JP2000106404A - Manufacture of electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an electronic device in which cracks are not generated on an insulating substrate when a metal cover is electron-beam welded to the metallized metal layer of the insulating substrate, having an electronic component with a container of excellent airtightness and the electronic component housed in the device can be operated normally and stably for a long period. SOLUTION: An electronic component 1, an insulating substrate 2, having the mounting part 2a of the electronic component 1 on the upper surface and a frame-like metallized metal layer 5 surrounding the mounting part 2b, and a metal cover 3, in which the electronic component 1 is housed, are prepared. Then, the electronic component 1 is mounted on the mounting part 2a, and the metal cover 3 is mounted on the metallized metal layer pinching a soldering material 6 between them. Then, after the insulating substrate 2 has been preliminary heated up by irradiating the electron beam 7a having the output with which the soldering material 6 is not fused, on the upper surface of the metal cover 3, the metal cover 3 is junctioned to the metallized metal layer 5 by the soldering material 6 by irradiating an electron beam 7b of the output with which the soldering material is fused. The thermal impulse to the insulating substrate 2 is alleviated, and the generation of cracks can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electronic device in which electronic components such as a piezoelectric vibrator and a semiconductor element are hermetically accommodated in a container comprising an insulating base such as ceramics and a metal lid. is there.

[0002]

2. Description of the Related Art Electronic components such as a piezoelectric vibrator and a semiconductor element are air-tightly accommodated in a container for accommodating the electronic components to become an electronic device as a product.

[0003] Among such electronic devices, the most reliable one is an insulating base made of ceramics such as an aluminum oxide sintered body and having a mounting portion for mounting electronic components at the center of the upper surface, and an insulating substrate having the same. A metal frame made of an iron-nickel alloy or an iron-nickel-cobalt alloy attached to the upper surface of the base so as to surround the mounting portion; and an iron-nickel alloy or iron joined to the metal frame by seam welding. A type in which an electronic component is hermetically sealed inside a container made of a metal lid made of a nickel-cobalt alloy. In this type of electronic device, an electronic component is mounted on a mounting portion of an insulating base, and then a metal lid is mounted on a metal frame attached to the insulating base. It is manufactured by rolling while a pair of roller electrodes of a seam welding machine are in contact with each other, flowing a large current for welding between the roller electrodes, and seam-welding a metal lid to a metal frame.

In this type of electronic device, the metal frame attached to the insulating base is provided with a frame-shaped metallized metal layer on the upper surface of the insulating base so as to surround the mounting portion. After a nickel plating layer is applied to the metallized metal layer, it is attached by brazing to this with a brazing material such as silver brazing.

However, this type of electronic device is
When the metal lid is seam-welded to the metal frame attached to the insulating base, the moving speed of the roller electrode of the seam welding apparatus is as slow as at most 3 mm / sec. Seam welding to the frame takes a long time of about several seconds, and has the disadvantage of low productivity.

Furthermore, since a metal frame is required as a base metal for seam welding a metal lid to an insulating base, the height of the electronic device is increased by the metal frame, and the cost is high. There was also a disadvantage that it would be difficult.

In view of the above, there is provided a mounting portion for mounting an electronic component at the center of the upper surface and an aluminum oxide sintered body having a metallized metal layer having a thickness of about 10 to 20 μm surrounding the mounting portion at the outer peripheral portion of the upper surface. After preparing a container including an insulating base made of ceramics and a metal lid made of an iron-nickel alloy or an iron-nickel-cobalt alloy, mounting electronic components on a mounting portion of the insulating base, and then metalizing the insulating base. There has been proposed an electronic device in which an electronic component is hermetically sealed inside a container formed of an insulating base and a metal lid by electron beam welding a metal lid to a metal layer via a brazing material. .

In this type of electronic device, the metallized metal layer of the insulating base is coated with nickel plating to a thickness of 2 to 5 μm, and a metal cover is formed on the nickel-plated metallized metal layer. Is then placed with a brazing material in between, and then the electron beam is irradiated on the upper surface of the metal lid while moving along the frame-shaped metallized metal layer by a magnetic field. By melting the brazing material corresponding to the part irradiated with the electron beam in
The metal lid and the insulating base are joined.

According to such an electronic device, since the electron beam is irradiated while being moved by the magnetic field, it can be moved at a high speed of about 300 mm / sec or more. Can be welded to the metallized metal layer of the insulating substrate in a very short time of 0.1 second or less, so that the productivity is extremely excellent.

Furthermore, since a metal frame is not required as a base metal for welding, the height can be reduced accordingly and the cost is low.

[0011]

However, in an electronic device in which electronic components are hermetically accommodated in a container in which this type of metal lid is joined by electron beam welding, the metal lid is formed of a metallized metal of an insulating base. When an electron beam is welded to a layer, heat generated by the electron beam is transmitted to a portion of the insulating substrate corresponding to the portion irradiated with the electron beam, and this portion receives a thermal shock that locally becomes high in a very short time, For this reason, a crack may be formed in a portion of the insulating substrate corresponding to the portion irradiated with the electron beam. When such cracks are formed, the cracks are repeatedly subjected to temperature changes in the external environment for a long period of time, and thus progress to the outside of the insulating base. There has been a problem that normal and stable operation cannot be performed over a period.

The present invention has been devised in view of such a problem, and an object of the present invention is to prevent a crack from being formed in an insulating substrate when an electron beam welding is performed on a metal lid to a metallized metal layer of the insulating substrate. Another object of the present invention is to provide a method of manufacturing an electronic device that can operate a normal and stable electronic component housed therein for a long period of time by making a container for housing the electronic component extremely airtight.

[0013]

According to the present invention, there is provided a method of manufacturing an electronic device, comprising: an electronic component; a mounting portion on which the electronic component is mounted on a top surface; and a frame-like shape attached to surround the mounting portion. Preparing an insulating base having a metallized metal layer, and a metal lid joined to the metallized metal layer of the insulating base and accommodating the electronic component in a space between the insulating base and the insulating base; Mounting the electronic component on the mounting portion, mounting the metal lid on the metallized metal layer of the insulating base with a brazing material interposed therebetween, and an upper surface of the metal lid. Preheating the insulating base by irradiating at least one round of an electron beam along the frame-shaped metallized metal layer with an output electron beam that does not melt the brazing material, and forming the brazing material on the upper surface of the metal lid. Bonding the metal cover to the metallized metal layer via the brazing material by irradiating the molten metal beam at least one round along the frame-shaped metallized metal layer. It is a feature.

According to the method of manufacturing an electronic device of the present invention, the metal lid is joined to the metallized metal layer via the brazing material by irradiating the upper surface of the metal lid with an electron beam of an output that melts the brazing material. Before performing the heating, the upper surface of the metal lid is irradiated with an electron beam that does not melt the brazing material to preheat the insulating base, so that the metal lid is joined to the metallized metal layer via the brazing material. Since the insulating base is preliminarily warmed to some extent by the preliminary heating, the thermal shock applied to the insulating base can be reduced, thereby effectively preventing the occurrence of cracks in the insulating base.

[0015]

Next, the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view showing an example of an embodiment of an electronic device manufactured by the manufacturing method of the present invention. In FIG. 2, 1 is an electronic component, 2 is an insulating base, and 3 is a metal lid. It is. An electronic device is configured by hermetically housing the electronic component 1 such as a piezoelectric vibrator or a semiconductor element in a container including the insulating base 2 and the metal lid 3.

The electronic component 1 is, for example, a piezoelectric vibrator or a semiconductor element. In this example, the electronic component 1 has a plurality of electrodes (not shown) on its lower surface.

The insulating substrate 2 is a support for supporting the electronic component 1 and is made of a ceramic such as an aluminum oxide sintered body or an aluminum nitride sintered body. Of the recess A. The bottom surface of the concave portion A forms a mounting portion 2a for mounting the electronic component 1, and the electronic component 1 is mounted on the mounting portion 2a.

A metallized wiring layer 4 made of a sintered metal powder of tungsten, molybdenum, or the like, which extends from the upper surface of the mounting portion 2a to the lower surface of the insulating substrate 2, is formed on the insulating substrate 2.

The metallized wiring layer 4 functions as a conductive path for electrically leading each electrode of the electronic component 1 to the outside, and the electrode of the electronic component 1 is formed on the upper surface of the mounting portion 2a. They are electrically connected via an adhesive. The portion of the metallized wiring layer 4 extending to the lower surface of the insulating base 2 is electrically connected to a wiring conductor of an external electric circuit board (not shown) via, for example, solder.

Further, on the outer peripheral portion of the upper surface of the insulating base 2, a frame-shaped metallized metal layer 5 having a width of about 0.4 mm made of a sintered metal powder such as tungsten or molybdenum is mounted.
is formed so as to surround a. A metal lid 3 is joined to the metallized metal layer 5 by electron beam welding with a brazing material 6 interposed therebetween.

The metal lid 3 is made of, for example, an iron-nickel alloy, an iron-nickel-cobalt alloy, or the like.
The electronic component 1 is housed and hermetically sealed between the metallized metal layer 5 and the insulating substrate 2 by electron beam welding with a brazing material 6 interposed therebetween.

The brazing material 6 is made of a silver-copper alloy, a lead-tin alloy, a gold-tin alloy, an aluminum-silicon alloy, a copper-zinc alloy, a silver-copper-phosphorus alloy, a silver-indium-tin alloy, or the like. It functions as a joining material for joining the metal lid 3 to the metallized metal layer 5.

If the insulating substrate 2 has a thermal conductivity of 15 W / m · K or less at 100 ° C., it is difficult for such an insulating substrate 2 to conduct heat.
Is bonded to the preheated metallized metal layer 5 of the insulating substrate 2 by electron beam welding, even if the upper surface of the metal lid 3 is irradiated with an electron beam, heat generated by the electron beam is not easily transmitted to the insulating substrate 2. Therefore, the insulating substrate 2 does not reach a high temperature at which cracks occur. As a result, the occurrence of cracks in the insulating substrate 2 due to the thermal shock of the electron beam can be effectively prevented, and the container including the insulating substrate 2 and the metal lid 3 has extremely excellent airtightness. It becomes possible to operate the electronic component 1 housed therein normally and stably for a long period of time.

Further, since heat is hardly transmitted to the insulating base 2, heat energy by the electron beam is reduced.
Since a large amount does not escape to the side, welding can be performed while reducing the energy of the electron beam for melting the brazing material 6.

When the metal cover 3 is made of a non-magnetic metal, the metal cover 3 is not magnetized by being affected by an external magnetic field or rubbing against an external member. When joining by beam welding, the irradiation position of the electron beam does not shift due to the magnetic force of the metal lid 3, and the upper surface of the metal lid 3 is accurately irradiated with the electron beam and firmly joined. Can be.

Next, a method for manufacturing the above-described electronic device will be described with reference to FIGS. 1 (a) to 1 (c). 1 (a) to 1 (c) are cross-sectional views for each step for explaining a manufacturing method of the present invention. First, as shown in FIG. 1 (a), an electronic component 1, an insulating substrate 2, and a metal lid Prepare body 3.

The electronic component 1 is, for example, a piezoelectric vibrator or a semiconductor element, and has a plurality of electrodes (not shown) on its lower surface in this example.

As described above, the insulating base 2 has the mounting portion 2a on which the electronic component 1 is mounted at the center of the upper surface. Further, a frame-shaped metallized metal layer 5 is provided on the outer peripheral portion of the upper surface so as to surround the mounting portion 2a.

If the insulating substrate 2 is made of, for example, an aluminum oxide sintered body, a suitable organic binder and a solvent are added to and mixed with raw material powders of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide and the like. A plurality of ceramic green sheets are obtained by forming the ceramic slurry in the form of a slurry into a sheet by employing a conventionally known doctor blade method or calender roll method, and these are subjected to an appropriate punching process. A metal paste to be a metallized wiring conductor 4 or a metallized metal layer 5 is printed and applied on these ceramic green sheets in a predetermined pattern, and is laminated vertically.
Finally, it is manufactured by firing at a high temperature of about 1600 ° C. in a reducing atmosphere.

The metal paste for forming the metallized wiring conductor 4 and the metallized metal layer 5 is obtained by adding an appropriate organic binder and a solvent to a metal powder such as tungsten, for example, and adopts a conventionally known screen printing method. As a result, a predetermined pattern is printed and applied to the ceramic green sheet.

The metallized wiring layer 4 and the metallized metal layer 5 adhered to the insulating base 2 are plated with a metal having excellent corrosion resistance such as nickel and gold and excellent wettability with solder on the exposed surface. , The metallized wiring layer 4 and the metallized metal layer 5 can be effectively prevented from being oxidized and corroded, and the metallized wiring layer 4 and the electrodes of the electronic component 1 and the external electric circuit board can be effectively prevented. Of the metallized metal layer 5 and the metal lid 3 via the brazing material 6 by electron beam welding can be made strong.
Therefore, the metallized wiring layer 4 and the metallized metal layer 5
1μm to 20μm of metal with excellent corrosion resistance such as nickel and gold and excellent wettability with solder etc.
It is preferable to adhere to a thickness of.

The metal cover 3 is a substantially flat member made of, for example, an iron-nickel alloy or an iron-nickel-cobalt alloy, and a brazing material 6 is previously applied to the entire lower surface thereof.

Such a metal lid 3 is made of a silver-copper alloy, a lead-tin alloy or the like on the lower surface of a large-area plate-shaped base material made of an iron-nickel alloy or an iron-nickel-cobalt alloy. The brazing material is clad to a predetermined thickness by a conventionally known rolling method, plating method, or the like, and is punched into a predetermined shape by a conventionally known punching method so that the brazing material 6 is provided on the entire lower surface. Be produced.

Next, as shown in FIG. 1B, the electronic component 1 is mounted on the mounting portion 2a of the insulating base 2 and the metal cover 3 is interposed between the metallized metal layers 5 of the insulating base 2. It is placed with the material 6 interposed.

In order to mount the electronic component 1 on the mounting portion 2a of the insulating base 2, the electrodes of the electronic component 1 and the wiring conductors 4 of the insulating base 1 are bonded via a conductive adhesive such as silver-epoxy resin. The fixing method is adopted.

Then, as shown in FIG. 1 (c), an electron beam 7a having an output in which the brazing material 6 does not melt is applied to the upper surface of the metal cover 3 at least once along the frame-shaped metallized metal layer 5. Irradiation preheats the insulating substrate 2.

The preheating is performed, for example, when the metal lid 3 is made of an iron-cobalt-nickel alloy having a thickness of 0.1 mm, the upper surface of the metal lid 3 has a thickness of 1 to 3 mA · 30.
An electron beam having a diameter of about 0.1 to 0.2 mm at a power of about 90 W and a metallized metal layer 5 at a speed of about 300 mm / sec.
It is sufficient to irradiate at least one round while moving along. At this time, the temperature immediately below the metallized metal layer 5 of the insulating base 2 is about 50 to 200 ° C.

Finally, as shown in FIG.
The upper surface of the metal cover 3 is irradiated with an output electron beam 7b at which the brazing material 6 melts along the frame-shaped metallized metal layer 5 at least one round, and the metal cover 2 is applied to the metallized metal layer 5 by the brazing material 6. Thus, the electronic device is completed.

At this time, since the insulating base 2 is preheated by the preliminary heating, even if the upper surface of the metal lid 3 is irradiated with an electron beam 7b of an output in which the brazing material 6 melts, the heat of the electron beam 7b causes The temperature rise of the insulating base 2 can be reduced. As a result, the thermal shock due to the heat of the electron beam 7b is reduced, and the occurrence of cracks in the insulating substrate 2 is effectively prevented,
It is possible to provide an electronic device in which a container for housing electronic components has extremely excellent airtightness and can operate the electronic components housed therein in a normal and stable manner for a long period of time.

Thus, according to the method for manufacturing an electronic device of the present invention, an electronic device in which the electronic component 1 is housed with high airtight reliability inside a container including the insulating base 2 and the metal lid 3 can be obtained.

[0042]

[Example] [Example 1] At the center of the upper surface, the length is 2.2 mm and the width is
It has a substantially rectangular parallelepiped recess with a depth of 0.2 mm and a depth of 0.25 mm.
An insulating substrate made of a substantially square plate-shaped aluminum oxide sintered body having a length of 3 mm, a width of 2 mm, and a thickness of 0.5 mm having a metallized metal layer made of frame-shaped tungsten having a thickness of 20 μm and a thickness of 20 μm was prepared. . Then, a nickel plating layer having a thickness of 5 μm was applied to the surface of the metallized metal layer by an electrolytic plating method.

A 10 μm thick brazing material consisting of 72% by weight of silver and 28% by weight of copper was applied to the entire lower surface by a cladding method. The length was 3 mm, the width was 2 mm, and the thickness was 0.1 mm.
A flat metal lid made of an iron-nickel-cobalt alloy plate was prepared.

Then, a metal lid is placed on the metallized metal layer of the insulating substrate with a brazing material interposed therebetween, and an electron beam having a diameter of 0.2 mm and a power of 2 mA / 60 W is metallized on the upper surface of the metal lid. Preliminary heating was performed by irradiating two rounds while moving at a speed of 300 mm / sec along the metal layer.
Then, following this, 4 mA
The metallized metal layer and the metal lid are formed by irradiating an electron beam having a diameter of 0.2 mm with an output of 120 W along the metallized metal layer at a speed of 300 mm / sec. Were joined via a brazing material to obtain a sample of the electronic device of the present invention.

For comparison, an insulating base and a metal lid having the same dimensions and materials as described above were used, and after placing the metal lid on the metallized metal layer of the insulating base, the insulation was performed without preheating. With a power of 4 mA and 120 W on the upper surface of the base, the diameter is 0.2 mm.
The metallized metal layer and the metal lid are melted by irradiating one round with a 2 mm electron beam moving along the metallized metal layer at a speed of 300 mm / sec to melt the brazed material. This was joined to obtain a sample of an electronic device of a comparative example.

Incidentally, 25 samples of the present invention and 25 samples of the comparative example were produced.

Thereafter, the metal lid joined to each sample was dissolved and removed with nitric acid, and the presence or absence of cracks in the insulating substrate was visually inspected. As a result, cracks were confirmed in all the samples in the electronic device of the comparative example, whereas no cracks occurred in the sample of the electronic device of the present invention.

Example 2 The same insulating substrate as in Example 1 was prepared, and a brazing filler metal of 90% by weight of lead and 10% by weight of tin and having a thickness of 20 μm was clad on the entire lower surface as a metal lid. 3 mm in length and 2 mm in width,
A flat plate made of an iron-nickel-cobalt alloy plate having a thickness of 0.1 mm was prepared.

Then, a metal lid is placed on the metallized metal layer of the insulating base with a brazing material interposed therebetween, and an electron beam having a diameter of 0.2 mm and a power of 1.5 mA / 45 W is applied to the upper surface of the metal lid. Preheating was performed by irradiating two rounds while moving at a speed of 300 mm / sec along the metallized metal layer. Then, follow this with 2.5 mm on the top of the metal lid.
The metallized metal layer and the metal lid are formed by irradiating an electron beam having a diameter of 0.2 mm with a power of mA · 75 W along the metallized metal layer at a speed of 300 mm / sec. Were joined via a brazing material to obtain a sample of the electronic device of the present invention.

Twenty-five samples of the present invention were prepared, and the metal lids bonded to each sample were dissolved and removed with nitric acid, and the presence or absence of cracks in the insulating substrate was visually inspected. As a result, no cracks occurred in these electronic device samples of the present invention.

A sample of the electronic device of the present invention was manufactured under the same conditions using a brazing material consisting of 80% by weight of gold and 20% by weight of tin as the brazing material. When the presence or absence of cracks was examined, no cracks occurred in these electronic device samples of the present invention.

The above brazing material consisting of 90% by weight of lead and 10% by weight of tin and the brazing material consisting of 80% by weight of gold and 20% by weight of tin have relatively low melting points. By performing the heating, the flow of the brazing material becomes good, a good meniscus is formed without a gap between the insulating base and the metal lid, and the insulating base and the metal lid can be firmly joined. did it. In addition, since a good meniscus was formed, moisture and the like did not enter through the gap between the insulating base and the metal lid, and problems such as internal corrosion were successfully prevented.

Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes and improvements can be made without departing from the scope of the present invention.

[0054]

According to the electronic device manufacturing method of the present invention,
Before the metal lid is joined to the metallized metal layer via the brazing material by irradiating the upper surface of the metal lid with an electron beam that melts the brazing material, an electron beam with a power that does not melt the brazing metal is used. Since the insulating base is preheated by irradiating the upper surface of the lid body, since the insulating base is previously heated by the preheating when joining the metal lid to the metallized metal layer via the brazing material, Thereby, the thermal shock applied to the insulating base can be reduced.

As a result, the occurrence of cracks in the insulating base is effectively prevented, a good meniscus can be formed by the brazing material, and the container for housing the electronic components is made to have extremely excellent airtightness. In addition, it is possible to provide an electronic device that can normally and stably operate electronic components housed therein for a long period of time.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views for explaining steps of a method for manufacturing an electronic device according to the present invention.

FIG. 2 is a sectional view showing an example of an embodiment of an electronic device manufactured by the manufacturing method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic component 2 ... Insulating base 2a ... Mounting part 3 ... Metal cover 5 Metallized metal layer 6 Brazing filler metal 7a... An electron beam with an output in which the brazing material 6 does not melt 7b... An electron beam with an output in which the brazing material 6 melts

Claims (1)

[Claims] An insulating base having an electronic component, a mounting portion on which the electronic component is mounted, and a frame-shaped metallized metal layer attached so as to surround the mounting portion; A step of preparing a metal lid joined to the metallized metal layer and accommodating the electronic component in a space between the insulating base and a step of mounting the electronic component on the mounting portion of the insulating base; Placing the metal lid on the metallized metal layer of the insulating base with a brazing material interposed therebetween; and applying an electron beam having an output such that the brazing material does not melt on the upper surface of the metal lid. Preheating the insulating substrate by irradiating at least one round along the metallized metal layer in the shape of a metal, and applying an electron beam of an output that melts the brazing material on the upper surface of the metal lid to the frame-shaped metal. Bonding the metal cover to the metallized metal layer via the brazing material by irradiating the metalized metal layer at least one time along the metallized metal layer.