JP4753539B2 - Electronic component mounting substrate and electronic device using the same - Google Patents

Description

  The present invention relates to a small electronic component mounting board used in an electronic component storage package for accommodating an electronic component therein, and an electronic apparatus using the same.

  2. Description of the Related Art Conventionally, a small electronic component mounting substrate used for an electronic component storage package for storing electronic components such as semiconductor elements and piezoelectric vibrators is an aluminum oxide as shown in FIGS. 2 (a) and 2 (b). It is made of a ceramic material such as a sintered body, an aluminum nitride sintered body, a mullite sintered body, and a glass-ceramic, and has a rectangular mounting portion 16 for mounting electronic components on the main surface such as the upper surface. Insulating base 11, insulating frame 20 formed so as to surround mounting portion 16, electrode pad 12 formed at the corner of mounting portion 16, and rectangular frame shape formed on the upper surface of insulating frame 20. And a metallized layer 14.

  A square frame-shaped metal frame 15 is bonded to the square frame-shaped metallization layer 14 via a brazing material such as silver brazing as necessary.

  In addition, the electrode pad 12 is usually led out to the lower surface or side surface of the insulating base 11 via a wiring conductor 17 formed inside the insulating base 11.

Then, the electronic component 19 is accommodated in a recessed portion formed by the insulating base 11 and the insulating frame 20, and mounted on the mounting portion 16, and the electrodes of the electronic component 19 are electrode pads at the corners of the mounting portion 16. 12 is electrically connected to the insulating base 11 and the insulating frame by bonding a metal lid 18 to the upper surface of the metal frame 15 by a seam weld method or the like. An electronic component 19 is hermetically sealed inside a container composed of a body 20, a metal frame 15 for sealing, and a lid 18, thereby forming an electronic device as a product.
JP-A-9-246415

  In recent years, such an electronic component mounting board and an electronic device using the same have been required to be reduced in size and thickness, and in response to this, as shown in FIGS. Insulating substrate 11 having a rectangular mounting portion 16 for mounting electronic component 19 on the surface, electrode pads 12 formed at the corners of mounting portion 16, and mounting portion 16 on the main surface of insulating substrate 11 A thin electronic component mounting substrate having a structure including a metallization layer 14 having a rectangular frame shape formed so as to surround the substrate has been proposed.

  Then, the electronic component 19 is mounted on the upper surface of the mounting portion 16, and the electrode of the electronic component 19 is electrically connected to the electrode pad 12 via a conductive adhesive or the like. The electronic device 19 is hermetically sealed by joining the lid 18 directly or through a metal frame 15 with a joining means such as a seam welding method, a direct seam method, or a brazing method, thereby completing an electronic device.

  According to such a structure, it is not necessary to separately attach an insulating frame to the upper surface of the insulating base 11, the mounting portion 16 on which the electronic component 19 is mounted, the electrode pad 12 to which the electrode of the electronic component 19 is connected, The square frame-like metallization layer 14 that hermetically seals the electronic component 19 is formed on the same surface, so that the electronic component mounting substrate and the electronic device can be thinned.

  However, in the electronic component storage package and the electronic device configured as described above, the thickness can be reduced. However, due to the downsizing of the electronic device, the electrode pad 12 formed at the corner of the mounting portion 16 and the metallization in the form of a square frame. Since the distance from the layer 14 is narrow, when the electronic component 19 is connected to the electrode pad 12 via a conductive adhesive or the like, the lid is attached to the metallized layer 14 (or the metal frame 15) having a square frame shape. When the body 18 is joined, an electrical short (short) occurs between the electrode pad 12 and the square frame metallization layer 14 due to the flow of a conductive adhesive, brazing material, metal material used for welding, etc. It has a problem that it is likely to occur.

  The present invention has been devised in view of such problems, and its object is to make it possible to reduce the size and thickness, and to electrically short-circuit between the electrode pad and the rectangular metallization layer. It is an object of the present invention to provide a highly reliable electronic component mounting substrate and electronic device that do not induce such troubles.

An electronic component mounting board according to the present invention includes an insulating substrate having a rectangular mounting portion for mounting an electronic component on a main surface, electrode pads formed at corners of the mounting portion, and a main portion of the insulating substrate. The electrode pad has a rectangular metallization layer formed so as to surround the mounting portion on the surface, and the electrode pad has two sides chamfered at the corners between the two sides of the square along the metallization layer the shape, the portions excluding the corners of the rectangular frame-shaped metallized layer at a site between the electrode pad and the metallization layer of the main surface, grooves corresponding to the two sides are formed as characterized by Tei Rukoto It is.

  Also, the electronic component mounting board of the present invention is preferably characterized in that a plurality of the grooves are formed and one opening shape thereof is different from the other opening shape.

  In the electronic component mounting board according to the present invention, preferably, the groove has an inner dimension that gradually increases from the lower end to the upper end.

The electronic device according to the present invention includes an electronic component mounting board according to the present invention, an electronic component mounted on the mounting portion and having an electrode electrically connected to the electrode pad, and a lid attached to the metallization layer. And a body.

  According to the electronic component mounting substrate of the present invention, since the groove is formed in the portion between the electrode pad on the main surface and the square frame-shaped metallization layer, when connecting the electronic component to the electrode pad, the square is formed. When joining the lid to the frame-like metallized layer, even if excess conductive adhesive, brazing material, or metal material used for welding flows out, the electrode pad and the metallized layer are separated by storing them in the groove. The occurrence of an electrical short can be effectively prevented.

In addition, this groove is formed in a portion between the electrode pad and the metallized layer , excluding the corner of the square frame-shaped metallized layer , corresponding to the two chamfered sides of the electrode pad. Further, the strength of the corner portion of the insulating base where the thermal stress at the time of joining the lid acts most can be maintained, and the insulating base can be effectively prevented from being distorted. As a result, it is possible to effectively prevent mechanical breakdown such as cracks (so-called thermal cracks) caused by thermal shock from occurring in the insulating substrate, and the reliability of hermetic sealing of electronic parts is extremely excellent. Can be. Further, since the corner of the electrode pad on the corner side of the metallized layer is chamfered, the distance between the corner of the metallized layer having a square frame shape and the electrode pad can be increased. An electrical short circuit with the layer can be effectively prevented.

  Further, according to the electronic component mounting substrate of the present invention, preferably, the plurality of grooves are formed and one of the opening shapes is different from the other opening shape. Even if it becomes difficult to secure a place on the insulating substrate to form an alignment mark for confirming the directionality after mounting an electronic component, this groove having a different opening shape functions as an alignment mark. By confirming, the directionality of the insulating substrate can be easily confirmed.

  Further, according to the electronic component mounting substrate of the present invention, preferably, the groove has a gradually increasing inner dimension from the lower end to the upper end, so that when the electronic component is connected to the electrode pad or a rectangular frame shape When joining the lid to the metallized layer, even if excess conductive adhesive, brazing material, or metal material used for welding flows out, these can be more effectively guided and stored in the groove. Thus, the occurrence of an electrical short between the electrode pad and the metallized layer can be more effectively prevented.

According to the electronic device of the present invention, the electronic component mounting board of the present invention, the electronic component mounted on the mounting portion and having the electrode electrically connected to the electrode pad, and the lid attached to the metallized layer An electronic device that effectively prevents an electrical short circuit between the electrode pad and the rectangular frame metallization layer and is excellent in the reliability of hermetic sealing of electronic components. Can be provided.

  Next, an electronic component mounting board and an electronic device according to 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 an electronic component mounting board and an electronic device according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA ′ of FIG. FIG. In the figure, 1 is an insulating substrate, 2 is an electrode pad for connecting electronic components, 3 is a groove, 4 is a metallized layer in the form of a square frame, and 5 is a metal frame. The insulating substrate 1, electrode pad 2, groove 3, and rectangular frame-shaped metallization layer 4 constitute the electronic component mounting substrate of the present invention.

  The insulating substrate 1 is made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass-ceramic, and has a side length of about 2 to 20 mm and a thickness of 0.5 to 0.5, for example. It is a square shape of about 3 mm. The insulating substrate 1 may be a single layer or a laminate of two or more layers.

  A rectangular mounting portion 6 for mounting the electronic component 9 is formed on the main surface of the insulating substrate 1 (the upper surface in the example of FIG. 1A).

  If such an insulating substrate 1 is made of an aluminum oxide sintered body, an appropriate organic binder, solvent, plasticizer, etc. are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. As a result, a plurality of ceramic green sheets are obtained by making a sheet shape by a sheet forming method such as a doctor blade method, and then appropriately punching the ceramic green sheets. It is manufactured by laminating up and down and firing the laminate at a high temperature.

  Electrode pads 2 are formed at the corners of the mounting portion 6 of the insulating base 1. The electrode pad 2 functions as a pad for connecting the electrode of the electronic component 9 mounted on the mounting portion 6. The electronic component 9 is, for example, a piezoelectric vibrator, a surface acoustic wave element, or the like. Usually, the outer shape is a square shape, and electrodes are formed at the corners thereof, and the connection of such electrodes is easy and reliable. The electrode pad 2 is formed at the corner of the mounting portion 6 so that it can be performed.

  The electrodes of the electronic component 9 and the electrode pads 2 are connected by electrical connection means using a conductive adhesive such as solder or conductive resin.

  The electrode pad 2 is led to the outer surface of the insulating substrate 1 (the lower surface in the example of FIG. 1B) via, for example, a wiring conductor 7 formed inside or on the surface of the insulating substrate 1. The wiring conductor 7 functions as a conductive path for electrically connecting each electrode of the electronic component 9 mounted on the mounting portion 6 to an external electric circuit, and the wiring conductor 7 is led out to the outer surface of the insulating base 1. By connecting the portion to an external electric circuit via solder or the like, the electrode of the electronic component 9 is electrically connected to the external electric circuit via the electrode pad 2 and the wiring conductor 7.

  The exposed surfaces of the electrode pad 2 and the wiring conductor 7 prevent oxidative corrosion of the electrode pad 2 and the wiring conductor 7, connect the electrode pad 2 to each electrode of the electronic component 9, and connect the wiring conductor 7 to the outside. In order to strengthen the connection with the electric circuit board, normally, a nickel plating layer with a thickness of about 1 to 10 μm and a gold plating layer with a thickness of about 0.1 to 3 μm are preferably sequentially deposited. .

  Further, on the main surface (upper surface) of the insulating substrate 1, a rectangular frame-shaped metallization layer 4 made of metal powder metallization such as tungsten, molybdenum, copper, or silver is formed so as to surround the mounting portion 6. The metallized layer 4 has a thickness of about 10 to 30 μm and a width of each side of about 0.2 to 0.5 mm, and is a base metal for joining the lid 8 or the metal frame 5 to the insulating substrate 1. Function as.

  As shown in FIG. 1, the metallized layer 4 may be brazed with a metal frame 5 for sealing via a brazing material such as silver brazing. When the metal frame 5 is brazed on the surface of the metallized layer 4, for example, a nickel plating layer having a thickness of about 0.5 to 5 μm is brazed on the surface of the metallized layer 4 in order to improve the wettability with the brazing material. It may be pre-deposited before.

  The metal frame 5 is made of a metal such as an iron-nickel alloy or an iron-nickel-cobalt alloy, and functions as a base metal member for welding the lid 8 to the insulating base 1. The metal frame 5 has an inner circumference that is the same size as the outer dimension of the mounting portion 6, has a thickness of about 0.1 to 0.5 mm, and a width of each side of about 0.15 to 0.45 mm.

  As a method of joining the metal frame 5 to the metallized layer 4, a silver brazing having a thickness of 20 to 50 μm is previously applied to the lower surface of the metal frame 5, and the lower surface to which this silver brazing is applied is applied to the metallized layer. By placing on 4 and heating by seam welding, electron beam or the like, the metallized layer 4 can be easily brazed with good airtightness.

  It is to be noted that the metal frame 5 for sealing, the brazing material for bonding the metal frame 5 and the metallized layer 4, and the surface of the exposed square frame-shaped metallized layer 4 are effectively prevented from being oxidized and corroded. In addition, in order to facilitate welding of the metal frame 5 for sealing and the lid 8, a nickel plating layer with a thickness of about 1 to 10 μm and a gold plating layer with a thickness of about 0.3 to 3 μm are usually used. Are preferably deposited sequentially.

  Then, after mounting the electronic component 9 on the mounting portion 6 of the insulating base 1 and connecting the electrode of the electronic component 9 to the electrode pad 2 via a conductive adhesive or the like, the metallized layer 4 or the metal frame 5 is formed on the upper surface. By joining the lid 8 by a welding method such as a seam welding method or an electron beam method, a brazing method, or the like, an electronic component 9 is placed inside a container composed of the lid 8, the metal frame 5, and the insulating base 1. It is hermetically sealed and completed as an electronic device.

  The lid 8 is made of metal, ceramics, or resin, and is attached to the metallized layer 4 or the metal frame 5 by a brazing method, a welding method, or the like. When the lid 8 is made of ceramics or resin, in order to be able to be joined to the metallized layer 4 or the metal frame 5 by a brazing method or a welding method, metallization, plating, metal It is preferable to form a metal conductor by embedding or the like.

  Further, the shape of the lid body 8 is a square flat plate shape or a quadrangular shape having a recess on the lower surface, and when the lid body 8 is directly joined to the metallized layer 4, a cavity for accommodating the electronic component 9 is formed. A rectangular shape having a recess on the lower surface is used.

  In the electronic component mounting substrate and the electronic device using the same according to the present invention, the corners of the metallized layer 4 are formed at portions between the electrode pads 2 on the main surface (upper surface) of the insulating substrate 1 and the metallized layer 4 having a rectangular frame shape. A groove 3 is formed in a portion excluding the portion. As a result, when the electronic component 9 is connected to the electrode pad 2 or when the lid 8 is joined to the rectangular frame-like metallized layer 4, excess conductive adhesive, brazing material, and metal material used for welding flow out. Even so, the accumulation of these in the groove 3 can effectively prevent the occurrence of an electrical short circuit between the electrode pad 2 and the metallized layer 4.

  Further, since the groove 3 is formed in a portion excluding the corner portion of the square frame-shaped metallized layer 4, the corner portion of the insulating base body 1 where the thermal stress at the time of joining the lid body 8 acts most greatly. The strength can be maintained, and the distortion of the insulating substrate 1 can be effectively suppressed. As a result, it is possible to effectively prevent mechanical breakdown such as cracks caused by thermal shock from occurring in the insulating substrate 1, and to make the airtight sealing reliability of the electronic component 9 very excellent. be able to.

  Further, as shown in FIG. 4A, it is preferable that a plurality of grooves 3 are formed and one of the opening shapes is different from the other opening shapes. The shape of the groove 3 ′ formed differently from the other opening shapes is such that, for example, a corner of the rectangular frame-like metallization layer 4 of the insulating substrate 1 is avoided and the distance between the electrode pad 2 and the metallization layer 4 is avoided. In order not to become too narrow, the shape may be longer than the other grooves 3. By forming the groove 3 ′ in this way, the size of the insulating base 1 is further reduced, and a place for forming an alignment mark for confirming the directionality after mounting the electronic component 9 can be secured in the insulating base 1. Even if it becomes difficult, the directionality of the insulating substrate 1 can be easily confirmed by making the groove 3 ′ having a different opening shape function as an alignment mark and confirming its direction.

  Further, when the opening shape of one of the grooves 3 (groove 3 ′) is different from the other, the length is not limited as described above, but the insulating substrate 1 is viewed from the main surface side. If the grooves having different opening shapes can be easily and clearly identified visually, the corners of the metallized layer 4 are removed at the site between the electrode pad 2 and the metallized layer 4 on the main surface. Various shapes can be used as long as they satisfy the requirement of a region.

  For example, the width of one groove 3 ′ is different from the width of another groove 3, and the outer edge shape of one groove 3 ′ is different from the outer edge shape of another groove 3. Is made concave or convex in the plane direction, and the angle formed by the extension line extending the groove 3 and the outer side of the insulating base 1 is made different between one groove 3 ′ and the other groove 3. Can do.

  When the outer side shape of one groove 3 ′ is different from the outer side shape of the other groove 3, the outer side of one groove 3 ′ has an arc shape, a waveform, a bent linear shape, etc. The outer side is linear, the outer side of one groove 3 'is a shape such as a parallelogram, etc., such that the corner is a square that does not form a right angle, and the other grooves 3 are rectangular. be able to.

  In addition, when a part of one groove 3 ′ is concave or convex in the planar direction, the shape of the concave or convex portion is, for example, an easily distinguishable shape such as an arc shape, an elliptical arc shape, a square shape, or a triangular shape. . Note that an electrical short circuit occurs between the electrode pad 2 and the extra metal material that the convex portion contacts the electrode pad 2 and accumulates in the groove 3 ′, or the concave portion excessively narrows the width of the groove 3 ′. The size is adjusted so that the metal material does not easily enter the groove 3 '.

  In the electronic component mounting substrate of the present invention, it is preferable that the groove 3 has a gradually increasing inner dimension from the lower end to the upper end, as shown in FIG.

  As a result, when the electronic component 9 is connected to the electrode pad 2 or when the lid 8 is joined to the rectangular frame-like metallized layer 4, excess conductive adhesive, brazing material, and metal material used for welding flow out. Even in such a case, these can be more effectively guided and accumulated in the groove 3, and the occurrence of an electrical short circuit between the electrode pad 2 and the metallized layer 4 can be more effectively prevented.

  When the inner dimension of the groove 3 is gradually increased from the lower end to the upper end of the groove 3, the angle formed between the side surface of the groove 3 and the main surface of the insulating base 1 is in the range of 95 degrees to 110 degrees. It is preferable. If the angle exceeds 110 degrees, the opening area of the groove 3 tends to increase, so that the groove 3 is in contact with the electrode pad 2 and an electrical short circuit is likely to occur between the electrode pad 2 and the metal material accumulated in the groove 3. Become.

Note that the corner portion of the electrode pad 2 of the corner side of the metallization layer 4 chamfered as shown in FIG. 1 Contact Ku. Thereby, the distance between the corner | angular part of the rectangular frame-shaped metallization layer 4 and the electrode pad 2 can be enlarged, and the electrical short circuit with the electrode pad 2 and the metallization layer 4 can be prevented effectively.

  The distance between the electrode pad 2 and the square frame-like metallization layer 4 is usually about 0.2 to 0.4 mm, and the width of the groove 3 provided between the square frame-like metallization layer 4 and the electrode pad 2 is 0.1 mm or more. Is desirable. Further, it is desirable that the depth of the groove 3 is deeper than the width direction of the groove 3.

  The groove 3 is formed by subjecting the main surface of the insulating substrate 1 to cutting or laser processing. Further, when the insulating base 1 is formed of a laminate of two or more insulating layers, a through-hole serving as the groove 3 is formed in the insulating layer on the mounting portion 6 side, and a plurality of insulating layers are stacked to form the groove 3. May be formed. For example, the thickness of each insulating layer constituting the normal insulating substrate 1 after firing is 0.1 to 0.5 mm, and through holes are formed in the uppermost insulating layer constituting the insulating substrate 1 or in the uppermost layer and its lower layer. By stacking a plurality of insulating layers, the groove 3 having a depth of 0.1 to 0.5 mm can be formed.

  In addition, this invention is not limited to the example of the above-mentioned embodiment, A various deformation | transformation is possible. For example, the insulating substrate 1 may be formed by laminating three or more ceramic layers.

(A) is a top view which shows an example of embodiment of the electronic component mounting substrate of this invention, (b) is sectional drawing in the A-A 'line of the electronic component mounting substrate of (a). (A) is a top view of the conventional electronic component mounting substrate, and (b) is a cross-sectional view taken along line B-B ′ of the electronic component mounting substrate of (a). (A) is a top view of the conventional electronic component mounting board | substrate, (b) is sectional drawing in the C-C 'line | wire of the electronic component mounting board | substrate of (a). (A) is a top view which shows the other example of embodiment of the electronic component mounting board | substrate of this invention, (b) is sectional drawing in the A-A 'line of the electronic component mounting board | substrate of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 2 ... Electrode pad 3 ... Groove 3 '... Groove from which opening shape differs 4 ... Metallization layer 5 ... Metal Frame 6 ... Mounting part 7 ... Wiring conductor 8 ... Cover 9 ... Electronic components

Claims (4)

An insulating substrate having a rectangular mounting portion for mounting an electronic component on the main surface, an electrode pad formed at a corner of the mounting portion, and surrounding the mounting portion on the main surface of the insulating substrate The electrode pad has a shape in which the corners between the two sides of the quadrilateral along the metallization layer are chamfered. , the electronic component mounting, characterized in sites other than the corner portion of the metallized layer at the site, the Tei Rukoto the groove formed corresponding to the two sides between the metallized layer and the electrode pad of the main surface Substrate.   2. The electronic component mounting board according to claim 1, wherein a plurality of the grooves are formed, and one of them has an opening shape different from the other opening shape.   3. The electronic component mounting board according to claim 1, wherein an inner dimension of the groove gradually increases from a lower end to an upper end. 4.   4. The electronic component mounting substrate according to claim 1, an electronic component mounted on the mounting portion and having an electrode electrically connected to the electrode pad, and attached to the metallized layer And an electronic device.

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