JP7655110B2 - Base for electronic component packages, electronic component packages - Google Patents

Description

The present invention relates to a base for an electronic component package used in electronic devices, etc., and to an electronic component package.

Examples of electronic components that require hermetic sealing include piezoelectric vibration devices such as quartz crystal units, quartz crystal filters, and quartz crystal oscillators. In each of these products, a thin metal film electrode is formed on the surface of the quartz crystal plate, and the quartz crystal plate (specifically the thin metal film electrode) is hermetically sealed to protect the thin metal film electrode from the outside air.

In response to the demand for surface mounting of components, these piezoelectric vibration devices are increasingly being housed airtight in packages made of insulating materials such as ceramic. For example, Patent Document 1 discloses a configuration in which a package made of a ceramic material with a base (mounting substrate) having a mounting portion for a quartz vibration plate and a lid (cover) with an inverted concave cross section, with these hermetically sealed, is mounted on a circuit board and bonded via a conductive bonding material such as solder.

In this conventional piezoelectric vibration device, a terminal electrode is formed on the bottom surface of the base, and the terminal electrode extends from the bottom surface of the base to the side surface via castellations formed on the side surface of the base in order to check the connection state by creeping up of the solder (conductive bonding material).

For circuit boards mounting conventional piezoelectric vibration devices, so-called glass epoxy boards, in which mesh-like glass fibers are impregnated with epoxy resin, are widely used due to their ease of processing and cost benefits. Solder paste is applied to the top of the electrode pattern of the circuit board by a method such as screen printing. The terminal electrodes of the package of the piezoelectric vibration device are then placed on top of the electrode pattern of the circuit board in an overlapping state, and the solder paste is melted in a melting furnace (such as a heating furnace) to solder the piezoelectric vibration device onto the circuit board.

JP 2002-76813 A

However, due to the difference in thermal expansion coefficient between the package and the circuit board, stress is generated in the conductive bonding material such as solder that bonds the package to the circuit board, which can cause cracks.

In particular, when a combination configuration using a ceramic material such as alumina for the package and a glass epoxy board for the circuit board is used for applications in harsh environments such as in-vehicle applications, the package and circuit board are used in high and low temperature environments, and fatigue failure is likely to occur in conductive bonding materials such as solder due to the difference in thermal expansion coefficient between the package and the circuit board.

As such, the problem of cracks in conductive bonding materials such as solder, which is not a significant issue in normal temperature environments, becomes more pronounced in high and low temperature environments, and there is also the problem that peeling occurs at the cracked parts of the conductive bonding materials such as solder when the package and the circuit board are subjected to an impact.

The present invention has been made to solve the above problems, and aims to provide a base for an electronic component package and an electronic component package that prevents cracks in conductive bonding materials such as solder and improves the reliability of mounting and bonding between the electronic component package and the circuit board.

The present invention provides a base for an electronic component package in which at least four external terminals are formed on an insulating substrate that is rectangular in a plan view and holds an electronic component element, the external terminals having a main surface terminal portion formed on a bottom surface of the base and a side surface terminal portion formed on a side surface of the base, the main surface terminal portion and the side surface terminal portion are formed and connected to each other at the bottom surface and side surface of the base, the side surface terminal portion is formed at a position outside and inside both ends of the width of the main surface terminal portion, the side surface terminal portion is formed in division at both ends of the width of the main surface terminal portion, and the side surface terminal portion has different widths between the four corner sides of the insulating substrate and the side surface terminal portion on the central side .

The above configuration allows the main surface terminal section, which faces the mounting electrode of the circuit board and enhances the electrical connection function by providing a relatively large bonding area using a conductive bonding material such as solder, and the side terminal section, which is arranged in a direction perpendicular to the mounting electrode of the circuit board and generates an anchor effect using a conductive bonding material such as solder to enhance the mechanical bonding strength with the circuit board, to coexist in a single external terminal while sharing their respective specialized functions.

When forming one external terminal, the side terminal portion is formed at a position outside the width of the main surface terminal portion. This means that even if stress is generated in the conductive bonding material such as solder that bonds the base and the circuit board due to the difference in thermal expansion coefficient between them, the side terminal portion can receive the stress before it is transmitted directly to the main surface terminal portion, and the stress can be transmitted to the main surface terminal portion in a reduced state.

As a result, stress-induced cracks are less likely to occur in the conductive bonding material, such as solder, of the main surface terminal portion, and the electrical and mechanical connection function of the external terminal as a whole can be ensured in a more stable state. Furthermore, even if cracks occur in the conductive bonding material, such as solder, at the side terminal portion, the occurrence of cracks in the conductive bonding material, such as solder, at the main surface terminal portion can be delayed.

In particular, in a configuration in which four or more external terminals are formed on the bottom surface of the base, there is a concern that as electronic components become smaller, the area occupied by each external terminal in the bottom surface area of the base will become smaller. However, in the present invention, the mechanical joint strength can be increased by distinctively arranging the side terminal portions relative to the main surface terminal portions without unnecessarily increasing the area occupied by each external terminal in response to the miniaturization of electronic components.

In addition to the above configuration, the side terminal portion may be divided and formed at both ends of the width of the main surface terminal portion. In addition to the above-mentioned effects, this configuration can alleviate the stress in the area between the side terminal portions where no side terminal portion exists, even if stress occurs in the conductive bonding material such as solder that bonds the base and the circuit board due to the difference in thermal expansion coefficient between them. Also, the side terminal portions on the four corners of the insulating board may have different widths from the side terminal portion on the central portion. In addition to the above-mentioned effects, this configuration can change the balance of stress applied to the side terminal portion by combining at least two or more side terminal portions with different widths with the main surface terminal portion, thereby preventing localized concentration of stress.

In addition to the above configuration, the side terminals on the central side may be formed wider than the side terminals on the four corners . In this configuration, in addition to the above-mentioned advantageous effects, by forming the side terminals on the central side wider, stress can be easily alleviated, and even if a crack occurs in the conductive bonding material such as solder in the side terminals on the four corners, the side terminals on the central side can hold the solder more firmly, thereby suppressing the progression of the crack in the conductive bonding material such as solder of the main surface terminals.

In addition to the above configuration, the side terminals on the four corners may be formed in the four corner regions of the base. In this configuration, in addition to the above-mentioned advantageous effects, by forming the side terminals at the four corners which are the starting points of stress, the external terminals can be held more firmly and the progression of cracks in the conductive bonding material such as solder can be suppressed.

In addition to the above configuration, the main surface terminals may be formed along opposing long sides of the bottom surface of the base. In this configuration, in addition to the above-mentioned effects, by arranging the main surface terminals along the long side of the base, where the thermal expansion difference between the base and the circuit board is relatively large and the base is susceptible to the effects of stress, the side terminals are also arranged in the long side direction corresponding to the main surface terminals, so that the external terminals can be held more firmly and the progression of cracks in conductive bonding materials such as solder can be suppressed.

The present invention may also be an electronic component package characterized in that the base of the electronic component package described above has a lid that hermetically seals the electronic component element. This configuration makes it possible to provide an electronic component package that achieves the above-mentioned effects.

The present invention provides a base for an electronic component package and an electronic component package that prevents cracks in conductive bonding materials such as solder and improves the reliability of mounting and bonding between an electronic component package and a circuit board.

FIG. 2 is a bottom view of the surface mount type crystal resonator according to the embodiment of the present invention. 2 is a cross-sectional view of the surface mount type crystal unit of FIG. 1 mounted on a circuit board along line AA. 2 is a cross-sectional view of the surface mount type crystal unit of FIG. 1 mounted on a circuit board along line BB. FIG. 13 is a bottom view of a surface mount crystal resonator showing a modified example of an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. In each of the following examples, the present invention is applied to a surface-mount crystal resonator as an electronic component package.

As shown in Figures 1, 2, and 3, the surface mount type crystal unit according to the embodiment of the present invention comprises a crystal vibration plate 3, which is an electronic component element, a base 1 (insulating substrate) that has a recess with an open top and holds (stores) the crystal vibration plate 3, and a lid 2 that is joined to the opening of the base 1 to hermetically seal the crystal vibration plate 3 held by the base 1.

The base 1 is generally a rectangular parallelepiped, and is constructed by appropriately laminating a conductive material such as tungsten or molybdenum onto a ceramic insulating substrate such as alumina. As shown in FIG. 2, the base 1 has a storage section 10 that is concave in cross section, and a bank section 11 that is provided around the storage section 10 so as to surround it.

Specifically, the base 1 is composed of a ceramic base substrate 1a in the shape of a rectangular plate (rectangular when viewed from above) and a ceramic frame 1b with a large central hole and an outer size (outer size when viewed from above) approximately equal to that of the base substrate 1a, and the base substrate 1a, frame 1b, and part of the sealing member 11a are fired together. The upper surface of the bank portion 11 (frame 1b) is flat, and the sealing member 11a (sealing material, metal layer, etc.) is formed on the bank portion 11. The number of layers of the frame in the base 1 may be two or more depending on the package configuration.

In this embodiment, a sealing configuration using, for example, gold-tin brazing material is used as an example, so a configuration is shown in which a nickel-plated layer and a gold-plated layer are formed on the top surface of a metallized layer made of tungsten, molybdenum, or the like as the sealing member 11a. However, depending on the sealing configuration, a configuration in which a metal ring is formed on top of each of these layers, or a configuration in which glass is formed, may also be shown.

At the four corners (four corners) of the periphery (outer periphery in plan view) of the base 1, castellations C1 are formed on the four sides of the base 1 at these four corners, running from the bottom surface of the base to the top surface (upper surface). In addition, at the two specific side surfaces S1, S3 connected to the long sides H1, H3, which are the opposing specific sides of the bottom surface of the base 1, on the periphery (outer periphery in plan view) of the base 1, two castellations C2 are formed on the two specific side surfaces S1, S3, running from the bottom surface of the base to the top surface (upper surface).

The castellation C2 on the central side of the particular side of the base 1 is formed to be wider than the castellation C1 on the corner side of the particular side of the base 1, and is formed to be, for example, about 2 to 5 times wider.

The bottom surface of the base 1 (the back surface of the base 1) is rectangular in plan view, and four external terminals 12 are formed. Each external terminal 12 has a main surface terminal portion 13 formed on the bottom surface of the base 1, and side surface terminal portions 14, 15 formed inside a castellation on the side surface of the base 1.

The main surface terminal portions 13 are formed in a rectangular shape in plan view along the opposing long sides H1, H3 of the bottom surface of the base 1. The side surface terminal portions 14 are formed inside castellations C1 formed on the four corner side surfaces of the base 1. The side surface terminal portions 15 are formed inside castellations C2 formed on specific side surfaces S1, S3 of the base 1. Each main surface terminal portion 13 and each side surface terminal portion 14, and each main surface terminal portion 13 and each side surface terminal portion 15 are formed and connected to each other at the bottom surface and side surface of the base 1.

In this embodiment, as described above, the castellations C1 and C2 are formed with different width dimensions, so that the width dimension W1 of the side terminal portion 14 on the corner side and the width dimension W2 of the side terminal portion 15 on the central side formed here are also formed to be different, and in particular, the side terminal portion 15 on the central side is formed to be wider than the side terminal portion 14 on the corner side.

For example, if the width W1 of the side terminal portion 14 at the corner of the long side is 0.05 mm, the width W2 of the side terminal portion 15 at the center of the long side is formed to be about 0.1 mm, which is twice as wide, to 0.4 mm, which is eight times as wide. Note that the width W2 of the side terminal portion 15 at the center of the long side is desirably formed to be about one-sixth to one-third of the width W3 in the long side direction of the base 1, in order to suppress interference with other wiring on the base while improving the bonding strength with the circuit board 4 described below. Furthermore, forming the specific width W2 of the side terminal portion 15 to be 0.25 mm or more is desirable from the viewpoint of improving the bonding strength, as the solder fillet has a stronger structure.

The present invention is characterized by the positional relationship between each main surface terminal portion and each side surface terminal portion on the bottom surface of the base 1, and each side surface terminal portion 14, 15 is formed in a state where it is positioned outside the positions of both ends 131, 132 of each main surface terminal portion 13 along each long side (H1, H3). That is, in the two main surface terminal portions 13 formed along the long side H1, castellation C1 and side surface terminal portion 14 formed therein are formed at both ends of the long side H1 located outside the outer end 131 of each main surface terminal portion 13, and castellation C2 and side surface terminal portion 15 formed therein are formed at a position closer to the center of the long side H1 located inside the inner end 132 of each main surface terminal portion 13.

Similarly, in the two main surface terminal portions 13 formed along the long side H3, castellations C1 and side terminal portions 14 formed therein are formed at both ends of the long side H3, located outside the outer end 131 of each main surface terminal portion 13, and castellations C2 and side terminal portions 15 formed therein are formed at a position closer to the center of the long side H3, located inside the inner end 132 of each main surface terminal portion 13. As a result, the width along the long sides (H1, H3) of each main surface terminal portion 13 (both ends in the long side direction in this embodiment) is also divided into two side terminal portions 14, 15 formed at outer positions.

Each external terminal 12 extends to and is electrically connected to an electrode pad 16 formed on the inside bottom surface of the base 1 via a side terminal portion 14, a side terminal portion 15, or a via hole (not shown) formed on the castellation C1 or castellation C2.

These external terminals 12 (main surface terminal portion 13, side surface terminal portion 14, and side surface terminal portion 15) and electrode pads 16 are formed by firing a metallization material such as tungsten or molybdenum integrally with the base 1 to form a metallization, forming nickel plating on top of that, and then forming gold plating on top of that, just like the sealing member 11a.

The electrode pad 16 is mounted with a quartz crystal plate 3 (an electronic component element in the present invention). A pair of excitation electrodes and extraction electrodes (not shown) are formed on the front and back surfaces of the quartz crystal plate 3. The pair of excitation electrodes and extraction electrodes are formed, for example, in contact with the quartz crystal plate 3 (from above the quartz crystal plate 3) by laminating chromium and gold in that order, chromium, gold, chromium in that order, chromium, silver, chromium in that order, or chromium and silver in that order. Each of these electrodes (the pair of excitation electrodes and extraction electrodes) can be formed by a thin film formation method such as a vacuum deposition method or a sputtering method.

The extraction electrode of the quartz crystal plate 3 is conductively bonded to the electrode pad 16 by a conductive bonding material (not shown), and the quartz crystal plate 3 is held on the base 1. For example, conductive bonding materials such as conductive resin adhesive, metal bumps, metal plated bumps, and brazing material can be used to conductively bond the excitation electrode of the quartz crystal plate 3 to the electrode pad 16 of the base 1.

The lid 2 that hermetically seals the base 1 is made of a plate-shaped metal material with a sealing member 11a such as a gold-tin brazing material. The planar external shape of the lid 2 is approximately the same as or slightly smaller than the external shape of the base 1. The material of the lid 2 is not limited to metal, and it may be ceramic or glass.

The crystal plate 3 is stored in the storage section 10 of the base 1, covered with the lid 2, and hermetically sealed by a method such as fusion bonding in a heating furnace, completing a surface mount crystal oscillator (package for electronic components). Note that the method of hermetically sealing the base 1 and the lid 2 is not limited to soldering, and other methods such as welding and fusion bonding can be used depending on the various materials (base, lid, sealing material, etc.).

The completed quartz crystal unit is joined to the top of the electrode pattern 41 of the circuit board 4 made of glass epoxy material via a conductive bonding material D, such as solder, as shown in Figures 2 and 3.

In the above embodiment, two side terminals 14 and 15 are disposed at both ends of the main surface terminal 13 of each external terminal 12 in the width direction. However, the side terminals may be disposed at other ends than the ends, and may be divided into three or more in total.

Also, as shown in FIG. 4, a castellation C3 may be formed in each external terminal 12 such that the width dimension W4 is greater than the positions of both ends 131, 132 (both ends in the width direction) along each long side (H1, H3) of each main surface terminal portion 13, and a side terminal portion 17 may be formed along this castellation C3, thereby forming a side terminal portion 17 that is greater in width than both ends in the width direction of the main surface terminal portion 13 and that protrudes to a position outside in the width direction.

The above configuration can further reduce and prevent the adverse effects of cracks in conductive bonding materials such as solder caused by thermal shock stress, and can provide an inexpensive electronic component package base and electronic component package that improve the reliability of mounting and bonding on a circuit board.

In the above embodiment, the external terminals and castellations C2 (side terminal portions) are arranged on the long sides (H1, H3) as specific opposing sides, but they may be arranged on the short sides (H2, H4), or may be formed in the direction of both the long sides (H1, H3) and the short sides (H2, H4). Also, the castellations C1 at the four corners of the base may not have side terminal portions. In this case, multiple castellations C2 and side terminal portions may be formed on a specific side, either the long sides (H1, H3) or the short sides (H2, H4), or multiple castellations C2 and side terminal portions may be formed on both the long sides (H1, H3) and the short sides (H2, H4).

In the above embodiment, a surface mount type crystal resonator is used as an example, but the present invention can also be applied to other surface mount type electronic component packages used in electronic devices, such as crystal filters and crystal oscillators. In addition, although a ceramic material is disclosed as the insulating package (base), a glass material or crystal may also be used. Although metallization is disclosed as the metal film of the terminal electrodes, a plated material may also be used. Although the number of terminal electrodes has been described as four terminals, the present invention can also be applied to those with five or more terminals.

The present invention should not be interpreted as being limited in any way, since it can be implemented in various other ways without departing from its spirit or main characteristics. The scope of the present invention is indicated by the claims, and is not bound by the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention.

The present invention can be applied to packages for electronic components such as quartz crystal oscillators, and bases for electronic component packages.

1 Base 2 Lid 3 Quartz crystal plate (electronic component element)
4 Circuit board

Claims (4)

A base for an electronic component package, the base having at least four external terminals formed on an insulating substrate having a rectangular shape in a plan view and holding an electronic component element,
the external terminal has a main surface terminal portion formed on a bottom surface of the base and a side surface terminal portion formed on a side surface of the base,
the main surface terminal portion and the side surface terminal portion are formed to be connected to each other at the bottom surface and the side surface of the base,
the side terminal portions are formed at positions outside and inside both ends of the width of the main surface terminal portion ,
The side terminal portions are formed by dividing the main surface terminal portion into two portions, and the side terminal portions on the four corner sides of the insulating substrate have different widths from the side terminal portions on the central side.
A base for an electronic component package. 2. A base for an electronic component package according to claim 1,
The side terminals on the central side are formed wider than the side terminals on the four corners.
A base for an electronic component package. 3. A base for an electronic component package according to claim 2,
The side terminals on the four corners are formed in the four corner regions of the insulating substrate.
A base for an electronic component package. 4. An electronic component package comprising: a base for an electronic component package according to claim 1 ; and a lid for hermetically sealing said electronic component element.

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