JPS6239541B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a press-fitting method, and particularly to a press-fitting method that is advantageously used, for example, when press-fitting a hermetic terminal into a metal cap.

Electronic components such as semiconductor elements and crystal oscillators are subject to large changes in characteristics due to humidity and the like, so their characteristics are generally stabilized by being sealed in an airtight container. This airtight container generally includes a stem, which is an airtight terminal, and a metal cap, which is an airtight terminal formed by sealing a lead wire to a metal outer ring through glass in an airtight and insulating manner. Resistance welding, soldering, cold pressure welding, press-fitting, etc. are used to seal the stem and cap, but resistance welding and soldering involve a rise in temperature and, moreover, welding During cold welding, molten metal may cause scattering or gas generation, which can easily cause deterioration of the characteristics of electronic components.Although cold pressure welding does not have the above-mentioned problems because it is a cold process, It must be made of a cladding material of a soft metal such as copper that can be welded by pressure, and a sealing metal material such as Kovar (Fe-Ni-Co alloy) that can be sealed with glass, reducing material costs. Not only does this increase the height of the glass, but also a large pressure stress is instantaneously applied, which causes large deformation of the stem, cap, etc., which causes the problem that cracks are likely to occur in the glass.

Therefore, the press-fitting method is widely used for crystal resonators.

FIG. 1 shows a cross-sectional view of an example of such a crystal oscillator. In the figure, reference numeral 1 denotes a stem made of an airtight terminal, which is connected to a metal outer ring 2 made of Kovar (Fe-Ni-Co alloy) or the like through a sealing glass 3 made of borosilicate glass or the like.
The lead wire 4 of the book is hermetically sealed. Reference numeral 5 denotes a tuning fork-shaped crystal resonator, which is sandwiched and fixed between the inner ends of the two lead wires 4. 6 is nickel silver (Cu-
The cap is made of Zn-Ni alloy), etc. Note that a highly malleable metal layer such as Pb-Sn alloy or In is formed on either or both of the outer peripheral surface of the metal outer ring 2 and the inner surface of the opening of the cap 6 for airtight sealing. However, it is omitted in the drawing for the sake of brevity.

However, even in this type of press-fit type crystal vibrator, if the difference between the outer diameter of the stem 1 and the inner diameter of the cap 6 is large, the frictional force between the stem 1 and the cap 6 is large, and the glass 3 Cracks sometimes occurred.

As a result of various experiments, the inventor has determined that the cause of cracks in the glass 3 is that tensile stress acts on the glass 3 during press-fitting, and cracks occur in the glass 3, which has a lower tensile stress resistance than its compressive stress resistance. I came to the conclusion that.

Next, the reason will be explained in detail.

FIG. 2 is a cross-sectional view during press-fitting to explain the conventional press-fitting method for the crystal vibrator shown in FIG.
The same parts as in the figures are given the same reference numerals. 7
is a press-fit type, and the tip surface 7a that contacts and presses the lower end surface of the metal outer ring 2 is a flat surface. Here, the outer diameter φ1 of the stem 1 is equal to the cap 6.
It is formed to be slightly larger than the inner diameter φ2 of. Further, the upper edge 2a of the metal outer ring 2 is chamfered. Next, the press-fitting method will be described. First, the cap 6 is fixed using a fixing jig (not shown), and the stem 1 is brought into contact with the opening thereof. As mentioned above, the upper edge 2a of the metal outer ring 2 is chamfered, so only this upper edge 2a fits into the opening, but due to the relationship φ1>φ2, the stem 1 will not fit inside the cap 6 any further. It doesn't fit in. Subsequently, a force F1 is applied to the press-fitting mold 7 to press-fit the stem 1 into the cap 6. At this time, cap 6
The lower end 6a of the stem 1 is slightly pushed outward and deformed, and the portion of the stem 1 that is press-fitted into the cap 6 is subjected to a compressive stress of F2 by the cap 6. Of course, the force F1 applied to the press-fit mold 7 is set to a magnitude that overcomes the frictional force proportional to the compressive stress. However, stem 1
In the lower part of , expulsion stress F3 in the direction of the arrow shown
receive. For this reason, the glass 3 is subjected to tensile stress, and it is thought that a crack will occur. If a crack occurs in the glass 3, the airtightness of the container will be lost, and the characteristics of the crystal oscillator 5 will deteriorate. .

Therefore, the main object of the present invention is to provide a press-fitting method that does not cause cracks in the glass constituting the stem when press-fitting a stem made of an airtight terminal into a metal cap.

To summarize this invention, the outer diameter of the press-fitting mold is made larger than the outer diameter of the airtight terminal, the tip surface thereof is formed into a concave tapered surface, and the airtight terminal is press-fitted while applying compressive stress to the unpressed-fitted portion. It is characterized by

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 3 shows a cross-sectional view during press-fit coating of the first embodiment in which the present invention is applied to press-fit the crystal vibrator shown in FIG. In the figure, the same parts as in FIGS. 1 and 2 are given the same reference numerals, and their explanations will be omitted. The feature of this embodiment is that the front end surface 71 of the press-fit mold 70 is formed into a concave tapered surface, as is clear from the enlarged view of the section A along the dashed-dotted line. When such a press-fitting die 70 is used, the press-fitting die 7
When the stem 1 is press-fitted into the cap 6 by applying force F1 to
On the other hand, the unpress-fitted part of the stem 1 is inserted into the press-fit mold 7.
The glass 3 constituting the stem 1 is also subjected to compressive stress F4 due to the tapered surface 71 of 0.0, and the occurrence of cracks in the glass 3 is significantly reduced.

Example A metal outer ring 2 made of iron with an outer diameter of 1.7 mmφ, an inner diameter of 1.3 mmφ, and a height of 1.0 mm is fitted with a Kovar metal outer ring 2 with an outer diameter of 0.2 mmφ and a length of 8.5 mm through a borosilicate glass 3. The stem 1 consists of an airtight terminal made by airtightly sealing the lead wires 4 at intervals of 0.7 mm, and the inner diameter is 1.6 mm.
mmφ, and the outer diameter is 1.9 mmφ when press-fitting into the nickel silver cap 6, the outer peripheral surface of the metal outer ring 2 and the cap 6
When a Pb-Sn alloy with a thickness of 10μ was coated on the inner surface of each opening and press-fitted using a press-fitting die 70 with a tapered surface 71 having an inclination angle of 1.5°, cracks in the glass 3 occurred. None of them were found.

On the other hand, when the same stem 1 and cap 6 as described above are press-fitted using a press-fitting die 7 whose tip end surface 7a is a flat surface, as shown in FIG. A crack occurred on glass 3.

FIG. 4 shows a sectional view of the second embodiment of the present invention during press-fitting. The feature of this embodiment is the dashed line B
As is clear from the enlarged view of the section, the tip end surface 71 of the press-fitting die 70 that presses the stem 1 is made into a concave tapered surface, and the lower end edge 2b of the metal outer ring 2 constituting the stem 1 is also provided with a tapered surface. That's what happened. Even in this case, compressive stress is applied to the unpress-fitted portion of the stem 1 and therefore to the glass 3, and the occurrence of cracks in the glass 3 can be prevented.

Although the above embodiments have been described in terms of containers for crystal resonators, they can also be applied to containers for other electronic components such as semiconductor devices. Further, the stem 1 can be applied not only to a glass hermetic terminal in which a lead wire 4 is sealed to a metal outer ring 2 through a glass 3, but also to a ceramic hermetic terminal in which a lead wire is brazed to a ceramic substrate.

As described above, in this invention, the tip end surface of the press-fitting mold is formed into a concave tapered surface, and the airtight terminal is press-fitted while applying compressive stress to the unpress-fitted part. Compressive stress is applied to the insulating material such as, which has the effect of eliminating the occurrence of cracks.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of a crystal oscillator, FIG. 2 is a sectional view of the crystal oscillator shown in FIG. 1 during press-fitting by a conventional press-fitting method, and FIGS. FIG. 3 is a cross-sectional view during press-fitting by the press-fitting method. 1...Hermetic terminal (stem), 2...Metal outer ring,
3...Glass, 4...Lead wire, 5...Crystal resonator, 6...Press-fitted body (cap), 70...Press-fit type, 71...Tip surface.

Claims (1)

[Scope of Claims] 1. A method for press-fitting an airtight terminal into an opening of a press-fitted body using a press-fitting die, the outer diameter of the press-fitting die being larger than the outer diameter of the airtight terminal, and the tip surface thereof being formed into a concave tapered surface. A press-fitting method characterized in that the airtight terminal is press-fitted while applying compressive stress to the unpressed-fitted portion of the airtight terminal. 2. The press-fitting method according to claim 1, wherein the press-fitted body is a metal cap.