JPH09307396A - Structure and method for sealing electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity be suppressing the deviation of a cap at the time of hardening a sealing adhesive. SOLUTION: An electronic part element 5 is mounted on a substrate forming electrode patterns 2 and 3, and the cap 11 covering this electronic part element 5 is adhere-sealed onto the substrate 11. A pressure sensitive adhesive 12 is applied onto the cap adhesion part on the substrate 1, and an adhesive for sealing 13 is applied to the opening part of the cap 11. The opening part of the cap 11 is pressed to the cap adhesion part of the substrate 1 to temporality fix the cap 11 onto the substrate 1 by the pressure sensitive adhesive 12. After then the adhesive for sealing 13 is hardened to adhere-seal the substrate and the cap 11.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a sealing structure and a sealing method for an electronic component, and more particularly to a sealing structure and a sealing method suitable for a surface-mounted electronic component.

[0002]

2. Description of the Related Art Conventionally, as a surface mount type electronic component such as a piezoelectric oscillator or a piezoelectric filter, a substrate having an electrode pattern formed on an upper surface thereof, a concave cap, and an internal space formed by the substrate and the cap are provided. There is known one provided with a piezoelectric element to be arranged. The electrodes of the piezoelectric element are connected and fixed to an electrode pattern on the substrate by a conductive adhesive. The cap is placed on the substrate so as to cover the piezoelectric element, and is adhered to the substrate by a sealing adhesive applied to the opening of the cap. The electrode pattern of the substrate is extended outward from the cap bonding portion. By using the extended electrode portion as an external electrode, a surface-mounted electronic component can be obtained.

[0003]

In the case of this type of surface-mounting type electronic component, since a cleaning process is performed at the time of mounting on a printed circuit board, sealing performance is required. The sealing property is secured by an adhesive that bonds the substrate and the cap, and a thermosetting resin such as an epoxy resin is generally used as the sealing adhesive.

When the sealing adhesive is cured by heat treatment, the air existing in the hollow portion of the cap thermally expands to increase the internal pressure, and the adhesive in the middle of curing is broken to try to escape to the outside. A so-called respiratory phenomenon occurs. Due to the air flow generated by such a breathing phenomenon, the cap may move with respect to the substrate, or the viscosity may temporarily decrease during the curing of the adhesive, so that the cap may be displaced by a slight vibration. Therefore, in the conventional sealing method, it is necessary to continue to press the cap by some means during the heat treatment of the adhesive, which requires work for pressing, equipment, jigs, etc. It has caused a decline in sex.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sealing structure and a sealing method for electronic parts, which can suppress the displacement of the cap when the sealing adhesive is cured and can improve the productivity. It is in.

[0006]

In order to achieve the above object, a first aspect of the present invention mounts an electronic component element on a substrate having an electrode pattern formed thereon, and a cap for covering the electronic component element is adhesively sealed on the substrate. In the electronic component that is stopped, the adhesive that bonds the cap and the substrate includes a sealing adhesive and a pressure-sensitive adhesive.

A second aspect of the present invention is a method of sealing an electronic component in which an electronic component element is mounted on a substrate on which an electrode pattern is formed, and a cap for covering the electronic component element is adhesively sealed on the substrate. Step of applying pressure-sensitive adhesive on the cap adhesive part of the device, step of applying sealing adhesive to the opening part of the cap, and placing the opening part of the cap on the cap adhesive part of the substrate to perform pressure-sensitive adhesion. The method includes a step of temporarily fixing the cap on the substrate with an agent, and a step of heating the electronic component to the curing temperature of the sealing adhesive.

When the cap and the substrate are bonded together, the cap and the substrate are temporarily fixed by the pressure sensitive adhesive. In this state, if the electronic component is heated to the curing temperature of the sealing adhesive, the sealing adhesive is cured and the gap between the cap and the substrate can be sealed and both can be bonded. At this time, the displacement of the cap can be surely prevented by the pressure-sensitive adhesive even if the cap is not continuously pressed.

When the pressure sensitive adhesive is partially applied to the cap adhesive portion of the substrate and the sealing adhesive is applied to the entire circumference of the opening of the cap, a step is formed due to the thickness of the pressure sensitive adhesive. Then, when the cap is mounted thereon, the sealing adhesive applied to the cap is pushed away, and the cap is reliably temporarily fixed by the pressure-sensitive adhesive. The viscosity of the sealing adhesive decreases once it is heated, and is extruded to the outside of the cap as the internal pressure of the cap increases, so that a fillet can be formed outside the cap so as to wrap the pressure sensitive adhesive. for that reason,
Assured sealing properties can be obtained.

As the sealing adhesive, a known thermosetting resin adhesive such as epoxy resin is used. Further, the pressure-sensitive adhesive is an adhesive having a function of instantly adhering objects with each other with a slight pressure, that is, a so-called adhesive. As the adhesive, for example, a silicone adhesive, an acrylic emulsion type, an acrylic solution type, a rubber adhesive, or the like is used.

[0011]

FIG. 1 shows a piezoelectric oscillator A which is an example of an electronic component according to the present invention. The substrate 1 is a rectangular thin plate formed by sheet-forming alumina ceramics, and its thickness is, for example, 0.3 to 0.7 mm. Of course, the substrate material is not limited, and any material such as dielectric ceramics or glass epoxy may be used. Electrodes 2 and 3 are formed on the upper surface of the substrate 1. These electrodes 2 and 3 are formed by a known method such as sputtering, vapor deposition, printing, and thermal spraying. Here, Ag / Ag /
A baking type conductive paste of Pd was printed and baked to a thickness of 50 μm or less. Both ends of the electrodes 2 and 3 are drawn out to a concave through hole 1a formed at the side edge of the long side of the substrate 1, and are connected to the electrodes on the lower surface side of the substrate 1 through the electrodes formed on the inner surface of the through hole 1a. It is connected.

The oscillator element 5 is adhesively fixed on the substrate 1 by a material 10 having electrical conductivity and adhesiveness such as a conductive adhesive. As the connection material 10, for example, a solder or a metal terminal may be used as long as the material has an equivalent function. Oscillator element 5 of this embodiment
Is an oscillator in a thickness-shear vibration mode, in which a first electrode 7 is formed over a region approximately one-third from one end of the front surface of the piezoelectric ceramic substrate 6 and approximately two-thirds from the other end of the back surface. The second electrode 8 is formed over the region. Electrodes 7, 8
Are opposed to each other at an intermediate portion thereof with the piezoelectric substrate 6 therebetween, and constitute a vibrating portion. The other ends of the electrodes 7 and 8 extend to both ends of the piezoelectric substrate 6 and are connected to the auxiliary electrodes 7a and 8a formed on the facing surface via the end face electrodes 7b and 8b. The end electrodes 7b and 8b are covered with a protective layer 9.

The electrodes 2, 3 of the substrate 1 and the electrodes 7, 8 of the element 5 are electrically connected by fixing both ends of the oscillator element 5 to the substrate 1 with the conductive material 10.
It is necessary to provide a slight vibration space between the central portion of the element 5 and the substrate 1 at the time of bonding.

A cap 11 to be described later is provided on the upper surface of the substrate 1.
The insulating layer 4 is formed in a frame shape in order to secure insulation between the electrodes 2 and 3 and to flatten a step formed by the electrodes 2 and 3. In this embodiment, glass paste is used as the insulating layer 4 and baked, but the material of the insulating material is not limited at all. When an insulating material is used for the cap 11, the insulating layer 4 is not always necessary.

The opening of the cap 11 is adhered onto the insulating layer 4 of the substrate 1 so as to cover the element 5. As the material of the cap 11, ceramics such as alumina,
There are resins and metals, but in this example, a metal material press-molded into a U-shaped cross section was used in order to secure the miniaturization and dimensional accuracy of the product. The selection of the metal material is arbitrary as long as the product strength and adhesiveness can be obtained. For example, an aluminum alloy, nickel silver, a 42Ni alloy or the like can be used.

A pressure-sensitive adhesive (so-called pressure-sensitive adhesive) 12 is applied to a part of the cap adhesive portion of the substrate 1, particularly on the insulating layer 4, by a method such as printing, pin transfer or dispensing. . As the adhesive 12, there are various types such as silicone type, acrylic type and rubber type. Adhesive force required here (after the adhesive has adhered to the adherend,
The force of peeling from the adherend) differs depending on the shape of the cap 11, the internal volume, the temperature profile during curing, the adhesive application area, and the like. The adhesive 12 used this time is 180
° Adhesive strength by peeling method is about 750gf / 19mm
belongs to. The application area and application site are not particularly limited, but it is preferable that the application is performed partially so as to form a gap through which air can flow when the cap 11 is mounted.
This time, the pattern as shown in FIG. 2 was formed by screen printing. After the adhesive 12 is applied, it is cured (here, 100
℃ × 5 minutes) was performed. If a plurality of adhesives 12 are applied at the same time in the mother substrate state, the number of man-hours for applying the adhesives 12 may be slightly increased.

A sealing adhesive 13 is applied to the entire circumference of the opening of the cap 11, adheres onto the insulating layer 4 of the substrate 1 and is cured. The sealing adhesive 13 is a thermosetting adhesive, and an epoxy adhesive is used here. When the cap 11 is mounted on the substrate 1, a slight pressure (for example, 300 gf / 1 piece × 0.2 se) is applied to ensure the adhesiveness with the adhesive 12.
c) was performed.

Thereafter, the piezoelectric oscillator A is put into a curing furnace and heat-treated in a predetermined temperature profile. Due to the breathing action caused by heating, the air inside the cap 11 may escape, and the cap 11 may move by a small amount due to the reaction. However, in the present invention, the cap 11 includes the adhesive 12
Since it is temporarily fixed by, the displacement of the cap 11 due to the breathing action is prevented. As a result, it is not necessary to pressurize the cap 11 during the curing process, and the work for pressing, equipment, jigs, etc. are not required, and the productivity is significantly improved.

FIG. 3 shows an example of the sealing method according to the present invention. FIG. 3A shows a state before the cap 11 is mounted,
An insulating layer 4 is formed on the cap bonding portion of the substrate 1, and an adhesive 12 is applied on the insulating layer 4. Also,
A sealing adhesive 13 is applied to the opening of the cap 11. FIG. 3B shows a state in which the cap 11 is mounted on the substrate 1, and the sealing adhesive 13 applied to the opening of the cap 11 is pushed away to both sides by the pressure-sensitive adhesive 12 that rises in a step shape. Adhesive 1 is the opening
Touch 2. Therefore, the cap 11 is temporarily fixed by the adhesive 12. FIG. 3C shows a state in which the electronic component A has been subjected to a heat treatment. At the time of heating, the viscosity of the sealing adhesive 13 is once reduced, and the adhesive 13 is increased as the internal pressure of the cap 11 increases.
Is pushed out of the cap 11. Then, a uniform fillet 13a is formed outside the cap 11 so as to wrap the adhesive 12. Therefore, a reliable sealing property can be obtained. Since the viscosity of the sealing adhesive 13 is reduced during the heat treatment, the cap 11 is likely to be laterally displaced from the substrate 1 due to a breathing phenomenon or vibration, but the adhesive 12 temporarily fixes the cap 11. Therefore, the lateral displacement can be prevented in advance without continuously pressing the cap 11.

In the above embodiment, since heat treatment is performed after the substrate 1 and the cap 11 are adhered to each other, the fillet 13a of the adhesive 13 may be formed outside the cap 11 largely. In order to downsize the electronic component, it is desired to reduce the size of the fillet 13a outside the cap 11. As a countermeasure, the substrate 1 and the cap 11
It is conceivable to preheat the adhesive to near the curing temperature of the adhesive 13 (for example, 150 ° C.). In this case, even if the preheated cap 11 is mounted, the viscosity of the adhesive 13 is lowered, so that the cap 11 is easily displaced laterally with respect to the substrate 1. However, in the present invention, since the cap 11 is temporarily fixed by the adhesive 12, even if the viscosity of the adhesive 13 decreases, the lateral displacement of the cap 11 can be prevented. In this state,
The adhesive 13 may be cured.

In the case of the above preheating method, the air inside the cap 11 is already heated at the time of mounting on the substrate 1, so that when the adhesive 13 is cured, the air inside the cap 11 expands and the adhesive 13 is removed. Cap 11 without pushing
The outer fillet 13a can be made smaller. for that reason,
The outer dimensions of the substrate 1 can be reduced, and the electronic component can be downsized.

The present invention is not limited to the piezoelectric oscillator having the built-in oscillator element as in the above embodiment, but a capacitance built-in oscillator having an oscillator element and a capacitor element as well as a capacitance portion formed on a substrate. It can also be applied to a resonator with a built-in capacitor. Further, the present invention can be applied to other electronic components such as a filter and a circuit module.

[0023]

As is apparent from the above description, according to the present invention, the sealing adhesive and the pressure-sensitive adhesive are used as the adhesive for bonding the substrate and the cap. It can be temporarily fixed with an adhesive, and it is possible to prevent lateral displacement of the cap during heat curing without applying pressure. Therefore, the work, equipment, and jig required for pressurization are not required, the productivity is significantly improved, and the defect rate due to the lateral displacement of the cap can be reduced. Further, since the cap is temporarily fixed at the same time as mounting the cap, it is possible to assemble with the mechanical accuracy as it is. Further, handling before the adhesive is cured can be eliminated, and deviation due to vibration during transportation can be prevented, so that the defective rate is further reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an example of an electronic component according to the present invention.

FIG. 2 is a plan view of the substrate of FIG. 1;

FIG. 3 is a view showing a step of sealing an electronic component according to the present invention.
FIG. 6 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 1 Substrate 2,3 Electrode 4 Insulating Layer 5 Oscillator Element 7,8 Electrode 11 Cap 12 Pressure Sensitive Adhesive (Adhesive) 13 Sealing Adhesive

Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical location H03H 9/17 H03H 9/17 A (72) Inventor Takashi Toda 2 26-10 Tenjin, Nagaokakyo, Kyoto Stock Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. An electronic component in which an electronic component element is mounted on a substrate on which an electrode pattern is formed, and a cap covering the electronic component element is adhesively sealed on the substrate, wherein the cap is adhered to the substrate. The agent includes a sealing adhesive and a pressure-sensitive adhesive, and a sealing structure for electronic parts. 2. A method for sealing an electronic component, comprising mounting an electronic component element on a substrate having an electrode pattern formed thereon, and adhesively sealing a cap covering the electronic component element on the substrate, comprising a cap bonding portion of the substrate. Applying pressure-sensitive adhesive on top, applying sealing adhesive to the opening of the cap, placing the opening of the cap on the cap-adhesive part of the substrate, and using the pressure-sensitive adhesive to attach the cap. A step of temporarily fixing it on the substrate, a step of heating the electronic component to the curing temperature of the sealing adhesive,
An electronic component sealing method including: