JP2014057131A - Two-stage joined crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-stage joined crystal oscillator integrated with a crystal unit by using an IC unit having its enclosure reduced in cost.SOLUTION: An IC unit 200 incorporates, in an IC container 21 separate from a crystal container 10 of a crystal unit 100, an IC chip 25 having integrated therein an oscillation circuit for producing a prescribed frequency signal by output of a crystal resonator 2 and a temperature control circuit for controlling the temperature characteristic thereof to stabilize the oscillation frequency, and is integrated with the crystal unit 100 by stacking one on top of another. An electrode pad 24 is formed on a wiring pattern 23 formed on the inner face of an IC container bottom wall layer 21a which is one board and die-bonded to the inner face of an IC container ceiling wall layer 21c which is the other board, and a solder bump 26 is connected to the electrode pad 24 of the wiring pattern 23 provided on the IC container bottom wall layer 21a side, in which way one board is mounted on the other board.

Description

  The present invention relates to a crystal oscillator, and more particularly to a small and low cost two-stage junction oscillator in which a crystal unit and an IC unit are integrated vertically.

  Since the oscillator for surface mounting is small and lightweight, it is built in a portable electronic device such as a mobile phone as a frequency and time reference source. One of these is a unit that consists of a container containing a crystal unit (hereinafter referred to as a crystal unit), and an oscillation that oscillates a predetermined frequency signal at the output of the crystal unit on a container or substrate that is separate from the crystal unit. A so-called two-stage junction type in which a circuit (hereinafter referred to as an IC unit) containing an IC chip that integrates a circuit and a temperature control circuit that stabilizes the oscillation frequency by controlling its temperature characteristics is joined up and down. is there.

  FIGS. 5A and 5B are diagrams for explaining a conventional example of a two-stage junction crystal oscillator. FIG. 5A is a cross-sectional view, and FIG. 5B is along the line XX ′ in FIG. The top view cut | disconnected and seen from the crystal unit side is shown. This two-stage junction type crystal oscillator (hereinafter also simply referred to as a crystal oscillator) 1 includes a crystal unit 100 and an IC unit 200. The crystal unit 100 includes a crystal resonator 2 fixed to the recess of the crystal container 10 formed of a ceramic sheet in which a crystal container bottom wall layer 1a and a crystal container frame wall layer 1b are stacked to form a recess.

  A crystal holding terminal 4 is formed on the bottom surface (inner bottom surface) of the concave portion of the crystal container 10. The crystal holding terminal 4 is connected to the crystal side connection electrode 8 through a crystal wiring 7 a formed in the castellation 7 on the side surface of the crystal unit 100. In the quartz resonator 2, excitation electrodes (not shown) are formed on both the front and back surfaces of the crystal piece, and each extension portion is extended to both sides of one end portion of the crystal piece to form an extraction electrode (not shown). This extraction electrode is fixed to the crystal holding terminal 4 with a conductive adhesive 3. The crystal container 10 containing the crystal resonator 2 is sealed by fixing a metal cover 6 to the opening end surface of the recess through a metal ring 5 by welding or the like.

  The IC unit 200 includes an IC container 21 formed of a ceramic sheet having a recess formed by stacking an IC container bottom wall layer 21a and an IC container frame wall layer 21b. A wiring pattern 23 is formed on the inner bottom surface of the IC container 21. The IC chip 25 is mounted on the electrode pad 24 of the wiring pattern 23 by being fixed with solder bumps 26. A part or the whole of the periphery of the IC chip 25 is filled with an underfill 27 preferably made of an epoxy resin to secure the IC chip 25 securely and mechanically. A plurality (four in this case) of mounting terminals 22 are provided on the outer bottom surface (mounting surface) of the bottom wall layer 21a. The wiring pattern 23 and the mounting terminal 22 are electrically connected by a via hole (not shown) penetrating the bottom wall layer 21a.

  The crystal unit 100 and the IC unit 200 are the crystal side connection electrode 8 formed on the outer surface of the bottom wall layer 1a of the crystal unit 100 and the IC side connection terminal formed on the opening end (frame wall layer 21b) of the IC unit 200. It is connected and fixed to the solder 28 by solder 9. As a result, the crystal unit 100 and the IC unit 200 are integrated to form the crystal oscillator 1. Desirably, the crystal unit 100 excluding the crystal side connection electrode 8 and the IC side connection terminal 28 and the IC unit 200 are bonded with an appropriate adhesive such as an epoxy resin to seal a recess containing the IC chip 25. To do.

  FIG. 6 is a cross-sectional view similar to FIG. 5 (a) for explaining another conventional example of a two-stage junction type crystal oscillator. In the crystal oscillator of FIG. 5 described above, the crystal unit 100 and the IC unit 200 both use a container made of a ceramic sheet. However, since the ceramic sheet is formed by a firing process, a manufacturing facility equipped with the firing furnace is required, and the manufacturing process is complicated, so that there is a limit to reducing the product price.

  In the crystal oscillator shown in FIG. 6, the crystal unit 100 is one in which a crystal resonator is housed in a crystal container 10 formed of the same ceramic sheet as in FIG. 5 and sealed with a metal cover 6. However, the IC container 21 constituting the IC unit 200 includes an IC container bottom wall layer 21a, an IC container frame wall layer 21b, and an IC container ceiling wall layer 21c formed of a glass epoxy sheet obtained at a lower cost than a ceramic sheet. 5 differs from the crystal oscillator of FIG. 5 in that the IC chip 25 is sealed. The IC chip 25 is mounted with the solder bumps 26 fixed to the electrode pads 24 of the wiring pattern 23 patterned on the inner wall surface of the IC container bottom wall layer 21a.

  A plan view taken along line XX ′ in FIG. 6 and viewed from the crystal unit 100 side is the same as FIG. 5B, but the IC chip 25 in FIG. 5 is covered with a ceiling wall 21c, and the ceiling wall It differs from FIG. 5 in having IC side connection terminals 28 at the four corners of 21c. Some of the crystal oscillators of this conventional type are filled with an underfill 27 around the entire periphery of the IC chip 25.

  In general, in this type of crystal oscillator, a ceramic sheet container having a large rigidity is used as the container of the crystal unit in order to ensure stable frequency oscillation of the crystal resonator. However, since the IC unit container is not required to be as rigid as the crystal unit, a glass epoxy sheet can be used for the IC unit container.

  In addition, Patent Document 1, Patent Document 2, and the like can be cited as materials disclosing this type of prior art.

JP 2011-166241 A JP 2007-274455 A

  In the conventional example described with reference to FIG. 5, both the quartz container and the IC container are formed by firing a ceramic sheet at a high temperature, so that there is a limit to the reduction in manufacturing cost. Even if the structure shown in FIG. 6 is adopted to prevent this, a significant cost reduction effect cannot be expected.

  The IC unit described with reference to FIG. 6 is formed with a so-called glass epoxy sheet with a built-in component, and is manufactured using a dedicated board-equipped facility. Therefore, even if the glass epoxy sheet is a low-priced substrate material compared to the ceramic sheet, it is not always possible to obtain a crystal oscillator at a low cost in view of the installation cost of manufacturing equipment.

  An object of the present invention is to provide a two-stage junction type crystal oscillator integrated with a crystal unit using an IC unit having a low cost casing or container.

In order to achieve the above object, the present invention has the following configuration. That is,
A crystal unit composed of a container containing a crystal oscillator, an oscillation circuit that oscillates a predetermined frequency signal by the output of the crystal oscillator on a container or substrate separate from the crystal unit, and controls its temperature characteristics to oscillate A two-stage junction crystal oscillator that integrates an IC unit with an IC chip that integrates a temperature control circuit that stabilizes the frequency,
The crystal unit is formed on the inner bottom surface formed by a crystal container formed by a substrate having a recess made of a laminate of a bottom wall layer and a frame wall layer of a ceramic sheet, and a bottom wall layer of the recess of the crystal container. A crystal resonator housed with one edge fixed to the holding terminal, a metal cover fixed to cover the opening of the recess, and a crystal side connection electrode provided at a plurality of corners of the outer bottom surface of the bottom wall layer And
The IC unit is inserted into a plurality of opposing corners of two single-layer substrates of a glass epoxy sheet to form a plurality of solder balls forming an IC chip housing space, and the IC chip housing space accommodates the IC unit. An IC chip and a mounting terminal provided at a portion of the other single-layer substrate facing the crystal-side connection electrode of the crystal unit and provided at a plurality of corners on the outer surface of the one single-layer substrate. ,
The crystal side connection electrode of the crystal unit and the IC side connection terminal of the IC unit were connected by soldering and integrated.

  A wiring pattern is formed on a surface of one of the two single-layer substrates facing the other single-layer substrate, and the IC chip is provided on the wiring pattern of the one single-layer substrate. It is characterized by being bonded to the terminal by die bonding.

  A wiring pattern is formed on the surface of the other single-layer substrate facing the one single-layer substrate of the two single-layer substrates, and the IC chip is provided on the wiring pattern of the other single-layer substrate. It is characterized by being bonded to the terminal by die bonding.

  The IC chip housing space is filled with an underfill for embedding the IC chip.

The quartz unit has a second bottom wall layer and a second frame wall layer on an outer bottom surface of the bottom wall layer of the crystal unit, and the IC unit has a wiring pattern of one glass epoxy sheet on which a wiring pattern is formed. Bonded to the provided electrode pad by die bonding,
The upper electrode provided on the opening end face of the second frame wall layer of the crystal unit and the lower electrode provided on the edge of the one glass epoxy sheet of the IC unit are fixed by soldering, and the crystal The unit and the IC unit may be integrated. As the other configuration, the configuration using the two single-layer substrates described above can be applied.

  By adopting the configuration of the present invention described in the claims, it is possible to obtain a two-stage junction type crystal oscillator which is integrated with a crystal unit using a low-cost IC unit and which is reduced in cost as a whole.

It is explanatory drawing of Example 1 of the two-stage junction type crystal oscillator based on this invention. It is sectional drawing similar to the said Example explaining Example 2 of the two-stage junction type crystal oscillator based on this invention. It is sectional drawing similar to each said Example explaining Example 3 of the two-stage junction type crystal oscillator based on this invention. 1 is a schematic circuit diagram of a constant temperature oscillator integrated on an IC chip of a two-stage junction crystal oscillator according to the present invention. FIG. It is a figure explaining a prior art example of a two-stage junction type crystal oscillator. It is a figure explaining the other conventional example of a two-stage junction type crystal oscillator.

  FIG. 1 is an explanatory diagram of a first embodiment of a two-stage junction type crystal oscillator according to the present invention. FIG. 1 (a) is a cross-sectional view, and FIG. 1 (b) is an XX ′ line in FIG. It is the top view seen from the crystal unit side along the sheet | seat. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  In FIG. 1, the two-stage junction type crystal oscillator 1 includes a crystal unit 100 and an IC unit 200. The crystal unit 100 is composed of a container 10 (crystal container) that houses the crystal resonator 2. The crystal unit 100 is formed of a crystal container 10 formed of a substrate having a recess made of a laminate of ceramic sheets composed of a bottom wall layer 1 a and a frame wall layer 1 b, and a bottom wall layer 1 a of the recess of the crystal container 10. A quartz crystal resonator 2 housed in a quartz crystal holding terminal 4 provided on the inner bottom surface with one edge fixed by a conductive adhesive 3, a metal cover 6 fixed to cover the opening of the recess, and the bottom It is comprised with the crystal side connection electrode 8 provided in the some corner | angular part of the outer bottom face of the wall layer 1a.

  The opening end surface of the frame wall layer 1 b constituting the recess is hermetically sealed with the metal cover 6 via the metal ring 5. The crystal holding terminal 4 is connected to the crystal side connection electrode 8 by a crystal wiring 7 a formed on a castellation 7 provided on the side surface of the crystal container 10. The crystal-side connection electrode 8 is connected to a wiring pattern 23 that connects the IC chip 25 through solder 9, which will be described later, an IC-side connection terminal 28, and a solder ball 30.

  The IC unit 200 includes an oscillation circuit that oscillates a predetermined frequency signal by the output of the crystal resonator 2 in a container 21 separate from the crystal unit 100, and a temperature control circuit that stabilizes the oscillation frequency by controlling the temperature characteristics thereof. Is integrated with the crystal unit 100 so as to be stacked one above the other. An electrode pad 24 is formed on the wiring pattern 23 formed on the inner surface of the IC container bottom wall layer 21a, die bonded to the inner surface of the IC container ceiling wall layer 21c, and the electrode pad of the wiring pattern 23 on the IC container bottom wall layer 21a side. 24 is mounted with solder bumps 26 connected thereto.

  The IC unit 200 is inserted into a plurality of opposing corners of the IC container bottom wall layer 21a and the IC container ceiling wall layer 21c, which are two single-layer substrates formed of a glass epoxy sheet, to provide an IC chip accommodation space. A plurality of solder balls 30 are formed. The solder ball 30 is formed by winding a solder layer 30b around a metal or resin core 30a. The IC chip 25 is accommodated in the IC chip accommodation space. The solder ball 30 is formed between the lower electrode 31 and the upper electrode 32 provided on the IC container bottom wall layer 21a which is one substrate of the single layer and the IC container ceiling wall layer 21c which is the other substrate, with the core 30a. The IC chip accommodating space is secured and fixed by the solder film 30b.

  Then, at the portion of the IC container ceiling wall layer 21c, which is the other single-layer substrate, facing the crystal-side connection electrode 8 of the crystal unit 100, the outer surface of the IC container bottom wall layer 21a, which is the one single-layer substrate. IC side connection terminals 28 are provided at a plurality of corners. The crystal side connection electrode 8 and the IC side connection terminal 28 are connected by solder 9. As shown in FIG. 1B, the IC chip 25 accommodated in the IC unit 200 is filled with an underfill 27 using a resin such as an epoxy resin, so that the IC chip 25 is securely fixed and two steps. The overall rigidity of the junction type crystal oscillator is improved.

  When the mounting terminals 22 are provided at the four corners of the outer surface of the IC container bottom wall layer 21a which is the one single-layer substrate, and the two-stage junction type crystal oscillator of this embodiment is mounted on the substrate of the mounting target device. The surface of the mounting terminal 22 is fixed to an electrode terminal of a circuit or the like provided on the substrate by surface mounting.

  According to the two-stage junction type crystal oscillator of the first embodiment, a glass epoxy sheet is used for the IC container 21 that is the casing of the IC unit 200, thereby providing a two-stage junction type crystal oscillator that is reduced in cost as a whole. be able to.

  FIG. 2 is a cross-sectional view similar to the previous embodiment for explaining the second embodiment of the two-stage junction type crystal oscillator according to the present invention, and the same reference numerals are given to the same functional parts. The difference in configuration from the first embodiment is that the IC chip 25 housed in the IC unit 200 is die-bonded to the IC container ceiling wall layer 21c side, which is the other single-layer substrate, and is provided on the wiring pattern 23 on the inner surface. 24, IC chip solder bumps 26 are connected. Since the other configuration overlaps with the description of the first embodiment, the description thereof will be omitted.

  Thus, in the second embodiment, the IC unit 200 is configured by arranging the IC container bottom wall layer 21a and the IC container ceiling wall layer 21c in parallel and accommodating the IC chip 25 in the space between them. The distance between the IC container bottom wall layer 21a and the IC container ceiling wall layer 21c is set by the solder balls 30 inserted at the four corners facing each other.

  According to the two-stage junction type crystal oscillator of the second embodiment, in addition to the cost reduction by using the glass epoxy sheet for the IC container 21 which is the casing of the IC unit 200, it is mounted on the electrode terminal of the substrate of the mounting target device. This has the effect of suppressing the possibility of remelting of the electrode pads 24 of the wiring pattern 23 and the solder bumps 26 of the IC chip 25 in the reflow process for connecting the terminals 22.

  FIG. 3 is a cross-sectional view similar to each of the above-described embodiments for explaining the third embodiment of the two-stage junction type crystal oscillator according to the present invention. The difference from the first and second embodiments is that a second bottom wall layer 1d and a second frame wall layer 1e are provided on the outer surface of the bottom wall layer 1a of the container (crystal container) 10 of the crystal unit 100. As an IC unit 200 that accommodates the IC chip 25, an IC container bottom wall layer 21a that is a substrate of one glass epoxy sheet, a second bottom wall layer 1d and a second frame wall layer 1e of the crystal unit 100, It is a point composed of.

  The IC chip 25 is mounted by fixing the solder bumps 26 to the electrode pads 24 of the wiring pattern 23 formed on the inner surface of the IC container bottom wall layer 21a. A crystal side connection terminal 8 connected to the excitation electrode of the crystal resonator 2 is formed on the opening end surface of the second frame wall layer 1 e provided on the outer surface of the crystal container bottom wall layer 1 a of the crystal unit 100. On the other hand, a lower electrode 31 is provided around the same surface as the IC chip mounting surface of the IC container bottom wall layer 21a, which is a substrate constituting the IC unit 200, and is fixed by the crystal side connection terminal 8 and the solder 9. ing.

  It is desirable to fill the IC chip accommodation space of the IC unit 200 with an underfill 27 to ensure the fixing of the IC chip and improve the rigidity of the entire oscillator. In FIG. 3, the IC chip 25 is mounted on the inner surface of the IC container bottom wall layer 21a. However, the wiring pattern 23 is provided on the second bottom wall layer 1d side of the crystal unit 100, and the IC chip 25 is provided here. It can also be set as the structure to mount.

  According to the two-stage junction type crystal oscillator of the third embodiment, since the glass epoxy sheet is used for the IC container that is the casing of the IC unit 200, the cost is reduced by the above-described embodiments, and solder balls are not used. This process reduction also has the effect of further reducing the cost.

  FIG. 4 is a schematic circuit diagram of a constant temperature oscillator integrated on the IC chip of the two-stage junction crystal oscillator of the present invention. The constant temperature oscillator includes an oscillation circuit 12 having a crystal resonator 2 and an oscillating unit 11, and a temperature control circuit 14 for controlling the operating temperature of the crystal resonator 2 to be constant. The oscillation circuit 12 is, for example, a Colpitts type, and here is a voltage control type in which the voltage variable capacitance element 13 is connected to the crystal resonator 2.

  The temperature control circuit 14 includes an operational amplifier 15f and a transistor 15g. The operational amplifier 15f compares the reference voltage Vr set by the voltage dividing resistors 15c and 15d with the temperature detection voltage Vt by the voltage dividing resistor 15b, one of which is a temperature sensitive element such as the thermistor 15a, and uses the difference as a control voltage to control the transistor 15g Output to. The transistor 15g increases or decreases the collector current according to the control voltage from the operational amplifier 15f, and controls the amount of heat generated by the chip resistor (heating resistor) 15e as a heating resistor. Thereby, the operating temperature of the crystal unit 2 is controlled to be constant.

  The present invention is not limited to a crystal oscillator, but can be applied to an oscillator using another piezoelectric vibrator or a composite microelectronic component having a similar structure.

1. ・ Two-stage crystal oscillator 1a ・ ・ Crystal container bottom wall layer 1b ・ ・ Crystal container frame wall layer 2. ・ Crystal resonator 3. ・ Conductive adhesive 4. ・ Crystal holding terminal 5. ・ Metal ring 6・ ・ Metal cover 7 ・ ・ Castellation 7a ・ ・ Crystal wiring 8 ・ ・ Crystal-side connection electrode 9 ・ ・ Solder 10 ・ ・ Crystal container 11 ・ ・ Oscillation unit 12 ・ ・ Oscillation circuit 13 ・ ・ Voltage variable capacitor 14 ・ ・Temperature control circuit 15a..Thermistor 15b, 15c, 15d..Voltage resistance 15e..Heat generation resistor 15f..Operational amplifier 15g..Transistor 21..IC container 21a..IC container bottom wall layer 21b..IC container frame wall Layer 21c ··· IC container ceiling wall layer 22 · · Mounting terminal 23 · · Wiring pattern 24 · · Electrode pad 25 · · IC chip 26 · · Solder bump 27 · · Underfill 28 · · IC side Continued terminal 30 ... solder balls 31 ... lower electrode 32 ... upper electrode 100 .. crystal unit 200 ... IC unit Vc · control voltage input Vout ... oscillation output terminal Vcc · operating voltage input terminal.

Claims (4)

A crystal unit composed of a container containing a crystal resonator, an oscillation circuit that oscillates a predetermined frequency signal by the output of the crystal resonator prepared separately from the crystal unit, and its temperature characteristics to control the oscillation frequency A two-stage junction type crystal oscillator in which an IC unit equipped with an IC chip on which a temperature control circuit to be stabilized is integrated is vertically stacked,
The crystal unit includes a crystal container formed by a substrate having a recess made of a laminate of a bottom wall layer and a frame wall layer of a ceramic sheet, and a crystal provided on an inner bottom surface formed by a bottom wall layer of the recess of the crystal container. A crystal resonator housed with one edge fixed to the holding terminal, a metal cover fixed to cover the opening of the recess, and a crystal side connection electrode provided at a plurality of corners of the outer bottom surface of the bottom wall layer And consists of
The IC unit includes a plurality of solder balls that are inserted into a plurality of opposing corners of two single-layer substrates of glass epoxy sheets to form an IC chip housing space, and the IC chip housing space accommodates the IC unit. An IC chip, an IC-side connection terminal connected to a wiring pattern provided on the one single-layer substrate, provided on a portion of the other single-layer substrate facing the crystal-side connection electrode of the crystal unit; It is composed of mounting terminals provided at a plurality of corners on the outer surface of one single-layer substrate,
A two-stage junction type crystal oscillator, wherein the crystal side connection electrode of the crystal unit and the IC side connection terminal of the IC unit are connected and integrated by soldering. In claim 1,
A wiring pattern is formed on a surface of one of the two single-layer substrates facing the other single-layer substrate, and the IC chip is provided on the wiring pattern of the one single-layer substrate. A two-stage bonded crystal oscillator characterized in that it is bonded to a terminal of an electrode pad by die bonding. In claim 1,
A wiring pattern is formed on the surface of the other single-layer substrate facing the one single-layer substrate of the two single-layer substrates, and the IC chip is provided on the wiring pattern of the other single-layer substrate. A two-stage bonded crystal oscillator characterized in that it is bonded to a terminal of an electrode pad by die bonding. In any one of Claims 1 thru | or 3,
2. A two-stage junction type crystal oscillator, wherein the IC chip housing space is filled with an underfill for embedding the IC chip.

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