JP2015177245A - Surface mounted crystal oscillator with thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electrical short-circuiting from being incurred by contact of a bottom face of a metal base with a metal pin by holding a solder or a conductive filler with which the inside of a top face side two-stage counterbore part is filled, within the top face side two-stage counterbore part by reflow.SOLUTION: In a surface mounted crystal oscillator with a thermostat, a metal base 3 including a plurality of stand-offs 6 on a bottom face is mounted while being engaged to metal pins 5 erected in a plurality of through-holes 2d provided on a base substrate 2, and a crystal vibrator is disposed on the metal base 3 and covered by a metal cover 4, thereby providing a sealed structure. Around the metal pins 5 at a ground face side and a top face side of the base substrate 2, a top face side two-stage counterbore part 10 and a ground face side two-stage counterbore part 11 are formed each of which is formed from a two-stage counterbore part including a first-stage counterbore part and a second-stage counterbore part with a larger diameter than the first-stage counterbore part. The first-stage counterbore part, the second-stage counterbore part and gaps between the through-holes 2d and the metal pins 5 are filled with a solder or a conductive resin 10d, and the metal pins 5 are fixed in the through-holes 2d on the base substrate 2.

Description

  The present invention relates to a crystal oscillator with a thermostatic chamber (OCXO), and more particularly to a crystal oscillator with a thermostatic chamber that is a surface mount type soldered lead-pin type OCXO to a base substrate.

  The crystal oscillator with a thermostatic chamber (OCXO) has the highest precision with a structure in which the crystal unit is placed in a thermostatic chamber (oven), and the crystal unit is heated by a heater to keep the crystal unit at a constant temperature. Crystal oscillator.

  In this type of conventional crystal oscillator with a thermostatic chamber (OCXO), a circuit board made of glass epoxy resin is attached to the upper end of a ground pin standing on the glass epoxy board, and a metal plate is attached to the lower surface of the crystal board via a heat dissipation sheet. Furthermore, a crystal resonator is attached to the lower surface of the metal plate. Further, electronic components such as circuit elements are mounted on the upper surface of the circuit board, and terminals of the crystal resonator are provided so as to protrude. Further, a metal cover is placed on a glass epoxy substrate, and the metal cover is soldered and sealed at several locations on the outer peripheral edge of the glass epoxy substrate (see Patent Document 1).

  However, in this type of conventional crystal oscillator with a thermostatic chamber (OCXO), as described above, the oscillator parts are arranged on the glass epoxy substrate and the metal base is covered with the metal base, and then the metal base is covered. Since the metal cover is structured to be soldered and sealed at several locations on the outer peripheral edge thereof, it is not a completely sealed structure. For this reason, moisture penetrates into the crystal oscillator from the outer peripheral edge of the soldered metal cover, the circuit board itself made of glass epoxy resin passes through the moisture, and the frequency of the crystal oscillator changes due to moisture. Humidity affected the inside of the crystal oscillator, causing a change in the frequency of the crystal oscillator. For this reason, there is a problem that this type of surface-mounted crystal oscillator cannot sufficiently meet the high customer demand for frequency stability.

  Therefore, in order to solve such a problem, in the conventional surface mount type crystal oscillator with a thermostatic bath, the plurality of through holes 2d provided in the base substrate 2 are erected as shown in FIGS. A metal base 3 provided with a plurality of stand-offs 6 on the bottom surface is engaged with and placed on the metal pin 5, a circuit board is attached to the upper end of the metal pin 5, and a quartz crystal is attached to the circuit board via a heating element. A vibrator is disposed, and the metal base 4 is covered with a metal cover 4 so that the crystal vibrator has a sealed structure.

  Then, as shown in FIG. 7, on the bottom surface of the base substrate 2, a second-stage counterbore part 11 including a first-stage counterbore part 11 b and a second-stage counterbore part 11 a having a larger diameter is formed. Solder or conductive resin 10d is filled in the first-stage counterbore portion 11b formed around the metal pin 5 inserted into the through hole 2d and the gap between the through hole 2d and the metal pin 5. The metal pin 5 is fixed to the through hole 2d (see Patent Document 2).

JP 2010-154227 A JP 2012-85266 A

  However, even in such a conventional example, as shown in FIG. 5, the gap between the metal base of the OCXO and the base substrate is only the height of the stand-off provided on the bottom surface of the metal base. When the OCXO metal pins are inserted into a plurality of through holes provided in the base substrate with solder and the joints are fixed to the base substrate with solder, these metal pins and the metal base are electrically connected via the solder. There was a risk of short circuit.

  In order to solve the above-described problems, a surface mount type quartz crystal oscillator with a thermostatic bath according to the present invention has a metal base in which a plurality of stand-offs are provided on a bottom surface of a metal pin standing in a plurality of through holes provided in a base substrate. In the crystal oscillator with a surface-mounted thermostatic chamber in which a quartz resonator is disposed on the metal base and a metal cover is covered to form a sealed structure, the metal on the ground side and the top surface side of the base substrate Around the pin, the top surface side two-step counterbore portion and the ground-side two-step counterbore portion formed of the first-stage counterbore portion and the second-stage counterbore portion made of the second-stage counterbore portion having a diameter larger than this, The first-stage counterbore part, the second-stage counterbore part, and a gap between the through hole and the metal pin are filled with solder or conductive resin, and the metal pin is fixed to the through hole. To do.

  The crystal oscillator with a surface-mounted thermostat according to the present invention is characterized in that the copper plating portion is formed so as to cover the inner peripheral surface of the through hole and the first step counterbore portion.

  Furthermore, the surface mount type quartz crystal oscillator with a thermostatic bath of the present invention is characterized in that the copper plating part is formed so as to cover the inner peripheral surface of the through hole and the first step counterbore part.

  Furthermore, in the crystal oscillator with a surface-mounted thermostat according to the present invention, the first step and the second step counterbore are circular counterbore portions formed around the through hole. Features.

  In the crystal oscillator with a surface-mounted thermostat according to the present invention, the first step and the second step counterbore portions are grooves having an oval shape in plan view and communicated with the through hole.

  Solder or conductive filler filled from the top surface of the base substrate to the top surface side two-step counterbore due to reflow may remain in the counterbore, causing the bottom surface of the metal base and the metal pin to come into contact and causing an electrical short circuit. Disappear.

It is a side view of the Example of the surface mount-type thermostat crystal oscillator of this invention. It is the bottom view which looked at the crystal oscillator with a surface mount type thermostatic bath of the present invention shown in FIG. 1 from the ground (bottom) direction of the base substrate. It is a top view of the top | upper surface (upper surface) of the base substrate seen from the ZZ arrow direction shown in FIG. It is an expanded sectional view of the part which provided the two step counterbore part shown by A arrow in FIG. 1 in both the top | upper surface of a base substrate, and the ground. It is a side view of the conventional surface-mounted thermostat crystal oscillator. FIG. 6 is a bottom view of the conventional surface-mounted thermostat crystal oscillator shown in FIG. 5 viewed from the ground (bottom) direction of the base substrate. FIG. 6 is an enlarged cross-sectional view of a portion where a two-step counterbore portion shown in FIG.

  Embodiments of a crystal oscillator with a surface-mounted thermostat according to the present invention will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, a surface-mounted thermostat crystal oscillator 1 according to the present invention is configured by laminating and bonding an upper base substrate 2a, a middle base substrate 2b, and a lower base substrate 2c made of glass epoxy resin. A metal pin (lead pin) 5 is inserted and erected through a plurality of through holes 2d penetrating the base substrate 2 in the vertical direction and a plurality of through holes 2d penetrating the metal base 3 through a seal member.

  Then, the metal base 3 is placed on the upper surface of the base substrate 2 via, for example, four stand-offs (protrusions) 6 provided so as to protrude from the bottom surface of the metal base 3. A circuit board made of glass epoxy resin having a circuit element or the like provided on the upper surface thereof is attached to the upper end portion.

  Further, by providing a stand-off 6 projecting on the bottom surface of the metal base 3, as shown in FIG. 1, between the bottom surface of the metal base 3 and the base substrate 2 top surface (upper surface) made of glass epoxy resin, A gap g is formed, and heat generated inside the OCXO is difficult to escape to the base substrate 2. Further, on the bottom surface of the circuit board, a crystal resonator (not shown) containing a crystal vibrating piece is disposed via a heating element, and on the side surface of each side of the base substrate 2, a set substrate of the customer is provided. End face through-holes 7a and 7b are formed which are soldered to each other.

  Then, the metal cover 4 is placed from above the crystal resonator and placed on the outer peripheral edge of the upper surface of the metal base 3, and the outer peripheral edge is sealed by soldering or resistance welding so that the inside of the metal cover 4 is sealed. To do.

  Here, in the crystal oscillator 1 with a surface-mounted thermostat according to the embodiment of the present invention, as shown in FIG. 4 which is an enlarged partial sectional view of the portion A in FIG. Formed as a two-step counterbore portion 10 and a ground-side two-step counterbore portion 11, a metal pin (terminal) 5 is inserted into a through hole 2 d formed in the base substrate 2, and the metal pin 5 is soldered or electrically conductive adhesive 10 d. The base substrate 2 is fixed to the through hole 2d.

  With this configuration, even if the tip 5a of the metal pin (terminal) 5 and the solder or conductive adhesive 10d protrude from the ground (bottom surface) 2a of the base substrate 2, the surface mounting of the present invention onto the mounting substrate at the customer site When mounting the crystal oscillator with the thermostatic oven, these members do not come into contact with the mounting substrate.

  That is, as shown in FIG. 4, in the crystal oscillator with a surface-mounted thermostatic chamber of the present invention, a first-stage counterbore portion in a circular shape in plan view is formed on the top surface (upper surface) of the upper base substrate 2a of the base substrate 2 by a counterbore drill or the like. 10a and a second-stage counterbore part 10b having a diameter larger than that of the first-stage counterbore part 10a are formed around the through hole 2d formed in the base substrate 2 to constitute the top surface side two-stage counterbore part 10.

  Similarly, in the crystal oscillator with surface mounted thermostatic chamber of the present invention, as shown in FIG. 4, the top surface (upper surface) of the lower layer base substrate 2c of the base substrate 2 is countersunk with a first step counterbore by a counterbore drill or the like. The ground-side two-stage counterbore part 11 is formed by forming a portion 11a and a second-stage counterbore part 11b having a diameter larger than that of the first-stage counterbore part 11a around the through hole 2d formed in the base substrate 2.

 Furthermore, the copper plating part 10c is formed in the inner surface of each 2nd step counterbore part 10b, 11b of the top | upper surface side two step counterbore part 10 and the ground side two step counterbore part 11, and the through-hole 2d.

  And the metal pin 5 is inserted and positioned in the inner diameter part of the copper plating part 10c formed in the inner peripheral surface of the through hole 2d, and the gap between the outer diameter part of the metal pin 5 and the inner diameter part of the copper plating part 10c. Next, the solder or the conductive adhesive 10d is reflowed from the top surface side of the base substrate 2.

  With this reflow, as shown in detail in FIG. 4, in the crystal oscillator with surface mounted thermostatic bath of the present invention, the solder or the conductive adhesive 10 d is applied to the top surface side two-step counterbore portion 10 and the ground side two-step counterbore portion 11. The metal pin 5 is fixed in the through hole 2d. However, the solder or conductive filler 10d filled in the top surface side two-step counterbore part 10 remains, and the bottom surface of the metal base 4 and the metal pin 5 do not come into contact with each other to cause an electrical short circuit.

  In addition, the counterbore part formed in the top | upper surface of the upper base substrate 2a of the base substrate 2 and the lower layer base substrate 2c is formed into a plurality of through-holes continuously in an oval shape as indicated by phantom lines in FIGS. You may straddle and form.

  And the front-end | tip of the metal pin 5 is mounted | worn with the apparatus for characteristic adjustment of the crystal oscillator 1 with a surface mount type thermostat, and the characteristic adjustment is performed. After the characteristic adjustment, the tip of the metal pin 5 is cut into a length that does not protrude from the lower layer base substrate 2c after passing through the base substrate 2 and a length that allows the base substrate 2 and the metal pin 4 to be joined. The tip 5a of the metal pin 5 is not projected from the ground (bottom surface) of the lower base substrate 2c of the base substrate 2 by bending it into an L shape.

  The crystal oscillator with surface-mounted thermostat according to the present invention is, for example, formed into a collective base material substrate by collecting 8 pieces and then cut with a dicing saw or the like to obtain a crystal oscillator with a surface-mounted thermostat. And

DESCRIPTION OF SYMBOLS 1 Surface mount type crystal oscillator with a thermostat 2 Base substrate 2a Upper layer base substrate 2b Middle layer base substrate 2c Lower layer base substrate 2d Through hole 3 Metal base 4 Metal cover 5 Lead pin 6 Stand-off 7a End surface through hole 7b End surface through hole 10 Top plate Side two-step counterbore part 11 Bottom plate side two-step counterbore part

Claims (4)

A metal base provided with a plurality of stand-offs on the bottom surface is engaged and placed on a metal pin standing in a plurality of through holes provided in the base substrate, and a crystal resonator is disposed on the metal base and a metal cover is covered. In a surface-mounted crystal oscillator with a thermostatic chamber that has a sealed structure,
The top surface side two-step counterbore portion composed of a first step counterbore portion and a second step counterbore portion having a larger diameter than the first step counterbore portion around the metal pins on the ground side and the top surface side of the base substrate. And a ground side two-step counterbore part, and the solder between the first stage counterbore part, the second stage counterbore part, and the gap between the through hole and the metal pin is filled with solder or conductive resin. The surface mount type crystal oscillator with a thermostatic bath, wherein the metal pin is fixed to the through hole.   The crystal oscillator with a surface-mounted thermostat according to claim 1, wherein a copper plating part is formed so as to cover an inner peripheral surface of the through hole and the first step counterbore part.   2. The surface-mount type thermostatic crystal according to claim 1, wherein the first-stage and second-stage counterbore parts are counterbore parts having a circular shape in plan view formed around the through hole. Oscillator.   2. The surface-mounted thermostat crystal oscillator according to claim 1, wherein the first-stage and second-stage counterbore portions are grooves having an oval shape in plan view that communicate with the through hole.

Images