JP5235627B2 - Multiple wiring board - Google Patents

Description

  In the present invention, a large number of wiring board regions, each of which is a small wiring board for mounting electronic components such as semiconductor elements and crystal resonators, are arranged in a vertical and horizontal arrangement on a large-area mother board. The present invention relates to a wiring board.

  2. Description of the Related Art Conventionally, for example, a wiring board used for manufacturing an electronic device by mounting an electronic component such as a semiconductor element or a crystal resonator has a plurality of rectangular plate-like ceramic insulating layers made of ceramics such as an aluminum oxide sintered body. It is a structure in which wiring conductors that are stacked in layers and are electrically connected to electronic components are provided on the surface of the stacked body.

  Such a wiring board has become extremely small with a size of several millimeters square with the recent miniaturization of electronic devices. In order to efficiently produce such a small wiring board and electronic device, a so-called multi-cavity wiring board configuration in which a large number of wiring boards are obtained from a single mother board made of a ceramic material or the like. Wiring boards and electronic devices are manufactured.

  An example of a conventional multi-piece wiring board is shown in FIG. FIG. 7A is a cross-sectional view showing an example of a conventional multi-cavity wiring board, and FIG. 7B is an enlarged cross-sectional view of a main part showing an enlarged P2 portion of FIG. c) is an enlarged plan view of the main part of the main part of FIG. In FIG. 7C, in order to make the wiring conductor and the plating connecting conductor described later easier to see, a part of the mother board covering them is shown cut.

  In this multi-piece wiring board, a plurality of wiring board regions 22 are arranged in a vertical and horizontal arrangement on a square plate-like mother board 21 made of an insulating material such as an aluminum oxide sintered body, and each wiring board area 22 (wiring board) A recess 26 for accommodating an electronic component (not shown) is formed on the upper surface. A wiring conductor 23 is formed from the inside of the recess 26 to the lower surface of each wiring board region 22. The wiring conductor 23 is made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, or gold. For example, a metal paste made of a metal fine particle of tungsten or the like and a binder is made by a screen printing method or the like. After printing on a green sheet to be an insulating layer, it is fired at a high temperature to form a conductive metal film.

  Then, an electronic component (not shown) is mounted and fixed on the bottom surface of the recess 26, and the electrode of the electronic component is electrically connected to the wiring conductor 23 in the recess 26 via a conductive connecting material such as a bonding wire or solder. Thereafter, the recesses 26 on the upper surface of the wiring board region 22 are sealed with a material (not shown) such as a lid or a sealing resin, so that a large number of regions serving as electronic devices are produced on the mother board 21. The

  In addition, the wiring conductor 23 formed on the surface such as the bottom surface or the lower surface of the recess 26 of the multi-cavity wiring board prevents the wiring conductor 23 from being oxidatively corroded, and the wiring conductor 23 and each electrode of the electronic component. In order to improve the electrical connectivity to the surface, a plated metal layer made of nickel, gold or the like is applied to the exposed surface by an electrolytic plating method.

  In order to deposit the plated metal layer by this electrolytic plating method, the plating connection conductor 24 for electrically connecting the wiring conductors 23 formed in the adjacent wiring board regions 22 is provided at the boundary of the wiring board region 22. Formed beyond 27. The plating connection conductor 24 can be easily connected to the wiring conductor 23 between the layers of the ceramic insulating layer, and the plating is applied to the plating connection conductor 24 which is not required in the divided wiring board. In order to prevent this from occurring, it is usually formed inside the wiring board region 22 (between the ceramic insulating layers (no symbol) constituting the mother board 21).

  The plating connection conductor 24 is formed, for example, so that a part thereof is exposed to the outer peripheral portion of the mother board 21, and a terminal of a plating jig is connected to the exposed portion, and an external connection is made via the plating terminal. Electrolytic plating is performed by supplying current from the power source to the connecting conductor 24 for plating and the wiring conductor 23. In this case, since the wiring conductors 23 of each wiring board region 22 are sequentially electrically connected via the connecting conductor 24 for plating, by supplying a current to a part of the connecting conductor 24 for plating, A plated metal layer can be applied to the wiring conductor 23 in the substrate region 22 at the same time.

A dividing groove 25 is formed on the main surface (upper surface and lower surface) of the mother board 21 at the boundary 27 of the wiring board region 22, and the mother board 21 is divided in the dividing groove 25. That is, stress is applied so that the mother substrate 21 is bent along the dividing groove 25, and the dividing groove 25 (or the lower surface) facing the tip of the dividing groove 25 on the upper surface side (or the dividing groove 25 on the lower surface side) (or The mother substrate 21 is divided by causing a crack to advance in the thickness direction of the mother substrate 21 and breaking it toward the front end portion of the dividing groove 25) on the upper surface side.
JP 2006-24878

  However, in such a multi-cavity wiring board, when the mother board is divided along the dividing groove, the boundary part of the wiring board region of the plating connection conductor (that is, the part that breaks when the mother board breaks) ), There is a problem that breakage (so-called erosion) occurs at a portion that enters, for example, several tens of μm from the boundary into the inside of the wiring board region. This is because the stress generated when the mother board is bent and split (broken in the thickness direction) acts on the plating connection conductor in the wiring board region, and the plating connection conductor breaks at this portion. by.

  In particular, with the recent miniaturization of wiring boards, particularly the reduction in thickness, the occurrence of the above problems has become remarkable.

  That is, when the wiring board is miniaturized, especially thinned, the ratio of the thickness of the connecting conductor for plating to the thickness of the mother board becomes relatively large. For example, when the number of ceramic insulating layers is the same, a ceramic insulating layer having a thickness of 50 μm per layer is formed rather than forming a connecting conductor for plating having a thickness of 18 μm on a ceramic insulating layer having a thickness of 100 μm per layer. The thickness of the connecting conductor for plating with respect to the thickness of the ceramic insulating layer (mother substrate) is higher when the connecting conductor for plating having a thickness of 18 μm is formed on the substrate. Therefore, the ratio of the stress generated when the mother substrate is divided (broken) to the plating connecting conductor is increased, and the stress tends to occur.

  In addition, when a chipping occurs in the plating connecting conductor, for example, the chipping remains on the exposed side surface of the individual wiring board, so that the reliability as the wiring board (eg, airtight sealing and corrosion resistance) There is a possibility that problems such as deterioration of the appearance and defective appearance may occur.

  The present invention has been devised in view of such conventional problems, and the object thereof is to suppress the occurrence of burrs in the connecting conductor for plating, for example, even when the mother board is thinned. An object of the present invention is to provide a multi-piece wiring board that can be divided.

In the multi-piece wiring board of the present invention, a plurality of wiring board regions are arranged vertically and horizontally, a mother board having a wiring conductor on the surface of the wiring board area, and a main surface of the mother board at the boundary of the wiring board area A multi-cavity wiring board comprising: a dividing groove formed in the wiring board; and a connecting conductor for plating that is formed inside the mother board and connects the wiring conductors across a boundary of the wiring board region, the plating connection conductor, the thickness at the boundary of the wiring substrate area, the wiring rather thin than the thickness of the substrate region, said wiring wider than the width in the width of the boundary is the wiring board in the region of the substrate region Ikoto It is characterized by.

  Further, the multi-cavity wiring board of the present invention, in the above configuration, a plurality of wiring conductors in adjacent wiring board regions are arranged at different positions in the thickness direction of the mother board at the boundary of the wiring board region. It is connected by a connecting conductor for plating.

  In the multi-piece wiring board of the present invention, in each of the above configurations, the main surface of the wiring board region is provided with a recess, and the connection conductor for plating is disposed below the bottom surface of the recess in a side view. It is characterized by being.

  According to the multi-cavity wiring board of the present invention, the connecting conductor for plating is thinner at the boundary of the wiring board region than the thickness within the wiring board region. An increase in the thickness of the plating connection conductor with respect to the thickness of the mother board is suppressed. That is, when the mother substrate is divided (broken) along the dividing groove, the plating connection conductor is broken at the portion formed relatively thin.

  Therefore, when the mother board is divided, the stress acting on the plating connection conductor is suppressed, and the occurrence of breakage in the portion of the plating connection conductor that enters the wiring board area from the boundary of the wiring board area is suppressed. The Therefore, it is possible to provide a multi-piece wiring board that can be divided while suppressing the occurrence of erosion in the connection conductor for plating.

  Further, according to the multi-cavity wiring board of the present invention, the connecting conductor for plating is for plating at the boundary of the wiring board area when the width at the boundary of the wiring board area is wider than the width in the wiring board area. Even if the thickness of the connection conductor is reduced, it is possible to suppress a reduction in the cross-sectional area as a current path for plating of the connection conductor for plating, as the width is increased. Therefore, an increase in resistance to the plating current supplied to the wiring conductor via the plating connection conductor can be suppressed, and a sufficient current can be supplied to the wiring conductor.

  Therefore, it is possible to suppress the occurrence of chipping in the plating connection conductor, and it is possible to provide a multi-piece wiring board in which it is easy to deposit the plating metal layer with a predetermined thickness on the wiring conductor.

  Further, according to the multi-cavity wiring board of the present invention, the wiring conductors in the adjacent wiring board regions are connected to each other by a plurality of plating connection conductors arranged at different positions in the thickness direction of the mother board at the boundary of the wiring board regions. When connected, even if the thickness of the connecting conductor for plating is reduced at the boundary of the wiring board region, the wiring conductors are connected by a plurality of connecting conductors for plating. The reduction of the cross-sectional area as the current path can be suppressed. Therefore, an increase in resistance to the plating current supplied to the wiring conductor via the plating connection conductor can be suppressed, and a sufficient current can be supplied to the wiring conductor.

  Further, according to the multi-cavity wiring board of the present invention, when the concave portion is provided on the main surface of the wiring board region, and the plating connection conductor is disposed below the bottom surface of the concave portion in a side view, By means of the plating connection conductor, it is possible to suppress a decrease in mechanical strength in the portion of the mother board surrounding the recess. For this reason, when the mother board is divided along the dividing groove, the plating connection conductor is squeezed while more effectively preventing mechanical breakage from occurring in the mother board (particularly the portion surrounding the recess). This can be suppressed.

  Next, the multi-piece wiring board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1A is a cross-sectional view showing an example of an embodiment of a multi-piece wiring board according to the present invention, and FIG. 1B is an enlarged cross-sectional view of a main part showing an enlarged P1 portion of FIG. FIG. 1C is a main part enlarged plan view showing a main part when the multi-piece wiring board shown in FIG. In these drawings, 11 is a mother board, 12 is a wiring board area, 13 is a wiring conductor, 14 is a connecting conductor for plating, 15 is a dividing groove for dividing the mother board 11, and 16 is an electronic component (not shown). A recess 17 for mounting and accommodating the wiring board 17 is a boundary of the wiring board region 12. In FIG. 1C, in order to make it easy to see the main parts of the wiring conductor 13 and the connecting conductor 14 for plating, a part of the mother board 11 covering them is shown.

  The mother substrate 11 is formed by laminating a plurality of ceramic insulating layers (not shown) made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, and a glass ceramic. Yes. Further, on the mother board 11, wiring board regions 12 each serving as an individual wiring board (not shown) are arranged vertically and horizontally. In the example shown in FIG. 1, a recess 16 for accommodating an electronic component is formed on the upper surface of the wiring board region 12.

  The concave portion 16 includes a flat plate-like base portion 19 in which a portion that becomes the bottom surface (without a sign) of the concave portion 16 is arranged vertically and horizontally on the top surface, and is laminated on the top surface of the base portion 19, each surrounding the bottom surface of the concave portion 16. A plurality of frame-like portions serving as side wall portions (without reference numerals) are formed by a frame portion 18 that is arranged vertically and horizontally.

  For example, when each ceramic insulating layer is made of an aluminum oxide sintered body, the mother substrate 11 is formed by forming raw material powders such as aluminum oxide, silicon oxide, and calcium oxide into a sheet shape together with an organic solvent, a binder, and the like. After obtaining a plurality of ceramic green sheets (green sheets) and punching them into the recesses 16 at predetermined positions on the green sheets, the green sheets that have been punched are stacked one above the other It is produced by firing. Each of the laminated green sheets becomes a ceramic insulating layer of the mother substrate 11 after firing.

  In addition, the thickness of the ceramic insulating layer which comprises the mother board | substrate 11 obtained by baking a green sheet is about 50-300 micrometers in the case of an aluminum oxide sintered body and glass ceramics, for example.

  On the mother board 11, wiring board regions 12 each serving as an individual wiring board are arranged vertically and horizontally. Further, in the example shown in FIG. 1, a frame-shaped discard margin region (no reference numeral) surrounding the wiring substrate region 12 is provided on the outer peripheral portion of the mother substrate 11. The disposal allowance area is provided, for example, to facilitate handling of a multi-piece wiring board.

  A wiring conductor 13 is formed on the surface (upper surface and lower surface in the example shown in FIG. 1) of each wiring board region 12. The wiring conductor 13 is formed so as to be electrically led out from the inside of the recess 16 which is a part of the upper surface of the wiring board region 12 to the lower surface of the wiring board region 12, and the portion formed inside the recess 16 In addition, the electronic component is electrically connected through a conductive connecting material (not shown) such as a bonding wire or solder.

  In addition, between the portion formed on the upper surface of the wiring board region 12 and the portion formed on the lower surface of the wiring conductor 13, ceramic insulation is used as a part of the wiring conductor 13 in order to electrically connect the two. A through conductor (not shown) or the like penetrating the layer in the thickness direction is disposed.

  The wiring conductor 13 is electrically connected to the electronic component housed in the recess 16 in the individual wiring board, and functions as a conductive path that electrically connects the electronic component to an external electric circuit (not shown). . For example, the electrical connection of the wiring conductor 13 to the external electric circuit is performed by, for example, replacing the portion formed on the lower surface of the wiring board (wiring board region 12) of the wiring conductor 13 electrically connected to the electronic component with the external electric circuit. It is carried out by joining them with solder such as tin-lead solder or tin-silver solder.

  On the exposed surface of the wiring conductor 13, a plated metal layer (not shown) such as nickel, gold, palladium, or copper is used to prevent oxidative corrosion, improve bonding wire bonding properties, solder wettability, and other characteristics. ) Is deposited. The plating metal layer is deposited by electrolytic plating because it is easy to stabilize the characteristics of the plating metal layer and the productivity and economy are good.

  Such a plated metal layer includes, for example, a nickel plating layer having a thickness of about 2 to 12 μm, which is sequentially deposited when the wiring conductor 13 is made of tungsten, molybdenum, manganese, or copper, and a thickness of It is comprised by about 0.5-2 micrometers gold plating layer. In addition to these plating layers, a palladium plating layer, a copper plating layer, or the like may be interposed between the nickel plating layer and the gold plating layer, or a heat treatment may be performed on the nickel plating layer or the like.

  Further, the multi-piece wiring board includes a plating connecting conductor 14 that connects the wiring conductors 13 beyond the boundary 17 of the wiring board region 12. The connecting conductors 14 for plating electrically connect the wiring conductors 13 of the plurality of wiring board regions 12 to each other, and collectively apply the plating metal layer to the wiring conductors 13 of the plurality of wiring board regions 12 by electrolytic plating. It is for making it happen.

  That is, since the wiring conductors 13 are electrically connected to each other between the plurality of wiring board regions 12 via the plating connection conductors 14, for example, a large number of parts of the plating connection conductors 14 are wired. By pulling out to the outer peripheral part (discarding area) etc. of the substrate and supplying current to the drawn part from an external power source through a jig for plating (so-called rack etc.) A current for plating can be supplied to the wiring conductors 13 together.

  The plating connection conductor 14 can be easily connected to the wiring conductor 13 between the layers of the ceramic insulating layer, and the plating is applied to the plating connection conductor 14 which is not required in the divided wiring board. In order to prevent this, etc., it is formed inside the mother board 11 (between the ceramic insulating layers constituting the mother board 11).

  These wiring conductors 13 and plating connection conductors 14 are made of a metal material such as tungsten, molybdenum, copper, or silver. For example, a plurality of through holes are provided at predetermined positions in each wiring board region 12 of the green sheet that becomes the mother board 11 in advance. A hole is formed in advance, and a metal paste such as tungsten is formed by applying or filling the surface of the green sheet and the through hole by screen printing or the like.

  The metal paste is produced by kneading a mixture of metal (for example, tungsten) fine particles and a binder. After this metal paste is printed or applied to a green sheet serving as a ceramic insulating layer, the wiring conductor 13 and the connecting conductor 14 for plating are formed by firing at a high temperature. The metal fine particles have, for example, a spherical shape, a flake shape, a protrusion shape, or an indeterminate shape, and an average particle diameter of about several μm.

  Further, the mother board 11 has dividing grooves 15 formed along the boundaries 17 between the wiring board areas 12 (between the wiring board areas 12 and between the wiring board area 12 and the disposal margin area). By dividing the mother board 11 along the grooves 15, each wiring board region 12 becomes a piece of wiring board.

  In the example shown in FIG. 1, the dividing grooves 15 are formed on the upper and lower surfaces of the mother substrate 11 so as to be at the same position in plan view (facing each other vertically), and in the dividing groove 15 portion of the mother substrate 11. Dividing (breaking) is made easier. Further, the dividing groove 15 has a V-shaped vertical cross-sectional shape in order to effectively concentrate the stress for dividing the mother substrate 11 at the tip thereof and to easily generate a crack. Such a dividing groove 15 is formed by cutting a cutter blade having a V-shaped longitudinal section along the boundary 17 of the wiring board region 12 on the upper surface and the lower surface of the green sheet laminate as the mother substrate 11. Etc. are formed. In this case, the depth of the dividing groove 15 can be adjusted by the cutting depth of the cutter blade. In addition, the angle of the tip (bottom) of the dividing groove 15 can be adjusted by the angle of the tip of the cutter blade (angle formed by both side surfaces of the cutter blade).

  In the multi-cavity wiring board of the present invention, the thickness of the connection conductor 14 for plating at the boundary 17 of the wiring board region 12 is smaller than the thickness within the wiring board region 12. This suppresses the thickness of the plating connection conductor 14 from being increased relative to the thickness of the mother substrate 11 in the dividing groove 15 where the mother substrate 11 is divided. That is, when the mother substrate 11 is divided along the dividing groove 15, the plating connecting conductor 14 is broken at a portion formed relatively thin.

  For this reason, when the mother board 11 is divided (broken), the stress acting on the plating connection conductor 14 is suppressed, and the plating connection conductor 14 enters the wiring board area 12 from the boundary 17 of the wiring board area 12. It is possible to prevent breakage from occurring in the portion. Therefore, it is possible to provide a multi-piece wiring board that can be divided while suppressing the occurrence of erosion in the connection conductor 14 for plating.

  Here, the metal paste used as the connecting conductor 14 for plating may cause aggregation and dispersion failure of the metal fine particles inside, so there is a possibility that a portion with a low sintered density of the metal fine particles may occur when fired at a high temperature. There is. Since the portion where the sintered density of the metal fine particles is low tends to be a starting point of breakage when stress is applied, such a portion enters the wiring substrate region 12 from the boundary 17 of the wiring substrate region 12 in the connecting conductor 14 for plating. When a large stress is applied to the portion where it enters, the connecting conductor 14 for plating tends to be eroded. In contrast, the thickness of the connecting conductor 14 for plating 14 at the boundary 17 of the wiring board region 12 is thinner than the thickness in the wiring board region 12, so that the part where the dividing groove 15 is formed in the connecting conductor 14 for plating It tends to be broken at the boundary 17 of the wiring board region 12. Therefore, it is possible to suppress a large stress from acting on the plating connection conductor 14 in the wiring board region 12, and to prevent the plating connection conductor 14 from being ground due to the stress.

  Note that the thickness of the connecting conductor for plating 14 is not limited to a linear portion corresponding to the boundary 17 of the wiring board region 12 but also has a certain width (for example, the dividing groove 15) from the boundary 17 to the adjacent portion. It is designed to be thin with a width of the opening surface. In this way, even if the part of the mother board 11 that is actually broken is slightly displaced from the boundary 17 of the wiring board area 12 into the wiring board area 12, the connecting conductor 14 for plating is divided when the mother board 11 is divided. It is possible to effectively prevent the occurrence of stagnation.

  In order to make the thickness of the plating connection conductor 14 at the boundary 17 of the wiring board region 12 thinner than the thickness in the wiring board region 12, for example, the wiring conductor 13 and the plating connection conductor 14 in the wiring board region 12 of the green sheet. The metal paste that becomes a part of the above is printed and applied to the position excluding the boundary 17 by a screen printing method or the like, and then the boundary 17 is thinner than the metal paste printed on the wiring board region 12, What is necessary is just to print the metal paste used as the connection conductor 14 for plating.

  As another method, a metal paste to be the plating connection conductor 14 is printed with the same thickness including the boundary 17 of the wiring board region 12, and the metal paste is locally pressed at the boundary 17. Examples thereof include a method of reducing the thickness.

  For example, as shown in FIG. 1, the thickness of the wiring conductor 13 is such that the mother substrate 11 is formed by laminating three ceramic insulating layers made of an aluminum oxide sintered body, and the wiring conductor 13 is made of tungsten or molybdenum. In order to keep the resistance in electrical connection between the electronic component and the external electric circuit low, it is about 15 to 25 μm. In accordance with this, the thickness of the plating connection conductor 14 in the wiring board region 12 is also about 15 to 25 μm.

  On the other hand, the thickness of the connecting conductor 14 for plating 14 at the boundary 17 of the wiring board region 12 may be about 1/3 of the thickness in the wiring board region 12 or slightly thicker. For example, as described above In the case of such a multi-piece wiring board, it may be about 5 to 10 μm. Thus, by making the thickness of the plating connection conductor 14 relatively thin, for example, even when the thickness of the ceramic insulating layer is as thin as about 50 μm, the thickness of the plating connection conductor 14 with respect to the thickness of the mother substrate 11 It is possible to effectively suppress the occurrence of sag in the connecting conductor 14 for plating.

  To give a specific example, the mother substrate 11 is made of five layers of ceramic insulating layers having a thickness of 50 μm made of an aluminum oxide sintered body, and is a square having an outer dimension of about 45 mm × 45 mm when viewed in plan. When the rectangular wiring board regions 12 having outer dimensions of about 2.5 mm × 2 mm are arranged in 15 × 19 vertical and horizontal arrays, tungsten (sintered fine particles) In the case of a multi-piece wiring board in which the thickness of the connecting conductor 14 for plating made of a body is about 18 to 22 μm in the wiring board region 12 and about 6 to 10 μm at the boundary 17 of the wiring board region 12, In the inspection of 28,500 wiring boards, no plating was found on the connecting conductor 14 for plating. It should be noted that a frame-shaped discard margin region surrounding the wiring substrate region 12 was provided on the outer peripheral portion of the mother substrate 11, and a dividing groove 15 was also provided between the discard margin region and the wiring substrate region 12. In addition, the presence or absence of stagnation was visually confirmed by magnifying the exposed portion of the plating connection conductor 14 by 20 times.

  On the other hand, in the conventional multi-cavity wiring board in which the other conditions are the same and the thickness of the connection conductor 14 for plating at the boundary 17 of the wiring board region 12 is about 18 to 22 μm, about 2% piece In the wiring board of No. 1, it was confirmed that the plating connection conductors 14 were overgrown.

  In the example shown in FIG. 1, the plating connection conductor 14 is formed so that the width at the boundary 17 of the wiring board region 12 is wider than the width within the wiring board region 12. Thus, when the connection conductor 14 for plating is formed so that the width at the boundary 17 of the wiring board region 12 is wider than the width within the wiring board region 12, the width of the connection conductor 14 for plating is increased. Accordingly, it is possible to suppress a reduction in the cross-sectional area of the plating connection conductor 14 (the area of the vertical cross section perpendicular to the length direction in which the plating current flows). Therefore, an increase in resistance to the plating current supplied to the wiring conductor 13 via the plating connection conductor 14 can be suppressed. Therefore, in this case, it is possible to suppress the occurrence of chipping in the connection conductor 14 for plating, and it is easier to deposit a plating metal layer with a predetermined thickness on the wiring conductor 13. It can be set as a wiring board.

  When the width of the plating connection conductor 14 at the boundary 17 of the wiring board region 12 is increased, the plating connection conductor 14 is increased in width in accordance with the extent to which the thickness of the plating connection conductor 14 is reduced. Thus, it is preferable that the cross-sectional area of the connecting conductor for plating 14 is substantially constant. For example, regarding the connecting conductor 14 for plating, when the thickness in the wiring board region 12 is a and the width is b, the thickness is 1/3 (1/3 × a) at the boundary 17 of the wiring board region 12 If the width is set to 3 × b, the cross-sectional area is kept constant at a × b. In this case, as in the example shown in FIG. 1, when the thickness of the connecting conductor for plating 14 is gradually decreased from the thick part to the thin part, the width is gradually increased accordingly. You can do it.

  In order to form such a plating connection conductor 14, for example, when printing the metal paste to be the plating connection conductor 14 described above, the width of the pattern in the portion where the thickness is reduced is increased to a predetermined width. Printing may be performed using the printing plate as described.

  In the example of this embodiment, the dividing groove 15 has a total depth of 30 to 70 with respect to the thickness of the mother substrate 11, the dividing groove 15 on the upper surface side of the mother substrate 11 and the dividing groove 15 on the lower surface side. It is formed to be about%. Further, the upper surface side dividing groove 15 and the lower surface side dividing groove 15 are formed at the same position in plan view (overlapping in plan view). Further, the angle at the tip (bottom) of the split groove 15 on the upper surface side is formed to be smaller than the angle at the tip (bottom) of the split groove 15 on the lower surface side. For example, the mother substrate 11 is bent so that the lower surface side is concave, and the mother substrate 11 is divided by causing a crack to progress from the bottom of the dividing groove 15 on the upper surface side toward the bottom of the dividing groove 15 on the lower surface side. This is because the crack progress direction is prevented from deviating from the split groove 15 on the lower surface side. In such a multi-piece wiring board, the position of the connecting conductor 14 for plating in the thickness direction of the mother board 11 is formed so as to be close to the dividing groove 15 on the upper surface side as shown in FIG. It is desirable to do. This is because the crack progresses away from the portion where the thickness of the plating connection conductor 14 is reduced by reducing the distance between the bottom of the split groove 15 on the upper surface side where the crack starts and the connection conductor 14 for plating. This is because it is effective in preventing this.

  In the example shown in FIG. 1, the plating connection conductor 14 has a thickness between a portion where the thickness in the wiring board region 12 is relatively thick and a portion where the thickness at the boundary 17 of the wiring board region 12 is relatively thin. Is gradually changed at a constant rate, but for example, it may be a cross-sectional shape as shown in FIG. 2 where the thickness is abruptly changed (stepwise in a side view). FIG. 2 is an enlarged cross-sectional view of a main part showing another example of the embodiment of the multi-cavity wiring board according to the present invention. In FIG. 2, the same parts as those in FIG.

  As described above, the structure in which the thickness of the plating connection conductor 14 changes stepwise at a point close to the boundary 17 of the wiring board region 12 is, for example, a thickness corresponding to the portion where the thickness is thin, After the metal paste is printed over the entire length of the predetermined pattern, it can be formed by adding the metal paste to only the thick part and printing it, so the printing process is easy and the productivity of multi-cavity wiring boards is increased. Effective above.

  Further, in the multi-cavity wiring board of the present invention, a plurality of plating conductors in which the wiring conductors 13 of the adjacent wiring board regions 12 are arranged at different positions in the thickness direction of the mother board 11 at the boundary 17 of the wiring board region 12 are provided. In the case where they are connected to each other by the connection conductor 14, the following effects can be obtained.

  That is, for example, as shown in FIG. 3, even if the thickness of the connection conductor 14 for plating is reduced at the boundary 17 of the wiring board region 12, the wiring conductors 13 of the adjacent wiring board regions 12 are connected to each other. Therefore, the reduction in the cross-sectional area of the plating connection conductor 14 (the total cross-sectional area of the plurality of plating connection conductors 14) can be suppressed. Therefore, an increase in resistance to the plating current supplied to the wiring conductor 13 through the plating connecting conductor 14 can be suppressed, and a sufficient current can be supplied to the wiring conductor 13. FIG. 3A is an enlarged plan view of a main part showing another example of the embodiment of the multi-piece wiring board according to the present invention, and FIG. 3B is an AA line in FIG. It is a principal part expanded sectional view in FIG. In FIG. 3, the same parts as those in FIG. Also, in FIG. 3A, a part of the mother board 11 is cut as shown in FIG.

  In addition, since the plurality of connecting conductors 14 for plating are arranged at different positions in the thickness direction of the mother board 11, it is effective in suppressing the width occupied by the connecting conductors 14 for plating at the boundary 17 of the wiring board region 12 It is. Therefore, in this case, it is effective for downsizing of the wiring board region 12 (individual piece of wiring board). For example, at the boundary 17 of the wiring board region 12, the space for arranging the plating connection conductors 14 is narrowed by increasing the density of the wiring conductors 13 and reducing the size of the wiring board region 12, as in the example shown in FIG. In addition, when it is difficult to increase the width of the connecting conductor for plating 14, the above configuration is effective. Of course, the plating connecting conductors 14 may be formed to have a wide width as long as they can be formed at the boundary 17 and at different heights in the thickness direction of the mother board 11.

  In order to arrange the plurality of plating connection conductors 14 for connecting the wiring conductors 13 at different positions in the thickness direction of the mother board 11, for example, the through conductor 20 is formed in the ceramic insulating layer constituting the mother board 11. Through this through conductor 20, the plating connection conductor 14 disposed between the layers of a certain ceramic insulating layer is electrically led out between the layers above or below it, and this lead-out portion is connected to another plating connection conductor. 14 may be connected and arranged. That is, the plurality of upper and lower plating connection conductors 14 are electrically connected to each other by the through conductors 20, and the plurality of plating connection conductors 14 electrically connected to each other are connected to the boundary 17 of the wiring board region 12, respectively. The wiring conductors 13 are electrically connected to each other.

  In addition, the plating connection conductors 14 arranged at different positions in the thickness direction of the mother board 11 may be provided so as not to overlap each other in the boundary 17 of the wiring board region 12 in plan view. In this case, it is effective in suppressing such a problem that the thickness of the mother substrate 11 becomes uneven due to the thickness of the connecting conductor 14 for plating and the surface of the mother substrate 11 is uneven.

  Further, for example, as shown in FIG. 4, in the case of separately connecting the connecting conductors 14 for plating to a plurality of wiring conductors 13 that need to be electrically independent from each other in the divided wiring board, A plurality of plating connection conductors 14 that connect the wiring conductors 13 may be arranged between different layers (in a so-called staggered pattern). In this case, the adjacent wiring conductors 13 are more effectively prevented from being short-circuited via the plating connection conductor 14, and the predetermined electrical characteristics can be more reliably obtained as a piece of wiring board. be able to. 4 is an enlarged cross-sectional view of a main part showing a modification of the multi-piece wiring board of the present invention shown in FIG. 4, parts similar to those in FIGS. 1 and 3 are given the same reference numerals.

  Further, in the multi-cavity wiring board of the present invention, as shown in FIG. 5, for example, a concave portion 16 is provided on the main surface of the wiring board region 12, and the plating connection conductor 14 is connected to the bottom surface of the concave portion 16 in a side view. When arranged below, the following effects can be obtained.

  That is, since the connecting conductor 14 for plating is disposed below the bottom surface of the recess 16, the mechanical strength of the frame portion 18 constituting the side wall portion of the recess 16 in the mother substrate 11 is higher than that of the ceramic insulating layer. It is possible to suppress a decrease due to the presence of the connection conductor 14 for plating having a low mechanical strength. Therefore, when dividing the mother board 11 along the dividing groove 15, it is effective to suppress the occurrence of mechanical breakage in the mother board 11, while causing the connecting conductor 14 for plating to be swept away. Can be suppressed. FIG. 5 is an enlarged cross-sectional view of the main part showing another example of the embodiment of the multi-piece wiring board of the present invention. 5, parts similar to those in FIG. 1 are denoted by the same reference numerals.

  That is, the frame 18 of the mother board 11 is narrower than the base 19 and tends to have a low mechanical strength, so that the plating connection conductor 14 is placed inside beyond the boundary 17 of the wiring board region 12. If formed, the rigidity of the frame portion 18 may be reduced, and mechanical breakage of the mother board 11 may easily occur. In particular, when the wiring board region 12 is downsized, the width of the frame portion of the frame portion 18 that forms the recess 16 tends to be narrowed and the mechanical strength tends to decrease, so the above-described problems are likely to occur. there is a possibility. Therefore, particularly in the case of such downsizing, it is preferable to dispose the plating connection conductor 14 below the bottom surface of the recess 16 in a side view.

  In this case, when the dividing groove 15 is formed from the upper surface of the mother board 11 (frame portion 18), the plating connection conductor 14 is disconnected by forming the plating connection conductor 14 in the base portion 19. Therefore, the depth of the dividing groove 15 can be increased to the vicinity of the upper surface of the base 19 (the bottom surface of the recess 16 in the example shown in FIG. 5). Therefore, there is also an effect that the mother substrate 11 can be more easily divided by securing a sufficient depth of the dividing groove 15. When the dividing groove 15 on the upper surface side of the mother board 11 is deepened in this way, the groove 15 on the upper surface side tends to concentrate a larger stress on the bottom, so that the lower surface side of the mother board 11 is concave (the upper surface side is It is desirable to cause the cracks to progress from the bottom of the upper-side dividing groove 15 toward the bottom of the lower-side dividing groove 15.

  As another example of the embodiment of the multi-piece wiring board of the present invention, as shown in FIG. 6, the frame part 18 constituting the mother board 11 is composed of one ceramic insulating layer, and the base part 19 is composed of two layers. A multi-piece wiring board in which four wiring conductors 13 (13a, 13b, 13c, 13d) that are electrically independent from each other are formed in the recess 16 in the case of being formed of an insulating layer will be described. 6 (a) is an enlarged plan view of a main part showing another example of the embodiment of the multi-piece wiring board according to the present invention, and FIG. 6 (b) is a cross-sectional view taken along line AA in FIG. 6 (a). FIG. 6A and 6B, only one of the many wiring board regions 12 arranged on the mother board 11 is shown. In FIG. 6, the same parts as those in FIG.

  In this case, the connecting conductor 14 for plating connected to the two wiring conductors 13a and 13b on one short side of the rectangular wiring board region 12 is an interlayer of the ceramic insulating layer above the base 19 (the base 19 and the frame portion). The plating connection conductor 14 is disposed between the ceramic insulating layers on the lower side of the base 19 and is connected to the other two wiring conductors 13c and 13d on the other short side. Here, since the wiring conductors 13a, 13b, 13c, and 13d are disposed on the bottom surface of the recess 16 (the upper surface of the base 19), in this example, the wiring conductors 13c and 13d are respectively the through conductors 20 and the lower side of the base 19 Are connected to the plating connection conductors 14 disposed between the ceramic insulating layers. Since the wiring conductors 13a, 13b, 13c, and 13d need to be electrically independent from each other when divided into individual wiring boards, the wiring boards adjacent to each other by different connecting conductors 14 for plating. Connected between regions 12.

  In this case, for example, if the base portion 19 is composed of three or more ceramic insulating layers (not shown), and the plating connection conductors 14 are disposed between two or more of them, adjacent wiring board regions 12 are arranged. When the wiring conductors 13 are connected to each other by a plurality of connecting conductors 14 for plating, the plurality of connecting conductors 14 for plating can be disposed below the bottom surface of the recess 16. Also in this case, mechanical breakage at the time of division in the frame portion 18 of the mother board 11 can be effectively suppressed.

  The multi-cavity wiring board manufactured in this way is divided into individual wiring boards, and thereafter, electronic parts such as crystal units and semiconductor elements are accommodated in the recesses 16 of the wiring board. (Not shown) is joined to the upper surface of the wiring board by a joining method such as brazing or welding (seam weld), and the recess 16 is hermetically sealed, so that a large number of electronic devices can be provided for each of the many wiring boards. Produced.

  Further, the electronic components can be accommodated in the recess 16 and hermetically sealed before being divided into individual wiring boards (in the state of a multi-piece wiring board). In this case, a multi-piece electronic device (not shown) in which a large number of electronic devices are formed on the mother substrate 11 is manufactured, and the multi-piece electronic device is divided along the dividing grooves 15. A number of electronic devices are produced.

  In addition, this invention is not limited to the example of the above-mentioned embodiment, A various deformation | transformation is possible. For example, the mother board 11 has been described by taking as an example one having the recess 16 in each wiring board region 12. However, the mother board 11 may be a flat plate having no such recess 16.

(A) is sectional drawing which shows an example of embodiment of the multi-piece wiring board of this invention, (b) is a principal part expanded sectional view of (a), (c) is the principal part of (a). FIG. It is a principal part expanded sectional view which shows the other example of embodiment of the multi-piece wiring board of this invention. (A) is a principal part enlarged plan view which shows the other example of embodiment of the multi-cavity wiring board of this invention, (b) is a principal part expanded sectional view in the AA of (a). . FIG. 4 is an enlarged cross-sectional view of a main part showing a modification of the multi-cavity wiring board shown in FIG. 3. It is a principal part expanded sectional view which shows the other example of embodiment of the multi-piece wiring board of this invention. (A) is a principal part enlarged plan view which shows an example of embodiment of the multi-piece wiring board of this invention, (b) is a principal part expanded sectional view in the AA of (a). (A) is sectional drawing which shows an example of the conventional multi-piece wiring board, (b) is the principal part expanded sectional view of (a), (c) is the principal part enlarged plan view of (a). is there.

Explanation of symbols

11 ... Mother board
12 ... Wiring board area
13 ・ ・ ・ ・ ・ Wiring conductor
14 ・ ・ ・ ・ ・ Connection conductor for plating
15 ... Dividing groove
16 ... concave
17 ・ ・ ・ ・ ・ Boundary of wiring board area
18 ... Frame
19 ・ ・ ・ ・ ・ Base
20 ... Penetration conductor

Claims (3)

A plurality of wiring board regions are arranged vertically and horizontally, a mother board having a wiring conductor on the surface of the wiring board area, a dividing groove formed on a main surface of the mother board at a boundary of the wiring board area, and the mother board A multi-cavity wiring board formed inside a board and provided with a connecting conductor for plating that connects the wiring conductors beyond the boundary of the wiring board region, wherein the connecting conductor for plating is the wiring board multiple patterning wiring board characterized wide Ikoto than the width of the rather thin, the width at the boundary of the wiring substrate area the wiring substrate area than the thickness of the thickness is the wiring substrate region in the boundary region. The wiring conductors in the adjacent wiring board regions are connected by a plurality of connecting conductors for plating arranged at different positions in the thickness direction of the mother board at the boundary of the wiring board regions. 2. The multi-piece wiring board according to 1. A recess is provided on the main surface of the wiring substrate region, the plating connection conductors, either claim 1 or claim 2, characterized in that disposed below the bottom surface of the recess in a side view Multi-cavity wiring board according to the above.

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