Multilayered substrate

Abstract

This multilayered substrate has a carbonaceous base material layer and an organic resin layer. The organic resin layer is positioned on the carbonaceous base material layer. The carbonaceous base material layer has a higher thermal conductivity than the organic resin layer.

Description

multilayer board

[0001] The disclosed embodiments relate to a multilayer substrate.

[0002] 2. Description of the Related Art A display device has been proposed that has a laminated structure in which wiring is arranged between a plurality of insulating layers.

[0003] International Publication No. 2021 / 187090

[0004] A multilayer substrate according to one aspect of the embodiment includes a carbonaceous substrate layer and an organic resin layer located on the carbonaceous substrate layer, the organic resin layer having a higher thermal conductivity than the organic resin layer.

[0005] Fig. 1 is a cross-sectional view showing an example of a multilayer substrate according to a first embodiment. Fig. 2 is a cross-sectional view showing an example of a multilayer substrate according to a second embodiment. Fig. 3A is a cross-sectional view showing an example of a multilayer substrate according to a third embodiment. Fig. 3B is a cross-sectional view taken along line A-A in Fig. 3A. Fig. 4 is a cross-sectional view showing an example of a multilayer substrate according to a fourth embodiment.

[0006] The laminated structure described above has room for improvement in terms of heat dissipation.

[0007] Therefore, it is desired to provide a multilayer substrate that can improve heat dissipation.

[0008] Hereinafter, a detailed description will be given of a form for carrying out a multilayer substrate according to the present disclosure (hereinafter referred to as an "embodiment") with reference to the drawings. Note that the wiring substrate according to the present disclosure is not limited to this embodiment. Furthermore, each embodiment can be appropriately combined within the scope of not causing any contradiction in the processing content. Note that, below, the same or similar configurations are given the same reference numerals, and detailed description will be omitted.

[0009] 1 is a cross-sectional view showing an example of a multilayer substrate according to Embodiment 1. As shown in FIG. 1, the multilayer substrate 1 according to Embodiment 1 includes a substrate 10 and an organic resin layer 20.

[0010] The substrate 10 has surfaces 101 and 102 located at both ends in the thickness direction. The surface 101 is located on the organic resin layer 20 side. The surface 102 is located on the opposite side from the organic resin layer 20.

[0011] In other words, the substrate 10 has a surface 101 and a surface 102. The substrate 10 may have a so-called hexahedral shape. The surfaces 101 and 102 may be the surfaces of this hexahedron with the largest areas. The surfaces 101 and 102 may be arranged opposite each other on the substrate 10, as shown in FIG. 1 . In other words, the surfaces 101 and 102 may be arranged opposite each other on the substrate 10, and may each constitute a main surface.

[0012] The substrate 10 has a carbonaceous substrate layer 11. The main material of the carbonaceous substrate layer 11 may be, for example, graphite. The carbonaceous substrate layer 11 may be, for example, a graphite sheet.

[0013] The substrate 10 may be composed of a carbonaceous substrate layer 11. The carbonaceous substrate layer 11 may be used as the substrate 10. The substrate 10 may be a carbonaceous substrate layer 11. In this case, the substrate 10 has high heat dissipation properties and functions as a so-called heat dissipation substrate.

[0014] The organic resin layer 20 is located on the substrate 10. The organic resin layer 20 is located above the carbonaceous substrate layer 11. The organic resin layer 20 has surfaces 201 and 202 located at both ends in the thickness direction. The surface 201 is located on the substrate 10 side, and the surface 202 is located on the opposite side from the substrate 10.

[0015] The organic resin layer 20 is, for example, a so-called organic base material having a polymer material. The organic resin layer 20 may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin. The organic resin layer 20 may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins, or polyphenylene ether resin.

[0016] In this multilayer substrate 1, the carbonaceous substrate layer 11 has a higher thermal conductivity than the organic resin layer 20. Therefore, a multilayer substrate 1 with high heat dissipation properties is obtained.

[0017] Furthermore, in this multilayer substrate 1, the carbonaceous substrate layer 11 may have a larger volume fraction than the organic resin layer 20. Here, the volume fraction of the carbonaceous substrate layer 11 refers to the volume fraction of the carbonaceous substrate layer 11 among the components constituting the multilayer substrate 1. Similarly, the volume fraction of the organic resin layer 20 refers to the volume fraction of the organic resin layer 20 among the components constituting the multilayer substrate 1. When the volume of the carbonaceous substrate layer 11 is V1, the volume of the organic resin layer 20 is V2, and the combined volume of V1 and V2 is V0, the volume fraction of the carbonaceous substrate layer 11 (V1 / (V1+V2)) may have a value exceeding 0.5. By increasing the volume fraction of the carbonaceous substrate layer 11, which has a higher thermal conductivity than the organic resin layer 20, the heat dissipation properties of the multilayer substrate 1 can be maintained at a high level.

[0018] The organic resin layer 20 may also contain carbon particles located in the polymer material. In other words, the organic resin layer 20 may be a composite material in which a polymer material and carbon particles are combined. By containing the same chemical components as the adjacent carbonaceous substrate layer 11, the organic resin layer 20 improves the C-C bond strength when laminated, thereby improving the durability of the multilayer substrate 1. Note that the organic resin layer 20 may also contain inorganic particles such as silica and alumina in addition to the carbon particles.

[0019] Furthermore, the organic resin layer 20 may partially have voids 203. By having the voids 203, the volume ratio of the organic resin layer 20 in the multilayer substrate 1 is further reduced. This further improves the heat dissipation properties of the multilayer substrate 1. Here, the voids 203 have a shape or contour that corresponds to an open pore or a closed pore.

[0020] Furthermore, the organic resin layer 20 may have through-holes 204 in addition to the voids 203. Here, the through-holes 204 refer to spaces that penetrate between the surfaces 201 and 202 of the organic resin layer 20. This makes it difficult for heat to move in a lateral direction that intersects with the thickness direction of the organic resin layer 20, while facilitating heat movement toward the carbonaceous substrate layer 11, which has a higher thermal conductivity than the organic resin layer 20. This makes it possible to improve the heat dissipation properties of the multilayer substrate 1 in the thickness direction (stacking direction).

[0021] Comparing the sizes of the voids 203 and the through holes 204, when the average value of the maximum diameters of the voids 203 measured individually is set to 1, the maximum diameter of the through holes 204 may be approximately 10 to 10,000. Here, the maximum diameter of the through holes 204 may be defined as the larger of the maximum diameter of the space forming the through holes 204 or the maximum length of the organic resin layer 20 in the thickness direction.

[0022] Furthermore, when the organic resin layer 20 is divided into two equal parts in the thickness direction, the number frequency or volume of the voids 203 may be higher on one side in the thickness direction than on the other side. For example, assume that a heat-generating electrical element such as a semiconductor element is placed inside the through-hole 204. In such a case, it is preferable that the electrical element is located on the side of the organic resin layer 20 in the thickness direction where the number frequency or volume of the voids 203 is higher. Here, the volume refers to the total volume obtained by adding up the individual volumes of the multiple voids 203 contained in the volume of a specific portion of the organic resin layer 20.

[0023] Furthermore, it is preferable that the voids 203 exist so as to surround the through-holes 204 with a higher number frequency or volume than other regions. Here, the region that exists so as to surround the voids 203 with a higher number frequency or volume is defined as follows.

[0024] A region where the number frequency of voids 203 is high is a region where the number frequency is 1.5 or more when the number frequency of a region where the number frequency of voids 203 is low is 1. A region where the volume of voids 203 is high is a region where the volume of a region where the volume of voids 203 is low is 1.5 or more.

[0025] The multilayer substrate 1 may also have a metallic wiring layer 30 located on the surface 202, which is the surface of the organic resin layer 20. The multilayer substrate 1 may also have an insulating solder resist layer 40 that partially covers the surface of the wiring layer 30.

[0026] The multilayer substrate 1 may also have a mounting surface 103 on which an electric element is mounted. The mounting surface 103 is, for example, a portion of the surface 101 of the substrate 10 where the through-hole 204 of the organic resin layer 20 is located. The electric element may be, for example, a light-emitting element. The electric element may also be a heat source that generates heat when current is applied.

[0027] 1 shows a state in which the organic resin layer 20 is in contact with the carbonaceous substrate layer 11, but in this multilayer substrate 1, the organic resin layer 20 may be arranged such that part or all of it is separated from the carbonaceous substrate layer 11. In other words, the organic resin layer 20 may be located above the carbonaceous substrate layer 11.

[0028] Second Embodiment Fig. 2 is a cross-sectional view showing an example of a multilayer substrate according to a second embodiment. In this case, the multilayer substrate 1 shown as the second embodiment is also designated by the same reference numerals as the multilayer substrate 1 of the first embodiment shown in Fig. 1, as shown in Fig. 2. This is used for convenience because the multilayer substrate of the second embodiment is based on the multilayer substrate 1 of the first embodiment. The multilayer substrate 1 shown below is the multilayer substrate 1 according to the second embodiment.

[0029] 2, the multilayer substrate 1 may have an intermediate member layer 12. In this case, the intermediate member layer 12 is disposed between the carbonaceous substrate layer 11 and the organic resin layer 20. The intermediate member layer 12 may be, for example, a metal plate.

[0030] In the multilayer substrate 1, it is preferable that the carbonaceous substrate layer 11, the intermediate member layer 12, and the organic resin layer 20 are arranged in the stacking direction so that their thermal expansion coefficients increase in this order. Since the intermediate member layer 12, which has a thermal expansion coefficient between the carbonaceous substrate layer 11 and the organic resin layer 20, is located between them, it is possible to alleviate stress generated between the carbonaceous substrate layer 11 and the organic resin layer 20. It is also possible to reduce thermal deformation of the multilayer substrate 1 that occurs due to a sudden change in temperature.

[0031] The thermal expansion coefficients of the respective members constituting the multilayer substrate 1 preferably have the relationship (carbonaceous substrate layer 11) < (intermediate member layer 12) < (organic resin layer 20). Specific values ​​of the thermal expansion coefficients are, for example, 1×10 －６ / K or more 5×10 －６ / K or less, and the thermal expansion coefficient of the intermediate member layer 12 is 12×10 －６ / K or more 17×10 －６ / K or less, and the thermal expansion coefficient of the organic resin layer 20 is 22×10 －６ / K or more 30×10 －６ / K or less.

[0032] Furthermore, in the multilayer substrate 1, the carbonaceous substrate layer 11, the intermediate member layer 12, and the organic resin layer 20 may be arranged in such a manner that the thermal conductivity decreases in this order in the stacking direction. For example, when a heat-generating electrical element such as a light-emitting element is mounted on the organic resin layer 20 side, if a member with high thermal conductivity is positioned away from the electrical element, the carbonaceous substrate layer 11 side, which has a large surface area, will be largely exposed to the outside air. For this reason, heat is more easily dissipated from the carbonaceous substrate layer 11 side, which has a higher thermal conductivity than the organic resin layer 20. As a result, the multilayer substrate 1 can maintain high heat dissipation properties as a whole.

[0033] The thermal conductivity of each of the members constituting the multilayer substrate 1 preferably has the relationship (carbonaceous substrate layer 11) > (intermediate member layer 12) > (organic resin layer 20). Specific values ​​of the thermal conductivity may be, for example, the thermal conductivity of the carbonaceous substrate layer 11 may be 1500 W / m·K or more and 2000 W / m·K or less, the thermal conductivity of the intermediate member layer 12 may be 300 W / m·K or more and 500 W / m·K or less, and the thermal conductivity of the organic resin layer 20 may be 0.005 W / m·K or more and 3 W / m·K or less.

[0034] (Third Embodiment) Figure 3A is a cross-sectional view showing an example of a multilayer substrate according to a third embodiment. Figure 3B is a cross-sectional view taken along line A-A in Figure 3A. In this case, the same reference numerals as those used for the multilayer substrate 1 according to the first embodiment shown in Figure 1 and the multilayer substrate 1 according to the second embodiment shown in Figure 2 are used for the multilayer substrate 1 shown as the third embodiment. This is used for convenience, as the multilayer substrate according to the third embodiment is also based on the multilayer substrate 1 according to the first embodiment. The multilayer substrate 1 shown below is the multilayer substrate 1 according to the third embodiment.

[0035] The multilayer substrate 1 of the third embodiment shown in Figures 3A and 3B has a different through hole shape from the multilayer substrate 1 shown in Figure 2. As shown in Figures 3A and 3B, the through hole 204 formed in the multilayer substrate 1 of the third embodiment may have a hand-held drum shape. The shape of the through hole 204 here refers to the shape of the space provided in the organic resin layer 20.

[0036] 3A and 3B, the through-hole 204 will be described again. As shown in Figures 3A and 3B, the organic resin layer 20 constituting the multilayer substrate 1 of the third embodiment is divided into sections in a plan view.

[0037] In this case, for convenience, the right-hand portion of the organic resin layer 20 shown in Fig. 3B is referred to as the first organic resin layer part 20R, and the left-hand portion is referred to as the second organic resin layer part 20L. Also, the upper portion of the organic resin layer 20 shown in Fig. 3B is referred to as the third organic resin layer part 20U, and the lower portion of the organic resin layer 20 is referred to as the fourth organic resin layer part 20S.

[0038] 3A , the through hole 204 has a hand-drum shape, which means that the first organic resin layer part 20R and the second organic resin layer part 20L have protruding parts 205 on the through hole 204 side. Note that the organic resin layer 20 may have protruding parts 205 in the third organic resin layer part 20U and the fourth organic resin layer part 20S shown in FIG. 3B .

[0039] 3A and 3B , when the surfaces of the first organic resin layer part 20R, the second organic resin layer part 20L, the third organic resin layer part 20U, and the fourth organic resin layer part 20S constituting the organic resin layer 20 that are in contact with the through hole 204 are defined as inner walls 20W, the protruding parts 205 are portions of the inner walls 20W that protrude in a convex shape toward the through hole 204. In other words, the protruding parts 205 are portions that include the surfaces (inner walls 20W) that connect the surfaces 201 and 202 that constitute the organic resin layer 20.

[0040] In other words, when a line 20WL is connected between a connection point 20P1 between the surface 201 and the inner wall 20W and a connection point 20P2 between the surface 202 and the inner wall 20W, the protruding portion 205 is a portion that protrudes from the line 20WL toward the through hole 204. In the multilayer substrate 1, the protruding portion 205 is preferably formed so as to surround the periphery of the through hole 204. In other words, the first organic resin layer portion 20R, the second organic resin layer portion 20L, the third organic resin layer portion 20U, and the fourth organic resin layer portion 20S that constitute the organic resin layer 20 each have an inner wall 20W on the through hole 204 side, and the inner wall 20W is connected around the periphery of the through hole 204. The protruding portion 205 including the inner wall 20W of the through hole 204 may be disposed so as to extend from the first organic resin layer portion 20R, through the fourth organic resin layer portion 20S and the second organic resin layer portion 20L, to the third organic resin layer portion 20U. In this case, the protruding portion 205 is preferably integrated into the range extending from the first organic resin layer portion 20R, through the fourth organic resin layer portion 20S and the second organic resin layer portion 20L, to the third organic resin layer portion 20U.

[0041] Here, the opening diameter of the through hole 204 is formed so as to be smallest at any position in the thickness direction between the surface 201 and the surface 202. The opening diameter of the through hole 204 may be smallest at the center of the organic resin layer 20 in the thickness direction. The opening diameter of the through hole 204 at the surface 201 and the surface 202 may be the same or different. If the diameter at the surface 201 and the diameter at the surface 202 are different, the position of the apex of the protruding portion 205 in the thickness direction may be shifted toward either the surface 201 side or the surface 202 side. In this case, it is preferable that the position of the apex of the protruding portion 205 in the thickness direction be closer to the smaller diameter. Here, the diameter refers to the diameter (maximum diameter) at which the diameter value is largest when the diameter of the through hole 204 is measured.

[0042] For example, when a thermally conductive member such as a thermal interface material (TIM) is inserted into the through-hole 204, the inserted thermally conductive member tends to conform to the inner wall 20W of the through-hole 204. The protruding portion 205 makes it difficult for the thermally conductive member inside the through-hole 204 to come off to the outside. This ensures stable heat dissipation. For example, this multilayer substrate 1 can be suitably used in devices that are subject to large vibrations.

[0043] The protruding portion 205 may be located around the entire circumference of the through-hole 204 or may be located around only a portion of the circumference of the through-hole 204 .

[0044] (Fourth Embodiment) Fig. 4 is a cross-sectional view showing an example of a multilayer substrate according to a fourth embodiment. In this case, the same reference numerals as those of the multilayer substrate 1 of the first embodiment shown in Fig. 1 and the multilayer substrate 1 of the second embodiment shown in Fig. 2 are used for the multilayer substrate 1 shown as the fourth embodiment. This is used for convenience because the multilayer substrate of the fourth embodiment is also based on the multilayer substrate 1 of the first embodiment. The multilayer substrate 1 shown below is the multilayer substrate 1 according to the fourth embodiment. As shown in Fig. 4, in the multilayer substrate 1 of the fourth embodiment, the substrate 10 may include a second intermediate member layer 14 in addition to a first intermediate member layer 13.

[0045] The second intermediate member layer 14 may be located on the opposite side of the first intermediate member layer 13 with the carbonaceous substrate layer 11 sandwiched therebetween. The first intermediate member layer 13 may be located between the carbonaceous substrate layer 11 and the organic resin layer 20, and may be located on the surface 101 side of the substrate 10. The second intermediate member layer 14 may be located on the opposite side of the organic resin layer 20 with the first intermediate member layer 13 and the carbonaceous substrate layer 11 sandwiched therebetween. In other words, the second intermediate member layer 14 may be located on the surface 102 side of the substrate 10. The first intermediate member layer 13 and the second intermediate member layer 14 may be, for example, metal plates. By positioning the first intermediate member layer 13 and the second intermediate member layer 14 so as to sandwich the carbonaceous substrate layer 11 in this way, the rigidity of the carbonaceous substrate layer 11 can be increased, and the multilayer substrate 1 becomes less likely to deform. In this case, it is preferable that the elastic modulus (Young's modulus) of the first intermediate member layer 13 and the second intermediate member layer 14 be higher than the elastic modulus (Young's modulus) of the carbonaceous substrate layer 11.

[0046] The first intermediate member layer 13 and the second intermediate member layer 14 may have the same or different average thicknesses. Of the first intermediate member layer 13 and the second intermediate member layer 14, the thickness of the first intermediate member layer 13, on which the electrical elements are mounted, may be made thicker than the thickness of the second intermediate member layer 14. This is because the first intermediate member layer 13, on which the electrical elements are mounted, is more susceptible to thermal loads and deformation than the second intermediate member layer 14.

[0047] (Manufacturing Method) An example of a manufacturing method for the multilayer substrate 1 of the present disclosure will be specifically described below. Note that the present disclosure is not limited to the multilayer substrate 1 manufactured by the following manufacturing method.

[0048] First, a graphite sheet is prepared. Then, an uncured sheet of a thermosetting epoxy resin containing silica powder is prepared. The amount of silica powder added can be, for example, 150 parts by weight per 100 parts by weight of the epoxy resin.

[0049] Next, through holes (e.g., 500 μm square) are formed in the uncured sheet, and a wiring sheet is produced using this uncured sheet. The wiring sheet is, for example, an uncured sheet having a copper foil wiring pattern formed on one surface thereof by a transfer method. The wiring pattern is, for example, arranged in an area excluding the through holes. The copper foil wiring pattern used in the transfer method is, for example, a PET film with solid copper foil attached thereto, which is then patterned by etching.

[0050] The produced wiring sheet is placed on a graphite sheet and heated under pressure to obtain a base material for a multilayer substrate. The heating and pressurizing conditions can be, for example, a temperature of 200°C, a pressure of 0.1 MPa, and a heating time of 5 hours. The base material obtained is cut to a predetermined size to obtain a multilayer substrate. The same conditions as above can be used when a composite sheet of copper foil laminated on graphite is used instead of a graphite sheet.

[0051] For example, when manufacturing a multilayer substrate 1 having an organic resin layer 20 having a protruding portion 205 as shown in Figures 3A and 3B, the through hole 204 may be formed by setting the pressure conditions during the above-mentioned pressurizing and heating to a high value (e.g., 0.13 MPa).

[0052] Although the present disclosure has been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0053] In one embodiment, (1) the multilayer substrate has a carbonaceous substrate layer and an organic resin layer, the organic resin layer is located on the carbonaceous substrate layer, and the carbonaceous substrate layer has a higher thermal conductivity than the organic resin layer.

[0054] (2) In the multilayer substrate of (1) above, the carbonaceous substrate layer may have a volume fraction greater than that of the organic resin layer.

[0055] (3) The multilayer substrate of (1) or (2) may further include a first intermediate member layer, the first intermediate member layer being located between the carbonaceous substrate layer and the organic resin layer, and the thermal expansion coefficients of the carbonaceous substrate layer, the first intermediate member layer, and the organic resin layer may increase in this order.

[0056] (4) In the multilayer substrate of (3) above, the thermal conductivity of the carbonaceous substrate layer, the first intermediate member layer, and the organic resin layer may decrease in this order.

[0057] (5) In the multilayer substrate of any one of (1) to (4) above, the organic resin layer may have a void.

[0058] (6) The multilayer substrate of (5) above may further have through holes.

[0059] (7) In the multilayer substrate of (6) above, the through hole may have a hand-held drum shape.

[0060] (8) The multilayer substrate according to (3) or (4) may further include a second intermediate member layer, and the second intermediate member layer may be located on a surface of the carbonaceous substrate layer opposite to a surface on which the first intermediate member layer is located.

[0061] (9) In the multilayer substrate of any one of (1) to (8) above, the main material of the carbonaceous substrate layer may be graphite.

[0062] (10) In the multilayer substrate of any one of (1) to (9) above, the organic resin layer may contain a polymer material and carbon particles.

[0063] Further advantages and other aspects may readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0064] REFERENCE SIGNS LIST 1 multilayer substrate 10 substrate 11 carbonaceous substrate layer 12 intermediate member layer 13 first intermediate member layer 14 second intermediate member layer 20 organic resin layer 30 wiring layer 203 void portion 204 through hole

Claims

1. A carbonaceous substrate layer and an organic resin layer are included. the organic resin layer is located on the carbonaceous substrate layer, The carbonaceous substrate layer has a higher thermal conductivity than the organic resin layer. Multilayer board.

2. The carbonaceous substrate layer has a larger volume fraction than the organic resin layer. The multilayer substrate according to claim 1 .

3. a first intermediate member layer; the first intermediate member layer is located between the carbonaceous substrate layer and the organic resin layer, The thermal expansion coefficients of the carbonaceous substrate layer, the first intermediate member layer, and the organic resin layer increase in this order. The multilayer substrate according to claim 1 or 2.

4. The thermal conductivity of the carbonaceous substrate layer, the first intermediate member layer, and the organic resin layer decreases in this order. The multilayer substrate according to claim 3 .

5. The organic resin layer has voids. The multilayer substrate according to claim 1 or 2.

6. The organic resin layer further has through holes. The multilayer substrate according to claim 5 .

7. The through-hole has a drum-like shape. The multilayer substrate according to claim 6 .

8. a second intermediate member layer; The second intermediate member layer is located on a surface of the carbonaceous substrate layer opposite to a surface on which the first intermediate member layer is located. The multilayer substrate according to claim 3 .

9. The main material of the carbonaceous substrate layer is graphite. The multilayer substrate according to claim 1 or 2.

10. The organic resin layer contains a polymer material and carbon particles. The multilayer substrate according to claim 1 or 2.