JP3261311B2 - Electronic component sealing method - Google Patents

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, a surface mount type electronic component includes a substrate having an electrode pattern formed on an upper surface, a concave cap, and a piezoelectric element disposed in an internal space formed by the substrate and the cap. Are known. 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-mounted electronic component, a cleaning process is performed when the electronic component is mounted on a printed circuit board, so that a sealing property is required. The sealing property is ensured by an adhesive for bonding the substrate and the cap, and a thermosetting resin such as an epoxy resin is generally used as the adhesive.

FIG. 1 shows an example of a temperature profile when the adhesive is cured by heating. Linearly increasing the temperature from the start of heating, the maximum temperature (in this example at time t ₁ 15
0 ° C.) and hold at this temperature until the adhesive is completely cured. In the course of such heat treatment, the adhesive sequentially changes from liquid to gelled to solid.

In general, when the sealing adhesive is cured by heat treatment, the air present in the hollow portion of the cap thermally expands to increase the internal pressure, so that the adhesive in the middle of the curing is broken and tends to escape to the outside. A so-called respiratory phenomenon occurs. Such a breathing phenomenon starts almost at the same time as the rise in the internal temperature of the cap, and continues until the time when the temperature rise ends (the furnace temperature stabilizes).

On the other hand, when many adhesives are cured by a heat treatment, gelation starts during the temperature rise. That is, gelation of the adhesive starts in the middle of the aforementioned respiration phenomenon. However, if the adhesive begins to gel during the breathing phenomenon, a vent hole is formed in the adhesive due to the breathing phenomenon, and this vent hole cannot be closed, leaving a vent hole in the finished product. In addition, there is a problem that sealing properties cannot be obtained.

As a countermeasure, there is a method in which the cap is strongly pressurized so as not to cause a breathing phenomenon when the adhesive is cured. In such a case, a large-scale pressurizing device is required and natural phenomena are suppressed, so that the reliability is low.

It is an object of the present invention to provide a method for sealing an electronic component, which can easily and reliably obtain a sealing property.

[0009]

In order to achieve the above object, according to the first aspect of the present invention , an electronic component element is disposed inside a first exterior member and a second exterior member, and both exterior members are connected to each other. What is claimed is: 1. A method for sealing an electronic component in which the inside is sealed by bonding using a thermosetting adhesive, wherein the electronic component is bonded to a first exterior member and a second exterior member with a liquid adhesive. A second step of raising the internal temperature of the assembled electronic component to the adhesive curing temperature, and maintaining the internal temperature of the electronic component at the adhesive curing temperature until the adhesive is cured. A third step, wherein the adhesive maintains a liquid state without gelling in the second step;
A method of sequentially changing from a liquid state to a gel state to a solid state in a step, and a property of increasing a viscosity at a stage of changing from a liquid state to a gel state.

[0010] The adhesive of the present invention is obtained after the temperature rise process during curing.
Since gelation starts (after the end of breathing) , the adhesive is still in a liquid state having fluidity at the time when minute ventilation holes are generated by the breathing phenomenon. Therefore, the surrounding adhesive can flow and fill the ventilation holes. When the temperature rise process ends and the process becomes a constant temperature process at the curing temperature, the respiration phenomenon ends,
Thereafter, the gelation of the adhesive starts. Therefore, in the state of the finished product, no ventilation hole remains, and good sealing properties can be easily and reliably obtained. In this case, since pressurization for obtaining the sealing property is not required, a large-scale pressurizing device is not required, and an unnecessary load is not applied to the electronic component, and the electronic component is damaged by the pressurization. Can be eliminated. In the present invention, the gel time is the time from the start of heating up to the start of gelling of the adhesive, and the breathing time is the end of the breathing phenomenon from the start of heating (overheating).
Time until the end of the process) . As the adhesive, it is preferable to use a thermosetting resin to which a plasticizer or a curing retarder is added. This allows
A desired effect can be obtained only by adding an additive to the adhesive without changing the temperature profile at the time of raising the temperature.

A substrate having an electronic component element mounted thereon may be used as the first exterior member, and a cap covering the electronic component element and having an opening bonded to the substrate may be used as the second exterior member. A plurality of electrodes connected to the conductive parts of the electronic component element are formed on the substrate. In this case, a sealed type surface mount electronic component can be obtained.

In the case where a substrate and a cap are used as an exterior member, a piezoelectric element having first and second electrodes is used as the electronic component element, and two electrodes are formed on the substrate. The first and second electrodes of the piezoelectric element may be connected to the two electrodes, respectively. In this case, a sealed surface mount type piezoelectric component can be obtained.

Further, when a substrate and a cap are used as the exterior member, a piezoelectric element and a capacitor element bonded to each other may be used as electronic component elements. In this case, the first and second electrodes are formed on the piezoelectric element, two individual electrodes connected to the first and second electrodes of the piezoelectric element are formed on one main surface of the capacitor element, and the other main surface is formed. Then, a counter electrode facing the individual electrode is formed. Then, first to third electrodes are formed on the substrate, and the first and second electrodes of the substrate are formed.
By connecting two individual electrodes of the capacitor element to the electrodes of the above and connecting the counter electrode of the capacitor element to the third electrode of the substrate, a piezoelectric oscillator with a built-in capacitor used in a Colpitts type oscillation circuit can be obtained. Can be.

[0014]

FIG. 2 shows a piezoelectric oscillator A as a first embodiment of an electronic component according to the present invention. The substrate 1 is a rectangular thin plate made of alumina ceramics or the like, and electrodes 2 and 3 are formed on the upper and lower surfaces thereof by printing and firing a baking type conductive paste containing Ag as a main component. The electrodes 2 and 3 on the upper and lower surfaces of the substrate 1 are connected via the inner surface of a through hole 1a formed on the outer peripheral edge of the substrate 1, and are formed in a headband shape. On the upper surface of the substrate 1, an insulating layer 4 made of a glass base or the like is formed in a frame shape in order to ensure insulation between a cap 11 described later and the electrodes 2 and 3 and to flatten a step formed by the electrodes 2 and 3. ing.

An oscillator element 5 is bonded and fixed on the substrate 1 by a material 10 having both functions of conductivity and adhesion, such as a conductive adhesive. The oscillator element 5 of this embodiment is an oscillator element of a thickness shear vibration mode,
A first electrode 7 is formed over a region of about 2/3 from one end of the front surface of the piezoelectric ceramic substrate 6, and a second electrode 8 is formed over a region of about 2/3 from the other end of the back surface. ing.
One ends of the electrodes 7 and 8 are opposed to each other at an intermediate portion 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 auxiliary electrodes 7a and 8a formed on the opposing surfaces via end electrodes 7b and 8b. The end electrodes 7b and 8b are covered with a protective layer 9.

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

The opening of the cap 11 is placed on the insulating layer 4 of the substrate 1 so as to cover the oscillator element 5.
Glued by Examples of the material of the cap 11 include ceramics such as alumina, a resin, and a metal. In this embodiment, a metal material press-formed into a U-shaped cross section was used in order to reduce the size of the product and ensure dimensional accuracy. 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. The adhesive 12 is an epoxy-based adhesive, which is applied to the bottom surface of the opening of the cap 11 by transfer or the like, and then is applied to the insulating layer 4.
Glued on top and cured.

When the cap 11 is bonded and sealed to the substrate 1, the piezoelectric oscillator A is put into a curing furnace and is subjected to a heat treatment with a temperature profile as shown in FIG. The air inside the cap 11 escapes due to the respiration by heating,
At this time, the cap 11 may move by a very small amount due to the reaction. Therefore, in order to prevent the cap 11 from shifting, the cap 11 may be lightly pressed from above (for example, about 0 to several tens g).

In order to prevent minute ventilation holes from remaining in the adhesive 12 due to the respiration phenomenon, the adhesive 12 having a gel time longer than the respiration time due to a rise in temperature during curing is used. That is, when the heat treatment is performed according to the temperature profile shown in FIG. 3, the respiratory phenomenon starts almost at the same time as the temperature rise,
The process ends when the temperature inside the cap 11 reaches the temperature inside the furnace. In the case of FIG. 3, the time is about 5 minutes.

In the case of this example, the gel time is adjusted to be longer than the breathing time (5 minutes) so that the gelation starts after the end of the breathing, thereby preventing the ventilation holes from remaining. Methods for adjusting the gel time include changing the type of curing agent contained in the adhesive 12, adding a plasticizer, and adding a curing retarder. Here, a plasticizer was added. By such adjustment, in this embodiment, the gel time is set to about 10 minutes, which is twice the respiration time.

Next, the following table shows comparison data of the residual ratio of the ventilation holes between the piezoelectric oscillator A of the present invention using the adhesive 12 having a long gel time as described above and two types of conventional piezoelectric oscillators. Show. Specifically, comparison was made by a leak test method (gross leak test) by immersion in a florinate solution (trade name: manufactured by 3M). All conventional products use an adhesive that has a shorter gel time than the breathing time,
The case where no pressurization is applied is the case where respiration is confined by strong pressurization. The number of evaluations is 50,000 each.

[0022]

[Table 1]

As is apparent from the above comparative data, it can be seen that in the present invention, the residual ratio of the ventilation holes of the adhesive 12 is almost zero. That is, in the case of the conventional product, since the adhesive cannot fill back the minute ventilation holes generated by the respiration phenomenon at the time of curing of the adhesive, the ventilation holes at the time of the start of gelation remain as they are. On the other hand, in the product of the present invention, the adhesive 12 in an ungelled state flows and fills the air holes, so that no air holes remain. In addition, since the fluidity of the adhesive 12 in an ungelled state is used, the sealing method is not against natural phenomena, and has higher stability and reliability than the pressure method. Further, since no excessive load is applied, the substrate 1 and the cap 11 are not damaged.

FIG. 4 shows a second embodiment of the electronic component according to the present invention. The electronic component B includes one oscillator R and two capacitors C ₁ and C used in a Colpitts type oscillation circuit.
₂ and the electric circuit thereof is as shown in FIG.

The substrate 20 is a rectangular thin plate made of alumina ceramics or the like, and the substrate 20 is formed with three strip-shaped electrodes 22, 23, and 24 in a headband shape in parallel with the short side. The electrode 22 is an input electrode, the electrode 23 is a ground electrode, and the electrode 24 is an output electrode. The electrodes 21 to
23 are drawn out to a concave through-hole 20a formed on the long side of the substrate 20, and the through-hole 2
It is connected to an electrode on the lower surface side of the substrate 20 via an electrode formed on the inner surface of Oa.

On a portion of the substrate 20 corresponding to the cap bonding portion, a frame-shaped insulating layer 25 is formed with a constant thickness. On the substrate 20, a material 30-32 having both conductivity and adhesive functions such as a conductive adhesive is used.
An oscillator element 40 and a capacitor element 50 which are laminated and integrated are bonded and fixed.

The oscillator element 40 of this embodiment is an oscillator element of a thickness shear vibration mode. That is, as shown in FIG. 6, the electrode 42 is formed over a region approximately one-third from one end of the front surface of the piezoelectric substrate 41, and approximately two-thirds from the other end of the back surface.
The electrode 43 is formed over the region of No. 3. Electrode 4
One end portions of the piezoelectric substrates 2 and 43 are opposed to each other at an intermediate portion of the piezoelectric substrate 41 with the piezoelectric substrate 41 therebetween, and constitute a vibrating portion. The electrodes 42, 4
The other end portions 42 a and 43 a of 3 pass through both end surfaces of the piezoelectric substrate 41 to the other surface side.

As shown in FIG. 7, two capacitor elements 50 are provided on the surface of a dielectric substrate (for example, a ceramic substrate) 51 having the same length and the same width as the oscillator element 40. The individual electrodes 52 and 53 are formed, and one counter electrode 54 facing the individual electrodes 52 and 53 is formed on the back surface, and two opposing portions of the individual electrodes 52 and 53 and the counter electrode 54 are formed. The number of capacitance portions C ₁ and C ₂ are formed. The ends 52a, 53 of the individual electrodes 52, 53
“a” extends to the back side through the end face of the substrate 51.

The back surface of the oscillator element 40 and the capacitor element 5
The surface 0 is bonded and fixed at both ends by materials 33 and 34 having both conductivity and adhesive functions, such as a conductive adhesive. At this time, a predetermined vibration space is formed between the vibrating portion of the oscillator element 40 and the capacitor element 50 by the thicknesses of the materials 33 and 34. In this manner, one electrode 43 of the oscillator element 40 and one individual electrode 52 of the capacitor element 50 are connected, and the other electrode 4
2 and the other individual electrode 53 are connected. Note that damping materials 35 and 36 for frequency adjustment made of resin or the like are applied on both ends of the surface of the oscillator element 40.

After the oscillator element 40 and the capacitor element 50 are bonded and integrated, the back side of the capacitor element 50 is bonded to the substrate 20 by using materials 30 to 32, and the end 52a of one of the individual electrodes 52 of the capacitor element 50 is formed. Is the input electrode 22, and the end 53 a of the other individual electrode 53 is the output electrode 2.
4, the counter electrode 54 is connected to the ground electrode 23, respectively.

The opening of the cap 60 is adhered to the substrate 20 with an adhesive 61 so as to cover the oscillator element 40 and the capacitor element 50. The cap 60 is formed of the same material and the same shape as the cap 11 in the first embodiment, and the detailed description is omitted here. An epoxy-based adhesive was used as the adhesive 61, applied to the bottom of the opening of the cap 60, and then adhered onto the insulating film 25 and cured. As the adhesive 61 in this case, similarly to the adhesive 12 in the first embodiment, an adhesive having a gel time longer than a respiration time due to a rise in temperature during curing is used. As a result, the same good sealing performance as in the first example was obtained.

In the above embodiment, an example in which a metal cap is used as the cap has been described, but a non-metal cap such as alumina may be used. In this case, since the cap itself is non-conductive, there is no need to form an insulating film on the substrate, and the cap may be directly bonded to the substrate. The thickness of the electrode is easily affected by the absence of the insulating film. However, if the amount of the adhesive is slightly increased, the gap between the cap and the substrate can be filled, and a good sealing effect can be obtained.

The present invention relates to a piezoelectric component having a built-in oscillator element as in the above embodiment, a built-in capacity type oscillator having an oscillator element and a capacitor element, and a built-in capacity type having a capacity portion formed on a substrate. Also applicable to oscillators. Further, the present invention can be applied to other electronic components such as a filter and a circuit module. In addition, the present invention is not limited to the configuration including the substrate on which the electronic component element is mounted and the cap as in the embodiment, and a concave portion is formed in the first exterior member, and the electronic component element is stored in the concave portion. The recess may be bonded and sealed with a second exterior member. Furthermore, the present invention is not limited to surface-mounted electronic components, but can be applied to electronic components with terminals.

[0034]

As is apparent from the above description, according to the present invention, since the non-gelled adhesive backfills the minute ventilation holes generated by the respiration phenomenon at the time of curing the adhesive, it is ensured. Sealability is obtained. In addition, since this sealing method does not go against natural phenomena using the fluidity of the ungelled adhesive, it has higher stability and reliability than other methods such as pressure sealing. Further, since a strong pressing force is not required at the time of hardening, mass production can be performed with a small device, and electronic components are less damaged. Furthermore, if the gel time is adjusted according to the profile at the time of curing, the sealing property can be obtained regardless of the temperature profile, and there is an effect that the degree of freedom in the process design is increased.

[Brief description of the drawings]

FIG. 1 is a temperature profile diagram when a conventional adhesive is cured.

FIG. 2 is an exploded perspective view of the first embodiment of the electronic component according to the present invention.

FIG. 3 is a temperature profile diagram when the adhesive of the present invention is cured.

FIG. 4 is an exploded perspective view of a second embodiment of the electronic component according to the present invention.

5 is an electric circuit diagram of the electronic component shown in FIG.

FIG. 6 is a front and rear view of an oscillator element used for the electronic component of FIG. 4;

FIG. 7 is a front and rear view of a capacitor element used for the electronic component of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 substrate 2, 3 electrode 4 insulating layer 5 oscillator element 7, 8 electrode 11 cap 12 sealing adhesive

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Kawakami 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-60-227450 (JP, A) JP-A Sho 64-37871 (JP, A) JP-A-5-218238 (JP, A) JP-A-7-45751 (JP, A)

Claims (5)

(57) [Claims] An electronic component element is disposed inside a first exterior member and a second exterior member, and the interior is sealed by bonding both exterior members using a thermosetting adhesive. A first method of assembling an electronic component by bonding a first exterior member and a second exterior member with a liquid adhesive;
A second step of raising the internal temperature of the assembled electronic component to the adhesive curing temperature, and a third step of maintaining the internal temperature of the electronic component at the adhesive curing temperature until the adhesive is cured. The adhesive maintains a liquid state without gelling in the second step, and sequentially changes from a liquid state to a gel state to a solid state in the third step,
A method for sealing an electronic component, characterized in that the viscosity increases at the stage of changing from a liquid state to a gel state. 2. The method for sealing an electronic component according to claim 1, wherein
There are, the adhesive, the electronic component, characterized in that the thermosetting resin in which a plasticizer or retarder is added
Sealing method. 3. The sealing of an electronic component according to claim 1 or 2.
In the method , the first exterior member is a substrate on which the electronic component element is mounted, the second exterior member is a cap that covers the electronic component element and has an opening adhered to the substrate, and the substrate includes an electronic component. Sealing an electronic component, wherein a plurality of electrodes connected to a conductive portion of the element are formed.
How . 4. The method for sealing an electronic component according to claim 3, wherein said electronic component element is a piezoelectric element having first and second electrodes, and said substrate has two piezoelectric elements. electrodes are formed, the first and second of said piezoelectric element to the two electrodes of the substrate
Sealing method of the electronic component, wherein a electrode are connected. 5. The electronic component sealing method according to claim 3, wherein the electronic component element comprises a piezoelectric element and a capacitor element bonded to each other, and the piezoelectric element includes a first element. And the second
Are formed on one main surface of the capacitor element facing the piezoelectric element, and two individual electrodes connected to the first and second electrodes of the piezoelectric element are formed on the other main surface. 2 facing the electrode
One counter electrode is formed to form one capacitor. First to third electrodes are formed on the substrate. Two capacitor elements are provided for the first and second electrodes of the substrate.
A method for sealing an electronic component, wherein a plurality of individual electrodes are connected to each other, and a counter electrode of a capacitor element is connected to a third electrode of a substrate.