JP2004111847A - Substrate for mounting electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for mounting electronic component which can obtain an electronic device of high airtight reliability. <P>SOLUTION: The substrate for mounting electronic component has a mount part 4 for mounting an electronic component 7 in the central part of the upper surface of a substantially square insulating substrate 1 and a substantially square frame-like brazing metallized layer 2 in an outer circumferential part, and is formed by bonding a metallic frame body 6 to the brazing metallized layer 2 by a brazing material. In the substrate for mounting an electronic component, the central part of a pair of facing inner circumferential sides of the brazing metallized layer 2 projects toward the mount part 4 and the projecting portion 5 is covered with the brazing material. It is possible to form a fillet 10 of the brazing material sufficiently between the projecting portion 5 and the metallic frame body 6 for reinforcing junction between the brazing metallized layer 2 and the metallic frame body 6, so that the metallic frame body 6 can be prevented from peeling due to the stress in seam weld. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a small electronic component mounting board used for an electronic component storage package for storing electronic components therein.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, small electronic component mounting substrates used for electronic component housing packages for housing electronic components such as semiconductor elements and piezoelectric vibrators are made of aluminum oxide-based sintered bodies, aluminum nitride-based sintered bodies, and mullite-based materials. It is made of a ceramic material such as a sintered body or glass ceramic, and has a concave mounting portion for accommodating electronic components in the center of the upper surface, and a plurality of metallized wiring conductors extending from the inside of the mounting portion to the outer periphery of the lower surface. An insulating substrate having a square frame-shaped brazing metallization layer attached so as to surround the mounting portion, and a brazing material such as silver brazing surrounding the mounting portion in the brazing metallization layer of the insulating substrate. And a substantially square frame-shaped metal frame for sealing made of a metal such as an iron-nickel-cobalt alloy brazed.
[0003]
According to the conventional electronic component mounting board, the electronic component is mounted on the bottom surface of the mounting portion of the insulating base, and the electrodes of the electronic component are electrically connected to the metallized wiring conductor in the mounting portion by, for example, wire bonding. , And then a metal lid is welded to the upper surface of the metal frame for sealing by a seam welding method, thereby forming a container comprising the insulating base, the metal frame for sealing, and the metal lid. An electronic component is hermetically sealed inside the device, thereby forming an electronic device as a product.
[0004]
Brazing between the metallizing layer for brazing and the metal frame is performed by positioning and setting the metal frame on the brazing metallizing layer via a preform of a brazing material such as silver brazing, and in a furnace for brazing. Heating is performed by spreading the brazing material between the brazing metallization layer and the metal frame and spreading a certain amount of the brazing material so as to form a fillet on the side surface of the metal frame.
[0005]
[Patent Document 1]
JP 2001-291796 A
However, in such electronic component mounting substrates, the size of the electronic devices has become extremely small, on the order of several mm square, in accordance with the demand for miniaturization of electronic devices. The width of the brazing metallization layer has become extremely narrow at 300 μm or less. Also, the width of the brazing metallization layer has become extremely narrow so that the dimensions of the electronic components to be housed can be made larger than the external dimensions of the electronic component mounting board.
[0007]
An electronic component formed by brazing a metal frame for sealing having a width of about 0.15 to 0.45 mm to the brazing metallization layer having a width of about 0.2 to 0.5 mm as described above. In the mounting substrate, the width of the joining surface between the brazing metallization layer and the metal frame is narrow, and the distance between the edge of the brazing metallization layer and the edge of the metal frame is 0.05 mm. When the metal lid is welded on the metal frame for sealing by the seam welding method, the sealing is performed after welding, because the filler is very narrow, such as 0.35 mm, and the fillet of the brazing material is not sufficiently formed in this narrow area. A large stress is applied to the metallizing layer for brazing due to a large thermal contraction of the metal frame for metal and the metal lid, and the metal frame is peeled off from the metallizing layer for brazing due to this stress. Tower Airtightness reliability of the electronic device using the use substrate had a problem that may be significantly lowered.
[0008]
Normally, in order to reduce the size of the insulating substrate and to secure as large a storage capacity as possible for the electronic components to be stored, the brazing metallization layer and the metal frame are provided on at least two inner peripheral wall surfaces thereof. Are formed so as to be flush with each other on the upper and lower surfaces, so that a fillet of a brazing material is particularly difficult to be formed on the inner peripheral wall surface side. The peripheral wall side is weak.
[0009]
The present invention has been devised in view of such a problem, and an object thereof is to weld a metal lid to a metal frame for sealing by a seam welding method or the like, and then form a metal frame for sealing and a metal lid. Even if a large stress is applied to the brazing metallized metal layer due to a large thermal contraction of the body, the sealing metal frame and the insulating substrate do not peel off, and the hermetic sealing of the obtained electronic device is completely completed. An electronic component mounting board suitable for an electronic component storage package capable of obtaining an electronic device with high hermetic reliability that enables normal and stable operation of electronic components housed therein for a long period of time. Is to provide.
[0010]
[Means for Solving the Problems]
The electronic component mounting substrate of the present invention has a mounting portion for mounting an electronic component at the center of the upper surface of the substantially square insulating substrate, and has a substantially square frame-shaped brazing metallizing layer on the outer peripheral portion. An electronic component mounting substrate formed by joining a metal frame to the metallizing layer for brazing with a brazing material, wherein a central portion of a pair of inner peripheries of the metalizing layer for brazing faces the mounting portion. And these projecting portions are covered with the brazing material.
[0011]
According to the electronic component mounting board of the present invention, a portion protruding toward the mounting portion so as to face each other is provided at a central portion of a pair of opposed inner peripheral sides of a brazing metallization layer for brazing a metal frame. Since the protruding portion is covered with the brazing material, the protruding portion and the metal frame form a fillet of the brazing material similarly to the outer peripheral portion of the brazing metallization layer. After joining the metal lid to the metal frame for sealing by the seam welding method, the stress generated by the thermal contraction of the metal frame for sealing and the metal lid is brazed. Even if the stress is applied to the metallization layer, the stress is well dispersed in the protruding portion of the brazing metallization layer and the fillet of the brazing material on the outer peripheral portion. It is possible to effectively prevent the peeling, brazing metallized layer can also be effectively prevented from being separated from the insulating substrate.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an electronic component mounting board of the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1A is a top view showing an example of an embodiment of an electronic component mounting board according to the present invention, and FIG. 1B is a sectional view thereof. In these figures, 1 is an insulating substrate, 2 is a metallized layer for brazing, 3 is a metallized wiring conductor, 4 is a mounting portion for mounting an electronic component 7, and 5 is a mounting portion 4 of the metallized layer 2 for brazing. A portion 6 protruding toward is a metal frame.
[0014]
The insulating substrate 1 is formed by laminating three ceramic layers made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, and a glass ceramic. It has a substantially square shape with a thickness of about 2 to 20 mm and a thickness of about 0.5 to 3 mm. A substantially rectangular concave mounting portion 4 for mounting and housing electronic components is provided at the center of the upper surface, and tungsten, molybdenum, copper, silver, or the like extends from the mounting portion 4 to the lower surface via the side surface. A plurality of metallized wiring conductors 3 made of metallized metal powder are deposited.
[0015]
On the upper surface of the insulating substrate 1, a substantially square frame-shaped brazing metallization layer 2 made of metal powder of metal such as tungsten, molybdenum, copper, silver or the like is provided so as to surround the concave mounting portion 4. 1 is formed so as to be separated from the outer periphery by about 0.05 to 0.2 mm. In this example, the insulating substrate 1 is formed by laminating three ceramic layers, but the insulating substrate 1 may be formed by laminating four or more ceramic layers.
[0016]
In such an insulating substrate 1, if the ceramic layer is made of an aluminum oxide sintered body and the metallized wiring conductor 5 and the brazing metallized layer 6 are made of tungsten metallized, aluminum oxide, silicon oxide, magnesium oxide, An appropriate organic binder, a solvent, a plasticizer, and the like are added to and mixed with a raw material powder such as calcium oxide to form a slurry, and this is formed into a sheet by a sheet forming method such as a doctor blade method, thereby forming a plurality of ceramics. Green sheets are obtained, and then the ceramic green sheets are subjected to appropriate punching, and a metal paste to be the metallized wiring conductor 3 and the metallized layer 2 for brazing is applied by printing. Laminate up and down and fire the laminate It is manufactured by.
[0017]
Further, the metallized wiring conductor 3 attached and formed from the bottom surface of the mounting portion 4 to the lower surface via the side surface of the insulating substrate 1 electrically connects each electrode of the electronic component 7 mounted on the mounting portion 4 to an external electric circuit. Each electrode of the electronic component 7 is electrically connected to a bottom portion of the mounting portion 4 through an electrical connection means such as wire bonding, for example. Are electrically connected to an external electric circuit board (not shown) via solder or the like.
[0018]
The exposed surface of the metallized wiring conductor 3 is provided with a material that prevents the metallized wiring conductor 3 from being oxidized and corroded and has a strong connection between the metallized wiring conductor 3 and each electrode of the electronic component 7 and a connection with the external electric circuit board. In order to do so, a nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are usually sequentially applied.
[0019]
Further, the brazing metallization layer 2 provided on the upper surface of the insulating substrate 1 so as to surround the concave mounting portion 4 functions as a base metal for joining the metal frame 6 to the insulating substrate 1. The metallized layer 2 for brazing has a thickness of about 10 to 30 μm, a width of each side of about 0.2 to 0.5 mm, and has a substantially square frame-shaped metal frame surrounding the mounting portion 4 on its upper surface. 6 is brazed via a brazing material such as silver brazing.
[0020]
The sealing metal frame 6 brazed to the brazing metallization layer 2 via a brazing material such as silver brazing is made of a metal such as an iron-nickel alloy or an iron-nickel-cobalt alloy. The cover 8 functions as a base metal member for bonding the cover 8 to the insulating substrate 1. The metal frame 6 for sealing has an inner circumference substantially the same size as the opening of the mounting portion 4, a thickness of about 0.1 to 0.5 mm, and a width of each side of 0.15 to 0.45 mm. It is about.
[0021]
In the electronic component mounting board of the present invention, a pair of inner peripheral central portions of the brazing metallization layer 2 facing each other project toward the mounting portion 4. Since the central portions of a pair of inner peripheries of the brazing metallization layer 2 facing each other protrude toward the mounting portion 4, when the metal frame 6 is brazed to the brazing metallization layer 2, The projecting portion 5 is also covered with the brazing material, and the fillet 10 of the brazing material can be formed with a sufficient width from the projecting portion 5 to the metal frame 6.
[0022]
Therefore, similarly to the fillet 9 on the outer peripheral portion of the brazing metallization layer 2, the brazing metallization layer 2 and the metal frame 6 are formed by joining the brazing material fillet 10 with the protruding portions 5. Therefore, after the metal lid 8 is welded to the metal frame 6 by the seam welding method, the stress generated by the thermal contraction of the metal frame 6 and the metal lid 8 is applied to the brazing metallization layer 2. Even if the stress is applied, the stress is well dispersed in the fillet 10 formed at the protruding portion 5 of the brazing metallization layer 2 and the fillet 9 on the outer peripheral portion of the metal frame 6, and as a result, the metal frame Separation of the body 6 from the insulating substrate 1 is effectively prevented.
[0023]
By providing such protruding portions 5 at the central portions of a pair of inner peripheral surfaces of the brazing metallization layer 2 so as to face each other, a direction parallel to and perpendicular to the pair of inner peripheral surfaces facing each other. In both directions, the joining between the brazing metallization layer 2 and the metal frame 6 can be effectively reinforced, and the metal frame 6 is brazed by the stress when the metal lid 8 is welded. Peeling from the layer 2 (and the insulating substrate 1) can be prevented.
[0024]
In this case, since the protruding portion 5 is provided only on one side of the inner periphery of the brazing metallization layer 2, the metal frame 5 is provided between the side where the protruding portion 5 is provided and the side where the protruding portion 5 is not provided. Since the brazing strength of the metal frame 5 greatly differs, the metal frame 5 peels off from the side where the protruding portion 5 is not provided. Therefore, the protruding portion 5 of the brazing metallization layer 2 needs to be provided on a pair of opposed inner peripheries. Moreover, since the peeling between the metallizing layer 2 for brazing and the metal frame 5 is particularly likely to occur on the inner peripheral side of the center of the side where the narrow bonding region continues, the projecting portion 5 is used for brazing. It is necessary to provide the metallized layer 5 at the central portion of the inner periphery.
[0025]
In the case where the shape of the brazing metallization layer 2 is a rectangular frame, the metal frame 6 is formed by forming a protruding portion 5 at the center of a pair of inner peripheries facing each other on the long side. This is particularly effective for preventing peeling of the metal frame 6 on the long side where the bonding strength with the attachment metallized layer 2 is relatively weak. Therefore, when the brazing metallization layer 2 has a rectangular frame shape, it is preferable to form the protruding portion 5 at the center of the pair of inner peripheries on the long side.
[0026]
The projecting portion 5 is preferably formed in a region where the metallized wiring conductor 3 for making an electrical connection with the electronic component 7 is not formed. By forming the metallized wiring conductor 3 in a region where the metallized wiring conductor 3 is not formed, the projecting portion 5 effectively prevents the efficient electrical connection between the metallized wiring conductor 3 and the electronic component 7 from being hindered. can do.
[0027]
In order to improve the wettability between the metallizing layer 2 for brazing and the brazing material, a nickel plating layer having a thickness of about 0.5 to 5 μm is usually provided on the surface of the metallizing layer 2 for brazing. Are pre-applied before brazing.
[0028]
Thus, according to the electronic component mounting board of the present invention as described above, the electronic component 7 is mounted in the mounting portion 4 of the insulating substrate 1 and the electrodes of the electronic component 7 and the metallized wiring conductors 3 are bonded with bonding wires or the like. After being electrically connected to the metal frame 6 for sealing, the metal cover 8 is joined to the metal frame 6 for sealing by seam welding, so that the inside of the container including the insulating substrate 1, the metal frame 6 and the metal lid 8 is placed inside. By hermetically sealing the component 7, an electronic device having excellent airtight reliability can be obtained.
[0029]
It should be noted that the present invention is not limited to the above-described embodiment, and various changes may be made without departing from the scope of the present invention. For example, the shape of the insulating substrate and the brazing metallization layer is not a rectangular shape but a square shape, and a pair of protruding portions are provided at the center of a pair of inner peripheries of the brazing metallization layer so as to face each other. May be used.
[0030]
【The invention's effect】
According to the electronic component mounting board of the present invention, a substantially square frame-shaped brazing metallization layer having a mounting portion for mounting an electronic component is provided at the center of the upper surface of the substantially square insulating substrate and the outer peripheral portion is provided. An electronic component mounting board formed by joining a metal frame to the metallizing layer for brazing with a brazing material, wherein a pair of inner peripheral central portions of the brazing metallizing layer facing each other face a mounting portion. Since these protruding portions are covered with the brazing material, the protruding portions and the metal frame form a fillet of the brazing material in the same manner as the outer peripheral portion of the brazing metallization layer. After joining the metal lid to the metal frame for sealing by the seam welding method, the stress generated by the thermal contraction of the metal frame for sealing and the metal lid is brazed. For metalla Even if the stress is applied to the brazing layer, the stress is well dispersed in the fillet formed at the protruding portion of the brazing metallization layer and the fillet of the brazing material on the outer peripheral portion of the metal frame for sealing. Separation of the metal frame for sealing from the insulating substrate can be effectively prevented, and separation of the metallized layer for brazing from the insulating substrate can also be effectively prevented.
[0031]
Therefore, when the electronic component is sealed inside the container including the insulating substrate, the sealing metal frame, and the metal lid, the electronic component housed therein can operate normally and stably for a long period of time. Becomes possible.
[Brief description of the drawings]
FIGS. 1A and 1B are a top view and a cross-sectional view, respectively, showing an example of an embodiment of an electronic component mounting board according to the present invention.
[Explanation of symbols]
1. Insulating substrate 2 Brazing metallization layer 3 Metallization wiring conductor 4 Mounting part 5 Projecting part 6 -Metal frame 7-Electronic components 8-Metal cover 9-Fillet (outer periphery)
10 Fillet (projected part)

Claims (1)

A mounting portion for mounting an electronic component is provided at the center of the upper surface of the substantially square insulating substrate, and a substantially square frame-shaped metallizing layer for brazing is provided on the outer peripheral portion. An electronic component mounting board formed by joining bodies with a brazing material, wherein a central portion of a pair of inner peripheries of the brazing metallization layer facing each other protrudes toward the mounting portion, and these protruding portions are An electronic component mounting board, which is covered with the brazing material.

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