JP6050153B2 - Surface mount type low profile crystal oscillator - Google Patents

Description

  The present invention relates to a surface-mount type crystal oscillator, and more particularly to a surface-mount type low-profile crystal oscillator in which a crystal resonator and an IC chip that constitutes an oscillation circuit together with the crystal resonator are accommodated in a recess of a container body. About.

  A surface-mounted crystal oscillator (hereinafter also referred to as a surface-mounted oscillator) is small and light, and is built in as a frequency and time reference source in portable electronic devices represented by, for example, mobile phones. As one of such devices, there is a surface mount oscillator in which a quartz crystal resonator and an IC chip are accommodated in parallel in a concave portion of a container body to further reduce the height. An IC chip integrates an oscillation circuit and an output circuit that constitute an oscillator together with a crystal resonator, and a temperature compensation circuit and a temperature control circuit depending on the type of the oscillator.

  In manufacturing such a crystal oscillator, a crystal resonator and an IC chip are mounted in a recess provided in the container body, and then the recess of the container body is sealed with a metal cover. The metal cover prevents fluctuations in ambient conditions of external temperature and humidity, dust intrusion, and the like, and shields the quartz vibrator from external electromagnetic waves to avoid a change in oscillation frequency.

  In manufacturing a crystal oscillator, there is a process of mounting a crystal resonator and an IC chip in a recess provided in a container body, and measuring the vibration characteristics of the crystal resonator after sealing the recess with a metal cover. Products that pass this measurement process are shipped as products.

  FIG. 4 is an explanatory view of a structural example of a conventional surface-mount type low-profile crystal oscillator. This low-profile quartz oscillator 100 has a flat box shape with a substantially rectangular plan view. 4A is a longitudinal sectional view of the container body, FIG. 4B is a perspective view for explaining the overall shape, and FIG. 4C is a bottom view as viewed from the mounting terminal side. The container body 1 in this example has a recess 9 formed by stacking two bottom wall layers 1a and 1b and a frame wall layer 1d that are rectangular in plan view. In addition, the number of lamination | stacking of a bottom wall layer and a frame wall layer is an example, and is not limited to what was illustrated.

  A crystal terminal 11 and an electrode pad 10 formed in a wiring pattern (not shown) are provided on the inner bottom surface of the recess 9. A crystal resonator 2 is mounted on the crystal terminal 11, and an IC chip 3 is mounted on the electrode pad 10. The crystal unit 2 has excitation electrodes formed by vapor deposition of metal or the like on both sides of a crystal piece (crystal blank), and an electrode extending from each of these excitation electrodes to one end of the crystal piece is a conductive adhesive 5. Thus, the crystal unit 11 is fixed to the crystal terminal 11. The IC chip 3 has a plurality of bumps 8 serving as output terminals mounted on electrode pads 10 arranged at corresponding positions on the bottom surface of the recess 9 by heat welding using solder or ultrasonic pressure welding.

  After mounting the crystal resonator 2 and the IC chip 3 in the recess 9 of the container body 1, the recess is sealed with a metal cover 7. Sealing of the metal cover 7 is performed by crimping and welding the metal cover 7 to the metal ring 6 provided on the opening end surface of the recess 9, that is, the end surface of the frame wall 1 d forming the recess 9. A metallized layer of a refractory metal (tungsten, molybdenum, etc.) is provided under the metal ring 6 (opening end face of the recess 9) (not shown).

  On the back surface (exposed surface) of the bottom wall 1b, there are a plurality (four in this case: 4a, 4b, 4c, 4d) of terminals for plane mounting (hereinafter also simply referred to as mounting terminals) 4. The electrical connection between the IC chip 3 and the mounting terminal 4 is made through an internal conductor pattern or via hole (not shown) provided on the ceramic sheet, or a notch (castellation) provided on the side wall surface of the container body 1. Done through conductors. In the illustrated example, connection conductors 18 formed at corner notches (corner castellations) 17 provided at the four corners of the bottom wall layer are used.

  After the recess 9 of the container body is sealed with the metal cover 7, the vibration characteristics of the crystal resonator 2 are measured. In the conventional crystal oscillator shown in FIG. 4, measurement is performed by applying a probe (probe) of an inspection apparatus to an inspection terminal 14 provided with a notch 12 on the side surface of the container body 1. The inspection terminal 14 to which the probe is applied is formed by plating or the like on a side notch (side castellation) 12 provided on the side wall of the container body 1 and is electrically connected to the crystal terminal 11. The measurement of the vibration characteristics is performed by pressing a probe from the lateral direction 1d of the frame wall to each of the inspection terminals 14 (see Patent Document 1).

  FIG. 5 is an explanatory diagram of another structural example of a conventional surface mount type low-profile crystal oscillator. In another conventional crystal oscillator shown in FIG. 5, the inspection terminal 14 of the crystal resonator 2 is provided on the bottom wall layer. A crystal terminal 11 of the crystal resonator 2 is connected by a via hole 13 penetrating the bottom wall layer. An electrode column is embedded in the via hole 13. In addition, since the surface mounting terminal 4 is provided on the same surface as the installation surface of the inspection terminal 14 in the bottom wall layer, a part of the bottom wall of the inspection terminal portion is removed to provide a recessed portion, and the bottom surface Is provided with a conductor layer for the inspection terminal 14. The probe in this case is brought into contact with the crystal oscillator from the bottom surface direction (see Patent Document 2).

JP 2010-141875 A Japanese Patent Laid-Open No. 08-307153

  In the former prior art shown in FIG. 4, the probe is pressed against the container body of the crystal oscillator from both sides in the lateral direction so that stable measurement is difficult and accurate test results are obtained. Difficult to get. Further, in the latter prior art shown in FIG. 5, since the recessed portion is provided in a part of the bottom wall where the inspection terminal is provided, the strength of the bottom wall is reduced, and the bottom wall layer is cracked by the contact of the probe. This causes damage and causes the entire container body to be vulnerable. This is particularly noticeable in a crystal oscillator or the like having a low profile but a large spread in the planar direction in which the crystal resonator and the IC chip according to the present invention are arranged in parallel.

  This kind of low-profile crystal oscillator is used not only for mounting on a circuit board as a discrete component, but also as a composite component by molding with other components at the customer after shipment. In some cases, an underfill resin is applied to protect peripheral components. If the conventional structure is simply provided with a recess in the bottom wall and the inspection terminals are arranged, the capacitance between the crystal terminals may change via these resins, and the oscillation frequency may shift.

  The object of the present invention is to avoid mechanical weakness of the container body due to the placement of the inspection terminal of the crystal resonator, stabilize the inspection operation of the crystal resonator during manufacture, and change the oscillation frequency depending on the use environment. An object of the present invention is to provide a highly reliable surface-mount type low-profile crystal oscillator that does not incur any problems.

  (1) A surface-mount type low-profile crystal oscillator according to the present invention is accommodated in a container body having a recess formed by laminating a bottom wall and a frame wall having a rectangular shape in a plan view made of ceramics, and the recess. A crystal resonator and an IC chip that is mounted in parallel with the crystal resonator on the bottom surface of the recess and integrates a circuit that constitutes an oscillation circuit together with the crystal resonator.

  (2) A plurality of metal covers that are provided on a mounting surface that is opposite to the metal cover that seals the concave portion and shields the crystal resonator from an external electromagnetic field, and the metal cover of the bottom wall that forms the container body. Mounting terminals.

(3) The concave portion is provided with a first region for mounting the crystal unit and a second region for mounting the IC chip.

(4) The bottom wall of the first region is formed thicker than the bottom wall of the second region.

(5) in the first region of the mounting surface, the inspection terminal of the crystal oscillator in the recess for the test terminals have a test terminal recess recessed from the mounting surface is provided.

(6) A thermosetting resin is filled and cured in the recess for the inspection terminal.

(7) The inspection terminal of the crystal resonator and the crystal terminal on which the crystal resonator is mounted are electrically connected by a via hole penetrating the bottom wall.

  (8) As the IC chip, a chip in which a temperature compensation circuit is integrated in addition to an oscillation circuit can be used.

  (9) It should be noted that the IC chip may be one in which various auxiliary circuits constituting a known crystal oscillator such as a temperature control circuit are integrated.

  (10) It goes without saying that the present invention can be variously modified without departing from the technical idea of the invention described in the claims.

  According to the surface-mounted crystal oscillator according to the present invention having the above-described configuration, mechanical vulnerability of the container body due to the arrangement of the inspection terminal of the crystal resonator is avoided, and the inspection operation of the crystal resonator is stable during manufacturing. Therefore, a highly reliable surface-mount type low-profile crystal oscillator that does not change the oscillation frequency depending on the use environment can be obtained.

It is a longitudinal cross-sectional view explaining the structure of one Example of the surface mount-type low-profile crystal oscillator based on this invention. It is a top view of the recessed part which has in the container main body explaining the structure of one Example of the surface mount type low-profile crystal oscillator based on this invention. It is a top view of the mounting surface of a container main body explaining the structure of one Example of the surface mount-type low-profile crystal oscillator based on this invention. It is explanatory drawing of one structural example of the conventional surface mount type low-profile crystal oscillator. It is explanatory drawing of the other structural example of the conventional surface mount type low-profile crystal oscillator.

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

  FIG. 1 is a longitudinal sectional view for explaining the structure of an embodiment of a surface-mounted low-profile oscillator according to the present invention. FIG. 2 is a plan view of a recess provided in the container body of FIG. FIG. 3 is a plan view of a mounting surface provided with mounting terminals for mounting the crystal oscillator of FIG. 1 on a circuit board of an applied device. Hereinafter, the surface mount type low profile oscillator is also simply referred to as a low profile oscillator. The low-profile oscillator 100 according to the present embodiment includes a crystal resonator 2 and a container body 1 including bottom walls 1a, 1b, 1c and a frame wall 1d made of a laminated ceramic sheet (green sheet) having a rectangular shape in plan view. The IC chips 3 are accommodated in parallel. In addition, the said number of lamination | stacking of a bottom wall or a frame wall is an example.

  The container body 1 has a recess 9 formed by laminating a frame wall on a bottom wall formed of a laminated ceramic sheet similar to the above-described conventional example. The recess 9 has a crystal resonator mounting area AR1 and an IC chip mounting area. AR2 is provided in parallel, and the crystal unit 2 and the IC chip 3 are accommodated side by side. In the present embodiment, the concave portion 9 of the container body 1 is further added to the crystal resonator mounting area AR1 of the bottom wall made up of the bottom walls 1a and 1b to raise the mounting space of the crystal resonator 2 to raise the crystal resonator 2 mounting space. The strength of the child mounting area AR1 is increased, and the height of the mounting space for the crystal resonator 2 is made smaller than the mounting space for the IC chip.

  That is, the bottom wall constituting the mounting space for the crystal resonator 2 is formed thicker than the mounting space for the IC chip 3. The crystal resonator 2 is fixed with a conductive adhesive 5 to a pair of crystal terminals 11 provided on the surface of the bottom wall 1c. A test terminal recess 16 for providing a test terminal is formed in the bottom wall 1b on the mounting surface side. An inspection terminal 14 is provided on the bottom wall 1 a on the mounting surface exposed to the inspection terminal recess 16. The crystal terminal 11 is connected to the inspection terminal 14 through an electrode column 13a filling a via hole 13 provided on the bottom wall.

  After the inspection terminal 14 is inspected and measured using the probe of the vibration characteristic measuring device of the crystal resonator 2, the inspection terminal recess 16 is filled with a thermosetting protective resin 15 suitable for epoxy resin, The frequency fluctuation after mounting which can occur when the mechanical strength of the wall is secured and the measurement terminal 14 is exposed is suppressed. The thermosetting protective resin 15 is completely cured by heating during reflow during mounting.

  The container body 1 is formed by firing a laminate of ceramic sheets. The mounting terminals 4 (4a, 4b, 4c, 4d) are formed by forming a metallized layer by sintering a metal (a refractory metal such as tungsten: W or molybdenum: Mo) at each corner of the bottom wall 1b, and then by electroplating or the like. A nickel (Ni) film and a gold (Au) film are sequentially plated.

  The crystal resonator 2 is a crystal terminal formed on the bottom surface of the concave portion 9 of the container body 1 with the excitation electrodes formed on both main surfaces of a crystal piece (crystal blank) extending, for example, on both sides of one end thereof. 11 is fixed. For this fixing, for example, a conductive adhesive 5 in which a conductive filler such as silver particles is mixed in an epoxy resin is used. The metal cover 7 is hermetically sealed by joining the metal cover 7 to the metal ring 6 provided on the opening end face of the frame wall 1d by seam welding. Although not shown, a refractory metal metallization layer is formed on the base of the metal ring 6 on the opening end face. Such a structure is the same as the conventional one described above.

  In addition, the space between the IC chip 3 and the recess 9 area AR2 can be filled with a so-called underfill resin. This resin can also be applied as a protective resin to the back surface of the IC chip 3 (the surface on the metal cover 7 side). Further, instead of the resin on the back surface, a protective resin film can be provided in advance on the back surface of the IC chip 3.

  By adopting the configuration of the present embodiment, mechanical vulnerability of the container main body due to the arrangement of the inspection terminal of the crystal resonator on the bottom wall is avoided. In addition, since the inspection terminal is provided on the bottom wall, the inspection operation of the crystal unit is facilitated, and stable and accurate inspection is possible. Furthermore, a highly reliable surface-mount type low-profile crystal oscillator that does not change the oscillation frequency depending on the use environment can be obtained.

  The present invention is not limited to the low-profile crystal oscillator described in the above embodiment, but can also be applied to piezoelectric parts having the same structure, MEMS, and other microelectronic parts for planar mounting.

  1 .. Container body, 2 .. Crystal resonator, 3 .. IC chip, 4 .. Mounting terminal, 5 .. Conductive adhesive, 6 .. Metal ring, 7 .. Metal cover (lid), 8 ..Bump, 9 ..Recess, 10 ..Electrode pad, 11 ..Crystal terminal, 12 ..Side cut-out, 13 ..Via hole, 13 a ..Electrode pillar, 14 .. Inspection terminal, 15. , 16 .. Inspection terminal recess, 17 .. Corner notch, 18 .. Connection conductor, 100 .. Surface mount type low profile oscillator.

Claims (3)

A container main body having a recess formed by stacking a bottom wall and a frame wall having a rectangular shape in a plan view made of ceramics, a crystal resonator housed in the recess, and a bottom surface of the recess in parallel with the crystal resonator An IC chip that is mounted and integrated with a circuit that constitutes an oscillation circuit together with the crystal resonator, a metal cover that seals the concave portion and shields the crystal resonator from an external electromagnetic field, and the container body is formed. A surface mount type low-profile crystal oscillator comprising a plurality of mounting terminals provided on a mounting surface opposite to the metal cover of the bottom wall,
The recess is provided with a first region for mounting the crystal resonator and a second region for mounting the IC chip,
The bottom wall of the first region is formed thicker than the bottom wall of the second region,
In the first region of the mounting surface, and the inspection terminal of the crystal oscillator to the test terminal for the recess has a test terminal recess recessed from the mounting surface is provided,
A surface-mount type low-profile crystal oscillator, wherein the inspection terminal recess is filled and cured with a thermosetting resin. In claim 1,
A surface-mount type low-profile crystal oscillator, wherein the inspection terminal of the crystal resonator and the crystal terminal on which the crystal resonator is mounted are electrically connected by a via hole penetrating the bottom wall. In claim 1,
The surface-mount type crystal oscillator according to claim 1, wherein the IC chip includes a temperature compensation circuit.

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