JP6921722B2 - Manufacturing method of wiring board - Google Patents

Description

The present invention relates to a method for manufacturing a wiring board having a cavity that opens on at least one surface of a substrate body made of an insulating material and having a pad formed in a recess that opens on the bottom surface of the cavity.

For example, a substrate body in which a plurality of ceramic layers are laminated and has a front surface and a back surface, a conical cavity formed through a part of the ceramic layers on the front surface side of the substrate body, and a bottom surface of the cavity. A wiring for mounting a light emitting element, which includes a pair of pads formed on the upper surface of the ceramic layer on the back surface side, and two via conductors that individually contact the bottom surface of the pads and penetrate the ceramic layer on the back surface side. Substrates have been proposed (see, for example, Patent Document 1).

However, in a cavity formed by punching out a ceramic layer located on the surface side of a substrate body in which a plurality of ceramic layers having a predetermined thickness are individually laminated, such as the wiring board for mounting a light emitting element. Since the depth of the cavity is determined depending on the thickness of the green sheet before firing, which is the ceramic layer, it is difficult to obtain a cavity having a sufficient depth according to the thickness of the electronic component to be mounted later. there were. Therefore, there is no choice but to form a cavity having a depth considerably larger than the thickness of the electronic component, and there is a problem that it is difficult to meet the demands for miniaturization, low profile, and high density.
Further, since the pads are formed by printing on the upper surface of the ceramic layer including the upper end surface of the via conductor through which the ceramic layer on the back surface side which is the bottom surface of the cavity is penetrated, all of them are fired. , The electrical connection between the pad and the via conductor can be unstable. Moreover, since the bottom surface of the cavity is fired with the pads arranged, it is difficult to obtain high flatness by firing different materials at the same time because the bottom surface of the cavity undulates during firing. There was also the problem of becoming.

Japanese Unexamined Patent Publication No. 2006-222358 (pages 1 to 14, FIGS. 1 to 10)

The present invention solves the problems described in the background art, and has a cavity having a depth optimum for the thickness of an electronic component to be mounted on at least one of a pair of opposing surfaces in a substrate body made of an insulating material. Further, the present invention provides a method for manufacturing a wiring board in which the electrical connection between the pad provided on the bottom surface of the cavity and the via conductor in contact with the pad is stable and the bottom surface of the cavity has high flatness. Is an issue.

Means for Solving Problems and Effects of Invention

In order to solve the above problems, the present invention has a via conductor that is previously arranged directly under the cavity when the cavity is formed by grinding and the recess that accommodates the base side of the pad is ground on the bottom surface of the cavity. It was created with the idea of grinding one end of the beer as well.
That is, the method for manufacturing a wiring board according to the present invention (claim 1) is a substrate main body made of an insulating material and having a pair of opposing surfaces, a cavity that opens to at least one surface of the substrate main body, and the cavity. Manufacture of a wiring board comprising at least one recess that opens to the bottom surface and a pad that has at least a base side formed in the recess and is connected to a via conductor formed along the thickness direction in the substrate body. The method is a substrate main body preparation step of preparing a substrate main body made of an insulating material, having a pair of opposing surfaces, and internally providing a via conductor along the thickness direction between the pair of surfaces, and the substrate. The first grinding step of grinding at least one surface of the main body to form a cavity having a relatively high flat bottom surface and a side surface erected from the periphery of the bottom surface, and a part of the bottom surface of the cavity. A second grinding step of grinding one end side of the via conductor to form a recess in which one end side of the via conductor is exposed on the bottom surface, and filling the recess with a conductive paste containing a metal powder to form the recess. It is characterized by including a pad forming step of forming a pad in which at least the base side is located.

According to the method for manufacturing a wiring board, the following effects (1) and (2) can be obtained.
(1) By the first grinding step, at least one surface of the substrate body is ground to form a cavity including a bottom surface having a relatively high flatness, and by the second grinding step, one of the bottom surfaces of the cavity is formed. A recess is provided in the portion, and a pad in which at least the base side is located is formed in the recess by the pad forming step. As a result, the height of the upper surface of the pad can be appropriately selected as described later, and the depth of the cavity can be made an optimum depth without excess or deficiency according to the thickness of the electronic component to be mounted later. .. In addition, when the insulating material is ceramic, the cavity is formed by the first grinding step after firing, so that the flatness of the bottom surface of the obtained cavity is made higher than that formed by firing. be able to.
(2) One end surface of the via conductor whose one end side has been ground is exposed on the bottom surface of the recess provided in a part of the bottom surface of the cavity by the second grinding step at the same time when the bottom surface of the recess is ground. I'm letting you. Therefore, since one end surface of the via conductor is surely exposed to the bottom surface of the recess, the electrical connection between the pad formed in the recess including the one end surface of the via conductor and the via conductor is stabilized. be able to.

The insulating material is ceramic (for example, alumina, aluminum nitride, mullite, glass-ceramic, etc.) or resin (for example, epoxy-based, polyimide-based, etc.).
Further, the substrate body is a multilayer laminate of the ceramic or resin, a single layer of the ceramic or resin, or a composite laminate in which a single-layer or multi-layer ceramic layer and a single-layer or multi-layer resin layer are laminated. Consists of one of the bodies. The monolayer can be produced by, for example, a method of firing or curing an insulating material containing ceramic powder or resin powder, or can be produced by a 3D (three-dimensional) printer using ceramic powder or resin powder. ..
Further, the pair of front surfaces facing each other in the substrate body are relative names, and for example, one may be referred to as a front surface and the other may be referred to as a back surface.

Further, the via conductor includes not only a form incorporated inside the substrate main body but also a form in which one end surface is exposed on at least one surface of the substrate main body.
Further, the substrate main body may further be provided with an inner layer wiring that electrically connects to the via conductor.
Further, the flatness is an index that makes it possible to display the smoothness (uniformity) of the plane numerically, and is based on or conforms to JIS B 0621-1984. For example, when the flatness is ± 10 μm or less, it means that the concave or convex in the thickness direction of the reference virtual plane is 10 μm or less for each side.
Further, a cylindrical grindstone is used for the grinding, and fine carbide abrasive grains such as WC, diamond abrasive grains, alumina abrasive grains and the like are fixed to the surface of the grindstone.
In addition, the surface of the pad that is exposed to the outside may be coated with a metal coating (for example, a nickel coating and a gold coating) for rust prevention by electrolytic metal plating or the like.

The present invention also includes a method for manufacturing a wiring board (claim 2), in which the flatness of the bottom surface of the cavity is ± 10 μm or less.
According to this, since the flatness of the bottom surface of the cavity is ± 10 μm or less, the effect (1) can be further exhibited.

Further, the present invention includes a polishing step of polishing a pair of opposing surfaces in the substrate body to make the pair of surfaces parallel to each other and having a relatively high flatness before the first grinding step. , A method for manufacturing a wiring board (claim 3) is also included.
According to this, before the first grinding step of forming the cavity, the polishing step of polishing a pair of surfaces facing each other on the substrate main body is performed in advance. As a result, since the first grinding step is performed on the basis of each of the polished and relatively smooth surfaces, the depth of the bottom surface of the formed cavity is made uniform with respect to the surface on which the cavity opens. Therefore, the effect (1) can be obtained more reliably.
A roller-shaped grindstone is used in the polishing step, and fine cemented carbide abrasive grains, diamond abrasive grains, alumina abrasive grains, and the like are fixed to the surface of the grindstone.

The present invention also includes a method for manufacturing a wiring board (claim 4), in which the flatness of the pair of surfaces facing each other in the substrate body after the polishing step is ± 30 μm or less.
According to this, the flatness of the pair of surfaces facing each other in the substrate main body is made smooth in advance by ± 30 μm or less by the polishing step, so that the effect (1) can be remarkably exhibited. Become.

Further, in the present invention, the upper surface of the pad is located inside the recess in the thickness direction of the substrate body, is flush with the opening of the recess, or is more than the opening of the recess. Also included is a method of manufacturing a wiring board (claim 5), which is located on the outside and inside the cavity.
According to this, the position of the upper surface (top surface) of the pad is inside the recess, at a height flush with the opening of the recess, or outside the opening of the recess and inside the cavity. It is located in one of. As a result, the electronic component mounted on the bottom surface of the cavity and the pad are electrically and reliably mounted via a bonding wire having an optimum length or a brazing material layer having an optimum thickness. Can be done. Therefore, the effect (1) can be obtained more reliably.
The positions of the upper surfaces of the plurality of pads formed in the same cavity may be different from each other.

The present invention also includes a method for manufacturing a wiring board (claim 6), in which a plurality of the recesses and the pads are formed on the bottom surface of the cavity.
According to this, at least a plurality of pads having the same number as the total number of external electrodes provided on the electronic component to be mounted and recesses are formed in advance for each of the pads, so that the effect (1) can be surely obtained. It becomes possible.
The bottom surface of the cavity includes not only a rectangular (rectangular or square) shape in a plan view, but also a circular shape, an oval shape, an elliptical shape, and a polygonal shape of a pentagon or more.
Further, the recess has a circular shape, a rectangular shape, an oval shape, or the like in a plan view.

In addition, the present invention includes a mounting step of fixing the electronic component to the bottom surface of the cavity and electrically connecting the external electrode of the electronic component and the pad after the pad forming step. , A method for manufacturing a wiring board (claim 7) is also included.
According to this, an electronic device having the effect (1) can be surely obtained.
Examples of the electronic component include a semiconductor element, a light emitting element, and a piezoelectric element.

(A) is a schematic view showing a polishing process of the present invention, and (B) and (C) are a schematic view showing a first grinding process. (A) and (B) are schematic views showing a second grinding process, (C) is a schematic view showing a pad forming process, and (D) is a schematic view showing a mounting process. (A) and (B) are schematic views showing a wiring board in which pads of different forms are formed. The schematic diagram which shows the wiring board of the form different from the said obtained by this invention.

Hereinafter, embodiments for carrying out the present invention will be described.
FIG. 1A is a vertical cross-sectional view showing one form of the substrate body 2 used in the present invention, and a schematic view showing the polishing process of the present invention.
As shown in FIG. 1A, the substrate main body 2 has a pair of surfaces 3a and 4a in which a plurality of ceramic layers (insulating materials) c1 to c3 having an arbitrary thickness are integrally laminated and opposed to each other. ing. A plurality of via conductors 6 are formed at appropriate positions in the ceramic layers c1 to c3 along the respective thickness directions. Further, an inner layer wiring 5 connected to the upper and lower via conductors 6 is formed between the ceramic layers c1 and c2.
The pair of surfaces 3a and 4a are relative names. Therefore, in the following, one is referred to as the front surface 3a and 3 and the other is referred to as the back surface 4a and 4 including after polishing.
Further, the ceramic layers c1 to c3 contain, for example, alumina as a main component, and the inner layer wiring 5 and the via conductor 6 are, for example, mainly tungsten (hereinafter, simply referred to as W) or mainly molybdenum (hereinafter, simply referred to as W). , Simply described as Mo).

In the substrate main body 2, the three layers of green sheets to be the ceramic layers c1 to c3 are punched to form via holes at predetermined positions, and each of the via holes is conductive containing W powder, Mo powder, or the like. The same conductive paste is pattern-printed at appropriate positions on the surface of any of the green sheets, and then the green sheets are laminated and fired to prepare in advance.
First, a polishing step was performed on the front surface 3a and the back surface 4a of the substrate main body 2 to make them a smooth front surface 3 and a back surface (front surface) 4. That is, as shown in FIG. 1A, the roller-shaped grindstone g1 fixed to the rotation axis s in the horizontal posture was moved along the surface 3a of the substrate main body 2 while rotating at high speed. Further, the same polishing work was performed along the back surface 4a of the substrate main body 2. Fine carbide abrasive grains such as WC or diamond abrasive grains are fixed to the circumferential surface (surface) of the grindstone g1.
As a result, as shown in FIG. 1 (B), the front surface 3a and the back surface 4a of the substrate main body 2 have a flatness of ± 30 μm or less (for example, ± 3 μm) and are parallel to each other and face each other. And the back side 4.

Next, as shown in FIG. 1 (B), a first grinding step for forming a cavity (7) opening in the surface 3 is performed on the central side of the surface 3 of the substrate body 2 in a plan view. rice field. That is, while rotating the rotating shaft s in a vertical posture with respect to the flat surface 3 and the cylindrical grindstone g2 fixed to the lower end side thereof, the outer peripheral side draws a rectangular locus in a plan view. I moved it like this. Such grinding work was continuously performed a plurality of times from the surface 3 of the substrate main body 2 along the thickness direction thereof. It should be noted that the same WC carbide abrasive grains and the like are fixed to the circumferential surface and the tip surface of the grindstone g2.
As a result, as shown in FIG. 1 (C), the bottom surface 8 is open to the center side of the surface 3 of the substrate main body 2 in a plan view, and the bottom surface 8 has a rectangular shape in a plan view, and the periphery of the bottom surface 8 is moved to the surface 3 side. A cavity 7 is formed, which is composed of the side surfaces 9 of the four sides that are erected and has a rectangular parallelepiped shape as a whole. The flatness of the bottom surface 8 was ± 10 μm or less (for example, ± 3 μm).
The bottom surface 8 of the cavity 7 was located inside (intermediate) in the thickness direction of the ceramic layer c2 of the middle layer.

Next, as shown in FIG. 2A, a second grinding that forms two (plurality) recesses (10) that open in the bottom surface 8 at appropriate locations on the bottom surface 8 of the cavity 7 in the substrate body 2. The process was performed. That is, in FIG. 2A, the bottom surface of the cavity 7 is located on the right end side of the bottom surface 8 and directly above the upper end (one end) side of the via conductor 6 penetrating the ceramic layer c3 of the lowermost layer. With respect to 8, the rotating shaft s in a vertical posture and the slightly small-diameter cylindrical grindstone g3 fixed to the lower end side thereof are moved so as to draw a circular locus on the outer peripheral side in a plan view while rotating. rice field. An operation of moving the grindstone g3 so as to sequentially approach the back surface 4 side along the axial direction was also added.

Subsequently, in FIG. 2A, the same grinding work as described above was performed on the position on the left end side of the bottom surface 8 of the cavity 7. It should be noted that the same WC carbide abrasive grains and the like are fixed to the circumferential surface and the tip surface of the grindstone g3.
As a result, as shown in FIG. 2 (B), each of the positions on the right end side and the left end side of the bottom surface 8 of the cavity 7 has a circular shape in a plan view, and the bottom surface 11 is the thickness of the ceramic layer c3 which is the lowest layer. Two (plurality) recesses 10 located inside in the direction and having a cylindrical shape as a whole were formed. When the recess 10 is formed in the second grinding step, as shown by the broken line in FIG. 2 (B), the upper end (one end) side of the via conductor 6 formed through the ceramic layer c3. 6e was also ground at the same time. As a result, a new upper end (one end) surface of the via conductor 6 was exposed flush with the bottom surface 11 on the bottom surface 11 of each recess 10.

Further, a pad forming step was performed in which, for example, a conductive paste containing powder of an Au—Sn alloy was filled inside each of the recesses 10 by using a filling means such as a dispenser (not shown).
As a result, as shown in FIG. 2C, the base side occupies the inside of the recess 10 and the bottom surface is connected to the via conductor 6, and the upper surface (top surface) is outside the opening of the recess 10. Two pads 12 located in the cavity 7 (upper side) and having a cylindrical shape as a whole were formed.
Subsequently, after curing the pad 12 by heating it, the substrate main body 2 including the pad 12 is sequentially immersed in an electrolytic nickel plating bath and an electrolytic gold plating bath to externalize each pad 12. A plating step was performed in which a nickel film and a gold film (neither shown) were sequentially coated on the surface exposed to the surface.
As a result, as shown in FIG. 2C, a cavity 7 having a desired depth is opened on the surface 3 side of the substrate main body 2, and each of the two recesses 10 provided on the bottom surface 8 of the cavity 7 is said to be on the bottom surface. It was possible to obtain a wiring board 1 having two pads 12 electrically stably connected to the via conductor 6.

Then, as shown in FIG. 2D, after mounting the electronic component 14 on the center side of the bottom surface 8 of the cavity 7 via a bonding material (not shown) or the like in a plan view, the electronic component 14 has 2 The two external electrodes (not shown) and the upper surfaces of the two pads 12 were individually electrically connected by a bonding wire 15.
As shown in FIG. 3A, even if the upper surface of each pair of left and right pads 12 is formed so as to be substantially flush with the bottom surface 8 of the cavity 7, the pads 12 are mounted in the same manner as described above. The electronic component 14 can be easily electrically connected to the electronic component 14 via the bonding wire 15. Further, even if the upper surface of each pad 12 is located inside each recess 10, the pad 12 and the electronic component 14 can be electrically connected via the bonding wire 15. ..

Further, as shown in FIG. 3B, the two recesses 10 are formed on the slightly center side of the left end and the right end of the bottom surface 8 of the cavity 7, and the upper surface of each recess 10 is the bottom surface 8 of the cavity 7. The wiring board 1 may be in the form of a pad 12 protruding into the cavity 7 on the outer side. An electronic component 14 having an external electrode (not shown) on the peripheral side of the bottom surface can be mounted on the upper surface of each pad 12 via a solder 16 made of an alloy having a relatively low melting point. Therefore, the electronic component 14 can be an electronic device mounted by arranging the electronic component 14 inside the cavity 7 in just proportion.
In the wiring board 1 described above, after the polishing step, a plurality of external connection terminals (not shown) are formed at appropriate positions on the back surface 4 of the substrate main body 2, and the via conductor 6 is formed for each of the external connection terminals. It may be possible to conduct the pad 12 individually via the pad 12. Alternatively, any of the external connection terminals may be made conductive with the via conductor 6 and the inner layer wiring 5 located outside the cavity 7.
Further, the bonding wire 15 may be mounted instead of the above-mentioned bonding wire 15, or the bonding wire 15 may be used instead of the solder 16.

FIG. 4 is a schematic view showing a wiring board 1h having a different form obtained by the present invention.
The wiring board 1h is formed by laminating a plurality of resin layers j1 to j3 and a plurality of ceramic layers c1 and c2, and has a substrate main body 2h having an opposing front surface 3 and a back surface 4 and a surface 3 of the substrate main body 2h. It includes a cavity 7 having a relatively wide plan view that opens to the center side of the plan view, and a pair of left and right cavities 7 that open to the back surface 4 of the substrate main body 2h and have a relatively narrow plan view. The substrate body 2h is formed by bonding resin layers j1 to j3 and ceramic layers c1 and c2, which are individually laminated in advance, between the resin layer j3 and the ceramic layer c1 via an adhesive layer (not shown). be.
The resin layers j1 to j3 are made of, for example, a polyimide (PI) -based resin, and the ceramic layers c1 and c2 are made of the same alumina.

Further, a plurality of inner layer wirings 17 and via (filled via) conductors 18 connecting between the resin layers j1 to j3 and individually penetrating the resin layers j2 and j3 are formed between the resin layers j1 to j3. .. The inner layer wiring 17 and the via conductor 18 are mainly made of copper, and are appropriately formed together with the resin layers j1 to j3 by a photolithography technique.
A plurality of inner layer wirings 5 previously formed on one side of the ceramic layer c1 are located between the resin layer j3 and the ceramic layer c1. The inner layer wiring 5 is made electrically conductive with the pad 12 formed for each recess 10 opened in the bottom surface 8 of the cavity 7 opening in the surface 3 via the via conductor 18. Further, the inner layer wiring 5 is a pad 12 formed for each recess 10 opened in the bottom surface (ceiling surface) 8 of the two cavities 7 opened in the back surface 4 via the via conductor 6 penetrating the ceramic layer c1. Both are individually conductive.

In order to obtain the wiring board 1h as described above, the board body 2h was prepared in advance, and the front surface 3a and the back surface 4a were polished to obtain smooth front surfaces 3 and back surfaces 4.
Next, the same first grinding step is performed on the front surface 3 and the back surface 4 at appropriate locations so that the surface 3 is widely opened to the center side and the bottom surface 8 is in the thickness direction of the middle resin layer j2. A cavity 7 located inside (middle) and two cavities 7 that are narrowly opened to the left and right of the back surface 4 and whose bottom surface (ceiling surface) 8 is located in the middle of the lower ceramic layer c2 in the thickness direction are sequentially arranged. Formed.
Next, the same second grinding step was sequentially performed for each suitable place on the bottom surface 8 of each of the cavities 7, and a pair of left and right recesses 10 were formed for each of the bottom surfaces 8. At this time, the upper surface (one side) side of each via conductor 18 located between the resin layers j2 and j3 and the lower end (one end) side of each via conductor 6 were also ground at the same time.

Further, a pad forming step of filling each of the recesses 10 with the same conductive paste is sequentially performed, and as shown in FIG. 4, the cavity whose upper surface is outside the bottom surface 8 of each cavity 7 is formed. It was possible to obtain a plurality of the pads 12 located within 7. Then, the exposed surface of each pad 12 was subjected to the plating step to sequentially coat the same metal film.
As a result, as shown in FIG. 4, a plurality of cavities 7 having a desired depth to open in the front surface 3 and the back surface 4 of the substrate main body 2h, and a plurality of recesses formed in the bottom surface 8 of each cavity 7. 10, the wiring board 1h having a plurality of pads 12 having at least a base side located in each of the recesses 10 and via conductors 6 and 18 electrically stably connected to the bottom surface of each pad 12 is obtained. I was able to.
The substrate main body 2 of the wiring board 1h may be in a form in which only five layers (plurality of layers) of ceramic layers are laminated, or in a form in which only five layers (plurality of layers) of resin layers are laminated.
Further, the bonding wire 15 may be used instead of the solder 16.

According to the manufacturing method of the wiring boards 1 and 1h described above, at least one surface 3 of the substrate main bodies 2 and 2h is ground by the first grinding step, and the cavity 7 including the bottom surface 8 having a relatively high flatness is formed. By the second grinding step, a recess 10 is formed in a part of the bottom surface 8 of the cavity 7, and by the pad forming step, a pad 12 in which at least the base side is located is formed in each of the recesses 10. There is. As a result, by appropriately selecting the position of the upper surface of the pad 12, the depth of the cavity 7 can be optimally adjusted according to the thickness of the electronic component 14 to be mounted later.
In addition, when the insulating material constituting the substrate main body 2 is ceramic as in the wiring boards 1 and 1h, the cavity 7 is formed by the first grinding step, so that the cavity 7 is formed as compared with the case where the cavity 7 is formed by firing. The flatness of the bottom surface 8 can be increased.
Further, in the bottom surface 11 of the recess 10 provided in a part of the bottom surface 8 of the cavity 7 by the second grinding step, the via conductor 6 and one end side are ground at the same time as the bottom surface 11 of the recess 10 is ground. One end surface of 18 is exposed. Therefore, the electrical connection between the via conductors 6 and 18 and the pad 12 located in the recess 10 can be surely stabilized.
Therefore, according to the manufacturing method of the wiring boards 1, 1h, the effects (1) and (2) can be surely achieved.

The present invention is not limited to each of the forms described above.
For example, the insulating material constituting the substrate main body 2 and 2h may be a high-temperature co-fired ceramic such as mullite or aluminum nitride, a low-temperature co-fired ceramic such as glass-ceramic, or an epoxy-based resin. In the case of the glass-ceramic or the like or an epoxy resin, for example, copper or silver is applied to the via conductors 6 and 18 and the inner layer wirings 5 and 17.
Further, in the substrate main body 2 and 2h, the ceramic powder or the resin powder is directly three-dimensionally produced by a 3D printer, or the ceramic slurry or the resin slurry is arranged in advance in the internal space such as the via conductor 6. After filling in a predetermined mold, the slurry may be cured to produce the slurry.

Further, the front surfaces 3, 3a and the back surfaces 4, 4a of the substrate pieces 2 and 2h may have a rectangular shape in a plan view, or a regular polygon or a deformed polygon of a pentagon or more.
Further, the cavity may have a circular shape, an oval shape, an elliptical shape, a regular polygon of a pentagon or more, or a deformed polygon in a plan view.
Further, the recess may have a rectangular shape, an oval shape, an elliptical shape, a regular polygon of a pentagon or more, or a deformed polygon in a plan view, or one is provided on the bottom surface of one cavity. Or, three or more may be installed side by side.
In addition, the cavity 7 and the recess 10 may be a wiring board formed only on the back surface 4 side of the substrate books 2 and 2h.

According to the present invention, on at least one of a pair of surfaces of a substrate body made of an insulating material, a cavity having a depth optimum for the thickness of the electronic component to be mounted is provided, and a pad and the pad provided on the bottom surface of the cavity are provided. It is possible to reliably provide a method for manufacturing a wiring board in which the electrical connection with the via conductor in contact with the via conductor is stable and the bottom surface of the cavity has a high flatness.

1,1h ... Wiring board 2,2h ... Board body 3a, 3 ... Front side 4a, 4 ... Back side (front side)
6, 18 …… Via conductor 7 ……………… Cavity 8 ……………… Bottom of the cavity 9 ……………… Side of the cavity 10 ………… Recess 11 ………… Bottom of the recess 12 ………… … Pad 14 ………… Electronic components c1 to c3… Ceramic layer (insulating material)
J1 to j3 ... Resin layer (insulating material)

Claims (7)

A substrate body made of an insulating material and having a pair of opposing surfaces, a cavity that opens to at least one surface of the substrate body, at least one recess that opens to the bottom surface of the cavity, and at least a base in the recess. A method for manufacturing a wiring board, comprising: a pad for connecting to a via conductor whose side is formed and formed along the thickness direction in the board body.
A substrate body preparation step of preparing a substrate body made of an insulating material, having a pair of opposing surfaces, and internally providing a via conductor along the thickness direction between the pair of surfaces.
The first grinding step of grinding at least one surface of the substrate body to form a cavity having a bottom surface having a relatively high flatness and a side surface erected from the periphery of the bottom surface.
A second grinding step of grinding a part of the bottom surface of the cavity and one end side of the via conductor to form a recess in which one end side of the via conductor is exposed to the bottom surface.
The recess includes a pad forming step of filling the recess with a conductive paste containing a metal powder to form a pad in which the base side is located at least in the recess.
A method for manufacturing a wiring board, which is characterized in that. The flatness of the bottom surface of the cavity is ± 10 μm or less.
The method for manufacturing a wiring board according to claim 1, wherein the wiring board is manufactured. Prior to the first grinding step, there is a polishing step of polishing a pair of opposing surfaces in the substrate body to make the pair of surfaces parallel to each other.
The method for manufacturing a wiring board according to claim 1 or 2, wherein the wiring board is manufactured. After the polishing step, the flatness of the pair of surfaces facing each other in the substrate body is ± 30 μm or less.
The method for manufacturing a wiring board according to claim 3, wherein the wiring board is manufactured. The upper surface of the pad is located inside the recess in the thickness direction of the substrate body, is flush with the opening of the recess, or is outside the opening of the recess and of the cavity. Located inside,
The method for manufacturing a wiring board according to any one of claims 1 to 4, wherein the wiring board is manufactured. A plurality of the recesses and the pads are formed on the bottom surface of the cavity.
The method for manufacturing a wiring board according to any one of claims 1 to 5, wherein the wiring board is manufactured. After the pad forming step, there is a mounting step of fixing the electronic component to the bottom surface of the cavity and electrically connecting the external electrode of the electronic component and the pad.
The method for manufacturing a wiring board according to any one of claims 1 to 6, wherein the wiring board is manufactured.

Images