JP3866128B2 - Wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring board for mounting electronic components such as semiconductor elements and piezoelectric vibrators.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a wiring board for mounting electronic components such as semiconductor elements and piezoelectric vibrators is generally made of a substantially square plate-like ceramic material, and has an insulating base having a recess for mounting and housing the electronic components on the upper surface, and the insulating substrate. A plurality of wiring conductors, one end of which is led out in the recess of the base body and the other end of the side face thereof, a frame-like metal layer formed on the upper surface of the insulating base so as to surround the recess, and the insulation A plurality of connection pads formed on the outer peripheral portion of the lower surface of the base, and a plurality of castellation conductors formed on the side surface of the insulating base and electrically connecting the wiring conductor and each connection pad. In addition to mounting an electronic component on the bottom surface of the recess of the insulating base, each electrode for signal and grounding of the electronic component is bonded to one end of each wiring conductor that is led into the recess of the insulating base. Connected through a conductive connecting member electrically, thereafter, the iron so as to cover the electronic component to the frame-like metal layer of the insulating substrate top surface - nickel - cobalt alloy or an iron - metal made of nickel alloy An electronic device is obtained by sealing the electronic component by bonding the lid body of the metal plate through a brazing material or the like.
[0003]
Such an electronic device is mounted on an external electric circuit board by connecting connection pads formed on the outer peripheral portion of the lower surface of the insulating base to circuit wiring of the external electric circuit board via solder such as tin-lead solder, and at the same time, an electronic component These electrodes are connected to the castellation conductor from one end side of the wiring conductor to the other end, and are also electrically connected to an external electric circuit via the castellation conductor and the connection pad.
[0004]
Among the castellation conductors, at least a grounding electrode of an electronic component is connected (usually about 20 to 50% of all connection pads), a part of which is formed on the upper surface of the insulating base. The metal layer is led out so that the frame-shaped metal layer can be grounded.
[0005]
Each castellation conductor is formed in a direction perpendicular to the side surface of the insulating base, and the castellation conductor connected to the frame-like metal layer is formed from the bottom surface to the top surface on the side surface of the insulating base.
[0006]
[Problems to be solved by the invention]
However, recently, various electronic devices contain lead such as tin-silver-bismuth, tin-silver-copper-bismuth, etc. in place of tin-lead solder which is conventionally used to prevent adverse effects on the environment and human body. The so-called lead-free solder is used to connect to an external electric circuit board, and such a lead-free solder is easier to flow at the time of melting than a conventional tin-lead solder. When mounting on the substrate, the solder crawls up to the frame-like metal layer on the upper surface of the insulating base or the metal lid attached to the frame-like metal layer through the castellation conductor, and as a result, the insulating base The amount of solder interposed between the connection pad and the circuit wiring of the external electric circuit is extremely small, and the electronic device cannot be firmly mounted on the external circuit board. In addition, with the remarkable miniaturization of the wiring board, the frame-shaped metal layer is also formed with a narrow width and close to the outer edge of the insulating base. When the second region turns the frame-shaped metal layer inward at the portion connected to the second region, the width of the frame-shaped metal layer becomes narrow at this connection site, and the frame-shaped metal layer is made of metal. When the lid body is joined via a brazing material or the like, the amount of brazing material interposed between the frame-shaped metal layer and the metallic lid body is insufficient, and the reliability of hermetic sealing of electronic components is reduced. There was also the problem of a drop.
[0007]
The present invention has been devised in view of the above-described drawbacks, and its purpose is to firmly connect the connection pads to the circuit wiring of the external electric circuit board via lead-free solder, and thereby to the external electric circuit board. Another object of the present invention is to provide a wiring board that can be mounted with high reliability and is excellent in airtight sealing of electronic components.
[0008]
[Means for Solving the Problems]
The present invention provides an insulating base having a recess for accommodating an electronic component on the top surface, a frame-shaped metal layer formed on the top surface of the insulating base and surrounding the recess, and one end in the recess of the insulating base, A plurality of wiring conductors whose other ends are led out to the side surface, a plurality of connection pads formed on the outer peripheral portion of the lower surface of the insulating base, and the wiring conductor and the frame shape formed on the side of the insulating base A wiring board comprising a plurality of castellation conductors for connecting the metal layer and the connection pad, wherein the castellation conductor for connecting the frame-shaped metal layer and the connection pad is a first region derived from the connection pad. And a second region derived from the frame-shaped metal layer, and the first region and the second region are displaced in the width direction of the side surface of the insulating base and are formed in the insulating base. Through It is continued, and the insulating substrate has a bulging portion in the area between one end of the wiring conductor adjacent recess wall extends frame-like metal layer on the upper surface of the bulging portion It is characterized by this.
[0009]
According to the wiring board of the present invention, the castellation conductor that electrically connects the frame-shaped metal layer formed on the upper surface of the insulating base and the connection pad formed on the lower surface of the insulating base is led out from the connection pad. Since the first region and the second region derived from the metal layer are formed, and the first region and the second region are shifted in the width direction of the side surface of the insulating base, the connection pad and the circuit wiring of the external electric circuit Even if the lead-free solder is joined using lead-free solder, the lead-free solder does not crawl up to the frame-like metal layer or the metal lid through the castellation conductor. A sufficient amount of solder can be interposed between the circuit wiring of the substrate and the wiring substrate (electronic device) can be bonded to the external electric circuit substrate very firmly.
[0010]
According to the wiring board of the present invention, the insulating base has a bulging portion in the region between the ends of the adjacent wiring conductors on the inner wall surface of the recess, and the frame-shaped metal layer extends on the upper surface of the bulging portion. As the wiring board is downsized, the width of the frame-like metal layer becomes narrower and is formed to the vicinity of the outer edge of the insulating base and is connected to the second region of the castellation conductor. in part, even if the second region is now gouging the frame-like metal layer on the inside, it is possible to ensure the width of the frame-like metal layer, brazing a metal lid to a frame-like metal layer When bonded via a material, etc., a sufficient amount of brazing material can be interposed between the frame-shaped metal layer and the metal lid to ensure the reliability of hermetic sealing of electronic components Can do.
[0011]
Further, according to the wiring board of the present invention, since the bulging portion of the insulating base is formed in a region between one ends of the adjacent wiring conductors, an extra space is secured in the recess to provide the bulging portion. There is no need to do this, and the wiring board can be easily downsized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1A to 1C show an embodiment in which the wiring board of the present invention is applied to a semiconductor element housing package for housing semiconductor elements, where 1 is an insulating substrate, 2 is a wiring conductor, Frame-shaped metal layer (hereinafter referred to as “frame-shaped metal layer”) 4 is a connection pad, and 5 is a castellation conductor. The insulating substrate 1, the wiring conductor 2, the frame-shaped metal layer 3, the connection pad 4, and the castellation conductor 5 form a wiring substrate 7 for mounting the semiconductor element 6.
[0013]
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 glass ceramic sintered body, and the like, and a recess for mounting and housing the semiconductor element 6 on the upper surface thereof. 1a, and the semiconductor element 6 is bonded and fixed to the bottom surface of the recess 1a through an adhesive such as glass, resin, or brazing material.
[0014]
When the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, a suitable 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 form a mud-like shape. Next, the ceramic slurry is formed into a sheet shape by a sheet forming technique such as a conventionally known doctor blade method or calendar roll method to obtain a ceramic green sheet (ceramic raw sheet) having a predetermined shape. A plurality of ceramic green sheets are laminated and fired at a temperature of about 1600 ° C. in a reducing atmosphere.
[0015]
The insulating base 1 has a plurality of wiring conductors 2 formed such that one end thereof is led out into the recess 1a in which the semiconductor element 6 on the upper surface is mounted, and the other end thereof is led out to the side surface. 2 acts as a conductive path for connecting each electrode for signal and ground of the semiconductor element 6 to the connection pad 4, and for one end exposed in the recess 1 a, the signal for the semiconductor element 6, for grounding, etc. The electrodes are electrically connected via bonding wires 8.
[0016]
The wiring conductor 2 is made of a metal powder such as tungsten, molybdenum, manganese, copper, silver, gold, palladium, etc., and a metal paste obtained by adding and mixing an appropriate organic binder or solvent to the metal powder such as tungsten is used as the insulating substrate 1. The ceramic green sheet is preliminarily printed in a predetermined pattern by a well-known screen printing method so that one end is formed in the recess 1a of the insulating substrate 1 and the other end is led out to the side surface. The
[0017]
The insulating substrate 1 also in its upper surface, a frame-like metal layer 3 so as to surround the recess 1a of the semiconductor element 6 is mounted are deposited, metallic lid 9 the frame-like metal layer 3 to be described later Acts as a base metal layer for attaching to the insulating substrate 1, and is made of metal powder such as tungsten, molybdenum, manganese, copper, silver, gold, palladium.
[0018]
A metal lid 9 is brazed and attached to the frame-like metal layer 3 via a brazing material, whereby the semiconductor element 6 mounted and accommodated in the recess of the insulating base 1 is hermetically sealed from the atmosphere. The Rukoto.
[0019]
The frame-shaped metal layer 3 is formed on the upper surface of the insulating base 1 so as to surround the recess 1a by the same method as that for the wiring conductor 2 described above.
[0020]
Further, a plurality of connection pads 4 are formed on the outer peripheral portion of the lower surface of the insulating base 1, and the connection pads 4 are connected to the circuit wiring of the external electric circuit board via lead-free solder. Each electrode for grounding and grounding is electrically connected to an external electric circuit.
[0021]
The connection pad 4 is made of a metal powder such as tungsten, molybdenum, manganese, copper, silver, gold, or palladium, and is formed in a predetermined shape on the outer periphery of the lower surface of the insulating substrate 1 by the same method as that for the wiring conductor 2 described above. .
[0022]
Further, the insulating base 1 is coated with a plurality of castoration conductors 5 (a conductor formed in the side of the insulating base 1 having a semicircular cross-sectional groove formed on the side), The castellation conductor 5 serves to electrically connect the wiring conductor 2 and the connection pad 4.
[0023]
The castellation conductor 5 is made of a metal powder such as tungsten, molybdenum, manganese, copper, silver, gold, palladium, etc., and a semicircular recess is formed on the side surface of the ceramic green sheet serving as the insulating substrate 1 by a punching method. A metal paste obtained by adding and mixing a suitable organic binder or solvent to a metal powder such as tungsten in the recess is preliminarily printed in a predetermined pattern by a well-known screen printing method, and then predetermined on the side surface of the insulating substrate 1. It is formed into a shape.
[0024]
A part of the castellation conductor 5 connected to the wiring conductor 2 that is electrically connected to the grounding electrode of the semiconductor element 6 is led out to the frame-like metal layer 3 on the upper surface of the insulating base 1. The metal layer 3 is grounded.
[0025]
The wiring conductor 2, the frame-like metal layer 3 , the connection pad 4 and the castoration conductor 5 have corrosion resistance such as nickel and gold, bonding property of the bonding wire 8, solder wettability, etc. on the exposed surface. If a plating layer made of a good metal is applied, the oxidative corrosion of the wiring conductor 2 and the frame-shaped metal layer 3 can be effectively prevented, and the metal lid 9 is attached to the frame-shaped metal layer 3. The connection of the contact and connection pads 4 to the external electric circuit board is ensured and strong. Therefore, the wiring conductor 2, the frame-shaped metal layer 3, the connection pad 4, and the castoration conductor 5 are made of a metal having good corrosion resistance such as nickel and gold, bonding properties, solder wettability, etc. on the exposed surface. It is preferable to deposit by a plating method. In particular, it is preferable to sequentially deposit, for example, a nickel plating layer having a thickness of 1 to 10 μm and a gold plating layer having a thickness of 0.05 to 3 μm.
[0026]
In this case, the thickness of the gold plating layer may be different depending on the part to be deposited, the crystal orientation of the gold plating layer, etc. For example, the crystal orientation in the X-ray diffraction of the gold plating layer is as much as possible to the (111) plane. In addition, the entire region including the region to which the bonding wire 8 is connected may be about 0.3 to 1 μm, and only the region for soldering should be as thin as about 0.3 μm or less. -Generation | occurrence | production of the gold | metal brittle intermetallic compound may be suppressed, and you may make it improve the reliability of soldering.
[0027]
Thus, according to the wiring board 7 of the present invention, the semiconductor element 6 is mounted and accommodated in the recess 1a on the upper surface of the insulating base 1, and the signal and ground electrodes of the semiconductor element 6 are led out into the recess 1a of the wiring conductor 2. After being connected to one end via a bonding wire 8, a metal lid 9 made of iron-nickel-cobalt alloy, iron-nickel alloy or the like is attached to the frame-like metal layer 3 on the upper surface of the insulating substrate 1 with a brazing material or the like. The electronic device (semiconductor device) as a product is completed by sealing the semiconductor element 6 with the metal lid 9 in an airtight manner.
[0028]
This semiconductor device is mounted on the external electric circuit board by bonding the connection pads 4 on the outer periphery of the lower surface of the insulating base 1 to the circuit wiring of the external electric circuit board via lead-free solder, and at the same time, the signal of the semiconductor element 6 The grounding and grounding electrodes are electrically connected to the circuit wiring of the external electric circuit board.
[0029]
In the wiring board 7 of the present invention, the caster conductor 5a connecting the frame-like metal layer 3 and the connection pad 4 out of the caster conductor 5 is led out from the connection pad 4 as shown in FIG. And the second region 5c led out from the frame-like metal layer 3 , and the first region 5b and the second region 5c are shifted in the width direction of the side surface of the insulating substrate 1 and the internal wiring is formed inside the insulating substrate 1. It is important to be electrically connected through the layer 10.
[0030]
The castellation conductor 5a connecting the frame-shaped metal layer 3 and the connection pad 4 is divided into a first region 5b derived from the connection pad 4 and a second region 5c derived from the frame-shaped metal layer 3, If the position is shifted in the width direction of the side surface of the insulating base 1, even if the connection pad 4 and the circuit wiring of the external electric circuit are joined using lead-free solder, the lead-free solder is transmitted through the castellation conductor to form a frame shape. As a result, a sufficient amount of solder can be interposed between the connection pad 4 and the circuit wiring of the external electric circuit board. Electronic device) can be bonded to the external electric circuit board very firmly.
[0031]
The dividing position of the first region 5b and the second region 5c of the castellation conductor 5a connecting the frame-shaped metal layer 3 and the connection pad 4 is the type of solder used, the thickness of the insulating substrate 1, What is necessary is just to determine suitably according to the design convenience etc. of the wiring conductor 2, for example, the castellation conductor 5a is semicircle shape with a diameter of 0.3 mm-0.7 mm, and uses a tin-silver type solder as a solder. In some cases, the length of the first region 5b may be in the range of 0.3 mm to 1 mm.
[0032]
Further, in the wiring board 7 of the present invention, as shown in FIGS. 2 and 3, the bulging portion 11 is provided in the region between the ends of the adjacent wiring conductors 2 on the inner wall surface of the recess 1a of the insulating base 1, and It is important to extend the frame-like metal layer 3 on the upper surface of the protruding portion 11.
[0033]
If the bulging portion 11 is provided and the frame-shaped metal layer 3 is extended on the upper surface in this way, the width of the frame-shaped metal layer 3 becomes narrower and the insulating substrate 1 of the insulating substrate 1 is reduced as the wiring board 7 is downsized. Even if the second region 5c comes to wrap the frame-shaped metal layer 3 inwardly at the portion connected to the second region 5c of the castellation conductor 5a, the frame-like metal layer 3 is formed in the vicinity of the outer edge. The width of the metal layer 3 can be secured, and when the metal lid body 9 is joined to the frame-shaped metal layer 3 via a brazing material or the like, the frame-shaped metal layer 3 and the metal lid body 9 A sufficient amount of brazing material can be interposed between them, and the reliability of hermetic sealing of the semiconductor element 6 can be ensured.
[0034]
When the bulging portion 11 is formed so as to overlap with a portion where one end of the wiring conductor 2 is led out on the inner wall surface of the recess 1 a of the insulating base 1, the bonding wire 8 is connected to one end of the wiring conductor 2. It is necessary to form the wiring conductor 2 by extending it into the recess 1a as much as the bulging portion 11, and the wiring board 7 is prevented from being miniaturized. Therefore, the bulging portion 11 needs to be provided in a region between one end of the adjacent wiring conductor 2 on the inner wall surface of the recess 1 a of the insulating base 1.
[0035]
Further, the bulging portion 11 needs to be formed in a portion where the second region 5c of the castellation conductor 5a is connected to the frame-shaped metal layer 3 (a portion where the width of the frame-shaped metal layer 3 is narrow). Needs to position the second region 5c of the castellation conductor 5a on the side surface portion of the insulating base 1 facing the region between the ends of the adjacent wiring conductors 2.
[0036]
Such a bulging portion 11 is formed by punching a ceramic green sheet on which the frame-shaped metal layer 3 is deposited on the upper surface so that a portion that becomes the bulging portion 11 is formed in part. Can be formed.
[0037]
Incidentally, the bulging portion 11, the previously formed so as to substantially the same shape as the second region 5c by scooped frame-like metal layer 3 in the form of castellations conductors 5a, the frame-like metal layer 3 The width can be made substantially uniform over the entire circumference, and the reliability of hermetic sealing can be more reliably ensured. Therefore, it is preferable that the protruding portion 3a is formed so as to have substantially the same shape as the shape of the frame-shaped metal layer 3 scraped by the second region 5c of the castellation conductor 5a.
[0038]
In this case, when the maximum bulging dimension of the bulging portion 11 exceeds 0.5 mm, the bulging distance with respect to the inside of the concave portion 1a becomes large, and there is a possibility that it is difficult to reduce the size of the wiring board 7. Therefore, it is preferable that the bulging portion 11 has a maximum bulging dimension of 0.5 mm or less.
[0039]
Further, as shown in FIG. 4, the first region 5b led out from the connection pad 4 of the castellation conductor 5a has a projection 12 projecting inward so that the connection pad 4 can be connected to the external electric circuit board. When joining to circuit wiring via solder, the protrusion 12 is joined so as to bite into the solder, thereby further strengthening the joining strength. Therefore, the first region 5b led out from the connection pad 4 of the castellation conductor 5a is preferably formed with a protruding portion 12 protruding inward as shown in FIG.
[0040]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiments, the wiring board of the present invention is a semiconductor. Although the present invention is applied to a package for housing a semiconductor element that houses elements, it may be applied to other uses such as a hybrid integrated circuit board.
[0041]
In addition, in the accompanying drawings of the above-described embodiments, an example in which the bulging portion is provided near the wiring conductor is shown. However, depending on the arrangement of the wiring conductor and the castellation conductor, the bulging portion is located at the center of the adjacent wiring conductor. You may provide in a part, and you may provide two or more bulging parts in between one adjacent.
[0042]
【The invention's effect】
According to the wiring board of the present invention, the castellation conductor that electrically connects the frame-shaped metal layer formed on the upper surface of the insulating base and the connection pad formed on the lower surface of the insulating base is led out from the connection pad. 1 region and a second region derived from the metal layer, and the first region and the second region are shifted in the width direction of the side surface of the insulating base. Even if they are joined using lead-free solder, lead-free solder does not crawl up to the frame-like metal layer or metal lid through the castellation conductor. A sufficient amount of solder can be interposed between the circuit wiring and the wiring board (electronic device) can be bonded to the external electric circuit board very firmly.
[0043]
According to the wiring board of the present invention, the insulating base has a bulging portion in the region between the ends of the adjacent wiring conductors on the inner wall surface of the recess, and the frame-like metal layer extends on the upper surface of the bulging portion. Therefore, as the wiring board is reduced in size, the width of the frame-like metal layer becomes narrower and is formed even near the outer edge of the insulating base, and at the portion connected to the second region of the castellation conductor Even if the second region turns the frame-shaped metal layer inside, the width of the frame-shaped metal layer can be secured, and a metal lid is attached to the frame-shaped metal layer via a brazing material or the like. When bonded, a sufficient amount of brazing material can be interposed between the frame-shaped metal layer and the metal lid, and the reliability of hermetic sealing of the electronic component can be ensured.
[0044]
Further, according to the wiring board of the present invention, since the bulging portion of the insulating base is formed in a region between one ends of the adjacent wiring conductors, an extra space is secured in the recess to provide the bulging portion. There is no need to do this, and the wiring board can be easily downsized.
[Brief description of the drawings]
1A, 1B and 1C are a side view, a plan view and a bottom view showing an embodiment of a wiring board according to the present invention.
FIG. 2 is an enlarged perspective view of a main part of a wiring board according to the present invention.
FIG. 3 is an enlarged plan view of a main part of a wiring board according to the present invention.
FIG. 4 is an enlarged view of a main part of another embodiment of the wiring board of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 1a ... Recess 2 ... Wiring conductor 3 ... Frame-shaped metal layer 4 ... Connection pad 5 ... Castoration conductor 5a... Castoration conductor 5b connecting the connection pad and the frame-like metal layer... First region 5c... Second region 6.・ Wiring board 8... Bonding wire 9... Lid 10... Internal wiring layer 11.

Claims (1)

An insulating base having a recess for accommodating an electronic component on the upper surface, a frame-shaped metal layer formed on the upper surface of the insulating base and surrounding the recess, one end in the recess of the insulating base, and the other end on the side A plurality of wiring conductors, a plurality of connection pads formed on the outer periphery of the lower surface of the insulating base, the wiring conductor and a frame-shaped metal layer formed on a side surface of the insulating base; A wiring board comprising a plurality of castellation conductors for connecting a connection pad, wherein the castellation conductor for connecting the frame-shaped metal layer and the connection pad is a first region derived from the connection pad; The first region and the second region are displaced in the width direction of the side surface of the insulating base and connected via an internal wiring layer formed inside the insulating base. Been Ri, and the insulating substrate has a bulging portion in the area between one end of the wiring conductor adjacent recess wall, characterized in that the frame-like metal layer on the upper surface of the bulging portion is extended Wiring board.

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