JP3864417B2 - Package for electronic components - Google Patents

Description

  The present invention relates to a surface-mount type electronic component package used in electronic equipment and the like, and more particularly, when a surface-mount type piezoelectric vibration device such as a crystal resonator, a crystal filter, or a crystal oscillator is bonded to a circuit board with a conductive bonding material. It improves the bonding stability.

  Examples of electronic components that require hermetic sealing include piezoelectric vibration devices such as crystal resonators, crystal filters, and crystal oscillators. Each of these products is hermetically sealed in order to form a metal thin film electrode on the surface of the crystal diaphragm and protect the metal thin film electrode from the outside air.

  Due to the demand for surface mounting of components, these piezoelectric vibration devices are increasingly being housed in a package made of a ceramic material. For example, Japanese Patent Application Laid-Open No. 2002-76813 discloses a ceramic material in which a base (mounting substrate) having a quartz vibration plate mounting portion and a cap (cover) having an inverted concave cross section are hermetically sealed. A configuration is disclosed in which a package to be mounted is mounted on a circuit board and bonded via a conductive bonding material such as solder.

Here, the terminal electrode is formed on the bottom surface of the base, and in order to confirm the connection state due to the solder rising, the terminal electrode is connected to the side surface from the bottom surface of the base by a castellation (through hole) formed on the side surface of the base. It extends to. In addition, because of the ease of processing and cost advantages, so-called glass epoxy substrates in which a mesh-like glass fiber is impregnated with an epoxy resin material are widely used as circuit boards. Paste solder is applied by a technique such as screen printing. The terminal electrode of the package is mounted on the electrode pattern of the circuit board, the paste solder is melted in a melting furnace, and the piezoelectric vibration device is soldered on the circuit board.
JP 2002-76813 A

  However, due to the difference in thermal expansion between the package and the circuit board, stress may be generated in the solder that joins them, and cracks may occur. In particular, when the package is made of a ceramic material such as alumina and the circuit board is made of a glass epoxy board, and is used for heat-resistant applications such as in-vehicle use, the package is placed in a high temperature environment and the thermal expansion coefficient of the package As a result, the circuit board has a large coefficient of thermal expansion, and fatigue breakdown is likely to occur from the solder. For this reason, the problem of solder cracks, which did not become a serious problem in a normal temperature environment, appeared remarkably in a high temperature environment, and there was a problem that peeling occurred from the solder crack portion when an impact was applied.

  In the above-mentioned patent document 1, in order to cope with these, a groove is formed between the terminal electrodes on the bottom surface of the base. However, the number of steps for processing the groove is increased and the cost is increased. The mechanical strength is reduced. Further, although the terminal electrode on the bottom surface of the base is formed only on one side, there is a problem that the mounting stability on the circuit board is poor and the circuit board is weak against stress such as warping.

  The present invention has been made to solve the above-described problems, and provides an electronic component package that improves the reliability of mounting and bonding of a package for an electronic component and a circuit board and is easy to process and inexpensive. It is intended.

  An electronic component package according to claim 1 of the present invention is a package for an electronic component comprising a flat rectangular base for holding an electronic component element and a cap for hermetically sealing the electronic component element, A pair of terminal electrodes are formed along opposite sides of the bottom surface of the base, and the pair of terminal electrodes is formed so as to be opposed to each other and to be formed with one terminal electrode not facing each other. And a pair of terminal electrodes of the base and the circuit board are bonded by a conductive bonding material.

  Further, in the above-described configuration, the pair of terminal electrodes are arranged symmetrically with respect to the center point of the base, and a region where one terminal electrode is not formed without facing each other is arranged at the corner of the base. Features.

  In the above configuration, the base is made of a ceramic material, the terminal electrodes are formed by metallization, and the circuit board is made of a glass epoxy board.

  In the above-described configuration, a bump made of the same material metallization is formed on a part of the terminal electrode.

  Further, in the above-described configuration, the extension dimension of the terminal electrode is formed to be 60% to 85% with respect to the base width dimension in the extending direction of the terminal electrode.

  According to the present invention, the pair of terminal electrodes formed on the bottom surface of the base has a region where the electrodes are formed facing each other and a region where one of the terminal electrodes which are not facing each other is not formed. For this reason, it is possible to prevent the electronic component package (base) from being twisted three-dimensionally on the circuit board while increasing the bonding strength with the circuit board by the opposing terminal electrode regions. The effect can be reduced. Further, even if a difference in thermal expansion occurs between the electronic component package (base) and the circuit board due to the presence of the region where one terminal electrode is not formed, the electronic component package is directed toward the region where the one terminal electrode is not formed. Since the stress of the (base) can be released, the stress is concentrated on the solder interposed between the electronic component package and the circuit board, so that fatigue failure is less likely to occur from the solder. Therefore, adverse effects such as solder cracks can be suppressed, and the reliability of mounting and bonding of the electronic component package and the circuit board can be improved.

  According to claim 2, in addition to the above-described effects, the pair of terminal electrodes are arranged symmetrically with respect to the center point of the base, and a region where one terminal electrode is not formed without facing each other Therefore, the directionality of the terminal electrode is lost and the mounting workability of the electronic component package is improved. In addition, even if there is a difference in thermal expansion between the electronic component package (base) and the circuit board, stress is released to the corner area where one terminal electrode of the pair of terminal electrodes is not formed. The stress is relaxed so as to rotate in a plane at the center point of the package (base). For this reason, stress can be more efficiently relaxed without bias, and the occurrence of solder cracks and the like can be remarkably suppressed.

  According to the third aspect of the present invention, in addition to the above-described effects, the stress of the electronic component package (base) can be obtained even if a package made of a ceramic material and a circuit board made of a glass epoxy board, which are highly influenced by thermal expansion, are combined. The crack is not generated in the solder interposed between the electronic component package and the circuit board. Further, since the structure of the terminal electrode capable of relaxing the stress of thermal expansion can be obtained by the conventional metallization technique without passing through a special processing step, it can be formed extremely easily and inexpensively.

  According to the fourth aspect, in addition to the above-described effects, the bump made of the same material metallization is formed on a part of the terminal electrode, so that the stress can be relieved more efficiently and the buffering effect is high. In addition, since the conductive bonding material accumulates in the gaps raised by the bumps and the bonding area increases, the bonding strength with the circuit board can be further increased. Also, bumps can be formed very easily and inexpensively by laminating the same metallization.

  According to claim 5, in addition to the above-described effects, the stress relaxation of the present invention is achieved by setting the extension dimension of the terminal electrode to 60% to 85% with respect to the base width dimension in the extending direction of the terminal electrode. Function to improve further.

The graph of FIG. 4 shows that the solder endurance test of the surface-mount type crystal resonator shown in the first embodiment (disclosed in FIGS. 1 to 3) is performed under the following conditions.
In the surface-mount type crystal unit, a cap made of alumina ceramic is sealed with a glass made of alumina ceramic having a short side of 2.5 mm and a long side of 3.2 mm, and a terminal electrode formed on the bottom surface of the base is tungsten metallized. A nickel plating was used, and a gold plating was applied on the top. In such a surface-mounted crystal resonator, as shown in FIG. 2, the dimension L1 of the terminal electrode in the base long side direction is set to A0.9 mm and B1.1 mm, and the terminal electrode in the base short side direction is set. Each of the dimensions L2 was increased by 5% from 30% to 90% with respect to the dimension W in the base short side direction (direction in which the terminal electrode extends) from the A line and the B line starting from each terminal electrode. A total of 26 samples were tested, namely 13 samples of A and 13 samples of B.
The circuit board is made of a glass epoxy material, and the electrode pad material is made of copper.
Eutectic solder (Pb37-Sn63) was used for the bonding of the surface-mounted crystal resonator and the circuit board.
The following environmental temperature test was performed on the surface-mounted crystal resonator bonded to the circuit board with solder. In an atmospheric pressure, the temperature is increased from −40 ° to + 125 °, and the temperature is decreased from + 125 ° to −40 ° as one cycle (the time of one cycle is 60 minutes). Solder cracks were confirmed by analysis and repeated up to 3000 cycles. And the test was stopped when the solder crack was confirmed on the way, and the number of cycles at that time was counted.
From these test data, in adopting the configuration of the present invention, the optimal effect is obtained by setting the extension dimension of the terminal electrode to 60% to 85% with respect to the base width dimension in the extending direction of the terminal electrode. It was found to be obtained. Note that the same tendency is observed when the dimension L1 of the terminal electrode in the base long side direction is performed for two patterns of 0.9 mm and 1.1 mm. Therefore, the dimension L2 of the terminal electrode in the short side direction of the base shows the solder stress. It can be seen that this is a particularly important component for mitigation.

  As described above, the present invention can improve the reliability of mounting and bonding of a package for electronic components and a circuit board, and can provide a package for electronic components that is easy to process and inexpensive.

  A first embodiment according to the present invention will be described with reference to the drawings by taking a surface-mounted crystal resonator as an example. FIG. 1 is a perspective view of a surface-mounted crystal resonator showing the first embodiment, FIG. 2 is a bottom view of FIG. 1, and FIG. 3 shows the surface-mounted crystal resonator showing the first embodiment. It is a partial sectional view mounted on a circuit board. The surface-mount type crystal resonator is bonded to a flat rectangular base 1 having a recess with an upper opening, a crystal diaphragm 3 which is a piezoelectric diaphragm housed in the base, and an opening of the base. It consists of a cap 2.

  As shown in FIG. 3, the base 1 is made of, for example, an alumina ceramic material, and is formed of a rectangular flat plate-shaped base base 1a and a frame 1b having a large central portion and an outer size substantially equal to the base base 1a. These layers are laminated and fired integrally. After the firing molding, the glass layer 11a is formed on the upper surface of the frame 1b by a technique such as baking. That is, the base 1 has a shape having a concave electronic element housing portion 10 in a cross section, and a circumferential glass layer 11a is formed on the bank portion 11 around the concave shape. Although the glass layer 11a is not formed, the base and the lid can be hermetically bonded. However, the bonding strength can be improved by forming the glass layer 11a. Castellations C1, C2, C3, and C4 are formed on the four corners of the outer periphery of the base. Of these, connection electrodes 121 and 131 are formed below the castellations C1 and C3, and the connection electrodes 121 and 131 are electrically connected to terminal electrodes 12 and 13, which will be described later.

  Further, as shown in FIG. 1, a pair of terminal electrodes 12, 13 are formed on the bottom surface of the base 1, and these terminal electrodes are connected electrodes 121, 131 (131 is not shown) and castellations C1, Via C3, the electrode pads 122 and 132 (132 is not shown) formed on the bottom surface inside the base are electrically extended. These terminal electrodes, connection electrodes, and electrode pads are formed by integrally firing a metallized material such as dungsten and molybdenum with the base, forming nickel plating on the metallized upper part, and forming gold plating on the upper part. Configured. Between the electrode pads 122 and 132, a rectangular crystal diaphragm 3 which is a piezoelectric diaphragm (electronic component element) is mounted. A pair of excitation electrodes are formed on the front and back surfaces of the quartz diaphragm 3. For example, the electrodes are in contact with the quartz diaphragm 3 in the order of chromium and gold, or in the order of chromium, gold and chromium, or in the order of chromium, silver and chromium. Is formed. The respective excitation electrodes are drawn out to the respective electrode pads 122 and 132 of the base, and the quartz diaphragm 3 on which the excitation electrodes are formed on the electrode pads 122 and 132 is, for example, a silicone-based conductive bonding material (not shown). )) And is cantilevered.

  The cap 2 hermetically sealing the base has a flat plate shape and is made of an alumina ceramic material or a ceramic glass material. For example, a lead-based, bismuth-based, or tin phosphate-based low-melting glass material 21 is formed on the bonding surface of the cap 2 as a sealing bonding material, and the glass material 21 is larger than the width of the base bank portion. And it forms in the cap 2 in the shape of a circumference in the state which protrudes in the electronic element accommodating part 10 in the base inner side. Thereby, the inner meniscus 21a can be created after heating as shown in FIG.

  In joining the base and the cap, the glass material formed on the cap is melted and hermetically sealed by heating at a predetermined temperature. In this hermetic sealing operation, in order to perform cap positioning and self-weight sealing, a pallet provided with storage portions in a matrix shape may be used and batch processing may be performed for a large number. For example, although not shown, a pallet in which concave storage portions having the same size as the base are formed in a matrix is prepared, and the cap 2 is first stored in each storage portion. The held base 1 is stored upside down in the storage section so that the opening contacts the cap 2. By heating to a predetermined temperature in this state, the glass material is melted, and a batch joining process for positioning the cap and sealing its own weight is performed. Note that a weighted weight may be mounted on the base 1 to promote the bonding between the base and the cap. Moreover, in the said embodiment, although the glass joining material is formed in both joining area | regions of a base and a cap, you may form only in one of a base or a cap. Thus, a surface-mount type crystal unit is completed. As shown in FIG. 3, the electrode pads 41 and 42 of the circuit board 4 made of a glass epoxy material are placed on the upper side of the electrode pads 41 and 42 via a conductive bonding material D such as solder. Be joined.

  Since the present invention is characterized by the shapes of the terminal electrodes 12 and 13, the details will be described below. As shown in FIG. 2, the pair of terminal electrodes 12 and 13 formed along the opposing sides of the bottom surface of the base 1 are not opposed to the regions 12a and 13a where the electrodes are formed facing each other. Regions 12b and 13b where only the terminal electrodes are not formed. These regions are arranged point-symmetrically with respect to the center point of the base 1, and the regions 12b and 13b that are not opposed to each other and are not formed with one terminal electrode are casters C2 that are diagonal portions of the base. Arranged at C4. The terminal electrodes 12 and 13 are formed only on the bottom surface of the base so as to be isolated from the sides of the bottom surface of the base 1 except for the castellations C1 and C3.

  With these configurations, the directionality of the terminal electrodes 12 and 13 is lost, and the mounting workability of the surface-mounted crystal resonator is improved. Further, the terminal electrode regions 12a and 13a can suppress the base 1 from being twisted three-dimensionally on the circuit board while increasing the bonding strength with the circuit board, thereby reducing the influence of warping of the circuit board 4 and the like. . Further, even if a stress is generated due to a difference in thermal expansion between the base 1 and the circuit board 4, the stress is released toward the corner regions 12 b and 13 b where one terminal electrode is not formed. The stress is relieved so that it rotates. For this reason, stress can be more efficiently relaxed without bias, and the occurrence of solder cracks and the like can be remarkably suppressed. In particular, as in the first embodiment of the present invention, in a package composed only of an insulating material in which the cap is hermetically sealed with a sealing bonding material such as glass with respect to the base, other than the input / output terminals of the crystal resonator This is extremely effective because it has a pair of terminal electrode structures (bipolar terminal electrode structure) that do not require a ground terminal or the like.

  Further, the terminal electrodes 12 and 13 of the first embodiment of the present invention are formed only on the bottom surface of the base so as to be isolated from the side of the bottom surface of the base 1 except for the castellations C1 and C3. This is because, in the ceramic green sheet before firing in which the base is arranged in a matrix through the subdivided grooves (break grooves), the metallized pattern for the terminal electrode is formed in a state where it is not in contact with the subdivided grooves. When the ceramic green sheets are divided by the subdivided grooves as the respective bases after firing the ceramic green sheet, the metallization pattern for the terminal electrode is formed over the subdivided grooves so as not to hinder the dividing workability.

  Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 5 is a bottom view of the surface-mount type crystal resonator showing the second embodiment. The same parts as those in the first embodiment are given the same numbers, and a part of the description is omitted.

  In the pair of terminal electrodes 12 and 13 of the second embodiment, as shown in FIGS. 5A and 5B, each terminal is directed toward the corner regions 12b and 13b where one terminal electrode is not formed. The shape of the electrodes 12 and 13 is made small for a while. Further, as shown in FIG. 5C, curvatures R1 and R2 are formed toward the corner regions 12b and 13b where one terminal electrode is not formed. In addition to these shapes, as in the first embodiment, the terminal electrodes 12 and 13 are not opposed to each other and regions 12a and 13a where the electrodes are formed. It has the area | regions 12b and 13b which only an electrode does not form. These regions are arranged point-symmetrically with respect to the center point of the base 1, and the regions 12b and 13b that are not opposed to each other and are not formed with one terminal electrode are casters C2 that are diagonal portions of the base. Arranged at C4. The terminal electrodes 12 and 13 are formed only on the bottom surface of the base so as to be isolated from the sides of the bottom surface of the base 1 except for the castellations C1 and C3. In these forms, the mutual stress suppression effect is enhanced, and the stress can be relaxed so as to be further rotated at the center point of the base 1. Further, by forming a curvature at the end of the terminal electrode as shown in FIG. 5C, stress concentration at this portion can be prevented.

  Next, a third embodiment of the present invention will be described with reference to FIG. 6 by taking a surface-mount type crystal resonator as an example. FIG. 6 is a bottom view of a surface-mount type crystal resonator showing a third embodiment. The same parts as those in the first embodiment are given the same numbers, and a part of the description is omitted.

  In the pair of terminal electrodes 12 and 13 of the third embodiment, as shown in FIG. 6, the region where the terminal electrodes are opposed to each other and the region where the electrodes are formed and the region where one terminal electrode is not formed is formed. The asymmetrical arrangement with respect to the center point of the base. That is, it has the area | regions 12a and 13a in which the terminal electrodes 12 and 13 oppose each other and the electrode is formed, and the area | region 13b in which only one terminal electrode does not form only the terminal electrode 13 does not oppose each other. . The terminal electrodes 12 and 13 are formed only on the bottom surface of the base so as to be isolated from the sides of the bottom surface of the base 1 except for the castellations C1 and C3. This configuration is effective when it is necessary to impart directionality to the terminals.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings by taking a surface-mounted crystal resonator as an example. FIG. 7 is a bottom view of the surface-mounted crystal resonator showing the fourth embodiment, and FIG. 8 is a partial cross-sectional view of the surface-mounted crystal resonator showing the fourth embodiment mounted on a circuit board. . The same parts as those in the first embodiment are given the same numbers, and a part of the description is omitted.

  In the fourth embodiment of the present invention, as shown in FIG. 7, a pair of terminal electrodes 12 and 13 are formed on the bottom surface of the base 1, and two bumps are provided at both upper ends of each terminal electrode. 14 and 14 are formed. These bumps are formed by laminating the same material metallization (dungsten, molybdenum, etc.) in the desired shape on top of the metallization of the terminal electrode, and firing the metallization material of these terminal electrode and bump integrally with the base Then, nickel plating is formed on the metallized upper part, and gold plating is formed on the upper part. In addition to these shapes, as in the first embodiment, the terminal electrodes 12 and 13 are not opposed to each other and regions 12a and 13a where the electrodes are formed. It has the area | regions 12b and 13b which only an electrode does not form. These regions are arranged point-symmetrically with respect to the center point of the base 1, and the regions 12b and 13b that are not opposed to each other and are not formed with one terminal electrode are casters C2 that are diagonal portions of the base. Arranged at C4. The terminal electrodes 12 and 13 are formed only on the bottom surface of the base so as to be isolated from the sides of the bottom surface of the base 1 except for the castellations C1 and C3.

  With these configurations, even if stress is generated due to a difference in thermal expansion between the base 1 and the circuit board 4, the stress can be alleviated by the step between the bump and the terminal electrode, and the conductive bonding material is provided in the gap portion lifted by the bump. As a result, the bonding strength with the circuit board can be further increased. In particular, as in the fourth embodiment of the present invention, since the two bumps 14 and 14 are formed at the upper end portions of each terminal electrode, respectively, when mounted on the circuit board of the surface mount type crystal resonator. No tilting occurs and more stable mounting is possible.

  In the above embodiment, a glass material is taken as an example of the sealing bonding material, but a resin or the like may be used. Further, laser sealing, beam sealing, seam sealing, etc. using a metal cap for the ceramic base and a brazing material such as a silver brazing material as the sealing bonding material can be applied. Furthermore, in the above-described embodiment, a surface-mount type crystal resonator is taken as an example, but the present invention can also be applied to other surface-mount type electronic component packages used for electronic devices such as crystal filters and crystal oscillators.

1 is a perspective view of a surface-mount type crystal resonator showing a first embodiment. FIG. The bottom view of FIG. FIG. 3 is a partial cross-sectional view in which the surface-mount type crystal resonator according to the first embodiment is mounted on a circuit board. The graph which shows the verification data of a solder endurance test. FIG. 6 is a bottom view of a surface-mount type crystal resonator showing a second embodiment. FIG. 6 is a bottom view of a surface-mount type crystal resonator showing a third embodiment. The bottom view of the surface mount-type crystal unit which shows 4th Embodiment. FIG. 6 is a partial cross-sectional view in which a surface-mount type crystal resonator according to a fourth embodiment is mounted on a circuit board.

Explanation of symbols

1 Base 2 Cap 3 Crystal diaphragm (piezoelectric diaphragm)
4 Circuit board

Claims (5)

An electronic component package comprising a planar rectangular base for holding an electronic component element and a cap for hermetically sealing the electronic component element,
A pair of terminal electrodes are formed along opposite sides of the bottom surface of the base,
The pair of terminal electrodes has a region where electrodes are formed facing each other and a region where one terminal electrode is not formed without facing each other,
A package for an electronic component, wherein the pair of terminal electrodes of the base and the circuit board are bonded together by a conductive bonding material. The pair of terminal electrodes are arranged symmetrically with respect to a center point of the base, and a region where one terminal electrode is not formed without being opposed to each other is arranged at a corner of the base. Package for electronic components as described. 3. The electronic component package according to claim 1, wherein the base is made of a ceramic material, the terminal electrodes are formed by metallization, and the circuit board is made of a glass epoxy substrate. The electronic component package according to claim 1, wherein a bump made of the same material metallization is formed on a part of the terminal electrode. The terminal electrode according to any one of claims 1 to 4, wherein the terminal electrode is formed with an extension dimension of 60% to 85% with respect to a base width dimension in a direction in which the terminal electrode extends. Package for electronic components.

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