JP2001185656A - Method for manufacturing hermetically sealed electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hermetically sealed electronic component capable of simplifying manufacturing steps, reducing its cost and manufacturing in a mass production. SOLUTION: The method for manufacturing the hermetically sealed electronic component comprises a temporarily sealing step 11 of sealing the part of a cover 4 in a package 2, a gas injecting step 12 of injecting a mixed gas in a cavity 21 from the site of the cover 4 not sealed in a mixed gas atmosphere of a first gas 17 (one type of inert gas selected from the air, N2 and an Ar) and a second gas 18 (He), a completely sealing step 14 of sealing the site of the cover not sealed in the first gas atmosphere, and a leakage hole detecting step 20 of detecting the second gas and extracting a leakage hole fault component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crystal oscillator, an IC,
The present invention relates to a hermetic electronic component in which an electronic component element such as a chip is housed in an outer case (package) and a cavity opening thereof is hermetically sealed, and a method of manufacturing the same.

[0002]

2. Description of the Related Art When an electronic component element such as a semiconductor component is exposed to the outside air, the element itself may change with time and cause a large change in characteristics. In order to prevent such abnormalities, An inexpensive gas such as N ₂ is sealed in the package, and the component element is sealed with high airtightness of about 1 × 10 ⁻⁸ atm · cc / sec to manufacture an electronic component. Further, in the subsequent steps, it is necessary to test whether or not the case was able to be sealed, and a leak hole detection test was performed assuming various leak holes.

An example of the hermetic sealing method and the leak hole detecting method will be described with reference to FIG. FIG. 5 is a cross-sectional view of a crystal resonator, which is an electronic component device in which a crystal resonator, which is one of the piezoelectric elements, is housed in a ceramic package and hermetically sealed with a metal lid.

For example, a crystal oscillator is a crystal oscillator 53,
It is mainly composed of a ceramic package 52 and a metal lid 54. The ceramic package 52 includes a plate-like ceramic layer 52a, a frame-like ceramic layer 52a.
b and 52c are laminated to form a cavity portion 521 having an open top surface as a whole. On the inner wall surface of the cavity portion 521, a step portion 522 for fixing the crystal oscillator 53 and achieving electrical connection is formed.

[0005] A sealing conductor 57 such as a seal ring is arranged around the opening of the cavity 521 of the ceramic package 52. For example, the sealing conductor 5
Numeral 7 is fixed by brazing or the like on the sealing conductor film formed around the opening of the cavity 521.

On the upper surface side of the sealing conductor 57,
A plating layer formed by a plating technique is applied. Further, the metal lid 54 for sealing the cavity 521 of the ceramic package 52 has a plating layer formed of Ni on both surfaces.

First, a quartz oscillator 53 is housed in a cavity 521 formed in the ceramic package 52 having the above-described structure. Thereafter, the metal lid 54 is placed on the sealing conductor 57 in an N ₂ atmosphere or in a vacuum,
Both are sealed by seam welding or the like. In this case, N ₂ is sealed in the inside of the crystal oscillator, or a vacuum is created.

Next, a leak hole detection test is performed. In this detection test, a method of detecting a leak hole by injecting He gas into the inside is generally performed. That is, as shown in FIG. 6, in order to inject He gas for leak hole detection, a small amount of the crystal oscillator 61 is put in the He gas injection container 63, and then the He gas is injected.
The gas injection container 63 is filled with He gas 64, and 4 to 5
Pressurize to about atmospheric pressure over 2-3 hours.

Then, the He gas 64 enters through the minute leak hole 62 in accordance with the pressure difference between the inside and outside, even if the part is airtight. Next, when put into a container 65 of a He leak detector for detecting the He gas 64, the unit for the hole through which 1 cc of gas passes per second under 1 atmospheric pressure difference is 1 atm · c.
c / sec., He can be detected from the He gas detection suction port 66 of the crystal oscillator 61 having a hole having a size of about 1 × 10 ⁻⁸ atm · cc / sec or more.

[0010]

However, the above-described test for detecting a leak hole of a crystal oscillator has a step of pressurizing the crystal oscillator itself at 4 to 5 atmospheres for 2 to 3 hours when injecting He. Therefore, not only cannot continuous production be performed, but also a container used for He injection must be prepared, which has a problem that the purchase cost is high.

On the other hand, as shown in JP-A-58-210644, a cavity 52 of a ceramic package 52 is provided.
1, the opening of the cavity 521 is sealed with a metal lid 54 in a He atmosphere, and the two are sealed by seam welding or the like, so that the cavity 521 is prepared in advance. A method of injecting He gas into the inside is disclosed.

According to this configuration, the step of pressing the electronic component itself can be omitted, and the leak hole can be detected by the He leak detector, whereby the production efficiency can be improved.

[0013] However, a problem is that a large amount of He gas, which is a tracer gas for detecting leak holes, is consumed in order to perform sealing work by filling a tank in which electronic components are disposed with He gas, thereby increasing costs. Had a point.

The present invention has been devised in view of the above problems, and the present invention provides a method for manufacturing an airtight electronic component capable of performing a leak hole detection test while minimizing He gas consumption. Is to do.

Another object of the present invention is to provide a hermetic electronic component which simplifies the process and reduces erroneous detection of the leak hole detection test without pressurizing the electronic component before performing the leak hole detection test. It is to provide a manufacturing method of.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for manufacturing an airtight electronic component in which electronic components are hermetically housed in a package. After housing the element, a temporary sealing step of sealing a part of the opening of the package with the lid, and after the temporary sealing step, one of air, N ₂ , and Ar having a humidity of 30% or less. A gas injection step of injecting the mixed gas from a portion of the package not sealing the opening under a mixed gas atmosphere of a first gas and a second gas of He; And a complete sealing step of completely sealing the unsealed opening of the package.

According to the structure of the present invention, in the complete sealing step of completely sealing the lid to the package, the lid is completely sealed in an atmosphere of one kind of inert gas selected from air, N ₂ , and Ar having a humidity of 30% or less. Is performed, the amount of He gas used in the step of detecting a leak hole can be minimized, whereby an increase in manufacturing cost can be prevented.

Further, in the gas injection step, the He gas as the second gas is set to 1 to 25% of the mixed gas.
In addition to preventing an increase in manufacturing cost, He is also used to remove He from inside the package during the subsequent temporary sealing step to complete sealing step.
Gas outflow can be suppressed, thereby preventing erroneous detection of He gas flowing out in the complete sealing step in the next leak hole detecting step. As a result, the leak hole detecting step can be performed in the complete sealing step. Can be performed continuously.
Therefore, production efficiency is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an airtight electronic component according to the present invention will be described below with reference to the drawings. Hereinafter, a description will be given using a crystal oscillator as an example of an airtight electronic component. First, the configuration of the crystal oscillator will be described.

FIG. 1 is a sectional view of a crystal oscillator, and FIG.
FIG. 3 is a diagram showing a state in which the crystal oscillator is sealed, and FIG. 3 is a diagram sequentially showing a manufacturing process of the crystal oscillator. In FIG. 1, a crystal oscillator 1 includes a ceramic package 2, a crystal oscillator 3 as an electronic component element, and a metal lid 4.
It is mainly composed of

Such a ceramic package 2 is formed by using a well-known multilayer wiring board technique. For example, the ceramic package 2 is formed by laminating a plate-shaped ceramic layer 2a and ceramic layers 2b and 2c having an opening at the center, and the opening area of the ceramic layer 2b is smaller than the opening shape of the ceramic layer 2c. It is configured. Thus, the ceramic package 2 has the cavity 21 having the upper surface opening, and the steps 22 and 23 are formed on the inner wall surface of the cavity 21 due to the difference in the opening size between the ceramic layers 2b and 2c. . Here, the step 22 is electrically connected to the electrode pad (not shown) on the bottom surface of the ceramic package 2 and an electrode pad (not shown) to which the crystal unit 3 is mechanically fixed and electrically connected. Terminal electrodes are formed.

A sealing conductor 5 is formed around the opening of the cavity 21 of the ceramic package 2, and a sealing conductor film such as 42 alloy, Kovar, phosphor bronze, etc. is deposited on the sealing conductor 5. Have been.

Such an electrode pad, terminal electrode, and sealing conductor film are formed by filling a predetermined ceramic green sheet with a conductive paste made of a high melting point metal material such as molybdenum or tungsten, and forming a predetermined shape on the sheet surface. Print conductive paste. Thereafter, the ceramic green sheets are laminated and pressed, and then fired in a predetermined atmosphere. Although the above-described forming method has been described by a method of laminating green sheets, the present invention is not limited to this, and may be formed by, for example, press molding using ceramic powder.

The quartz oscillator 3 is a rectangular quartz substrate cut along a predetermined crystal axis, excitation electrodes formed on both main surfaces of the quartz substrate, and one end of the quartz substrate from the excitation electrode. An extended lead electrode is provided.

The metal cover 4 is composed of a rectangular metal plate serving as a cover main body, and a plating layer adhered to the surface of the metal plate. For example, the metal plate has a thickness of 50 to 100 μm, and the surface plating layer has a thickness of 5 to 15 μm.
It is composed of plating.

When such a metal lid 4 is fixed on the upper surface of the ceramic package 2 and placed on the sealing conductor 5,
A part of the outer edge is dimensioned so as to be exposed from the periphery of the metal lid 4. The exposed width d of this outer edge is 50 to 3
It is desirable to expose about 00 μm. Exposure width is 50
If it is less than μm, an appropriate fillet is not formed at the end face portion of the metal lid 4, and it is difficult to visually confirm the welded state. If the exposed width exceeds 300 μm, the distance between the wall surface of the cavity 21 and the end surface of the metal lid 4 becomes small, and cracks are easily generated in the ceramic package 2.

According to the crystal oscillator 1 having the above-described structure, the cavity 21 is filled with a mixed gas of the first gas and the second gas. As the first gas, a safe and inexpensive gas, that is, one selected from air, N ₂ , and Ar is selected.
He is used as the second gas.

It should be noted that if all the gases contain a large amount of water vapor, the reliability of the crystal oscillator is greatly reduced. Therefore, the humidity of air, N ₂ and Ar is set to, for example, 30.
% Or less, more preferably 0 to 20% humidity. If the ratio exceeds 30%, the excitation electrode is contaminated and the characteristics change over time.

Next, a method for manufacturing an airtight electronic component of the present invention will be described. First, a ceramic package 2 is prepared, a conductive resin paste containing Ag is supplied to an electrode pad formed on a step portion of the cavity 21, and a lead electrode of the crystal unit 3 is connected to the electrode pad. The quartz oscillator 3 is placed on the conductive resin paste.
Then, the conductive resin paste is cured, and the crystal resonator 3 is fixed to the ceramic package 2.

Next, after adjusting the frequency of the crystal resonator 3,
The metal lid 4 is connected to the sealing conductor 5 of the ceramic package 2.
Place on top. Thereafter, the seam welder 9 shown in FIG. 2 is brought into contact with the roller head 9a around the metal lid 4 to perform welding, thereby hermetically sealing the cavity 21 in which the quartz oscillator 3 is housed. However, as shown below,
Sealing is performed in stages.

First, as the first stage, the temporary sealing chamber 11
The work is performed in (temporary sealing step). That is, the metal lid 4 is joined to the ceramic package 2 by the seam welder 9. In this case, the entire periphery of the metal lid 4 is not sealed, but a part is sealed. Therefore, the metal lid 4 which is not sealed
Is a perforated state.

Then, as a second stage, the pressure reducing chamber 12
The operation is performed in (gas injection step). That is, vacuum decompression is performed in the decompression chamber 12. At this time, the air inside the crystal oscillator 1 (the inside of the cavity 21) arranged in the decompression chamber 12 is sucked out and brought into a vacuum state. Thereafter, N2 gas and He gas for leak detection are injected into the decompression chamber 12 at a constant ratio. At this time, a mixed gas of N ₂ gas and He gas enters the inside of the crystal oscillator 1.

As a third step, the process proceeds to a sealed chamber 14 (complete sealing step) provided adjacent to the decompression chamber 12 via a boundary wall 13. When moving, the boundary wall 13 moves while opening and closing appropriately. The sealed chamber 14 is filled with the same gas as the first gas injected simultaneously with the He gas in the decompression chamber 12, for example, N ₂ gas or the like, and under the atmosphere, a part of the remaining metal lid 4 is left. Seal the hole. After that, it is moved to the auxiliary chamber 16 provided side by side through the sealed chamber 14 and the boundary wall 15. This also moves while opening and closing the boundary wall 15 appropriately. In the preliminary chamber 16, the crystal oscillator 1 is returned from the reduced pressure state to the atmospheric pressure state and taken out. As a result, the crystal oscillator 1 is completed in a state where the first gas, for example, the N ₂ gas and the He gas are injected into the internal cavity 21.

Next, immediately after the preliminary chamber 16, a step of performing a leak hole detection test using a He leak hole detector is performed.
The crystal oscillator 1 is taken out of the preparatory chamber 16 to enter the He leak detector, and He is detected after decompression in vacuum. This leak hole detection test detects only He gas,
If there is a hole through which 1 cc of gas passes per second under a pressure difference of 1 atmosphere, the unit is 1 atm · cc / sec.
This is for detecting He gas emitted from the crystal oscillator 1 having a hole having a size of about 10 ⁻⁸ atm · cc / sec or more.

The condition of the sealing performed in the temporary sealing chamber 11 may be at least as long as the metal lid is temporarily fixed to the seal ring at one or more places. However, more preferably, among the sides around the metal lid, it is preferable that three sides are completely sealed and one other side is not sealed. At that time, 0.1mm or more of one side,
At the maximum, it is better not to seal all over one side. The reason for this is that in order to keep He with a small atomic weight in a hole and leave it, it is necessary to make He hard to leak to the outside.

The proportion of He in the mixed gas injected into the decompression chamber 12 is preferably 1 to 25%, more preferably 1 to 20%. The reason is that if the ratio of He to be injected is less than 1%, it becomes difficult to detect He in the leak hole detection test which is the final step.
If the ratio of He to be injected exceeds 25%, He may leak in the complete sealing process performed in an atmosphere such as air, and if He leaks and enters the complete sealing process, Subsequently, even if a leak hole detection test of the crystal unit is performed, an erroneous determination may occur as shown in FIG. In order to avoid an erroneous determination, the test must be performed with a sufficient distance from the leak hole detection tester, and accordingly, the process and equipment must be separated.

However, if the He gas in the mixed gas is 25% or less of the whole gas, for example, even if a leak hole detector is installed immediately after the complete sealing step, erroneous determination is reduced and He gas is reduced.
It is also possible to line up a series of processes up to the leak detector, further improving production efficiency. By setting the content of the mixed gas to 1% to 20% or less, a manufacturing process in which erroneous determination is completely avoided can be achieved.

As described above, if the crystal oscillator 1 is hermetically sealed, if it is not air-tightly sealed and is exposed to the outside air, it will change with time, causing a large change in characteristics. Therefore, in order to prevent such abnormalities from occurring, 1 × 10 ⁻⁸ atm · cc / sec. A method of hermetically sealing with a high degree of hermeticity is employed.

As described above, the crystal oscillator 1 has been described as an example. In addition, other electronic components such as a semiconductor element and a capacitor are simultaneously placed and enclosed in a container such as a ceramic package to form a composite. Parts can also be formed.

[0040]

As described above, according to the method for manufacturing an airtight electronic component of the present invention, a temporary sealing step of sealing a part of the lid in a package, the first gas (air having a humidity of 30% or less,
A gas injection step of injecting a mixed gas into the cavity from a part of the lid that is not sealed under a mixed gas atmosphere of one type of inert gas selected from N ₂ and Ar) and a second gas (He). And a complete sealing step of sealing an unsealed portion of the lid in the first gas atmosphere. Therefore, in the complete sealing step of completely sealing the lid in the package, the complete sealing is performed in an atmosphere of one kind of inert gas selected from air, N ₂ , and Ar, so that the amount of He gas used is minimized. As a result, a reduction in the cost of the product, which can prevent an increase in the manufacturing cost, is realized.

Further, in the gas injection step, the He gas as the second gas is set to 1 to 20% of the whole, so that the outflow of the He gas from the inside of the cavity can be suppressed in the subsequent complete sealing step. This allows the second
Even if the leak hole detection step of detecting the gas of the above and extracting the leak hole defective product is sequentially performed, the He leaked out in the complete sealing step.
Incorrect detection of gas is prevented, so that the leak hole detection step can be performed continuously after the complete sealing step. Therefore, production efficiency, yield, and production costs can be minimized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crystal oscillator that is an airtight electronic component of the present invention.

FIG. 2 is a transparent view showing a state in which a crystal oscillator which is an airtight electronic component of the present invention is sealed.

FIG. 3 is a view for explaining a manufacturing process for sealing a crystal oscillator which is an airtight electronic component of the present invention.

FIG. 4 is a graph showing a He content rate and an erroneous determination rate of a He leak detector.

FIG. 5 is a cross-sectional view of a crystal oscillator which is a conventional hermetic electronic component.

FIG. 6 shows a crystal oscillator He as a conventional hermetic electronic component.
It is a figure which shows the state of injection | pouring and a He leak test.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator 2 ... Ceramic package 3 ... Crystal oscillator 4 ... Metal lid 5 ... Conductor for sealing (seal ring) 11 ... Temporary sealing room 12 ...・ Decompression chamber 13 ・ ・ ・ Boundary wall 14 ・ ・ ・ Sealed chamber 15 ・ ・ ・ Boundary wall 16 ・ ・ ・ Preparatory chamber 17 ・ ・ ・ N ₂ gas (first gas) 18 ・ ・ ・ He gas (second gas) gas)

Claims (2)

[Claims] 1. A method for manufacturing an airtight electronic component in which an electronic component element is hermetically housed in a package, wherein after the electronic component element is housed in the package, a part of an opening of the package is partially covered with the lid. And a mixed gas of a first gas composed of one of air, N ₂ , and Ar having a humidity of 30% or less and a second gas composed of He after the temporary sealing step. A gas injecting step of injecting the mixed gas from an unsealed portion of the package under an atmosphere; and completely sealing the unsealed opening of the package in the first gas atmosphere. A method for manufacturing an airtight electronic component, comprising: 2. The method for manufacturing an airtight electronic component according to claim 1, wherein the second gas in the gas injection step is 1% to 25% of the mixed gas.