JP4354744B2 - Surface mount crystal oscillator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface-mount crystal oscillator (hereinafter referred to as a surface-mount oscillator) that is an industrial technical field, and more particularly to a surface-mount oscillator that facilitates injection of a protective resin for an IC chip by face-down bonding.
[0002]
[Prior art]
BACKGROUND OF THE INVENTION Surface-mounted oscillators are small and light, and are particularly used as frequency and time reference sources for portable devices. In recent years, further miniaturization has progressed, and for example, 4 × 2.5 mm has emerged.
[0003]
(Example of Prior Art) FIG. 4 is a diagram of a surface mount oscillator for explaining one example of the prior art.
The surface-mount oscillator is fixed to the container body 1 having a cross-section H structure having recesses on both main surfaces, a crystal piece 3 housed in one recess and hermetically sealed by a cover 2, and face-down bonding to the other recess. It consists of an IC chip 4 in which an oscillation circuit is integrated. Reference numeral 5 denotes a conductive adhesive.
[0004]
In face-down bonding, bumps 6 such as gold are provided on an IC terminal (not shown) of the IC chip 4 and are fixed to the circuit terminal on the bottom of the recess by ultrasonic thermocompression bonding. Usually, a protective resin 7 is injected between the IC chip 4 and the bottom surface of the recess, and the circuit surface including the IC terminal of the IC chip 4 is shielded from the outside to protect (so-called underfill, Patent Documents 1 and 2). ). In these cases, the tip of the nozzle 8 is inserted into the gap between the IC chip 4 and the inner wall of the recess, approaches the recess bottom, and the protective resin 7 is injected.
[0005]
[Problems to be solved by the invention]
(Problem of the prior art) However, in the crystal oscillator configured as described above, as the miniaturization progresses, the gap between the IC chip 4 and the inner wall of the recess becomes smaller. For this reason, as shown in FIG. 5, the tip of the nozzle 8 does not enter the gap. And the protective resin 7 was apply | coated on the surface of the IC chip 4, and there existed a problem which made formation of an underfill difficult.
[0006]
That is, with the progress of miniaturization, the application amount of the protective resin 7 is reduced, and for example, the discharge amount is once from the nozzle 8. Then, for example, as shown in FIG. 6, a circular protective resin 7 is discharged from the nozzle 8. On the other hand, when the gap between the IC chip 4 and the inner wall of the concave portion is reduced, the circular protective resin 7 adheres to the end surface of the IC chip 4 and is taken into the surface by surface tension or the like.
[0007]
In other words, the protective resin 7 cannot be taken in because the front end side of the protective resin 7 does not reach the bottom surface. Therefore, there is a problem that the underfill cannot be formed without entering the gap.
[0008]
An object of the present invention is to provide a surface mount oscillator capable of forming an underfill by facilitating injection of a protective resin.
[0009]
[Patent Document 1]
JP 2003-110363 A [Patent Document 2]
Japanese Patent Laid-Open No. 11-308052
[Means for Solving the Problems]
According to a first aspect of the present invention, a rectangular IC chip in which an oscillation circuit is integrated is fixed to a bottom surface of a concave part of a container body having a rectangular concave part by face-down bonding using a bump, and the inner wall of the concave part of the container body wherein by injecting protective resin from the gap between the outer peripheral side surface of the IC chip and, wherein the fixing surface of the IC chip by injecting a protective resin between the bottom surface of the recess Ri name, height of the IC chip is the recess In the surface-mounted crystal oscillator having a depth within a range, only the IC chip is fixed to the bottom surface of the recess , and at least one surface of the inner wall of the recess is provided with an arc-shaped step that is lower than the height of the IC chip. And Thereby, the distance between the nozzle tip and the horizontal surface of the step approaches, and the protective resin adheres to the step portion. Accordingly, the protective resin is injected through the step portion to form an underfill.
[0011]
According to the second aspect of the present invention, the container main body has recesses on both main surfaces, a crystal piece is accommodated in one recess, and the IC chip is fixed to the other recess. Make it concrete.
[0012]
According to the third aspect of the present invention, the container body is a mounting substrate formed by bonding a crystal unit containing a crystal piece and a back surface of the crystal unit and fixing the IC chip in a recess. Similarly to the above, the aspect of the surface mount oscillator is made concrete.
[0013]
【Example】
FIG. 1 is a diagram of a surface mount oscillator for explaining an embodiment of the present invention. 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.
[0014]
In the surface mount oscillator, the crystal piece 3 is fixed to one recess of the container body 1 having the H structure as described above by the conductive adhesive 5, and the IC chip 4 is fixed to the other recess by face-down bonding. And here, a level | step difference is provided in the both end side used as the length direction of the other recessed part. The step is formed by increasing the frame width on the bottom surface side and maintaining the surface side as before, increasing the number of layers. The horizontal surface of the step is set to a position lower than the height of the IC chip 4.
[0015]
With such a configuration, the tip of the nozzle 8 and the horizontal surface of the step approach each other, and the tip of the circular protective resin 7 adheres more to the step than the end surface of the IC chip 4. Therefore, the protective resin 7 is taken into the stepped portion and injected into the bottom surface of the IC through the side surface of the IC by a capillary phenomenon or the like to form an underfill.
[0016]
[Other matters]
In the above embodiment, the level difference is simply provided. For example, as shown in FIG. 2, a groove 9 may be provided at the lower level of the level difference so that the protective resin 7 can be easily drawn into the inner bottom surface by capillary action. Further, as shown in FIG. 2, the step may be arcuate, or may be only one end side in the length direction (not shown) or the width direction. In short, a step having an area equal to or larger than the outer dimension of the nozzle 8 ( Any plane can be used.
[0017]
Further, although the container body 1 has a cross-sectional H structure having recesses on both main surfaces, naturally, even when the mounting substrate 10 containing the IC chip 4 and the crystal unit 11 are joined as shown in FIG. Applicable. In this case, any of the closed surface and the opening surface of the mounting substrate 10 can be applied to the back surface of the crystal unit 11. Basically, the present invention can be applied to the case where the IC chip 4 is accommodated in the recess and underfill is required.
[0018]
【The invention's effect】
According to the present invention, a rectangular IC chip in which an oscillation circuit is integrated is fixed to a bottom surface of a concave part of a container body having a rectangular concave part by face-down bonding using a bump, and the inner wall of the concave part of the container body and the IC chip by injecting protective resin from the gap between the outer peripheral side surface of the IC chip Ri name by injecting a protective resin between the fixation surface and the recess bottom surface of the height of the IC chip is within the depth of the recess In the surface-mounted crystal oscillator, only the IC chip is fixed to the bottom surface of the recess, and an arc-shaped step lower than the height of the IC chip is provided on at least one surface of the inner wall of the recess . It is possible to provide a surface mount oscillator that can facilitate injection and form an underfill.
[Brief description of the drawings]
FIGS. 1A and 1B are views of a surface-mount oscillator for explaining an embodiment of the present invention, in which FIG. 1A is a cross-sectional view, and FIG. 1B is a plan view of the other concave portion.
FIG. 2 is a view of a container body for explaining another embodiment of the present invention.
FIG. 3 is an assembly cross-sectional view of a surface mount oscillator for explaining another application example of the invention.
FIG. 4 is a cross-sectional view of a surface mount oscillator for explaining a conventional example.
FIG. 5 is a cross-sectional view of a surface mount oscillator for explaining a conventional example.
FIG. 6 is a view of a protective resin discharged from a nozzle for explaining a conventional example.
[Explanation of symbols]
1 container body, 2 cover, 3 crystal piece, 4 IC chip, 5 conductive adhesive, 6 bump, 7 protective resin, 8 nozzle, 9 groove, 10 mounting substrate, 11 crystal resonator.

Claims (3)

A rectangular IC chip in which an oscillation circuit is integrated is fixed to a bottom surface of a concave part of a container body having a rectangular concave part by face-down bonding using a bump, and an inner wall of the concave part of the container body and an outer peripheral side surface of the IC chip, by injecting protective resin from the gap, the Ri sticking surface of the IC chip and greens by injecting a protective resin between the recess bottom surface, surface mounting height of the IC chip is within the depth of the recess In the crystal oscillator, only the IC chip is fixed to the bottom surface of the recess, and an arc-shaped step which is lower than the height of the IC chip is provided on at least one surface of the inner wall of the recess. .   2. The surface mount crystal oscillator according to claim 1, wherein the container body has recesses on both main surfaces, a crystal piece is accommodated in one recess, and the IC chip is fixed to the other recess.   2. The surface-mount crystal oscillator according to claim 1, wherein the container main body includes a crystal resonator containing a crystal piece and a mounting substrate bonded to the back surface of the crystal resonator and fixing the IC chip in the recess.

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