JP2004063960A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device whose productivity and reliability are improved. <P>SOLUTION: A metal sealing ring 24 is installed on a ceramic substrate 2. An electronic component element 3 is arranged on the top surface of the ceramic substrate 2, positioned on the inner side of the sealing ring 24. A metal lid 5 is mounted on a top surface of the sealing ring 24. A region on the outer side of a contact part between the top surface of the sealing ring and a bottom surface of the lid is bonded by resistance welding, to seal an opening part of the sealing ring 24. In the electronic device constituted in this way, bonding is performed so that the contact width between the top surface of the sealing ring and the bottom surface of the lid of a corner part of the sealing ring is set wider than that of the other parts. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device used for hermetically sealing electronic component elements such as a piezoelectric element, a quartz oscillator, and a semiconductor element.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, electronic devices have been used to hermetically seal electronic component elements such as piezoelectric elements, quartz oscillators, and semiconductor elements.
[0003]
In such a conventional electronic device, for example, as shown in FIG. 7, a substantially rectangular seal ring 524 made of metal is attached to a ceramic base 52, and an electronic component is attached to the ceramic base 52 located inside the seal ring 524. The element 53 was disposed, the metal lid 55 was placed on the seal ring 524, and the upper surface of the seal ring 524 and the lower surface of the lid 55 were welded to seal the opening of the seal ring 524. Structures are known.
[0004]
The ceramic base 52 has a ring-shaped ceramic substrate 522 integrally attached to an upper surface of a plate-shaped ceramic substrate 521, and a cavity for accommodating the electronic component element 13 is formed inside the ring-shaped ceramic substrate 522. I have.
[0005]
A plating film made of Ni or the like is applied to the surfaces of the seal ring 524 and the lid 55, and the lower surface of the seal ring 524 is adhered to the upper surface of the ring-shaped ceramic substrate 522. The seal ring 524 is attached to the ceramic base 52 by brazing, and the plating film on the lid body surface and the plating film on the seal ring upper surface are melted by a conventionally known resistance welding (seam welding) to join the two. By doing so, the lid 55 and the seal ring 524 were joined.
[0006]
Note that, in the conventional electronic device shown in the figure, all the corners of the seal ring 524 and the lid 55 are rounded (rounded), so that the outer shapes of both are substantially similar. Is formed.
[0007]
[Problems to be solved by the invention]
By the way, in the above-described conventional electronic device, when the lid 55 is resistance-welded to the seal ring 524, the roller electrode of the resistance welding device is linearly scanned along each side of the lid 55. When the welding is performed by such a method, the roller electrode of the resistance welding device comes into contact with the corner of the lid 55 twice each. Therefore, the joining width at the corner tends to be wider than other parts, and when the contact width between the seal ring 524 and the lid 55 is substantially constant, melting occurs during resistance welding. The metal component (foreign matter) easily scatters inside the cavity 520, and if such foreign matter adheres to the electronic component element 53, the circuit wiring, and the like in the cavity 520, the characteristics of the electronic component element 53 change significantly. There has been a drawback that the productivity and reliability of the electronic device are significantly reduced due to, for example, a short circuit between circuit wirings.
[0008]
The present invention has been made in view of the above-described drawbacks, and an object of the present invention is to provide an electronic device capable of improving productivity and reliability.
[0009]
[Means for Solving the Problems]
In the electronic device of the present invention, a substantially rectangular seal ring made of metal is attached to a ceramic base, and an electronic component element is disposed on the ceramic base located inside the seal ring. An electronic device in which a metal lid is placed and an outer region of the contact portion between the upper surface of the seal ring and the lower surface of the lid is joined by resistance welding to seal an opening of the seal ring. The width of contact with the lower surface of the lid is wider at the corner of the seal ring than at other portions.
Further, the electronic device according to the present invention is characterized in that a non-joined portion having a width of 35 μm to 200 μm is provided around the inside of the joined portion in the contact portion.
[0010]
According to the electronic device of the present invention, since the contact width between the upper surface of the seal ring and the lower surface of the lid is made wider at the corner of the seal ring than at other portions, the joint at the corner of the seal ring is also formed. A non-joined portion can be secured inside. Accordingly, when the roller electrode of the resistance welding device is brought into contact with the lid and the lid and the seal ring are resistance-welded, even if the metal component (foreign matter) melted by the discharge spark tries to scatter toward the inside of the seal ring, The non-joined portion inside the seal ring effectively prevents foreign matter from entering, keeps the characteristics of the electronic component elements housed inside the seal ring good, and short-circuits between circuit wiring due to the foreign material. , The productivity and reliability of the electronic device can be improved.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1A is a plan view of the electronic device according to one embodiment of the present invention, with the lid removed and viewed from above, FIG. 1B is a cross-sectional view of the electronic device of FIG. 1A, and FIG. FIG. 1B is an enlarged view of a Z1 part, FIG. 3 is a plan view of the electronic device of FIG. 1 as viewed from above, and FIG. 4 is an enlarged view of a Z2 part of FIG. In this embodiment, a crystal oscillator using a crystal oscillator as an electronic component element will be described as an example.
[0012]
In the electronic device 1 shown in FIG. 1, a substantially rectangular seal ring 24 made of metal is mounted on a ceramic base 2, and the quartz oscillator 3 is mounted on the upper surface of the ceramic base 2 located inside the seal ring 24. The opening and the sealing ring 24 are formed by mounting and mounting a metal and a substantially rectangular lid 5A made of metal on the upper surface of the sealing ring 24, and joining the two by conventional resistance welding. It has a sealed structure.
[0013]
The ceramic base 2 is formed by integrally attaching a ring-shaped ceramic substrate 22 to an upper surface of a plate-shaped ceramic substrate 21. An inner surface of the ring-shaped ceramic substrate 22 and an upper surface of the plate-shaped ceramic substrate 21 located inside the ring-shaped ceramic substrate 22. A cavity 20 for accommodating the crystal resonator 3 is formed in a region surrounded by.
[0014]
The crystal resonator 3 housed in the cavity 20 includes a rectangular crystal substrate 31 cut along a predetermined crystal axis, excitation electrodes 33 formed on both main surfaces of the crystal substrate, and a crystal from the excitation electrodes. Lead electrodes 32 and 34 extending toward one end of the substrate; and connecting the lead electrodes 32 and 34 to an electrode pad 25 provided on the upper surface of the flat ceramic substrate 21 via a conductive adhesive 4. By doing so, the crystal resonator 3 is electrically and mechanically connected to the ceramic base 2.
[0015]
A metallized layer 221 is formed on the upper surface of the ring-shaped ceramic substrate 22, and the seal ring 24 is mounted on the ceramic base 2 by brazing the metallized layer 221 and the seal ring 24 with a brazing material 23. Be worn.
[0016]
Note that, on the lower surface of the ceramic base 2, there are provided terminal electrodes 26 which are electrically connected to the above-mentioned electrode pads 25 via via-hole conductors (not shown) or the like. When mounted on a mounting board such as a motherboard or a module board, it functions as a terminal for connecting the electronic device to an electric circuit on the mounting board.
[0017]
Such a ceramic substrate 2 is manufactured by, for example, a conventionally well-known ceramic green sheet laminating method or press molding using ceramic powder. The electrode pads 25, the terminal electrodes 26, the metallized layer 221 and the like on the ceramic substrate 2 are made of molybdenum or tungsten. A conductive paste containing a high melting point metal material is applied to the surface of the ceramic substrate 2 or the ceramic green sheet by screen printing or the like, which is conventionally known, and is baked at a high temperature.
[0018]
The seal ring 24 and the lid 5A disposed on the ceramic base 2 are made of, for example, a metal such as 42 alloy, Kovar, or phosphor bronze. The seal ring 24 is formed on the surface of the base 240 by a Ni plating layer 241 and Au. The plating layer 242 is formed by sequentially applying the coating, and the lid 5A is formed by applying the Ni plating layer 51A to the surface of the base material 50A.
[0019]
In the outer shape of the seal ring 24 and the lid 5A, the corners of the seal ring 24 are all rounded (rounded), whereas the corners of the lid 5A protrude outward. An overhang portion 5CN is formed, and when the lid 5A is placed on the seal ring 24, the contact width between the upper surface of the seal ring and the lower surface of the lid is larger at the corner of the seal ring 24 than at other portions. It is designed to be wide. In other words, when the electronic device is viewed in a plan view, the shortest distance between the inner periphery of the seal ring 24 and the outer periphery of the lid 5A is larger at the corner of the seal ring 24 than at other parts. .
[0020]
Therefore, when such a seal ring 24 and the lid 5A are resistance-welded along the outer periphery of the lid 5A, the roller electrode of the resistance welding device contacts the corner of the lid 5A twice, so that the corner portion is formed. Even if the joining width at the point is wider than the other parts, the contact width between the seal ring 24 and the lid 5A is wide at the corner, so that the inside of the joining part is sufficiently large as shown in FIG. A large-sized non-joined portion can be ensured, and metal components (foreign matter) melted during resistance welding can be effectively prevented from entering the cavity 20. As a result, the characteristics of the crystal resonator 3 housed in the cavity 20 are maintained favorably, and a short circuit between circuit wirings due to foreign matter is reduced as much as possible, thereby greatly improving the productivity and reliability of the electronic device. It becomes possible.
[0021]
In addition, it is preferable that the non-joined portion is provided with a width of 35 μm to 200 μm inside the joined portion.
[0022]
When welding the seal ring 24 and the lid 5A, the roller electrode of the resistance welding device is brought into contact with and scanned from above the outer peripheral end surface of the lid 5A, and the roller electrode is applied to the lid 5A and the seal ring 24. A large electric power is applied through the electrodes to generate a large amount of Joule heat between the lid 5A and the seal ring 24, and the thermal energy causes the Ni plating layer 51 on the lid surface and the Au plating layer on the seal ring surface. 242, the Ni plating layer 241 is melted.
[0023]
Further, when the crystal resonator 3 is used as an electronic component element as in the present embodiment, in order to effectively prevent corrosion and the like of the crystal resonator 3, inert gas such as nitrogen gas or argon gas is provided in the cavity 20. Preferably, a gas is enclosed, in which case the welding operation described above is performed in an inert gas atmosphere.
[0024]
It should be noted that the present invention is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the spirit of the present invention.
[0025]
For example, in the above embodiment, the seal ring 24 is attached to the ceramic base 2 by brazing the seal ring 24 to the metallized layer 221 on the upper surface of the ceramic base. As shown, the metallized layer 25 directly patterned on the upper surface of the ceramic base 2 may be used as it is as a sealing. In this case, the metallized layer 25 is preferably formed of a metal such as tungsten or molybdenum, and its surface is subjected to Ni plating, Au plating, or the like for welding to the lid 5B.
[0026]
In the above-described embodiment, a quartz oscillator is used as an electronic component element. However, instead of this, a piezoelectric oscillator such as a surface acoustic wave oscillator, a semiconductor element, or another electronic component such as a capacitor is used as an electronic component element. A component element may be used, and in such a case, the same effect as that of the above-described embodiment can be obtained.
[0027]
【The invention's effect】
According to the electronic device of the present invention, since the contact width between the upper surface of the seal ring and the lower surface of the lid is made wider at the corner of the seal ring than at other portions, the joint at the corner of the seal ring is also formed. A non-joined portion can be secured inside. Accordingly, when the roller electrode of the resistance welding device is brought into contact with the lid and the lid and the seal ring are resistance-welded, even if the metal component (foreign matter) melted by the discharge spark tries to scatter toward the inside of the seal ring, The non-joined portion inside the seal ring effectively prevents foreign matter from entering, keeps the characteristics of the electronic component elements housed inside the seal ring good, and short-circuits between circuit wiring due to the foreign material. , And the productivity and reliability of the electronic device can be improved.
[Brief description of the drawings]
FIG. 1A is a plan view of an electronic device according to an embodiment of the present invention with a lid removed and viewed from above, and FIG. 1B is a cross-sectional view of the electronic device of FIG.
FIG. 2 is an enlarged view of a part Z1 of the electronic device of FIG. 1;
FIG. 3 is a plan view of the electronic device of FIG. 1 as viewed from above.
FIG. 4 is an enlarged view of a Z2 part in FIG. 3;
FIG. 5 is a plan view showing a joint of the electronic device of FIG. 1;
FIG. 6 is a cross-sectional view of an electronic device according to another embodiment of the present invention.
FIG. 7A is a cross-sectional view of a conventional electronic device, and FIG. 7B is a plan view of the electronic device of FIG.
FIG. 8 is a plan view showing a joint of the electronic device of FIG. 7;
[Explanation of symbols]
1 ... Electronic device (crystal oscillator)
2 Ceramic substrate 20 Cavity 21 Flat ceramic substrate 22 Ring ceramic substrate 24 Seal ring 242 Ni plating layer 243 Au plating layer 3・ Electronic components (crystal oscillators)
5 lid 5CN overhang

Claims (2)

A substantially rectangular seal ring made of metal is mounted on the ceramic base, and the electronic component element is disposed on the ceramic base located inside the seal ring, and a metal lid is placed on the seal ring. In the electronic device in which the seal ring upper surface-the contact part outer region of the lid lower surface is joined by resistance welding to seal the opening of the seal ring,
An electronic device, wherein the contact width between the upper surface of the seal ring and the lower surface of the lid is wider at a corner of the seal ring than at other portions. 2. The electronic device according to claim 1, wherein a non-joined portion having a width of 35 μm to 200 μm is provided around the inside of the joined portion in the contact portion.

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