JP4373841B2 - Wiring board - Google Patents

Description

  The present invention relates to a wiring board for mounting electronic components such as semiconductor elements and capacitive elements.

  Conventionally, for example, semiconductor integrated circuit elements such as IC and LSI, LD (semiconductor laser), LED (light emitting diode), PD (photodiode), CCD, line sensor, image sensor and other optical semiconductor elements, piezoelectric vibrator, crystal vibration Wiring boards on which vibrators such as children and other various electronic components are mounted include ceramic sintered bodies such as aluminum oxide sintered bodies and glass ceramic sintered bodies (glass ceramics), epoxy resins, polyimide resins, etc. It is formed by laminating a plurality of insulating layers made of an electrically insulating material such as a composite material formed by bonding an organic resin or inorganic powder such as aluminum oxide with an organic resin such as an epoxy resin, and has an electronic component mounting portion on the upper surface. An insulating base, a wiring conductor formed inside the insulating base, and an array formed on one main surface of the insulating base and electrically connected to the wiring conductor Is a structure in which and a number of connection pads.

  The electrical connection between the wiring conductor and the connection pad is usually made through a through conductor formed so as to penetrate the insulating layer in the thickness direction from the connection pad to the wiring conductor.

  Mount the electronic component on the mounting part, connect the electrode of the electronic component to the connection pad via a connecting material such as solder or bonding wire, and seal the electronic component with a lid or sealing resin if necessary Thus, an electronic device is formed.

  In this electronic device, a part of the wiring conductor is exposed on the side surface and the lower surface of the insulating base, and the exposed portion is connected to an external electric circuit via solder or the like so that the electrode of the electronic component is connected to the connection pad and the through conductor. Are electrically connected to an external electric circuit via the wiring conductor.

In recent years, in such an electronic device, for example, downsizing and high-density mounting have been required as components to be mounted on an electronic device such as a mobile phone. Therefore, for example, flip chip mounting suitable for miniaturization has been proposed as a method for connecting electronic components. In flip chip mounting, solder bumps are respectively formed on a plurality of electrodes arranged vertically and horizontally on the main surface of an electronic component, and the electrodes are aligned with a plurality of connection pads formed on the upper surface of an insulating substrate. The solder bump is melted to connect the electrode and the connection pad. Therefore, it is necessary to form the connection pads on the wiring board so as to face the electrodes arranged vertically and horizontally on the main surface of the electronic component, and a plurality of pads are arranged vertically and horizontally at the center of one main surface of the insulating substrate. It is formed.
JP 2003-110220 A Japanese Patent Laid-Open No. 2003-017850 JP 2003-017857 A

  However, in such a conventional wiring board, there is a difference in shrinkage ratio during firing between the insulating base and the plurality of connection pads and through conductors formed on the upper surface of the insulating base. As a result, stress that deforms the insulating base occurs, and the connection pads and the through conductors that connect the connection pads to the wiring conductors are concentrated in the central portion of the insulating base. On the other hand, a stress that bends the insulating base acts on the central portion of the main surface, and this stress causes deformation of the insulating base, particularly the region where the connection pads are formed. There was a problem that a shift occurred and the mounting reliability was lowered.

  This deformation is particularly large at the outer peripheral portion of the connection pad array where stress due to a difference in shrinkage ratio during firing is greatly applied.

  The present invention has been completed in order to solve the above-described problems of the prior art, and its purpose is to firmly bond a plurality of connection pads formed on the upper surface of an insulating substrate and electrodes of an electronic component. An object of the present invention is to provide a wiring board having excellent mounting reliability.

The wiring board of the present invention has a rectangular insulating base formed by laminating a plurality of ceramic layers, a wiring conductor formed inside the insulating base, and a vertical and horizontal arrangement at the center of one main surface of the insulating base. A plurality of connection pads formed and electrically connected via the wiring conductors and through conductors, and electrically connected to the wiring conductors formed adjacent to the periphery of the plurality of connection pads. A plurality of dummy through conductors, and the plurality of connection pads have the same adjacent spacing in the vertical direction and the adjacent spacing in the horizontal direction, and are arranged in a rectangular array as a whole. The plurality of dummy through conductors are formed on an extension line of the plurality of connection pads arranged so that an adjacent interval between the dummy through conductors and the adjacent connection pads is between adjacent connection pads. And it is characterized in that it is formed so as to be the same as.

  The wiring board of the present invention is preferably characterized in that the dummy through conductor is formed in the outermost ceramic layer having the one main surface among the plurality of ceramic layers.

According to the wiring board of the present invention, a rectangular insulating base formed by laminating a plurality of ceramic layers, a wiring conductor formed inside the insulating base, and a vertical and horizontal arrangement at the center of one main surface of the insulating base A plurality of connection pads formed and electrically connected through the wiring conductor and the through conductor, and a plurality of connection pads formed adjacent to the periphery of the plurality of connection pads and not electrically connected to the wiring conductor The plurality of connection pads are formed such that the adjacent spacing in the vertical direction and the adjacent spacing in the horizontal direction are the same, and the overall arrangement is a square shape. , a plurality of dummy vias is an extension of the arrangement of a plurality of connection pads, adjacent spacing between the connection pads and the adjacent dummy vias are formed so as to be the same as the adjacent interval between the connection pads Therefore, the stress caused by the difference in shrinkage rate during firing between the insulating base, the plurality of connection pads formed on the upper surface of the insulating base and the dummy through conductor contracts to the outside of the dummy through conductor. stress since only different insulating substrates of rate exists, the difference in the shrinkage rate tends to be greatest in the dummy via conductors, also connection pads and through conductor, the portions of the outermost periphery of the arrangement of the conductors of such dummy vias Since it tends to concentrate, it concentrates on the portion where the dummy through conductor is formed, and does not become particularly large at the central portion of the one main surface of the insulating base. As a result, deformation due to shrinkage difference between the insulating base during firing, the plurality of connection pads formed on the upper surface of the insulating base, and the through conductor can be reduced, and the plurality of connections formed on the upper surface of the insulating base. Since the positions of the pads and the electrodes of the electronic component are aligned, the electronic component can be firmly bonded to the wiring substrate, and a wiring substrate excellent in mounting reliability of the electronic component can be provided.

  Even if some deformation occurs in the insulating base in the region where the dummy through conductor and the connection pad are formed, the deformation is mainly limited to the outer portion where the dummy through conductor is formed. It is possible to effectively prevent the insulating base from being deformed in the region where the connection pad for connecting the electronic component is formed, and the electrode of the electronic component can be opposed to the connection pad and reliably connected.

In the wiring board of the present invention , the plurality of connection pads are formed so that the adjacent distance in the vertical direction and the adjacent distance in the horizontal direction are the same and are arranged in a square shape as a whole, The plurality of dummy through conductors are formed on the extended line of the plurality of connection pads so that the adjacent interval between the dummy through conductor and the adjacent connection pad is the same as the adjacent interval between the connection pads. since, connection pads easily outermost affected shrinkage during firing, shrinkage difference is absorbed effectively by the plurality of dummy via conductors not connected to the wiring conductor and electrical, position shift sequences securely Alleviated.

  In addition, since the adjacent interval between the dummy through conductor and the adjacent connection pad is formed so as to be the same as the adjacent interval between the connection pads, the influence of the shrinkage is affected by the electrical connection with the outermost wiring conductor. Therefore, it is applied uniformly to the plurality of connection pads connected to each other.

  In the wiring board of the present invention, preferably, the dummy through conductor is formed in the outermost ceramic layer having one main surface among the plurality of ceramic layers, so that the dummy through conductor is formed inside the insulating base. Since it is possible to secure a region where the wiring conductor can be formed without being hindered, it is possible to increase the density of the wiring as in the conventional wiring board.

  The wiring board of the present invention will be described below with reference to the drawings. FIG. 1A is a plan view showing an example of an embodiment of a wiring board according to the present invention, and FIG. 1B is a sectional view thereof. In FIG. 1, 1 is an insulating substrate, 2 is a connection pad, 3 is a wiring conductor, and 6 is a dummy through conductor. The insulating substrate 1, the connection pad 2, the wiring conductor 3, and the dummy through conductor 6 basically constitute the wiring board 9 of the present invention.

  The insulating substrate 1 is an aluminum oxide sintered body, a glass ceramic sintered body (glass ceramic), an aluminum nitride sintered body, a ceramic sintered body such as a mullite sintered body, or an organic resin such as an epoxy resin or a polyimide resin. Alternatively, a plurality of insulating layers 1a made of an electrical insulating material such as a composite material formed by bonding inorganic powder such as aluminum oxide with an organic resin such as an epoxy resin are stacked.

  For example, when each insulating layer 1a is made of an aluminum oxide sintered body, the insulating base 1 is in the form of a mud by adding and mixing an appropriate organic binder and solvent to raw material powders such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide. A plurality of ceramic green sheets (ceramic raw sheets) are obtained by using a sheet forming technique such as a doctor blade method and a calender roll method to obtain a plurality of ceramic green sheets. The ceramic green sheet is formed into an appropriate shape by cutting or punching, and these ceramic green sheets are laminated to form a laminated body. Finally, the laminated body is fired in a reducing atmosphere at a temperature of about 1600 ° C. for insulation. The substrate 1 is manufactured.

  The insulating base 1 has, for example, a semiconductor integrated circuit element such as an IC or LSI, an optical semiconductor element such as an LD (semiconductor laser), an LED (light emitting diode), a PD (photodiode), a CCD, a line sensor, or an image sensor. And a mounting portion (not shown) for mounting a vibrator such as a piezoelectric vibrator and a crystal vibrator and other various electronic components.

  In addition, a connection pad 2 is formed at the center of one main surface (upper surface in FIG. 1B) of the insulating base 1, and a wiring conductor 3 is formed inside the insulating base 1 (between the ceramic layers 1a). Has been. In the example of FIG. 1, the connection pad 2 and the wiring conductor 3 are electrically connected through a through conductor 4 formed so as to penetrate the ceramic layer 1a in the thickness direction.

  A plurality of electrodes arranged vertically and horizontally on the main surface of an electronic component (not shown) mounted on the central portion of one main surface of the insulating substrate 1 are opposed to the connection pads 2 so as to be conductive such as solder. Electrical connection is made through a connecting material (not shown), and a part of the wiring conductor 3 is exposed on the side surface or the lower surface of the insulating base 1 so that the electrodes of the electronic component are connected to the connection pad 2 and the wiring. It is led out to the side surface and the lower surface of the insulating substrate 1 through the conductor 3. By electrically connecting the lead-out portion of the wiring conductor 3 to the external electric circuit via solder or the like, the electrode of the electronic component is electrically connected to the external electric circuit via the connection pad 2 and the wiring conductor 3. The

  In addition, the insulating base 1 is provided with a dummy through conductor 6 not electrically connected to the wiring conductor 3 adjacent to the entire periphery of the plurality of connection pads 2 on one main surface (upper surface). With this configuration, the stress generated due to the difference in shrinkage rate during firing between the insulating base 1 and the plurality of connection pads 2 and the through conductors 4 formed on the upper surface of the insulating base 1 is caused by the dummy through conductor 6. Since there is only the insulating base body 1 having a different shrinkage ratio outside, the difference between the shrinkage ratios of the dummy penetrating conductor 6 tends to be the largest, and the conductors such as the connection pad 2, the penetrating conductor 4, and the dummy penetrating conductor 6 Since stress tends to concentrate on the outermost peripheral portion of the line, it concentrates on the portion where the dummy through conductors 6 are formed, and does not become particularly large at the central portion of one main surface of the insulating base 1. As a result, the deformation due to the shrinkage difference between the insulating base 1 during firing, the plurality of connection pads 2 formed on the upper surface of the insulating base 1, and the through conductors 4 can be alleviated and formed on the upper surface of the insulating base 1. Since the positions of the plurality of connection pads 2 and the electrodes of the electronic component are aligned, the electronic component can be firmly bonded to the wiring substrate 9, and the wiring substrate 9 having excellent mounting reliability of the electronic component can be provided. it can.

  Further, even if some deformation occurs in the insulating base 1 in the region where the dummy through conductor 6 and the connection pad 2 are formed, the deformation is mainly applied to the outer portion where the dummy through conductor 6 is formed. Since it is limited, it is effectively prevented that the insulating substrate 1 is deformed in the region where the connection pad 2 for connecting the electronic component is formed, and the electrode of the electronic component is opposed to the connection pad 2. It can be securely connected.

  In this case, when the distance between the dummy penetrating conductor 6 and the connection pad 2 is increased, or when the dummy through conductor 6 is only partially adjacent to the arrangement of the connection pads 2, the action of alleviating the deformation of the insulating substrate 1 is achieved. Since it becomes insufficient or biased, the insulating substrate 1 is deformed in the region where the connection pad 2 is formed.

  For this reason, the distance between the dummy through conductor 6 and the connection pad 2 is preferably not more than twice the adjacent interval between the connection pads 2, and electrical insulation between the dummy through conductor 6 and the connection pad 2 can be ensured. Considering it, it is more preferable to set it to 2 times or less and 50 μm or more. The dummy through conductors 6 are preferably formed in the same number as the connection pads 2 along the outermost periphery of the adjacent connection pads 2.

  The dummy penetrating conductor 6 may be formed on the end surface exposed on the one main surface side of the insulating base 1 so as to cover the end surface and to form the dummy connection pad 5 having substantially the same shape and size as the connection pad 2. preferable. In this case, moisture or the like in the outside air can be reliably prevented from entering the inside of the insulating base 1 from a minute gap between the side surface of the dummy through conductor 6 and the insulating base 1. Since oxidation corrosion, migration, and the like of the wiring conductor 3 can be effectively prevented, the long-term reliability as the wiring board 9 on which electronic components are mounted can be further improved.

  Further, if the dummy connection pad 5 is formed, at least one main surface of the insulating substrate 1 has a structure approximate to the structure composed of the connection pad 2 and the through conductor 4 by the dummy through conductor 6 and the dummy connection pad 5. And can be formed in the ceramic layer 1a immediately below. As a result, it is possible to more reliably disperse the stress caused by the difference in shrinkage rate during firing between the connection pad 2 and the insulating base 1 and between the through conductor 4 and the insulating base 1 over the entire one main surface of the insulating base 1. Therefore, the deformation of the insulating substrate 1 in the region where the connection pad 2 is formed can be more effectively prevented.

  In addition, the wiring conductor 3, the connection pad 2, the through conductor 4, the dummy connection pad 5, and the dummy through conductor 6 are made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, and the like. , Formed on the ceramic layer 1a of the insulating substrate 1 in the form of a metal foil, a plating layer, or the like.

  For example, when the wiring conductor 3, the connection pad 2, the through conductor 4, the dummy connection pad 5 and the dummy through conductor 6 are made of a copper metallized conductor, a metal paste prepared by adding an organic solvent, a resin binder, or the like to copper powder. Is formed by printing, filling and filling the surface of the ceramic green sheet to be the ceramic layer 1a or the inside of the through hole previously punched and formed in the ceramic green sheet.

  The dummy penetrating conductor 6 preferably has the same or larger shape and size in the cross section than the shape and size in the cross section of the penetrating conductor 4. For example, when the dummy penetrating conductor 6 and the penetrating conductor 4 both have a circular cross-sectional shape, the diameters of both of them should be the same or the dummy penetrating conductor 6 should be larger. As a result, a greater stress is applied to the dummy penetrating conductor 6, and deformation of the central portion of the insulating base 1 on which the penetrating conductor 4 and the connection pad 2 are formed can be prevented more reliably. In this case, in consideration of ensuring the mechanical strength of the insulating substrate 1 in the portion where the dummy through conductor 6 is formed, the dummy through conductor 6 has a diameter equal to or greater than that of the through conductor 4 and equal to or less than 150 μm. In addition, it is more preferable to secure an adjacent interval of 50 μm or more.

Further, in the wiring board 9 of the present invention , the plurality of connection pads 2 are formed such that the adjacent spacing in the vertical direction and the adjacent spacing in the horizontal direction are the same and are arranged in a square shape as a whole. In the plurality of dummy through conductors 6, the adjacent interval between the dummy through conductor 6 and the adjacent connection pad 2 is the same as the adjacent interval between the connection pads 2 on the extended line of the plurality of connection pads 2. way that has been formed. With this configuration, the plurality of connection pads 2 that are electrically connected to the outermost wiring conductor 3 that is susceptible to shrinkage during firing are contracted by the plurality of dummy through conductors 6 that are not electrically connected to the wiring conductor 3. the difference is reduced misalignment of the array are absorbed Runode, it is possible to provide a wiring board 9 having excellent more mounting reliability.

In the wiring board 9 of the present invention, the dummy through conductor 6 is preferably formed on the outermost ceramic layer 1a having one main surface among the plurality of ceramic layers 1a. With this configuration, an area in which the wiring conductor 3 can be formed without being obstructed by the dummy through conductor 6 can be secured inside the insulating base 1. Densification is possible.

  And in the wiring board 9 of this invention, while mounting an electronic component on the upper surface of the insulating base | substrate 1, the electrode of an electronic component is electrically connected to the connection pad 2, and a lid or sealing is carried out as needed. An electronic device is formed by sealing with a resin or the like. This electronic device is used as a component of electronic equipment such as a small and high-precision mobile phone.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

(A), (b) is the top view and sectional drawing which show an example of embodiment of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 1a ... Ceramic layer 2 ... Connection pad 3 ... Wiring conductor 4 ... Through conductor 5 ... Dummy connection pad 6 ... Dummy through conductor 9 ... Wiring board

Claims (2)

A rectangular insulating base formed by laminating a plurality of ceramic layers; a wiring conductor formed inside the insulating base; and a wiring conductor formed vertically and horizontally at a central portion of one main surface of the insulating base; A plurality of connection pads electrically connected through the through conductors, and a plurality of dummy through conductors formed adjacent to the periphery of the plurality of connection pads and not electrically connected to the wiring conductor; The plurality of connection pads are formed such that the adjacent spacing in the vertical direction and the adjacent spacing in the horizontal direction are the same and are arranged in a square shape as a whole. The dummy penetrating conductor has an adjacent interval between the dummy penetrating conductor and the adjacent connecting pad on the extension line of the plurality of connecting pads arranged to be the same as the adjacent interval between the connecting pads. Wiring board, characterized by being formed Te. It said dummy through conductor, the wiring board according to claim 1 Symbol mounting, characterized in that it is formed on the ceramic layer of the outermost layer having the one main surface of the plurality of ceramic layers.

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