JP3489508B2 - Conductive cap, electronic component, and method of forming insulating film on conductive cap - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive cap for surrounding an electronic element such as a piezoelectric element mounted on the upper surface of a substrate, an electronic component having the conductive cap, and an insulating film formed on the conductive cap. On how to do.

[0002]

2. Description of the Related Art Conventionally, an electronic component element such as a piezoelectric resonator has a package structure using a conductive cap. A package structure of this type will be described with reference to FIG.

This package structure has a rectangular plate-shaped substrate 51 made of an insulating material such as alumina, and a metal cap 52. On the upper surface of the substrate 51, terminal electrodes 53 and 54 for electrically connecting to the outside are formed. The terminal electrodes 53 and 54 are provided on the upper surface 51a of the substrate 51 in order to enable surface mounting on a printed circuit board or the like.
Not only is it formed to reach the side surface, the end surface, and the lower surface.

On the other hand, although not shown in FIG. 6, a piezoelectric element is mounted on the upper surface 51a of the substrate 51 by using a conductive bonding agent such as solder or a conductive adhesive. The electrode of the piezoelectric element is electrically connected to the terminal electrode 53 or the terminal electrode 54.

To seal the piezoelectric element, a metal cap 52 having an opening at the bottom is joined to the substrate 51.
By the way, in order to ensure electrical insulation between the substrate 52 and the terminal electrodes 53, 54, a rectangular frame shape is formed on the substrate 51 at a portion where the lower opening end face of the metal cap 52 contacts the upper face 51a of the substrate 51. Insulating film 55 is formed. The insulating film 55 is formed by printing a synthetic resin or by printing glass and baking it, and has a thickness of about 0.1 mm. Therefore, even when the metal cap 52 is used, the height of the obtained chip-type electronic component can be reduced.

However, in recent years, it has been required to reduce the mounting area of electronic parts. In this case, as miniaturization progresses, the insulating film 55 is printed with high accuracy on the upper surface 51a of the substrate 51, It has become very difficult to form.

On the other hand, Japanese Unexamined Patent Publication No. 6-132762 discloses an electronic component 71 with a cap shown in FIG. Here, the upper surface of the substrate 72 made of an insulating material,
Terminal electrodes 73 and 74 are formed so as to reach the side surface and the lower surface. The piezoelectric element 75 is joined to the terminal electrodes 73 and 74 with solders 76 and 77.

A metal cap 78 is provided on the substrate 72.
Is bonded to the upper surface of the substrate using an insulating adhesive. Here, in order to prevent a short circuit between the terminal electrodes 73, 74 and the metal cap 78, an insulating layer 79 is formed on the entire inner surface of the metal cap 78.

Although this prior art does not describe a specific method for forming the insulating layer 79, the insulating layer is pre-coated in the state of the plate material before the metal cap 78 is molded, and the pre-coated plate material is probably used. It seems that is molded into a cap shape.

[0010]

However, in obtaining the metal cap described in Japanese Patent Laid-Open No. 6-132762, it is necessary to surely position the insulating layer at the contact portion between the terminal electrodes 73 and 74 and the metal cap 78. As shown in FIG. 7, it is necessary to bend the opening peripheral edge of the metal cap 78 outward. Therefore, the metal cap 7
The process for obtaining 8 tends to be complicated. In addition, in such a bending process, the insulating layer 79 may be peeled off, and electrical insulation between the metal cap 78 and the terminal electrodes 73 and 74 may not be ensured.

An object of the present invention is to reliably achieve electrode-like insulation between a conductive cap and a terminal electrode on a substrate,
And a conductive cap that can be obtained by a simple process and can further reduce the size and height of an electronic component using a conductive cap, an electronic component having the conductive cap, and an insulating film formation of the conductive cap. To provide a method.

[0012]

A conductive cap for an electronic component according to the present invention has a downward opening so as to surround an electronic component element mounted on the upper surface of a substrate having at least a terminal electrode formed on the upper surface. A conductive cap for an electronic component, which has an opening and is fixed to the upper surface of the substrate from the opening side with an insulating adhesive , wherein an insulating film is formed on the end surface of the opening and on the inner and outer side surfaces connected to the end surface near the end surface. Is formed.

In a particular aspect of the present invention, the insulation resistance between the open end surface of the conductive cap and the outer surface of the insulating film is at least 10 ⁹ Ω. Further, in another specific aspect of the present invention, the thickness of the insulating film is in the range of 4 to 25 μm.

In another specific aspect of the present invention, when the vicinity of the opening end surface of the conductive cap is viewed in a cross section in a direction orthogonal to the circumferential direction of the conductive cap, the opening end surface and an inner side surface continuous with the opening end surface are formed. Form a single curve, and the radius of curvature R of the curve is in the range of 80 μm to 150 μm.

An electronic component according to the present invention is a substrate having at least an upper surface on which a plurality of terminal electrodes are formed, and an electronic component fixed on the substrate and electrically connected to the plurality of terminal electrodes. An element and an electrically conductive cap having an opening below, an insulating film being formed on the opening end face and in the vicinity thereof, and being joined to the substrate from the opening side by an insulating adhesive. And

In a particular aspect of the electronic component according to the present invention,
Piezoelectric elements are used as electronic components. Further, in still another specific aspect of the electronic component according to the present invention, a metal cap is used as the conductive cap.

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIG. 1A is a sectional view of an electronic component according to an embodiment of the present invention and a partially cutaway sectional view showing an enlarged main part thereof. In the electronic component 1 with a cap, the substrate 2
And a metal cap 3 as a conductive cap constitutes a package, and the piezoelectric element 4 is provided in the package.
Is stored.

The substrate 2 is made of insulating ceramics such as alumina and has a rectangular plate shape. However, the substrate 2 may be made of another insulating material such as synthetic resin.

Terminal electrodes 5 and 6 are formed to extend from the upper surface 2a of the substrate 2 through the end surfaces 2b and 2c to the lower surface 2d. On the upper surface 2a of the substrate 2, the above-mentioned piezoelectric element 4 is fixed using a conductive bonding agent 7, 8 such as solder. The conductive bonding agents 7 and 8 also have a function of electrically connecting an electrode (not shown) of the piezoelectric element 4 and the terminal electrode 5 or the terminal electrode 6.

As the piezoelectric element 4, it is possible to use a piezoelectric resonator or a piezoelectric filter that utilizes an appropriate piezoelectric effect. To seal the piezoelectric element 4, a metal cap 3 is adhered to the upper surface of the substrate 2 using an insulating adhesive (not shown). In addition, the metal cap 3 has an opening 3a at the bottom, and the opening end face 3b, and the inner side face 3c and the outer side face 3d connected to the opening end face 3b, near the end face 3b,
The insulating film 9 is formed.

The metal material forming the metal cap 3 is not particularly limited, and for example, aluminum or stainless steel can be used. As shown in FIGS. 2A to 2C, the metal cap 3 has a substantially rectangular parallelepiped shape. The metal cap 3 can be easily obtained by molding a plate-shaped metal member. Also, by the method described below,
The insulating film 9 is formed on the metal cap 3.

The characteristic of the electronic component 1 of this embodiment is that the insulating film 9 is formed on the metal cap 3.
The structure of the portion where the insulating film 9 is formed is shown in FIG.
This will be described in more detail with reference to (b).

As shown in FIG. 1B, when the vicinity of the opening edge of the metal cap 3 is viewed in a cross section in a direction orthogonal to the circumferential direction of the opening 3a of the metal cap, the metal cap 3 is joined to the terminal electrodes 5 and 6. The open end surface 3b and the inner side surface 3c connected to the open end surface 3c form one curve, and the curvature radius R of the curve is in the range of 80 to 150 μm. Further, the insulating film 9 is formed on the opening end face 3b and the inner side face 3c.
In the vicinity of the opening end face and in the vicinity of the opening end face of the outer side surface 3d.

An appropriate insulating material can be used as the material forming the insulating film 9, but as will be apparent from the manufacturing process described later, an insulating resin that can be melt-coated is preferably used. More preferably, as the insulating resin, one having heat resistance that can withstand heat when mounting the electronic component with a cap on a printed circuit board or the like by the reflow soldering method is used. Furthermore, the insulation resistance of the insulating film 9 is preferably 10 ⁹ Ω or more.

When a suitable insulating synthetic resin such as epoxy resin or polyimide resin is used as the material for the insulating film 9, the insulation resistance is set to 10 ⁹ Ω or more.
The thickness of the insulating film 9 is preferably 4 μm or more. If the thickness of the insulating film is less than 4 μm, the insulation resistance may decrease and the reliability may decrease. Further, the upper limit of the thickness of the insulating film 9 is not particularly limited in order to secure the insulation resistance, but when it exceeds 25 μm, the insulating film portion adhered to the side surfaces 3c and 3d connected to the opening end surface 3b of the metal cap 3 Of the metal cap 3, the inner size of the metal cap 3 becomes smaller and the outer size becomes larger. Therefore, there is a restriction on the size of the piezoelectric element 4 that can prepare or store the large substrate 2.

As described above, the opening end surface 3b of the metal cap 3 and the inner side surface 3c connected to the opening end surface 3b may be constructed so that the radius of curvature R shown in FIG. 1 (b) is in the range of 80 to 150 μm. desirable. When the radius of curvature R is less than 80 μm, the contact area between the metal cap 3 and the terminal electrodes 5 and 6 on the substrate 2 becomes small, and the reliability of bonding the metal cap 3 to the substrate 2 may decrease. In addition, the insulating coating 9 is unlikely to adhere to the metal cap 3, and it is difficult to form the insulating coating 9 having a sufficient film thickness. On the contrary, when the radius of curvature R exceeds 150 μm, metal burrs and edges are likely to be formed on the open end surface 3b of the metal cap 3, and the insulating film 9 is less likely to adhere.

The insulating resin forming the insulating film 9 preferably has a melt viscosity suitable for applying to the metal cap 3, and preferably has a viscosity at 25 ± 5 ° C. 5000 to 20000 cp
Those in the range of s are used. The above viscosity is 5000 cp
If it is less than s, it is difficult to obtain an insulating film having a sufficient film thickness if the number of times of transfer is not increased when applying by a transfer method. The viscosity is preferably 5000 cps or more in order to obtain the insulating film 9 having an appropriate film thickness by transferring twice.
On the contrary, if the viscosity exceeds 20000 cps, the thickness of the insulating film 9 formed by one transfer process becomes too thick, and the same problem as in the case where the thickness of the insulating film 9 exceeds 25 μm tends to occur.

Next, a method for forming the insulating film 9 on the metal cap 3 will be described with reference to FIGS. In this method, a holder 11 is prepared as shown in the bottom view of FIG. A rubber layer 11a having adhesiveness is formed on the lower surface of the holder 11. Adhesive rubber layer 11
a is formed by using an appropriate pressure sensitive adhesive such as silicone or acrylic.

A plurality of metal caps 3 are attached to the adhesive rubber layer 11a. Each metal cap 3 is attached to the rubber layer 11a from the top plate side.

Further, as shown in FIG. 3, the plurality of metal caps 3 are arranged in a matrix. In order to attach the plurality of metal caps 3 to the holder 11 as described above, the plurality of metal caps 3 are placed in a matrix on a stage (not shown) in advance, and the metal caps 3 are placed above the metal caps 3. Then, the rubber layer 11a of the holder 11 may be lowered, and the top plate of the metal cap 3 may be brought into contact with the rubber layer 11a.

Thereafter, as shown in FIG. 4, the metal cap 3 supported by the holder 11 may be lowered onto the insulating film forming stage 12. An insulating resin layer 9A is formed on the upper surface 12a of the insulating film forming stage 12. The insulating resin layer 9A is formed by melting and applying the resin forming the insulating film 9 described above. However, the insulating resin layer 9 is not yet dried and has a viscosity of 5000 to 20000c at 25 ± 5 ° C.
It is adjusted to be in the ps range.

Therefore, the metal cap 3 supported by the holder 11 is brought into contact with the insulating resin layer 9A from the opening 3a side,
Then, by pulling up, the insulating resin is applied to the peripheral edge of the opening 3a of the metal cap 3. Thereafter, the applied insulating resin is dried to form the above-described insulating film 9.

That is, according to the insulating film forming method of this embodiment, the insulating film 9 can be reliably and easily formed on the plurality of metal caps 3 by the transfer method. Preferably, the transfer step is performed multiple times. Ie 1
Even if a pinhole is formed in the insulating film 9 formed by the transfer of a single time, the transfer process is repeated a plurality of times to cause a short circuit between the metal cap 3 and the terminal electrodes 5 and 6 due to the pinhole. It can be surely prevented.

After the insulating film 9 is formed on the metal cap 3 as described above, the metal cap 3 is bonded to the substrate 2 on which the piezoelectric element is mounted via an insulating adhesive. In this case, an insulating adhesive is applied to the peripheral edge of the opening of the metal cap 3, and each metal cap 3 is bonded to the substrate 2. This is because, in the step of joining the metal cap 3 to the substrate 2 using an insulating adhesive, the piezoelectric element 4 needs to be reliably sealed in the package, and therefore the bonding work must be performed with high accuracy. is there.

That is, in the transfer process for forming the insulating film 9, since such high precision is not required, a plurality of metal caps can be processed at one time as described above. In the process of adhering the metal cap 3 to the substrate 2, a large amount of the metal cap 3 is attached to the substrate 2 at a time.
Can not be glued to. In other words, in the step of forming the insulating film 9 by the transfer process, the plurality of metal caps 3 can be simultaneously processed, so that the insulating film 9 can be formed easily and with high productivity.

The step of adhering the metal cap 3 to the upper surface of the substrate 2 using an insulating adhesive is described in, for example, JP-A-11-121916 and JP-A-11-1.
It can be carried out by using a known method disclosed in Japanese Patent No. 26961.

In the above embodiment, the insulating film 9 was formed on the opening end face 3b of the metal cap 3 and in the vicinity thereof. However, in the method of manufacturing the conductive cap according to the present invention,
An insulating film may be formed on the upper surface of the metal cap 3. That is, as shown in FIGS. 5A to 5C, the insulating film 9b may be formed on the upper surface 3e of the metal cap 3. By forming the insulating film 9b on the upper surface of the metal cap 3 in this manner, it is possible to reliably prevent a short circuit due to contact with other components of the conductive component 1 with a cap or a wire.

In the above-described embodiment, an example in which the electronic component with a cap is applied to a chip type piezoelectric resonance component in which the piezoelectric element 4 shown in FIG. 1 is housed is shown. The present invention can be applied to an electronic component with an appropriate cap in which an electronic component element is housed in a package structure including a cap. That is, as the electronic component element, an electronic component element other than the piezoelectric element may be used.

Although the metal cap 3 is shown as the conductive cap, instead of the metal cap 3, a conductive film is formed on the surface of the cap made of an insulating ceramic such as alumina or an insulating material such as synthetic resin. The conductive cap may be used.

[0043]

In the conductive cap according to the present invention, since the insulating film is formed on the end face of the lower opening and on the inner and outer side surfaces connected to the end face in the vicinity of the end face, the conductive cap is placed on the upper surface of the terminal electrode. When the upper surface of the substrate on which is formed is bonded using an insulating adhesive, it is possible to reliably prevent a short circuit between the conductive cap and the terminal electrode.

Further, in the conventional electronic component with a cap in which the insulating film is formed on the substrate, it becomes difficult to form the insulating film with high precision as the size becomes smaller, which hinders the size reduction. . On the other hand, when the conductive cap according to the present invention is used, it is not necessary to form an insulating film on the substrate, and thus it is possible to easily cope with miniaturization.

When the insulation resistance between the open end surface of the conductive cap and the outer surface of the insulating film is at least 10 ⁹ Ω, a short circuit between the conductive cap and the terminal electrode on the substrate can be more reliably prevented. be able to.

The thickness of the insulating film is 4 μm to 25 μm.
When the thickness is in the range of μm, as described above, the electrical insulation between the conductive cap and the terminal electrode can be reliably achieved, and the increase in size of the substrate can be avoided. The restriction on the size of the electronic component element to be housed is also reduced.

When the vicinity of the opening end surface of the conductive cap is viewed in a cross section in a direction orthogonal to the circumferential direction of the conductive cap, the opening end surface and the inner side surface connected to the opening end surface form one curve. Curvature radius R of the curve is 80 to 150 μm
In the case of the range, the insulating film having a sufficient thickness can be reliably formed in the vicinity of the opening end face, and thereby the short circuit between the terminal electrode and the conductive cap can be more reliably achieved.

In the electronic component according to the present invention, the electronic component element is fixed on the substrate, the electronic component element is electrically connected to the plurality of terminal electrodes on the substrate, and the electronic component element is surrounded. As described above, since the conductive cap according to the present invention is bonded to the substrate from its opening side with an insulating adhesive, the insulating film provided on the conductive cap ensures a short circuit between the conductive cap and the terminal electrode. Can be prevented.

In the electronic component according to the present invention, when a piezoelectric element is used as the electronic component element, it is possible to reliably prevent a short circuit between the conductive cap and the terminal electrode on the substrate as described above, which is excellent in reliability. A piezoelectric component can be provided.

[0050]

[0051]

[Brief description of drawings]

1A and 1B are a cross-sectional view showing an electronic component with a cap according to an embodiment of the present invention and a partially cutaway enlarged cross-sectional view showing an enlarged tool thereof.

2A to 2C are perspective views showing a conductive cap used in an electronic component with a cap according to an embodiment of the present invention, and a cut portion taken along line AA in FIG. 2A. End view and bottom view.

FIG. 3 is a bottom view showing a state where a conductive cap is held by a holder in one embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a step of forming an insulating film on a conductive cap by a transfer method according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a conductive cap according to another embodiment of the present invention, an end face view and a bottom view of a cutting portion taken along the line AA in (a).

FIG. 6 is a perspective view for explaining an example of a conventional electronic component with a cap.

FIG. 7 is a vertical sectional view showing an example of a conventional chip-type piezoelectric resonance component.

[Explanation of symbols]

1 ... Electronic parts with cap 2 ... Substrate 2a ... top surface 3 ... Metal cap 4 ... Piezoelectric element 5, 6 ... Terminal electrodes 7, 8 ... Conductive bonding agent 9 ... Insulating film 9A ... Insulating film forming resin layer

Front page continued (72) Inventor Jiro Inoue, 26-10 Tenjin, Nagaokakyo, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor, Shoichi Kawabata 26-10 Tenjin, Nagaokakyo, Kyoto Stock Company Murata Manufacturing (56) Reference JP-A-8-111627 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 23/02 H01L 23/06 H03H 3/02 H03H 9 / 02

Claims (7)

(57) [Claims] 1. An insulating adhesive bond is provided to a top surface of the substrate from the opening side so as to surround an electronic component element mounted on the top surface of the substrate having at least a terminal electrode formed on the top surface. A conductive cap for an electronic component, which is fixed by an agent , characterized in that an insulating film is formed on the end face of the opening and on the inner and outer side faces connected to the end face in the vicinity of the end face. 2. The conductive cap according to claim 1, wherein the insulation resistance between the open end surface of the conductive cap and the outer surface of the insulating film is at least 10 ⁹ Ω. 3. The insulating coating has a thickness of 4 μm to 25 μm.
The conductive cap according to claim 1 or 2, wherein the conductive cap is in the range. 4. When the vicinity of the opening end face of the conductive cap is viewed in a cross section in a direction orthogonal to the circumferential direction of the conductive cap, the opening end face and the inner side surface connected to the opening end face form one curve. And the radius of curvature R of the curve is 80 μm
The conductive cap according to any one of claims 1 to 3, wherein the conductive cap is in the range of 150 m. 5. A substrate having at least an upper surface on which a plurality of terminal electrodes are formed, an electronic component element fixed on the substrate and electrically connected to the plurality of terminal electrodes, and an opening downwardly. has, in the opening end surface and its vicinity and the insulating coating is formed, an insulating contact from the opening side to said substrate
An electronic component, comprising: a conductive cap joined by a binder. 6. The electronic component according to claim 5, wherein the electronic component element is a piezoelectric element. 7. The electronic component according to claim 5, wherein the conductive cap is a metal cap.