JP2015065207A - Ceramic substrate end face electrode for surface-mounted electronic component - Google Patents

Abstract

When soldering an end face electrode formed on a multilayer ceramic substrate and a set substrate, the end face electrode and the inner layer electrode are more reliably electrically connected even if the edge portion of the end face electrode is corroded by solder and disconnection occurs. Conduct.
In a ceramic substrate end face electrode 3 for a surface mount type electronic component, the end face electrode 3 provided on an edge portion E of the ceramic substrate 2 is an inner layer electrode 5 formed in a through hole in the ceramic substrate 2. Are electrically connected by the inner layer electrode 6 for connection.
[Selection] Figure 1

Description

  The present invention relates to an end face electrode of a ceramic substrate of a surface mount electronic component, and in particular, an inner layer electrode for connection is provided between the end face electrode and the inner layer electrode, thereby preventing electrical non-conductivity / defect between the electrodes. The present invention relates to a lost ceramic substrate end face electrode.

  Surface-mounted electronic components, such as surface-mounted crystal oscillators, are small and light, and are therefore widely used as frequency and time reference sources, particularly in portable electronic devices such as mobile phones. .

  As schematically shown in FIG. 8A, a surface-mounted crystal oscillator 21 using a conventional multilayer ceramic substrate for a base 22 is provided with an end face provided at an edge portion E on the outer bottom surface of the base 22. The electrode 23 and the connection electrode 24 provided on the upper surface of the multilayer ceramic substrate constituting the base 22 are electrically connected by an inner layer electrode 25 provided in a via hole (through hole) formed through the base 22 in the thickness direction. Is conducting.

 However, as schematically shown in FIG. 8B, the end face electrode 23 is connected to an external interface, for example, a circuit board (set board), for electrical connection of members constituting the surface-mounted crystal oscillator 21. When soldering, the metal portion of the edge portion E is usually formed thinner than the other portions, and the metal portion is made of a metal material that is easily eroded by solder, such as silver palladium. , Cracks C and the like are likely to occur in the edge portion E.

  As a result, problems such as electrical non-conduction and failure between the end face electrode 23 and the inner layer electrode 25 and an increase in series resistance shown in FIG.

  Therefore, conventionally, as shown in FIG. 9, when solder 38 is applied to the set substrate 37 at the substrate edge portion E between the multilayer ceramic substrate 32, the electrode pads 33 provided on the outer bottom surface thereof, and the side surface open through holes 35. Even if the side open through hole 35 is eroded by solder, the electrode pad 33 and the side open through hole 35 are electrically connected through the via hole 34 and the wiring layer 36 in the multilayer ceramic substrate 32. Thereby, even if the electrode pad 33 is disconnected due to erosion or the like, the electrical connection between the electrode pad 33 and the side surface open through hole 35 is maintained, and electrical non-conduction between the two is avoided.

  However, even with such a proposal, the end face electrodes and the inner layer electrodes of the plurality of ceramic substrates constituting the base of the surface-mount type crystal oscillator are more reliably electrically connected in the vertical direction to the main surface of the ceramic substrate. Was still difficult.

JP-A-9-330991 JP 2000-36713 A

  The problem to be solved by the present invention is that when soldering the end surface electrode of the multilayer ceramic substrate and the set substrate, the edge portion of the end surface electrode is corroded by the solder, and even if disconnection occurs, the end surface electrode and the inner layer electrode are connected. It is to make electrical conduction more reliable.

  In order to solve the above-described problems, according to the present invention, in the ceramic substrate end surface electrode for a surface mount electronic component, the end surface electrode formed on the edge portion of the ceramic substrate is formed in the through hole of the ceramic substrate. The inner layer electrode is electrically connected to the connecting inner layer electrode.

  In the present invention, the pair of inner layer electrodes for connection extend from the inner layer electrode to the inner surface of the end surface electrode so as to be orthogonal to the horizontal direction.

  Furthermore, in the present invention, the ceramic substrate is a multilayer ceramic substrate.

  Furthermore, in the present invention, the ceramic substrate has a rectangular shape in plan view, and the end surface electrodes are formed at four corners of the ceramic substrate, respectively.

  In the present invention, each end face electrode formed on the adjacent multilayer ceramic substrate is electrically connected by the inner layer electrode and the connection inner layer electrode formed on the adjacent ceramic substrate.

  The end surface electrode of the ceramic substrate and the inner layer electrode formed in the ceramic substrate can be reliably electrically connected.

1 shows a schematic cross-sectional structure of a surface mount type crystal oscillator provided with a ceramic substrate end face electrode according to an embodiment of the present invention, and shows a schematic cross-sectional structure, wherein (a) shows a state before the end face electrode is disconnected, and (b) ) Shows a schematic cross-sectional structure of the state after the end face electrode is disconnected. It is a perspective view of the whole structure of the crystal oscillator which is an Example of the surface mount type electronic component of this invention shown in FIG. FIG. 3 is a detailed longitudinal sectional view of the entire structure of the surface-mount type crystal oscillator shown in FIG. 2. FIG. 4 is a plan view of the surface-mounted crystal oscillator shown in FIG. FIG. 4 is a plan view of the surface-mounted crystal oscillator shown in FIG. It is the top view seen in the C arrow imaginary plane of the surface mount type crystal oscillator shown in FIG. FIG. 4 is a plan view of the surface-mount type crystal oscillator shown in FIG. 1 shows a schematic cross-sectional structure of a surface-mount type crystal oscillator provided with a conventional ceramic substrate end face electrode with a metal cover removed, where (a) shows a state before the end face electrode is broken, and (b) shows an end face electrode. It is sectional drawing which shows a general | schematic cross-section structure of the state after said disconnection had arisen. FIG. 6 is a partial longitudinal sectional view of a conventional example in which an inner layer electrode and an end surface electrode are electrically connected by a wiring layer in order to cope with an electrical disconnection between an electrode pad portion and an end surface electrode.

  Hereinafter, an electrode for a ceramic substrate for a surface-mounted crystal oscillator which is an embodiment of the surface-mounted electronic component of the present invention will be described with reference to the accompanying drawings.

  As schematically shown in FIG. 1 (a), the surface mount crystal oscillator 1 using the multilayer ceramic substrate of the present invention as a base 2 is shown as a base section (here, the metal cover is removed). An end face electrode 3 having an L-shaped vertical cross section composed of an end face and a bottom face provided on the edge portion E of the outer bottom face 2; a connection electrode 4 provided on the upper face of the multilayer ceramic substrate constituting the base 2; Are electrically connected and conducted by an inner layer electrode 5 provided in a via hole (through hole) formed so as to penetrate in the thickness direction.

  In the surface mount type crystal oscillator 1 according to the embodiment of the present invention, the edge portion E of the end face electrode 3 is eroded particularly during soldering, and the edge portion E is cracked as shown in FIG. In order to maintain electrical continuity between the end face electrode 3 and the inner layer electrode 5 even when C or the like occurs, the inner end face of the end face electrode 3 and the inner layer electrode 5 are connected in the horizontal direction, and both are electrically connected. A connection inner layer electrode 6 to be connected is additionally provided.

Thus, by additionally providing the inner layer electrode 6 for connection,
Even if a defect or the like is generated on the outer surface of the end face electrode 3, electrical conduction between the end face electrode 3 and the inner layer electrode 5 is maintained. As a result, a low resistance value in the wiring layer can be maintained, and the end face electrode can be maintained. The mechanical strength of 3 can be increased.

  FIG. 2 shows the surface of the embodiment of the present invention in which the crystal oscillator is sealed by covering the base 2 made of a multilayer ceramic substrate with the metal cover 7 and welding or soldering the outer edge of the metal cover 7 to the base 2. 1 is a perspective view of a mounting type crystal oscillator 1. FIG.

  Furthermore, the surface mount type crystal oscillator 1 using the ceramic substrate end face electrode of the embodiment of the present invention, for example, a module product such as TCXO, OCXO, etc., has a specific configuration as shown in FIG. The base 2 made of a multilayer ceramic substrate having a rectangular shape in plan view on which the inner layer electrode 5, the connecting inner layer electrode 6 and the electronic component unit 8 to be described later are disposed, and the crystal oscillator 8 It consists of a metal cover 7 which is sealed and stored inside.

  As shown in FIG. 3, the base 2 made of a multilayer ceramic substrate is composed of, for example, ceramic substrates 2a, 2b and 2c having a three-layer structure. Note that the multilayer ceramic substrate is not limited to three layers, and may be composed of more layers, for example, five layers of ceramic substrates as required.

  On the first ceramic substrate 2a, as shown in FIG. 4 which indicates a virtual plane as viewed in the direction of arrow A, single electronic components 8a and 8b such as a chip capacitor, a chip resistor, an IC, a crystal resonator, and a ceramic oscillator It is electrically connected to the inner layer electrodes 5a, 5b, 5c, 5d via the connection electrodes 4a, 4b, 4c, 4d.

  Further, the second ceramic substrate 2b is electrically connected to inner layer electrodes 5a, 5b, 5c and 5d provided on the first ceramic substrate 2b as shown in FIG. Connection electrodes 4e, 4f, 4g and inner layer electrodes 5e, 5f, 5g, 5h, 5i, 5j, 5k are disposed. Here, the inner layer electrode 5j is used as an inner layer pattern or a via for electrical connection to the electronic component units 8a and 8b or electrical connection to the electronic component units 8a and 8b. Further, end face electrodes 3a, 3c and inner layer electrodes 5e, 5k formed at the four corners of the second ceramic substrate 2b extending from the side surface of the third ceramic substrate 2c are orthogonal to the inner layer electrodes 5e, 5k. The electrodes 3a and 3c are mechanically and electrically connected by a pair of connecting inner layer electrodes 6a and 6b extending horizontally to the inner surfaces of the electrodes 3a and 3c.

  Here, the pair of connecting inner layer electrodes 6a, 6b are connected to extend from the inner layer electrodes 5e, 5k perpendicularly in the horizontal direction toward the inner surfaces of the end surface electrodes 3a, 3c. The inner layer electrodes 5e and 5f are mechanically and electrically connected to each other by the connection electrode 4e, the inner layer electrodes 5g and 5h are connected by the connection electrode 4f, and the inner layer electrodes 5i and 5g are connected by the connection electrode 4g, respectively. Has been.

  Furthermore, as shown in FIG. 6 indicating the virtual plane as viewed in the direction of arrow C in FIG. 3, inner layer electrodes 5l, 5m, 5n, and 5o are disposed on the main surface of the third ceramic substrate 2c. The inner layer electrodes 6c and 6d for connection extending perpendicular to the horizontal direction are connected to the end surface electrode 3c, and the inner layer electrode 5n is connected to the inner layer electrodes 6c and 6d for connection extending perpendicular to the horizontal direction. These are connected mechanically and electrically to the inner surface of the end face electrode 3, respectively.

  Here, the pair of connecting inner layer electrodes 6c and 6d are connected to extend from the inner layer electrodes 5l and 5n to the inner surfaces of the end surface electrodes 3a and 3c in a direction orthogonal to the horizontal direction. The internal electrodes 5l, 5m, 5n, 5o are used for electrical connection between an external terminal (user terminal) and an internal wiring pattern formed on a circuit (set) substrate.

  Also, as shown in the X arrow portion of FIG. 3, the end surface electrodes 3b and 3c are mechanically and electrically connected to the inner layer electrodes 5e and 5l by the inner layer electrodes 6a and 6c for connection. Even if the edge portion E of the end face electrodes 3b and 3c is deficient, it is electrically connected by the connecting inner layer electrodes 6a and 6c, so that no electrical non-conduction occurs between them. Similarly, no electrical non-conduction occurs in the end face electrodes 3a and 3d.

  Furthermore, as shown in FIG. 7 which indicates a virtual plane as viewed in the direction of arrow D in FIG. 3, the outer bottom surface of the third ceramic substrate 2 c has a longitudinal section extending over the three side surfaces of the edge portion E of the third ceramic substrate 2 c. L-shaped end face electrodes 3a, 3b, 3c, 3d are formed and extend to the side surface of the second ceramic substrate 2b as shown in FIG.

  Thus, in the ceramic substrate end face electrode of the surface mount type crystal oscillator which is an embodiment of the surface mount type electronic component of the present invention, each ceramic substrate other than the first ceramic substrate on which the crystal oscillator of the multilayer ceramic substrate is arranged and stored is used. Because the mechanical and electrical connection between the inner layer electrode and the end face electrode is ensured by a pair of additional inner layer electrodes for connection, the end face electrode formed on one ceramic substrate is completely peeled off. However, electrical conduction is maintained by the end face electrodes formed on the other ceramic substrate.

  Therefore, a highly reliable end face electrode for a surface mount type crystal oscillator can be obtained, and even if a crack or other defect occurs in the end face electrode, the electrical connection between the electrodes, particularly in the vertical direction of the multilayer ceramic substrate, is sufficiently maintained. In addition, the mechanical strength of the end face electrode is reliably maintained.

  As a result, miniaturization of a surface mount electronic component using a multilayer ceramic substrate, for example, a surface mount crystal oscillator, is achieved.

1. Surface mount electronic components (surface mount crystal oscillator)
2. Base 3. 3. End face electrode 4. Connection electrode Inner layer electrode 6. 6. Inner layer electrode for connection Metal cover8. Electronic components

Claims (5)

  In the ceramic substrate end surface electrode for surface mount type electronic components, the end surface electrode provided at the edge portion of the ceramic substrate is electrically connected to each other by the inner layer electrode formed in the through hole of the ceramic substrate and the inner layer electrode for connection. Ceramic substrate end face electrodes characterized by being connected to each other.   2. The ceramic substrate end face electrode according to claim 1, wherein the connecting inner layer electrode extends and is connected to the inner face of the end face electrode orthogonally from the inner layer electrode.   The ceramic substrate end face electrode according to claim 1, wherein the ceramic substrate is a multilayer ceramic substrate.   The ceramic substrate end surface electrode according to claim 1, wherein the ceramic substrate has a rectangular shape in plan view, and the end surface electrodes are formed at four corners of the edge portion of the ceramic substrate. 4. The ceramic substrate electrode according to claim 3, wherein each of the end surface electrodes formed on the adjacent multilayer ceramic substrate is electrically connected by the inner layer electrode formed on the adjacent ceramic substrate and the connection inner layer electrode.

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