JP4544255B2 - Electronic component enclosure - Google Patents

Description

  The present invention relates to an electronic component encapsulant, and more particularly, to an electronic component encapsulant that provides a surge absorber that has excellent overvoltage characteristics and surge resistance and is excellent in mass productivity.

  Absorbs surge voltage applied to electronic devices for communication devices such as telephones, facsimiles, telephone exchanges, modems, etc., or a continuous overvoltage or overcurrent enters the electronic device and the electronic device or a print mounted thereon As a surge absorber for preventing the substrate from being thermally damaged or ignited, a surge absorbing element having a micro gap is hermetically sealed with an inert gas in a glass tube as shown in FIGS. Discharge-type surge absorbers have been provided (Japanese Patent Application No. 6-300514, Japanese Patent Application Laid-Open No. 7-320845).

The surge absorber shown in FIG. 3 has cap electrodes 4A and 4B covered on both ends of a microgap type surge absorber 3 in which a SnO ₂ conductive film 2 having a microgap 2A is formed on the surface of a cylindrical ceramic body 1. The worn one is inserted together with an inert gas (CO ₂ ) into a glass tube 5 made of lead glass, and both ends of the glass tube 5 are sealed with sealing electrodes 6A and 6B. Reference numerals 7A and 7B denote lead wires.

In the surge absorber shown in FIG. 3, in addition to absorbing an instantaneous surge voltage such as a lightning surge, the conductive coating 2 made of SnO ₂ is provided when there is a continuous overvoltage or overcurrent intrusion. It is presumed that the width of the micro gap 2A is widened due to thermal damage, which increases the discharge sustaining voltage, not only abnormal heat generation of the surge absorber, but also thermal damage and ignition of the electronic device and the printed circuit board on which this device is mounted. Etc. can be prevented.

  However, with this surge absorber, it is difficult to arrange the surge absorbing element 3 coaxially with the glass tube 5 when the surge absorbing element 3 is sealed in the glass tube 5. For this reason, the surge absorbing element 3 may not be positioned substantially at the center of the glass tube 5 but may approach one wall surface of the glass tube 5, and the glass tube 5 may be melted by heat during discharge.

  FIG. 4 has been proposed to solve this problem, and flanged cap electrodes 8A and 8B are used as cap electrodes to be attached to both ends of the surge absorbing element 3. FIG. That is, in the flanged cap electrodes 8A and 8B, since the flange protrudes toward the inner surface of the glass tube 5A, the surge absorbing element 3 is arranged near the axis in the glass tube 5A. Can be positioned. For this reason, the thermal melting of the glass tube due to the eccentricity of the surge absorbing element 3 is prevented.

In manufacturing the surge absorber shown in FIGS. 3 and 4, as a sealing electrode, a commercially available product having a lead wire attached to the end face in advance is used, and a cap electrode is placed in a glass tube in which the sealing electrode is inserted at one end. Is inserted, and then the sealing electrode is inserted into the other end of the glass tube and heated with a carbon heater to fuse the glass tube to the sealing electrode.
Japanese Patent Application No. 6-300514 Japanese Patent Laid-Open No. 7-320845

Flanged cap electrodes 8A shown in FIG. 4, the surge absorber using 8B, as described also in JP-A-7-320845, flanged cap electrodes 8A, the outer diameter _{R 1} of the flange portion of the 8B is is 2.4 mm, the inner diameter _{R 2} of the glass tube 5A for inserting this 2.7 mm, an outer diameter of the sealing electrodes 6A ', 6B' becomes 2.6 mm. Although there are some differences depending on the processing method, the length of the sealing electrode needs to be larger than the outer diameter, and in this case, at least about 3 mm is required.

Thus, in a surge absorber using a sealing electrode with a large outer diameter and length,
(1) It is disadvantageous for mass production in terms of processing and cost of the sealing electrode.
(2) The overall size of the surge absorber is also increased (for example, when a sealing electrode having a length of 3 mm is used, the length of the surge absorber is about 10 mm), which is disadvantageous for miniaturization.
(3) Since the outer diameter of the sealing electrode is too large with respect to a common lead wire diameter of 0.5 mm, handling is poor, and it is not easy to transfer to a jig during heat sealing with a carbon heater. This is also disadvantageous for mass production.
There is a problem.

  The surge absorber shown in FIG. 3 does not have such a problem, but as described above, there is a problem of glass tube melting due to the eccentricity of the surge absorbing element.

  The present invention solves the above-described conventional problems, and in a surge absorber using a flanged cap electrode for positioning of a surge absorbing element, an electronic component encapsulant capable of using a small sealing electrode suitable for mass production The purpose is to provide.

The electronic component enclosure of the present invention is an electronic component enclosure in which an electronic component is inserted into a glass tube, sealing electrodes are inserted at both ends of the glass tube, and both ends of the glass tube are sealed. A glass tube is inserted into both ends of the tube, the sealing electrode is inserted into the glass tube, and the glass tube is an electronic component enclosure that is fused to the glass tube and the sealing electrode , A flanged cap electrode for placing the electronic component in the vicinity of the axial center in the glass tube is attached to both ends of the electronic component, and the flanged cap electrode is attached to both ends of the electronic component. It has a bottomed cylindrical cap portion and a flange portion projecting outward from the opening end of the cap portion, and at one end side of the glass tube, the glass tube extends in the axial center extending direction. The length is longer than the length in the axial direction of the sealing electrode The sealing electrode is inserted into one end side of the glass tube, and the cap portion of the cap electrode with flange is inserted into the other end side of the glass tube to contact the sealing electrode. The other end surface of the glass tube is in contact with the flange portion of the flanged cap electrode .

  With such an electronic component enclosure, the radius of the sealing electrode to be used can be reduced by an amount corresponding to the thickness of the glass tube, and therefore a small-sized sealing electrode can be used. As a result, it is possible to manufacture a relatively small electronic component enclosure with high productivity.

  The electronic component encapsulant of the present invention is suitable for an electronic component in which a surge absorbing element is encapsulated. In particular, the electronic component is disposed near the axial center in a glass tube, such as a cap electrode with a flange at both ends thereof. This is effective for the case where the positioning member is mounted.

  The glass softening point of the glass tube is preferably lower than the glass softening point of the glass tube.

  According to the electronic component encapsulant of the present invention, a relatively small electronic component encapsulant can be manufactured with high productivity using a small sealing electrode suitable for mass production.

  The electronic component enclosure of the present invention is sealed in a glass tube by attaching cap electrodes with flanges at both ends of the surge absorber in order to prevent melting of the glass tube due to eccentricity of the surge absorber in the glass tube. Therefore, it is possible to realize a small surge absorber that is suitable for a surge absorber and that can be easily mass-produced, and that has excellent overvoltage characteristics and surge resistance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a surge absorber to which an electronic component enclosure according to the present invention is applied, and FIGS. 2A to 2C are cross-sectional views showing a procedure for manufacturing the surge absorber. 1 and 2, members having the same functions as those shown in FIGS. 3 and 4 are denoted by the same reference numerals.

  In this surge absorber, the surge absorbing element 3 having cap electrodes 8A and 8B with flanges attached to both ends is inserted into the glass tube 5B, and the sealing electrodes 6A and 6B are inserted into both ends of the glass tube 5B. Thus, both ends of the glass tube 5B are sealed. Glass tubes 9A and 9B are inserted into both ends of the glass tube 5B. Sealing electrodes 6A and 6B are inserted into the glass tubes 9A and 9B, and the glass tubes 9A and 9B are sealed with the glass tube 5B. Sealing is performed by being fused to the electrodes 6A and 6B.

  The glass softening points of the glass tubes 9A and 9B are lower than the glass softening point of the glass tube 5B.

In such a surge absorber, the inner diameter of the glass tube 5B is increased to some extent in order to insert the surge absorbing element 3 with the flanged cap electrodes 8A and 8B attached thereto, but the outer diameter of the sealing electrodes 6A and 6B. Is sufficient if it matches the inner diameter of the glass tubes 9A, 9B. Thus, the sealing electrodes 6A, as 6B, a sealing electrode 6A of the conventional surge absorber shown in FIG. 4 ', 6B' smaller diameter than, for example, sealing electrodes 6A of the surge absorber shown in FIG. 3, as with 6B A general-purpose sealing electrode can be used.

  Next, a procedure for manufacturing such a surge absorber will be described with reference to FIGS. Note that the carbon heater is not shown in FIGS.

  This surge absorber can be manufactured in the same manner as a conventional surge absorber except that a glass tube is used.

That is, first, sequentially inserted glass tube 5B, the glass tube 9 B and the lead wire 7B with the sealing electrode 6B the inclusion of the lower heater carbon heater. Then, the surge absorbing element 3 with the flanged cap electrodes 8A and 8B attached to both ends is inserted into the glass tube 5B (FIG. 2A).

Therefore, the glass tube 9 B is, with a larger sealing area the contact surface between the sealing electrode 6B which are inserted into one end of the glass tube 5B is sufficiently secured, and the cap electrode 8B of the surge absorber 3 to so as not to interfere with the contact between the sealing electrode 6B, the glass tube 9B length L _B is the length L ₁ or more sealing electrodes 6B, and the lower side in FIG. 2 should lower end is the length L ₂ or less to the flange portion of the cap electrode 8B from the sealing electrode 6B.

  Next, after the glass tube 9A is inserted so as to contact the flange portion of the cap electrode 8A of the surge absorbing element 3 in the glass tube 5B, the upper heater of the carbon heater into which the sealing electrode 6A with the lead wire 7A is transferred is covered. (FIG. 2 (b)), put in a sealing device, and heat and seal at 550 to 750 ° C. for about 1 to 3 minutes (FIG. 2 (c)).

Therefore, for the glass tube 9A, the glass tube 9A is secured so that the contact surface with the sealing electrode 6A is sufficiently secured to increase the sealing area, and the glass tube 9A can be held by the flange portion of the cap electrode 8A. The length L _A of the tube 9A needs to be not less than the length L ₃ from the flange portion of the cap electrode 8A of the surge absorbing element 3 inserted into the glass tube 5B to the upper end of the upper sealing electrode 6A in FIG. There is.

Normally, as shown, the length L _B of the glass tube 9B is a length about the same sealing electrodes 6B, also the length L _A of the glass tube. 9A, the sealing flange portion of the cap electrode 8A It is the length L ₃ to the upper end of the electrode 6A and the same degree.

  The ceramic body 1 constituting the surge absorbing element 3 is made of insulating ceramics such as mullite, alumina, beryllia, stearite, forsterite, zircon, ordinary porcelain, glass ceramic, silicon nitride, aluminum nitride, and silicon carbide. Is used.

Further, as the conductive film 2, a SnO ₂ film having a thickness of about 0.3 to 0.5 μm is generally used, and such a conductive film 2 is formed by a sputtering method, a vapor deposition method, an ion plating method, a plating method. The film is formed by various thin film forming methods such as a CVD method. The microgap 2A is formed in a width of 10 to 200 μm in a normal case by laser processing the conductive film 2 formed in this way. In the case of a surge absorber that does not require overvoltage characteristics, the conductive coating 2 is not limited to SnO ₂ but can be made of a wide conductive material such as Ti, TiN, or W.

  Moreover, as glass tube 5B and glass cylinder 9A, 9B, the thing made from lead glass is suitable.

  The glass tubes 9A and 9B preferably have the same composition, and the glass tube 5B preferably has a glass composition with a higher softening point.

Glass tube 9A, _{T 9} the softening point of the glass 9B, if the softening point of the glass of the glass tube 5B was _{T 5,} preferably the temperature T at the time of the above sealing and _T 9 <T _{<T 5} .

  The inner diameter of the glass tube 5B is preferably 2 to 3 times the outer diameter of the ceramic body 1.

  The thickness and inner diameter of the glass cylinders 9A and 9B are appropriately determined so that general-purpose sealing electrodes 6A and 6B can be used with respect to the inner diameter of the glass tube 5B.

  As the cap electrodes 8A and 8B, those in which a flange portion is formed by pressing a stainless steel plate having a thickness of about 0.1 to 0.2 mm are used.

  It is preferable to use a commercially available jumet wire as the surge absorber.

Further, CO ₂ is suitable as the enclosed gas in the glass tube 5B.

  The above description is about the case where the present invention is applied to a surge absorber. However, the electronic component encapsulant of the present invention is not limited to a surge absorber, but a flanged cap electrode such as a resistor or a semiconductor. The present invention can be suitably applied to a device that uses a positioning member for placing an electronic component to be sealed in the vicinity of an axis in a glass tube.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1
The surge absorber shown in FIG. 1 was produced by the procedure shown in FIGS. 2A to 2C with the enclosed gas CO ₂ , the sealing temperature 740 ° C., and the sealing time 1 minute. The dimensions and materials of the parts used are as follows.

Surge absorbing element 3: A ceramic body 1 made of a mullite sintered body formed with a SiO ₂ conductive film (thickness 1 μm) 2 having a micro gap 2A of 30 μm width, diameter 1.00 mm, length 3mm
Cap electrodes with flanges 8A and 8B: Made of stainless steel, flange outer diameter 2.4mm, wall thickness 0.15mm
Glass tube 5B: lead glass softening point 695 ° C.,
Outer diameter 5.1mm, Inner diameter 2.7mm, Length 7.5mm
Glass cylinder 9A: lead glass softening point 550 ° C.,
Outer diameter 2.6mm, inner diameter 1.6mm, length 2.5mm
Glass tube 9B: lead glass softening point 550 ° C.,
Outer diameter 2.6mm, inner diameter 1.6mm, length 1.8mm
Sealing electrodes 6A and 6B: Made of mass-produced jumet (Ni-Fe alloy with a cuprous oxide layer formed on the surface), diameter 1.5mm, length 1.8mm
Lead wires 7A and 7B: cp copper-coated steel lead wires having a wire diameter of 0.5 mm

  In this embodiment, a general-purpose general device could be used as the carbon heater jig and sealing device.

The following 10 performance evaluations of the obtained surge absorber were performed, and the results are shown in Table 1.
I Overvoltage test An overvoltage of 600 V AC at 0.25 A was applied to the surge absorber for 30 minutes, and the discharge stop state in the micro gap was examined.
II Surge Withstand Test The 8/20 μs surge was applied to the surge absorber three times, and the maximum applied current value at which all 10 samples were not destroyed was examined.
III Mass productivity The quality of mass production was evaluated in comparison with Comparative Example 2 described later from the availability of the parts used, the price, the versatility of the sealing device and the heater jig, the number of manufacturing steps, and the like.
IV Size As the dimensions of the surge absorber, the length of the glass tube used was observed.

Comparative Example 1 (Surge Absorber of JP-A-7-320845)
In Example 1, the surge absorber shown in FIG. 4 was produced in the same manner except that the following were used as the sealing electrode and the glass tube without using the glass tube, and the evaluation was performed in the same manner. It was shown to.

Sealing electrodes 6A 'and 6B': Made of Jumet (not mass-produced), diameter 2.6mm, length 3mm
Glass tube 5A: made of lead glass, outer diameter 5.1 mm, inner diameter 2.7 mm, length 9.6 mm

Comparative Example 2 (Surge Absorber of Japanese Patent Application No. 6-300514)
In Example 1, a surge absorber shown in FIG. 3 was prepared in the same manner except that the following cap electrode without flange was used instead of the cap electrode with flange, and the following was used as the glass tube. The results are shown in Table 1.

Cap electrodes 4A, 4B: Made of stainless steel, wall thickness 0.15mm
Glass tube 5: made of lead glass, outer diameter 3.1 mm, inner diameter 1.8 mm, length 7.5 mm

  From Table 1, it can be seen that according to the present invention, a small surge absorber having good overvoltage characteristics and a large surge resistance can be manufactured with high mass productivity.

It is sectional drawing of the surge absorber which shows one Example of the electronic component enclosure of this invention. It is sectional drawing which shows the manufacture procedure of the surge absorber shown in FIG. It is sectional drawing which shows a prior art example. It is sectional drawing which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic body 2 Conductive film 2A Micro gap 3 Surge absorption element 5, 5A, 5B Glass tube 6A, 6B, 6A ', 6B' Sealing electrode 7A, 7B Lead wire 8A, 8B Cap electrode with flange 9A, 9B Glass Tube

Claims (3)

In an electronic component enclosure in which an electronic component is inserted into a glass tube, sealing electrodes are inserted at both ends of the glass tube, and both ends of the glass tube are sealed,
An electronic component enclosure in which glass tubes are inserted into both ends of the glass tube, the sealing electrode is inserted into the glass tube, and the glass tube is fused to the glass tube and the sealing electrode, respectively. And
At both ends of the electronic component, a cap electrode with a flange for mounting the electronic component near the axis in the glass tube is mounted,
The cap electrode with flange has a bottomed cylindrical cap portion that is attached to both ends of the electronic component, and a flange portion that projects outward from the opening end of the cap portion,
On the one end side of the glass tube, the length of the glass tube in the axial center extending direction is longer than the length of the sealing electrode in the shaft center extending direction, and one end side in the glass tube The sealing electrode is inserted into the glass tube, the cap portion of the cap electrode with flange is inserted into the other end side of the glass tube and is in contact with the sealing electrode, and the other end surface of the glass tube is in contact with the sealing electrode. An electronic component enclosing body which is in contact with a flange portion of a cap electrode with a flange .   2. The electronic component enclosure according to claim 1, wherein the electronic component is a surge absorbing element. 3. The electronic component enclosure according to claim 1, wherein the softening point of the glass tube is lower than the softening point of the glass tube.

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