JP5150220B2 - Crystal oscillator for surface mounting - Google Patents

Description

  The present invention relates to a surface mount crystal oscillator (hereinafter referred to as a surface mount oscillator), and more particularly to a surface mount oscillator having an IC chip protective resin.

(Background of the Invention)
Since the surface-mounted oscillator is small and light, it is built in a portable electronic device typified by a mobile phone as a reference source for frequency and time. One of these is a surface-mount oscillator having an H structure in which a container body is H-shaped, a crystal piece is accommodated in a recess on one main surface, and an IC chip is accommodated in a recess on the other main surface.

(Example of conventional technology)
FIG. 3 is a diagram of a surface-mount oscillator for explaining a conventional example, in which FIG. 3 (a) is a sectional view and FIG. 3 (b) is a bottom view.

  The surface-mount oscillator has the above-described H structure, and a crystal piece 2 and an IC chip 3 are accommodated in a container body 1 having recesses on both main surfaces. The container body 1 is made of a laminated ceramic having a rectangular shape in plan view, and has a bottom wall 1a and upper and lower frame walls 1 (bc), and has concave portions on both main surfaces. The lower frame wall 1c is formed by laminating two ceramics (about 200 μm in total) having a thickness of about 100 μm, for example.

  The opening end face (upper face of the frame wall) of the lower frame wall 1c has an external terminal 4 electrically connected to the IC chip 3. These are divided into individual container bodies 1 after laminating ceramic green sheets and firing them integrally. However, after the external terminal 4 is formed by integrally firing a base electrode (W or Mo), Ni and Au films are sequentially plated by electroplating or the like.

  The crystal piece 2 has excitation electrodes (not shown) on both main surfaces, and extends extraction electrodes on both sides of one end, for example. Then, the conductive adhesive 5 is fixed to a crystal terminal (not shown) on the bottom surface of the recess on one main surface of the container body 1. Then, after adjusting the vibration frequency (oscillation frequency) of the crystal resonator, a metal cover 7 is joined to the metal ring 6 provided on the opening end face by seam welding, for example, and hermetically sealed.

  Thereafter, the vibration characteristics of the crystal resonator are measured by an inspection terminal (not shown) provided on the container body 1 to eliminate defective products, and then the IC chip 3 is accommodated on the other main surface of the container body 1. The IC chip 3 integrates at least an oscillation circuit and a temperature compensation mechanism as necessary. Then, the circuit functional surface (one main surface) provided with the IC terminals of the IC chip 3 is fixed to the bottom surface of the recess by, for example, ultrasonic thermocompression using the bumps 8 (so-called flip chip bonding).

  Normally, a protective resin 9 for protecting the circuit function surface of the IC chip 3 is injected into the bottom surface of the container body 1 from a nozzle (not shown). The protective resin 9 is heated and cured after being injected as a thermosetting type. Here, the protective resin 9 is injected by bringing the nozzle into contact with the ridge line portion of the other main surface of the IC chip 3.

  In this case, since the viscosity of the protective resin 9 is low, the protective resin 9 goes around the gap between the inner periphery of the lower frame wall 1 c and the outer periphery of the IC chip 3 and flows into the circuit function surface of the IC chip 3. Normally, the protective resin 9 is set lower than the height from the bottom wall 1 a of the IC chip 3. Then, due to the wettability of the protective resin 9, the protective resin 9 crawls up to the outer periphery of the IC chip 3 and the inner periphery of the lower frame wall 1 c and is cured. (So-called meniscus).

Since the protective resin 9 is injected by contacting the nozzle to the ridge line portion of the other main surface of the IC chip 3, a film having a thickness of, for example, about 10 μm is also formed on the other main surface of the IC chip 3. Even if the protective resin 9 does not flow into the circuit function surface of the IC chip 3, the circuit function surface can be protected if the outer peripheral side surface and the inner peripheral surface of the lower frame wall are filled.
JP 2000-49560 A

(Problems of conventional technology)
However, in the surface mount oscillator having the above configuration, when the protective resin 9 is injected into the concave portion of the other main surface of the container body 1 and thermally cured, the protective resin 9 is not only the inner peripheral surface of the lower frame wall but also the lower frame wall 1c. Crawling up to the top. Then, there is a problem that the film 10 is deposited on the surface of the external terminal 4 at the four corners to form the film 10 as shown in FIG. 4 (cross-sectional view).

  These cause some errors in the injection amount of the protective resin 9, so that the larger the injection amount (the surplus), the more remarkable the creeping. There is an error in the area of the lower frame wall 1c, and even if the injection amount is constant, the surplus is increased when the area is small. In these cases, when the surface mount oscillator is connected to the circuit terminal of the set substrate, the electrical connection becomes difficult due to the coating of the protective resin 9, which results in a defective product, and the productivity is reduced.

(Object of invention)
An object of the present invention is to provide a surface mount oscillator that prevents the adhesion of a protective resin to an external terminal and increases the productivity.

In the first embodiment of the present invention, a crystal piece is mounted and sealed in one main surface of a container body having a bottom wall and a frame wall made of a multilayer ceramic and having a rectangular shape in plan view. The surface has a concave portion provided with an external terminal at the four corners, the circuit function surface of the IC chip having the IC terminal is fixed to the concave portion of the other main surface, and the protective resin for the circuit function surface of the IC chip is In the crystal oscillator for surface mounting formed by filling the concave portion of the other main surface, the frame wall forming the concave portion of the other main surface of the container main body is a frame from the inner periphery to at least an intermediate region in the thickness direction of the four corner portions. It is set as the structure which has the notch part of the width direction.

  If it is such a structure, if the injection amount (excess part) of protective resin will increase, it will flow in the notch part provided in the intermediate | middle area | region of the frame wall. Therefore, creeping up to the opening end surface (upper surface) of the container body is suppressed to prevent adhesion to the external terminal. Thereby, defective products can be reduced and productivity can be increased.

In the second embodiment of the present invention, in the first embodiment, the height of the notch from the bottom wall is higher than the height of the surface opposite to the circuit function surface of the IC chip. Thus, if the protective resin is injected less than the height of the IC chip, even if the meniscus on the inner peripheral surface of the lower casing wall, so flowing into the cutout portion, the four corners provided with the external terminal It does not adhere to the upper surface of the frame wall.

In 3rd Embodiment of this invention, it has a recessed part in the 1st main surface of the said container main body in 1st Embodiment, and accommodates the said crystal piece and seal-encloses. Thus, the container body has an H-shaped cross-section structure having a recess on both major surfaces, a crystal piece in the recess of the one main surface, also to accommodate the IC chip in the recess of the other main surface.

(Embodiment)
FIG. 1 is a view of a surface-mount oscillator for explaining a first embodiment of the present invention. FIG. 1 (a) is a partially broken sectional view, FIG. 1 (b) is a bottom view, and FIG. It is the bottom view seen except the 2nd layer of a frame wall. 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.

  As described above, the surface-mount oscillator has an H structure, the crystal piece 2 is accommodated in a concave portion of one main surface of the container body 1 having a rectangular shape in plan view, a metal cover 7 is bonded and hermetically sealed, and the other main surface is sealed. The IC chip 3 is accommodated in the recess. External terminals 4 are provided at the four corners of the opening end face (upper surface of the frame wall) of the recess in the other main surface of the container body 1. The IC chip 3 is bonded to the circuit functional surface by ultrasonic thermocompression bonding using the bumps 8, and the protective resin 9 is injected.

  In this embodiment, the lower frame wall 1c that forms a recess on the other main surface of the container body has a notch 11 in the frame width direction from the inner periphery to at least an intermediate region in the thickness direction of the four corners where the external terminals 4 are provided. Have In this example, the lower frame wall 1c has a two-layer structure in which, for example, the first layer 1c1 and the second layer 1c2 are sequentially formed from the bottom wall 1a.

Then, rectangular cutouts 11 in the frame width direction are provided at the four corners of the first layer 1c1 of the lower frame wall 1c. The height h ₁ (thickness of the _first layer 1 c 1) of the notch 11 from the bottom wall 1 a is made higher than the height h ₂ of the IC chip 3.

  In such a configuration, the protective resin 9 is injected into the concave portion of the other main surface of the container body 1 from the ridge line portion of the other main surface of the IC chip 3 as described above, and particularly when the injection amount is large. It flows into the cutout 11 at the four corners. Therefore, the protective resin 9 is absorbed by the notch portion 11 to suppress the creeping up to the opening end surface of the recess (the upper surface of the lower frame wall).

  In particular, in the embodiment, since the height of the notch 11 is higher than the height of the IC chip 3, when the protective resin 9 is applied to a region lower than the height of the IC chip 2, the first layer of the lower frame wall 1c is formed. The scavenging protective resin 9 stops its progress on the back surface of the second layer 1c2, for example. Therefore, adhesion to the external terminals 4 at the four corners can be prevented and productivity can be improved.

(Other matters)
In the above embodiment, the lower frame wall 1c has a two-layer structure of the first layer 1c1 and the second layer 1c2. However, for example, as shown in FIG. Good. Further, for example, the cutout portion 11 can be provided by pressing the four corners of the bottom wall 1c without using a laminated structure (see FIG. 1).

  The container body 1 has a single H structure. However, for example, the container body 1 can be applied to a case where a concave mounting board is bonded to the lower surface of the surface mount vibrator. . In the case of the junction type, any case where the open end surface side or the closed surface side of the concave mounting substrate is connected to the lower surface of the surface mount vibrator can be applied.

  Furthermore, one main surface of the container main body 1 in which the crystal piece 2 is hermetically sealed is not a concave portion but can be similarly applied to a case where a concave cover is joined as a flat surface. In short, a surface having a concave portion for accommodating the IC chip 3 It can be applied to any mounted oscillator.

In FIG surface mount oscillator for explaining a first embodiment of the present invention, FIG. (A) is a cross-sectional view, and (b) shows a bottom view, the second layer in FIG (c) is a lower frame wall It is the bottom view seen except . It is sectional drawing of the surface mount oscillator explaining other embodiment of this invention. It is a figure of the surface mount oscillator explaining a prior art example, the figure (a) is a sectional view and the figure (b) is a bottom view. It is sectional drawing of the surface mount oscillator explaining the problem of a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 Crystal piece, 3 IC chip, 4 External terminal, 5 Metal ring, 6 Conductive adhesive, 7 Metal cover, 8 Bump, 9 Protective resin, 10 Film, 11 Notch

Claims (1)

Sealed sealed by mounting a crystal blank on a main surface of one of the recesses formed on the container body made of a rectangular shape in plan view the bottom wall made of laminated ceramic and a plurality of frame wall, the other main surface of the container body of external terminals provided at four corner portions, said fixing a circuit formation surface of the IC chip via the IC terminals to the other recess formed in the other main surface, wherein a protective resin to the circuit formation surface of the IC chip in the crystal oscillator for surface mounting formed by filling the other recess formed in the other main surface, a frame wall forming the recess of the other main surface of the container body, the four corners of the container body have a notch from the inner periphery are formed in the frame width direction of the recess of the other main surface in at least the middle region in the thickness direction, and the height from the bottom surface of the bottom wall of the notch, the IC chip From the height from the bottom surface of the bottom wall of the surface opposite to the circuit functional surface of A surface-mount crystal oscillator which is characterized in that formed high.