Circuit boards and electronic modules

Abstract

The present invention provides a substrate that improves the functionality of the space enclosed by the frame, which includes the element mounting area. [Solution] The substrate comprises a base portion and a frame portion located on the upper surface of the base portion. The base portion has an element mounting area on its upper surface on which elements are mounted. The frame portion has a first inner surface, a second inner surface, and a first corner surface connecting the first inner surface and the second inner surface to each other. The surface roughness of the first corner surface is greater than the surface roughness of at least a portion of the first inner surface.

Description

Technical Field

[0001] The present disclosure relates to a substrate and an electronic module.

Background Art

[0002] Conventionally, a method for manufacturing a ceramic component having a cavity for accommodating an element has been known (see, for example, Patent Document 1).

[0003] The method for manufacturing a ceramic component described in Patent Document 1 includes a laser processing step and a firing step. An example of the ceramic component is a ceramic package for mounting an element. In the laser processing step, a cavity is formed by irradiating a laminate in which a plurality of ceramic green sheets are laminated or a single layer body that is a single ceramic green sheet with a laser. Then, in the firing step, the laminate or the single layer body having the cavity is sintered to obtain a ceramic package.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique described in Patent Document 1, the aim is to miniaturize the ceramic component. The technique described in Patent Document 1 enables formation of a cavity having a shape corresponding to an element with high positional accuracy or enables microfabrication in the laser processing step.

[0006] Regarding the functions related to the space in a substrate having a space including an element mounting region for mounting an element, there is room for further consideration.

Means for Solving the Problems

[0007] To solve the above problems, a substrate in one aspect of the present disclosure comprises a base portion and a frame portion located on the upper surface of the base portion, wherein the base portion has an element mounting region on its upper surface on which an element is mounted, and the frame portion has a first inner surface, a second inner surface, and a first corner surface connecting the first inner surface and the second inner surface to each other, wherein the surface roughness of the first corner surface is greater than the surface roughness of at least a portion of the first inner surface. [Effects of the Invention]

[0008] According to one aspect of this disclosure, it is possible to provide a substrate having an element mounting area and having a new function added to it. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic perspective view showing the configuration of the substrate in Embodiment 1 of this disclosure. [Figure 2] This is a schematic plan view showing the configuration of the substrate in Embodiment 1 of the present disclosure. [Figure 3] This is an optical microscope image corresponding to the cross-section viewed along the line III-III shown in Figure 2. [Figure 4] Figure 2 shows an optical microscope image of the first inner surface of the frame portion of the substrate shown in Figure 2, viewed from direction IV shown in Figure 2. [Figure 5] This is a perspective view showing an example of an electronic module in which elements are mounted on an element mounting area of ​​a substrate, according to Embodiment 1 of the present disclosure. [Figure 6] This is a schematic diagram illustrating a substrate in one configuration example of Embodiment 1 of the present disclosure. [Figure 7] This is a schematic diagram illustrating a substrate in one configuration example of Embodiment 1 of the present disclosure. [Figure 8] This is a schematic perspective view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. [Figure 9] This is a schematic plan view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. [Figure 10] Figure 9 shows an optical microscope image of the inner surface of a recess in the substrate, viewed from the X direction shown in Figure 9. [Figure 11] This is a schematic perspective view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. [Figure 12] This is a schematic diagram illustrating the substrate in Embodiment 2 of the present disclosure. [Figure 13] This is a partial plan view showing an enlarged view of the area around the first corner surface of the substrate in Embodiment 2 of the present disclosure. [Figure 14] This is a schematic plan view showing the configuration of the substrate in Embodiment 3 of the present disclosure. [Modes for carrying out the invention]

[0010] [Embodiment 1] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. However, the following description is intended to provide a better understanding of the spirit of the invention and does not limit the present disclosure unless otherwise specified. For the sake of clarity, the drawings referenced in the following description show only the main components necessary to explain the embodiment, and for the sake of brevity, explanations of known technical matters will be omitted as appropriate.

[0011] Figure 1 is a schematic perspective view showing the configuration of the substrate in Embodiment 1 of this disclosure. Figure 2 is a schematic plan view showing the configuration of the substrate in Embodiment 1 of this disclosure.

[0012] As shown in Figures 1 and 2, the substrate 1 in one embodiment of the present disclosure comprises a base portion 10 and a frame portion 20 located on the upper surface 10T of the base portion 10. The base portion 10 has an element mounting region R on its upper surface 10T on which an element is mounted. The frame portion 20 has a first inner surface 21, a second inner surface 22, and a first corner surface 12C connecting the first inner surface 21 and the second inner surface 22 to each other. The surface roughness of the first corner surface 12C is greater than the surface roughness of at least a portion of the first inner surface 21. The substrate 1 may also be referred to as an element mounting substrate.

[0013] Hereinafter, in order to facilitate the understanding of the substrate 1 in an embodiment of the present disclosure, first, the definition of terms and the like in the present disclosure will be described, and then the schematic configuration of the substrate 1 in an embodiment of the present disclosure will be described. Thereafter, the advantages of the substrate 1 and various configuration examples will be described in detail.

[0014] <Definition of terms and the like> In this specification, as an index representing the surface roughness of a certain surface, various known indexes can be appropriately used. When measuring the surface roughness of a plurality of different surfaces and comparing them with each other, a specific measuring method and measuring conditions may be commonly used to compare the measured values of the surface roughness of each surface. For example, for each surface to be compared for surface roughness, the measured values obtained by measuring under the same conditions using the same measuring device may be compared with each other.

[0015] As an example of a known index representing surface roughness, the arithmetic mean roughness Ra, the maximum height Rz, the ten-point mean roughness RzJIS, etc. can be mentioned. When using these indexes, for example, JIS B060 The surface roughness may be measured in accordance with the standard of 1:2013. As another example of a known index representing surface roughness, the arithmetic mean height Sa, the root mean square height Sq, etc. can be mentioned. When using these indexes, for example, the surface roughness may be measured in accordance with the standard of ISO 25178. As an example of a method for measuring surface roughness, for example, a scanning method using a stylus, an optical interference method using a laser or the like, an image inspection method, etc. can be mentioned.

[0016] Also, in this specification, for convenience of explanation, the thickness direction (height direction) of the substrate 1 is defined as the Z-axis direction, and the XY plane perpendicular to the Z-axis direction is defined. In FIGS. 1 and 2, the XYZ axes are illustrated in the figures. Viewing an object with a line of sight parallel to the Z-axis is referred to as "plan view", and when viewing it perspectively, it is referred to as "plan perspective view". The side where the frame portion 20 is located with respect to the base portion 10 is defined as the upper side (the positive Z-axis direction side). Similarly, in the following description in this specification, the XYZ axis directions are defined and described, and the XYZ axes are illustrated in each figure for reference.

[0017] <Overall configuration of the circuit board> In the examples shown in Figures 1 and 2, the substrate 1 has a substantially rectangular shape in plan view, and each of the four corners SC of the rectangle has a chamfered shape. The substrate 1 may have a first side surface S1, a second side surface S2, a third side surface S3, and a fourth side surface S4. The corners SC may be the parts that connect two adjacent surfaces from the first to fourth side surfaces S1 to S4. The corners SC may be the parts used as the starting point for division when dividing the substrate 1 from a multi-piece substrate. The substrate 1 may have conductive parts (so-called castellations) located at the corners SC. The substrate 1 is not limited to the examples shown in Figures 1 and 2, and the corners SC of the substrate 1 do not have to be chamfered.

[0018] The substrate 1 may be, for example, an insulating substrate. At least one of the base portion 10 and the frame portion 20 may include a plurality of laminated insulating layers, in which case the plurality of insulating layers may be integral with each other, or there may be conductors between the plurality of insulating layers. In this disclosure, integral with each other means that there are no boundaries, and includes, for example, cases in which each insulating layer is sintered so that the boundaries of each insulating layer are indistinguishable. At least one of the base portion 10 and the frame portion 20 may be a single-layer insulating layer. The insulating layer may include, for example, an electrically insulating ceramic or resin. The base portion 10 and the frame portion 20 may be made of an insulating material. Examples of insulating materials that can be used include ceramic materials such as aluminum oxide (alumina), silicon oxide, and aluminum nitride, epoxy resins, polyimide resins, olefin resins, polyphenylene resins, organic resin materials such as polytetrafluoroethylene (PTFE), glass materials, etc. The frame portion 20 may be made of the same material as the base portion 10, may contain the same material as the base portion 10, may contain a different material than the base portion 10, or may be made of a different material than the base portion 10.

[0019] The substrate 1 may be composed of a single layer, in which case the base portion 10 and the frame portion 20 may be integral with each other. For example, the substrate 1 may be manufactured by a process of forming recesses by processing a rectangular parallelepiped semi-finished product.

[0020] The substrate 1 may have a bottomed recess (first recess) 30 that opens upward. The recess 30 may constitute a housing space for housing at least a portion of the element. The substrate 1 may have an element mounting region R within the recess 30. The element mounting region R may be a region on which at least one or more elements are mounted.

[0021] In the example shown in Figure 1, the shape of the element mounting area R is rectangular, but it is not limited to this. In the example shown in Figure 1, the element mounting area R does not overlap with the multiple electrodes 51 in a planar perspective view, but the element mounting area R may overlap with the multiple electrodes 51 in a planar perspective view. The element mounting area R may have a shape corresponding to the shape of the element to be mounted. The specific form of the element mounted in the element mounting area R is not particularly limited. For example, electronic elements, electronic components, etc., may be mounted in the element mounting area R. A combination of an element and an inorganic substrate may be mounted in the element mounting area R. In this case, for example, the element may be mounted on an inorganic substrate, and a sub-substrate on which the element is mounted may be joined to the element mounting region R. As the sub-substrate, an insulating substrate such as an inorganic substrate can be used. The inorganic substrate may be a substrate containing inorganic materials such as glass, quartz, or ceramics. The specific material of the inorganic substrate is not particularly limited.

[0022] The element mounting area R may be the area that overlaps with the element to be mounted in a plan view. The element mounting area R may also be the area where the element or the sub-substrate contacts the upper surface 10T of the base 10, in which case the element or sub-substrate may extend beyond the element mounting area R in a plan view. Alternatively, if so-called alignment marks are used as markers when mounting the element on the substrate 1, the element mounting area R may be the area enclosed by imaginary lines connecting the alignment marks.

[0023] The recess 30 may be surrounded by the frame portion 20. The element mounting area R may be surrounded by the frame portion 20. In the examples shown in Figures 1 and 2, the bottom surface of the recess 30 may consist entirely of the top surface 10T of the base portion 10. That is, in a plan view, the area surrounded by the outer edge of the bottom surface of the recess 30 and the area of ​​the top surface 10T located within the recess 30 may be the same. However, the substrate 1 only needs to have the element mounting area R located on the top surface 10T of the base portion 10, and may have, for example, a multi-stage recess structure. The substrate 1 may further have one or more recesses within the recess 30 that are recessed below the top surface 10T, and may have through holes penetrating to the back surface of the substrate 1. Specific configuration examples will be described later.

[0024] Here, for example, if the entire substrate 1 is integrally constructed, the base portion 10 and the frame portion 20 may be defined as follows. That is, the surface on which the element mounting area R is located can be defined as the upper surface 10T, and in the Z-axis direction (thickness direction), the portion above the upper surface 10T can be defined as the frame portion 20, and the portion below the upper surface 10T, including the upper surface 10T, can be defined as the base portion 10.

[0025] The substrate 1 may have, for example, a frame portion 20 in a plan view that overlaps with the base portion 10, where the area is 10% to 90% of the area of ​​the base portion 10 in a plan view. Furthermore, the outer edge of the frame portion 20 does not necessarily coincide with the outer edge of the base portion 10 in a plan view. The area of ​​the base portion 10 in a plan view is the area enclosed by the outer edge of the base portion 10 in a plan view, and this area does not change depending, for example, whether or not a through hole is formed in the base portion 10. The substrate 1 may have, for example, a recess 30 in a plan view, where the area is 10% to 90% of the area of ​​the base portion 10 in a plan view. The element mounting area R may occupy, for example, 30% to 98% of the area of ​​the recess 30 in a plan view.

[0026] The frame portion 20 may have a third inner surface 23 facing the first inner surface 21 and a fourth inner surface 24 facing the second inner surface 22. The first to fourth inner surfaces 21 to 24 may each extend along the first to fourth plate surfaces S1 to S4. The frame portion 20 may have a second corner surface 23C connecting the second inner surface 22 and the third inner surface 23, a third corner surface 34C connecting the third inner surface 23 and the fourth inner surface 24, and a fourth corner surface 41C connecting the fourth inner surface 24 and the first inner surface 21.

[0027] For example, in a plan view, the length of one side of the outermost edge of the substrate 1, assuming that the corner SC is not chamfered, may be between 2 mm and 100 mm. The distance between opposing first inner surface 21 and third inner surface 23 in the frame portion 20 of the substrate 1 may be between 0.3 mm and 95 mm. The distance between opposing second inner surface 22 and fourth inner surface 24 in the frame portion 20 of the substrate 1 may be between 0.3 mm and 95 mm. For example, the thickness of the base portion 10 of the substrate 1 may be between 0.05 mm and 5 mm, and the thickness of the frame portion 20 may be between 0.05 mm and 5 mm.

[0028] The substrate 1 may have multiple electrodes 51 located on its upper surface 10T. The electrodes 51 may be electrically connected, for example, to the electrodes of an element mounted in the element mounting area R, via bonding wires or conductive bonding material. In one embodiment of the substrate 1, for example, a portion of the electrodes 51 may overlap with the element mounting area R in a planar perspective, in which case the electrodes of the element may be bonded to the electrodes 51 via a conductive bonding material by a method including flip-chip bonding. The substrate 1 does not have to have electrodes 51 located on its upper surface 10T; for example, multiple electrodes 51 may be located on the upper surface 20T of the frame portion 20. The substrate 1 may have multiple electrodes 51 located on both its upper surface 10T and its upper surface 20T.

[0029] The advantages of the substrate 1 in one embodiment of this disclosure will be described below with reference to the drawings. Figure 3 is an optical microscope image corresponding to the cross-section viewed along the line III-III in Figure 2. Figure 4 is an optical microscope image of the first inner surface of the frame portion of the substrate shown in Figure 2, viewed from direction IV in Figure 2. Figure 5 is a perspective view showing an example of an electronic module in Embodiment 1 of this disclosure, in which elements are mounted on the element mounting area of ​​the substrate.

[0030] As shown in Figure 3, the first corner surface 12C has fine irregularities on its surface. The presence of a relatively large first protrusion 12P can be seen on the first corner surface 12C. In contrast, as shown in Figure 4, the first inner surface 21 has fewer irregularities and is a smoother surface compared to the first corner surface 12C. Thus, in the substrate 1, the surface roughness of the first corner surface 12C is greater than the surface roughness of at least a portion of the first inner surface 21.

[0031] As shown in Figure 5, an electronic module 100 in one embodiment of the present disclosure comprises a substrate 1 and an element 2 located in an element mounting area R. With the progress of miniaturization of the electronic module 100, the sizes of the substrate 1 and the element 2 have become very small. When mounting the element 2 on the substrate 1, it is necessary to align the element 2, which is held by a holder such as a collet, with respect to the element mounting area R of the substrate 1. On the substrate 1, for example, if the position of the element 2 is different from a predetermined mounting position, the misaligned element 2 can be caught by the first corner surface 12C and the first inner surface 21. Alternatively, in the electronic module 100 after the element 2 has been mounted on the substrate 1, if the element 2 is misaligned due to some factor, the misaligned element 2 can be caught by the first corner surface 12C and the first inner surface 21. More details are as follows.

[0032] When element 2 contacts the first inner surface 21, the contact portion of element 2 with the first inner surface 21 experiences relatively low frictional resistance. In other words, element 2 makes relatively smooth contact with the first inner surface 21. On the other hand, when element 2 contacts the relatively rough first corner surface 12C, the contact portion of element 2 with the first corner surface 12C experiences relatively high frictional resistance. That is, within the space enclosed by the frame portion 20, the contact portion catches on the first corner surface 12C, allowing the displaced element 2 to be caught by the first corner surface 12C and the first inner surface 21. Therefore, the possibility of element 2 being displaced above the upper surface 20T of the frame portion 20 and flying out of the substrate 1 can be reduced. If element 2 is displaced above a predetermined position and protrudes from the upper surface 20T, there is a possibility that element 2 may be damaged by contact with jigs or external parts. By using the substrate 1, the possibility of element 2 being significantly displaced in the Z-axis direction (thickness direction) can be reduced. Therefore, the possibility of damage to element 2 can be reduced. Thus, according to one aspect of the present disclosure, a substrate 1 is provided which has a space enclosed by a frame portion 20 that includes an element mounting area R, and which has a new function related to the above space added. An example of a new function is the function of reducing the possibility of damage to element 2. Furthermore, the substrate 1 also has the following functions.

[0033] Furthermore, various sensors can be used to align element 2 with respect to the element mounting area R. For example, when aligning elements based on image analysis, the position of the element mounting area can be determined. This may be difficult. Therefore, it may be necessary to pre-set alignment marks. In contrast, in substrate 1, the surface roughness of the first corner surface 12C is relatively large, which allows for a difference in reflectivity between the first corner surface 12C and the first inner surface 21. Therefore, the positions of the first corner surface 12C and the first inner surface 21 can be easily identified by image analysis. As a result, the position of the element mounting area R can be accurately determined. Accordingly, according to one aspect of this disclosure, it is possible to easily align the element 2 with respect to the element mounting area R.

[0034] Furthermore, in general, during the manufacturing process of an object, there is a possibility that some unwanted foreign matter may be unintentionally introduced. In substrate 1, the surface roughness of at least a portion of the first inner surface 21 is smaller than that of the first corner surface 12C, thereby reducing the possibility of contamination by unwanted foreign matter originating from the first inner surface 21. Also, if unwanted foreign matter is introduced into the space surrounded by the frame portion 20, such foreign matter may preferentially adhere to the first corner surface 12C, which has a relatively larger surface roughness than the first inner surface 21. In substrate 1, the distance from the element mounting area R to the first corner surface 12C can be made relatively larger than the distance from the element mounting area R to the first inner surface 21. Therefore, it is easier to improve the cleanliness of the element mounting area R and its vicinity.

[0035] In one embodiment of the present disclosure, the surface roughness of the substrate 1 may be greater than the surface roughness of at least a portion of the first inner surface 21 and also greater than the surface roughness of at least a portion of the second inner surface 22. In the substrate 1, the surface roughness of the second corner surface 23C may be greater than the surface roughness of at least a portion of the second inner surface 22 and also greater than the surface roughness of at least a portion of the third inner surface 23. In the substrate 1, the surface roughness of the third corner surface 34C may be greater than the surface roughness of at least a portion of the third inner surface 23 and also greater than the surface roughness of at least a portion of the fourth inner surface 24. In the substrate 1, the surface roughness of the fourth corner surface 41C may be greater than the surface roughness of at least a portion of the fourth inner surface 24 and also greater than the surface roughness of at least a portion of the first inner surface 21. According to the above configuration, the aforementioned effects of the substrate 1 can be further improved.

[0036] In one embodiment of the present disclosure, the substrate 1 may have a curved surface at least in part. Having a curved surface on the first corner surface 12C makes it easier to reduce stress. Therefore, the possibility of cracks occurring in the frame portion 20 can be effectively reduced. Furthermore, if the element 2 comes into contact with the first corner surface 12C, the possibility of damage to the element 2 and / or the substrate 1 can be effectively reduced.

[0037] In substrate 1, the fact that the first to fourth corner surfaces 12C, 23C, 34C, and 41C each have curved surfaces makes it easier to reduce stress. In substrate 1, the first corner surface 12C and the third corner surface 34C are diagonally opposite each other, and the second corner surface 23C and the fourth corner surface 41C are diagonally opposite each other. Therefore, it is possible to make it less likely for stress to occur locally in substrate 1.

[0038] The method for manufacturing the substrate 1 in one embodiment of this disclosure is not particularly limited, as long as it can form a frame portion 20 having a first inner surface 21 and a first corner surface 12C. The substrate 1 may be manufactured, for example, by molding or die forming, and then surface treatment applied to the inner surface of the frame portion 20. If the substrate 1 is a ceramic substrate, for example, a ceramic substrate can be manufactured by firing a green sheet that has been processed such as punching or cutting. For example, the first corner surface 12C may correspond to a portion of the green sheet that has been punched. The second to fourth corner surfaces 23C, 34C, and 41C may correspond to portions of the green sheet that have been punched. For example, surface roughness occurs on the punched surface of the green sheet due to friction with the surface of the punch used for punching. Surface treatment applied to the inner surface of the frame portion 20 of the ceramic substrate after firing. The substrate 1 may be manufactured by performing a process.

[0039] For example, if the cross-section of the green sheet before firing, corresponding to the first inner surface 21, is entirely a cut surface or a polished surface, then the surface roughness of the first inner surface 21 may be uniform across its entire surface. Alternatively, for example, in the case of (i) or (ii) below, the surface roughness of the first inner surface 21 may differ in parts: (i) In the case where a portion of the cross-section of the green sheet before firing, corresponding to the first inner surface 21, is used as the cut surface; (ii) With respect to the first inner surface 21, a portion is made into a relatively smooth surface polished surface, while another portion or the remainder is made into a fracture surface or a relatively rough surface polished surface.

[0040] The second to fourth inner surfaces 22, 23, and 24 may have a uniform surface roughness throughout, or the surface roughness may differ in parts.

[0041] <this> Element 2 may be bonded to the element mounting area R via a bonding material such as brazing material, glass, or adhesive, or it may be indirectly mounted to the element mounting area R via a member such as a base or a sub-substrate. Element 2 may be a semiconductor element, piezoelectric element, sensor element, passive element, etc., for example, a CCD (Charge-Coupled Device) element, a CMOS ( Element 2 may be a Complementary Metal-Oxide Semiconductor (MEC) element, etc. Element 2 may be a display element such as a liquid crystal display. Element 2 may be a piezoelectric element, a capacitive element, or a passive component such as a resistor. Element 2 may be a semiconductor integrated circuit element, an optoelectronic semiconductor element, a sensor element, a MEMS (Micro electro-mechanical systems) element, etc. Multiple elements of multiple types may be mounted on the electronic module 100.

[0042] If element 2 is a light-emitting element, the substrate 1 has a relatively small surface roughness on the first inner surface 21, which makes it easier to reduce the amount of stray light generated inside the frame 20.

[0043] <Example Configuration> Figure 6 is a schematic diagram illustrating a substrate in one configuration example of Embodiment 1 of the present disclosure. The figure indicated by reference numeral 6001 in Figure 6 is a schematic perspective view showing the configuration of the substrate in one configuration example of Embodiment 1 of the present disclosure. The figure indicated by reference numeral 6002 in Figure 6 is a schematic partial plan view showing the configuration of the substrate in one configuration example of Embodiment 1 of the present disclosure.

[0044] As shown in Figure 6, in a plan view, the first virtual line VL1 is defined as a line that is a virtual extension of the side 21T located at the upper end of the first inner surface 21. In the substrate 1, at least a portion of the first corner surface 12C is located outside the first virtual line VL1 in a plan view, with respect to the element mounting area R. Outside the first virtual line VL1 with respect to the element mounting area R means the region on the opposite side of the region divided by the first virtual line VL1 in a plan view from the side where the element mounting area R is located, in other words, the region on the side where the first plate surface S1 is located. By having at least a portion of the first corner surface 12C have a recessed shape that is located outside the first virtual line VL1, the aforementioned effects of the substrate 1 can be further improved.

[0045] In a plan view, the line obtained by virtually extending the edge 22T located at the upper end of the second inner surface 22 is called the second virtual line VL2, the line obtained by virtually extending the edge 23T located at the upper end of the third inner surface 23 is called the third virtual line VL3, and the line obtained by virtually extending the edge 24T located at the upper end of the fourth inner surface 24 is called the fourth virtual line VL4.

[0046] On substrate 1, at least a portion of the first corner surface 12C may be located outside at least one of the first virtual line VL1 and the second virtual line VL2 in a plan view, with respect to the element mounting area R. On substrate 1, at least a portion of the second corner surface 23C may be located outside at least one of the second virtual line VL2 and the third virtual line VL3 in a plan view, with respect to the element mounting area R. On substrate 1, at least a portion of the third corner surface 34C may be located outside at least one of the third virtual line VL3 and the fourth virtual line VL4 in a plan view, with respect to the element mounting area R. On substrate 1, at least a portion of the fourth corner surface 41C may be located outside at least one of the fourth virtual line VL4 and the first virtual line VL1 in a plan view, with respect to the element mounting area R.

[0047] The substrate 1 further comprises a wiring conductor 50, the wiring conductor 50 including an electrode 51 located in a first region A1 surrounded by the frame portion 20 on the upper surface 10T of the base portion 10, and an internal conductor 52 extending from the electrode 51 to the space between the base portion 10 and the frame portion 20. Although the diagram indicated by reference numeral 6002 in Figure 6 shows one wiring conductor 50, it goes without saying that the substrate 1 may have multiple wiring conductors 50.

[0048] As described above, in substrate 1, since the surface roughness of at least a portion of the first inner surface 21 is smaller than that of the first corner surface 12C, the possibility of foreign matter such as debris adhering to or accumulating on the first inner surface 21 can be reduced. Therefore, the possibility of foreign matter such as debris adhering to or accumulating on the first inner surface 21 peeling off onto the electrode 51 can be effectively reduced.

[0049] The wiring conductor 50 extends to a position where the internal conductor 52, which extends from the electrode 51, overlaps with the frame portion 20 in a planar perspective view. Therefore, the wiring conductor 50 can be connected to various other conductors at the position where it overlaps with the frame portion 20 in a planar perspective view. Other conductors include branch wiring and other conductors in the same plane, via conductors extending in the Z-axis direction, castellations, and side electrodes.

[0050] For example, when the wiring conductor 50 is connected to a via conductor (not shown) at a position that overlaps with the frame portion 20 in a planar perspective view, it is easier to improve the strength of the substrate 1 than when the via conductor is located in a relatively thin portion of the substrate 1. Furthermore, in this case, the degree of freedom for the position of the via in a planar view can be increased. The degree of freedom for the number of vias connected to the wiring conductor 50 can also be increased. Therefore, the wiring density can be optimized. The resistance or impedance can also be optimized. In addition, by connecting the via conductor to the internal conductor 52 rather than the electrode 51, it is easier to improve the flatness of the electrode 51.

[0051] Figure 7 is a schematic diagram illustrating a substrate in one configuration example of Embodiment 1 of the present disclosure. The figure indicated by reference numeral 7001 in Figure 7 is a magnified partial perspective view showing the vicinity of the first corner surface of the substrate in one configuration example of Embodiment 1 of the present disclosure. The figure indicated by reference numeral 7002 in Figure 7 is a partial plan view schematically showing the configuration of the substrate in one configuration example of Embodiment 1 of the present disclosure.

[0052] As shown in Figure 7, the substrate 1 may further include an insulating coating portion 60 located in the first region A1 of the upper surface 10T and in contact with the first inner surface 21. A portion of the insulating coating portion 60 may cover a portion of the electrode 51. The insulating coating portion 60 may be made of an insulating material. The insulating coating portion 60 may contain electrically insulating ceramics or resin.

[0053] Even if a conductive material adheres to the first inner surface 21, the insulating coating portion 60 in contact with the first inner surface 21 covers a portion of the electrode 51, thereby reducing the possibility of a short circuit occurring between the electrode 51 and another electrode or wiring conductor. Furthermore, if plating is applied to various conductors provided on the substrate 1, and the plating material extends along the first inner surface 21, However, this reduces the possibility of a short circuit occurring between electrode 51 and another electrode or wiring conductor. Furthermore, because a portion of electrode 51 is covered by a portion of the insulating coating 60, electrode 51 is less likely to peel off from the upper surface 10T.

[0054] The substrate 1 may further include a corner conductor 55 located between the base portion 10 and the frame portion 20, and extending from the first corner surface 12C toward the element mounting area R. The corner conductor 55 may function as an electrode, or it may be a conductor provided for direction identification. The corner conductor 55 may extend from the first corner surface 12C toward the first area A1 of the upper surface 10T, and the direction in which the corner conductor 55 extends is not particularly limited. The corner conductor 55 is positioned relatively far from the element mounting area R. Therefore, when the electronic module 100 after element mounting is viewed from the outside, the visibility of the corner conductor 55 can be increased, and as a result, the direction of the electronic module 100 can be easily identified. In addition, when the corner conductor 55 is used as a connection electrode to a component other than the element 2, the connection portion between the component and the corner conductor 55 is less likely to interfere with the element 2, making it easier to connect the component and the corner conductor 55.

[0055] Figure 8 is a schematic perspective view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. Figure 9 is a schematic plan view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. Figure 10 is an optical microscope image of the inner surface of a recess in the substrate shown in Figure 9, viewed from the X direction shown in Figure 9.

[0056] In the examples shown in Figures 8 and 9, the base portion 10 may have a recess (second recess) 70 located inside the frame portion 20 in a plan view and included within the element mounting area R. The substrate 1 may have a two-tiered recess in the portion surrounded by the frame portion 20 in a plan view. The recess 70 is located below the recess 30 within the element mounting area R. The recess 70 may have a bottom surface, which may be formed by the base portion 10. Not limited to the examples shown in Figures 8 and 9, the recess 70 may have a hole that penetrates to the back surface of the substrate 1. In the examples shown in Figures 8 and 9, the shape of the recess 70 in a plan view is rectangular, but is not limited to this. The recess 70 may have a shape corresponding to the shape of the element mounting area R. In the substrate 1, for example, in a plan view, the length of one side of the outer edge of the recess 70 may be 0.3 mm or more and 90 mm or less. By having the recess 70, the substrate 1 can be made lighter. Furthermore, by placing a thermistor or integrated circuit in the recess 70, it is possible to provide a substrate 1 that allows for miniaturization of the electronic module 100 compared to a substrate without the recess 70.

[0057] In one embodiment of the present disclosure, the surface roughness of the inner surface 71 of the recess 70 may be greater than the surface roughness of at least a portion of the first inner surface 21. The method for manufacturing the substrate 1 having such a recess 70 is not particularly limited. For example, the recess 70 may be formed by further processing the substrate 1 shown in Figure 1, etc. Alternatively, if the substrate 1 is a ceramic substrate, the substrate 1 having the recess 70 can be manufactured by firing a green sheet on which the portion corresponding to the recess 70 has been formed.

[0058] As shown in Figure 10, the recess 70 has fine irregularities on its surface, and the inner surface 71 of the recess 70 may contain a plurality of second protrusions 71P. The plurality of second protrusions 71P may all protrude in the same direction. When we say that the plurality of second protrusions 71P all protrude in the "same direction", we mean that on the inner surface 71 of the recess 70, the protruding directions of all the second protrusions 71P are aligned upward in the Z-axis direction (thickness direction), or aligned downward in the Z-axis direction (thickness direction).

[0059] In the examples shown in Figures 8 and 9, the base 10 may include multiple insulating layers. The base 10 may have a first base 101 and a second base 102 located on the first base 101. If the substrate 1 is a multilayer wiring board, an internal wiring layer may be located between the first base portion 101 and the second base portion 102. The first base portion 101 and the second base portion 102 may each be single-layer or multi-layer insulating layers. A recess 70 may be formed by a hole formed in the second base portion 102. The bottom surface of the recess 70 may consist entirely of the top surface 101T of the first base portion 101. Furthermore, another recess may be formed by a hole formed in the first base portion 101. The number of layers of the base portion 10 is not limited to two.

[0060] The inner surface 71 of the recess 70 may, for example, correspond to the inner surface of the punched portion in the green sheet before firing, which becomes the second base portion 102 after firing. The direction of protrusion of the plurality of second protrusions 71P on the inner surface 71 may be determined according to the direction in which the green sheet before firing was punched.

[0061] Here, the first corner surface 12C of the frame portion 20 (see Figure 3) may include a plurality of first protrusions 12P, as described above. Similar to what was described above regarding the plurality of second protrusions 71P on the inner surface 71, the plurality of first protrusions 12P may all protrude in the same direction. When we say that the plurality of first protrusions 12P all protrude in the "same direction", it means that on the first corner surface 12C of the frame portion 20, the protrusion directions of all the first protrusions 12P are aligned upward in the Z-axis direction (thickness direction), or aligned downward in the Z-axis direction (thickness direction). The protrusion directions of the plurality of first protrusions 12P on the first corner surface 12C along the thickness direction may be the same as, or different from, the protrusion directions of the plurality of second protrusions 71P on the inner surface 71 along the thickness direction.

[0062] Figure 11 is a schematic plan view showing the configuration of a substrate in one example of Embodiment 1 of the present disclosure. In the example shown in Figure 11, the base portion 10 may have a raised portion 80 that is located at least in the first region A1 surrounded by the frame portion 20 on the upper surface 10T, along the inside of the first corner surface 12C, and is raised above the portion along the first inner surface 21.

[0063] In the example substrate 1 shown in Figure 11, for example, if the position of element 2 differs from the predetermined mounting position, the lower surface of the misaligned element 2 may come into contact with the raised portion 80. The contact portion of element 2 with the raised portion 80 experiences relatively higher frictional resistance than when the raised portion 80 is absent (in other words, when the first region A1 is entirely flat). That is, within the space enclosed by the frame portion 20, the contact portion may catch on the raised portion 80, and the misalignment of element 2 may be prevented by the raised portion 80. Here, if element 2 is displaced in the XY axis direction from the predetermined position, there is a possibility that electrical connection between predetermined electrodes will not be made. By using substrate 1, the possibility of element 2 being significantly displaced in the XY axis direction can be reduced. Therefore, the possibility of connection failure in element 2 can be reduced.

[0064] In the substrate 1, a portion of the raised portion 80 and a portion of the element mounting area R may overlap in a plan view. The raised portion 80 does not have to overlap with the element mounting area R in a plan view. The first corner surface 12C may correspond, for example, to the inner surface of a punched portion in the green sheet before firing, which becomes the frame portion 20 after firing. Hereinafter, the punched portion will be referred to as the corner hole portion. When manufacturing the laminate of green sheets, the portion of the green sheet that becomes the base portion 10 after firing that overlaps with the corner hole portion does not need to be pressed, while the portion that does not overlap with the corner hole portion may be pressed. As a result, the raised portion 80 may be formed on the substrate 1 obtained by firing the laminate. The height of the raised portion 80 in the Z-axis direction may be 1 μm to 80 μm higher than the peripheral portion of the raised portion 80 in the first region A1 of the upper surface 10T.

[0065] In the example shown in Figure 11, the substrate 1 may have four raised portions 80, each of which is located inside the first to fourth corner surfaces 12C, 23C, 34C, and 41C, respectively. It may be located at least in the part that follows it.

[0066] <Other examples> The overall shape of the substrate 1 is not particularly limited and may be rectangular, polygonal, or circular in plan view. The shape of the base portion 10 is not limited to a rectangular shape and may be circular or polygonal. The outer surfaces of the base portion 10 and the outer surfaces of the frame portion 20 do not have to be aligned with each other.

[0067] The first inner surface 21 of the frame portion 20 may be inclined with respect to the Z-axis direction. The first corner surface 12C may be inclined with respect to the Z-axis direction.

[0068] [Embodiment 2] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0069] Figure 12 is a schematic diagram illustrating the substrate in Embodiment 2 of the present disclosure. The figure indicated by reference numeral 1201 in Figure 12 is a perspective view schematically showing the configuration of the substrate in Embodiment 2 of the present disclosure. The figure indicated by reference numeral 1202 in Figure 12 is a plan view schematically showing the configuration of the substrate in Embodiment 2 of the present disclosure. Figure 13 is a partial plan view showing an enlarged view of the area around the first corner surface of the substrate in Embodiment 2 of the present disclosure.

[0070] As shown in Figures 12 and 13, the substrate 1 in Embodiment 2 of the present disclosure may have a greater curvature of the first corner surface 12C than that of Embodiment 1. In the example shown in Figures 12 and 13, at least a portion of the first corner surface 12C may be located outside the first virtual line VL1 and outside the second virtual line VL2 with respect to the element mounting area R in a plan view.

[0071] According to the above configuration, the possibility of contact between the element 2 and the first corner surface 12C can be reduced. Even in this case, a substrate 1 can be provided in which the space enclosed by the frame portion 20, which includes the element mounting area R, has the new functions described in Embodiment 1 added to it. One example of a new function is the ability to easily improve the cleanliness of the element mounting area R and its vicinity.

[0072] Furthermore, by making the surface roughness of the first corner surface 12C, which is less likely to come into contact with the element 2, greater than the surface roughness of the first inner surface 21, the heat dissipation performance of the substrate 1 can be improved while reducing the possibility that the irregularities formed on the first corner surface 12C will be worn away due to contact between the element 2 and the first corner surface 12C.

[0073] [Embodiment 3] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0074] Figure 14 is a schematic plan view showing the configuration of the substrate in Embodiment 3 of the present disclosure. As shown in Figure 14, at least a portion of the first corner surface 12C of the substrate 1 may be planar. The first corner surface 12C may correspond, for example, to the inner surface of the portion of the green sheet that will become the frame portion 20 after firing that has been punched out by a rectangular prism-shaped punch. In the example shown in Figure 14, the base portion 10 may have a rectangular raised portion 80 that is located at least in the portion along the inside of the first corner surface 12C and is raised above the portion along the first inner surface 21. Figure 14 In the example substrate 1 shown, the area of ​​the first corner surface 12C can be made relatively small. Therefore, the amount of machining required by the machining tool can be reduced. As a result, the wear of the machining tool can be reduced. In addition, by making the area of ​​the frame portion 20 relatively large, the overall heat capacity of the substrate can be improved and the area that can be wired can be expanded.

[0075] [Additional notes] The inventions described in this disclosure have been explained based on the drawings and embodiments (configuration examples). However, the inventions described in this disclosure are not limited to the embodiments described above. That is, the inventions described in this disclosure can be modified in various ways within the scope shown in this disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the inventions described in this disclosure. In other words, it should be noted that it is easy for those skilled in the art to make various modifications or alterations based on this disclosure. Furthermore, it should be noted that these modifications or alterations are included in the scope of this disclosure.

[0076] 〔summary〕 A substrate in embodiment 1 of the present disclosure comprises a base portion and a frame portion located on the upper surface of the base portion, wherein the base portion has an element mounting region on its upper surface on which an element is mounted, and the frame portion has a first inner surface, a second inner surface, and a first corner surface connecting the first inner surface and the second inner surface to each other, wherein the surface roughness of the first corner surface is greater than the surface roughness of at least a portion of the first inner surface.

[0077] In embodiment 2 of the present disclosure, the substrate is such that, in embodiment 1, the first corner surface is curved in at least a portion thereof.

[0078] In the third aspect of the present disclosure, in the first or second aspect, in a plan view, a straight line obtained by virtually extending the edge located at the upper end of the first inner surface is defined as the first imaginary line, and at least a portion of the first corner surface is located outside the first imaginary line with respect to the element mounting area in a plan view.

[0079] A substrate in aspect 4 of the present disclosure further comprises a wiring conductor in any one of aspects 1 to 3, the wiring conductor including an electrode located in a first region of the upper surface of the base that is surrounded by the frame, and an internal conductor extending from the electrode to the space between the base and the frame.

[0080] The substrate in embodiment 5 of the present disclosure further comprises an insulating coating portion located in the first region of the upper surface and in contact with the first inner surface, wherein a portion of the insulating coating portion covers a portion of the electrode.

[0081] In embodiment 6 of the present disclosure, the substrate, in any one embodiment of embodiments 1 to 5, has a base portion that is located at least in the portion of the upper surface enclosed by the frame portion that is aligned with the inside of the first corner surface and that is raised above the portion aligned with the first inner surface.

[0082] In embodiment 7 of the present disclosure, the substrate, in any one embodiment of embodiments 1 to 6, has a first corner surface which includes a plurality of first protrusions, all of which protrude in the same direction.

[0083] In embodiment 8 of the present disclosure, the substrate, in any one embodiment of embodiments 1 to 7, has a base portion that is located inside the frame portion in a plan view and is included in the element mounting area.

[0084] In embodiment 9 of the present disclosure, the substrate, in embodiment 8, has a surface roughness greater than that of at least a portion of the surface roughness of the inner surface of the recess.

[0085] In embodiment 10 of the present disclosure, the substrate, in embodiment 8 or 9, has an inner surface of the recess that includes a plurality of second protrusions, all of which protrude in the same direction.

[0086] In the substrate according to embodiment 11 of the present disclosure, in any one embodiment of embodiments 1 to 10, in a plan view, a first imaginary line is defined as a line obtained by virtually extending the edge located at the upper end of the first inner surface, and a second imaginary line is defined as a line obtained by virtually extending the edge located at the upper end of the second inner surface, and at least a portion of the first corner surface is located, in a plan view, outside the first imaginary line and outside the second imaginary line with respect to the element mounting area.

[0087] The substrate in embodiment 12 of the present disclosure further comprises a corner conductor located between the base and the frame and extending from the first corner surface toward the element mounting area, in any one embodiment of embodiments 1 to 11.

[0088] The electronic module in embodiment 13 of the present disclosure comprises a substrate according to any one embodiment of embodiments 1 to 12, and an element located in the element mounting area. [Explanation of Symbols]

[0089] 1 circuit board 2. 10 base 10T (base) upper surface 12C First Corner 23C Second Corner 34C Third Corner 41C Fourth Corner 12P First protrusion 20 Frame section 20T (Top surface of the frame) 21 1st inner surface 21T (side located at the upper end of the first inner surface) 22 Second inner surface 22T (side located at the upper end of the second inner surface) 23 Third inner surface 24 4th inner surface 30 recesses 50 Wiring conductors 51 electrode 52 Inner conductor 55 Corner Conductor 60 Insulating coating 70 recess 71 Inner surface 71P Second protrusion 80 Ridge 100 Electronic Modules 101 1st base 101T (Top surface of the first base) 102 Second base A1 1st area R element mounting area S1 1st plate side S2 2nd plate side S3 3rd plate side S4 4th plate side SC corner VL1 First Virtual Line VL2 Second Virtual Line VL3 Third Virtual Line VL4 4th virtual line

Claims

1. It comprises a base and a frame located on the upper surface of the base, The base portion has an element mounting area on its upper surface on which an element is mounted. The frame portion has a first inner surface, a second inner surface, and a first corner surface connecting the first inner surface and the second inner surface to each other. A substrate in which the surface roughness of the first corner surface is greater than the surface roughness of at least a portion of the first inner surface.

2. The substrate according to claim 1, wherein at least a portion of the first corner surface is curved.

3. In a plan view, the first imaginary line is defined as a straight line obtained by virtually extending the edge located at the upper end of the first inner surface. The substrate according to claim 1, wherein at least a portion of the first corner surface is located outside the first imaginary line with respect to the element mounting area in a plan view.

4. Further equipped with wiring conductors, The aforementioned wiring conductor is An electrode located in the first region of the upper surface of the base that is surrounded by the frame portion, A substrate according to any one of claims 1 to 3, comprising an internal conductor extending from the electrode to the space between the base and the frame.

5. The upper surface further comprises an insulating coating portion located in the first region and in contact with the first inner surface, The substrate according to claim 4, wherein a part of the insulating coating covers a part of the electrode.

6. The substrate according to any one of claims 1 to 3, wherein the base portion is located at least in the portion of the upper surface enclosed by the frame portion that is aligned with the inside of the first corner surface and has a raised portion that is raised above the portion that is aligned with the first inner surface.

7. The first corner surface includes a plurality of first protrusions, The substrate according to any one of claims 1 to 3, wherein all of the plurality of first protrusions protrude in the same direction.

8. The substrate according to any one of claims 1 to 3, wherein the base portion has a recess that is located inside the frame portion in a plan view and is included in the element mounting area.

9. The substrate according to claim 8, wherein the surface roughness of the inner surface of the recess is greater than the surface roughness of at least a portion of the first inner surface.

10. The inner surface of the recess includes a plurality of second protrusions, The substrate according to claim 8, wherein all of the aforementioned multiple second protrusions protrude in the same direction.

11. In a plan view, a line obtained by virtually extending the edge located at the upper end of the second inner surface is defined as the second imaginary line. The substrate according to claim 3, wherein at least a portion of the first corner surface is located, in a plan view, outside the first virtual line and outside the second virtual line with respect to the element mounting area.

12. The invention further comprises a corner conductor located between the base and the frame and extending from the first corner surface toward the element mounting area, according to any one of claims 1 to 3. substrate.

13. The substrate according to claim 1, An electronic module comprising an element located in the aforementioned element mounting region.

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