JP4766239B2 - Ceramic electronic component and method for manufacturing the same - Google Patents

Description

  The present invention relates to a ceramic electronic component and a manufacturing method thereof.

  In a ceramic electronic component, a metal piece may have to be joined to the electrode. In such a case, as a joining means, in addition to the connection by solder, for example, laser welding as described in Patent Document 1 is performed. Applicable. According to laser welding, when the ceramic body is relatively thick, the output power of the laser can be increased, and the metal piece can be efficiently welded to the electrode in a short time.

  However, when the ceramic body becomes a thin ceramic electronic component of 2 to 3 mm or less, it is extremely difficult to laser weld the metal piece to the electrode without damaging, damaging or destroying the ceramic body. Become.

By reducing the output power of the laser, it is possible to avoid damage such as damage, breakage, or destruction to the ceramic body, but doing so will result in imperfect bonding and reliability of the bonding. This causes problems such as a reduction in work efficiency.
JP-A-9-213230

  An object of the present invention is to provide a highly reliable ceramic electronic component in which a metal piece is firmly bonded to an electrode without giving damage such as damage, breakage, or destruction to a ceramic body.

  Still another object of the present invention is to provide a manufacturing method suitable for manufacturing the above-described ceramic electronic component.

  In order to solve the above-described problem, a ceramic electronic component according to the present invention includes a ceramic element and a metal piece. The ceramic element has an electrode on at least one surface of a ceramic body. The metal piece is joined to the electrode of the ceramic element by laser welding.

  As described above, laser welding on the ceramic element described above is extremely difficult to laser-weld a metal piece to an electrode without damaging, damaging, or destroying the ceramic body. .

  As a result of diligent research to solve this problem, the inventors of the present invention are directly related to the bonding ratio of the electrodes and metal pieces, and as the melting ratio increases, the ceramic body is damaged. It has been found that the risk of causing damage such as breakage or destruction increases.

  Since the melting ratio is determined by the ratio between the thickness T1 of the electrode and the thickness T2 of the metal piece, the metal piece is used in order to achieve good bonding without damaging, damaging or breaking the ceramic body. It is extremely important how to select the thickness T2.

  According to experiments, it has been found that if the thickness T2 of the metal piece is 20 times or less the thickness T1 of the electrode, the metal piece can be reliably bonded to the electrode without breaking or damaging the ceramic body. .

  More preferably, the thickness T2 of the metal piece is not more than 10 times the thickness T1 of the electrode. Within this range, the melting ratio of the electrode and the metal piece is further approximated, so that it becomes more difficult to break or damage the ceramic body.

  INDUSTRIAL APPLICABILITY The present invention is effective in preventing destruction and damage of a ceramic body in a ceramic electronic component having a ceramic body thickness of 2 mm or less. In such a thin ceramic element, since the mechanical strength of the ceramic body is extremely low, the ceramic element is susceptible to damage such as damage, breakage or destruction due to a difference in melting rate. Even in the case of such a thin ceramic body, the above-mentioned problems can be avoided.

  A specific example or a representative example of a ceramic electronic component to which the present invention is applied is a ring varistor. The ring varistor has an important application as a noise absorbing element that absorbs noise generated in the commutator of a small DC motor. In that case, a metal piece made of a thin metal plate is joined to the electrode of the ring varistor, A structure in which a commutator connection piece (riser) is connected to the metal piece may be employed. In such a case, the present invention can be applied in joining the metal piece to the electrode of the ring varistor. However, the present invention is not limited to ring varistors.

  The present invention further discloses a manufacturing method suitable for manufacturing the above-described ceramic electronic component.

  As described above, according to the present invention, it is possible to provide a highly reliable ceramic electronic component in which a metal piece is firmly joined to the electrode without breaking or damaging the ceramic body.

  Other features of the present invention and the operational effects thereof will be described in more detail by way of examples with reference to the accompanying drawings.

  FIG. 1 is a plan view of a ring varistor as a specific example of a ceramic electronic component, and FIG. 2 is an enlarged partial sectional view of the ring varistor shown in FIG. The illustrated ring varistor includes a varistor element 40 and metal pieces (tabs) 51 to 53. The varistor element 40 has a center hole 45 through which a rotating shaft of a small DC motor passes, and corresponds to the number of armature poles of the small DC motor on one surface of a varistor element body 41 formed in an appropriate shape such as an annular shape. The plurality of electrodes 42 to 44 are provided. The electrodes 42 to 44 are provided with insulating gaps G1 to G3. In the drawing, only three electrodes 42 to 44 are shown, but the number is selected according to the number of armature poles of the small DC motor.

  The metal pieces 51 to 53 are made of a metal material having good electrical conductivity, typically, a thin plate mainly composed of Cu. Since the metal pieces 51 to 53 are connected to the riser later, a structure suitable for the metal pieces is provided. For example, in the case of the figure, the outer end portions of the metal pieces 51 to 53 are projected outward from the outer periphery of the varistor element 40, and this outer end portion is used for the riser connection.

The metal pieces 51 to 53 are joined to the electrodes 42 to 44 of the ceramic element 40 by laser welding 21 to 23. It is preferable that a plurality of laser welds 21 to 23 are provided at intervals in each plane of the metal pieces 51 to 53. As for the metal pieces 51-53, what has copper as a main component is desirable from the viewpoint of the electroconductivity. Copper itself, a copper alloy, or a surface having a plating film or the like may be used. When the metal pieces 51 to 53 are mainly composed of copper, a YAG laser (wavelength 1064) is used as a laser to be used.
nm) is a green laser with a short wavelength (wavelength 632 nm).

  Furthermore, you may have a conductive adhesive layer between the metal pieces 51-53 and the electrodes 42-44. Even if laser welding 21 to 23 is performed at a plurality of points, it must be in a spot shape, so that it is possible to make up for the lack of laser welding by using a conductive adhesive layer as an auxiliary.

  In the laser welding 21 to 23, as shown in FIG. 3, the irradiation head 1 of the laser device is directed to the surface of the metal pieces 51 to 53, the laser LA is applied to the metal piece with a predetermined wavelength, energy and emission diameter. Irradiate 51-53.

  In the laser welding 21 to 23 on the ceramic element 40 described above, the ceramic body 41 has such a degree that the melting ratio of the electrodes 42 to 44 and the metal pieces 51 to 53 is directly related to the quality of the joining, and the melting ratio is different. In addition, there is an increased risk of damage such as damage, breakage or destruction. The melting ratio is determined by the ratio between the thickness T1 of the electrodes 42 to 44 and the thickness T2 of the metal pieces 51 to 53. Therefore, it is extremely important how to select the thickness T2 of the metal pieces 51 to 53 in order to achieve good bonding without giving damage such as damage, breakage or destruction to the ceramic body 41. .

  According to the experiment, if the thickness T2 of the metal pieces 51 to 53 is not more than 20 times the thickness T1 of the electrodes 42 to 44, the metal pieces are applied to the electrodes 42 to 44 without breaking or damaging the ceramic body 41. It turned out that 51-53 can be joined reliably.

  More preferably, the thickness T2 of the metal pieces 51 to 53 is 10 times or less the thickness T1 of the electrodes 42 to 44. If it is this range, since the melting ratio of the electrodes 42-44 and the metal pieces 51-53 will be further approximated, it will become difficult to destroy and damage the ceramic element body 41. In a typical example where the thickness T1 of the electrodes 42 to 44 is around 10 μm, the thickness T2 is 100 μm or less, preferably 70 μm or less, and more preferably 50 μm or less. The lower limit value of the thickness T2 is determined by the function to be performed by the metal pieces 51 to 53. Generally, a thickness of 10 μm or more is necessary.

  The present invention is effective in preventing destruction and damage of the ceramic body 41 in a ceramic electronic component having a thickness T0 (see FIGS. 2 and 3) of the ceramic body 41 of 2 mm or less. In such a thin ceramic element 40, since the mechanical strength of the ceramic body 41 is extremely low, it is susceptible to damage such as damage, breakage, or destruction due to a difference in melting rate. Therefore, the present invention is applied. Thus, even in the case of such a thin ceramic body 41, the above-described problems can be avoided.

Next, an example is given and it demonstrates concretely.
Example 1
Metal pieces 51 to 53 were placed on the electrodes 42 to 44 of the ring varistor and welded using a laser device. Conditions concerning the laser device, the electrodes 42 to 44 of the ring varistor, and the metal pieces 51 to 53 are as follows.
<Laser device>
Equipment and optical fiber: ML-8050A, SI type Φ0.3
Output unit: Standard output unit f60 f60 (imaging ratio 1: 1)
Welding conditions: 0.8kW x 0.5ms rectangular wave
Processing point output energy 0.3J
The processing point output energy was set to an optimal value in a timely manner within a range of 0.3 J to 1.0 J depending on the thickness of the metal piece.
<Ceramic electronic parts>
In the ring varistor shown in FIG. 1, the electrodes 42 to 44 are copper patterns having a thickness T1 of 10 μm.
<Metal pieces 51-53>
The thickness T2 was made of a copper foil having a thickness of 50 μm.
Example 2
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 70 μm were used.
Example 3
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 100 μm were used.
Example 4
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 200 μm were used.
Comparative Example 1
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 250 μm were used.

Example 5
The metal pieces 51 to 53 are laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the electrodes 42 to 44 having a thickness T1 of 5 μm and the metal pieces 51 to 53 made of copper foil having a thickness T2 of 50 μm are used. 21-23.
Example 6
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 5 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 70 μm were used.
Example 7
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 5 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 100 μm were used.
Comparative Example 2
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 5 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 150 μm were used.

Example 8
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 1 except that the electrodes 42 to 44 having a thickness T1 of 15 μm and the metal pieces 51 to 53 made of copper foil having a thickness T2 of 100 μm were used. 21-23.
Example 9
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 8, except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 150 μm were used.
Example 10
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 8 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 300 μm were used.
Comparative Example 3
The metal pieces 51 to 53 were laser welded to the electrodes 42 to 44 in the same manner as in Example 8 except that the metal pieces 51 to 53 made of copper foil having a thickness T2 of 500 μm were used.

  Table 1 shows the results of examining the appearance of the ring varistors obtained in Examples 1 to 10 and Comparative Examples 1 to 3 described above, the bonding strength, and the presence or absence of damage to the ceramic body 41.

  The quality of the appearance is evaluated by visual inspection of the weld appearance of the ring varistor. A very beautiful weld finish is indicated by a circle, and some of the weld points are poor. Those with bad marks are indicated by crosses.

  When the copper pieces constituting the electrodes 42 to 44 are peeled off together with the metal pieces 51 to 53 when the metal pieces 51 to 53 are peeled off, the metal pieces 51 to 53 are firmly bonded to the electrode 42. It is evaluated that it is joined to .about.44, marked with .largecircle., And a case where some of the welding points were not peeled off together with the metal pieces is marked with .DELTA .. When the copper pattern which comprises the electrodes 42-44 is not stripped off with the metal pieces 51-53, it displays as x mark.

  The damage to the ceramic body 41 was evaluated by visually observing whether the ceramic body 41 has a laser hole. The case where the laser hole could not be confirmed is indicated by ◯, and the case where it was confirmed is indicated by ×.

As shown in Table 1, Comparative Examples 1 to 3 had poor welding finish, and when the metal pieces 51 to 53 were peeled off, the metal pieces 51 to 53 were separated from the electrodes 42 to 44 and peeled off. In the ceramic body 41, laser holes were observed at portions corresponding to laser irradiation.

  In contrast, all of Examples 1 to 3 and 5 to 9 showed a very beautiful weld finish. Further, when the metal pieces 51 to 53 are peeled off, the copper patterns constituting the electrodes 42 to 44 are peeled off together with the metal pieces 51 to 53, and the metal pieces are separated from the copper patterns constituting the electrodes 42 to 44. It was confirmed that 51-53 were joined firmly. Further, no laser hole could be confirmed in the ceramic body 41.

  Furthermore, in Example 4, in contrast to Examples 1 to 3 and 5 to 9, although the adhesive strength was inferior, results of inferior appearance and element damage were obtained. Moreover, although Example 10 is somewhat inferior in terms of appearance, bonding strength, and substrate in comparison with Examples 1 to 3 and 5 to 9, appearance, bonding strength, and substrate damage are compared with those in Comparative Examples 1 to 3. Good evaluation was obtained in all of the above.

  As is apparent from Table 1, when the metal piece thickness is 20 times or less of the electrode thickness, a practically no problem is obtained, and when the metal piece thickness is 10 times or less, there is no variation in the bonding strength.

  Further, if the thickness of the metal piece exceeds 100 μm, the optimum condition range for welding tends to be narrowed, and it is more preferable to make the metal piece 100 μm or less in order to perform uniform welding at all joint points.

  The laser used for laser welding 21-23 needs to be selected according to the material of the metal pieces 51-53 and the electrodes 42-44 to be welded. When the metal pieces 51 to 53 and the electrodes 42 to 44 are mainly composed of copper, a green laser having a shorter wavelength than the YAG laser is suitable. The experimental results using a YAG laser and a green laser (YAG-SHG) are shown below.

As shown in Table 2, when a YAG laser having a wavelength of 1064 nm is used, even if the output energy is adjusted, copper is originally low in the fundamental wave absorptivity of the YAG laser. However, if the output energy is forcibly increased, there is a problem that a hole is formed in the ceramic body 41.

  On the other hand, when a green laser with a wavelength of 632 nm is used, the copper absorptance for this wavelength reaches about five times the absorptivity of the YAG laser, so that no holes are generated in the ceramic body 41. The metal pieces 51 to 53 and the electrodes 42 to 44 can be joined.

  Next, although not the subject of the present invention, a small DC motor which is an example of use of a ring varistor that falls within the category of the ceramic electronic component according to the present invention will be described with reference to FIG.

  FIG. 4 is a partial sectional view showing a part of a small DC motor using the ring varistor according to the present invention as a noise absorbing element. In the small DC motor 6, a stator (field) 62 is provided inside the exterior body 61, and an armature 63 is arranged inside the stator 62. A plurality of commutator pieces 65 divided according to the number of poles of the armature 63 are coaxially arranged on the rotating shaft 64 attached to the armature 63. The armature 63 is insulated from the rotating shaft 64 by an insulator 66.

  Each of the commutator pieces 65 has a riser 67 that rises in the direction of the rotation diameter at one end on the armature 63 side, and an armature winding 68 is attached to the riser 67 with a bonding material 69 or the like. Connected by means of.

  The noise absorbing element 4 is mounted on the surface of the riser 67 opposite to the surface facing the armature 63 in a state of facing. The noise absorbing element 4 is the ring varistor shown in FIGS. The riser 67 connected to the commutator piece is connected to the metal pieces 51 to 53.

  Since the metal pieces 51 to 53 and the electrodes 42 to 44 are joined by the laser welding 21 to 23, the noise absorbing element 4 is joined to the riser 67 in a parallel state without causing an inclination. become.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

It is a top view of the ring varistor which concerns on this invention. It is an expanded partial sectional view of the ring varistor shown in FIG. It is a figure explaining the manufacturing method of the ring varistor which concerns on this invention. It is a fragmentary sectional view showing a part of small DC motor which used the ring varistor concerning the present invention as a noise absorption element.

Explanation of symbols

21-23 Laser welding
4 Ring Varistor 42-44 Electrode 51-53 Metal Piece

Claims (4)

A ceramic electronic component comprising a ring varistor including a ceramic element and a plurality of metal pieces and used as a noise absorbing element for a motor,
The ceramic element is a ring-shaped varistor element having a central hole through which the rotation shaft of the motor passes, and has a plurality of electrodes corresponding to the number of armature poles of the motor on at least one surface of the ceramic body. And
Each of the electrodes is disposed around the central hole with an insulating gap therebetween;
Each of the metal pieces is composed of a thin plate mainly composed of copper, and one surface is joined to each of the electrodes of the ceramic element by laser welding ,
Each other surface of the metal piece is a surface connected in a state of facing the riser extending in the direction of the rotation diameter from the commutator piece of the motor,
The thickness T2 of the metal piece is not more than 10 times the thickness T1 of the electrode and not more than 100 μm,
The ceramic body has a thickness of 2 mm or less,
Ceramic electronic components.   The ceramic electronic component according to claim 1, further comprising a conductive adhesive layer between the metal piece and the electrode. A method of manufacturing a ceramic electronic component according to claim 1 or 2,
Placing the metal piece on the electrode surface of the ceramic element having an electrode on at least one surface of the ceramic body;
Next, the metal piece is irradiated with a green laser, and the metal piece is welded to the electrode.
A manufacturing method including a process. A motor having a noise absorbing element, a commutator piece, and an armature,
The noise absorbing element is a ceramic electronic component according to claim 1 or 2 ,
The commutator piece has a riser extending in the direction of the rotation diameter at one end on the armature side, and the winding of the armature is connected to the riser,
The ceramic electronic component is joined in a state where the other surface of the metal piece faces the surface of the riser opposite to the surface facing the armature,
motor.