JPH0249729Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to stems, and is particularly suitable for stems for crystal resonators and surface acoustic wave elements that are mounted on printed circuit boards etc. by a predetermined distance and insulated from the printed circuits. It is.

Conventional technology Quartz crystal resonators and surface acoustic wave devices are generally formed using a metal case, and as a stem of the metal case, a straight lead wire is passed through a glass through a hole in a metal substrate and is hermetically insulated. A hermetically sealed terminal is used. When installing such a crystal resonator or surface acoustic wave device on a printed circuit board, etc., the bottom surface of the metal substrate must be raised above the top surface of the printed circuit board to prevent the printed circuit formed on the top surface of the printed circuit board and the metal substrate from being shot. It is necessary.

Stems conventionally used for this purpose have the structure shown in FIGS. 2 and 3. FIG. 2 is a plan view, and FIG. 3 is a front sectional view taken along the line - in FIG. In the figure, reference numeral 1 denotes a rectangular metal substrate made of iron, low carbon steel, 42 alloy, etc., which has a flange 2 on the periphery, through holes 3 near the four corners, and the inner side of each through hole 3. It also has a through hole 4. A straight lead wire 6 made of iron-nickel alloy or the like is hermetically and insulatively sealed to each of the through holes 3 through a glass 5 such as soda lime glass or soda barium glass. A glass 7 similar to that described above is hermetically sealed to each of the metal substrates 4 so that its lower end protrudes from the lower surface of the metal substrate 1 by a predetermined distance h. These glasses 7
is called a standoff.

According to the above structure, the lower surface of the metal substrate 1 can be mounted by floating the lower surface of the printed circuit board 8 by a predetermined distance h from the upper surface of the printed circuit board 8 indicated by the two-dot chain line.

Problems to be Solved by the Invention However, if the metal substrate 1 is simply lifted from the printed circuit formed on the printed circuit board 8, there is no problem with the above structure, but the recent trend toward high-density mounting of printed circuit boards As a result, it has become necessary to lift the metal substrate off the chip parts etc. fixed on the printed circuit. For this reason, glass 7
It has become necessary to increase the protrusion dimension H from the bottom surface of the metal substrate 1, but due to the surface tension of the glass 7, the protrusion can only be made around the radial dimension of the through hole 4. Increasing the inner diameter of the stem not only reduces the effective area of the stem, but also increases the amount of glass used, and in order to secure a predetermined effective area, the entire stem becomes larger. Furthermore, if the amount of glass 7 is increased and this protrusion dimension h is forcibly increased, cracks will occur at the base of the metal substrate 1 of the glass 7 due to the difference in expansion coefficients between the metal substrate 1 and the glass 7, causing the glass to crack. There was a problem that 7 was easily damaged.

Means for Solving the Problems In order to solve the above-mentioned problems, this invention forms a flat part flush with the lower surface of the metal substrate in a portion of the stand-off adjacent to the lower end of the through hole of the metal substrate. It is characterized by the fact that

Effect According to the above means, by forming a horizontal surface part in the part adjacent to the lower end of the through hole of the metal substrate in the stand-off, compared to the case where the molten glass becomes hemispherical due to the surface tension in the natural state. As a result, it is possible to increase the protrusion dimension of the standoff by an amount corresponding to the amount of glass in the lower part of the flat part, and even if this protrusion dimension is increased, due to the existence of the flat part, There is no steep change in compressive stress in the glass, and no breakage of stand-offs due to glass cracks.

Embodiment Hereinafter, an embodiment of this invention will be described with reference to the drawings.

Figure 1 is a front sectional view corresponding to Figure 3, and is the same as Figure 3 except for the following points, so the same parts are given the same reference numerals and their explanation will be omitted. . The difference from FIG. 3 is that a standoff 9 is formed by airtightly sealing glass inside the through hole 4.
However, the metallic substrate 1 has a flat portion 9a in a portion adjacent to the lower end of the through hole 4, and has a stepped shape in which a protruding portion 9b is formed in the center of the flat portion 9a. In the one-dot chain line circle, a two-dot chain line 10 indicates a virtual line when the glass is made into a hemispherical shape by surface tension in its natural state, and it protrudes by a dimension h' corresponding to the amount of glass in the lower part of the plane part 9a. The protruding dimension of the portion 9b can be increased. For example, when the inner diameter of the through hole 4 is 1.4 mm, when the width of the flat portion 9a is set to 1.0 mm, the protrusion dimension H of the protrusion 9b can be set to 0.8 mm. On the other hand, in the case of the conventional stand-off 7 which does not have a flat part, when the protrusion dimension was set to 0.8 mm, cracks occurred and the stand-off broke. Also, in order to make the protrusion dimension of standoff 7 0.8mm,
It was found that the inner diameter of the through hole 4 needed to be 1.8 mm or more.

Effects of the invention According to this invention, by forming a flat part flush with the lower surface of the metal substrate in the part of the stand-off adjacent to the lower end of the through hole of the metal substrate,
With the same inner diameter of the through hole and the same amount of glass as before,
The protrusion dimension can be increased, and breakage due to stand-off cracks does not occur.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a stem according to an embodiment of this invention, and an enlarged sectional view of the main parts thereof is also shown within a chain line circle. Figure 2 is a plan view of a conventional stem.
FIG. 3 is a front sectional view taken along the - line in FIG. 2. 1...Metal substrate, 3, 4...Through hole, 5...Glass, 6...Lead wire, 9...Stand-off, 9
a...Plane part, 9b...Protrusion part.

Claims (1)

[Claims for Utility Model Registration] A lead wire that is hermetically and insulatedly sealed through glass to some of the holes in a metal substrate having multiple holes, and a lead wire that is hermetically and insulatedly sealed to some of the holes in a metal substrate that has a plurality of holes, and that the lower end of the lead wire is sealed with glass in other through holes. A stem having a standoff formed by airtight sealing so as to protrude from the lower surface of the metal substrate, wherein a portion of the standoff adjacent to the lower end of the through hole of the metal substrate is provided with a surface of the lower surface of the metal substrate. A stem characterized by forming a uniform flat part.