JPH046769A - Glass terminal for electronic component - Google Patents

Abstract

PURPOSE:To obtain a glass terminal with high reliability by sealing leads to an eyelet made of a tungsten group sintered alloy having a thermal expansion coefficient near that of silicon and a good heat dissipation property with high heat resistance and airtightness via glass. CONSTITUTION:When an eyelet 10 is formed with a tungsten group sintered alloy by powder molding, thermal expansion coefficients of the eyelet 10 and a silicon semiconductor element mounted on it are matched to improve the heat dissipation property of the eyelet 10, and leads made of Kovar are airtightly sealed to the eyelet 10 via borosilicate glass by the matched seal method to obtain a glass terminal easily with no trouble. The eyelet 10 is made of a copper alloy with a thermal expansion coefficient similar to that of borosilicate glass, Kovar and silicon, and it can be formed by cut-machining a copper alloy block impregnated with copper into sintered tungsten or molybdenum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass terminal for an electronic component (hereinafter referred to as a glass terminal) on which an optical element, a semiconductor element, a hybrid circuit, etc. are mounted.

[Prior Art] As the above-mentioned glass terminal, there is conventionally a glass terminal in which a lead of a metal input/output line is hermetically sealed with glass to a metal eyelet for mounting an element, etc. .

In this glass terminal, the lead is hermetically sealed to the eyelet by a compression seal method or a matte seal method.

The two sealing methods will be explained in detail below.

In the compression seal method, the eyelet is formed from a metal with a larger coefficient of thermal expansion than glass or lead, and the glass is heated together with the eyelet to melt it, and then when it is cooled, the eyelet is sealed by the contraction force of the eyelet. This is a method in which the leads are hermetically sealed using glass.

On the other hand, the matt seal method uses materials with similar coefficients of thermal expansion for the eyelet, crow, and lead, and seals the lead to the eyelet using glass through an oxide film formed on the eyelet surface and around the lead. This is a method of sealing.

Comparing these two sealing methods, the glass terminals formed by the matt sealing method have excellent heat-resistant airtightness due to the characteristics of the manufacturing method, while the glass terminals formed by the compression sealing method have excellent heat dissipation due to the characteristics of the material used. Excellent in sex.

However, conventional glass terminals use iron or an iron-Ninocer cobalt alloy, which is an alloy whose main component is iron, for the eyelet. The terminals were unsuitable because the thermal expansion coefficients of the elements and the eyelets did not match, and the eyelets had poor heat dissipation properties.

Therefore, the eyelet is made of a glass terminal using a copper alloy made of sintered tungsten impregnated with copper, which has a thermal expansion coefficient close to that of a semiconductor element made of iron and has high thermal conductivity (Japanese Patent Application Laid-Open No. Publication No. 73648, JP-A-63
-16582) has been proposed.

This glass terminal is made by forming an iron-containing metal plating layer such as an iron plating layer or an iron-nickel alloy plating layer on the eyelet surface directly or through a barrier layer such as a nickel plating layer. By forming an oxide film on the surface of the metal plating layer using the iron contained in the lead, the lead is hermetically sealed to the eyelet via the oxide film using glass using the matte seal method.

[Problems to be Solved by the Invention] However, the above-mentioned glass terminal has almost the same heat resistance and airtightness as a glass terminal formed by a conventional compression sealing method, and is not suitable for glass terminals that require high reliability these days. The terminals were poorly adapted.

Specifically, for example, when bonding a semiconductor element to an eyelet, the glass terminal is heated to 400 to 450°C.
There were times when the glass terminal was heated back and forth, and when the glass terminal was heated to about 430°C, the airtightness of the seal between the eyelet and the glass was lost.

The reason for this is that in the above-mentioned glass terminal, the metal plating layer containing iron is directly exposed on the eyelet surface.
When forming an oxide film on the surface of the metal plating layer, Fetus or FeO, which has poor adhesion and is brittle,
This is because an oxide film containing as a main component is formed. This is because the glass is weakly sealed to the eye left via the oxide film, which has poor adhesion and is brittle.

Note that the eyelet made of the copper alloy has a coefficient of thermal expansion close to that of glass, and therefore cannot be airtightly sealed to the eyelet using glass using a lead wire compression sealing method.

The present invention was made in view of these problems, and is a glass terminal using a metal with a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, etc., for the eyelet, and a lead in the eyelet. The purpose of the present invention is to provide a glass terminal that can be sealed with high heat resistance and airtightness using glass.

[Means for Solving the Problems] For the above purpose, a first glass terminal of the present invention is a glass terminal in which a lead is hermetically sealed to an eyelet using glass. .5
An eyelet made of a first tungsten-based sintered alloy with a composition of ~12% by weight, 15-8% by weight of copper, and the rest tungsten and unavoidable impurities, and a nickel layer, a cobalt layer, or a rhodium layer on the joint surface with the glass. / Borosilicate glass is used for the glass, and iron is used for the lead.
The lead is made of a nickel-cobalt alloy (hereinafter referred to as Kovar), and is characterized by the use of a lead with an oxide film formed around it.

In the second glass terminal of the present invention, in place of the eyelet made of the first tungsten-based sintered alloy, 3.5 to 12% by weight of nickel and 1.5 to 1.5% by weight of iron are used.
The present invention is characterized in that an eyelet made of a second tungsten-based sintered alloy having a composition of 8% by weight and the remainder being tungsten and unavoidable impurities is used.

In the third glass terminal of the present invention, in place of the eyelet made of the first tungsten-based sintered alloy in the first glass terminal, 3.5 to 12% by weight of nickel and 1.5 to 1.5% by weight of iron are used.
It is characterized by the use of an eyelet made of a tertiary tungsten-based sintered alloy having a composition of 8% by weight, 3.5 to 12% by weight of molybdenum, and the remainder tungsten and unavoidable impurities.

In the fourth glass terminal of the present invention, in place of the eyelet made of the first tungsten-based sintered alloy in the first glass terminal, a copper alloy (hereinafter referred to as It is characterized by the use of eyelets made of copper alloy.

[Function] In the first, second, third, and fourth crow terminals having the above configuration, the eyelet is annealed (heated), etc., so that the cobalt layer provided on the joint surface of the eyelet with the glass is coated directly below the cobalt layer. When iron is diffused from the iron layer, a barrier layer provided directly below the iron layer prevents the underlying metal forming the eyelet from diffusing above the barrier layer. At the same time, the barrier layer
Prevents iron from diffusing and disappearing from the iron layer directly above it into the underlying metal forming the eyelet. Furthermore, since the iron layer does not contain other metals, iron can sufficiently diffuse into the cobalt layer from the iron scraps directly below it.

Then, when the eyelet is annealed and iron is diffused into the cobalt layer from the iron layer directly below it, the iron that has sufficiently diffused into the cobalt layer forms an iron alloy around the surface of the cobalt layer, and the cobalt layer A good oxide film is likely to be formed on the surface.

Therefore, when an oxide film is formed on the surface of the cobalt layer using iron diffused into the cobalt layer by placing the eyelet in a high-temperature furnace filled with wet gas, etc., it adheres to the surface of the cobalt layer. Fe, which has a strong spinel structure with good adhesion to the surface of the cobalt layer, does not form an oxide film mainly composed of Fe, 03 or FeO, which is weak and brittle, and whose main components are Fe, 04, COF e to+, etc. The desired oxide film is reliably formed. At the same time, due to the cobalt layer covering directly above the iron layer, the iron layer comes into direct contact with the wet gas, and a weak oxide film with poor adhesion mainly composed of Fe, 03, and FeO is formed on the surface of the iron layer. is prevented.

Moreover, the thermal expansion coefficients of the first, second, and third tungsten-based sintered alloys are 4.4 to 6. OX 10-”/”C, the coefficient of thermal expansion of copper alloy is 6.0-7.2X101/°C, and the coefficient of thermal expansion of borosilicate glass is about 4. 8
X 10-@/'C, and the coefficient of thermal expansion of Kovar is 4
．． 8×10−”/′C, and their thermal expansion coefficients are close to each other.

Therefore, when a lead made of Kovar is sealed to the eyelet made of the first, second, and third tungsten-based sintered alloy or copper alloy using borosilicate glass, the bonding surface of the eyelet with the glass The above-mentioned strong adhesive and strong Fe 304 formed on the surface of the cobalt layer
through an oxide film whose main components are CoFe, O, etc.
With the matt seal method, the lead is firmly and airtightly sealed to the eyelet using glass.

[Example] Next, embodiments of the present invention will be described with reference to the drawings.

1 and 2 show preferred embodiments of the first, second, third, and fourth glass terminals of the present invention, and FIG. 1 is a perspective view thereof;
FIG. 2 shows an enlarged sectional view around the lead. The embodiment shown in this figure will be described below.

In the figure, reference numeral 10 indicates an eyelet for mounting a disk-shaped element or the like. This eyelet 10 is
, a second or third tungsten-based sintered alloy, or a copper alloy.

Among these, the first, second, and third tungsten-based sintered alloys have been recently developed as structural members for electronic components, and details thereof can be found in Japanese Patent Application No. 2-19639 and Japanese Patent Application No. 1
No. 9640. As mentioned above, the thermal expansion coefficient of these tungsten-based sintered alloys is 4.2X10-
/'C, which approximates the coefficient of thermal expansion of silicon. At the same time, the thermal conductivity of these tungsten-based sintered alloys is about 0.306 cal/cm-sec-'C, which is higher than the thermal conductivity of iron, which is 0.18 cal/cm-sec.degree.

Further, these tungsten-based alloys can be formed into various shapes by powder molding.

Therefore, if the eyelet is formed using these tungsten-based sintered alloys by powder molding, it will be a highly heat-dissipating eyelet that matches the coefficient of thermal expansion between the eyelet and the semiconductor element made of silicon mounted thereon. Therefore, a glass terminal can be easily formed in which the lead made of Kovar is sealed to the eyelet with high airtightness using borosilicate glass by the matt seal method without any trouble. In addition, by performing some machining on a tungsten-based sintered alloy that has been formed into an approximately eyelet shape by powder molding, an eyelet with a complicated shape can be easily formed without any effort.

Furthermore, these tungsten-based sintered alloys have high mechanical strength, with a tensile strength of about 80 to 120 kg/mm2, and if an eyelet is formed using these tungsten-based sintered alloys, the eyelet can be made thinner. Can be made lighter.

On the other hand, the coefficient of thermal expansion of the copper alloy is also similar to that of borosilicate glass, Kovar, and silicon, as described above. At the same time, its thermal conductivity is also approximately 0.5CaI/
Cm-5eC・℃, which is higher than the thermal conductivity of iron. The eyelet made of this copper alloy can be formed by cutting a copper alloy material made by impregnating sintered tungsten or molybdenum with copper. Therefore, if the eyelet is made of this copper alloy, it will be possible to create a glass terminal with high heat dissipation that matches the coefficient of thermal expansion between the eyelet and the semiconductor element made of silicon mounted thereon. A glass terminal sealed with high airtightness can be formed using borosilicate glass using the matt seal method.

The surface of the eyelet 10 is provided with a through hole 20 for sealing a lead, which will be described later. On the surface of the eyelet 10, including the inner peripheral surface of the through hole 20, which is the bonding surface with the glass, a barrier layer 30 made of a nickel plating layer, a cobalt plating layer, a rhodium plating layer, etc., and an iron layer 40 made of an iron plating layer, Cobalt layer 50 consisting of cobalt plating layer
and are sequentially equipped. Then, iron is diffused into the cobalt layer 50 from the iron layer 40 immediately below it, and using the iron diffused into the cobalt layer 50, Fe50. ya C0F e yo a
A strong oxide film 70 with good adhesion is formed which is mainly composed of the following.

Note that the barrier layer 30, the iron layer 40, and the cobalt layer 50 may be provided on the inner peripheral surface of the through hole 20 by sputtering, CVD (vapor phase growth), etc.
It may also be an alloy layer of nickel, cobalt, or the like. In addition, on the surface of the eyelet 10 other than the inner peripheral surface of the through hole 20,
1<The rear layer 30 and the like may not be provided, and only a plating layer for corrosion resistance, element bonding, etc. may be provided.

Reference numeral 80 denotes an input/output line glue 80 made of Kovar. Around this saw 180, an oxide film 82 mainly composed of Fe3O4, CoFe, O, etc. is formed with good adhesion and strong spinel structure using iron, cobalt, etc. contained in the lead 80. ing.

The lead 80 with the oxide film 82 formed around it is inserted into the through hole 20 of the eyelet through the oxide film 70 formed on the surface of the cobalt layer 50 on the inner peripheral surface of the eyelet.
is penetrated and hermetically sealed using borosilicate glass 90 by the manotide seal method.

Below, a method for airtightly sealing the lead 80 into the through hole 20 of this eyelet using borosilicate glass 90 will be described in detail.

After the eyelets made of the first, second, and third tungsten-based sintered alloys or copper alloys are degreased, they are immersed in an etching solution to coat the surface of the eyelet 10, including the inner peripheral surface of the through hole 20, with a plating layer. etc. are activated so that they can easily adhere to each other.

Next, a barrier layer 30 made of a plating layer, an iron layer 40, and a cobalt layer 50 are sequentially formed on the surface of the eyelet 10, including the inner peripheral surface of the through hole 20, which is the bonding surface with the glass.

Next, the eyelets 1-10 are annealed (heated) in a high temperature furnace at about 900° C. for about 30 minutes to diffuse iron from the iron layer 40 into the cobalt layer 50 directly above it.

After that, the eyelet 10 is placed in a high-temperature furnace filled with wet gas, and the surface of the cobalt layer 50 in which the iron is diffused is coated with Fe3O4 or CoFeO4 having a spinel type structure.
An oxide film 70 whose main component is h or the like is formed.

Further, the lead 80 made of Kovar is degreased, treated with acid, cleaned, and then decarburized to form a base for forming an oxide film around the saw 180.

Then, the lead 80 is placed in a high-temperature furnace filled with wet gas, and Fe:+04 or Co is placed around the saw 180.
An oxide film 82 whose main components are Fe, O, etc. is formed. Note that the cone forming the lead 80 is widely used as a glass sealing material, and by appropriately adjusting the wet gas and the temperature in the high temperature furnace, the oxide film 82 can be formed around the saw 180. It is easy to form.

Further, a ring-shaped tablet (not shown) is formed by temporarily sintering borosilicate glass that can be fitted into the through hole 20 of the eyelet. The tablet is fitted into the through hole 20 of the eyelet, and the lead 80 is inserted inside the tablet. Then, both of them were heated for about 15 minutes in a neutral gas atmosphere in a high-temperature furnace at about 1000℃.
The tablets are heated for 1 minute to melt them and then cooled.

In that case, eyelet 10, tablet, Riichido 80
are placed in a carbon jig (not shown) for assembling glass terminals, and are positioned and supported so that they do not move.

Then, the lead 80 is hermetically sealed in the through hole 20 of the eyelet using a borosilicate glass 90 by a matte seal method.

The first, second, third, and fourth glass terminals of the present invention shown in FIGS. 1 and 2 are constructed as described above.

Next, a comparative experimental example of airtightness between the first, second, third, and fourth glass terminals of the present invention and a conventional glass terminal will be described.

In the first, second, third, and fourth glass terminals of the present invention, the inner circumferential surface of the through hole corresponding to the bonding surface with the glass of the first, second, and third eyelet made of the tungsten-based sintered alloy or copper alloy. A barrier layer of about 2 μm thick made of a nickel plating layer, an iron layer of about 2 μm thick made of an iron plating layer, and a cobalt layer of about 2 μm thick made of a cobalt plating layer are sequentially provided on the cobalt layer. Using iron diffused from the iron layer immediately below, an oxide film containing Fe 304, CoFe, O, etc. as main components and having a spinel structure was formed on the surface of the cobalt layer. In addition, in the conventional glass terminal C1, the inner peripheral surface of the through hole, which is the joint surface with the glass of the eyelet formed of a copper alloy made by impregnating sintered tungsten with copper, is coated with a thick iron-nickel alloy plating layer. Sa4
A μm thick metal plating layer was formed, and iron contained in the metal plating layer was used to form an oxide film on the surface of the metal plating layer.

In both the first, second, third, and fourth glass terminals of the present invention and the conventional glass terminal, Kovar is formed in the through hole of the eyelet through the oxide film formed on the inner peripheral surface of the hole. A lead having an oxide film formed around it was hermetically sealed using borosilicate glass by a matte seal method. When we investigated its airtightness, we found the results shown in Table 1 below.

Table 1 The airtightness test in Table 1 was conducted by sequentially applying the heating temperatures listed in the table to the first, second, third, and fourth glass terminals of the present invention and the conventional glass terminals for the heating times listed in the table. It shows whether the airtightness of each glass terminal is good or bad when added to the glass terminal.

According to this Table 1, the first, second, third, fourth
It can be seen that the glass terminal maintains its airtightness better than conventional glass terminals even when heated to high temperatures.

Also, according to experiments, if the barrier layer 30 such as a nickel plating layer has a thickness of about 2 to 4 μm, the base metal forming the eyelet 10 will be formed on the iron layer 40 or the cobalt layer 50 above the barrier layer 30. It was confirmed that there was no adverse effect on the airtightness of the glass terminal due to diffusion. In addition, the iron layer 40
Fe with a spinel structure on the surface of the cobalt layer 50
304 and C.

It plays an important role in forming the oxide film 70 mainly composed of F e to 4, etc., and its thickness is about 2 to 4 μm.
If so, it was confirmed that the oxide film 70 was accurately formed on the surface of the cobalt layer 50. In addition, the cobalt layer 5
The thickness of 0 is closely related to the annealing time, and if the thickness is about 1 to 3 μm, the oxide film 70 mainly composed of FezO<, CoFe, 04, etc. can be accurately formed on the surface of the cobalt layer 50. or thicker,
It was confirmed that the amount of iron diffused around the surface of the cobalt layer 50 decreased, making it difficult to form the oxide film 70 accurately on the surface of the cobalt layer 50.

The first, second, third, and fourth glass terminals of the present invention include, in addition to the solid type glass terminal in which the eyelet 10 is in the shape of a disk, as shown in FIG. It can also be used for can-type glass terminals, or rectangular glass terminals with a metal peripheral wall that accommodate hybrid circuits, semiconductor elements, etc.

[Effects of the Invention] As explained above, the first, second, third, and fourth effects of the present invention
According to the glass terminal, it is suitable for mounting recent highly integrated semiconductor devices, etc., and has a coefficient of thermal expansion similar to that of the glass terminals that form the devices, and has good heat dissipation properties. 1. 2. 3. A highly reliable glass terminal in which the lead is sealed to an eyelet made of tungsten-based sintered alloy or copper alloy using glass to provide high heat-resistant airtightness. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of first, second, third, and fourth glass terminals for electronic components of the present invention, and FIG. 2 is an enlarged sectional view of the vicinity of the leads of the glass terminal of FIG. 1. 10...eyelet, 20...through hole, 30...
Barrier layer, 40... Iron layer, 50...-Cobalt layer, 7
0... Oxide film, 80... Lead, 82... Oxide film, 90... Borosilicate glass. Patent applicant Shinko Electric Industry Co., Ltd.

Claims (1)

[Claims] 1. A glass terminal in which a lead is hermetically sealed to an eyelet using glass, wherein the eyelet contains 3.5 to 12% by weight of nickel, 1.5 to 8% by weight of copper, and the remainder. is an eyelet made of a first tungsten-based sintered alloy with a composition of tungsten and unavoidable impurities, and a barrier layer such as a nickel layer, a cobalt layer, or a rhodium layer, an iron layer, and a cobalt layer are sequentially formed on the joint surface with the glass. In order to prepare the cobalt layer, iron diffused from the iron layer immediately below it is used, an eyelet with an oxide film formed on the surface of the cobalt layer is used, the glass is made of borosilicate glass, and the lead is made of iron-nickel. - A glass terminal for an electronic component, characterized by using a lead made of a cobalt alloy and having an oxide film formed around the lead. 2. In the glass terminal for electronic components according to claim 1, in place of the eyelet made of the first tungsten-based sintered alloy, 3.5 to 12% by weight of nickel, 1.5 to 8% by weight of iron,
A glass terminal for an electronic component, characterized in that an eyelet is made of a second tungsten-based sintered alloy in which the remainder is tungsten and unavoidable impurities. 3. In the glass terminal for electronic components according to claim 1, in place of the eyelet made of the first tungsten-based sintered alloy, 3.5 to 12% by weight of nickel, 1.5 to 8% by weight of iron,
A glass terminal for an electronic component, characterized in that it uses an eyelet made of a tertiary tungsten-based sintered alloy having a composition of 3.5 to 12% by weight of molybdenum and the remainder tungsten and unavoidable impurities. 4. In the glass terminal for electronic components according to claim 1, an eyelet made of a copper alloy made of sintered tungsten or molybdenum impregnated with copper is used instead of the eyelet made of the first tungsten-based sintered alloy. A glass terminal for electronic components featuring: