JP2002290188A - Surface-mounted crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent solder plating from adhering onto the front surface of a sealed tube, in a part which is not coated with a mold resin, even when it is subjected to solder plating after mold resin molding in a surface mounted crystal oscillator which uses a cylinder type crystal oscillator. SOLUTION: An oxidized membrane is formed on the front surface of the sealed tube of the resin-coated cylinder type crystal oscillator, so as to prevent adhesion of solder plating from sticking thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type crystal unit used for information equipment such as a portable telephone and a computer.

[0002]

2. Description of the Related Art A quartz oscillator is a resonator utilizing the piezoelectric effect of quartz, and is used in many fields because it is a stable oscillation source unique to quartz.
Used in mobile phones and the like.

[0003] In recent years, a crystal resonator has been required to have a surface mounting type in order to increase the substrate mounting density like other electronic parts, and the lead type has begun to change from a lead type to a surface mounting type.

[0004] In order to enable soldering in a reflow furnace or the like, a surface mount type crystal resonator having improved heat resistance has been put to practical use. FIG. 1 is an exploded perspective view of a crystal resonator used for a surface mount type crystal resonator. 1 is a sealing tube, 2
Is an airtight terminal, 3 is a lead, 4 is a crystal piece, and 5 is an electrode formed on the crystal piece. The crystal unit is fixed to an inner lead 3a of a lead in which a crystal piece is embedded in an airtight terminal.
This is a cylinder-type crystal resonator which is completed by press-fitting a hermetic terminal to which a crystal piece is fixed in a sealing tube.

Since the reflow furnace is exposed to a high-temperature atmosphere of 240 to 260 ° C., the heat resistance of the cylinder-type crystal unit used for the surface-mount type crystal unit must be improved. FIG. 2 is a sectional view of the hermetic terminal. The hermetic terminal 2 is composed of the outer peripheral metal portion 6, glass 7, lead 3, and plating 8 applied to the outer peripheral metal portion 6, but the plating 8 is made of high-temperature solder so as to be exposed to the high-temperature atmosphere. (For example, lead: balance = 9: 1) is used. On the other hand, in order to obtain heat resistance, the sealing tube is generally plated with nickel on the surface of the material.

FIG. 3 shows a state in which a lead of the above-mentioned cylinder type quartz resonator is connected to a lead frame 9 and a mold resin 10 is formed.
FIG. 1 is a perspective view of a surface-mount type quartz crystal resonator according to the present invention, which is covered by the present invention.

[0007] With respect to the surface mount type crystal unit, there is an increasing demand for downsizing and thinning, and the thickness of the mold resin covering the crystal unit is reduced, so that the sealing tube is formed from the mold resin. There is a problem of exposure.

[0008]

FIG. 4 shows a surface mount type crystal oscillator after molding the mold resin by holding the seal tube with a pin so as not to expose the seal tube from the mold resin in the surface mount type crystal unit. The top view, front view, and A-
It is represented by a cross-sectional view of the portion A '. AA 'part is
4 shows a portion that is held down by a pin because the sealing tube is not exposed from the mold resin. In order to improve the solderability of the surface mount type crystal oscillator during reflow, after molding the mold resin, solder plating 11 is performed on the lead frame, but at the same time, the seal is not covered with the mold resin. Solder plating will also be applied to the surface of the stop pipe.

When the surface mount type crystal unit shown in FIG. 4 is soldered to a printed circuit board, the solder plating is melted and peeled off from the surface of the sealing tube due to heat during soldering, and falls on the printed circuit board to fall on the printed circuit board. In some cases, short shots occurred.

[0010]

An oxide film is formed on the surface of the sealing tube to prevent solder plating on the surface of the sealing tube which is not covered with the mold resin in the surface mount type crystal unit. I do.

[0011]

FIG. 5 shows a cylinder according to the present invention.
It is sectional drawing of the sealing tube used for a type crystal resonator. Nickel plating 12 is applied to the surface of the sealing tube, and an oxide film 13 is formed thereon. The oxide film 13 is formed by performing a heat treatment on the sealing tube at a heat treatment temperature of 200 ° C. or higher and a heat treatment time of 72 hours in a vacuum furnace at a pressure of 133 to 66.5 Pa.

FIG. 6 is a top view, a front view, and a cross-sectional view taken along the line AA 'of the internal structure of the surface mount type crystal unit of the present invention. A lead of a cylinder-type quartz oscillator in which the sealing tube of FIG. 5 is press-fitted and sealed to a hermetic terminal to which a quartz piece is fixed is connected to a lead frame for establishing electrical continuity. Mold with resin. When molding mold resin,
The sealing tube of the cylinder type crystal unit is held down by pins to prevent the surface of the mold resin from being exposed. Further, after molding the mold resin, the lead frame is plated with solder. Since an oxide film is formed on the surface of the sealing tube of the cylinder-type quartz resonator, there is no conductivity.
No solder plating is applied to the surface of the sealing tube not covered with the solder resin.

[0013]

According to the present invention, in a surface mount type crystal unit using a cylinder type crystal unit, after molding a mold resin, the surface of the sealing tube which is not covered with the mold resin even after solder plating is performed. It was possible to prevent solder plating. Since there is no solder plating on the surface of the sealing tube, short-circuit failure between components on the printed circuit board does not occur.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a crystal unit.

FIG. 2 is a sectional view of an airtight terminal.

FIG. 3 is a perspective view of a surface-mount type crystal unit according to the present invention.

FIG. 4 is a top view (A), a front view (B), and a cross-sectional view taken along the line AA ′ of a surface-mount type crystal unit in which a sealing tube is suppressed by a pin so as not to expose the crystal unit from a mold resin. Figure

FIG. 5 is a sectional view of a sealing tube according to the present invention.

6A is a top view, FIG. 6B is a front view, and FIG. 6B is a cross-sectional view taken along the line AA ′ of the surface-mounted crystal resonator according to the present invention.

[Explanation of symbols]

 1. Seal tube 2. Airtight terminal 3. Lead 3a. 3. Inner lead Crystal blank 5. Electrode 6. Outer peripheral metal part 7. Glass 8. Plated part 9. Lead frame 10. Mold resin 11. Solder plating 12. Nickel plating 13. Oxide film

Claims (1)

[Claims] 1. A crystal resonator is held in a hermetic terminal provided with two or more leads, and a crystal resonator formed by press-fitting a sealing tube into said hermetic terminal is electrically connected to said lead. The lead frame connected to the sealing tube is coated with a resin, and then plated with solder, and the surface of the sealing tube is heated to 200 ° C. or more in a vacuum furnace having a pressure of 133 to 66.5 Pa. A surface-mount type crystal unit characterized by forming an oxide film by heat treatment.