JP2005311254A - Wiring board and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board which is mounted with an electronic component on the top face thereof and packaged on an external electric circuit board mounted with electronic elements which easily allows further reduction in the size of the external electric circuit board, and also to provide an electronic device having such a wiring board. <P>SOLUTION: The wiring board 9 has electrode pads 2 which are formed on the top face of the insulation substrate 1 and electrically connected by and mounted with the electronic component 5, and also has inside therein a wiring conductor 3 electrically connected to the electrode pads 2. In the insulation substrate 1, a stepped portion 1a is formed between the side face and the periphery of the bottom face. On the bottom face of the insulation substrate 1 except for the stepped portion 1a, a plurality of connection pads 4 are formed which are electrically connected to the electrode pads 2 via the wiring conductor 3. These connection pads 4 are electrically connected to the circuit wiring 7 of an external electric circuit board 6 mounted with the electronic elements 8, with the electronic elements 8 located in the stepped portion 1a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a wiring board for mounting a semiconductor element such as a semiconductor integrated circuit element or an optical semiconductor element, a vibrator such as a piezoelectric vibrator or a crystal vibrator, and other various electronic components.

Conventionally, for example, a semiconductor substrate such as a semiconductor integrated circuit element or an optical semiconductor element, a vibrator such as a piezoelectric vibrator or a crystal vibrator, and a wiring board for mounting various other electronic components have been made of an aluminum oxide sintered body or the like. An insulating base on which an electronic component is mounted on the upper surface, an electrode pad formed on or around the portion on which the electronic component is mounted on the upper surface of the insulating base, and electrically connected to an electrode of the electronic component; A wiring conductor formed inside the substrate and electrically connected to the electrode pad; and a connection pad formed on the outer peripheral portion of the lower surface of the insulating substrate and electrically connected to the electrode pad via the wiring conductor; It is the composition which consists of.
An electronic component is mounted on the upper surface of the insulating substrate, and the electrodes of the electronic component are electrically connected to corresponding electrode pads via a conductive connecting material such as solder or a bonding wire.
The electronic parts mounted on the mounting part are sealed with a lid or sealing resin, so that arithmetic parts of electronic devices such as PA (power amplifier) modules and FE (front end) modules for mobile phones are used. Thus, an electronic device used as a computing component for a computer is completed.
In this electronic device, the electronic device is mounted on the external electric circuit board by electrically connecting the connection pads to the circuit wiring of the external electric circuit board, and the electrodes of the electronic components are connected to the circuit wiring of the external electric circuit board. And electrically connected.
An external electric circuit board on which an electronic device is mounted is incorporated and used as a main component of an electronic device such as a mobile phone, a portable terminal, a computer, or a general household appliance.

  In addition to the electronic device, various electronic elements such as a so-called surface mount type are mounted and mounted on the external electric circuit board on which the electronic device is mounted. The electronic element in this case is the same as the above-described electronic component, a capacitive element, a resistor (chip resistor), etc., which does not need to be mounted or sealed on the wiring board, a transistor, etc. Functions that control the electrical characteristics (capacitance, DC resistance, impedance, etc.) of the external electric circuit to predetermined characteristic values by using an independently functioning device and forming an electronic circuit with the electronic device. Make.

In recent years, the number of external electric circuit boards on which such electronic devices are mounted has been reduced while reducing the plane area in response to demands for downsizing and higher functionality of electronic devices such as mobile phones in which they are used. There is a need to mount the electronic elements.
JP 2003-007883 A JP 2002-190540 A

  However, in the above-described conventional wiring board, for example, in order to mount a semiconductor integrated circuit element for control, a crystal oscillator for oscillation, and a piezoelectric vibrator on the wiring board and seal with a lid or the like, There is a problem that miniaturization of the external electric circuit board is hindered because the insulating base requires a plane area that is somewhat larger than the plane area of the component.

  The present invention has been completed in view of the above-described problems in the prior art, and an object of the present invention is to provide an electronic component mounted on the upper surface and wiring mounted on an external electric circuit board on which the electronic element is mounted. An object of the present invention is to provide a wiring board and an electronic device that can easily further reduce the size of an external electric circuit board.

  The wiring board of the present invention has an electrode pad on which an electronic component is electrically connected and mounted on an upper surface of an insulating base, and a wiring conductor electrically connected to the electrode pad is formed inside. In the wiring substrate, the insulating base has a stepped portion formed between a side surface and an outer peripheral portion of the lower surface, and is electrically connected to the electrode pad via the wiring conductor at a portion other than the stepped portion on the lower surface. A plurality of connected connection pads are formed, and the plurality of connection pads are electrically connected to the circuit wiring of the external electric circuit board on which the electronic elements are mounted so that the electronic elements are positioned at the stepped portion. It is characterized by being connected to.

  According to another aspect of the present invention, there is provided an electronic device comprising: the wiring board having the above structure; and an electronic component having an electrode electrically connected to the electrode pad and mounted on the upper surface of the insulating base. Is.

  According to the wiring board of the present invention, the insulating base on which the electronic component is mounted on the upper surface has the stepped portion formed between the side surface and the outer peripheral portion of the lower surface, and the wiring conductor is provided on the portion other than the stepped portion on the lower surface. A plurality of connection pads electrically connected to the electrode pads are formed, and the plurality of connection pads are located in the circuit wiring of the external electric circuit board on which the electronic elements are mounted, and the electronic elements are located at the stepped portions. In this way, the stepped portion between the side surface of the insulating base and the outer peripheral portion of the bottom surface, that is, the position where the electronic component mounted on the top surface side of the insulating base overlaps the electronic component in a plan view. An element can be mounted. As a result, the area occupied by the electronic element and the electronic device in the external electric circuit board can be further reduced, and downsizing of the external electric circuit board can be facilitated.

  Further, according to the wiring board of the present invention, since the electronic element is located at the step portion between the side surface of the insulating base and the outer peripheral portion of the lower surface, the electronic element is hidden under the insulating base in a plan view. Compared with the case where it is completely exposed to the outside air and mounted on an external electric circuit board, the influence of dust can be reduced, and the deterioration caused by dust etc. when used for a long period of time is more effective. The long-term reliability of the entire external electric circuit board on which the wiring board is mounted can be further improved.

  In this case, for example, by filling an electrical insulating material such as a resin between the connection pad and the stepped portion between the side surface of the insulating base and the outer peripheral portion of the lower surface, The electrical and mechanical connections between the two, and more effectively preventing the deterioration of the electronic elements, further improving the long-term reliability of the entire external electric circuit board it can.

  The electronic device according to the present invention includes the wiring board having the above-described configuration and an electronic component in which the electrode is electrically connected to the electrode pad and mounted on the upper surface of the insulating base. Further reduction in size is facilitated, and an electronic device having excellent electrical connection reliability between the electronic component and the circuit wiring can be obtained.

  The wiring board of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board according to the present invention.

  In FIG. 1, 1 is an insulating substrate, 1a is a step portion, 2 is an electrode pad, 3 is a wiring conductor, and 4 is a connection pad. The insulating substrate 1, the stepped portion 1a, the electrode pad 2, the wiring conductor 3, and the connection pad 4 basically constitute the wiring substrate 9 of the present invention.

  The insulating substrate 1 is made of an electrically insulating material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon nitride sintered body, a silicon carbide sintered body, or a glass ceramic sintered body. The electronic component 5 is mounted on the upper surface.

  When the insulating base 1 is made of, for example, an aluminum oxide sintered body, it is manufactured as follows. First, an appropriate organic binder and solvent are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide to produce a slurry ceramic slurry, and this ceramic slurry is subjected to a doctor blade method, a calender roll method, etc. A ceramic green sheet (ceramic green sheet) is obtained by forming a sheet by employing the sheet forming technique. Thereafter, the ceramic green sheet is punched and processed into predetermined dimensions and shapes, and is laminated in the predetermined order to form a green ceramic molded body. The green ceramic body is fired at a high temperature of about 1600 ° C. in a reducing atmosphere, whereby the insulating substrate 1 is manufactured.

  On the upper surface of the insulating base 1, an electrode pad 2 on which the electronic component 5 is electrically connected and mounted is formed. The electronic component 5 is a semiconductor element such as a semiconductor integrated circuit element or an optical semiconductor element, a vibrator such as a piezoelectric vibrator or a crystal vibrator, and other various electronic parts.

  A wiring conductor 3 is formed inside the insulating substrate 1. A part of the wiring conductor 3 is led out to a portion where the electronic component 5 on the upper surface of the insulating base 1 is mounted or its periphery, and is electrically connected to the electrode pad 2 at the leading portion. The electrode pad 2 functions as a pad for electrically connecting the electrode of the electronic component 5, and the electrode of the electronic component 5 is electrically connected to the electrode pad 2 through a conductive connecting material such as a bonding wire or solder. By doing so, the electrode of the electronic component 5 and the wiring conductor 3 are electrically connected through the conductive connecting material and the electrode pad 2.

  The connection pad 4 is formed on the lower surface of the insulating base 1 other than the stepped portion 1 a so as to be electrically connected to the wiring conductor 3. The connection pad 4 is connected to the electrode pad 2 via the wiring conductor 3. Electrically connected. By electrically connecting the connection pad 4 to the circuit wiring 7 of the external electric circuit board 6 via solder or the like, the electrode of the electronic component 5 electrically connected to the electrode pad 2 is connected to the external electric circuit board. 6 is electrically connected to the circuit wiring 7.

  The wiring conductor 3 and the connection pad 4 are electrically connected by forming a through conductor inside the insulating base 1 or connecting a side conductor on the side surface in order to connect the wiring conductor 3 and the connection pad 4. Can be performed.

  These wiring conductor 3, electrode pad 2 and connection pad 4 are made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, etc. It is formed by printing a predetermined pattern on the surface of the ceramic green sheet to be an insulating layer by a screen printing method or the like, or printing and filling into a through-hole previously punched and formed in the ceramic green sheet.

  The external electric circuit board 6 in which the connection pads 4 of the wiring board 9 are electrically connected to the circuit wiring is mounted with various electronic elements 8 such as a so-called surface mount type. The electronic element 8 is the same as the electronic component 5 described above, a capacitive element, a resistor (chip resistor), or the like, which does not need to be mounted or sealed on the wiring board 9, or a transistor or the like. Those that function independently are used, and by forming an electronic circuit together with the wiring conductor 3 of the wiring substrate 9 and electronic components mounted on the wiring substrate 9, the electrical characteristics (capacitance of the external electric circuit substrate 6) , DC resistance, impedance, etc.) to a predetermined characteristic value.

  In the wiring board 9 of the present invention, a stepped portion 1 a is formed between the side surface of the insulating base 1 and the outer peripheral portion of the lower surface. An electronic element 8 mounted on the external electric circuit board 6 is located at the stepped portion 1a. With this configuration, the electronic element 8 can be mounted at a position overlapping the electronic component 5 mounted on the upper surface of the insulating substrate 1 in plan view. As a result, the area occupied by the electronic element 8 and the wiring board 9 (electronic device 10) in the external electric circuit board 6 can be further reduced, and further reduction in size of the external electric circuit board 6 can be facilitated. it can.

  In addition, the electronic element 8 located in the level | step-difference part 1a is not restricted to all the electronic elements mounted in the external electric circuit board | substrate 6, and may be a part. Even in such a case, since the total mounting area of the electronic element 8 and the electronic device 10 can be reduced, the external electric circuit board 6 can be effectively downsized. For example, the size of the external electric circuit board 6 used for the mobile phone is about 1 to 3 cm in length on one side, and even if the stepped portion 1a is formed to reduce the size by several mm, The planar area can be reduced to more than 10%.

  The stepped portion 1a is formed on the outer peripheral portion of the ceramic green sheet for the ceramic green sheet to be the insulating base 1 that is the lowest layer when laminated or one to a plurality of layers from the bottom to the top. The center part of the laminated ceramic green sheets is convex by performing punching using a mold with an opening formed or a mold that removes the outer periphery of the ceramic green sheet. Or the like.

  The size of the stepped portion 1a is preferably as large as possible in order to place more electronic elements 8 on the stepped portion 1a to reduce the size of the external electric circuit board 6, but the lower surface of the insulating substrate 1 other than the stepped portion 1a. That is, it is necessary to secure a space for forming the connection pad 4 on the lower surface of the insulating base 1 inside the stepped portion 1a. Therefore, at least the width of the connection pads 4, for example, if the connection pads 4 are circular, the diameter and the adjacent interval between the connection pads 4 are the total length of the connection pads 4 arranged on the outermost periphery. It is necessary to ensure an area in the central portion of the insulating base 1 so as to accommodate a polygon whose side is the length of the side.

  For example, when the connection pads 4 are arranged in a square shape vertically and horizontally, (the width of the connection pads 4 in the vertical direction + the interval between the connection pads 4 in the vertical direction) × (the number of the connection pads 4 in the vertical direction−1). ) × (width of the lateral connection pads 4 + interval between the lateral connection pads 4) × (number of lateral connection pads 4−1) is secured in the central portion of the insulating substrate 1 To do.

When the connection pad 4 is circular, the diameter is preferably 0.2 mm or more in order to sufficiently ensure the reliability of electrical connection with the circuit wiring of the external electric circuit board 6.

  The height and depth of the stepped portion 1a can be appropriately set according to conditions such as the height of the electronic element 8 located in the stepped portion 1a and the routing of the wiring conductor 3 inside the insulating base 1.

  Further, the stepped portion 1a does not need to be formed with the same height and depth over the entire circumference of the outer peripheral portion of the insulating base 1, and is appropriately changed depending on the location in accordance with the number, shape, mounting position, etc. of the electronic elements 8. May be. The insulating base 1 may have a part where the stepped portion 1a is not formed on the outer peripheral portion, but the stepped portion 1a may be formed at the same height and depth on the outer peripheral portion of the insulating base 1 over the entire circumference. It is preferable in terms of securing the mechanical strength of the insulating substrate 1.

  Then, the electronic component 5 is positioned and placed on the upper surface of the insulating base 1, and the electrodes of the electronic component 5 are connected to the electrode pad 2 via a conductive connecting material such as solder or bonding wire, and the electronic component is used as necessary. By sealing 5 with a sealing means (not shown) such as a lid or a sealing resin, the electronic device 10 of the present invention is formed. In this electronic device 10, after the electronic element 8 mounted on the external electric circuit board 6 is positioned at the step portion 1a, the connection pad 4 is electrically and mechanically connected to the corresponding circuit wiring 7 via solder or the like. Thus, the electronic device 10 is mounted on the external electric circuit board 6.

  According to the electronic device 10 of the present invention, the wiring board 9 having the above configuration and the electronic component 5 in which the electrode is electrically connected to the electrode pad 2 and is mounted on the upper surface of the insulating base 1 are provided. Further, it is possible to make the external electric circuit board 6 easier to miniaturize and to make the electronic device 10 excellent in the electrical connection reliability between the electronic component 5 and the circuit wiring 7.

  The external electric circuit board 6 on which the electronic device 10 is mounted is incorporated and used as a main part of an electronic device such as a main part of an electronic device such as a mobile phone, a portable terminal, a computer, or a general household electrical appliance.

  According to the wiring board 9 and the electronic device 10 of the present invention, the electronic element 8 is located in the stepped portion 1a between the side surface of the insulating base 1 and the outer peripheral portion of the lower surface. Compared with the case where it is hidden on the lower side of 1 and mounted on the external electric circuit board 6 in a state of being completely exposed to the outside air, the influence of dust can be reduced, and the dust when used for a long time It is possible to more effectively prevent deterioration due to the above and to improve the long-term reliability of the entire external electric circuit board 6 on which the wiring board 9 is mounted.

  Further, for example, by filling an electrical insulating material (not shown) such as a resin between the connection pad 4 and the stepped portion 1a between the side surface of the insulating base 1 and the outer peripheral portion of the lower surface, the wiring substrate 9 and The electrical and mechanical connection with the external electric circuit board 6 is made stronger, the deterioration of the electronic element 8 is more effectively prevented, and the long-term reliability of the entire external electric circuit board 6 is further improved. The property can be made excellent.

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.

It is sectional drawing which shows an example of embodiment of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 1a ... Step part 2 ... Electrode pad 3 ... Wiring conductor 4 ... Connection pad 5 ... Electronic component 6 ... External electric circuit board 7 ... Circuit wiring 8 ... Electronic element 9 ... Wiring board 10 ... Electronic device

Claims (2)

In the wiring substrate in which an electrode pad to be mounted by electrically connecting an electronic component is formed on the upper surface of the insulating base, and a wiring conductor electrically connected to the electrode pad is formed therein, the insulating substrate The base body has a stepped portion formed between the side surface and the outer peripheral portion of the lower surface, and a plurality of connections electrically connected to the electrode pad via the wiring conductor at a portion other than the stepped portion on the lower surface Pads are formed, and the plurality of connection pads are electrically connected to circuit wiring of an external electric circuit board on which electronic elements are mounted so that the electronic elements are positioned at the stepped portion. A wiring board characterized by. 2. An electronic device comprising: the wiring board according to claim 1; and an electronic component having an electrode electrically connected to the electrode pad and mounted on an upper surface of the insulating base.

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