 90 External shielding film 150 Second electronic component 170 Second cavity 201, 202, 301 Electronic component built-in substrate assembly sheet 210, 220, 310 Electronic component built-in substrate unit 475 Side surface of cavity 475a First side surface 475b Second side surface 476 Inflection point

Claims

1. An electronic component-embedded substrate comprising: a substrate having a first main surface and a second main surface opposing each other in a thickness direction; a cavity opening to the first main surface of the substrate; and an electronic component housed in the cavity, wherein, when viewed from above, the shape of the cavity is a substantially polygonal shape with at least one vertex of the polygon having a protrusion.

2. The electronic component embedded substrate according to claim 1, wherein the cavity has a generally polygonal shape in top view, with at least two of the polygon's vertices having protrusions, and the protrusions protrude in different directions.

3. An electronic component built-in substrate as set forth in claim 1 or 2, wherein the shape of the cavity, when viewed from above, is a substantially quadrilateral shape with protrusions at all of the vertices of the quadrilateral, and the protrusions all protrude in different directions.

4. The electronic component built-in substrate according to claim 3, wherein, when viewed from above, the length of at least one of said protrusions is different from the lengths of the other protrusions.

5. The electronic component built-in substrate according to claim 4, wherein the substrate has a rectangular shape when viewed from above, and the direction in which one of the protrusions that is longer than the other protrusions extends is along the long side direction of the rectangle of the substrate.

6. An electronic component-embedded substrate as set forth in claim 4 or 5, wherein, when viewed from above, the shape of the cavity is a substantially rectangular shape with protrusions at all of the vertices of the rectangle, and the direction in which the protrusions that are longer than the other protrusions extend is along the direction of the short side of the rectangle of the cavity.

7. An electronic component-embedded substrate as set forth in claim 3 or 4, wherein the shape of the cavity, when viewed from above, is a substantially square shape with protrusions at all of the vertices of the square, and the protrusions all protrude in different directions, following the extension direction of one of the sides that contact the vertices at which each of the protrusions is provided.

8. The electronic component built-in substrate according to any one of claims 1 to 7, wherein the tip of the protrusion is curved when viewed from above.

9. The electronic component-embedded substrate according to any one of claims 1 to 8, further comprising a second cavity opening to the second main surface of the substrate, and a second electronic component accommodated in the second cavity.

10. An electronic component embedded substrate assembly sheet having multiple electronic component embedded substrate units attached thereto, which can be cut to obtain multiple electronic component embedded substrates, wherein each of the multiple electronic component embedded substrates is an electronic component embedded substrate as defined in any one of claims 1 to 9.

11. The electronic component built-in substrate assembly sheet according to claim 10, wherein the shape of the cavities, when viewed from above, is a substantially quadrilateral shape with protrusions at all of the vertices of the quadrilateral, and the protrusions all protrude in different directions.

12. An electronic component-embedded substrate assembly sheet as described in claim 11, wherein, when viewed from above, the substrate has a rectangular shape, the length of at least one of the protrusions is different from the lengths of the other protrusions, and the direction in which the protrusion that is longer than the other protrusions extends is along the long side direction of the rectangle of the substrate.

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