JP2001177055A - Surface mounting structure of ic, ceramic base and crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounting structure of an IC, a ceramic package and a crystal oscillator, using a conductive adhesive 8 wherein the electric short circuit is avoided to raise the connection strength. SOLUTION: In the surface mounting structure of an IC 2 which has a plurality of bumps 5 and fixed to a ceramic base 1, corresponding holes 11 are provided in the ceramic base and a conductive adhesive 8 is buried, inserted in the holes 11 and firmly fixed. In the ceramic base 1 which has the IC 12 having the plurality of bumps 5 and is mounted on the base surface, corresponding holes 11 are provided in the base surface. In the crystal oscillator composed of a ceramic package having a recess, the IC 2 having the plurality of surface mounted bumps 5 and a quartz piece 3 held on a side wall, corresponding holes 11 are provided in the bottom surface, the conductive adhesive 8 is buried, and the bumps 5 are inserted in the holes 11 and firmly fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an IC mounting structure,
The present invention relates to a ceramic container and a crystal oscillator as an industrial technical field, and particularly relates to a crystal oscillator having an increased IC fixing strength.

[0002]

2. Description of the Related Art Crystal oscillators are widely used as various frequency and time reference sources in various electronic devices including communication devices. In recent years, as the size of crystal oscillators has been reduced, the surface mounting (face-down bonding) of ICs has become widespread.

(Example of Prior Art) FIG. 5 is a sectional view of a crystal oscillator for explaining a conventional example. The crystal oscillator has a chip-shaped IC 2 and a crystal blank 3 housed in a ceramic base 1. The ceramic base 1 has a bottom wall 1a and first and second
A side wall 1 (bc) is laminated, and a concave portion and a step portion are formed on one surface side. Then, IC2 is surface-mounted on the bottom surface of the concave portion,
The crystal blank 3 is held on the step. Alternatively, the third and fourth frame walls 1 (de) are laminated on both surfaces of the bottom wall 1a to form recesses on both surfaces (FIG. 6). Then, the crystal blank 3 is held in the concave portion on one surface side, and the IC 2 is surface-mounted in the concave portion on the other main surface. Reference numeral 12 in the figure denotes a resin filled to protect the IC.

[0004] The IC 2 has a terminal electrode 4 on the surface, and forms a bump 5 made of gold or the like for surface mounting. In the surface mounting, the IC 2 is fixed to the circuit terminal 10 on the bottom surface by ultrasonic thermocompression or thermocompression. That is, while pressing the IC 2, ultrasonic waves and heat or only heat are applied, and the bumps 5 are crushed into an ellipse and joined. The crystal blank 3 has excitation electrodes 6 (ab) on both main surfaces, for example, extraction electrodes 7 (a) on both sides of one end.
b) is extended (FIG. 7), and one end is fixed to the step with the conductive adhesive 8 and held. The crystal blank 3 is hermetically sealed by, for example, sealing resin or glass or seam welding. Reference numeral 9 in the figure is a cover.

[0005]

However, in the crystal oscillator having the above-described structure, the height dimension can be reduced as compared with the wire bonding because of the surface mounting. Disadvantageous. In particular, when the concave portion is provided on both sides and the IC 2 is surface-mounted in the concave portion on the other main surface side, the bottom wall 1a of the ceramic base 1 is in a state of being floated in the air. Was making it difficult. Furthermore, in order to prevent damage due to the pressing force, the thickness must be increased, and there is a problem that miniaturization is hindered.

For these reasons, there is a method in which the surface mounting is replaced by an ultrasonic thermocompression bonding or thermocompression bonding, and is fixed by a conductive adhesive 8 which has a small pressing force and simplifies equipment. However, in this case, due to the spread of the conductive adhesive 8, the I
Short circuit between the electrode terminals of C2 and the circuit terminals on the bottom wall. For this reason, as shown in FIG. 8, the amount of the conductive adhesive 8 is reduced to prevent an electric short circuit, but there is a problem that the fixing strength is weakened this time. And it was difficult to control these.

(Object of the Invention) An object of the present invention is to provide a surface mounting structure of an IC, a ceramic container, and a crystal oscillator using a conductive adhesive 8 which prevents electric short-circuit and increases connection strength.

[0008]

According to the present invention, a plurality of holes 11 corresponding to the bumps 5 of the IC 2 are provided in the ceramic base 1, the conductive adhesive 8 is buried, and the bumps 5 are inserted into the holes 11. The fixation is the basic solution.

[0009]

According to the present invention, since the conductive adhesive 8 is buried in the plurality of holes of the ceramic base 1 and the bumps 5 are inserted, the spread of the conductive adhesive 8 is prevented. Further, since the conductive adhesive 8 covers the outer surface of the bump 5, the fixing strength is increased. Further, the position and amount of the conductive adhesive 8 can be controlled. Hereinafter, an embodiment of the present invention will be described.

[0010]

FIGS. 1 and 2 are views for explaining a first embodiment of the present invention. FIG. 1 is a sectional view of a crystal oscillator, and FIG. 2 is a partially enlarged sectional view indicated by an arrow P. It is. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. In this example, in this example, the IC 2 is fixed to the bottom surface of the concave portion of the ceramic base 1 by surface mounting, and both ends of the crystal piece 3 from which the extraction electrode 7 (ab) extends are held on the steps. And ceramic base 1
A hole 11 is formed on the bottom surface of the substrate corresponding to the terminal electrode 4 of the IC 2. For example, the bottom wall is composed of upper and lower two layers 1a (1, 2),
a2 is formed by providing a through hole. Then, the circuit terminal 10 connected to the terminal electrode 4 of the IC 2 is exposed.

In such a case, the ceramic base 1
For example, a thermosetting conductive adhesive 8 is formed in the hole 11 provided in
Buried. Then, the bumps 5 of the IC 2 are inserted, and the conductive adhesive 8 is cured.

With such a configuration, the terminal electrodes 4 of the IC 2 and the circuit terminals 10 of the ceramic base 1 are electrically connected by the conductive adhesive 8. Then, the conductive adhesive 8 is filled in the hole 11 to suppress the spread of the surface,
An electrical short circuit between the terminal electrodes 4 and between the circuit terminals 10 can be prevented, and the outer surface of the bump 5 can be covered. Therefore, the position and amount of the conductive adhesive 8 can be controlled, and the fixing strength can be increased. And since it can be fixed with simple equipment, it is economically advantageous.

[0013]

FIG. 3 is a sectional view of a crystal oscillator for explaining a second embodiment of the present invention. The description of the same parts as in the first embodiment is omitted or simplified. The second embodiment is an example in which a concave portion is provided on both sides to accommodate a crystal blank 3 in a concave portion on one surface and an IC 2 in a concave portion on the other surface. That is,
On the bottom surface of the concave portion on the other surface side of the ceramic base 1, I
A hole 11 is formed corresponding to the terminal electrode 4 of C2. For example, the bottom wall is composed of two upper and lower layers 1a (1, 2), a through hole is provided in the lower bottom wall 1a2, and the circuit terminal 10 connected to the terminal electrode 4 of the IC 2 is exposed.

With such a configuration, the hole 1 is formed as described above.
A conductive adhesive 8 is buried in 1 and the bumps 5 of the IC 2 are inserted and fixed. Therefore, the electrical connection between the terminal electrode 4 of the IC and the circuit terminal 10 of the ceramic base 1 is ensured, the electrical short circuit between the terminal electrodes 4 and the circuit terminals 10 is prevented, and the position of the conductive adhesive 8 is determined. The amount can be controlled to increase the fixing strength. And it is economically advantageous.

In particular, in this example, since no pressing force is particularly required, the fixing work is facilitated without bending the bottom wall 1a, and breakage or the like is also prevented. Since the IC 2 can be accommodated after the crystal blank 3 is sealed, the expensive IC 2 is not wasted.

[0016]

[Others] In the first embodiment, both ends of the crystal blank 3 are held on the steps of the ceramic base 1. However, for example, it may be fixed to the upper surface of the frame wall of the ceramic base and covered with the concave cover 9. Good (Fig. 4). Further, the crystal base 3 may be held by holding the ceramic base 1 in a flat plate shape and covered with a concave cover (not shown). The crystal blank 3 is connected to the extraction electrode 7.
Although both ends of the extended one end of (ab) are held, the extraction electrode 7 (ab) may be extended to both ends to hold both ends.

[0017]

According to the present invention, a plurality of holes corresponding to the bumps of an IC are provided in a ceramic base, a conductive adhesive is buried, and the bumps are inserted and fixed in the holes. IC using conductive adhesive with enhanced connection strength
, A ceramic container and a crystal oscillator can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crystal oscillator illustrating a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of a portion indicated by an arrow P of the crystal oscillator for explaining the first embodiment of the present invention.

FIG. 3 is a sectional view of a crystal oscillator illustrating a second embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a crystal oscillator illustrating another example of the present invention.

FIG. 5 is a cross-sectional view of a crystal oscillator illustrating a conventional example.

FIG. 6 is a cross-sectional view of a crystal oscillator illustrating a conventional example.

FIG. 7 is a view of a crystal piece for explaining a conventional example.

FIG. 8 is a partially enlarged cross-sectional view of a crystal oscillator illustrating a conventional example.

[Explanation of symbols]

1 ceramic base, 2 IC, 3 crystal pieces, 4 terminal electrodes, 5 bumps, 6 excitation electrodes, 7 extraction electrodes, 8
Conductive adhesive, 9 cover, 10 circuit terminals, 11
Hole, 12 resin.

Claims (4)

[Claims] In an IC surface mounting structure for fixing an IC having a plurality of bumps to a ceramic base, a hole corresponding to the bump is provided in the ceramic base, a conductive adhesive is buried, and the bump is placed in the hole. A surface mounting structure for an IC, wherein the surface mounting structure is inserted into and fixed to the IC. 2. A ceramic container in which an IC having a plurality of bumps is surface-mounted on a surface of a base, wherein holes corresponding to the bumps are provided on the surface of the base. 3. A crystal oscillator comprising a ceramic container having a concave portion, an IC having a plurality of pumps surface-mounted on a bottom surface of the concave portion, and a crystal piece held on a side wall of the concave portion, the crystal oscillator corresponding to the bump. A crystal oscillator, wherein a hole is provided on the bottom surface of the concave portion, a conductive adhesive is buried, and the bump is inserted and fixed in the hole. 4. A crystal oscillator in which a concave portion is provided on the back surface of a ceramic container in which a crystal piece is hermetically sealed and an IC having a plurality of pumps is surface-mounted, holes corresponding to the bumps are provided on the bottom surface of the concave portion. A crystal oscillator, wherein a conductive adhesive is buried, and the bump is inserted into the hole and fixed.