JP5515586B2 - Wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wiring board in which a surface layer is laminated on one surface side of a core layer having a through hole, and more particularly to a circuit board that radiates heat through plating of an inner wall of a through hole.

  In general, as this type of wiring substrate, a substrate in which an electrically insulating surface layer is laminated on one side of an electrically insulating core layer is known. Here, the core layer is usually provided with a through hole. The through-hole is formed by providing a hole penetrating in the thickness direction of the core layer, plating the inner wall of the hole, and filling the hole with a filling member.

  Further, in this wiring board, an inner layer conductor electrically connected to the through hole plating is provided between the surface layer and the core layer, and the inner layer conductor and the conductive surface layer conductor provided on the surface layer are provided. The surface layer is electrically connected through a via hole penetrating in the thickness direction.

  Here, in this wiring board, through holes having different hole diameters may coexist. In this case, generally, the plating formed on the inner wall of the through hole has a large plating thickness in the through hole having a large hole diameter. In the case of a through hole with a small hole diameter, the plating thickness was small. This is because plating tends to deposit on the inner wall of the hole when the hole diameter is large.

  On the other hand, conventionally, plating is performed on the inner wall of a through hole having a different hole diameter, and a hole for a small diameter through hole is formed first, and the inner wall is plated for the first time. A method has been proposed in which holes for large-diameter through holes are formed, and the inner walls of both small-diameter and large-diameter through holes are plated for the second time (see Patent Document 1).

JP 2007-88202 A

  By the way, the inventor has been studying a wiring board in which a heating element such as a power element that generates a large amount of heat and a control element or a passive element that generates less heat are mixedly mounted. In this case, the heat generating element is considered to radiate heat through plating of a through hole provided in the core layer.

  In other words, through-holes with different heat dissipation are provided, control elements and passive elements are connected to through-holes with low heat dissipation, and heating elements are connected to through-holes with high heat dissipation to dissipate heat. Thought to do. In that case, it is necessary to thicken the inner wall of the through-hole having a large heat dissipation property.

  However, in recent years, due to the demand for smaller and thinner wiring boards, the core layer also tends to be thinner, and accordingly, the difference in the plating thickness of the inner wall of the through hole due to the difference in the hole diameter as described above. , Almost no longer occur.

  Moreover, although the method of the said patent document 1 changes the structure of plating with the hole diameter of a through hole, it does not consider the difference in the heat dissipation of a through hole.

  The present invention has been made in view of the above problems, and in a wiring board in which a surface layer is laminated on one side of a core layer having a through hole, and heat is radiated through plating of the inner wall of the through hole, The object is to make it possible to easily control the thickness of the plating on the inner wall of the through hole according to the difference in heat dissipation.

The invention according to claim 1 relates to a method of manufacturing a wiring board. As through-holes (30, 31), first through-holes (30) and second through-holes (31) having different heat dissipation properties are provided. In the step of forming the through holes (30, 31), as a hole penetrating in the thickness direction of the core layer (10), the first through hole (30) having a larger heat dissipation property is used. Holes (30a) and holes (31a) for the second through holes (31) having a smaller heat dissipation property are formed, and plating (32, 33) is formed for the first through holes (30). It is simultaneously formed on the inner wall of the hole (30a) and the inner wall of the hole (31a) for the second through hole (31), and then the filling member is formed in the hole (30a) for the first through hole (30). 34) and then the second through hole (31 The inner wall plating (33) in the hole (31a) for use is made thin by etching, and then the filling member (34) is filled in the hole (31a) for the second through hole (31). And

  According to this, the plating (32) is not etched in the first through hole (30) having the larger heat dissipation, and the plating (33) in the second through hole (31) having the smaller heat dissipation is not formed. Etching can reduce the plating thickness. Therefore, according to the present invention, the thickness of the plating (32, 33) on the inner wall of the through hole (30, 31) can be easily controlled according to the difference in heat dissipation of the through hole (30, 31). it can.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a schematic cross-sectional view of a wiring board according to a first embodiment of the present invention. It is process drawing which shows the manufacturing method of the wiring board of 1st Embodiment. It is a schematic sectional drawing of the wiring board which concerns on 2nd Embodiment of this invention. It is process drawing which shows the manufacturing method of the wiring board of 2nd Embodiment. It is a schematic sectional drawing of the wiring board which concerns on other embodiment of this invention. It is a schematic sectional drawing of the wiring board which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a diagram showing a schematic cross-sectional configuration of a wiring board 1 according to the first embodiment of the present invention. The wiring board 1 of the present embodiment is a laminated board in which the surface layers 20 and 21 are provided on both plate surface sides of the core layer 10 having a plate shape, and the through holes 30 and 31 and the inner layer conductor 40 inside the board. .., 42, via hole 50, and surface layer conductors 60 to 62 provided on the surface layers 20 and 21 are electrically connected.

  The core layer 10 is an electrically insulating plate-shaped member, and is a material in which a glass fiber is impregnated with a resin, an epoxy resin, and a resin containing an inorganic filler such as glass or an inorganic oxide. Etc. The core layer 10 may be a single layer or a multilayered assembly.

  The surface layers 20 and 21 are electrically insulating, and the first surface layer 20 attached to one surface (the upper surface in FIG. 1) of the core layer 10 and the other surface (the lower surface in FIG. 1). ) And the second surface layer 21 attached. The material of the surface layers 20 and 21 can be the same as that of the core layer 10. Each surface layer 20 and 21 may be a single layer or a multilayer assembly.

  Here, the core layer 10 is provided with through holes 30 and 31 that penetrate from one surface of the core layer 10 to the other surface, that is, penetrate the core layer 10 in the thickness direction of the core layer 10. Here, the through holes 30 and 31 include a first through hole 30 and a second through hole 31 having different heat dissipation properties.

  The first through hole 30 having a larger heat dissipation property includes a hole penetrating the core layer 10 in the thickness direction, a first plating 32 provided on the inner wall of the hole, and the hole filled with the hole. And a filling member 34 to be filled.

  On the other hand, the second through hole 31 having a smaller heat dissipation property is filled with the hole penetrating the core layer 10 in the thickness direction, the second plating 33 provided on the inner wall of the hole, and the hole. It is comprised by the filling member 34 which fills a hole.

  Here, the holes constituting both the through holes 30 and 31 are formed by punching the core layer 10 such as punching or cutting. The filling member 34 is made of an electrically insulating material such as an epoxy resin, or a conductive material typified by a metal paste such as copper, and is filled by printing or potting.

  In the present embodiment, as shown in FIG. 1, in the first through hole 30 with the larger heat dissipation, the first plating 32 formed on the inner wall of the first through hole 30 has two plating layers 32 a. , 32b are laminated. Here, the two plating layers 32a and 32b are defined as a lower plating layer 32a and an upper plating layer 32b from the inner wall side of the hole.

  The lower plating layer 32a and the upper plating layer 32b are made of Cu plating or the like formed by electroplating or electroless plating similarly to plating of the inner wall of a general through hole. The lower plating layer 32a and the upper plating layer 32b may be different metal plating, but are typically the same metal. For example, the first plating 32 of the present embodiment can be formed by laminating plating layers 32a and 32b made of two layers of Cu plating.

  On the other hand, in the present embodiment, as shown in FIG. 1, the second plating hole 33 formed on the inner wall of the second through hole 31 with the smaller heat dissipation is a single plating layer. It is supposed to be made up of. As will be described later, the second plating 33 is simultaneously formed by the same plating process as the lower plating layer 32a of the first plating 31, and is made of the same material as the lower plating 32a.

  In the present embodiment, the thickness of the first plating 32 of the first through hole 30, that is, the total thickness of the lower plating layer 32 a and the upper plating layer 32 b is the second thickness of the second through hole 31. The thickness of the plating 33 is larger than the thickness of the plating 33. For example, the thickness of the first plating 32 is 40 μm or more, and the thickness of the second plating 33 is 20 μm or less.

  In the present embodiment, the first through hole 30 and the second through hole 31 may have the same or different hole diameters. In the example shown in FIG. 1, the hole diameter of the first through hole 30 is larger than the hole diameter of the second through hole 31.

  Further, as shown in FIG. 1, the inner layer conductors 40, 41, and 42 are provided between the first surface layer 20 and the core layer 10 and between the second surface layer 21 and the core layer 10, respectively. It has been. Of these inner layer conductors 40 to 42, the inner layer conductor 41 provided on the one surface side of the core layer 10 and immediately above the second through hole 31 is configured as a lid plating 41.

  The lid plating 41 is provided so as to cover the second through-hole 31 and so-called a lid. Here, the lid plating 41 is in contact with and electrically connected to the second plating 33 of the second through hole 31.

  The lid plating 41 is formed of the same layer as the second and subsequent plating layers 32b counted from the inner wall side of the first plating 32 in the first through hole 30. That is, the lid plating 41 is composed of a plating layer that is simultaneously formed in the same plating step as the upper plating layer 32b.

  In addition, the inner layer conductors 40 and 42 excluding the lid plating 41 are formed of the same plating layer as the two plating layers 32a and 32b constituting the first plating 32 here. That is, the inner conductors 40 and 42 are formed of a plating layer that is formed simultaneously with the plating layers 32a and 32b in the plating step of sequentially forming the lower plating layer 32a and the upper plating layer 32b.

  The inner layer conductors 40 and 42 excluding the cover plating 41 are electrically connected to the platings 32 and 33 of the through holes 30 and 31, and are drawn from the through holes 30 and 31 on one surface and the other surface of the core layer 10. It is configured as a turned wiring. Of the inner-layer conductors 40 and 42 serving as the wiring, those that are not in contact with the through-holes 30 and 31 in FIG. 1 are routed and connected at portions not shown.

  Further, in FIG. 1, among the inner layer conductors 40, 42 as the wiring provided on the other surface side of the core layer 10, the inner layer conductor 42 positioned between both the through holes 30, 31 is an inter-through hole connecting conductor 42. It is configured as. One end of the inter-through-hole connecting conductor 42 is connected to the first plating 32 of the first through hole 30 and the other end is connected to the second plating 33 of the second through hole 31.

  In this way, the platings 32 and 33 of the through holes 30 and 31 are electrically and thermally connected to each other side of the core layer 10 via the through-hole connecting conductors 42. On the other hand, on one surface side of the core layer 10, the platings 32 and 33 of the through holes 30 and 31 are not electrically and thermally connected.

  Further, in the wiring board 1 of the present embodiment, as electronic components, a heating element such as a power element that generates a large amount of heat, a control element or a passive element that generates a small amount of heat (hereinafter referred to as a non-heat generating element corresponding to the heating element). The electronic components are mounted on the first surface layer 20 on one side of the core layer 10. On the other hand, a cooling member 2 such as an aluminum casing is connected to the second surface layer 21 on the other surface side of the core layer 10 so as to dissipate heat of the wiring board 1 as shown in FIG.

  Conductive surface layer conductors 60, 61, 62 made of Cu plating or the like are provided on the surfaces of the surface layers 20, 21 as in general. Of the surface layer conductors 60 and 61 of the first surface layer 20, the surface layer conductor 60 located near the first through hole 30 is a conductor for mounting a heating element to which a heating element that requires heat dissipation is mounted and connected. The surface layer conductor 61 located near the through hole 31 is a non-heat-generating element mounting conductor to which a non-heat-generating element such as a control element or a passive element that does not substantially require heat dissipation is mounted and connected.

  Here, the first surface layer 20 has a via hole 50 penetrating in the thickness direction of the first surface layer 20 and electrically connecting the surface layer conductors 60 and 61 for mounting each element to the inner layer conductors 40 and 41. Is provided. The via hole 50 is formed by drilling a hole in the first surface layer 20 with a laser and burying a conductor in the hole by copper plating or the like.

  Further, a surface layer conductor 62 made of the same material as that of the first surface layer 20 is provided on the outer surface of the second surface layer 21 on the other surface side of the core layer 10. It is used for thermally connecting and radiating heat.

  Thus, the wiring board 1 of the present embodiment is configured. The electrical and thermal connection paths between the heat generating elements and the non-heat generating elements in the wiring board 1 will be described. The surface layer conductor 60 for mounting the heat generating elements includes the via hole 50 and the inner layer conductor 40 on one surface side of the core layer 10. To the first plating 32 of the first through-hole 30, and from there, the second through-hole connection conductor 42 on the other surface side of the core layer 10 through the second through-hole connection conductor 42. It is connected to the plating 33, and is connected again to the surface layer conductor 61 for mounting the non-heat-generating element via the lid plating 41, the inner layer wiring 40, and the via hole 50 on the one surface side of the core layer 10.

  Therefore, in the mounted state of the element, the current and heat from the heat generating element flow to the non-heat generating element through this connection path, but the heat from the heat generating element is the second heat dissipation. This through-hole 31 is difficult to pass through, and heat is mainly dissipated to a connecting portion other than the second through-hole 31. Therefore, it is possible to prevent the heat of the heating element from being transmitted to the non-heating element as much as possible.

  Next, a method for manufacturing the wiring board 1 of the present embodiment will be described with reference to FIG. FIG. 2 is a process diagram showing the present manufacturing method, and shows each workpiece in cross-section.

  First, the prepared core layer 10 is obtained by attaching a copper foil to both plate surfaces of a plate-like resin. That is, both plate surfaces of the core layer 10 are made of copper foil. In addition, this copper foil is abbreviate | omitted in FIG. 1, FIG.

  Next, as shown in FIG. 2A, holes 30a and 31a penetrating in the thickness direction of the core layer 10 are provided in the core layer 10 by punching or drilling. As the holes, a first through-hole hole 30a having a larger heat dissipation property and a second through-hole hole 31a having a smaller heat dissipation property are formed.

  Next, the first plating step is performed. Specifically, copper plating is performed by electroless plating or electroplating, and the first plating layer M1 is formed on both plate surfaces of the core layer 10 and the inner walls of the holes 30a and 31a. Of the plating layer M1, the inner wall of the first through-hole hole 30a becomes the lower plating layer 32a, and the inner wall of the second through-hole hole 31a becomes the second plating 33. The state up to this point is shown in FIG.

  Next, as shown in FIG. 2B, the filling member 34 is filled only in the second through hole 31a among the through holes 30a, 31a. Specifically, the first through-hole hole 30a is closed, and the second through-hole hole 31a is opened using a mask K1, and the mask K1 masks one surface of the core layer 10, The filling member 34 is printed and supplied.

  As the filling member 34 is filled, the second through hole 31 is substantially formed. Thereafter, the both plate surfaces of the core layer 10 are used as necessary for the purpose of removing the filling member 34 protruding from the second through-hole 31a and flattening both the plate surfaces of the core layer 10. You may make it grind | polish.

  Then, as shown in FIG. 2C, a second plating step is performed. In this step, specifically, copper plating is performed by electroless plating or electroplating, and the upper surface of the first plating layer M1 on the both plate surfaces of the core layer 10 and the inner wall of the hole 30a for the first through hole 30 is formed. Then, the second plating layer M2 is formed.

  At this time, in the second through hole 31a, the plating layer M1 on the inner wall, that is, the second plating 33 is covered and protected by the filling member 34 buried in the hole 31a, so the second plating layer M2 Does not adhere.

  Of the two plated layers M1 and M2 thus laminated, the inner wall of the first through-hole hole 30a is the first plating 32 composed of the lower plating layer 32a and the upper plating layer 32b. . Further, the through-hole connecting conductor 42 is between the through holes 30a and 31a. Further, the second plating layer M <b> 2 formed immediately above the second through hole 31 becomes the lid plating 41. The state up to this point is shown in FIG.

  Next, as shown in FIG. 2D, the filling member 34 is filled only in the first through-hole 30a out of the through-holes 30a and 31a. Specifically, a method for selectively printing and supplying the filling member 34 using the mask may be used. As the filling member 34 is filled, the first through hole 30 is substantially formed.

  Thereafter, the two plated layers M1 and M2 are patterned into the shape of the inner layer conductors 40 and 42 on both sides of the core layer 10 by photolithography. Thus, the core layer 10 in which both the through holes 30 and 31 and the inner layer conductors 40 to 42 are formed is completed.

  Then, the surface layers 20 and 21 are attached to both surfaces of the core layer 10 by thermocompression bonding and fixed. And the hole used as the via hole 50 with respect to the surface layer 20 is opened with a laser. Next, copper plating is performed by electroless plating or electroplating, and via holes are filled by this copper plating and conductor layers to be the surface layer conductors 60 to 62 are formed.

  And the surface layer conductors 60-62 are formed by patterning the conductor layer used as the surface layer conductors 60-62 by the photolithographic method. Thus, the wiring board 1 of this embodiment is completed.

  By the way, according to the present embodiment, the first plating 32 of the first through hole 30 having the greater heat dissipation is formed by laminating two or more plating layers, so that the heat dissipation having the smaller heat dissipation is achieved. The plating thickness is made thicker than the second plating 33 of only one layer in the second through hole 31 to increase the heat dissipation.

  Therefore, according to the present embodiment, the thicknesses of the platings 32 and 33 on the inner walls of the through holes 30 and 31 having different heat dissipation characteristics can be easily controlled according to the difference in the heat dissipation characteristics. In other words, the thickness of the first plating 32 that is desired to be thickened is such that two or more plating layers are laminated, so that the plating thickness can be controlled in accordance with the heat dissipation regardless of the hole diameter of the through hole. It is.

  In addition, as described above, the first through hole 30 and the second through hole 31 may have the same or different hole diameters. When the holes 30a and 31a for holes are opened, a punching die or a drill having the same diameter may be used for the first through-hole 30a and the second through-hole 31a. And since a drilling jig of the same size can be used in this way, drilling is facilitated.

  In addition, as described above, in the present embodiment, the lid plating 41 that covers the second through hole 31 as an inner layer conductor is provided between the first surface layer 20 and the core layer 10.

  As described above, in the formation of the wiring substrate 1, the first surface layer 20 is attached to one surface of the core layer 10 in which the through holes 30 and 31 are formed, and then the holes that become the via holes 50 by laser in the surface layer 20. Open. Further, this laser drilling is generally performed in this type of wiring board.

  Here, according to the present embodiment, the lid plating 41 is used as the end point stopper in the drilling of the via hole 50 by performing the lid plating 41 on the second through hole 31. Therefore, the second through hole 31 is prevented from being damaged by the laser when the hole is drilled.

  Further, in the present embodiment, the lid plating 41 is made of the same layer as the upper plating layer 32b which is the second plating layer of the first through hole 30, and when the upper plating layer 32b is formed, At the same time, the lid plating 41 is also formed. Therefore, it is not necessary to prepare a separate process for forming the lid plating 41, and the process can be simplified.

  Further, in the present embodiment, as described above, among the electronic components mounted on the one surface side of the core layer 10, the heat generating element that generates a large amount of heat is connected to the first plating 32 of the first through hole 30 to generate heat. The small non-heat generating element is connected to the second plating 33 of the second through hole 31. Between these two elements, both the platings 32 and 33 of the first through hole 30 and the second through hole 31 are electrically and thermally connected in series via the through-hole connecting conductor 42. It is said.

  Therefore, it is possible to prevent the heat from the heat generating element that generates a large amount of heat from being transmitted to the non-heat generating element that generates a small amount of heat by the second through-hole 31 that has a low heat dissipation and is difficult to transmit heat.

  In the illustrated example, the first plating 32 of the first through hole 30 has two layers, but in the present embodiment, the first plating 32 includes three or more plating layers. It may be.

(Second Embodiment)
FIG. 3 is a diagram showing a schematic cross-sectional configuration of the wiring board 3 according to the second embodiment of the present invention. In this embodiment, the difference from the first embodiment will be mainly described.

  As shown in FIG. 3, the wiring board 3 is laminated on the core layer 10, the first surface layer 20 laminated on the one surface side of the core layer 10, and the other surface side of the core layer 10 as described above. The second surface layer 21, the first through hole 30 provided in the core layer 10, the second through hole 31, and the inner layer conductors 40 and 42 provided between the surface layers 20 and 21 and the core layer 10. And surface layer conductors 60, 61 provided in the first surface layer 20, and via holes 50 provided in the first surface layer 20.

  Here, as shown in FIG. 3, in the present wiring substrate 3, the first plating 32 in the first through hole 30 with the larger heat dissipation and the second through hole with the smaller heat dissipation. The second plating 33 in 31 is composed of only one layer, and the thickness of the first plating 32 is larger than the thickness of the second plating 33. This is different from the embodiment.

  That is, regarding the number of platings, this embodiment has a configuration in which the second plating layer 32b of the first plating 32 in the first embodiment is eliminated. In FIG. 3, the hole diameter of the first through hole 30 is larger than the hole diameter of the second through hole 31, but also in the present embodiment, the first through hole 30 and the second through hole 30 are the same. The through holes 31 may have the same or different hole diameters.

  Further, by reducing the number of platings, the cover substrate 41 of the first embodiment is eliminated in the present wiring board 3, and the through-hole connecting conductor 42 and the other inner layer conductors 40 are plated in two layers. The layers are not laminated, but are composed of one plating layer.

  Here, in this embodiment, since the lid plating is omitted, no via hole is provided immediately above the second through hole 31. Instead, the inner layer conductor 40 is routed to a position away from the second through hole 31, and a via hole 50 is provided in the first surface layer 21 at the position, via which the surface layer conductor on the first surface layer 20 is provided. 61 and the second through hole 31 are connected. In FIG. 3, the surface conductor 62 (see FIG. 1) that is thermally connected to the cooling member 2 in the second surface layer 21 on the other surface side of the core layer 10 is omitted.

  Next, the manufacturing method of the wiring board 3 of this embodiment is described with reference to FIG. FIG. 4 is a process diagram showing the present manufacturing method, and shows each workpiece in cross-section.

  First, as in the first embodiment, a core layer 10 is prepared, and a hole 30a for the first through hole having a larger heat dissipation property than the core layer 10 by punching or drilling, and the like. A hole 31a for the second through-hole having a smaller heat dissipation property is formed.

  Then, the first plating step is performed as shown in FIG. Specifically, copper plating is performed by electroless plating or electroplating, and a plating layer M1 is simultaneously formed on both plate surfaces of the core layer 10 and the inner walls of the holes 30a and 31a. Of the plated layer M1, the inner wall of the first through-hole hole 30a is the first plating 32, and the inner wall of the second through-hole hole 31a is the second plating 33. Become.

  Next, as shown in FIG. 4B, the filling member 34 is filled only in the first through-hole 30a of the through-holes 30a and 31a. Specifically, this filling is performed by a selective printing method using the mask K2 as in the first embodiment (see FIG. 2B).

  That is, as shown in FIG. 4A, the second through-hole 31a is closed, and the second through-hole 31a uses a mask K2 that is opened. The filling member 34 is printed / supplied in a state where one surface is masked. As the filling member 34 is filled, the first through hole 31 is substantially formed as shown in FIG.

  The selective filling of the filling member 34 in the present embodiment and the selective filling of the filling member 34 in the first embodiment may be performed by printing with masks K1 and K2 as shown in FIGS. However, the dispensing method may be used.

  Thus, the first plating 32 on the inner wall of the first through hole 30a is sealed and protected by the filling member 34 filling the hole 30a. Then, in this state, the inner wall plating in the second through hole 31a, that is, the second plating 33 is etched to reduce the thickness. The state after this etching is shown in FIG.

  Specifically, this etching is performed by wet etching using a general copper etching solution, for example, an acid-based etchant. At this time, since the plating layers M1 on both plate surfaces of the core layer 10 are also etched, the plating layers M1 on both plate surfaces of the core layer 10 are not etched after the etching. It tends to be thinner than the plating 32.

  That is, in the present embodiment, in the finished wiring board 3, the plating thickness of the first plating 32 of the first through hole 30 tends to be larger than the plating thickness of the inner layer conductors 40 and 42. .

  Next, as shown in FIG. 4D, when the filling member 34 is filled in the second through-hole 31a, the second through-hole 31 is substantially formed. About this filling, it can perform by the printing by a mask, the dispensing method, etc. like the above. When this filling is performed by mask printing, both the plate surfaces of the core layer 10 are polished after the etching and before the filling, and the first through-holes 30 protruding from the plate surface. The filling member 34 may be removed.

  Further, the polishing of both the plate surfaces of the core layer 10 may be performed after the filling member 34 is filled in the second through hole 31a. Thereby, the filling member 34 protruding from the holes 30a, 31a for both through holes is removed, and both plate surfaces of the core layer 10 are flattened. In addition, what is necessary is just to perform these grinding | polishing as needed. The state up to this point is shown in FIG.

  Thus, the through holes 30 and 31 of the present embodiment are formed in the core layer 10. Thereafter, the plating layer M1 is patterned into the shape of the inner layer conductors 40 and 42 on both sides of the core layer 10 by photolithography. Thus, the core layer 10 in which both the through holes 30 and 31 and the inner layer conductors 40 to 42 are formed is completed.

  After that, as in the first embodiment, the surface layers 20 and 21 are attached and fixed to both surfaces of the core layer 10, the holes to be the via holes 50 are formed, the holes for the via holes are filled, and the surface conductor 60 is formed. Conductor layers to be -62 are formed. And the conductor layer used as the surface layer conductors 60-62 is patterned, and the surface layer conductors 60-62 are formed. Thus, the wiring board 3 of this embodiment is completed.

  By the way, according to the manufacturing method of the present embodiment, the first plating 32 in the first through hole 30 with the larger heat dissipation is not etched, and the second in the second through hole 31 with the smaller heat dissipation. Only the plating 33 is etched to reduce the plating thickness.

  Therefore, for example, even if the hole diameters of the first and second through holes 30 and 31 are the same, or the hole diameter of the second through hole 31 is larger than that of the first through hole 30. By thinning by the etching, the plating 33 of the second through hole 31 having the smaller heat dissipation can be made thinner.

  That is, also in the present embodiment, the plating thickness can be controlled in accordance with the heat dissipation property, regardless of the diameter of the through hole, as in the first embodiment. Therefore, according to the present embodiment, the thicknesses of the platings 32 and 33 on the inner walls of the through holes 30 and 31 can be easily controlled according to the difference in heat dissipation of the through holes 30 and 31.

  In the illustrated example, the platings 32 and 33 of the through holes 30 and 31 are one layer, but both may be two or more layers. That is, two or more plating layers M1 may be formed on the inner walls of the holes 30a and 31a for both through holes in FIG.

  At this time, the number of plating layers stacked on the inner walls of both holes 30a and 31a is the same. In this case, the first etching is performed only on the plating 33 of the second through-hole 31 in the subsequent step, so What is necessary is just to make the plating 33 of the second through hole 31 thinner than the plating 32 of the through hole 30.

(Other embodiments)
5 and 6 are schematic cross-sectional views of a wiring board according to another embodiment of the present invention. FIG. 5 shows a partial modification of the wiring board shown in the first embodiment.

  5 is a cover plating that covers the first through-hole 30 as an inner layer conductor provided between the core layer 10 and the first surface layer 20 in the wiring substrate 1 shown in FIG. 43 is added.

  The lid plating 43 is also made of copper plating or the like, like the other inner layer conductors. That is, in this embodiment, in the manufacturing process shown in FIG. 2 of the first embodiment, the third plating process is further performed from the state of FIG. A plating layer may be formed on both plate surfaces of the layer 10.

  Thereafter, as in the first embodiment, the surface layers 20 and 21 are attached and fixed to both surfaces of the core layer 10, the holes to be the via holes 50 are formed, the holes for the via holes are filled, and the surface conductor 60 is formed. By forming and patterning the conductor layer to be -62, the wiring board shown in FIG. 5 is completed.

  In this case, since the same layer as the plating layer forming the lid plating 43 of the first through hole 30 is added, the lid plating 41 of the second through hole 31 has two layers as shown in FIG. The inner layer conductors 40, 42 including the other through-hole connecting conductors 42 are formed by laminating three plating layers.

  In this case, not only the second through-hole 31 but also the first through-hole 30 is provided with a cover plating 43 as an inner layer conductor, and this serves as an end point stopper when laser drilling a via hole. Therefore, a via hole 50 is provided in the first surface layer 20 even immediately above the lid plating 43 of the first through hole 30.

  Then, as shown in FIG. 5, the first plating of the surface layer conductor 60 for the heating element and the first through hole 30 located on the outer surface of the first surface layer 20 through the via hole 50 and the cover plating 43. 32 is connected.

  FIG. 6 shows a partial modification of the wiring board shown in the second embodiment. This is a cover plating 43 for covering the first through-hole 30 as an inner layer conductor provided between the core layer 10 and the first surface layer 20 in the wiring board 3 shown in FIG. A lid plating 41 covering the second through hole 31 is added.

  These lid platings 41 and 43 are made of copper plating or the like, similarly to other inner layer conductors in the wiring board of FIG. That is, in this embodiment, in the manufacturing process shown in FIG. 4 of the second embodiment, a plating process is further performed from the state of FIG. 4E to form plated layers on both plate surfaces of the core layer 10. Just do it. Thereafter, as in the second embodiment, the wiring layers shown in FIG. 6 are completed by pasting and fixing the surface layers 20 and 21 and forming the via holes 50 and the surface layer conductors 60 to 62.

  In this case, since the same layer as the plating layer for forming both lid platings 41 and 43 is added to the wiring board 3 shown in FIG. 3, the connection between the through holes is made as shown in FIG. The inner layer conductors 40 and 42 including the conductor 42 are obtained by laminating two plating layers.

  In this case, since the cover platings 41 and 43 are provided in the through holes 30 and 31, the via holes 50 are provided in the first surface layer 20 immediately above the cover platings 41 and 43 of the through holes 30 and 31. The surface layer conductors 60 and 61 are connected to the platings 32 and 33 of the through holes 30 and 31 through the via holes 50 and the lid platings 41 and 43, respectively.

  In each of the above-described embodiments, the surface layers 20 and 21 are provided on both plate surfaces of the core layer 10. Only the first surface layer 20 may be used. That is, if possible, for example, in the wiring boards 1 and 3 shown in FIGS. 1 and 3, the second surface layer 21 and the surface conductor 62 on the outer surface of the second surface layer 21 may be omitted. Good.

DESCRIPTION OF SYMBOLS 10 Core layer 20 1st surface layer 30 1st through-hole 30a Hole for 1st through-hole 31 2nd through-hole 31a Hole for 2nd through-hole 32 1st plating 32b Upper side of 1st plating Plating layer 33 Second plating 34 Filling member 40 Inner layer conductor 41 Cover plating as inner layer conductor 42 Through-hole connecting conductor as inner layer conductor 60 Surface layer conductor for heating element 61 Surface layer conductor for non-heating element

Claims (1)

A hole penetrating in the thickness direction of the core layer (10) is provided in the electrically insulating core layer (10), plating (32, 33) is provided on the inner wall of the hole, and a filling member (34 is provided in the hole) Through-holes (30, 31) filled with
  Forming an inner layer conductor (40) electrically connected to the plating (32, 33) on one surface side of the core layer (10);
  Subsequently, an electrically insulating surface layer (20) is laminated on one surface side of the core layer (10), and conductive surface layer conductors (60, 61) are provided on the surface layer (20), and the surface layer (20 In the method of manufacturing a wiring board, a via hole (50) is formed which penetrates in the thickness direction and electrically connects the surface layer conductors (60, 61) and the inner layer conductor (40).
  As the through holes (30, 31), a first through hole (30) and a second through hole (31) having different heat dissipation are formed,
  In the formation process of the through holes (30, 31),
As the hole penetrating in the thickness direction of the core layer (10), the hole (30a) for the first through hole (30) having the larger heat dissipation and the second hole having the smaller heat dissipation. Forming a hole (31a) for the through hole (31);
  The plating (32, 33) is simultaneously formed on the inner wall of the hole (30a) for the first through hole (30) and the inner wall of the hole (31a) for the second through hole (31). ,
  Thereafter, the filling member (34) is filled into the hole (30a) for the first through hole (30),
  Next, the inner wall plating (33) in the hole (31a) for the second through hole (31) is etched to form a thin film,
  Thereafter, the filling member (34) is filled in the hole (31a) for the second through hole (31).

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