JP2000150689A - Electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic part exhibiting an enough hermeticity. SOLUTION: An electronic part is provided with a case 1 having an opening, a SAW device 3 housed in the case 1, a metal layer 2 placed on the edge of the opening of the case 1 and a lid 5 for solder sealing the opening of the case 1. The lid 5 is smaller than the perimeter of the edge of the opening of the case 1 and larger than the inner perimeter. Solder fillet is formed from the perimeter of the upper edge of the case 1 toward the perimeter of the lid 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component whose element needs to be sealed in a package such as a SAW device.

[0002]

2. Description of the Related Art A conventional electronic component will be described with reference to FIG. First, a ceramic case 101 having a plating base layer formed on the upper end surface is plated, and a metal layer 100 is formed on the plating base layer. Next, the element 102 is housed in the case 101, and is covered with a metal lid 104 having a solder layer 103 formed on one surface in an opening of the case 101 so that the solder layer 103 comes to the case 101 side. The solder layer 103 was melted by heating from the upper surface of the case 104, and the case 101 was solder-sealed with the lid 104.

[0003]

According to the construction, the solder layer 1
03 may be melted, a large number of voids 105 may be generated in the solder layer 103 between the upper end surface of the case 101 and the lid 104, possibly due to generation of hydrogen gas from the plating base layer and the lid 104. There was a problem that it could not be secured sufficiently.

Accordingly, an object of the present invention is to provide an electronic component having a sufficient airtightness.

[0005]

In order to achieve this object, an electronic component according to the present invention comprises a case having an opening, an element housed in the case, and a metal layer provided on an opening end surface of the case. A lid for solder-sealing the opening of the case, wherein the lid is smaller than the outer periphery of the opening end surface of the case and larger than the inner periphery.
Since the solder fillet is formed from the outer peripheral portion of the upper end surface of the case to the outer peripheral portion of the lid, sufficient airtightness can be ensured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a case having an opening, an element housed in the case, a metal layer provided on an opening end face of the case, and A lid that seals the opening with solder; the lid is an electronic component that is smaller than the outer peripheral portion of the opening end surface of the case and larger than the inner peripheral portion, and can improve airtightness.

According to a second aspect of the present invention, there is provided the electronic component according to the first aspect, wherein the case-side end of the lid is formed in a curved shape, and a solder fillet is easily formed.

According to a third aspect of the present invention, there is provided the electronic component according to the first or second aspect, wherein the upper end surface of the case is provided with irregularities, and the concave portion is provided between the inner peripheral portion of the case and the lid. A pseudo solder fillet can be formed, and the airtightness is further improved.

According to a fourth aspect of the present invention, there is provided the electronic component according to any one of the first to third aspects, wherein a nickel layer is formed between the lid and the solder layer. At the time of sealing, generation of hydrogen gas from the lid can be prevented, that is, generation of voids can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a SAW device as an example of an electronic component.

(Embodiment 1) FIG. 1 is a cross-sectional view of a SAW device according to the present embodiment. Reference numeral 1 denotes a case having an opening composed of a ceramic substrate 1a and a ceramic frame 1b; Is a metal layer provided on the upper end surface of the case 1, 3 is a SAW element housed inside the case 1, 4 is a solder layer, 5 is a lid, and 6 is a bump.

A method for manufacturing this SAW device will be described. First, a plating base layer having the same shape as the substrate electrode 1c to be formed on the surface of the ceramic substrate 1a containing aluminum oxide as a main component is formed. This plating base layer is mainly composed of tungsten. Next, a ceramic frame 1b containing aluminum oxide as a main component is provided on the ceramic substrate 1a.

Next, a screen printing plate for forming a plating underlayer having a print pattern of the same shape as the upper end face of the ceramic frame 1b is placed so that the print pattern matches the upper end face of the ceramic frame 1b. Next, a plating base layer forming agent containing tungsten as a main component is applied on the screen printing plate, and the screen printing plate is transmitted through a squeegee and printed on the ceramic frame 1b. By this step, a plating base layer can be formed on the upper end surface of the ceramic frame 1b.

Thereafter, this is fired to form a ceramic substrate 1a.
And a case 1 in which the ceramic frame 1b is integrated.

Next, a nickel plating layer is formed on the plating base layer of the case 1, a gold plating layer is formed on the nickel plating layer, and a substrate electrode 1c and a metal layer 2 are obtained.

Further, on both sides of the input and output interdigital transducer electrodes 3a on the voltage substrate, reflectors are provided on both sides of the input and output interdigital transducer electrodes 3a and electrically connected to the input and output interdigital transducer electrodes 3a. The SAW element 3 is obtained by forming a plurality of connection electrodes 3b. Next, a plurality of conductive bumps 6 are formed on the connection electrodes 3b of the SAW element 3.

Thereafter, the bump 6 of the SAW element 3 is pressed against the substrate electrode 1c of the case 1 and the temperature, pressure and ultrasonic waves are applied from the back surface of the piezoelectric substrate to the inside of the case 1 via the bump 6 through the bumps 6.
The AW element 3 is connected and fixed.

Next, a metal lid 5 having a solder wettability and having a solder layer 4 formed on one surface is positioned with the solder layer 4 facing the case 1 such that the opening of the case 1 is sealed. The case 1 is sealed with the lid 5 by applying pressure and heat from the upper surface of the lid 5 to melt the solder layer 4.
By making the outer periphery of the lid 5 larger than the inner periphery of the case 1 and smaller than the outer periphery, a solder fillet is also formed between the side surface of the lid 5 and the case 1.

At this time, in order to prevent the solder layer 4 from being oxidized, by performing the treatment in a nitrogen atmosphere having an oxygen concentration of 100 ppm or less, preferably 5 ppm or less, good solder fluidity can be obtained, and voids are small and large. In addition, a uniform solder fillet can be formed.

Hereinafter, the solder layer 4 formed on one side of the lid 5
The points for obtaining the electronic component of the present invention having excellent airtightness without increasing the thickness of the electronic component will be described.

(1) As shown in FIG. 2, by providing a step 7 on the upper end surface of the case 1 so that the inner peripheral portion is lower, the thickness of the solder layer 4 between the case 1 and the lid 5 is increased. At the same time, a pseudo solder fillet can be formed, and the airtightness can be further improved.

(2) As shown in FIGS. 3 and 4, the lid 5 is a large-sized metal plate 5a having a solder layer 4 formed on one surface.
Is placed on a support 8 provided with a through hole for forming a lid 5 having a desired size such that the solder layer 4 is on the lower side. Next, the metal plate 5 is formed by a punching rod 9 corresponding to the through hole.
a is punched out to form a lid 5. The lid 5 thus obtained has a curved shape from the bottom surface to the side surface of the metal plate 5a on the side where the solder layer 4 is formed. Since the solder layer 4 also covers this curved end portion, the lid 5 is When soldering to the case 1, the solder easily wraps around the side surface of the lid 5, so that a large solder fillet can be formed between the outer peripheral portion of the lid 5 and the case 1. It can be carried out.

(3) As shown in FIG. 5, when the lid 5 and the case 1 are solder-sealed, the mechanism of generating hydrogen gas from the lid 5 and the plating base layer is not well understood. In the case where the nickel layer 10 is provided therebetween, the formation of voids in the solder layer 4 can be prevented, probably because the nickel layer 10 blocks the hydrogen gas generated from the lid 5.

(4) In the above embodiment, the SAW device has been described as an example. However, any electronic component whose elements need to be hermetically sealed in a case is similarly improved in hermeticity.

[0025]

As described above, according to the present invention, a solder fillet is formed between the case and the side surface of the lid, and although the mechanism is unknown, the generation of voids can be suppressed. Electronic components can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a SAW device as an electronic component according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a SAW device as an electronic component according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining a lid forming step in one embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a lid forming step in one embodiment of the present invention.

FIG. 5 is a sectional view of a SAW device as an electronic component according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional SAW device as an electronic component.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Case 1a Ceramic substrate 1b Ceramic frame 1c Substrate electrode 2 Metal layer 3 SAW element 3a Input / output interdigital transducer electrode 3b Connection electrode 4 Solder layer 5 Lid 5a Metal plate 6 Bump 10 Nickel layer

Claims (4)

[Claims] 1. A case having an opening, an element housed in the case, a metal layer provided on an opening end surface of the case, and a lid for solder-sealing the opening of the case. Is an electronic component configured to be smaller than the outer peripheral portion of the opening end face of the case and larger than the inner peripheral portion. 2. The electronic component according to claim 1, wherein the end of the lid on the case side is curved. 3. The electronic component according to claim 1, wherein an irregularity is provided on an upper end surface of the case. 4. The electronic component according to claim 1, wherein a nickel layer is formed between the lid and the solder layer.