JP2001015188A - Airtight terminal and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an airtight terminal equipped with a brazing filler metal free of Pb which has a comparatively high fusing point and is not fused by heating at the time of reflow of a brazing filler metal free of substitute Pb of Sn-Pb eutectic solder. SOLUTION: An Au layer 4 turned to a brazing filler metal alloyed with a Sn layer by heating is formed at the tip part of a lead 3, and the Sn layer 5 is formed on the exposed parts of a metallic outer ring 1 and the lead 3. The Au layer 4 is formed by electroless Au plating, and its thickness is set in accordance with the composition of a brazing filler metal of a Sn-Au alloy on target. For example, if a brazing filler metal of a Sn-30% Au alloy is targeted, the Au layer 4 is formed so as to have a thickness of about 1.5-2.5 μm, and the Sn layer 5 is formed so as to have a thickness of about 7.5-8.5 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic terminal and a method for manufacturing the same, and more particularly, to a lead-free (less) laminate of dissimilar metal layers to be a brazing material having a relatively high liquidus temperature. The present invention relates to an airtight terminal having the same and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, brazing has been performed in various fields, and tin (Sn) and lead (Pb) are used as brazing materials.
(Hereinafter referred to as Sn-Pb eutectic solder) is best known. This Sn-Pb eutectic solder is Sn6
It has a composition of 1.9 wt% and Pb 38.1 wt%, and has a eutectic point melting temperature of 183 ° C. Also, this Sn
In the brazing of electronic components using Pb eutectic solder as reflow solder, the reflow temperature may cause the brazing material of the brazing portion of the electronic device inside the electronic component to melt and the electronic device to fall off. No. Therefore, as a brazing material for a brazing portion of an electronic element inside an electronic component, for example, Pb 90-99 wt%-
A Pb-Sn alloy having a composition of Sn1 to 10 wt% is used. This high temperature solder has a liquidus temperature of 320 ° C,
The solidus temperature is 310 ° C.

FIG. 13 is a sectional view of a press-fit type crystal unit F as an example of an electronic component using the above-mentioned high-temperature solder. In FIG. 13, reference numeral 40 denotes a hermetic terminal, which is a metal outer ring 41.
Leads 43, 43 are hermetically sealed via a glass 42. On the exposed portions of the metal outer ring 41 and the leads 43, 43, the high-temperature solders 44, 44 are formed by plating or other methods. And the lead 4
By using the high-temperature solder 44 at the tip of 3, 43,
Electrodes 46 and 47 of crystal vibrating piece 45 are brazed. Further, the hermetic terminal 40 to which the crystal vibrating piece 45 is assembled is press-fitted and sealed in a metal cap 48 to form a press-fit type crystal vibrator F.

[0004]

However, recently, Pb
The harmfulness of the environment has been highlighted, due to environmental issues,
There is a movement to regulate the use of Pb in various countries, and there is a movement in the electronic component industry in Japan to restrict the use of Pb, which is a harmful substance. For this reason, an alternative solder called Pb-free (or Pb-less) has been developed and studied. Such Pb
Free alternative solders are being developed and studied exclusively as alternatives to Sn-Pb eutectic solders, and those with a melting point as close as possible to the melting temperature of the eutectic point of Sn-Pb eutectic solder of 183 ° C are required. Therefore, Sn-Ag and Sn-Bi systems have become the mainstream of development.

In the brazing of electronic components to a printed circuit board or the like using the solder instead of the Sn-Pb eutectic solder as the reflow solder, the brazing material of the brazing portion of the electronic element inside the electronic component is melted at the reflow temperature. The electronic element must not fall off. Therefore, as a brazing material for the brazing part of the electronic element inside the electronic component,
A high melting point alternative solder that does not melt at the reflow temperature is required.

As a Pb-free high-temperature solder that can withstand the above-mentioned reflow temperature, it is necessary to satisfy the following characteristics. Brazing is possible by melting. (Brazing property) This is a basic required characteristic as a brazing material. Do not melt at reflow temperature. (High melting point) This is an expected basic required characteristic as a Pb-free brazing material that can withstand the reflow temperature. Post-processing is possible. (Post-Workability) This is a required characteristic that the brazing material does not break even when bending a lead wire plated with a brazing material, for example. There must be bonding reliability with the substrate. (Joint Reliability) This is a characteristic required not only for the bondability to a substrate widely used in the world but also for its reliability. Post silver plating is possible. (Plating property) This is a requirement for securing the deposition property and fixation property of silver plating when finish silver plating is performed in terms of gloss and aesthetics of the surface while the surface of the brazing material is exposed. It is a characteristic.

[0007] As a Pb-free alternative solder, a solder made of an alloy of Au, Ag, Cu or the like containing Sn as a main component has been proposed. However, when an attempt is made to electrochemically form a brazing material made of an alloy of a noble metal such as Au or Ag and a relatively low-grade metal such as Sn by a wet plating method or the like, the electrode potential between the metals is reduced. The difference is so large that it is difficult to eutect. Further, even if eutectoid itself is possible, it is difficult to secure a desired composition and film thickness due to the influence of fluctuations in the concentration of components such as metal ions, hydrogen ions, and organic substances in the plating solution. There was a problem. Accordingly, an object of the present invention is to provide a hermetic terminal including a laminate of dissimilar metal layers serving as a Pb-free brazing material having a relatively high melting point that satisfies the above various required characteristics, and a method of manufacturing the same. .

[0008]

The hermetic terminal of the present invention is a hermetic terminal in which a lead is hermetically sealed via a glass to a metal outer ring. The airtight terminal is characterized in that the metal layer is laminated so that the noble metal layer is only a small portion necessary for brazing.

In the method for manufacturing a hermetic terminal according to the present invention, the tip of the lead is alloyed by heating to form a brazing material.
a step of forming a first metal layer made of any one of u, Ag, and Cu or an alloy thereof; a step of hermetically sealing the lead in a metal outer ring via glass; Forming a second metal layer made of Sn or an alloy thereof on the entire surface.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
In a hermetic terminal in which a lead is hermetically sealed to a metal outer ring via glass, a different kind of metal layer which is alloyed with the lead by heating to become a brazing material is replaced with a small metal layer which is noble metal layer necessary for brazing. An airtight terminal characterized by being formed in a laminated manner so as to include only a portion. In this way, by forming different kinds of metal layers, which are alloyed by heating into a brazing material, such that the noble metal layer is only a small portion necessary for brazing, the brazing material in the form of an alloy is formed. Even if it is difficult to form, it is possible not only to easily form and braze a brazing material having a desired composition, but also to reduce the amount of noble metal used.

According to a second aspect of the present invention, one of the different kinds of metal layers which are alloyed by heating and become a brazing material is A
The hermetic terminal according to claim 1, wherein the hermetic terminal is any one of g, Au, and Cu or an alloy layer thereof, and the other metal layer is Sn or an alloy layer thereof. A
g, Au, Cu, and Sn are each easily formed as a single layer, and are easily heated to form a binary alloy or a ternary alloy of Sn—Ag alloy, Sn—Au alloy, or Sn—Cu alloy. A brazing material made of an alloy can be formed.

According to a third aspect of the present invention, one of the different kinds of metal layers which are alloyed by heating to form a brazing material is:
The lower metal layer is a first metal layer made of any one of Ag, Au, and Cu or an alloy thereof, and the other metal layer is a second metal layer made of an upper Sn or an alloy thereof. An airtight terminal according to claim 1 or 2.
As described above, by forming the first metal layer made of any one of Ag, Au, and Cu or an alloy thereof as the lower layer, and forming the second metal layer made of Sn or its alloy as the upper layer, The first metal layer, which is relatively expensive, can be formed only on a necessary portion, and the cost can be reduced.

According to a fourth aspect of the present invention, Au, A which becomes a brazing material by being alloyed by heating at the tip of the lead.
a step of forming a first metal layer made of any one of g or Cu or an alloy thereof, a step of hermetically sealing this lead in a metal outer ring via glass, and a step of Forming a second metal layer made of Sn or an alloy thereof. As described above, the relatively expensive first metal layer is formed only on the tip of the lead, and the lead is hermetically sealed to the outer metal ring via glass. By forming two metal layers,
The cost can be reduced by reducing the amount of use of the relatively expensive first metal layer, and the relatively inexpensive second metal layer can be easily and efficiently formed by plating the entire surface at a low manufacturing cost.

The invention according to claim 5 of the present invention is characterized in that the first
The method according to claim 4, wherein the metal layer is formed by partial plating, and the second metal layer is formed by barrel plating. An expensive first metal layer is formed with partial plating to reduce the amount of relatively expensive material used to reduce cost, and a relatively inexpensive second metal layer is formed entirely by barrel plating at low plating cost. It can be easily formed.

The invention according to claim 6 of the present invention is characterized in that the first
The thickness of each of the metal layer and the second metal layer is adjusted according to the composition of the brazing material formed by alloying by heating.
The method according to claim 4 or 5, wherein the thickness of the metal layer is set smaller than the thickness of the second metal layer. By setting the thicknesses of the first metal layer and the second metal layer as described above, a brazing material having a target composition can be easily obtained.

The invention according to claim 7 of the present invention is characterized in that the first
7. The method according to claim 4, wherein the thickness of the metal layer is 1 to 7 [mu] m, and the thickness of the second metal layer is 3 to 10 [mu] m. By setting the thicknesses of the first and second metal layers as described above, a brazing material having a desired composition can be easily obtained.

The invention according to claim 8 of the present invention is characterized in that a metal layer different from the first metal layer and the second metal layer of the lead is formed on the outer metal ring, and the metal layer is connected to the lead via glass. 8. The method for manufacturing a hermetic terminal according to claim 4, wherein the hermetic sealing is performed. By forming such a metal layer on the outer metal ring and sealing it with glass, it is possible to impart functions such as rust prevention and / or solderability to the outer metal ring. The layer can be formed exclusively from the viewpoint of the brazing material, and in some cases, the second metal layer can be formed by lamination only on the tip portion of the lead.

The invention according to claim 9 of the present invention is characterized in that the hermetic terminal is a hermetic terminal for a piezoelectric device for connecting and fixing a piezoelectric device element. It is a manufacturing method. According to the above method, a piezoelectric device element such as a crystal resonator element or a surface acoustic wave element can be brazed to the airtight terminal with a brazing material having a desired composition.

[0019]

Embodiment 1 A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a hermetic terminal A for a press-fit type crystal unit which is an embodiment of the hermetic terminal of the present invention. In the figure, reference numeral 1 denotes a cylindrical metal outer ring, in which two leads 3 and 3 are hermetically sealed via a glass 2. The metal outer ring 1 is made of, for example, low-carbon steel or Fe-
It is made of a Ni alloy or an Fe-Ni-Co alloy and has an outer diameter of 1 to 3 mm. The glass 2 is made of soda lime glass, soda barium glass, borosilicate glass, or the like. The leads 3 and 3 are made of Fe—Ni alloy or F
made of e-Ni-Co alloy or the like, having an outer diameter of 0.15
0.3 mm.

FIG. 2 is an enlarged sectional view of the hermetic terminal A,
FIG. 1 is a cross-sectional view as seen from an angle different by 90 ° in a horizontal plane. Heat is applied to the tips of the leads 3 and 3 by heating, as described below.
An Au layer 4 which is to be alloyed with the n layer and becomes a brazing material is formed, and an Sn layer 5 is formed on the exposed portions of the outer metal ring 1 and the leads 3. The Au layer 4 is formed by electroless Au plating, and its thickness is set in accordance with the composition of the intended brazing material made of a Sn-Au alloy. For example, S
When aiming at a brazing material made of an n-30 at% Au alloy, the thickness of the Au layer 4 is formed to about 1.5 to 2.5 μm, and the thickness of the Sn layer 5 is about 7.5 to 8.5 μm. Formed.

FIG. 3 shows an Au layer 4 at the tips of the leads 3 and 3.
FIG. 3 is a cross-sectional view illustrating an example of a partial plating apparatus for forming a substrate.
In FIG. 3, reference numeral 30 denotes a plating tank having a high outer tank 31 and a low inner tank 32, and a gutter 33 formed between the outer tank 31 and the inner tank 32. Is set so as to match a desired plating dimension at the tip of the lead 3,3. Numeral 34 denotes an electroless Au plating solution contained in the inner tank 32, and the electroless Au plating solution 34 overflowing from the inner tank 32 passes through the gutter 33 between the outer tank 31 and the inner tank 32 to the filter 35 and the pump 36. , And is supplied to the inner tank 32 again. And the above-mentioned inner tank 3
The lead 3, 3 is vertically immersed in the electroless Au plating solution 34 of FIG.
The Au layer 4 is formed by performing u plating.

FIG. 4 shows a lead jig made of graphite together with the outer metal ring 1 and the glass tablet 2a, together with the metal outer ring 1 and the glass tablet 2a. It is sectional drawing which shows the state before sealing assembled by 37, 38. In this state, the glass tablet 2a is passed through a sealing furnace in a nitrogen atmosphere and heated at 980 to 1020 ° C. for about 5 to 10 minutes, and as shown in FIG.
Melts and leads 3 to the metal outer ring 1 through the glass 2.
An airtight terminal 3 is obtained. Since the melting point of the Au layer 4 is higher than the glass sealing temperature, the Au layer 4 does not melt or deteriorate during glass sealing.

Next, the above-mentioned many hermetic terminals are accommodated in a barrel (not shown), immersed in a Sn plating solution, and rotated by rotating the barrel, as shown in FIG. 2 and FIG. The thickness of the metal outer ring 1 and the entire surface of the leads 3 and 7 are 7 to
A 9 μm Sn layer 5 is formed. That is, the Au layer 4
The Au layers 4 are formed at the tips of the leads 3 and 3 where
The Sn layer 5 is formed by laminating the
The airtight terminal A as shown in FIG. 2 in which only the Sn layer 5 is formed on the other part and the metal outer ring 1 is obtained.

Next, a brazing method using the hermetic terminal A of the present invention will be described. FIG. 7A shows a rectangular shape as an example of an electronic element, which is another member to be brazed, to the tips of the leads 3, 3 of the hermetic terminal A, on which the Au layer 4 and the Sn layer 5 are laminated. FIG. 4 is an enlarged cross-sectional view of a main part in a state before brazing in which the quartz-crystal vibrating piece 6 is brought into contact. The crystal vibrating piece 6 is formed by forming electrodes 61 and 62 on both surfaces of a crystal piece 60. Then, the electrodes 61 and 62 are brought into contact with the Sn layer 5 formed on the leads 3 and 3, and at least the Sn layer 5 is melted by a local heating method of irradiating a laser or hot air to the vicinity of the contact portion. 23
Heat at a temperature of 2 ° C. or higher, for example, 450 ° C. here,
The reason for adopting the local heating method of irradiating a laser or hot air is that the vibration characteristics of the crystal vibrating piece 6 are liable to fluctuate due to heating, so that the heating of the crystal vibrating piece 6 is suppressed as much as possible to prevent the characteristic fluctuation. It is. Then, as shown in FIG. 7B, the Sn layer 5 formed on the tips of the leads 3 and 3 is formed.
Is melted, Au of the Au layer 4 dissolves into the liquid phase of the Sn layer 5, and a brazing material 7 made of a Sn—Au binary alloy starts to be formed at the interface between the Sn layer 5 and the Au layer 4. When heating is further continued, as shown in FIG. 7 (c), the Au in the molten Sn layer 5 reaches a concentration within the solid solution limit at that temperature.
Dissolves, and a brazing material layer 7 made of a Sn-Au binary alloy having a predetermined thickness is formed.

That is, as is clear from the phase diagram of the Au—Sn binary alloy in FIG. 8, the solid solubility limit of Au in the brazing material 7 made of the Sn—Au binary alloy changes depending on the heating temperature. The heating temperature may be set according to the desired composition of the brazing material 7. For example, if the desired composition of the brazing material after joining is to be a brazing material 7 made of a Sn—Au binary alloy of 20 at% Au, the heating temperature is set at about 280 ° C. to obtain the desired composition. Material 7 is obtained. Next, when the whole is cooled to solidify the brazing material 7,
By this brazing material 7, the electrodes 61 and 62 of the crystal vibrating reed 6 are electrically connected to the leads 3 and 3 and mechanically fixed to the quartz vibrating reed assembly. In the above description, for simplicity of explanation, the electrode 6
The alloying of the electrodes 61 and 62 with the Sn layer 5 and the Au layer 4 is not described, but alloying of the electrodes 61 and 62 with the Sn layer 5 and the Au layer 4 may occur depending on the material of the electrodes 61 and 62. In such a case, it is necessary to set not only the material of the electrodes 61 and 62 but also the thickness thereof according to the composition of the final brazing material. This is the same in each of the following embodiments.

[0026]

Embodiment 2 FIG. 9A is an enlarged sectional view of a main part of a hermetic terminal B according to a second embodiment of the present invention. That is, the hermetic terminal B of the present embodiment has a thickness of 2 to 4 as a metal layer which is alloyed by heating and becomes a brazing material only at the tips of the leads 3 and 3.
After forming the Cu layer 8 of μm and sealing the leads 3 and 3 to the metal outer ring (1) through the glass (2), the entire thickness of the metal outer ring (1) and the leads 3 and 3 is formed. 3-10μ
This is one in which an Sn layer 9 of m is formed. The melting point of the Cu layer 8 is higher than the glass sealing temperature.
The u layer 8 does not melt or deteriorate. FIG.
(A) shows the quartz vibrating reed 6 on the Sn layer 9 of the hermetic terminal B.
The state before brazing in which the electrodes 61 and 62 are brought into contact is also shown. Also in the second embodiment, the Sn layer 9 which is alloyed by heating and becomes a brazing material is formed by the liquidus temperature of 2%.
Heat to a temperature higher than 32 ° C, for example 280 ° C. Then, as shown in FIG. 9B, the Sn layer 9 is melted, and the Cu of the Cu layer 8 dissolves into its liquid phase, and the Sn—C
A brazing material 10 made of a u-binary alloy starts to be formed. When Cu is melted to the solid solution limit under the heating temperature and then cooled, as shown in FIG. 9C, the brazing material 10 made of a Sn—Cu binary alloy is used to attach the quartz vibrating piece 6 to the leads 3 and 3. Can be obtained.

[0027]

Third Embodiment FIG. 10A is an enlarged sectional view of a main part of a hermetic terminal C according to a third embodiment of the present invention. That is, the hermetic terminal C of this embodiment has a thickness of 3 to 3 as a metal layer which is alloyed by heating and becomes a brazing material only at the tips of the leads 3 and 3.
After a 7 μm Ag layer 11 is formed, the leads 3 and 3 are hermetically sealed to the outer metal ring (1) via glass (2).
The thickness of the metal outer ring (1) and the lead (3, 3) is 3
It is formed by laminating Sn layers 12 each having a thickness of 10 μm to 10 μm. Since the melting point of the Ag layer 11 is 961 ° C.,
For example, it is necessary to lower the melting point by a composition containing fluorine or the like so that the Ag layer 12 does not melt at the sealing temperature. FIG. 10A also shows a state before the brazing in which the crystal vibrating piece 6 is brought into contact with the Sn layer 12 of the hermetic terminal C. Also in the third embodiment, the Sn layer 12 which is alloyed by heating to become a brazing material is heated to a temperature higher than its melting point of 232 ° C., for example, 450 ° C. Then, as shown in FIG. 10B, the Sn layer 12 melts, and the Ag of the Ag layer 11 melts into the liquid phase thereof, and the brazing material 13 made of the Sn—Ag binary alloy starts to be formed. When Au is melted to the solid solution limit under the heating temperature and then cooled, as shown in FIG.
With the brazing material 13 made of the Sn-Ag binary alloy, an assembly structure in which the crystal resonator element 6 is connected and fixed to the leads 3 and 3 is obtained.

[0028]

Fourth Embodiment FIG. 11A is an enlarged sectional view of a main part of a hermetic terminal D according to a fourth embodiment of the present invention. That is, the hermetic terminal D of the present embodiment has a thickness of 2 to 2 as a metal layer which is alloyed by heating and becomes a brazing material only at the tips of the leads 3 and 3.
After forming a 7 μm Au layer 14, the leads 3, 3 are hermetically sealed to the metal outer ring (1) via glass (2), and then the entire surface of the metal outer ring (1) and the leads 3, 3. Sn-0.2 at% Cu having a eutectic composition with a thickness of 2 to 10 μm
Is formed on the Sn—Cu layer 15. FIG.
FIG. 2A also shows a state in which the electrodes 61 and 62 of the crystal vibrating piece 6 are in contact with the leads 3 and 3 of the hermetic terminal D. Also in the fourth embodiment, the Sn—Cu layer 15 which is alloyed by heating to form a brazing material is formed by melting the Sn—Cu layer 15 having a melting point of 22%.
Heat to a temperature higher than 7 ° C, for example 280 ° C. Then, as shown in FIG. 11 (b), the Sn—Cu layer 15 melts, and the Au of the Au layer 15 dissolves into its liquid phase, and the brazing material 16 made of a Sn—Cu—Au ternary alloy is formed. Begins to form. When Au is melted to the solid solution limit under the heating temperature and then cooled, as shown in FIG. 11 (c), the quartz crystal vibrates to the leads 3 and 3 by the brazing material 16 made of a Sn-Cu-Au ternary alloy. An assembled structure to which the pieces 6 are connected and fixed is obtained.

[0029]

Embodiment 5 FIGS. 12 (a) and 12 (b) are a plan view and a cross-sectional view of an airtight terminal E for surface acoustic waves according to another embodiment of the present invention.
FIG. 2 shows a cross-sectional view along the X-ray. The hermetic terminal E has a rectangular outer metal ring 17 and has through holes 18 at four corners, and leads 20 are hermetically sealed to the respective through holes 18 via glass 19. Then, as shown in the enlarged sectional view of the main part inside the circle, the entire surface of the metal outer ring 17 has a thickness of 2 to 4 μm for sealing and / or solderability before sealing.
An Ni layer 21 having a thickness of 2 to 7 μm is formed as an example of a metal layer which is alloyed by heating and becomes a brazing material only at the tip of the lead 20.
After the metal outer ring 17 and the lead 20 are hermetically sealed via the glass 19, the thickness of an example of a metal layer which becomes a brazing material by being alloyed with the Au layer 22 over the entire surface of the lead 20 is reduced. The Sn layer 23 of 2 to 10 μm is formed. In Example 5, the Sn layer 23 is heated to a temperature higher than 232 ° C., for example, 450 ° C., which is the melting point of the Sn layer 23 which is alloyed by heating to become a brazing material. Then, the Sn layer 23
Is melted, and the Au of the Au layer 22 dissolves into the liquid phase, and a brazing material made of a Sn—Au binary alloy (not shown)
Begins to form. When Au is melted to the solid solution limit under the heating temperature and then cooled, the leads 20, 20 are cooled.
A hermetic terminal having a brazing material made of a Sn-Au binary alloy at the tip of is obtained.

Next, the following table shows the evaluation results for each evaluation item in each of the above embodiments.

[Table 1]

The hermetic terminal of the present invention has the Sn
A relatively expensive first metal layer among different types of metal layers serving as a brazing material made of a binary alloy or a ternary alloy or more of any of Au, Sn-Cu, Sn-Ag, and Sn-Cu-Au; Since it has a second metal layer which is alloyed with the first metal layer by heating and becomes a brazing material over the entire surface of the metal outer ring and the exposed portion of the lead, By heating at a temperature equal to or higher than the low liquidus temperature of the metal layers, the two metal layers can be alloyed to form a brazing material. By heating at a temperature equal to or higher than the liquidus of at least one metal layer in a state where the electrodes of the piezoelectric device element, which are members of the piezoelectric device, are in contact with each other, the dissimilar metal layers are alloyed, and the piezoelectric device is connected to the lead of the hermetic terminal. Can braze elements etc. . In addition to the case where both metal layers are completely melted and brazed with an alloyed brazing material, the temperature at which the solid phase still remains, that is, the solidus temperature and liquidus temperature of both metal layers By heating at an arbitrary temperature in between and solidifying and cooling in a state where the solid phase and liquid phase are mixed, brazing is completed with brazing material alloyed to the solid solution limit under the heating temperature. Is also good.
According to such a brazing method, the brazing temperature can be set lower than the brazing method in which the brazing material is completely melted by heating at a temperature equal to or higher than the liquidus temperature. Not only is the cost lower, but the maintenance cost is lower, and by setting the brazing temperature to an arbitrary temperature between the solidus temperature and the liquidus temperature, the solid solution limit at the heating temperature can be reduced. There is an advantage that a brazing material having an arbitrary composition can be easily obtained.

Although the above embodiment of the present invention has been described with respect to a specific hermetic terminal and a combination of specific metal layers as a heterogeneous metal layer which is alloyed by heating and becomes a brazing material, the present invention is not limited to the above embodiment. It is needless to say that the present invention is not limited to the examples, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, as the hermetic terminals, hermetic terminals A to D for a press-fit type quartz vibrator having a metal outer ring having a right cylindrical shape, and resistance welding having a flat metal outer ring have a flat shape. Type or cold pressure contact type airtight terminal for surface acoustic wave E
However, if necessary, the shape of the metal outer ring 1 is formed on an inclined surface such that the diameter decreases toward the upper part from the middle part of the height dimension toward the upper part, and the lower part extends from the middle part. A press-fit type airtight terminal formed in a right cylindrical shape may be used. According to such a shape, there is an advantage that the initial insertion operation and the press-in operation of the metal outer ring into the metal cap become easy and smooth.

In addition, the present invention can be similarly applied to a hermetic terminal for a resistance welding sealing type or a cold pressure sealing type piezoelectric device element having an elliptical or elliptical metal outer ring. .

Furthermore, in the above embodiments, the hermetic terminals for piezoelectric devices such as quartz oscillators and surface acoustic wave devices have been described. However, hermetic terminals for electronic components and semiconductors for applications other than hermetic terminals for piezoelectric devices have been described. The same can be applied to a hermetic terminal for a device and other hermetic terminals.

Further, in the above-described embodiment, the case where the different (two kinds) metal layers which are alloyed by heating and become the brazing material are two layers is described, but the two kinds of metal layers are laminated in three or more layers. It may be formed. In such a case, a brazing material having a desired composition and made of a homogeneous alloy can be easily obtained.

Further, the thickness of the different kinds of metal layers which are alloyed by heating to become a brazing material is not limited to the range described in the embodiment, but the desired brazing material composition, application and necessary brazing strength. What is necessary is just to set suitably according to etc.

[0038]

The hermetic terminal of the present invention is a hermetic terminal in which a lead is hermetically sealed via a glass to a metal outer ring. Since the hermetic terminal is formed by laminating so that the noble metal layer is formed only in a small portion necessary for brazing, it does not contain harmful substance Pb, so-called Pb.
An airtight terminal that can easily provide a free relatively high melting point brazing material and can not only solve environmental problems, but also has a brazing material with a composition that is difficult to form from the beginning by alloy plating. Can be easily obtained. In addition, since a relatively expensive metal layer is provided only at a necessary portion at the tip of the lead, this kind of hermetic terminal can be provided at low cost.

Further, according to the method of manufacturing a hermetic terminal of the present invention, the tip of the lead is alloyed by heating to form a brazing material.
a step of forming a first metal layer made of any one of u, Ag, and Cu or an alloy thereof; a step of hermetically sealing the lead in a metal outer ring via glass; Forming a second metal layer made of Sn or an alloy thereof over the entire surface, so that the relatively expensive first metal layer is formed only on a necessary portion at the tip of the lead. By forming the second metal layer, the cost of the first metal layer can be reduced by reducing the amount of expensive metal used, and the relatively inexpensive second metal layer can be easily formed by a barrel plating method with a low formation cost. As a result, there is an effect that this kind of hermetic terminal can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hermetic terminal A for a press-fit type crystal unit according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the hermetic terminal A according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of an apparatus for partially plating Au on the tip of a lead, illustrating a method of manufacturing the hermetic terminal A according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a state before sealing of the hermetic terminal for explaining a method of manufacturing the hermetic terminal A according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a state after sealing of the hermetic terminal, illustrating a method of manufacturing the hermetic terminal A according to the first embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of the hermetic terminal A according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view of each stage when brazing a crystal vibrating piece to the tip of the lead of the hermetic terminal A according to the first embodiment of the present invention.

FIG. 8 is an Au—Sn binary alloy phase diagram for explaining the basis for determining the composition of the brazing material when brazing a quartz vibrating piece to the tip of the lead of the hermetic terminal A according to the first embodiment of the present invention.

FIG. 9 is a cross-sectional view of each stage when brazing a crystal vibrating piece to the tip of the lead of the hermetic terminal B according to the second embodiment of the present invention.

FIG. 10 is a cross-sectional view of each stage in brazing a crystal vibrating piece to the tip of a lead of an airtight terminal C according to a third embodiment of the present invention.

FIG. 11 is a cross-sectional view of each stage when brazing a crystal vibrating piece to the tip of a lead of an airtight terminal D according to a fourth embodiment of the present invention.

FIG. 12 is a plan view and a cross-sectional view taken along line XX of an airtight terminal E according to a fifth embodiment of the present invention.

FIG. 13 is a cross-sectional view of a conventional press-fit type crystal unit.

[Explanation of symbols]

 A, B, C, D, E Hermetic terminals 1, 17 Metal outer ring 2, 19 Glass 3, 20 Lead 4, 10, 14, 22 Au layer 5, 9, 12, 23 Sn layer 6 Quartz vibrating piece 7 Sn- Brazing material consisting of Au binary alloy 8 Cu layer 10 Brazing material consisting of Sn-Cu binary alloy 11 Ag layer 13 Brazing material consisting of Sn-Ag binary alloy 15 Sn-Cu alloy layer 16 Sn-Cu-Au ternary Brazing material made of alloy 18 Through hole 21 Ni layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01R 43/20 H01R 43/20 Z H03H 9/02 H03H 9/02 E

Claims (9)

[Claims] 1. A hermetic terminal in which a lead is hermetically sealed to a metal outer ring via glass via a glass, wherein a different kind of metal layer which is alloyed to the lead by heating to become a brazing material is replaced with a noble metal layer. An airtight terminal characterized by being laminated so that only a small part necessary for attachment is formed. 2. The method according to claim 1, wherein one of the dissimilar metal layers alloyed by heating to be a brazing material is one of Ag, Au, and Cu or an alloy thereof, and the other metal layer is Sn or an alloy thereof. The hermetic terminal according to claim 1, wherein the hermetic terminal is a layer. 3. One of the dissimilar metal layers which is alloyed by heating to become a brazing material is a lower one of Ag, Au, Cu or an alloy thereof, and the other metal layer is an upper layer. 3. The hermetic terminal according to claim 1, wherein the terminal is Sn or an alloy layer thereof. 4. A step of forming at least one of Au, Ag, and Cu as a brazing material or a first metal layer made of an alloy thereof at a tip portion of the lead by heating, and forming the lead into a metal. A method for manufacturing an airtight terminal, comprising: a step of airtightly sealing an outer ring via glass; and a step of forming a second metal layer made of Sn or an alloy thereof on the entire surface of the lead. 5. The method according to claim 4, wherein the first metal layer is formed by partial plating, and the second metal layer is formed by barrel plating. 6. The thickness of the first metal layer and the thickness of the second metal layer are set to be greater than the thickness of the second metal layer according to the composition of the brazing material formed by alloying. The method for manufacturing an airtight terminal according to claim 4, wherein the terminal is set to be small. 7. The hermetic terminal according to claim 4, wherein said first metal layer has a thickness of 1 to 7 μm, and said second metal layer has a thickness of 3 to 10 μm. Method. 8. A method in which a metal layer different from the first metal layer and the second metal layer formed on the lead is formed on the outer metal ring and hermetically sealed with the lead via glass. The method for manufacturing a hermetic terminal according to claim 4, wherein 9. The method for manufacturing a hermetic terminal according to claim 4, wherein said hermetic terminal is a hermetic terminal for a piezoelectric device for connecting and fixing a piezoelectric device element.