JPH08139426A - Surface mount electronic components - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a highly reliable surface mount type electronic component which is small in size and can be simplified in manufacturing. [Structure] There is a substrate 1A on which a lead-out electrode that is electrically connected to an external circuit is formed, and the lead-out electrode is provided with an element mounting pad portion 11
There is an element 3 provided with C, 12C, 13C, 14C, and an electrode 31, and a lead pad 312 of the element is provided with a bonding material pad portion 313 at one end thereof. And the bonding material pad portion of the lead electrode of the element are electromechanically bonded at least through a conductive bonding material 51 having elasticity such as a silicon-based bonding material, and the element is mounted on the substrate. In the surface mount type electronic component in which the lid 4 is sealed on the substrate on which the element is mounted, a redox agent such as Pd is mixed in the conductive bonding material having elasticity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type electronic component such as a crystal oscillator or a crystal filter.

[0002]

2. Description of the Related Art As a conventional example, a piezoelectric vibrator using a ceramic case will be described as an example. FIG. 5 is an exploded perspective view showing a conventional embodiment. The ceramic substrate 1A is made of alumina, is processed into a thin plate shape, and has four notches 1a, 1b, 1c, which form external terminals on its side surfaces.
1d is provided. On the ceramic substrate 1A, a lead electrode (not shown) is metallized from the four cutouts to the support mounting portion 13B (only a part is shown) that constitutes a conductive pad. A ceramic substrate 1B provided with a cutout 15B is further laminated on the ceramic substrate 1A. Then, by sintering these ceramic substrates 1A and 1B, an accommodation space is formed by the cutout 15B. The supports 21, 22, 23, and 24 are made of, for example, nickel silver, Cu-Ni-Zn alloy, or a metal plate such as SUS,
Each of them has a flat plate shape having substrate coupling portions 211, 221, 231, 241 and element mounting portions 212, 222, 232, 242, and a rising portion coupling these components. These support element mounting parts 212, 222, 2
32 and 242 toward the center side in the substrate longitudinal direction formed by the cutout 15B, and the substrate coupling portion 2
11, 221, 231, and 241 are mounted on the support mounting portion 13B (only part of which is shown) of the substrate, and electromechanical bonding is performed by a method such as laser welding. In this way, the supports 21, 22, 23, 24 are fixed only at the respective support mounting portions at both ends in the substrate longitudinal direction, and extend slightly obliquely upward from the support mounting portions toward the center side. . The excitation electrodes 31 are provided on the front and back surfaces.
The rectangular crystal plate 3 on which the back surface (not shown) is formed is attached to the support element mounting portions 212, 222, and 23.
2 and 242, and in the first embodiment of the present invention, either (or both) of the supports 21 and 24 and the excitation electrode 31 are provided on either side (or both) of the supports 22 and 23 and the back surface side. The excitation electrode is at least electrically connected by an epoxy-based or polyimide-based conductive bonding material. Then, the support 4 and the ceramic substrate in which the crystal plate is housed are covered with the lid 4 and hermetically sealed by a technique such as seam welding.

[0003]

In recent years, surface mount type electronic parts have been reduced in weight, thickness and size, and are no exception in the field of piezoelectric vibrators such as crystal oscillators and crystal filters. Is the current situation. However, considering heat resistance, temperature characteristics, impact resistance, etc., it was necessary to attach a support between the substrate and the piezoelectric plate via a conductive bonding material. Even if the shape of the built-in piezoelectric plate becomes small, the height or the support width of the support has been an obstacle to weight reduction, thickness reduction, and size reduction of the piezoelectric vibrator as a surface mount electronic component. Moreover, in the process of forming the support, the process is complicated, the equipment is diversified, and the manufacturing cost is increased.

Therefore, an object of the present invention is to provide a highly reliable surface mount type electronic component which is small in size and can be simplified in manufacturing.

[0005]

Therefore, the surface mount type electronic component of the present invention has a substrate on which an extraction electrode is formed which is electrically connected to an external circuit, the extraction electrode is provided with an element mounting pad portion, and the main electrode is provided. And there is an element provided with a lead electrode,
A bonding material pad portion is provided at one end of the lead electrode of the element. The element mounting pad portion of the extraction electrode and the bonding material pad portion of the lead electrode of the element are at least conductive materials having elasticity such as a silicon-based bonding material. Electromechanically bonded via a conductive bonding material, the element is mounted on the substrate, in the surface mount type electronic component formed by sealing a lid on the substrate on which the element is mounted, A redox agent such as Pd was mixed into the conductive bonding material having elasticity. Then, the proportion of Pd with respect to the conductive bonding material is 2 to 8%.

The conductive bonding material having elasticity is applied to the substrate once and then the element is mounted, and at least applied again to bond the element.

At least one surface of the bonding material pad portion of the lead electrode of the element or the element mounting pad portion of the substrate is made of Ag.

Further, at least one of the bonding material pad portion of the lead electrode of the element or the element mounting pad portion of the substrate is formed with at least a portion where the element is exposed.

[0009]

According to the first aspect of the present invention, since O ₂ in the conductive bonding material is removed, the conductivity (metal piece or metal ball) is not deteriorated (the conductivity is lowered by oxidation).

According to claim 2, O in the conductive bonding material
_{Since 2} is removed, the conductivity (metal piece or metal sphere) is not deteriorated (the conductivity decreases due to oxidation).

According to the third aspect of the present invention, the element is mounted on the conductive bonding material once applied, and then the conductive bonding material is applied again to cure and bond, so that the mounting accuracy and the bonding strength can be improved. .

According to claim 4, since Ag is relatively less likely to oxidize than Al or the like, an oxide film is less likely to be formed on the same electrode, and the conductivity with the conductive bonding material is less likely to decrease. Further, since it is well compatible with the conductive bonding material, it is possible to perform stronger electromechanical bonding between the substrate and the element.

According to claim 5, the wettability between the exposed portion of the element and the conductive bonding material or between the exposed portion of the substrate and the conductive bonding material is stronger, and the substrate and the element are even stronger. It is possible to perform various mechanical joining.

According to claim 6, the wettability between the exposed portion of the element and the conductive bonding material or the exposed portion of the substrate and the conductive bonding material is stronger, and the substrate and the element are even stronger. It is possible to perform various mechanical joining.

[0015]

Next, a first embodiment of the present invention will be described by taking a surface mount type piezoelectric vibrator using a ceramic case as an example. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG. 2 is a sectional view of the assembled state of FIG. The ceramic substrate 1A is made of alumina, is processed into a thin plate shape, and is provided with four notches 1a, 1b, 1c, and 1d forming external terminals on its side surface. On the ceramic substrate 1A, element mounting pad portions 11C, 12C, which form a conductive pad from the four notches,
13C and 14C, the extraction electrode (Ag
Etc.) have been metallized. A ceramic substrate 1C provided with a cutout 15C is further laminated on the ceramic substrate 1A. Then, by sintering these ceramic substrates 1A and 1C, an accommodation space is formed by the cutout 15C. And
The element mounting pad portions 11C, 12C, 13C, 14C
An element mounting base 51 of the conductive bonding material is formed by applying a conductive bonding material on the exposed substrate portion 131C (only a part of which is shown). The conductive bonding material forming the element mounting base 51 is made of a silicon resin adhesive, contains, for example, thin plate-like Ag or spherical Ag as the conductor portion, and contains 2 to 8% of Pd as the redox agent. It is The rectangular crystal plate 3 has Al excitation electrodes 31 and 32 and a lead electrode 3 formed on the front and back surfaces by a sputtering deposition method or the like.
12 (the back side is not shown) is formed,
Further, the bonding material pad portion 31 in which the element exposure portions 314 and 324 in the shape of oval cutouts are provided at the end portions of the lead electrodes
3, 323 are formed. Further, with respect to the bonding material pad portions 313 and 323, Ag is vapor-deposited using a mask having the same shape. Then, the rectangular crystal plate 3 is mounted on the element mounting base 51, and the same silicon resin-based conductive bonding material 52 is used as the element exposed portion 31 of the crystal plate 3.
By coating and hardening the bonding material pad portions 313 and 323 including 4,324, the electro-mechanical bonding between the crystal plate 3 and the element mounting base 51 by the conductive bonding material is performed. A lid 4 on the ceramic substrate that accommodates the above
And airtightly sealed by a technique such as seam welding.

Although Pd is used as the redox agent in the first embodiment of the present invention, Ni, Cu or the like may be used. Further, although the element exposed portion has an oval cutout shape, it may have a circular cutout shape, an elliptical cutout shape, or a polygonal shape such as a triangular cutout shape or a square cutout shape. . Further, Ag is vapor-deposited only on the bonding material pad portion, but Ag may be vapor-deposited on all electrode regions such as the excitation electrode and the lead electrode. That is, in the case of a multi-layer electrode structure having at least two layers, the uppermost electrode may be Ag. For example, it is preferable to set Cr on the upper layer of Al and Ag on the upper layer.

Next, as a second embodiment, a surface mount type piezoelectric vibrator using a ceramic case will be described as an example. A multi-electrode crystal plate called a monolithic crystal filter was used as the crystal plate. FIG. 3 is an exploded perspective view showing a second embodiment of the present invention, and FIG. 4 is a sectional view of the assembled state of FIG. The same parts as those in the first embodiment are designated by the same reference numerals. The ceramic substrate 1A is made of alumina, is processed into a thin plate shape, and has four notches 1a, 1b, 1c, 1 which form external terminals on its side surfaces.
d is provided. On this ceramic substrate 1A,
From the four notches to the element mounting pad portions 11C, 12C, 13C and 14C that form the conductive pads, a lead electrode (not shown) (Ag or the like) is metallized. A ceramic substrate 1C provided with a cutout 15C is further laminated on the ceramic substrate 1A. Then, by sintering these ceramic substrates 1A and 1C, an accommodation space is formed by the cutout 15C. Then, the element mounting pad portion 11C,
12C, 13C, 14C substrate exposed portions 112C, 122
An element mounting base 51 of the conductive bonding material is formed by applying a conductive bonding material on C (only a part is shown) and curing it. The conductive bonding material forming the element mounting base 51 is made of a silicon resin adhesive, contains, for example, thin plate-like Ag or spherical Ag as the conductor portion, and contains 2 to 8% of Pd as the redox agent. It is The rectangular crystal plate 3 has excitation electrodes 33 and 34 and a common electrode 35, and a lead electrode 3 on which Cr is deposited on the upper layer of Al and Ag is deposited on the upper layer by sputtering deposition method or the like on the front and back surfaces.
32, 342 (the back surface is not shown) are formed, and bonding material pad portions 333, 343, 353 in which circular element exposed portions 334, 344, 354 are further provided at the end portions of the lead electrodes. Are formed. Then, the rectangular crystal plate 3 is mounted on the element mounting base 51, and the same silicon resin-based conductive bonding material 52 as described above is bonded to the bonding material pad portion 333 of the crystal plate 3 including the element exposed portions 334, 344 and 354. , 343, 353 and cured to electrically and mechanically bond the crystal plate 3 and the element mounting base 51 with the conductive bonding material. The lid 4 is put on the ceramic substrate containing the above and hermetically sealed by a technique such as seam welding.

In the second embodiment of the present invention, Pd is used as the redox agent, but Ni, Cu or the like may be used. Further, although the element exposed portion has a circular shape, it may have an elliptical shape, an oval shape, or the like, and a polygonal shape such as a triangular shape or a quadrangular shape does not pose any particular problem.

In the first and second embodiments of the present invention, the crystal oscillator and the crystal filter are mentioned, but they can also be applied to a crystal oscillator, a surface acoustic wave element, a piezoelectric ceramic oscillator. It goes without saying that it can be diverted to a piezoelectric ceramic filter, a capacitor element, a pyroelectric element, or the like. Further, it goes without saying that not only the rectangular element but also a disk-shaped element can be implemented.

[0020]

EFFECTS OF THE INVENTION According to claim 1 and claim 2, the conductivity (metal piece or metal sphere) is deteriorated because the O ₂ in the conductive bonding material is removed (the conductivity decreases due to oxidation).
A support structure with high impact resistance can be obtained without causing the above. Further, the weight, thickness, and size of the electronic component can be reduced without considering the conventional support space. Moreover, simplification can be achieved in manufacturing without considering the conventional support forming process.

According to the third aspect of the present invention, the element is mounted on the conductive bonding material once applied, and then the conductive bonding material is applied again to cure and bond, so that mounting accuracy and bonding strength can be improved. .

According to claim 4, since Ag is relatively less likely to oxidize than Al or the like, an oxide film is less likely to be formed on the same electrode, and the conductivity with the conductive bonding material is less likely to decrease. Further, since it is well compatible with the conductive bonding material, it is possible to perform stronger electromechanical bonding between the substrate and the element.
Therefore, it is possible to obtain a more reliable support structure with improved impact resistance and strength.

According to claims 5 and 6, the wettability between the exposed portion of the element and the conductive bonding material or the exposed portion of the substrate and the conductive bonding material is stronger, and the substrate and the element are more familiar. This enables even stronger mechanical joining with. Therefore, it is possible to obtain a more reliable support structure with further improved impact resistance and strength.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the assembled state of FIG.

FIG. 3 is an exploded perspective view showing a second embodiment of the present invention.

4 is a cross-sectional view of the assembled state of FIG.

FIG. 5 is a perspective view of a disassembler showing a conventional example.

[Explanation of symbols]

 1A, 1B, 1C ... Ceramic substrate 21, 22, 23, 24 ... Support 3 ... Crystal plate 4 ... Lid 51, 52 ... Silicon resin-based conductive bonding material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H03H 9/13 H04R 17/00

Claims (6)

[Claims] 1. A lead of the element, wherein there is a substrate on which an extraction electrode is formed which is electrically connected to an external circuit, an element mounting pad portion is provided on the extraction electrode, and an element is provided on which a main electrode and a lead electrode are provided. A bonding material pad portion is provided at one end of the electrode, and the element mounting pad portion of the extraction electrode and the bonding material pad portion of the lead electrode of the element are electromechanical via a conductive bonding material having at least elasticity. In the surface mounting type electronic component, which is bonded to the above, the element is mounted on the substrate, and the lid is sealed on the substrate on which the element is mounted, the conductive bonding material having elasticity is oxidized. A surface mount electronic component characterized by containing a reducing agent. 2. A silicon-based bonding material is used as the elastic conductive bonding material, and Pd is used as the redox agent.
The surface mount type electronic component according to claim 1, wherein the surface mount electronic component is mixed. 3. The conductive bonding material having elasticity is applied to the substrate once to mount an element, and at least applied again to bond the element. Surface mount electronic components. 4. The surface according to claim 1, wherein at least one surface of the bonding material pad portion of the lead electrode of the element or at least one of the element mounting pad portion of the substrate is Ag. Mounted electronic components. 5. A bonding material pad portion of a lead electrode of a device,
Alternatively, at least one of the device mounting pad portions of the substrate is provided with at least a portion where the device or the substrate is exposed, which is a surface mount electronic component. 6. A bonding material pad portion of a lead electrode of a device,
5. The surface mount type electronic device according to claim 1, wherein at least one of the element mounting pad portions of the substrate is formed with at least a portion where the element or the substrate is exposed. parts.