JP5171228B2 - Crystal device for surface mounting - Google Patents

Description

  The present invention relates to a crystal device for surface mounting, and more particularly to a surface mounting device that facilitates alignment of a metal cover and prevents detachment.

  Surface mount devices such as crystal resonators (hereinafter referred to as surface mount resonators) are small and light, so they are incorporated into portable electronic devices typified by mobile phones together with an oscillation circuit as a frequency and time reference source. It is. One of them is one in which the open end face of the container body is sealed using a eutectic alloy.

(Example of conventional technology)
FIG. 4 is a diagram for explaining a conventional example. FIG. 4 (a) is a cross-sectional view of a surface-mounted vibrator, FIG. 4 (b) is a partially enlarged cross-sectional view of a portion indicated by a dotted line, and FIG. ) Is a plan view of the crystal piece.

  The surface-mounted vibrator is formed by housing a crystal piece 2 in a concave container body 1 and joining a metal cover 3 in a hermetically sealed manner. The container body 1 is made of a laminated ceramic having a bottom wall 1a and a frame wall 1b, and has a pair of crystal terminals 4 on the inner bottom surface and an external terminal 5 on the outer bottom surface. For example, a metal film 6 separated from the outer peripheral end is provided on the opening end surface (the upper surface of the frame wall 1b) of the container body 1.

  The metal film 6 is formed by printing with the base electrode 6a as W (tungsten) or Mo (molybdenum), baked together with the container body 1, and then plated with Ni and Au as the conductive layer 6b. The crystal terminal 4 is electrically connected to a pair of diagonal external terminals 5, and the metal film 6 is electrically connected to another set of external terminals 5 through a through hole or a laminated surface (not shown).

  The crystal piece 2 has excitation electrodes 7a on both main surfaces, and for example, extraction electrodes 7b extend on both sides of one end. Both sides of one end of the crystal piece 2 from which the extraction electrode 7 b extends are fixed to the crystal terminal 4 by the conductive adhesive 8. The metal cover 3 is made of Kovar (alloy of Fe, Ni, Co) whose thermal expansion coefficient is relatively close to that of ceramic, and the surface is provided with Ni plating (not shown), for example.

  A eutectic alloy 9 such as AuSn (gold tin) as a sealing material is fixed to the outer periphery of at least one main surface of the metal cover 3 by, for example, melting. The melting point (liquidus temperature) of the eutectic alloy (AuSn) 9 is about 278 ° C. Then, the metal cover 3 is positioned on the opening end surface of the container body 1 using a jig or the like (not shown), and the eutectic alloy 9 is heated and melted. Thereby, the outer periphery of the metal cover 3 is joined to the opening end face, and the crystal piece 2 is hermetically sealed.

In such a case, for example, the melting temperature (177 ° C.) is significantly lower than that of seam welding in which Ni (nickel, melting point: 1455 ° C.) of the metal cover 3 is melted and joined by Joule heat. Therefore, it is possible to prevent the container body 1 from being bent or broken due to the difference in thermal expansion coefficient between the metal cover 3 and the container body 1. Then, the inner product can be increased by reducing the width of the frame wall 1b. Furthermore, since the melting temperature is low, effects such as prevention of occurrence of splash during melting can be achieved. However, since Au is contained as the eutectic alloy 9, it becomes expensive.
JP 2001-102894 A JP 2005-184746 A Japanese Patent Laying-Open No. 2005-340661

(Problems of conventional technology)
However, in the surface mount vibrator having the above-described configuration, the metal cover 3 may protrude from the opening end surface due to positioning accuracy using a jig for positioning the metal cover 3 on the opening end surface of the container body 1. Therefore, in this case, the surface-mounted vibrator must be disposed of, including defective appearance, and productivity is reduced. Particularly, since the eutectic alloy 9 containing expensive Au is used, the loss is large.

  Further, the metal film 6 including the base electrode 6 a provided on the surface of the opening end face may be peeled off due to shrinkage after the eutectic alloy 9 is melted. In particular, in this example, there is a problem that the metal film 6 formed on the opening end face of the container body 1 is easily separated because it is separated from the outer peripheral end. In order to prevent the metal cover 3 from protruding from the outer peripheral end of the opening end face, for example, the metal film 6 is formed away from the outer peripheral end.

(Object of invention)
It is an object of the present invention to provide a surface-mount crystal device in which positioning of a metal cover is ensured and productivity is improved.

  According to the present invention, as shown in the claims (Claim 1), at least a crystal piece is accommodated in a container body having a rectangular shape in a plan view and having a bottom wall and a frame wall made of multilayer ceramic, A metal film having a base electrode is provided on the opening end face of the container body, a metal cover is bonded on the metal film apart from the outer peripheral end of the opening end face, and the crystal piece is hermetically sealed. In the quartz crystal device, a jetty for positioning the metal cover is provided on each of the four sides on the outer peripheral surface that is the outside of the metal cover of the opening end surface of the container body, and the jetty includes the outer peripheral edge of the outer peripheral surface. And it is set as the structure made lower than the height of the said metal cover.

  With such a configuration, the metal cover is positioned by the jetty provided on each of the four sides of the container body, so that the metal cover does not protrude from the opening end surface of the container body. Therefore, it is possible to prevent disposal due to poor appearance and the like and to improve productivity. In this case, needless to say, a jetty provided in a bowl shape at a pair of diagonal portions may be used.

  In Claim 2 of this invention, let the said jetty be a frame which goes around the outer periphery of the said opening end surface in Claim 1. Thereby, the structure in Claim 1 is made more concrete.

  In the third aspect of the present invention, in the first aspect, the jetty is fired by printing ceramic on the opening end face. Thereby, it can form integrally with baking with a container main body.

  In the fourth aspect of the present invention, in the first aspect, the base electrode is formed including an outer peripheral end of the opening end face, and the jetty is formed on the base electrode. As a result, the base electrode is pressed under the jetty, so that peeling of the eutectic alloy during thermal contraction is surely prevented.

  In the fifth aspect of the present invention, in the first aspect, the base electrode is formed to be separated from the outer peripheral end of the opening end surface and to expose the base of the container body, and the jetty is formed on the base electrode and the base. The This prevents the base electrode from peeling off as in the fourth aspect. And since a jetty is formed also on the ground surface of a container main body, joining strength can be raised.

  In the sixth aspect of the present invention, in the first aspect, the base electrode is formed so as to be separated from the outer peripheral end of the opening end surface and the base of the container body is exposed, and the jetty is formed on the base. Thereby, since the jetty is formed on the entire surface of the container main body, the joint strength can be further increased.

  According to a seventh aspect of the present invention, in the first aspect, the metal cover is bonded to the metal film on the opening end surface by heating and melting a eutectic alloy containing at least Au. As a result, the sealing means is further clarified, and the product containing Au is not discarded, which further increases productivity.

  FIG. 1 is a diagram for explaining a first embodiment of the present invention. FIG. 1 (a) is a sectional view of a surface-mounted vibrator, FIG. 1 (b) is a partially enlarged sectional view, and FIG. It is a partial cross section figure of a cylindrical container main body. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  As described above, the surface-mount vibrator accommodates the crystal piece 2 in the concave container body 1 made of the laminated ceramic having the bottom wall 1a and the frame wall 1b, and joins the metal cover 3 to the opening end face by the eutectic alloy 9. And sealed. The eutectic alloy 9 is AuSn and is provided on the outer periphery of the metal cover 3. The metal cover 3 is Ni plated with the base material being Kovar.

  And in this embodiment, the cyclic | annular frame as the jetty 10 is provided in the outer periphery of the opening end surface (frame wall 1b upper surface) used as the outer side of the metal cover 3 including an outer peripheral end. The jetty 10 (annular frame) functions as positioning with respect to the opening end face when the metal cover 3 is joined by heating and melting.

  In this embodiment, each container body 1 is divided by laminating a sheet-like bottom wall 1A and a frame wall 1B (not shown) made of ceramic fabric. For example, a base electrode 6a made of W or Mo is formed in advance on the entire surface including the inner and outer peripheral ends on the upper surface (opening end surface) of the sheet-like frame wall 1B (not shown) having the openings 11 in the vertical and horizontal directions. In this case, circuit patterns such as the crystal terminals 4 and the external terminals 5 are formed in the same manner.

  Next, the sheet-like jetty 10 is formed by printing in the central region of the metal film 6 excluding both sides of the frame width of the opening end face. The sheet-like frame wall 1B is laminated on the sheet-like bottom wall 1A, and is integrally fired including the base electrode 6a and the sheet-like jetty 10. Then, for example, Ni and Au as the conductive electrodes 6b are provided on the base electrode 6a by electroplating.

  Next, both sides of one end of the crystal piece 2 where the lead electrode 7b (not shown) extends are fixedly accommodated in the crystal terminal 4 provided on the inner bottom surface of each recess of the sheet-like container body 1 '. Next, the metal cover 3 is positioned on the opening end surface in the annular frame wall 1b (the jetty 10). And it carries in to the heating furnace which is not shown in figure, the eutectic alloy 9 of the metal cover 3 is heat-melted, and it joins to the opening end surface of each recessed part. Lastly, the center line AA of the jetty 10 provided on the opening end surface of the sheet-like container body 1 'is divided vertically and horizontally to obtain individual surface-mounted vibrators.

  In this example, in the state of the sheet-like container body 1 ′, the crystal piece 2 is accommodated in each recess and the metal cover 3 is joined. However, after the sheet-like container body 1 ′ is divided into individual container bodies 1, The crystal piece 2 may be accommodated and the metal cover 3 may be covered.

  With such a configuration, since the jetty 10 made of an annular frame is provided on the opening end surface of the container body 1, the metal cover 3 can be positioned on the opening end surface without using a special jig. Therefore, the metal cover 3 can be easily positioned, and the metal cover 3 does not protrude from the opening end surface. Therefore, since it does not become inferior goods including an external appearance defect etc., productivity can be improved. In particular, since the eutectic alloy 9 containing gold is not discarded, the cost can be reduced.

  In this case, the annular frame wall 1b (the jetty 10) is provided on the base electrode 6a provided on the surface including the outer peripheral edge of the opening end surface of the container body 1. Therefore, since the base electrode 6a is pressed under the jetty 10, it is possible to prevent the base electrode 6a from being peeled off due to shrinkage when the eutectic alloy 9 is melted.

(Second Embodiment)
FIG. 2 is a view of a surface-mounted vibrator for explaining a second embodiment of the present invention. FIG. 2A is a partially enlarged sectional view of the surface-mounted vibrator, and FIG. FIG. In addition, the same number is given to the same part as previous embodiment, and the description is simplified or abbreviate | omitted.

  In the second embodiment, the base electrode 6a on the opening end face of the container body 1 is formed away from the outer peripheral end and exposing the ceramic base. And the annular frame wall 1b as the jetty 10 is formed over the ceramic base of the opening end face and the base electrode 6a. Even in this case, the surface-mounted vibrator is formed in a sheet-like state as in the first embodiment, and the annular frame wall 1b is formed by printing and firing ceramics as described above.

  With such a configuration, the annular frame wall 1b (the jetty 10) functions as a positioning of the metal cover 3 in the same manner as described above. In this case, a portion closer to the outer periphery of the jetty 10 is directly bonded to the ceramic substrate, so that the bonding strength can be increased. Moreover, since a part near the inner periphery of the jetty 10 is bonded onto the metal film 6, the metal film 6 is prevented from being peeled when the eutectic alloy 9 is melted as described above.

(Third embodiment)
FIG. 3 is a view of a surface-mounted vibrator for explaining a third embodiment of the present invention. FIG. 3 (a) is a partially enlarged sectional view of the surface-mounted vibrator, and FIG. FIG. In addition, the same number is given to the same part as previous embodiment, and the description is simplified or abbreviate | omitted.

  In the third embodiment, the base electrode 6a on the opening end face of the container body 1 is formed farther away from the outer peripheral end than in the second embodiment, and the ceramic base is exposed. And the annular frame wall 1b as the jetty 10 is formed in the ceramic ground surface of an opening end surface. Even in this case, the surface-mounted vibrator is formed in a sheet shape, and the annular frame wall 1b is formed by printing and firing of ceramic.

  With such a configuration, the annular frame wall (the jetty 10) functions as the positioning of the metal cover 3 in the same manner as described above. In this case, since all of the jetty 10 are directly bonded to the ceramic substrate, the bonding strength can be further increased.

(Other matters)
In the above embodiment, the eutectic alloy 9 is AuSn. However, for example, AuGe (gold germanium) may be used as long as it is an eutectic alloy 9 containing Au. The eutectic alloy 9 containing Au can be substantially lower than the melting temperature of Ni. And although the eutectic alloy 9 was provided in the metal cover 3, you may provide it in the opening end surface of the container main body 1. FIG. Moreover, although the jetty 10 is an annular frame wall, it should be provided at least on each of the four sides.

  Moreover, it can be applied even when Ni of the metal cover 3 is required by seam welding instead of the eutectic alloy 9, for example. However, in this case, a metal ring for welding is not used, and so-called direct seam welding in which a thick film is formed by metallization is used. Further, although the surface-mount crystal device is a surface-mount resonator, it can also be applied to a surface-mount oscillator in which an IC chip and a crystal piece 2 are integrated.

4A is a cross-sectional view of a surface-mounted vibrator, FIG. 4B is a partially enlarged cross-sectional view, and FIG. 4B is a partial cross-sectional view of a sheet-like container body. FIG. 6 is a diagram for explaining a second embodiment of the present invention, in which FIG. (A) is a partially enlarged sectional view of a surface-mounted vibrator, and (b) is a partially sectional view of a sheet-like container body. It is a figure explaining 3rd Embodiment of this invention, The figure (a) is a partial expanded sectional view of a surface mount vibrator, The figure (b) is a partial sectional view of a sheet-like container main body. FIG. 1A is a cross-sectional view of a surface-mounted vibrator, FIG. 1B is a partially enlarged cross-sectional view of a portion indicated by a dotted line, and FIG. 1C is a crystal piece. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 Crystal piece, 3 Metal cover, 4 Crystal terminal, 5 External terminal, 6 Metal film, 7 Excitation and extraction electrode, 8 Conductive adhesive, 9 Eutectic alloy, 10 Jetty

Claims (2)

Housing at least the crystal piece and the bottom wall and the frame wall consisting of a ceramic and the in plan view a rectangular container body concave cross section formed by laminating, forming a metal film having a base electrode to the open end face of said container body In the crystal device for surface mounting formed by joining a metal cover on the metal film at a distance from the outer peripheral end of the opening end surface , and sealingly enclosing the crystal piece in the container main body , opening end face jetty for positioning the metal cover at least each side of the outer peripheral edge of the outer become periphery surface of the metal cover is provided with a low rather configuration than the height of the metal cover with the jetty surrounds the outer peripheral edge And the base electrode is formed so as to be separated from the outer peripheral end of the opening end surface and to expose the base of the container body, and the jetty is formed on the base electrode and the base Quartz crystal device for surface mounting, characterized in that it is. According to claim 1, wherein the metal cover, the metal film formed on said opening end surface, quartz crystal device for surface mounting to a eutectic alloy Ru joined heat-melted to include at least Au.

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