JP2012146941A - Multi-piece wiring board and wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-piece wiring board and individual wiring boards, in which infiltration of water content from a plating lead wire that is exposed at the time of division is suppressed.SOLUTION: A multi-piece wiring board 9 includes a mother board 1 in which a plurality of insulating layers 1a are stacked and wiring board regions 2 are arrayed vertically and horizontally, a wiring conductor 3 formed from between the insulating layers 1a across to the surface of the wiring board region 2, and a plating connection conductor 4 formed between the insulating layers 1a, for connecting the wiring conductors 3 together across a border 2a of the wiring board region 2. The wiring conductor 3 is made from copper and at least one of molybdenum and tungsten. The plating connection conductor 4 is made from at least molybdenum and tungsten at the border 2a of the wiring board region 2 and at the portion adjoining the border 2a. Since a portion of the plating connection conductor 4 that is exposed at the time of division contains relatively dense molybdenum and tungsten, infiltration of water content from the exposed portion is suppressed.

Description

  In the present invention, vertical and horizontal wiring substrate regions are arranged on a mother substrate in which a plurality of insulating layers made of an aluminum oxide sintered body are laminated, and at least one of molybdenum and tungsten formed in the wiring substrate region The present invention relates to a multi-piece wiring board and individual wiring boards in which wiring conductors made of copper and copper are connected to each other through a plating connecting conductor formed between layers of an insulating layer.

  As a wiring board used for mounting electronic components such as semiconductor elements and surface acoustic wave elements, an insulating board in which a plurality of insulating layers made of an aluminum oxide sintered body are laminated, and an insulating board from the interlayer of the insulating layers And a wiring conductor made of a metallized layer of tungsten or molybdenum formed over the surface of the metal, and the exposed surface of the wiring conductor is covered with a plating layer such as nickel or gold. Such a wiring board is generally manufactured in the form of a multi-piece wiring board in which regions to be a wiring board are arranged vertically and horizontally on a mother board.

  In general, the plating layer is deposited on the exposed surface of the wiring conductor in the state of a multi-piece wiring board in consideration of productivity and cost. That is, connecting conductors for plating that connect the wiring conductors of a plurality of wiring board regions are formed between the insulating layers, beyond the boundaries of the wiring board regions, and the wiring of each wiring board region is connected via the connecting conductors for plating. The conductors are electrically connected. If a plating current is supplied to a part of the plating connection conductor via a plating jig or the like in an electrolytic plating solution such as nickel, the wiring conductor in each wiring board region is connected to the plating connection conductor. The current is sequentially supplied to the exposed surface of the wiring conductor so that the plating layer can be deposited.

  For manufacturing multi-layer wiring boards, metal paste such as tungsten is printed on the pattern of wiring conductors and plating connection conductors on ceramic green sheets formed by adding organic solvent and binder to aluminum oxide powder and glass powder. And firing. During the firing, the glassy material of the ceramic green sheet enters between the metal particles of the metal paste and sinters.

  Then, a multi-piece wiring board in which a plating layer is deposited on the exposed surface of the wiring conductor, for example, along dicing processing or division grooves previously formed on the surface of the mother board along the boundary of the wiring board region. If the process of breaking is performed, the multi-cavity wiring board is divided into individual wiring boards.

  In recent years, in order to keep the electrical resistance of a wiring conductor low, it has been proposed and put into practical use that a wiring conductor is formed of a conductive material in which at least one particle of tungsten and molybdenum is dispersed in copper (matrix). Yes. In this case, the aluminum oxide sintered body containing manganese oxide or the like is used, and the firing temperature is lowered to about 1300 ° C., so that a wiring conductor containing copper can be formed by simultaneous firing with the mother substrate. Similarly to the wiring conductor, the plating connection conductor is also formed of a conductor material in which at least one particle of tungsten and molybdenum is dispersed in copper.

JP 2009-4515 A JP 2009-4516 Gazette

  However, the multi-cavity wiring board and the wiring board according to the prior art have the following problems.

  That is, when the multi-piece wiring board is divided at the boundary of the wiring board region, the end portions of the connection conductors for plating cut on the side surfaces of the individual wiring boards are exposed. Further, this connecting conductor for plating is made of a conductor material in which at least one of tungsten and molybdenum particles is dispersed in copper, and copper particles having a low melting point are bonded to each other before the glassy diffusion starts during firing. For this reason, since the vitreous material of the ceramic green sheet is difficult to enter, voids are likely to be formed inside, and a so-called porous state is likely to occur. Therefore, when the multi-piece wiring board is divided into pieces, the moisture of the outside air easily penetrates between the insulating layer layers from the end portions of the plating connection conductors exposed on the side surfaces of the piece of wiring board. In addition, due to the penetrated moisture, there is a problem that defects such as corrosion and migration occur in the wiring conductor and the connecting conductor for plating between the insulating layers.

  In particular, in recent years, the distance between the wiring conductor and the lead wire for plating in the mother board has become shorter in accordance with the miniaturization of the wiring board, and the above-described problems may occur even with slight water penetration. It is high.

  The present invention has been completed in view of such conventional problems, and an object of the present invention is to provide at least tungsten and molybdenum on a mother substrate in which a plurality of insulating layers made of an aluminum oxide sintered body are laminated. For plating substrates that are exposed when divided into individual pieces in a multi-piece wiring board in which wiring conductors made of copper and copper are formed, and wiring conductors in adjacent wiring board regions are connected to each other via connecting conductors for plating It is possible to effectively suppress moisture permeation from the lead-out line between the insulation layers, and it is easy to manufacture a highly reliable wiring board in which corrosion and migration of the wiring conductor are effectively suppressed. It is an object to provide a multi-piece wiring board and a highly reliable wiring board.

  The multi-cavity wiring board of the present invention comprises a mother board in which a plurality of insulating layers made of an aluminum oxide sintered body are laminated, and a plurality of wiring board regions arranged vertically and horizontally, and an interlayer between the insulating layers. A plurality of wiring conductors formed from the surface of the wiring board region to the surface of the wiring board region, and a plating connection conductor formed between the insulating layers and connecting the wiring conductors across the boundary of the wiring substrate region The wiring conductor is made of at least one of molybdenum and tungsten and copper, and the connecting conductor for plating is made of molybdenum or tungsten at a boundary of the wiring board region and a portion adjacent to the boundary. It is characterized by.

  Further, in the multi-piece wiring board of the present invention, in the above configuration, at least one of nickel, cobalt, and iron is added to a portion made of at least one of the molybdenum and tungsten in the connection conductor for plating. It is characterized by.

The wiring board according to the present invention includes an insulating substrate formed by laminating a plurality of insulating layers made of an aluminum oxide sintered body, a wiring conductor formed from the interlayer of the insulating layer to the surface of the insulating substrate, and the insulating layer. A wiring board comprising a connecting conductor for plating, one end of which is formed on the side surface of the insulating board, and is formed from at least one of molybdenum and tungsten and copper. The plating connection conductor is made of molybdenum or tungsten at the one end and a portion adjacent to the one end.

  The wiring board according to the present invention is characterized in that, in the above configuration, at least one of nickel, cobalt, and iron is added to a portion made of at least one of the molybdenum and tungsten in the connecting conductor for plating. To do.

  According to the multi-cavity wiring board of the present invention, the connecting conductor for plating is composed of at least one of molybdenum and tungsten at the boundary of the wiring board region and at the portion adjacent to the boundary, so that it is divided into individual wiring boards. At this time, the end surface of the connecting conductor for plating exposed on the side surface of the wiring board and the portion adjacent thereto are made of at least one of molybdenum and tungsten. Of the connection conductor for plating made of molybdenum or tungsten, the portion made of at least one of molybdenum and tungsten has a melting point of tungsten and molybdenum higher than the firing temperature and is difficult to melt. A sufficient amount of glassy material enters into a dense structure, and the anchor effect on the mother substrate is enhanced. That is, the end portion exposed when divided into individual pieces of the connecting conductor for plating is dense, and moisture hardly penetrates. Therefore, the penetration of moisture such as outside air from the end portion of the plating connection conductor between the insulating layers is effectively suppressed. Accordingly, it is possible to provide a multi-piece wiring board that can easily manufacture a highly reliable wiring board in which corrosion and migration of the wiring conductor are effectively suppressed.

  Further, according to the multi-cavity wiring board of the present invention, the wiring conductor is composed of at least one of molybdenum and tungsten having low electrical resistance and copper, and copper having low electrical resistance is included as one of the main components. This is effective in reducing the electrical resistance of the wiring conductor.

  In addition, according to the multi-cavity wiring board of the present invention, the insulating layer forming the mother board is made of an aluminum oxide sintered body having high mechanical strength, which is effective in securing the mechanical strength of the mother board. For example, it is advantageous when the mother board is made thin.

  Further, in the multi-cavity wiring board of the present invention, when at least one of nickel, cobalt, and iron is added to a portion made of at least one of molybdenum and tungsten among the connection conductors for plating, Sinterability improves and the electrical resistance (conducting resistance) of the connection conductor for plating can be suppressed further.

  According to the wiring board of the present invention, since one end of the plating connection conductor is exposed on the side surface of the insulating substrate, the plating connection conductor is produced when a large number of such wiring boards are manufactured in the form of the wiring board. The exposed ends may be electrically connected to each other. Therefore, the plating layer can be easily applied to the wiring conductor by the plating current supplied to the wiring conductor via the connecting conductor for plating.

  Further, since the connecting conductor for plating is composed of at least one of molybdenum and tungsten at one end exposed on the side surface of the insulating substrate and a portion adjacent to the one end, as in the case of the multi-cavity wiring substrate, the outside air or the like It is effectively suppressed that moisture permeates into the interlayer of the insulating layer from the exposed end of the plating connection conductor. Therefore, it is possible to provide a highly reliable wiring board in which corrosion or migration of the wiring conductor is effectively suppressed.

  Further, according to the wiring board of the present invention, the wiring conductor is made of at least one of molybdenum and tungsten and copper, and contains copper having a low electric resistance as one of the main components. It is effective for keeping it low.

  In addition, according to the wiring board of the present invention, since the insulating layer forming the insulating substrate is made of an aluminum oxide sintered body having high mechanical strength, it is effective in securing the mechanical strength of the insulating substrate, For example, it is advantageous when the insulating substrate is to be thinned.

  Further, in the wiring board of the present invention, when at least one of nickel, cobalt, and iron is added to a portion made of at least one of molybdenum and tungsten in the connecting conductor for plating, the sinterability at this portion is added. This improves the conduction resistance of the connecting conductor for plating.

(A) is a top view which shows an example of embodiment of the multi-piece wiring board of this invention, (b) is sectional drawing in the AA of (a). It is a principal part enlarged plan view (perspective view) which expands and shows the principal part of the multi-cavity wiring board shown in FIG. (A) is a perspective view showing a wiring board obtained by dividing the multi-piece wiring board shown in FIG. 1 into individual pieces, and (b) is an exploded perspective view of the wiring board shown in (a). (A) is a top view which shows an example of embodiment of the wiring board of this invention, (b) is sectional drawing in the BB line of (a).

  A multi-piece wiring board of the present invention will be described with reference to the accompanying drawings.

  FIG. 1A is a plan view showing an example of an embodiment of a multi-cavity wiring board according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA of FIG. FIG. 2 is an enlarged plan view (perspective view) showing an essential part of the multi-piece wiring board shown in FIG.

  In FIGS. 1 and 2, 1 is a mother board formed by laminating a plurality of insulating layers 1a, 2 is a wiring board region, 3 is a wiring conductor, and 4 is a connecting conductor for plating. A plurality of wiring board regions 2 are arranged on the mother board 1 vertically and horizontally, and the wiring conductors 3 of the adjacent wiring board areas 2 are electrically connected to each other through the connecting conductors 4 for plating. Basically composed. The wiring conductor 3 is shown with a detailed pattern omitted for easy viewing of the drawing.

  The mother substrate 1 has a flat plate shape, for example, and is formed by laminating a plurality of rectangular flat plate-like insulating layers 1a made of an aluminum oxide sintered body. In the example shown in FIG. 1, the mother substrate 1 is formed by laminating four insulating layers 1 a, but the number of laminated layers (two or more) may be other than this.

  The wiring board region 2 is a region serving as a wiring board for mounting an electronic component (not shown) such as a semiconductor element or a surface acoustic wave element. For example, in the central portion of each upper surface Electronic components are mounted.

  Electronic components mounted on the wiring board area 2 (individual wiring board) include semiconductor integrated circuit elements such as IC and LSI, LED (light emitting diode), PD (photodiode), CCD (charge coupled device), etc. Semiconductor elements including optical semiconductor elements, piezoelectric elements such as surface acoustic wave elements and crystal resonators, capacitive elements, resistors, micromachines (so-called MEMS elements) in which minute electromechanical mechanisms are formed on the surface of a semiconductor substrate, etc. There are various electronic parts.

In the wiring board region 2, a wiring conductor 3 is formed from the interlayer of the insulating layer 1a to the surface such as the upper surface and the lower surface. Of the wiring conductor 3, an electrode of an electronic component is electrically connected to a portion formed on the upper surface of the wiring board region 2 through solder, a bonding wire, or the like. For example, if the wiring conductor 3 formed on the lower surface of the wiring board region 2 is electrically connected to an external electric circuit (not shown) via solder or the like after being divided into individual wiring boards, the electronic component And an external electric circuit are electrically connected via the wiring conductor 3. A part of the wiring conductor 3 is a through conductor (no symbol) filled in a through hole (no symbol) penetrating the insulating layer 1a in the thickness direction. Through this through conductor, portions of the wiring conductor 3 formed on the interlayer of the insulating layer 1a and on the surface of the wiring board region 2 are electrically connected to each other vertically.

  The wiring conductor 3 is made of at least one of molybdenum and tungsten and copper. Copper is a portion that functions as a main conductor in the wiring conductor 3. Molybdenum and tungsten particles are dispersed in the copper matrix to form the wiring conductor 3. Molybdenum and tungsten are added to copper in order to enable simultaneous firing with the insulating layer 1a made of an aluminum oxide sintered body.

  For example, when the wiring conductor 3 is made of molybdenum and copper, the mother board 1 having these wiring conductors 3 is manufactured as follows.

  First, raw material powders such as aluminum oxide, silicon oxide, calcium oxide, and manganese oxide are kneaded with an organic solvent and a binder, and then formed into a sheet shape by a forming method such as a doctor blade method or a lip coater method, and a plurality of ceramic green sheets Is made. Next, copper powder and molybdenum powder were kneaded with an organic solvent and a binder to prepare a metal paste, and this metal paste was formed in advance on the surface of the ceramic green scene sheet with a predetermined wiring conductor 3 pattern. Apply or fill in through-holes (unsigned). Then, if these ceramic green sheets are laminated and then fired at about 1300 ° C., the insulating layer 1a is laminated, and the mother substrate 1 on which the wiring conductor 3 is formed from the interlayer of the insulating layer 1a to the surface is manufactured. Can do.

  In the manufacture of the mother substrate 1 described above, it is possible to perform firing at a relatively low temperature of about 1300 ° C. by adding manganese oxide to the raw material powder forming the mother substrate 1. Further, as described above, since the wiring conductor 3 contains molybdenum in addition to copper, the wiring conductor 3 and the mother substrate 1 can be simultaneously fired at the firing temperature exceeding the melting point of copper.

  In this case, the content of manganese oxide may be set to about 2.0 to 8.0% by mass. Moreover, what is necessary is just to set the content of molybdenum and tungsten in the wiring conductor 3 to about 40-60 volume%.

  Further, when the metal paste to be the wiring conductor 3 is manufactured, for example, copper powder having a particle diameter of 4.5 to 6.0 μm is used, and molybdenum or tungsten powder having a particle diameter of 2.0 to 2.7 μm is used. do it.

  The wiring conductors 3 in the adjacent wiring board regions 2 are electrically connected to each other via a plating connecting conductor 4 formed beyond the boundary 2a of the wiring board region 2 between the insulating layers 1a. Thus, by electrically connecting the wiring conductors 3 of the plurality of wiring board regions 2 to each other, a plating layer (not shown) can be simultaneously deposited on these wiring conductors 3 by electrolytic plating. Can do.

The plating connection conductor 4 is made of at least one of molybdenum and tungsten at the boundary 2a of the wiring board region 2 and at a portion adjacent to the boundary 2a. The boundary 2a of the wiring board region 2 and the portion adjacent to the boundary 2a are divided into the wiring boards 10 when the multi-piece wiring board 9 is divided into pieces of wiring boards 10 as shown in FIG. The end surface exposed on the side surface of the substrate and the portion adjacent to the exposed end surface. FIG. 3A is a perspective view showing an individual wiring board 10 produced by dividing the multi-cavity wiring board 9 shown in FIG. 1 at the boundary 2a of the wiring board region 2, and FIG. FIG. 4 is an exploded perspective view showing the wiring board 10 shown in FIG. 3A in an exploded manner between the layers where the plating connection conductors 4 are formed. In FIG. 3, the same parts as those in FIG.

  Of the connecting conductor 4 for plating, the portion made of at least one of molybdenum and tungsten has a melting point of tungsten and molybdenum higher than the firing temperature and is difficult to melt. The vitreous material enters into a dense structure, and the anchor effect on the mother substrate 1 is enhanced. That is, the end face exposed when the connecting conductor 4 for plating 4 is divided into individual pieces and the portion adjacent to the exposed end face are dense and moisture hardly penetrates. Therefore, when it is divided into individual pieces, it is effectively suppressed that moisture such as outside air permeates between the exposed portions of the plating connection conductor 4 and between the insulating layers 1a. Therefore, it is possible to provide a multi-piece wiring board 9 that can easily manufacture a highly reliable wiring board 10 in which corrosion and migration of the wiring conductor 3 are effectively suppressed.

  In addition, the part which consists of at least one of molybdenum and tungsten among the connection conductors 4 for plating consists of what consists only of tungsten, consists only of molybdenum, or consists of tungsten and molybdenum. A portion made of at least one of molybdenum and tungsten in the connection conductor 4 for plating is advantageous in terms of productivity, cost, etc., when it is made of only molybdenum or only tungsten.

  Moreover, according to such a multi-piece wiring board 9, since the wiring conductor 3 is made of at least one of molybdenum and tungsten and copper and contains copper having a low electrical resistance as one of the main components, This is effective for keeping the electrical resistance of the conductor 3 low.

  For example, in the case of the wiring conductor 3 having a thickness of about 20 μm and a line width of about 100 to 250 μm, which is frequently used in the wiring board 10 for mounting electronic components, the molybdenum and tungsten contents are about When it is 40 to 60% by volume, the electrical resistance is suppressed to about 0.002 to 0.003Ω / □ in terms of sheet resistance. In contrast, in the case of a multi-piece wiring board (not shown) in which a wiring conductor (not shown) is formed only by molybdenum or tungsten according to the prior art, the electrical resistance is about 0.008 mΩ / □ in sheet resistance. To be relatively high with the degree.

  Moreover, according to such a multi-piece wiring board 9, since the insulating layer 1a forming the mother board 1 is made of an aluminum oxide sintered body having high mechanical strength, the mechanical strength of the mother board 1 is ensured. For example, it is effective when the mother board 1 is thinned.

  For example, in the case of a mother substrate 1 (thickness of about 1 mm) in which four insulating layers 1a made of an aluminum oxide sintered body having the above-described configuration are laminated, the mechanical strength is about bending strength. About 400 MPa, Young's modulus is about 260 GPa. On the other hand, for example, a comparative mother substrate (not shown) having the same dimensions as the above-described mother substrate 1 was prepared using a glass ceramic sintered body mainly composed of aluminum oxide and borosilicate glass. In this case, the mechanical strength of the comparative mother substrate is about 150 to 170 MPa in bending strength and about 75 to 85 GPa in Young's modulus.

A portion made of at least one of molybdenum and tungsten in the connection conductor 4 for plating was prepared by adding and kneading an organic solvent and a binder to molybdenum or tungsten powder, or a mixture of molybdenum powder and tungsten powder. Formed by printing a metal paste on the surface of the ceramic green sheet to be the mother substrate 1 in a pattern in contact with the metal paste to be the wiring conductor 3 printed on the surface, and then co-firing with the ceramic green sheet can do. In the case of this connecting conductor 4 for plating,
The particle size of the molybdenum or tungsten powder used may be, for example, about 2.0 to 2.7 μm.

  Further, the connection conductor 4 for plating needs to be made of molybdenum or tungsten at the boundary 2a and the portion adjacent to the boundary 2a of the wiring board region 2, but the other portions are the same as the wiring conductor 3. It may be made of at least one of molybdenum and tungsten and copper. In this case, it is advantageous to increase the efficiency of supplying the plating current to the wiring conductor 3 by keeping the resistance of the plating connection conductor 4 low. Further, the plating connection conductor 4 may be made of molybdenum or tungsten over its entire length. In this case, all of the plating connection conductors 4 can be formed by printing the same metal paste.

  Of the connecting conductor 4 for plating, the portion that needs to be made of molybdenum or tungsten is the boundary 2a of the wiring board region 2 and the portion adjacent to the boundary 2a as described above. The portion adjacent to the boundary 2a is, for example, in a range of about 0.2 mm from the boundary 2a of the wiring board region 2 if the longitudinal cross section of the plating connection conductor 4 has the above dimensions.

The connecting conductor 4 for plating has, for example, a thickness of about 0.01 to 0.025 mm and a line width of about 0.1 to 0.2 mm, and an area corresponding to this longitudinal section (about 0.001 to 0.005 mm ² ) The end face generated with the division of the substrate 1 is exposed on the side surface of the individual wiring board 10.

  The connecting conductor 4 for plating electrically connects the wiring conductors 3 beyond the boundary 2a of the wiring board region 2, and the plating layer is formed by electrolytic plating on the exposed surface of the wiring conductor 3 in the multi-piece wiring board 9. It is for facilitating the deposition. Therefore, in the example shown in FIG. 2, in order to keep the electrical resistance low and to shorten the unnecessary plating connection conductor 4 remaining in the piece of wiring board 10 as much as possible, between the adjacent wiring board regions 2. It is formed with a linear pattern. Note that the plating connection conductor 4 may be formed in a polygonal or curved pattern according to the convenience of the pattern of the wiring conductor 3, the shape and dimensions of the wiring board region 2, and the like.

  And the wiring conductor 3 of each wiring board area | region 2 electrically connected mutually via the connection conductor 4 for plating supplies the electric current for plating to a part of the connection conductor 4 for plating in electroplating liquid. Thus, a plating layer (not shown) can be deposited on the exposed surface. The plating current is supplied to the plating connection conductor 4 by providing, for example, a connection terminal (not shown) on the outer peripheral portion of the mother board 1 (dummy region 5). The current may be extended to the terminal and electrically connected, and the current may be supplied to the terminal from a power source (not shown) such as a rectifier via a plating jig (not shown).

Examples of the plating layer include metal materials such as nickel, cobalt, gold, palladium, copper, and tin, or alloys of these metal materials. For example, if the individual wiring board 10 is used as an electronic component mounting board and solder, bonding wires, or the like are connected to the exposed surface of the wiring conductor 3, the thickness increases in order from the exposed surface of the wiring conductor 3. A nickel plating layer having a thickness of about 1 to 15 μm and a gold plating layer having a thickness of about 0.5 to 2 μm may be deposited.

  After the plating layer is deposited on the exposed surface of the wiring conductor 3, if the mother board 1 is divided along the boundary 2 a of the wiring board region 2, a large number of individual wiring boards 10 for mounting electronic components and the like are produced. Is done. The mother board 1 may be divided after electronic components are mounted on the upper surface of the wiring board region 2 or the like.

  In this case, the division of the mother board 1 is performed by, for example, forming a dividing groove (no symbol) on the upper and lower surfaces of the mother board 1 along the boundary 2a of the wiring board region 2 as shown in FIG. It can be performed by a method of applying a stress to the mother substrate 1 at the groove and causing it to break, or a method of cutting such as dicing. Such a dividing groove is formed by making a cut with a cutter blade or the like at a predetermined depth along the boundary 2a of the wiring board region 2 on the upper surface and the lower surface of the multilayer body of ceramic green sheets to be the mother substrate 1. be able to. By this division, the connecting conductor 4 for plating that electrically connected the wiring conductors 3 in the wiring board region 2 between the insulating layers 1a, that is, inside the mother board 1, is cut or broken at the boundary 2a. The cut or broken end portion is exposed on the side surface of the individual wiring board 10.

Here, the effect of suppressing the permeation of moisture in the multi-piece wiring board 9 in which the plating connection conductor 4 is made of molybdenum or tungsten within a range of about 0.1 mm from the boundary 2a of the wiring board region 2 is specifically described. explain. In this specific example, the mother substrate 1 was formed by laminating four insulating layers 1a having a thickness of about 0.2 mm and having a square shape with a side length of about 100 mm in plan view. In addition, the wiring board region 2 has a square shape with a side length of about 7.5 mm and is arranged on the mother board 1 in 12 × 12 rows vertically and horizontally. A plurality of wiring conductors 3 having a line width of about 0.1 mm were formed in the wiring board region 2 (interlayer of the insulating layer 1a) and on the surface thereof with the adjacent interval set to about 0.1 mm. The connecting conductor 4 for plating has a thickness of about 0.02 mm, a line width of about 0.1 mm, and a length of about 0.2 mm, and is formed of molybdenum over the entire length. With respect to the multi-piece wiring board 9 of this specific example, a nickel plating layer and a gold plating layer are sequentially deposited on the exposed surface of the wiring conductor 3 by electrolytic plating, and then divided into a plurality of individual wiring boards 10. Each piece of the wiring board 10 was allowed to stand for 1000 hours at high temperature and high humidity (85 ° C., 85%), and the presence or absence of corrosion and migration of the wiring conductor 3 was confirmed by a 10 × microscope. As a result, neither corrosion nor migration was confirmed in the wiring board 10 produced using the multi-cavity wiring board 9 of the above specific example. On the other hand, in the case of a multi-piece wiring board (not shown) produced by a conventional technique, that is, a technique of forming a connecting conductor for plating (not shown) with at least one of molybdenum and tungsten and copper. In the same test as above, corrosion or migration occurred at an occurrence rate of about 0.5%.

  In addition, in order to suppress the resistance at the time of sending the plating current to the wiring conductor 3, it is preferable that the plating connection conductor 4 has a longitudinal section responsibility of a certain value or more, but it suppresses moisture penetration. Therefore, it is better to make the width wider than to increase the thickness. This is because if the thickness of the plating connection conductor 4 becomes too thick, the adhesion between the upper and lower insulating layers 1a tends to be hindered by the plating connection conductor 4, and between these layers, the plating connection conductor tends to be lowered. This is because moisture may easily permeate from between 4 and the insulating layer 1a.

  Further, when a part of the connection conductor 4 for plating (the boundary 2a of the wiring board region 2 or the like) is made of molybdenum or tungsten and the other part is made of at least one of molybdenum and tungsten and copper. For example, at the time of printing the metal paste to be the plating connection conductor 4 described above, the printing may be performed such that the end portions of both metal pastes overlap each other.

  In addition, in the multi-piece wiring board 9, when at least one of nickel, cobalt, and iron is added to a portion made of at least one of molybdenum and tungsten in the connection conductor 4 for plating, Sinterability improves and the conduction | electrical_connection resistance of the connection conductor 4 for plating can be restrained lower.

  Therefore, current loss during plating is suppressed, which is advantageous in terms of productivity and cost. Moreover, the variation in the current supplied to each wiring board region 2 can be further suppressed, and the variation in the thickness of the plating layer can be further suppressed.

  Nickel, cobalt, and iron (at least one type) can be plated by adding these metal material powders to the above-described metal paste that will be the connecting conductor 4 for plating, and simultaneously firing the ceramic green sheet or the like at about 1300 ° C. It can be contained in the connection conductor 4 for use.

  In this case, nickel, cobalt, and iron have a melting point of about 1450 to 1540 ° C., which is close to the firing temperature (about 1300 ° C.), compared to molybdenum and tungsten, and have higher sintering properties than molybdenum and tungsten. Therefore, the electrical resistance of the plating connection conductor 4 can be kept low. In addition, since the melting point is higher than the firing temperature, it is difficult to melt at the time of firing, so that effects such as densification by vitreous and anchor effect on the mother substrate 1 can be sufficiently obtained.

  The particle size of the powder of nickel, cobalt and iron (hereinafter referred to as nickel) may be set to the same or slightly smaller than the particle size of molybdenum and tungsten, for example. If the particle size is about this level, the sinterability of molybdenum and tungsten (powder) and nickel or the like (powder) is increased, and the sinterability of the metal paste used as the connection conductor 4 for plating is further increased. It is advantageous.

  Moreover, in order to acquire said effect effectively, the addition amount of nickel etc. in the connection conductor 4 for plating should just be about 0.1-5 volume%.

  Nickel or the like may be added to the metal paste as a powder of these oxides. When added as such an oxide powder, the bond with the ceramic green sheet containing an oxide such as aluminum oxide or silicon oxide can be further strengthened.

  When nickel or the like is included in the connecting conductor 4 for plating as described above, the corrosion resistance, the ease of handling (workability) when producing the metal paste, the sinterability with tungsten and molybdenum, and the like are taken into consideration. For example, it is preferable to select nickel.

  When a plurality of connecting conductors 4 for plating are formed in one wiring board region 2, the boundary 2a of the wiring board region 2 and the portion adjacent to the boundary 2a (from at least one of molybdenum and tungsten) It is not necessary that the portion) is unified with or without nickel added.

  For example, when the wiring conductor 3 having a relatively large area and the wiring conductor 3 having a relatively small area are formed in one wiring board region 2 as in the example illustrated in FIG. 2, the wiring conductor having a relatively large area. Only the connection conductor 4 for plating connected to 3 may be added with nickel or the like as described above. In this case, the labor and cost of adding nickel or the like can be reduced while facilitating the supply of the plating current to the wiring conductor 3 that has a relatively large area and requires a large amount of plating current.

  Next, the wiring board of the present invention will be described. The wiring board of the present invention is produced, for example, by dividing the multi-cavity wiring board 9 of the present invention along the boundary 2 a of the wiring board region 2. In the following description, the description of the same matters as the multi-cavity wiring board 9 is omitted.

FIG. 4A is a plan view showing an example of an embodiment of the wiring board of the present invention, and FIG. 4B is a cross-sectional view taken along the line BB in FIG. The wiring board 10 of the example of this embodiment is manufactured by breaking (dividing) the multi-piece wiring board 9 shown in FIG. 1 along the dividing groove formed in the boundary 2a of the wiring board region 2. is there. FIG. 3 is a perspective view of the wiring board shown in FIG.

  In FIG. 4, 11 is an insulating substrate formed by laminating a plurality of insulating layers 1a, 3 is a wiring conductor, and 4 is a connecting conductor for plating. A wiring conductor 3 is formed on the insulating substrate 1, and a plating connecting conductor 4 connected to the wiring conductor 3 is formed between the insulating layers 1a to basically constitute the wiring substrate 10. In FIG. 4, the wiring conductor 3 is shown with a detailed pattern omitted.

  The insulating substrate 1 has a flat plate shape such as a square flat plate shape, and is formed by laminating a plurality of square flat plate insulating layers 1a made of an aluminum oxide sintered body. In the example shown in FIG. 4, four insulating layers 1a are laminated to form the insulating substrate 10. However, the number of laminated layers (two or more) may be other than this.

  The insulating substrate 11 is for mounting various electronic components (not shown) such as the semiconductor elements and piezoelectric elements, and the electronic components are mounted on an exposed surface such as a central portion of the upper surface.

  Similar to the wiring board region 2 of the multi-piece wiring board 9, the wiring conductor 3 is formed on the insulating board 11 from the interlayer of the insulating layer 1a to the surface such as the upper surface and the lower surface. Of the wiring conductor 3, an electrode of an electronic component is electrically connected to a portion formed on the upper surface of the insulating substrate 10. If the wiring conductor 3 formed on the lower surface of the insulating substrate 11 is electrically connected to an external electric circuit (not shown), the electronic component and the external electric circuit are electrically connected via the wiring conductor 3. The Also in this example, a part of the wiring conductor 3 is a through conductor (no symbol).

  The insulating substrate 11 is manufactured by dividing the mother substrate 1 of the multi-piece wiring substrate 9 along the boundary 2 a of the wiring substrate region 2. That is, a raw material powder such as aluminum oxide is used in the same manner as described above, and a plurality of ceramic green sheets produced by the same method are laminated and then fired to produce the mother substrate 1. If the mother substrate 1 is divided along the dividing grooves formed on the upper and lower surfaces, the insulating substrate 11 of the wiring substrate 10 can be manufactured. Note that the insulating substrate 11 of the wiring substrate 10 can also be fired at a relatively low temperature of about 1300 ° C. by adding manganese oxide to the raw material powder. The content of manganese oxide may be set to about 2.0 to 8.0% by mass.

  The wiring conductor 3 is made of the same material as in the case of the multi-piece wiring board 9, that is, at least one of molybdenum and tungsten (particles) and copper (main conductor), and molybdenum or tungsten particles are contained in the copper matrix. Is distributed. Since the wiring conductor 3 contains molybdenum in addition to copper, simultaneous firing with the mother substrate 1 at a firing temperature exceeding the melting point of copper is possible.

  A plating layer (not shown) such as nickel or gold is deposited on the exposed surface of the wiring conductor 3. The connection conductor 4 for plating electrically connects the wiring conductors 3 in adjacent wiring board regions 2 to each other when the wiring board 10 is manufactured in the form of a multi-piece wiring board 9 as shown in FIG. It is for keeping. The wiring conductors 3 of the plurality of wiring board regions 2 are electrically connected to each other by the plating connection conductor 4 and the plating layer is deposited by an electrolytic plating method.

  The connection conductor 4 for plating is for supplying a current for plating to the wiring conductor 3 in the multi-piece wiring board 9, but also remains on the insulating layer 1a in the individual wiring board 10. Yes.

The plating connection conductor 4 needs to be directly connected to the wiring conductor 3 for the above function, and one end thereof needs to be exposed on the side surface of the insulating substrate 11. One end of the connection conductor 4 for plating exposed on the side surface of the insulating substrate 11 corresponds to a portion located on the boundary 2 a of the wiring board region 2 in the multi-piece wiring board 9.

  One end of the connecting conductor 4 for plating exposed on the side surface of the insulating substrate 11 and a portion adjacent to the one end are made of molybdenum or tungsten. As in the case of the connection conductor 4 for plating in the multi-piece wiring board 9, this portion has a dense structure and has a high anchor effect on the insulating substrate 11. In other words, one end of the plating connection conductor 4 exposed on the side surface of the insulating substrate 11 and a portion adjacent to the one end are dense, and moisture hardly penetrates. Therefore, the penetration of moisture such as outside air from the exposed end of the plating connection conductor 4 into the interlayer of the insulating layer 1a is effectively suppressed. Therefore, it is possible to provide a highly reliable wiring board 10 in which corrosion and migration of the wiring conductor 3 are effectively suppressed.

  Further, according to such a wiring board 10, since the wiring conductor 3 is made of at least one of molybdenum and tungsten and copper and contains copper having a low electric resistance as one main component, the wiring conductor 3 It is effective in suppressing the electrical resistance to a low level (for example, about 0.002 to 0.003Ω / □ in terms of sheet resistance).

Further, according to such a wiring substrate 10, since the insulating layer 1a forming the insulating substrate 11 is made of an aluminum oxide sintered body having high mechanical strength, the mechanical strength of the insulating substrate 11 is ensured. This is effective, and is advantageous, for example, when the insulating substrate 11 is made thin. For example, if the thickness of the insulating substrate 11 is about 1 mm, the bending strength is about 400 MPa and the Young's modulus is about 260 GPa.

  Of the connecting conductor 4 for plating, a portion made of molybdenum or tungsten is a ceramic that becomes a mother substrate 1 for producing an insulating substrate 11 by using a metal paste prepared by adding an organic solvent and a binder to molybdenum or tungsten powder and kneading them. It can be formed by printing on the green sheet with a pattern in contact with the metal paste to be the wiring conductor 3 and then simultaneously firing with this ceramic green sheet.

  Also in the wiring board 10, the plating connection conductor 4 needs to be made of molybdenum or tungsten at one end exposed on the side surface of the insulating substrate 1 and at a portion adjacent to the one end. As in the case of the conductor 3, the resistance may be kept low by being made of copper and at least one of molybdenum and tungsten.

  The portions that need to be made of molybdenum or tungsten among the connection conductors 4 for plating are one end exposed on the side surface of the insulating substrate 1 and a portion adjacent to this one end as described above. The portion adjacent to one end corresponds to the length from the boundary 2a of the wiring board region 2 in the multi-piece wiring board 9, and is about 0.2 mm, for example.

As in the case of the multi-piece wiring substrate 9, the plating connection conductor 4 has a thickness of about 0.01 to 0.025 mm and a line width of about 0.1 to 0.2 mm, and an area corresponding to this longitudinal section. (
One end is exposed on the side surface of the insulating substrate 11 at about 0.001 to 0.005 mm ² .

  The plating layer to be deposited on the wiring conductor 3 may be a metal material such as nickel, cobalt, gold, palladium, copper, tin, or an alloy of these metal materials, as described above. is there.

  In the wiring substrate 10, specific examples and effects when the one end exposed on the side surface of the insulating substrate 1 and the portion adjacent to the one end of the connection conductor 4 for plating are made of tungsten or molybdenum are as described above. This is the same as the specific example in the individual wiring board 9.

  Also in the individual wiring board 10, when at least one of nickel, cobalt, and iron is added to a portion made of at least one of molybdenum and tungsten in the connection conductor 4 for plating, sintering at this portion is performed. Thus, the conduction resistance of the plating connection conductor 4 can be further reduced.

  For this reason, when a large number of wiring boards 10 are produced in the form of the wiring board 9, current loss during plating is suppressed, which is advantageous in terms of productivity and cost. Further, variation in current supplied to the plurality of wiring substrate regions 2 arranged as the wiring substrate 10 can be further suppressed. Therefore, it is possible to provide the wiring board 10 in which the variation in the thickness of the plating layer is smaller.

  Nickel, cobalt, and iron (nickel etc.) are added to the metal paste used as the connection conductor 4 for plating, and fired by adding powder of these metal materials to the multi-cavity wiring board 9 as described above. It can add to the connection conductor 4 for plating. As in the case of the multi-piece wiring board 9 described above, the presence of nickel or the like whose melting point is close to the firing temperature makes it possible to increase the sinterability of the plating connection conductor 4 and keep the electrical resistance low. Further, it is possible to sufficiently obtain effects such as densification by vitreous material and an anchor effect for the mother substrate 1.

  The nickel or the like added to the plating connection conductor 4 in this wiring board 10 is the same as that of the multi-cavity wiring board 9 described above with respect to the particle size, content, and the like. Similarly, it is preferable to select nickel in consideration of corrosion resistance and the like.

DESCRIPTION OF SYMBOLS 1 ... Mother board 1a .... Insulation layer 2 ... Wiring board area | region 2a .... Border 3 of a wiring board area ... Wiring conductor 4 ... Connection conductor 5 for plating ... Dummy area 9 ... Multiple wiring board
10 ... wiring board
11 ... Insulated substrate

Claims (4)

A plurality of insulating layers made of an aluminum oxide sintered body are laminated, and a plurality of wiring board regions are formed from the interlayer of the insulating layer to the surface of the wiring board region, in which a plurality of wiring board regions are arranged vertically and horizontally. A wiring board comprising a plurality of wiring conductors and a connecting conductor for plating formed between layers of the insulating layer and connecting the wiring conductors across a boundary of the wiring board region, And a plurality of metal-plating connecting conductors comprising at least one of molybdenum and tungsten at a boundary of the wiring board region and a portion adjacent to the boundary. Wiring board.   2. The multi-cavity wiring board according to claim 1, wherein at least one of nickel, cobalt and iron is added to a portion made of at least one of molybdenum and tungsten in the connecting conductor for plating. An insulating substrate formed by laminating a plurality of insulating layers made of an aluminum oxide sintered body, a wiring conductor formed from an interlayer of the insulating layer to a surface of the insulating substrate, and the wiring conductor between the insulating layers A wiring board comprising a connection conductor for plating formed and connected at one end to the side surface of the insulating substrate, wherein the wiring conductor is made of at least one of molybdenum and tungsten and copper, and the connection conductor for plating The wiring board is made of at least one of molybdenum and tungsten at the one end and a portion adjacent to the one end.   4. The wiring board according to claim 3, wherein at least one of nickel, cobalt, and iron is added to a portion made of at least one of molybdenum and tungsten in the connecting conductor for plating.

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