JP2001068194A - Electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component having a Pb-free low melting point brazing metal layer used in place of Sn-Pb eutectic solder. SOLUTION: This electronic component has Pb-free high melting point brazing metal layers 4, 4 in the exposed part of a metal outer ring 1 of a gastight terminal A and on the inner side of leads 3, 3, and low melting point brazing metal layers 5, 5 selected from the group of an Sn-Ag base alloy and an Sn-Bi base alloy formed by plating on at least the surface on the outer side of the leads 3, 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electronic component,
More specifically, Pb which is an alternative to Sn-Pb eutectic solder
The present invention relates to an electronic component such as an airtight terminal plated with a free brazing material layer.

[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 the 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 to 99 w
A Pb-Sn alloy having a composition of t% -Sn1 to 10 wt% is used. This high temperature solder has a liquidus temperature of 320
C. and the solidus temperature is 310 C.

[0003]

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, alternative solders called Pb-free have been developed and studied. Such Pb-free alternative solders have been developed and studied exclusively as alternatives to Sn-Pb eutectic solders, and have a melting point as close as possible to the melting temperature of the eutectic point of Sn-Pb eutectic solder, which is 183 ° C. Is required.

The required quality characteristics (basic quality) common to the Pb-free substitute brazing material for the Sn—Pb eutectic solder and the Pb-free substitute material for the Pb—Sn high melting point solder are as follows.
There are the following: Capable of press-fit sealing. (Press-Fit Sealing) This is because the most general press-fitting and sealing can be performed as a sealing method for the cylindrical quartz resonator. No gas generation. (Non-gas generation) This is to prevent the fluctuation of the characteristics of the electronic components housed inside the quartz oscillator and various electronic components due to the gas generated from the brazing material during and after sealing. is there. Good adhesion. (Adhesiveness) This is a Pb-free alternative low melting point brazing material and P
This is because the b-free alternative high melting point brazing material firmly adheres to various brazing members. Bonding with the substrate is possible. (Substrate bondability) This is to ensure the bondability of an electronic component such as a quartz oscillator to a printed board, which is a general brazing member.

[0005] The following manufacturing requirements are common to the Pb-free alternative low melting point brazing material and the Pb-free alternative high melting point brazing material. Formable by wet plating. (Wet plating property) This is when the brazing material layer can be formed only by a so-called dry plating method such as vapor deposition, spatter, CVD, etc., even if the brazing material has excellent physical properties (basic quality). This is because the production cost is high and is not practical, so that the formation is easy and the formation by the inexpensive wet plating method is ensured.

[0006] The following properties are required as an alternative low melting point brazing material for the above-mentioned Sn-Pb eutectic solder. The heat resistance temperature is 160 ° C or higher. (Heat resistance) If the heat resistance temperature is lower than this, the substitute solder melts or softens in the use environment of the electronic component such as the crystal resonator, and the electronic component element such as the crystal resonator element drops or moves. This is because various inconveniences are not caused. Easy element bonding by melting. (Element bondability) This is to ensure the bondability of the electronic element such as the quartz vibrating piece by melting. There must be bonding reliability with the substrate. (Substrate bondability) This is to ensure the bondability of an electronic component such as a quartz oscillator to a printed circuit board.

[0007] Pb-free Pb- resistant to reflow temperature
As a high melting point brazing material in place of Sn, the following properties must be satisfied. The heat resistance temperature is 260 ° C or higher. (High melting point) This is an expected basic required characteristic as a Pb-free high melting point brazing material that can withstand the reflow temperature. Brazing is possible by melting. (Brazing property) This is a basic required characteristic as a brazing material. 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. (Silver plating property) This is to secure the deposition property and fixation property of silver plating when finish silver plating is performed in terms of surface gloss and aesthetics while the surface of the brazing material is exposed. Required characteristics.

Accordingly, an object of the present invention is to provide an electronic component having a Pb-free Sn-Pb alternative low melting point brazing material layer that satisfies the above various required characteristics.

[0009]

According to the present invention, there is provided an electronic component comprising:
An electronic component having a brazing material layer containing one material selected from the group consisting of an n-Ag-based alloy and a Sn-Bi-based alloy alone or as a main material.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
An electronic component having a brazing material layer containing one material selected from the group consisting of a Sn-Ag-based alloy and a Sn-Bi-based alloy alone or as a main material. Here, the reason why the brazing material layer is limited to the Sn-Ag alloy and the Sn-Bi alloy is that the Sn-Ag alloy and the Sn-Bi alloy are made of Pb.
This is because various required characteristics as a free alternative low melting point brazing material layer are satisfied.

The invention according to claim 2 of the present invention is characterized in that the brazing material layer is a low melting point brazing material layer made of a Sn-Ag alloy containing 1 to 15 wt% Ag.
An electronic component as described. Here, Ag is 1 to 15 wt%.
If it is less than 1 wt%, whiskers may be generated, and if it exceeds 15 wt%, the liquidus temperature becomes high, and it becomes difficult to mount electronic components such as crystal vibrating pieces on a printed circuit board or the like. .

[0012] The invention according to claim 3 of the present invention is characterized in that the brazing material layer is a low melting point brazing material layer made of a Sn-Bi-based alloy containing 1 to 20 wt% Bi.
An electronic component as described. Here, Bi is 1 to 20 wt%.
If it is less than 1 wt%, whiskers may occur, and if it exceeds 20 wt%, the melting point becomes too low.

According to a fourth aspect of the present invention, there is provided the electronic component according to any one of the first to third aspects, wherein the brazing material layer has an antioxidant film on a surface thereof. Here, the reason why the antioxidant film is formed on the surface of the brazing material layer is that even if the constituent material of the brazing material layer is easily oxidized, the surface oxidation of the brazing material can be prevented.

The invention according to claim 5 of the present invention is characterized in that the electronic component is an airtight terminal having a lead hermetically sealed to a metal outer ring via glass.
An electronic component as described. Here, the reason why the electronic component is limited to the hermetic terminal is that the hermetic terminal is generally used as a component of the electronic component to be brazed, and its use is guaranteed.

According to a sixth aspect of the present invention, the airtight terminal is provided on at least a surface on an outer side of the lead.
6. The electronic component according to claim 1, wherein the terminal is a hermetic terminal having a b-free brazing material layer formed thereon. Here, the reason why the electronic component is limited to the hermetic terminal is that the hermetic terminal is generally used as a component of the electronic component to be brazed to a mounting board such as a printed board, and its use is guaranteed.

According to a seventh aspect of the present invention, there is provided an electronic component according to the sixth aspect, wherein the hermetic terminal is a hermetic terminal for a press-fit type crystal unit having a cylindrical metal outer ring. is there. Here, the reason why the hermetic terminal is limited to the hermetic terminal for a press-fit type crystal unit is that this kind of hermetic terminal is press-fitted into a metal cap, connection and attachment of a crystal vibrating piece to the inner end of the lead,
Despite the strict requirements for brazing materials, such as bending of leads and connection of the outer ends of leads to printed circuit boards, etc., the Pb-free alternative low melting point brazing material of the present invention can satisfy these characteristics. It is.

In the invention according to claim 8 of the present invention, the airtight terminal has a high melting point brazing material layer formed at least on the exposed portion of the metal outer ring and at least on the inner side of the lead, and at least on the outer side of the lead. An electronic component having a low melting point brazing material layer formed on a surface. As described above, the high melting point brazing material layer is formed on the exposed portion of the metal outer ring and the inside of the lead, and the low melting point brazing layer is formed on the outside of the lead. After brazing an electronic element such as a crystal vibrating piece with a high melting point brazing material layer, and then brazing the outer side of the lead to a printed circuit board, etc.
At the reflow temperature when brazing the outer side of the lead to the printed circuit board etc., the electronic element such as the crystal vibrating piece brazed to the inner side of the lead does not fall off or move due to melting or softening of the brazing material. .

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a cylindrical press-fitting type crystal unit airtight terminal A which is an electronic component of one embodiment 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.
-Ni alloy, Fe-Ni-Co alloy or the like, having 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, 3 are made of an Fe-Ni alloy, an Fe-Ni-Co alloy, or the like, and have an outer diameter of 0.15.
0.3 mm.

FIG. 2 shows that the next high melting point brazing material layers 4 and 4 are formed on the exposed portion of the metal outer ring 1 of the hermetic terminal A and on the inner side of the leads 3 and 3. It is a perspective view of the state where the next low melting point brazing material layers 5 and 5 were formed on the outer side. The brazing material layers 4 and 4 are formed to a thickness of, for example, about 5 to 30 μm by, for example, wet barrel plating.

The high melting point brazing material layers 4 and 4 are, for example, as follows. Sn-Zn: Sn 10-70 wt% -Zn 30-9
0 wt% liquidus temperature / solidus temperature = 400/232 ° C. Sn-Au: Sn 65-80 wt% -Au 20-35
wt% liquidus temperature / solidus temperature = 480/280 ° C Zn: Zn 100wt% liquidus temperature / solidus temperature = 419/419 ° C Bi: Bi100wt% liquidus temperature / solidus temperature = 271 / 271 ° C

The low melting point brazing material layers 5, 5 are any one selected from the following group. Sn-Ag: Sn 95-99 wt% -Ag 1-15
wt% liquidus temperature / solidus temperature = 280/221 ° C. Sn-Bi: Sn 80-99 wt% -Bi 1-20
wt% liquidus temperature / solidus temperature = 230/139 ° C

The following Table shows the evaluation results of the above-mentioned various brazing materials with respect to the above-mentioned various required characteristics.

[Table 1]

FIG. 3 is a perspective view in which a rectangular crystal vibrating piece 6 as an example of an electronic element is fixed to the inner ends of the leads 3 and 3 of the hermetic terminal A. The crystal vibrating piece 6 is
No. 0, electrodes 61 and 62 are formed on both surfaces. Then, the electrodes 61 and 62 are brought into contact with the brazing material layers 4 and 4 attached to the leads 3 and 3, and are attached to the leads 3 and 3 by, for example, a method of irradiating a laser or hot air. By melting the brazing material layers 4, 4, they are electrically connected and mechanically fixed to the leads 3, 3. The reason why the quartz vibrating reed 6 is brazed and fixed to the leads 3 and 3 by a local heating method of irradiating a laser or hot air is to prevent the characteristic change of the quartz vibrating reed 6 due to heating during brazing. That's why.

FIG. 4 shows a quartz vibrating reed 6
FIG. 6 is a cross-sectional view of the crystal unit 8 in a state where the hermetic terminal A to which is fixed is press-fitted into a bottomed cylindrical metal cap 7 and fixedly sealed.

The metal cap 7 is made of, for example, Cu (45-65 wt%)-Ni (6-35 wt%) which is called nickel silver.
-Zn (15-35 wt%) alloy, and the inner diameter of the metal outer ring 1 of the hermetic terminal A is, for example, 1.
In the case of 6 mm, a slightly smaller diameter, for example, 1.55 m
m. Then, the hermetic terminal A is press-fitted into the open end of the metal cap 7 to be sealed.
Therefore, in order to facilitate the initial insertion of the metal outer ring 1 into the opening of the metal cap 7, the shoulder at the upper end of the metal outer ring 1 is formed as a rounded gentle curved surface as shown in the figure. It is desirable to keep. Such a shape can be easily obtained, for example, by manufacturing the metal outer ring 1 from a plate-like material by drawing press forming and press punching.

Such press-fit sealing is performed based on the dimensional relationship between the metal outer ring 1 and the metal cap 7.
Of the metal outer ring 1 and the brazing material layer 4 applied to the outer periphery of the metal outer ring 1 fills the gap therebetween. Therefore, sufficient airtightness can be obtained. If necessary, use a metal cap 7
A brazing material layer may be formed on the inner surface of the substrate. At the time of press-fitting, the glass 2 receives a strong compressive stress, but the glass is strong against the compressive stress, from the relationship between the outer diameter Φ1 of the metal outer ring 1 and the inner diameter Φ2 of the metal cap 7 (Φ1> Φ2). Therefore, it is not destroyed by the compressive stress. Such press-fit sealing does not require heating at the time of sealing as compared with sealing with a molten brazing material or sealing with low-melting glass, so it is not only advantageous in terms of equipment, but also has a crystal vibration caused by heating. The piece 6 does not deteriorate to cause a characteristic change. Moreover, no gas is generated as compared with resin sealing, so that the generated gas during sealing and / or after sealing does not cause deterioration of the quartz vibrating piece 6 and change in characteristics.

FIG. 5 is a partial cross-sectional front view showing a state where the above-described crystal resonator 8 is brazed to a conductive layer 10 of a mounting board 9 such as a printed board by a brazing material 11. That is, the leads 3 and 3 of the crystal unit 8 are inserted into the through holes 9 a and 9 a of the mounting board 9, and the Sn−
The lead 3 is brazed to the conductive layer 10 of the mounting board 9 by reflowing a molten brazing material 11 obtained by melting a Pb-free brazing material instead of Pb eutectic solder. The brazing material 11 used for the reflow is a solder having a relatively low melting point, for example, a liquidus temperature of less than 250 ° C., which is a substitute for the Sn—Pb eutectic solder, for example, a Sn—Ag alloy or a Sn—Bi alloy. Materials are used. The melting point of the reflow brazing material 11 is, for example, relative to the liquidus temperature of the high melting point brazing layers 4 and 4 that are adhered to the leads 3 and 3 of the hermetic terminal A and fix the crystal vibrating piece 6. And 30 ° C. or higher, more preferably 50 ° C.
Use the one with the above difference. In such a case, the brazing material layer 4 to which the crystal vibrating piece 6 is fixed melts at the heating temperature at the time of the reflow fixing work of the crystal resonator 8 to the conductive layer 10 of the mounting substrate 9 and the crystal vibrating piece 6 becomes The vibration characteristics are not deteriorated by dropping from the leads 3 and 3 or by the softening of the brazing material layer 4 and the movement of the crystal vibrating piece 6 to contact the metal cap 7. When the leads 3, 3 of the crystal unit 8 are fixed to the conductive layer 10 of the mounting substrate 9 by the reflow soldering material 11, the low melting point brazing material layers 5, 5 formed on the leads 3, 3 are reflowed. This helps to ensure the wettability of the brazing material 11 to the leads 3 and 3 and to assure reliable substrate bonding and bonding reliability.

FIG. 6 is an enlarged sectional view of a main part showing a state of the brazing member before brazing when the brazing material is easily oxidized. That is, for example, Zn has an advantage that it can be easily formed by plating, but is easily oxidized and is difficult to be left in air or brazed. Therefore, the brazing members 12, 1
3, high melting point brazing material layers 14 and 15 made of Zn and having a thickness of about 5 to 30 μm are formed, and the brazing material layers 14 and 15 are formed.
The surface of which is covered with Sn films 16 and 17 having a thickness of about 100 to 1000 Å formed by flash Sn plating as an example of an antioxidant film to prevent oxidation during standing in air or brazing. It is. The Sn films 16 and 17 for preventing oxidation have a relatively low melting point at 198 ° C. due to heating during brazing.
Eutectic with Zn that constitutes 4, 15
Only the surfaces of the brazing material layers 14 and 15 are melted.
After the dough is temporarily fixed, the melting temperature of Zn 4
Since it is taken into the high melting point brazing material layers 14 and 15 melted by heating to a temperature higher than 19 ° C., for example, 419 ° C., there is no problem.

When brazing the electronic component of the present invention,
By heating a binary alloy alone or a brazing material layer mainly composed of any one of the above-described Sn—Ag-based alloy and Sn—Bi-based alloy at a temperature equal to or higher than the liquidus temperature,
Not only the method of completely melting and brazing, but also heating at the temperature where the solid phase still remains, that is, the temperature between the solidus temperature and the liquidus temperature, so that the solid phase and the liquid phase coexist Alternatively, a brazing method may be adopted in which the final brazing is completed only with the molten liquid phase by solidifying in a state in which the brazing is performed. When such a brazing method is employed, the brazing temperature can be set lower than in a brazing method in which the brazing material is completely melted by heating at a temperature equal to or higher than the liquidus temperature, so that the brazing apparatus is inexpensive. Not only is the maintenance cost reduced, but also the advantage that the brazing temperature can be set to an arbitrary temperature between the solidus temperature and the liquidus temperature in accordance with the heat-resistant temperature of the brazing member, etc. is there.

The above embodiment of the present invention has been described with respect to a specific electronic component. However, the present invention is not limited to the above embodiment, and may be implemented within the spirit and scope of the present invention.
It goes without saying that various modifications are possible.

For example, in the above embodiment, the low melting point brazing material layer 5 is formed on the entire outer sides of the leads 3 and 3 of the hermetic terminal A.
5 has been described, the printed circuit board 9 is formed.
It may be formed only in the vicinity of the outer end necessary for connection with.

In the above embodiment, the airtight terminal A
The case where only the low melting point brazing layers 5 and 5 are formed on the outer side of the leads 3 and 3 has been described, but the high melting point brazing layer and the exposed portion of the metal outer ring 1 and the inner side of the leads 3 and 3 are formed. 4,4
Is formed at the same time on the outer sides of the leads 3 and 3, and then the low melting point brazing layers 5 and 5 are formed only on the outer sides of the leads 3 and 3. May be formed. In such a case, an easy and inexpensive wet barrel plating method can be adopted as a method of forming the high melting point brazing material layers 4, 4, so that there is an advantage that the processing cost of forming the high melting point brazing material layers 4, 4 can be reduced. Not only that, when the leads 3 and 3 are fixed to the mounting board 9 such as a printed board, there is an advantage that the wettability of the reflow brazing material 11 to the leads 3 and 3 can be ensured and the brazing can be reliably performed. .

Further, in the above embodiment, the airtight terminal for the press-fit type quartz crystal unit having a right outer cylindrical metal outer ring has been described as an electronic component.
The shape of the metal outer ring 1 may be formed as an inclined surface having a smaller diameter as going from the middle part of the height dimension to the upper part toward the upper part, and may be formed in a cylindrical shape from the middle part to the lower part. Such a shape also facilitates the initial insertion and press-fitting of the metal outer ring into the metal cap.

Further, in the above embodiment, the brazing of the lead and the quartz vibrating piece in the hermetic terminal for the quartz vibrator in which the outer metal ring has a straight cylindrical shape has been described as the brazing member. The same can be applied to a hermetic terminal for a crystal resonator having a shape or an elliptical shape.

Further, in the above embodiment, the hermetic terminal for the press-fit sealed type crystal unit has been described. It can be implemented similarly.

Further, in the above embodiment, the airtight terminal for the crystal oscillator has been described. However, the airtight terminal for electronic parts and semiconductor devices other than the airtight terminal for the crystal oscillator is also used. It can be implemented similarly.

Further, the thickness of the brazing material layer is not limited to the range described in the embodiment, but may be appropriately set according to the application.

[0038]

According to the present invention, there is provided an electronic component in which a brazing material layer formed solely of any one material selected from the group consisting of a Sn-Ag alloy and a Sn-Bi alloy or a main material thereof is formed. Therefore, it is possible to provide a conventional electronic component having a so-called Pb-free brazing material layer having a relatively low melting point that does not contain Pb, which is a harmful substance, and has the effect of clearing environmental problems.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hermetic terminal A for a press-fit type crystal unit before a brazing material layer is formed as an electronic component according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an airtight terminal A for a press-fit type crystal unit after a brazing material layer is formed as an electronic component according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a state in which a crystal vibrating piece as an example of an electronic element is connected and fixed to the inner side of a lead of a hermetic terminal A for a press-fit type crystal resonator as an electronic component according to a first embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing the crystal resonator in a state where the hermetic terminal A for the crystal resonator according to the first embodiment of the present invention is press-fitted and sealed in an opening of a metal cap.

FIG. 5 is a side view showing a cross section of a part of a state where the crystal unit of the present invention is brazed to a mounting substrate such as a printed circuit board.

FIG. 6 is an enlarged longitudinal sectional view of a main part for describing a method of brazing an electronic component according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List A Airtight terminal 1 Metal outer ring 2 Glass 3 Lead 4 Pb-free high melting point brazing material layer 5 Pb-free low melting point brazing material layer 6 Quartz crystal vibrating piece 7 Metal cap 8 Quartz crystal vibrator 9 Mounting substrate (printed circuit board) 10 Conductive layer 11 Low melting point reflow brazing material 12, 13 Electronic component 14, 15 Brazing material layer (Zn layer) 16, 17 Antioxidant film (Sn film)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 9/05 H01R 9/09 D

Claims (8)

[Claims] An electronic component constituting member has at least a part thereof
An electronic component comprising a brazing material layer formed solely or solely of any one material selected from the group consisting of an n-Ag-based alloy and a Sn-Bi-based alloy. 2. The electronic component according to claim 1, wherein the brazing material layer is a low melting point brazing material layer made of a Sn—Ag alloy containing 1 to 15 wt% of Ag. 3. The electronic component according to claim 1, wherein the brazing material layer is a low melting point brazing material layer made of a Sn—Bi-based alloy having a Bi content of 1 to 20 wt%. 4. The electronic component according to claim 1, wherein said brazing material layer has an antioxidant film on a surface thereof. 5. The electronic component according to claim 1, wherein the electronic component is a hermetic terminal in which leads are hermetically sealed to a metal outer ring via glass. 6. The electronic component according to claim 1, wherein the brazing material layer is formed on an outer side of a lead of the hermetic terminal. 7. The electronic component according to claim 6, wherein said hermetic terminal is a hermetic terminal for a press-fit type quartz resonator having a metal outer ring having a cylindrical shape. 8. The airtight terminal, wherein a high melting point brazing material layer is formed at least on the exposed portion of the metal outer ring and at least on the inner side of the lead, and a low melting point brazing material layer is formed on at least the outer surface of the lead. The electronic component according to claim 6, wherein the electronic component is formed.