JPS59156943A - Glass sealing method to metal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sealing metal to glass, and more particularly to manufacturing hermetically sealed electronic components.

Metal hermetically sealed to glass components is widely used in the electronics industry. Mainly, these are made by melting glass into pre-treated metal leads and electronic component bodies in an atmosphere furnace. The sealing temperature is maintained high enough to melt and flow the glass and bond it to the pretreated metal. During cooling,
A strong hermetic seal is formed between the glass and the surrounding metal. The sole must be airtight to exclude moisture and other contaminants from the internal packaging, and must be strong enough to withstand the stresses encountered during assembly, connection, and use.

For airtightness, the latest MIL standard 883B
(The leakage rate of helium is l x lO = MTM c
The high reliability of hermetically sealed electronic components depends on the integrity of the sole between the glass and the metal. In order to produce a seal consistently and reliably from beginning to end, attention must be paid to the selection of materials, several processing parameters, especially the observation of the furnace atmosphere adopted during the preliminary treatment of the metal, and the sealing of the glass to metal plate. Must.

There are mainly two types of seals used industrially: the J-matted seal and the R-compression seal. Although there are some differences in the production of these two food seals, the steps in the same order are (1) (degassing or decarburization,
(2) oxidation, and (3) sealing.

The atmosphere used in the degassing step and the sealing step is substantially the same in the compression seal method and the mated seal method, but the atmosphere used in the oxidation step is slightly different.

1. Degassing Degassing, also known as decarburization or degassing, removes all carbon or adsorbed gas from the metal to prevent bubbles from forming on the glass or at the glass-to-metal interface during sealing. matt seal and compression for the purpose of removing
Both tests are performed on the metal lead and the component body.

The degassing is generally done in a batch or continuous furnace.
It is typically carried out for 10-30 minutes at a temperature of 00 to 1100'C (1650 to 2oOo"F). The atmosphere used for degassing is typically wet hydrogen, dissociated ammonia, and exothermic gases (6% to 8% carbon monoxide). , dew point = 116°C) or a humidified hydrogen-nitrogen mixture.The atmosphere must be decarburizing without oxidizing the metal.During this process, insufficient decarburization or oxidation of the metal Inadequate decarburization or degassing, which is undesirable and adversely affects subsequent metal oxidation and glass-to-metal sealing, can result in the formation of bubbles during adhesion and loss of strength and tightness during decarburization. The oxidation of metals in
Oxide saturation of the glass can lead to poor airtightness in the final seal and problems in subsequent processing steps.

Long-standing prior art methods use readily available hydrogen, such as bottled hydrogen, dissociated ammonia, or rich exothermic gases, to obtain the high hydrogen levels necessary to prevent metal oxidation through a humid degassing atmosphere. We have used available atmosphere sources.

2. Oxidation The next step in the production of metal-glass hermetic seals is an oxidation step, the purpose of which is to create a thin layer of metal oxide arsenate on the surface of the metal leads and the component body. The oxide layer consists of a surface scale layer and a lower layer of intergranular oxide. The intergranular oxide layer promotes adhesion of the glass to the metal plate through chemical bonding. Although some oxidation takes place in the manufacture of some compression seals, the oxidation process is primarily associated with the manufacture of matted seals, and the present invention is particularly concerned with matted seals.

The metal alloy commonly used for matte soles is commercially available under the trademark Copal, and is composed mainly of iron, 3Q% Ni, and 15-18% Co.

Consists of decimal coefficient Mn and trace amounts of other elements. Copal alloys are commonly manufactured in batch or continuous furnaces using 7506
Oxidized at temperatures of ~1040°C. The time required for heating to fully oxidize the copper alloy depends somewhat on the mass of the parts in the furnace, but more importantly on the depth of oxidation required. The atmospheres previously used for the oxidation of copal alloys include exothermic gases, air and moist hydrogen-nitrogen mixtures. Many no-metics
High product rejection rates in seal plants are generally due to uncontrolled oxidation levels.

Underoxidation of copal alloys and similar metal alloys results in the formation of undesirably low strength glass-to-metal seals.

This low strength is due to the interface between the relatively thin oxide layer and the glass, which results in the formation of only weak (or superficial) chemical bonds. Pa5x (Pa5k, Jos
eph A, New Techniques 1nG
lass-to-Metal Sealing
i Proceedings of IRE.

vol, 36. Nu 2. Feb. 1948.
pp 286-289) and Zakray se
K et al. (AJ, ternative method for
r theEvaluation of Fuse
d Glass to Metal 5eal
s.

5yracuse, N, Y,; G, E, Co,,
Feb. 1979. Research conducted by (pp. 43) concluded that the properties of matted seals are determined by the amount of intergranular oxides deposited on the metal.

Overoxidation of copal alloys also has deleterious consequences.

Since the glass cannot completely penetrate the oxide layer during normal sealing, it becomes a leakage body, providing a porous continuous path through which gas can penetrate into the container.

Peroxidation also causes saturation of the glass, resulting in the formation of air bubbles during the sealing process. Pa5k and Zak-ray
sek defines the amount of oxidation desired for optimum seal strength and airtightness. Based on oxidation degree studies obtained using various atmosphere compositions and cycle times at specific temperatures, Zakraysek found that the intergranular oxide level (or depth) required for optimal strength and tightness is 2.0 ~
It was concluded that it was 6.5μ. Higher oxide levels increase seal strength, but to a limited extent,
It is desirable in that it meets Mil Spec and allows for subsequent processing such as cleaning and brazing without the problems associated with overoxidation.

From the above studies, it is deduced that the degree of oxidation at a particular temperature can be tuned by tightly controlling both the cycle time and the oxidation potential of the atmosphere. Since the furnace temperature and cycle time are usually fixed, a constant atmosphere is required to achieve consistent oxide levels no matter what metal is used.

The oxidation potential of exothermic gases and atmospheres such as air varies depending on daily fluctuations in atmospheric humidity, the nature of the natural gas used in the reaction in the exothermic gas generator, and the age and condition of the generator. resulting in variations in composition. These, among other uncontrollable variables in the furnace atmosphere, result in variations in oxide levels resulting from the oxidation of Kovar and other alloys.

3. The sealing process in the manufacturing process of sealed compression seals and matted seals is carried out at 950 to 1060'C (1
750-1950°F).

The pretreated leads and component body during the sealing process are joined by flowing molten glass to form the desired hermetic bond. The furnace atmosphere used during the sealing process is typically a lean exothermic gas or N2-based atmosphere. The selected atmosphere composition is to prevent overoxidation of the metal leads and to allow a weak oxidation condition to exist in the furnace to promote glass flow and adhesion. A typical atmosphere composition that has been used in the sealing process is an exothermic gas with an air to gas ratio of 8:1 to 3:1 or a gas composition mainly composed of N2.

The present invention has shown that in order to consistently obtain high performance glass-to-metal hermetic seals in electronic components, it is necessary to carefully control the conditions used, especially during the metal oxidation step prior to heat sealing.

The necessary conditions to be used during such an oxidation step are the depth or depth of the intergranular oxides, which consist primarily of Fe3O4.

The desired range of oxide depth is 2.0 to 10.0 microns to ensure that the oxide depth is within the desired range to provide optimal strength and tightness of the seal. Fe
Fe3O4 is the most desirable type of oxide because 3O4 can be dissolved directly into the glass without undergoing a transformation unlike Fear3, which must first be converted to Fe3O4 before melting. This conversion requires Makima, and if it is not completely converted, it will become a seal with bad properties. Although further increases in oxide depth also increase seal strength, a depth of up to about 10μ is desirable in that the product meets Mil-Spec and avoids potential problems in subsequent processing steps. The invention applies in particular to matsito seals of copal and glass. The production of the desired seal according to the present invention involves (1) degassing or decarburization, (2) oxidation (
(3) sealing.

The degassing step can be carried out in a batch or continuous furnace at the temperatures and gas atmospheres hitherto used by the prior art, provided that the furnace atmosphere ensures that no significant oxidation occurs during the degassing step. I have something to do. This is accomplished, for example, by using an atmosphere in the furnace containing 100% hydrogen and less than about 5 cm (by volume) of water.

Good degassing (decarburization) is obtained when the N2/N20 volume ratio is greater than or equal to about 100%.

Similarly, the sealing step is carried out at temperatures and conditions employed heretofore, for example at temperatures of 950 to 1060 DEG C., using an exothermic gas or a nitrogen-based atmosphere.

A key step in the treatment cycle according to the invention is that after degassing (or decarburizing) the copal (or other alloy):
This is an oxidation process performed before heat sealing copal to a glass insulator. Reliable metal-glass metal
To obtain intergranular oxides of the desired type and depth that guarantee a seal, the oxidizing atmosphere in the furnace consists of water, carbon dioxide,
The carrier gas comprises an oxidizing agent such as nitrogen oxide in an amount such that oxygen is reduced to a value such that formation of Fear3 is minimal and Fe5O4 is the main product of oxidation.

The oxidizing atmosphere in one embodiment of the invention consists of a gaseous mixture of water and carbon dioxide, which serves as the oxidizing agent and carrier gas. Such a mixture has a volume factor of about 0.
It consists of 25-99% hydrogen, about 1-99% carbon dioxide, and the balance if necessary an inert gas.

In a preferred embodiment, the oxidizing agent, such as water, has an amount (volume) of water less than or equal to about 5.0 times the amount of free hydrogen, and a water content of about 0.6 to 1 volume or 0.9. controllably added to an inert gas such as nitrogen containing a small amount of hydrogen, such as within the range of %). Under these conditions, the intergranular oxide layer forms a desirable Fe5 layer that provides good metal-glass adhesion.
O4 type is at least the main component, and metal-
With sufficient depth to ensure good bonding of the glass.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Numerous experiments were conducted in a commercial plant equipped with a full-scale continuous furnace under various gas atmospheres to produce glass-sealed metal leads on electronic components. In most of the controlled experiments aimed at optimizing oxidation conditions, the initial decarburization of the Kovar alloy was performed under conditions such that the Kovar alloy was free of oxides at the end of the decarburization process. Therefore, the decarburization step in this series of experiments was carried out at a temperature of about 1060° C. in an atmosphere of 100% hydrogen and a dew point of +(9)°C (corresponding to a water content of 4.18% by volume).

The oxidation step in a series of experiments was carried out in a continuous furnace with a temperature controller set at 0.138°C and a belt speed of 25°C.
．． The test was carried out at 4 cm for 1 minute using a furnace atmosphere consisting of 0.25% hydrogen (corresponding to a dew point of 3.3° C. and a water content of more than 0,765 volume) and the remainder nitrogen. Temperature profile in the furnace (
Graph) is shown in Table 1.

M] Table Time Temperature Time Temperature Time Temperature 0
138 59 7.75 1926 1052 13.
5 12706880.5 277 136 8.0
1926 1052 13.75 12176581.
0 334 '168 8.25 1928 105
3 15.00 8254411.5 407 208
8.5 1928 1053 15.25 7503
992.0 509 265 8.75 1927 1
053 15.50 6773582.5 699 3
7] 9.0 1924 1051 15.75 6
]83263.0 1009 543 9.25 19
20 1049 16.0 5572923.5 13
86 752 9.5 1912 10444.0 1
678 914 9.75 1904 10404.5
1790 977 10.0 1890 10325
．． 0 1846 1008 10.25 1867 1
0195.5 1890 1032 10.5 183
0 9995.75 1905 1041 10.75
1776 9696.00 1920 1049 1
1.00 1700 9276.25 1932 10
56 11.25 1616 8806.5 1938
1059 11.50 1580 8606.75
1938 1059 11.75 1564 8517
．． 0 1935 1057 12.0 1530 83
27.25 1930 1054 12.5 1450
7887.5 1928 1053 13.25 1
As can be seen from Table 1, at constant belt speed the metal underwent oxidation for about 9 minutes at temperatures ranging from about 0°C to 1060°C. Under these experimental conditions the intergranular oxide depth was in the range of 4.0-9.0μ and consisted essentially of Fe3O4.

Another series of oxidation experiments was carried out under the same conditions as the previous experiments, but with a constant hydrogen content (0.25 vol. H) and varying the amount of water added to the gaseous atmosphere of the furnace. The plotted results are shown in Figure 1 and Table 2 of the addition drawings.

+38 + 3.3 0.765 3.0
6 6.3+40 + 4.4 0.827
3.31 8.1+45 + 7.2 1.01
4.04 10.6+48 + 8.9 1.12
4.48 7.8+5(+ +10.0
1.21 4.84 111+52 +11
．． 1 1.30 5.20 11.0+55 +
12.8 1.46 5,84 16.0+
60 +15.6 1.75 7.00
17.6+67 +19.4 2.24 8.9
6 19.0+74 +23.3 2.84 11
．． 36 20.4 In another series of experiments, the rate of Co-Cool alloy passing through the oxidation furnace was varied from 5°C to 19°C.
The intergranular oxide depth was measured at various dew points ranging from This intergranular oxide consisted essentially of Fe3O4. The results are shown in Figure 2 and Table 3.

9.0 760-1060 41 5,0 7.
89.0 760-106045 7.2 9.
59.0 760-1060 51 10.6 9
．． 49.0 760-1060 55 12.8 1
6.09.0 760-1060 60 15.6
17.69.0 760-1060 67 19.4
19.07.5 760-1060 41 5.0
6.17.5 760-1060 45 7.
2 6.47.5 760-1060 51 10
．． 6'”8.87.5 760-1060 55
], 2.8 11.07.5 760-1060
59 15.0 12,76.5 760~106
0 46 7,8 4°46.5 760~10
60 50 10.0 6.66.5 760~1
060 56 13.0 7.96.5 760~
1060 59 15.0 7.36.5 760
~1060 66 18.9 6.5 The sample of the oxidized copal alloy produced in the above experiment contained 100 TiN (
104 in a furnace atmosphere with a dew point of +18.3℃).
It was sealed to glass (KimbleENJ) at a temperature of 0°C. These sealed products are manufactured using standard methods (MIL-
st, a-883'B, method 1010. Condition B) was tested and found to have acceptable hermeticity, with a helium leak rate of less than IX to -8 ATM Xc-7 seconds.

Based on the results obtained, it was determined that by oxidizing decarburized copper alloys and similar metal alloys used in the production of metal-glass matte seals for electronic components, the oxidizing agent was calculated to contain hydrogen. When carried out in a controlled furnace atmosphere where the oxidizing agent is added to an inert carrier gas containing a sufficient amount of oxidation potential to provide an adequate oxidation potential, the alloy is free from intergranular oxides of at least 2 μm. It was confirmed that precipitation always occurred at a depth of about 9 μm or less. The constant production of intergranular oxides with the abovementioned values (preferably up to a depth of about 10 microns) ensures the production of a glass-alloy seal that is good in terms of strength and tightness.

Although the invention has particular application to the production of matt seals,
It is not limited to that. For compression seals, pre-oxidation of the alloy is performed in an 82/N2/X atmosphere (where
is the necessary oxidizing agent).

[Brief explanation of the drawing]

Figure 1 is a graph showing the depth of the intergranular oxide layer formed during the oxidation of a copal alloy as a function of the dew point of the N2-H2 atmosphere in the furnace under experimental conditions using water as the oxidizing agent; The figure is a graph showing intergranular oxide depth as a function of various belt speeds and various dew points using water as the oxidizing agent. Patent Applicant Air, Products, &. Chemicals, Inc. RPC, 1 rie, z Continued from Page 1 1 - Author: Walter Francis Yext 280 East Mahanoy Street, Mahanoy City, Pennsylvania, USA 17948 Author: Kelly Leonard Berger Box 400 4 Lehighton Road, Pennsylvania 18235, United States

Claims (1)

[Claims]] Decarburizing a metal alloy in a high temperature furnace atmosphere under non-oxidizing conditions, for a period of time to consistently form an intergranular oxide layer at least 2 microns deep in the decarburized metal alloy. A glass sealing method for metal alloys for electronic components, which comprises the steps of oxidizing the metal alloy in an oxidizing furnace atmosphere under the following temperature conditions and heat-sealing the oxidized metal alloy to a glass insulating component, wherein the oxidation includes an oxidizing agent. carried out in a furnace atmosphere consisting of a carrier gas, and the furnace atmosphere further comprising Fe2O2
F'e304 is the main product of oxidation, VC.
A metal-glass sealing method characterized by comprising an amount of free hydrogen. 2. The glass sealing method for metal rie according to claim 1, wherein the atmosphere of the oxidation furnace mainly consists of an inert carrier gas. 3. The method for sealing metal plates and glass according to claim 2, wherein the oxidizing agent is water. 4. The method for sealing metal plates and glass according to claim 3, wherein the volume ratio of water to free hydrogen is about 5.0 or more and less than 1. 5. The method for sealing metal and glass according to claim 1, wherein the content of leaves in the atmosphere of the oxidation furnace is about 0.25 volumetric. 6. The oxidation is carried out in a continuous furnace in which the alloy is brought to a temperature in the range of about 760-1060° C. for about 9 minutes while moving through the furnace. The method for sealing glass with a metal plate according to item 1. 7. The atmosphere of the oxidation furnace is 2.86C (+37°F) ~
2. A method for sealing metal plates and glass according to claim 1, characterized in that the glass sealing method has a dew point of 5.5°G (+42°F). 8. The metal crow according to claim 1, characterized in that the atmosphere of the oxidation furnace consists of about 0.25% by volume hydrogen and about 0.6 to 1% by volume of nitrogen. Sealing method. 9. 2. The method for sealing metal and glass according to claim 1, wherein the alloy consists of iron as a main component and nickel and cobalt as minor components. 10, iron whose main component is the above alloy, nickel with a ratio of 4 to 30, 1
2. The method for sealing a metal plate with glass according to claim 1, characterized in that it consists of 5 to 18 Ticobalt, a decimal fraction of manganese, and trace amounts of other elements. 2. The method of claim 1, wherein the atmosphere in the oxidation furnace consists of an inert key gas containing about 0.25 volumetric hydrogen. 12. The method for sealing metal plates and glass according to claim 1, wherein the oxidizing agent is carbon dioxide. ]3. The atmosphere of the oxidation furnace is about 0.25 to 99% by volume H
2. The method for adhering a metal plate to glass according to claim 1, comprising carbon 12ide having a volume coefficient of approximately 1 to 99, and the remainder of an inert gas. ]4. A time period during which a metal alloy is decarburized in a high temperature furnace atmosphere under non-oxidizing conditions such that the decarburized metal alloy consistently forms an intergranular oxide layer with a depth in the range of 2.0-10.0 microns. In a glass sealing method for metal alloys for electronic components, which comprises the steps of oxidizing in a furnace atmosphere under and temperature conditions and heat sealing the oxidized metal alloy to a glass insulating component, the oxidation is about 0.25 volume. hydrogen and about 0.6 to 1.0
A method for sealing metal and glass, which is characterized by consisting of a volume of water and a residual amount of nitrogen.