JP2007165751A - Wiring board, and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board for sufficiently achieving the insulation property of a substrate surface and the radiation property of the wiring board. <P>SOLUTION: An alumite layer 2 as a metal oxide insulating layer is formed on the surface of an aluminum substrate 1 as a metal board, and a heat conductive resin insulating layer 3 is formed on the surface of the alumite layer 2 at the opposite side of the aluminum substrate 1, and a wiring section 7 is formed on the surface of the heat conductive resin insulating layer 3 at the opposite side of the alumite layer 2. Then, the alumite layer 2 is provided with recesses 4a and 4b of at least one type of a hole and a crack on the surface, and the heat conductive resin insulating layer 3 is formed in such a status that it enters the recesses 4a and 4b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring board and a manufacturing method thereof.

  In order to mount high heat-generating components in high density in recent years, high heat dissipation is required for the wiring board on which the components are mounted. Moreover, in order to implement | achieve the function of a wiring board, the surface of the board | substrate with which a wiring part is distribute | arranged needs to be comprised with the insulator. Therefore, conventionally, as a means for obtaining a wiring board with good heat dissipation, a technique of arranging an organic polymer material as an insulator on the surface of an aluminum substrate is known. However, the organic polymer material has low thermal conductivity, and the heat dissipation of the wiring board is not sufficient. Therefore, a technique for including metal particles coated with a metal oxide in the organic polymer material has been proposed (see Patent Document 1).

JP 59-204296 A

  However, it is known that metal oxides such as alumite are likely to crack due to temperature changes. For this reason, the metal particles are exposed due to the occurrence of cracks, and there is a problem that the insulating property of the substrate surface cannot be maintained for a long time.

  Therefore, the problem to be solved by the present invention is to provide a wiring board that sufficiently realizes the insulation of the substrate surface and the heat dissipation of the wiring board.

  In order to solve the above problems, the wiring board according to the present invention has a metal oxide insulating layer formed on the surface of a metal substrate, and a thermally conductive resin insulating layer on the surface of the metal oxide insulating layer opposite to the metal substrate. A wiring board formed and having a wiring portion formed on a surface opposite to the metal oxide insulating layer of the thermally conductive resin insulating layer, wherein the metal oxide insulating layer has at least one of holes and cracks on the surface thereof The heat conductive resin insulation layer is formed in a state of entering into the recess.

  According to the wiring board of the present invention, since the metal oxide insulating layer and the heat conductive resin insulating layer having high thermal conductivity are arranged on the surface of the metal substrate, the metal substrate has sufficient heat dissipation characteristics. You can save it. In addition, since the metal oxide insulating layer has a recess, and the heat conductive resin insulating layer is formed in a state of entering into the surface vacant portion, the heat conductive resin insulating layer is made of the metal oxide insulating layer. It will be structurally reinforced. Therefore, it is possible to suppress the formation of a new crack in the metal oxide insulating layer due to a temperature change or the like, and it is possible to maintain the insulating property of the metal substrate surface. Moreover, since the air in a recessed part decreases by the penetration | invasion in the recessed part of a heat conductive resin insulating layer, it can further suppress that the water | moisture content in the air reduces the insulation of a metal oxide insulating layer. In addition, when a crack is formed in the metal oxide insulating layer in advance and the resin enters the recess due to the crack, the stress is relaxed there, so that it is difficult to form a new crack when the temperature changes.

  In another wiring board according to the present invention, in addition to the above-described invention, the metal substrate is made of aluminum or an aluminum-based alloy, and the metal oxide insulating layer is made of alumite. By adopting this configuration, the weight of the metal substrate can be reduced, and the metal oxide insulating layer can be formed by simple means such as anodization of the metal substrate.

  In addition to the above-described invention, another wiring board according to the present invention uses alumite as hard alumite. Since hard anodized metal with high hardness is less likely to form cracks due to temperature changes, it is possible to further suppress the deterioration of the insulating properties of the metal substrate. Here, hard anodized refers to anodized having a hardness of 250 HV or higher. In addition, the hardness is obtained by measuring an alumite layer portion in a cross section of an aluminum substrate with an alumite layer with a load of 100 g using a micro Vickers hardness meter (hereinafter, the hardness is determined by the same measurement method). is there).

  In addition to the above-described invention, the wiring board according to another aspect of the present invention has a thickness of the heat conductive resin insulating layer in a range of 5 μm or more and 50 μm or less except for a portion that enters the recess. When the thickness of the heat conductive resin insulating layer is 5 μm or more, the insulating property of the metal substrate surface is further increased. Moreover, when the thickness of the heat conductive resin insulating layer is 50 μm or less, the heat dissipation of the wiring board is further increased.

  In addition to the above-described invention, the wiring board according to another embodiment of the present invention has the metal substrate surface exposed to the recesses oxidized. By adopting this configuration, it is possible to prevent the conductivity of the surface of the metal substrate exposed in the recess and to improve the insulation of the surface of the metal substrate.

  In addition to the above-described invention, in another wiring board according to the present invention, a part of the wiring portion passes through the thermally conductive resin insulating layer and is in contact with the metal oxide insulating layer. By adopting this configuration, most of the Joule heat generated in the wiring section or the heat transferred from the highly heat-generating electronic component to the wiring section is directly applied to the metal oxide insulating layer without interposing a heat conductive resin insulating layer. The heat dissipation of the wiring board can be made better.

  In order to solve the above problems, a method of manufacturing a wiring board according to the present invention includes a first step of forming a metal oxide insulating layer on a surface of a metal substrate, and a surface of the metal oxide insulating layer opposite to the metal substrate. A wiring board having a second step of forming a heat conductive resin insulating layer on the surface and a third step of forming a wiring portion on the surface of the heat conductive resin insulating layer opposite to the metal oxide insulating layer. In the production method, the second step is a step of curing the resin in a state in which the liquid resin is infiltrated into at least one kind of recesses in the pores and cracks on the surface of the metal oxide insulating layer, Alternatively, it is a step of curing the resin in a state where the fluid resin is pressed into the recess.

  According to the method for manufacturing a wiring board according to the present invention, the thermally conductive resin insulating layer can be formed in the recessed portion of the metal oxide insulating layer in the second step. Therefore, the heat conductive resin insulating layer structurally reinforces the metal oxide insulating layer. Therefore, it is possible to suppress the formation of cracks in the metal oxide insulating layer due to a temperature change or the like, and it is possible to maintain the insulating property of the metal substrate surface. Moreover, since the moisture in the air in the recess is reduced due to the heat conductive resin insulating layer entering the recess, it is possible to further suppress the moisture from lowering the insulating property of the metal oxide insulating layer. Furthermore, since the metal oxide insulating layer and the heat conductive resin insulating layer having high thermal conductivity are arranged on the surface of the metal substrate, the wiring board can sufficiently utilize the characteristics of heat dissipation that the metal substrate has.

  In another aspect of the present invention, in addition to the above-described method for manufacturing a wiring board, when the recess includes the crack, the crack is formed in the metal oxide insulating layer after the first step and before the second step. I am going to do that. By adopting this configuration, it is possible to form a crack in the metal oxide insulating layer formed in the first step in advance and relieve stress. Therefore, new cracks are hardly formed even when the temperature changes. In this state, since the thermally conductive resin insulating layer is inserted into the crack (recessed portion) by the second step, the insulation deterioration due to the exposure of the metal substrate in the recessed portion is suppressed.

  In another aspect of the present invention, in addition to the above-described method for manufacturing a wiring board, the third step includes a step of arranging a metal foil having a profile on the resin surface or the surface of the thermally conductive resin insulating layer. In addition, the profile of the metal foil has undergone a process of passing through the resin or the heat conductive resin insulating layer and contacting the metal oxide insulating layer. By adopting this configuration, most of the Joule heat generated in the wiring section or the heat transferred from the highly heat-generating electronic component to the wiring section is directly applied to the metal oxide insulating layer without interposing a heat conductive resin insulating layer. The heat dissipation of the wiring board can be made better.

  According to the present invention, it is possible to provide a wiring board that sufficiently realizes insulation on the surface of the substrate and heat dissipation of the wiring board.

(First embodiment)
First, the wiring board 10 and its manufacturing method according to the first embodiment will be described with reference to FIG. 1 showing an example of the manufacturing process and FIG. 2 showing the flow of the manufacturing process. In FIG. 1, the manufacture of the wiring board 10 proceeds as the process proceeds from (A) to (D).

  As shown in FIG. 1D, the wiring board 10 of the first embodiment has an alumite layer 2 as a metal oxide insulating layer formed on the surface of an aluminum substrate 1 as a metal substrate. A heat conductive resin insulating layer 3 is formed on the surface opposite to the aluminum substrate 1, and a wiring portion 7 is formed on the surface of the heat conductive resin insulating layer 3 opposite to the anodized layer 2. And the alumite layer 2 has the recessed part 4a which consists of a void | hole part in the whole region including the surface, and the heat conductive resin insulation layer 3 is formed in the state penetrated in the recessed part 4a.

  As shown in FIG. 2, the manufacturing method of the wiring board 10 according to the first embodiment is a first step of forming an alumite layer 2 as a metal oxide insulating layer on the surface of an aluminum substrate 1 as a metal substrate ( Step S101), a second step (Step S102) of forming the heat conductive resin insulation layer 3 on the surface of the alumite layer 2 opposite to the aluminum substrate 1, and the alumite layer 2 of the heat conductive resin insulation layer 3 And a third step (step S103) for forming the wiring part 7 on the opposite surface. The second step is a step of curing the resin 5 in a state where the liquid resin 5 is infiltrated into the concave portion 4a formed of pores on the surface of the alumite layer 2, or the fluid resin 5 is alumite layer 2 This is a step of curing the resin 5 in a state of being press-fitted into the recess 4a.

  FIG. 1A shows an aluminum substrate 1. Here, the aluminum substrate 1 is made of metal aluminum or an aluminum-based alloy. Suitable aluminum-based alloys include, for example, Al-Cu alloys, Al-Mn alloys, Al-Si alloys, Al-Mg alloys, Al-Mg-Si alloys, Al-Zn-Mg alloys, etc. Can be used.

  FIG. 1B shows a state in which an alumite layer 2 having a thickness of 20 μm is formed on one surface of the aluminum substrate 1. The alumite layer 2 is formed by anodizing one surface of the aluminum substrate 1 in a phosphoric acid bath. Such a process corresponds to the first process. The formed alumite layer 2 is so-called phosphoric acid alumite having a hardness of less than 250 HV. The alumite layer 2 has a concave portion 4a composed of a hole portion in the entire region including the surface thereof. In order to adjust the thickness of the alumite layer 2, for example, the amount of electricity and the oxidation time during the anodic oxidation may be appropriately adjusted.

  FIG. 1C shows a state in which a liquid resin 5 is disposed on the surface of the alumite layer 2 formed in the first step by a coating means such as spin coating or curtain coating. The resin 5 penetrates into the recess 4a. In this state, the resin 5 is cured by heat treatment to obtain the heat conductive resin insulating layer 3. As a result, the heat conductive resin insulation layer 3 is in a state where it enters into the recess 4a formed of a hole in the surface of the alumite layer 2. This process corresponds to the second process.

  Here, as the resin 5, an insulating resin used for a printed circuit board such as a commercially available polyimide resin or epoxy resin, or a resin in which a filler is mixed into these resins can be suitably used. Moreover, in order to implement | achieve the high heat conductivity (heat dissipation) of the heat conductive resin insulation layer 3, it is good to make the thickness thin. The preferred thickness varies depending on the material to be used, but is generally 50 μm or less except for the portion that has entered the recess 4a. Further, the insulating property of the heat conductive resin insulating layer 3 can be realized by not reducing the thickness of the heat conductive resin insulating layer 3 or mixing conductive particles or the like. A suitable thickness varies depending on the material to be used, but is approximately 5 μm or more except for a portion entering the recess 4a. However, when the insulation of the surface of the aluminum substrate 1 can be sufficiently secured by increasing the thickness of the alumite layer 2 or by using hard alumite, etc., the thickness of the heat conductive resin insulation layer 3 is set to the concave portion 4a. It is preferable that the thickness is 1 μm, 2 μm, 3 μm, or 4 μm except for the portion that enters the inside. The thickness of the heat conductive resin insulation layer 3 according to the first embodiment is set to 5 μm except for the portion that enters the recess 4a.

  An adhesive resin sheet can be used as the resin 5. By sticking the adhesive resin sheet on the surface of the alumite layer 2 and pressing from above the adhesive resin sheet, the resin 5 can be pressed into the recess 4a. Here, the resin 5 that can be press-fitted into the recess 4a is a resin 5 having fluidity. Thereafter, when the resin 5 is cured by heat treatment, the thermally conductive resin insulation layer 3 in a state of entering the recess 4a can be obtained. From the viewpoint of ensuring higher insulation on the surface of the aluminum substrate 1, as shown in FIG. 1, the heat conductive resin insulation layer 3 is formed in the recess 4a so as to cover the surface of the aluminum substrate 1 exposed in the recess 4a. It is preferable to penetrate into the whole area.

  As described above, when the thermally conductive resin insulation layer 3 enters only at least the vicinity of the entrance of the recess 4a (preferably, enters the entire area of the recess 4a), the thermally conductive resin insulation layer 3 becomes an alumite layer. 2 will be structurally reinforced. Therefore, it can suppress that a further crack is formed in the alumite layer 2 by a temperature change etc., As a result, the insulation of the aluminum substrate 1 surface can be maintained for a long period of time. Moreover, since the air in the recessed part 4a will decrease if it will be in said state, the insulation fall of the aluminum substrate 1 surface resulting from the water | moisture content in the air can further be suppressed. Furthermore, the adhesiveness between the heat conductive resin insulation layer 3 and the alumite layer 2 becomes strong, and the heat conductive resin insulation layer 3 is hardly peeled off due to thermal contraction or expansion of the heat conductive resin insulation layer 3.

  FIG. 1D shows a state in which the wiring portion 7 is formed on the heat conductive resin insulating layer 3. The wiring part 7 is formed by a means for arranging a copper foil for wiring on the thermally conductive resin insulation layer 3 and thereafter removing portions other than the wiring pattern by etching. This step corresponds to the third step. The wiring board 10 according to the first embodiment is completed through the above steps.

(Second Embodiment)
Next, the wiring board 11 and its manufacturing method according to the second embodiment will be described with reference to FIG. 3 showing an example of the manufacturing process. In FIG. 3, the manufacture of the wiring board 10 progresses from (A) to (E).

  As shown in FIG. 3E, the wiring board 11 of the second embodiment has an alumite layer 2 as a metal oxide insulating layer formed on the surface of an aluminum substrate 1 as a metal substrate. A heat conductive resin insulating layer 3 is formed on the surface opposite to the aluminum substrate 1, and a wiring portion 7 is formed on the surface of the heat conductive resin insulating layer 3 opposite to the anodized layer 2. The alumite layer 2 has a concave portion 4a composed of a hole and a concave portion 4b composed of a crack over the entire surface including the surface thereof, and the thermally conductive resin insulating layer 3 is formed in a state of entering at least the concave portions 4a and 4b. Has been.

  The manufacturing method of the wiring board 11 of the second embodiment is such that cracks are formed in the alumite layer 2 after the first step (step S101) shown in FIG. 2 and before the second step (step S102) shown in FIG. The manufacturing method of the wiring board 11 according to the first embodiment is the same as that of the first embodiment except that the forming step is included.

  3A and 3B show the same contents as those in FIGS. 1A and 1B in the first embodiment. FIG. 3C shows a state in which cracks are formed in the alumite layer 2. For example, the formation of the crack is performed by one cycle consisting of heating up to about 270 ° C., which is higher than the assumed use temperature of the wiring board 11, and then rapidly cooling into water at room temperature (about 20 ° C.). It is performed by repeating as necessary two or more times.

  FIG. 3D shows a state in which the liquid resin 5 is arranged on the surface of the alumite layer 2 by the same means as in the first embodiment. The resin 5 penetrates into the recesses 4a and 4b. In this state, the resin 5 is cured by heat treatment to obtain the heat conductive resin insulating layer 3. As a result, the heat conductive resin insulation layer 3 enters the recesses 4 a and 4 b of the alumite layer 2. The thickness of the heat conductive resin insulation layer 3 is set to 5 μm except for the portion that has entered the recess 4a as in the first embodiment.

  FIG. 3E shows the same contents as FIG. 1D in the first embodiment. In the wiring board 11 of the second embodiment obtained by the above steps, in addition to the effects obtained by the wiring board 10 of the first embodiment, the stress at the time of temperature change is relieved by the formation of cracks. Therefore, it is difficult to form new cracks, and further, the insulation of the surface of the aluminum substrate 1 can be realized.

(Third embodiment)
Next, the wiring board 12 and its manufacturing method according to the third embodiment will be described with reference to FIG. 4 showing an example of the manufacturing process. In FIG. 4, as the process proceeds from (A) to (F), the manufacture of the wiring board 12 proceeds.

  In the wiring board 12 of the third embodiment, as shown in FIG. 4F, the wiring portion 7 is constituted by a wiring copper foil 6 that is a metal foil, and forms a part of the wiring copper foil 6. The profile 8 is configured to pass through the heat conductive resin insulation layer 3 and to contact the alumite layer 2.

  The method for manufacturing the wiring board 12 according to the third embodiment is a metal foil having a profile 8 on the surface of the resin 5 in the third step of the method for manufacturing the wiring board 11 according to the second embodiment. The wiring according to the second embodiment has a process of arranging the copper foil 6 and the profile 8 of the wiring copper foil 6 passes through the resin 5 and is brought into contact with the alumite layer 2 which is a metal oxide insulating layer. Different from the manufacturing method of the plate 11. In the third step, a copper foil 6 for wiring having a profile 8, which is a metal foil, is disposed on the surface of the resin 5, and the profile 8 of the copper foil 6 for wiring passes through the resin 5 and contacts the alumite layer 2. At the same time or after that, the resin 5 is cured to form the heat conductive resin insulating layer 3. Thus, the second step is completed during the third step. Then, the wiring part 7 is obtained through the process of etching the copper foil 6 for wiring, and a 3rd process is complete | finished.

  4 (A), (B), and (C) have the same contents as those in FIGS. 3 (A), (B), and (C) in the second embodiment, and thus description thereof is omitted. At the stage of FIG. 4D, since the resin 5 is not cured, the heat conductive resin insulation layer 3 is not completely formed, and the second step has not been completed yet. FIG. 4E shows a state in which the wiring copper foil 6 having the profile 8 is arranged on the resin 5 in a state where the resin 5 is not completely cured.

  Next, the copper foil for wiring 6 having the profile 8 is heated and pressed from above the resin 5 and the copper foil for wiring 6 so as to pass through the resin 5 that has not been completely cured and contact the alumite layer 2. Then, as shown in FIG. 4F, the profile 8 of the wiring copper foil 6 passes through the resin 5 and comes into contact with the alumite layer 2. Further, the resin 5 is cured by the heat press to form the heat conductive resin insulating layer 3, and the second step is completed. Thereafter, the wiring portion 7 is formed by means for removing portions other than the wiring pattern of the wiring copper foil 6 by etching. Thus, the third step is completed.

  The wiring board 12 of the third embodiment obtained by the above steps is obtained by the wiring board 11 of the second embodiment because the profile 8 of the wiring copper foil 6 is in direct contact with the alumite layer 2. In addition to the effect obtained, most of the Joule heat generated in the wiring part 7 or the heat transferred from the highly heat-generating electronic component to the wiring part 7 is directly applied to the alumite layer 2 without interposing the heat conductive resin insulating layer 2. I can escape. Therefore, the heat dissipation of the wiring board 12 can be made better.

  The alumite layer 2 according to the first, second and third embodiments is made of phosphoric alumite formed by anodizing the aluminum substrate 1 in a phosphoric acid solution. However, other electrolytic baths such as a phosphoric acid solution, a sulfuric acid solution, an oxalic acid solution, a citric acid solution, an aromatic sulfonic acid solution, a chromic acid solution, a mixed solution of these two or more may be appropriately selected and used. it can. The formed alumite layer 2 can be made of so-called golden alumite, white alumite, chromic alumite, or the like. In addition, when forming hard anodized different from golden anodized, phosphoric anodized, white anodized, chromic anodized, etc. as the anodized layer 2, the temperature and concentration of these electrolytic baths and the current density to be energized are appropriately adjusted. Good. Since hard anodized metal having high hardness is less likely to form cracks due to temperature changes, it is possible to further suppress the deterioration of the insulating properties of the aluminum substrate 1. From the viewpoint of suppressing crack formation, the hardness of the hard alumite is preferably 300 HV or higher, more preferably 350 HV or higher, and even more preferably 400 HV or higher.

  To form hard alumite, the electrolytic bath temperature should be around 0 ° C., and the current density should be higher than when ordinary alumite (golden alumite, phosphate alumite, white alumite, chromate alumite, etc.) is formed. good. When the current density is increased, a thick alumite layer can be formed efficiently. When the current density is high, large Joule heat is generated at the interface between the aluminum substrate 1 and the electrolytic bath, and the electrolytic bath temperature at the interface may be high. In such a case, the electrolytic bath may be stirred with a stirring blade or the like as necessary. When such a forming method is employed, an alumite layer can be formed more easily and efficiently than ordinary alumite.

Hereinafter, suitable examples of the method for forming hard anodized will be shown. When sulfuric acid is used for the electrolytic bath, the sulfuric acid concentration is 10 to 20 mol%, the electrolytic bath temperature is 0 to 10 ° C., and the current density is 2 to 5 A / dm ² . When oxalic acid is used for the electrolytic bath, the oxalic acid concentration is 3 to 8 mol%, the electrolytic bath temperature is 5 to 15 ° C., and the current density is 2 to 10 A / dm ² . Further, when a mixed solution of sulfuric acid and oxalic acid is used for the electrolytic bath, the sulfuric acid concentration is 10 to 20 mol%, the oxalic acid concentration is 1 to 2 mol%, the electrolytic bath temperature is 0 to 15 ° C. The current density is 2 to 5 A / dm ² .

  In addition, since the surface of hard anodized is relatively hard, it is difficult to be damaged by an impact caused by scratching with a fixing jig for a wiring board when mounting an electronic component, and the insulation of the surface of the aluminum substrate 1 is unlikely to deteriorate. Have advantages.

  In the first, second, and third embodiments, normal sealing treatment by a method of melting and recrystallizing (regrowing) the alumite layer 2 itself is not performed. The reason is that since a state in which the heat conductive resin insulating layer 3 enters the recesses 4a and 4b is formed, the same result as that obtained when the so-called sealing treatment is performed can be obtained. However, you may form the heat conductive resin insulation layer 3 after performing a normal sealing process. Thereby, the insulation of the surface of the aluminum substrate 1 can be further improved. As a normal sealing method, for example, a method in which the alumite layer 2 is immersed in a nickel acetate solution, a method in which the alumite layer 2 is brought into contact with the vapor of the nickel acetate solution, a steam sealing with pressurized steam capable of imparting high corrosion resistance, Examples thereof include dichromic acid sealing capable of imparting corrosion resistance without significantly reducing the wear resistance, or low-temperature sealing with fluoride. As a result of such normal sealing treatment, the surface of the aluminum substrate 1 exposed to or equivalent to being exposed in the recesses 4a and 4b can be protected, and the relatively brittle anodized Even layer 2 can be reinforced.

  In the first, second, and third embodiments, the metal oxide insulating layer is formed on one surface of the metal substrate. However, a metal oxide insulating layer may be formed on both sides of the metal substrate. In that case, it is possible to obtain a wiring board (double-sided wiring board) in which wiring parts capable of mounting electronic components are arranged on both surfaces of the metal substrate. In the double-sided wiring board, when the substrate has a through hole, a metal oxide insulating layer and / or a thermally conductive resin insulating layer can be formed on the inner wall surface of the through hole.

  In the first, second, and third embodiments, the heat conductive resin insulating layer is used. However, if the insulating property of the metal oxide insulating layer is sufficiently high, the heat conductive resin insulating layer is used. Is not necessarily required. If the heat conductive resin insulation layer is not provided, the heat dissipation of the wiring board becomes better. For example, as a first means for that purpose, a recess 4b made of a crack is formed in advance in the metal oxide insulating layer as in the second and third embodiments, and a metal substrate exposed in the recess 4b is described later. An oxidation treatment is performed to ensure the insulation of the exposed part. In this case, the crack is preferably given a thermal stress by a temperature change larger than a temperature change that can be assumed when the wiring board is used, so that the stress relaxation of the alumite layer 2 is sufficiently performed. The second means uses a metal oxide insulating layer, such as hard alumite, which is unlikely to crack due to temperature changes. In that case, the hardness of the metal oxide insulating layer is preferably 300 HV or more.

  It is preferable that the metal substrate surface exposed to the concave portions 4a and 4b formed of the voids or cracks of the metal oxide insulating layer is oxidized by means such as heat treatment in air or re-anodizing treatment. The reason for this is to prevent the conductivity due to the metal substrate surface exposed in the recesses 4a and 4b, and to further improve the insulation of the metal substrate surface. Here, when the oxidation treatment by anodic oxidation is performed again, the surface of the metal oxide insulating layer is closer to the cathode than the surface of the metal substrate exposed in the recesses 4a and 4b. Oxidized preferentially, the exposed metal substrate surface may not be easily oxidized. In that case, the energized voltage can be made smaller than when the metal oxide insulating layer is formed, and the anodic oxidation can be performed slowly, thereby relaxing the concentration of the oxidized region and promoting the oxidation of the exposed metal substrate surface. preferable.

  In the third step according to the first, second and third embodiments, the wiring portion 7 is formed by a so-called subtractive method, but the wiring portion 7 is formed by a so-called additive method (semi-additive, full-additive, etc.). Can also be formed.

  In the third embodiment, a part of the wiring portion 7 is configured to pass through the heat conductive resin insulating layer 3 and to be in contact with the alumite layer 2. This configuration can also be realized by means other than the method for manufacturing the wiring board 12 according to the third embodiment. For example, the surface of the copper foil 6 for wiring, which is a metal foil constituting the wiring portion 7, is roughened on the side in contact with the heat conductive resin insulating layer 3, and the convex portion of the rough surface passes through the resin before curing. This can be realized by means for curing the resin after contacting the metal oxide insulating layer. Here, as a means for roughening the metal foil, for example, the metal foil is immersed in an etching solution, the metal foil is partially melted by laser irradiation, or mechanically partially ground with a file or the like. Etc. Further, the commercially available copper foil for wiring 6 is preliminarily subjected to a profile process called a “cobb process” in order to improve the adhesive strength with the resin, and this can also be used. Further, when the wiring part 7 is formed by the additive method, a means for forming a hole that leads to the metal oxide insulating layer in the heat conductive resin insulating layer 3 and filling the hole is also preferable. It is. Furthermore, in the method of manufacturing the wiring board 12 according to the third embodiment, after the resin 5 is cured or after being cured to the extent that does not hinder circuit processing such as etching, the thermally conductive resin insulation layer 3 and The profile 8 of the wiring copper foil 6 may pass through the heat conductive resin insulation layer 3 and be in contact with the alumite layer 2 by means such as pressing from above the wiring copper foil 6. .

  In the first, second, and third embodiments, the aluminum substrate 1 is used as the metal substrate, the metal oxide insulating layer is the alumite layer 2, and the wiring portion 7 is made of the copper foil 6 for wiring. It is not limited to these combinations. For example, a stainless steel plate, a zinc copper plate, a silicon copper plate, or the like can be used for the metal substrate, and the metal oxide insulating layer can be an alumina ceramic layer or the like. In place of the metal oxide insulating layer, a metal nitride layer such as an aluminum nitride layer having good heat dissipation may be used. The wiring part 6 can be made of a conductive resin such as a conductive adhesive provided with conductivity by silver powder, thick copper having a thickness of 300 μm or more with good heat dissipation, and the like. Here, an alumina ceramic plate having no surface voids is pasted on the stainless steel substrate surface, a crack is formed in the alumina ceramic plate, and then the heat conductive resin insulation layer 3 is formed so as to enter the crack, and then heat conduction is performed. By forming the wiring portion 7 on the surface of the conductive resin insulating layer 3 opposite to the alumina ceramic plate, the conductive resin insulating layer 3 has only the concave portion 4b made of cracks without the concave portion 4a made of holes on the surface of the metal oxide insulating layer. A wiring board can be constituted.

  In the first, second and third embodiments, a polyimide resin or an epoxy resin is used as the heat conductive resin insulating layer 3, but it is not limited thereto. For example, in order to improve heat dissipation, it is possible to use a material mixed with aluminum nitride powder, aluminum oxide powder or the like excellent in thermal conductivity, polyamideimide resin, bismaleide triazine resin or the like excellent in heat resistance.

  In the second and third embodiments, the means for forming a crack in the metal oxide insulating layer is a means for applying a thermal stress (thermal shock) of a temperature change larger than a temperature change that can be assumed when the wiring board is used. Yes. This means is preferable in that cracks are formed in advance at locations that would be formed by the use of the wiring board, so that new cracks are extremely difficult to form when the wiring board is actually used. However, other means for forming cracks, for example, means for applying a mechanical impact can be employed. Even with this mechanical impact, cracks are preferentially formed at the locations where the stress is to be relieved, and the same result as the application of thermal stress can be obtained.

It is a figure which shows the manufacturing method of the wiring board which concerns on 1st Embodiment, (A) shows an aluminum substrate, (B) shows the state which formed the alumite layer in one surface of the aluminum substrate, (C ) Shows a state in which a thermally conductive resin insulating layer is formed on the alumite layer and in the surface hole portion, and (D) shows a state in which a wiring portion is formed on the thermally conductive resin insulating layer. It is a flowchart which shows the flow of the manufacturing process of the wiring board which concerns on 1st Embodiment. It is a figure which shows the manufacturing method of the wiring board which concerns on 2nd Embodiment, (A) shows an aluminum substrate, (B) shows the state which formed the alumite layer in one surface of the aluminum substrate, (C ) Shows a state in which a crack is formed in the alumite layer, (D) shows a state in which a thermally conductive resin insulating layer is formed on the alumite layer, in the surface vacancy portion, and in the crack, and (E) shows a thermal conductivity. The state which formed the wiring part on the resin insulating layer is shown. It is a figure which shows the manufacturing method of the wiring board which concerns on 3rd Embodiment, (A) shows an aluminum substrate, (B) shows the state which formed the alumite layer in one surface of the aluminum substrate, (C ) Shows a state in which a crack is formed in the alumite layer, (D) shows a state in which a liquid resin is arranged on the alumite layer, in the surface pores, and in the crack, and (E) shows that the liquid resin is completely Shows a state in which the wiring part is formed on the resin at a stage where it is not cured, and (F) shows a state in which the profile of the wiring copper foil of the wiring part passes through the resin and contacts the alumite layer.

Explanation of symbols

1 Aluminum substrate (metal substrate)
2 Anodized layer (metal oxide insulating layer)
3 Thermally conductive resin insulating layer 4a Recessed portion (recessed portion formed of surface pores of anodized layer)
4b Concavity (concave consisting of cracks in anodized layer)
5 Resin 6 Copper foil for wiring 7 Wiring part 8 Profile 10, 11, 12 Wiring board

Claims (9)

A metal oxide insulating layer is formed on the surface of the metal substrate, a thermally conductive resin insulating layer is formed on the surface of the metal oxide insulating layer opposite to the metal substrate, and the metal of the thermally conductive resin insulating layer In the wiring board in which the wiring part is formed on the surface opposite to the oxide insulating layer,
The metal oxide insulating layer has a concave portion of at least one of holes and cracks on the surface thereof, and the thermally conductive resin insulating layer is formed in a state of entering the concave portion. A characteristic wiring board.   2. The wiring board according to claim 1, wherein the metal substrate is made of aluminum or an aluminum-based alloy, and the metal oxide insulating layer is made of alumite.   The wiring board according to claim 2, wherein the alumite is hard alumite.   4. The wiring board according to claim 1, wherein a thickness of the heat conductive resin insulating layer is in a range of 5 μm or more and 50 μm or less excluding a portion entering the concave portion. 5.   5. The wiring board according to claim 1, wherein the metal substrate surface exposed to the recess is subjected to an oxidation treatment. 6.   6. The wiring board according to claim 1, wherein a part of the wiring portion is in contact with the metal oxide insulating layer through the thermally conductive resin insulating layer. . A first step of forming a metal oxide insulating layer on the surface of the metal substrate; a second step of forming a thermally conductive resin insulating layer on the surface of the metal oxide insulating layer opposite to the metal substrate; A third step of forming a wiring portion on the surface of the thermally conductive resin insulating layer opposite to the metal oxide insulating layer,
The second step is a step of curing the resin in a state in which a liquid resin is infiltrated into at least one kind of recesses of holes and cracks on the surface of the metal oxide insulating layer, or a fluid state A method for producing a wiring board, comprising: a step of curing the resin in a state where the resin is pressed into a recess.   8. The manufacturing method of a wiring board according to claim 7, wherein in the case where the recess includes the crack, a crack is formed in the metal oxide insulating layer after the first step and before the second step. Law.   The third step includes a step of arranging a metal foil having a profile on the resin surface or the heat conductive resin insulating layer surface, and the metal foil profile is the resin or the heat conductive resin. 9. The method of manufacturing a wiring board according to claim 7, wherein a process of passing through an insulating layer and contacting the metal oxide insulating layer is performed.

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