JP2014057284A - Crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal device capable of suppressing short-circuiting due to contact between conductive adhesives in the crystal device on which at least two crystal elements are mounted.SOLUTION: A crystal device includes: a rectangular-shaped substrate 110; a first crystal element 120 which has a rectangular shape and which is arranged in the substrate 110 so that the long side follows the short side of the substrate 110; and a second crystal element 130 which has a rectangular shape and which is arranged in the substrate 110 adjacent to the first crystal element 120 so that the long side follows the short side of the substrate 110 and is parallel to the long side of the first crystal element 120.

Description

  The present invention relates to a crystal device used for electronic equipment and the like.

  A quartz crystal device uses a piezoelectric effect of a quartz crystal element to cause a thickness-shear vibration so that both surfaces of a quartz base plate are displaced from each other, thereby generating a specific frequency. By applying a drive voltage to the excitation electrodes attached to both sides of a flat plate-shaped quartz crystal element housed in a rectangular parallelepiped package having an internal space, vibration at a predetermined frequency can be taken out. (Patent Document 1). The crystal device is mounted on an integrated circuit unit in an electronic device including information devices such as a mobile phone and a personal computer. In particular, with the increase in functionality of electronic devices, electronic devices require a plurality of crystal devices that oscillate at different frequencies. Further, as electronic devices become smaller, a plurality of crystal devices are mounted. Quartz devices themselves are also becoming smaller.

  There has also been proposed a configuration in which a plurality of crystal elements are accommodated in one package and a plurality of signals are extracted from one package (Patent Document 2).

JP 2002-111435 A JP 2003-258589 A

  As represented by FIG. 3, the configuration of Patent Document 2 includes two quartz crystals in the package such that the long side of the rectangular substrate constituting the bottom surface of the package and the long side of the crystal element are aligned. A single-side holding structure in which elements are accommodated in parallel, one end in the long side direction of each crystal element is a fixed end joined to the upper surface of the substrate by a conductive adhesive, and the other end is a free end spaced from the upper surface of the substrate It has become. That is, along the short side of the rectangular substrate, the short sides on the fixed end sides of the two crystal elements are connected in series, and the electrodes provided on the fixed ends of the two crystal elements are arranged on the substrate in the package. The electrode is joined with a conductive adhesive.

  As the size of the crystal element is reduced, the length of the short side thereof becomes relatively shorter, and the application interval of the conductive adhesive is also reduced. Therefore, there is a risk of short circuit due to contact between adjacent conductive adhesives due to variations in the application position or diameter of the conductive adhesive.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a crystal device capable of suppressing a short circuit due to contact between conductive adhesives in a crystal device including at least two crystal elements. And

  In order to achieve the above object, an aspect of the quartz crystal device of the present invention includes a rectangular substrate, a first quartz crystal element arranged on the substrate having a rectangular shape and a long side thereof along the short side of the substrate, A second quartz crystal having a rectangular shape and disposed on the substrate adjacent to the first crystal element so that its long side is along the short side of the substrate and in parallel with the long side of the first crystal element. And an element.

  The crystal device according to one aspect of the present invention is mounted such that the short sides of the rectangular first crystal element and the second crystal element are adjacent along the long side of the rectangular substrate, Since the interval between the first crystal element and the second crystal element can be widened, a short circuit due to contact between the conductive adhesives can be suppressed.

It is a top view which shows the state which removed the cover body of the quartz crystal device in embodiment of this invention. It is sectional drawing of the AA line of FIG. It is a plane perspective view of the lower surface of the quartz crystal device in an embodiment of the present invention. 3 is a plan view showing a wiring pattern on the upper surface of a substrate 111. FIG. 4 is a plan view showing a wiring pattern of an intermediate wiring layer M. FIG. It is a figure which shows the simple equivalent circuit of a crystal device.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

  As shown in FIGS. 1 and 2, the crystal device according to the embodiment of the present invention accommodates two crystal elements of a first crystal element 120 and a second crystal element 130 in a package 110. In the present embodiment, an example in which two crystal elements are accommodated in a package will be described. However, the present invention can also be applied to a case where three or more crystal elements are accommodated in a package.

  The package 110 includes a rectangular substrate 111 and a frame 112 provided on the substrate 111 so as to surround it. The package 110 has a recess K surrounded by the upper surface of the substrate 111 and the inner surface of the frame 112, and the first crystal element 120 and the second crystal element 130 are accommodated and disposed in the recess K. ing. In the present embodiment, the rectangular first quartz crystal element 120 is arranged on the upper surface of the substrate 111 so that the long side is along the short side of the substrate 111 as shown in FIG. The second crystal element 130 is also arranged on the upper surface of the substrate 111 adjacent to the first crystal element 120 so that the long side is along the short side of the substrate 111 so that both long sides are in parallel. That is, the first crystal element 120 and the second crystal element 130 are arranged such that the short side of the first crystal element 120 and the short side of the second crystal element 130 extend along the long side of the substrate 111. Are arranged in parallel on the substrate 111.

  A lid 140 (not shown in FIG. 1) shown in FIG. 2 is placed on the frame 112 so as to close the opening of the recess K, thereby sealing the package 110.

  The lid 140 is made of, for example, an alloy containing at least one of iron, nickel, and cobalt. The lid 140 is for hermetically sealing the accommodation space K in a vacuum state or a state filled with nitrogen gas or the like. Specifically, a predetermined current is applied so that the sealing conductor pattern 112a of the frame body 112 and the sealing member 141 of the lid body 140 are welded in a predetermined atmosphere on the frame body 112 of the package 110. It is joined to the frame body 112 by applying and performing seam welding.

  The sealing member 141 is provided at a position of the lid body 130 facing the sealing conductor pattern provided on the upper surface of the frame body 112 of the package 110. The sealing member 141 is provided by, for example, silver solder or gold tin. In the case of gold tin, the thickness is 10 μm to 40 μm. For example, the component ratio is 78 to 82% for gold and 18 to 22% for tin. In the case of silver wax, the thickness is 10 to 20 μm. For example, the component ratio is 72 to 85% for silver and 15 to 28% for copper.

  The substrate 111 has a rectangular shape having a long side and a short side, and functions as a support member for supporting the first crystal element 120 and the second crystal element 130 mounted in the recess K. On the upper surface of the substrate 111, a pair of first electrode pads P1, P2 for bonding to the first crystal element 120 and another pair of second electrode pads P3, P4 for bonding to the second crystal element 130 are provided. Are provided side by side. As shown in FIG. 3, four external connection electrode terminals D1, D2, D3, and D4 are provided at the four corners of the lower surface of the substrate 111, and ground terminals G1 and G2 are further provided. . The ground terminal G1 is provided between the two external connection electrode terminals D1 and D2 at both ends of the long side of the substrate 111, and the ground terminal G2 is 2 at both ends of the other long side of the substrate 111. Two external connection electrode terminals D3 and D4 are provided. Thus, the ground terminal G1 is provided between the two external connection electrode terminals D1 and D2 at both ends of the long side of the substrate 111, and the ground terminal G2 is the both ends of the other long side of the substrate 111. Noise is superimposed on the oscillation frequencies of the first crystal element 121 and the second crystal element output from the external connection electrode terminal by being provided between the two external connection electrode terminals D3 and D4. Can be reduced.

  The substrate 111 is made of an insulating layer made of a ceramic material such as alumina ceramic or glass-ceramic, and has a multilayer structure in which a plurality of insulating layers are stacked. On the surface and inside of the substrate 111, the first electrode pads P1, P2 and the second electrode pads P3, P4 on the upper surface of the substrate 111 and the external connection electrode terminals D1, D2, D3, D4 on the lower surface are electrically connected. Wiring patterns and via conductors to be connected are provided. The wiring pattern of the substrate 111 will be described later.

  The frame body 112 is for forming the recess K on the substrate 111. The frame body 112 is made of a ceramic material such as alumina ceramics or glass-ceramics, and is formed integrally with the substrate 111.

  The first crystal element 120 and the second crystal element 130 have a function of oscillating a reference signal of a predetermined frequency of an electronic device or the like by stable mechanical vibration and a piezoelectric effect. In FIG. 3, a cross-sectional view of the first crystal element 120 is shown as an example, but the second crystal element 130 has the same structure as the first crystal element 120. Hereinafter, the structure of the first crystal element 120 will be described, and reference numerals of corresponding elements of the second crystal element 130 are given in parentheses of reference numerals of the respective elements. In addition, when the oscillation frequency of the 1st crystal element 120 and the 2nd crystal element 130 differs, the shape and size of a crystal element are each determined according to other design elements, such as the oscillation frequency and crystal impedance.

  The first crystal element 120 (130) includes an excitation electrode 122 (132), a connection electrode 123 (133), and an extraction electrode 124 (134) on the upper and lower surfaces of a rectangular crystal base plate 121 (131), respectively. For example, by a vapor deposition technique or a sputtering technique. The vibration region of the crystal element is a region where the excitation electrode attached to the upper surface of the crystal element and the excitation electrode attached to the lower surface face each other.

  The excitation electrode 122 (132), the connection electrode 123 (133), and the extraction electrode 124 (134) are formed by forming a first metal film on both main surfaces of the quartz base plate 121 (131), A second metal film is formed so as to be laminated on the upper surface of the metal film. The first metal film is made of, for example, chromium or titanium, and the second metal film is made of, for example, gold. Further, in order to increase the bonding force between the first metal film and the second metal film, for example, nickel may be formed between the first metal film and the second metal film.

  The extraction electrode 124 (134) is provided so as to extend from the excitation electrode 122 (132) to the short side along the long side of the crystal base plate 121 (131), and one end of the extraction electrode 124 (134). Is connected to the excitation electrode 122 (132), and the other end is connected to the connection electrode 123 (133). The connection electrode 123 (133) is connected to the extraction electrode 124 (134), and preferably, the upper surface side and the lower surface side are electrically connected to both surfaces of both corners on one end side of the crystal base plate 121 (131). Two connection electrodes 123 (133) and the first electrode pads P1, P2 (second electrode pads P3, P4) are electrically connected by the conductive adhesive DS. An extraction electrode 124 (134) extending from the excitation electrode 122 (132) on the upper surface side is connected to one connection electrode 123 (133), and an extraction electrode 124 (extending from the excitation electrode 122 (132) on the lower surface side is provided. 134) is connected to the other connection electrode 123 (133) on the lower surface side.

  The crystal element 120 (130) to which the excitation electrode 122 (132) is attached is mounted on the package 110. The conductive adhesive DS is applied by a dispenser, for example, so as to rise to a predetermined height on the pair of electrode pads P1, P2. The conductive adhesive DS is transported to the top of the conductive adhesive DS coated with the crystal element 120 (130), and the connection electrode 123 (133) provided on the fixed end side of the crystal element 120 (130). It is mounted on the top of the conductive adhesive DS so as to come into contact. Then, the crystal element 120 (130) is electrically cured by the conductive adhesive DS, so that the crystal element 120 (130) is electrically connected to the first electrode pads P1 and P2 (second electrode pads P3 and P4). Connected and mounted in the package 110.

  The conductive adhesive DS contains conductive powder as a conductive filler in a binder such as silicon resin, and the conductive powder includes aluminum, molybdenum, tungsten, platinum, palladium, silver, titanium, One containing either nickel or nickel iron, or a combination thereof is used. Moreover, as a binder, a silicon resin, an epoxy resin, a polyimide resin, or a bismaleimide resin is used, for example.

  In the first crystal element 120 (130), a fixed end in which one end of the crystal element 120 (130) connected to the first electrode pads P1 and P2 (second electrode pads P3 and P4) is connected to the upper surface of the substrate 111. The first crystal element 120 (130) is fixed on the substrate 111 with a one-side holding structure with the other end being a free end spaced from the upper surface of the substrate 111. In the first crystal element 120 (130), an alternating voltage from the outside is applied to the crystal element plate 121 (131) from the connection electrode 123 (133) via the extraction electrode 124 (124) and the excitation electrode 122 (132). When applied, the quartz base plate 121 (131) excites in a predetermined vibration mode and frequency.

  The quartz base plate 121 (131) is cut from an artificial crystalline lens at a predetermined cut angle (for example, AT cut), is a substantially flat plate shape that has been subjected to external processing, and has a planar shape such as a rectangular shape, and is flat over the entire surface. Yes, the thickness in the vertical direction is uniform. Further, so-called bevel processing may be performed to make the peripheral region around the center region of the quartz base plate 121 thinner. For example, when the crystal base plate 121 (131) is rectangular, the central portion of the crystal base plate 121 is an intersection of the diagonal lines, and when it is a circle or an ellipse, it is the center point. As a dimension example, the dimension of one side of the quartz base plate 121 (131) is, for example, 0.8 to 2.0 mm. In that case, the dimension of one side of the excitation electrode 122 (in the case of a rectangle) is 0.6 to 1.5 mm.

  A method for beveling a quartz element will be described. A polishing material provided with media and abrasive grains of a predetermined particle size, and a quartz base plate formed to a predetermined size are prepared. The prepared abrasive and quartz base plate are placed in the cylindrical body, and the open end of the cylindrical body is closed with a cover. A beveling process is performed by polishing a quartz base plate that rotates a cylindrical body in which an abrasive and a quartz base plate are placed with the central axis of the cylindrical body as a rotation axis.

  The shape of the pair of excitation electrodes 122 (132) attached to both surfaces of the quartz base plate 121 (131) is a quadrangle, a circle, an ellipse, or the like. The vibration (thickness shear vibration) of the crystal element 120 (130) is generated such that the displacement gradually increases from the outer peripheral side of the excitation electrode 122 (132) toward the center.

  The first crystal element 120 and the second crystal element 130 in the present embodiment are arranged on the substrate 111 such that the long sides thereof are along the short sides of the substrate 111 and the long sides are parallel to each other. That is, the first crystal element 120 and the second crystal element 130 are arranged such that the short side of the first crystal element 120 and the short side of the second crystal element 130 extend along the long side of the substrate 111, respectively. Are arranged in parallel on the substrate 111, so that the distance between the first crystal element 120 and the second crystal element 130 can be widened as compared with the case where the first crystal element 120 and the second crystal element 130 are arranged along the short side of the substrate 111. it can. That is, the interval between the first electrode pad P2 that is connected to the first crystal element 120 adjacent to each other and the second electrode pad P3 that is connected to the second crystal element 130 can be widened. Suppressing the possibility of contact of the conductive adhesive DS that may be caused by variations in the application position or diameter of the conductive adhesive DS applied to the surface, and short-circuiting between the first electrode pad P2 and the second electrode pad P3 Can be prevented.

  Next, the wiring of the substrate 111 will be described. An intermediate wiring layer M shown in FIG. 4 is provided between the upper surface and the lower surface of the substrate 111. FIG. 5 shows wiring on the upper surface of the substrate 111, and FIG. 6 shows wiring on the intermediate wiring layer M. At least one of the first electrode pads P1 and P2 and the second electrode pads P3 and P4 on the upper surface of the substrate 111 is connected to the wiring of the intermediate wiring layer M via the via conductor, and the wiring of the intermediate wiring layer M And electrically connected to the external connection electrode terminal on the lower surface of the wiring board 111.

  As described above, the first wiring 113 drawn from one of the pair of first electrode pads and the second wiring 114 drawn from one of the pair of first electrode pads are connected via different layers. One of the pair of second electrode pads and the third wiring 115 connected to the two external connection electrode terminals D1 and D3 in a diagonal relationship and drawn from one of the pair of second electrode pads. The fourth wiring 116 led out from is connected to another two external connection electrode terminals D2 and D4 having a diagonal relationship through different layers. Thus, the first wiring 113, the second wiring 114, the third wiring 115, the fourth wiring 116, the first electrode pads P1, P2, and the second electrode pads P3, P4 are connected to the conductive adhesive DS. It is possible to reduce a short circuit due to contact through the.

  For example, as shown in FIGS. 5 and 6, one first electrode pad P1 connected to the first crystal element 120 is provided at a corner portion through a first wiring 113 extending to the nearest corner portion. The external connection electrode terminal D1 on the lower surface of the substrate 111 is connected via the one side electrode T1. The other first electrode pad P2 connected to the first crystal element 120 is connected to the second wiring 114 of the intermediate wiring layer M through the first via conductor V1. The second wiring 114 extends in the intermediate wiring layer M to a corner where the external connection electrode terminal D3 is provided, and is connected to the external connection electrode terminal D3 via a third side electrode T3 provided at the corner.

  One second electrode pad P3 connected to the second crystal element 130 is connected to the third wiring 115 of the intermediate wiring layer M through the second via conductor V2. The third wiring 115 extends in the intermediate wiring layer M to a corner where the external connection electrode terminal D4 is provided, and is connected to the external connection electrode terminal D4 via a fourth side electrode T4 provided at the corner. The other second electrode pad P4 is also connected to the external connection electrode terminal D2 on the lower surface of the substrate 111 through the fourth wiring 116 extending to the nearest corner portion from the second side electrode T2 provided at the corner portion. In FIG. 6, a portion overlapping with the frame body 112 is drawn through.

  Therefore, the first crystal element 120 is electrically connected to the two external connection electrode terminals D1 and D3 having a diagonal relationship, and the second crystal element 130 is connected to two other external terminals having the diagonal relationship. It is electrically connected to the connection electrode terminals D2, D4.

  In this way, the first crystal element 120 and the second crystal element 130 can be electrically connected to the four external connection electrode terminals through the shortest path. Therefore, it is possible to reduce the load capacitance applied to the first crystal element 120 and the second crystal element 130. In addition, two external connection electrode terminals in a diagonal relationship are electrically connected to the first crystal element 120 via a pair of first electrode pads P1 and P2, and two other external terminals in a diagonal relationship are connected. Since the connecting electrode terminal is electrically connected to the second crystal element 130 via the pair of second electrode pads P3 and P4, the crystal device can stably operate even if the orientation is changed by 180 degrees. The oscillation frequency of the first crystal element 120 and the second crystal element 130 can be output. Preferably, the wiring length of the first wiring 113 drawn from one first electrode pad P1 of the first crystal element 120 and the second wiring drawn from the other first electrode pad P2 of the first crystal element 120 are preferable. The length obtained by adding the wiring length of 114 is the wiring length of the third wiring 115 drawn from one second electrode pad P3 of the second crystal element 130 and the other second electrode pad of the second crystal element 130. The length obtained by adding the wiring length of the fourth wiring 116 drawn from P4 is substantially equal to the length. Here, the substantially equal length is a length obtained by adding the wiring length of the first wiring 113 and the wiring length of the second wiring 114, and a length adding the wiring length of the third wiring 115 and the wiring length of the fourth wiring 116. Including a difference of 0 to 200 μm. As for the length of the wiring, the length of a straight line passing through the center of each wiring is measured.

The wiring length of the third wiring 115 drawn from one second electrode pad P3 of the second crystal element 130 and the wiring of the fourth wiring 116 drawn from the other second electrode pad P4 of the second crystal element 130. Since the length obtained by adding the length and the substantially equal length make the generated load capacitances equal, and the load capacitances applied to the first crystal element 120 and the second crystal element 130 are also uniform, the first Thus, it is possible to stably output the oscillation frequencies of the crystal element 120 and the second crystal element 130. As shown in FIG. 6, the equivalent circuit of the crystal element includes an equivalent series capacitance C <b> 1 formed by a portion that actually vibrates among the excitation electrodes (a portion opposite to the pair of excitation electrodes), and an equivalent inductance L. And an equivalent series resistance R1 are connected in series, and an equivalent parallel capacitance C0 is connected in parallel to the equivalent series resistance R, equivalent series capacitance C1, and equivalent inductance L. An equivalent circuit of the crystal device is formed in a state where a load capacitor CL mainly composed of an oscillation circuit is added in parallel to the equivalent circuit of the crystal element 120. In many oscillation circuits, the load capacitance CL is defined as Ca and Cb, which are two capacitors connected in parallel to a crystal element.
CL = (Ca · Cb) / (Ca + Cb) + Cs
Where Cs is the stray capacitance of the wiring or component. The oscillation frequency of the crystal device is generally determined in relation to the load capacitance CL of the oscillation circuit of the crystal device, and the load capacitance CL varies depending on the stray capacitance caused by the wiring pattern of the substrate 111 and the like. In a crystal device that accommodates two crystal elements, the first crystal element 120 and the second crystal element 130, the length of the wiring connected to the first crystal element 120 and the length of the wiring connected to the second crystal element 130 are If they are different, the fluctuation amount of the oscillation frequency due to the stray capacitance of the wiring pattern in both crystal elements will be different. Therefore, by making the wiring lengths of the wiring connected to the first crystal element 120 and the wiring connected to the second crystal element 130 equal, the stray capacitances of the first crystal element 120 and the second crystal element 130 are equal. Thus, the difference in the fluctuation amount of the oscillation frequency of both crystal elements can be suppressed.

  Further, the intermediate wiring layer M is provided with a fifth wiring 118 connected to the ground electrode terminals G1 and G2 on the lower surface of the substrate 111 via the third via conductor V3 and the fourth via conductor V4. The fifth wiring 118 is electrically connected to the lid 140 via a fifth via conductor V5 that penetrates part of the frame 112, and connects the lid 140 to the ground electrode terminals G1 and G2. By connecting the lid 140 to the ground, the shielding property in the recess K by the lid 140 is improved.

  The crystal device according to the present embodiment accommodates a plurality of crystal elements in a package, and each crystal element is arranged in parallel so that the short side of each crystal element is along the long side of the substrate. , I.e., the distance between electrode pads adjacent to each other and connected to different crystal elements can be increased, thereby reducing the possibility of contact between conductive adhesives applied to adjacent electrode pads, thereby A short circuit can be prevented.

  Further, the lengths of the wirings connecting the electrode pads connected to the connection electrodes 123 of the plurality of crystal elements housed in the package and the external connection terminals provided on the substrate 111 are substantially equal for each crystal element. By setting the length, the stray capacitance in each of the plurality of crystal elements becomes equal, and a difference in fluctuation amount of the oscillation frequency of the plurality of crystal elements can be suppressed.

  The present invention is not limited to the above-described embodiment, and there are design changes within a range that does not depart from the gist including various modifications and corrections that can be conceived by those having ordinary knowledge in the field of the present invention. Of course, it is included in the present invention. For example, although the case where the frame body 112 is integrally formed of a ceramic material in the same manner as the substrate 111 has been described, the frame body 112 may be made of metal. In this case, the frame is joined to the conductor film of the substrate via a brazing material such as silver-copper.

110: Package 111: Substrate 112: Frame 112a: Sealing conductor pattern 113: First wiring 114: Second wiring 115: Third wiring 116: Fourth wiring 118: Fifth wiring 120, 130: Crystal element 121, 131: Crystal base plate 122, 132: Excitation electrode 123, 133: Connection electrode 124, 134: Extraction electrode 140: Cover body 141: Sealing member D1, D2, D3, D4: External connection electrode terminal G1, G2 : Ground terminal P1, P2: First electrode pad P3, P4: Second electrode pad

Claims (5)

A rectangular substrate;
A first crystal element disposed on the substrate so that the long side is along the short side of the substrate, having a rectangular shape;
It has a rectangular shape and is disposed on the substrate adjacent to the first crystal element so that its long side is along the short side of the substrate and in parallel with the long side of the first crystal element. A crystal device comprising: a second crystal element. In claim 1,
A pair of first electrode pads provided along the long side of the upper surface of the substrate;
A pair of second electrode pads provided adjacent to the pair of first electrode pads;
Four external connection electrode terminals provided at the four corners of the lower surface of the substrate,
Of the four external connection electrode terminals, two external connection electrode terminals in a diagonal relationship are electrically connected to the first crystal element through the pair of first electrode pads, and are in a diagonal relationship. The other two external connection electrode terminals are electrically connected to the second crystal element through the pair of second electrode pads. In claim 2,
The substrate has a multi-layer structure, and a first wiring drawn from one of the pair of first electrode pads and a second wiring drawn from one of the pair of first electrode pads are: The two external connection electrode terminals in the diagonal relationship are connected through different layers, and the third wiring drawn out from one of the pair of second electrode pads and the pair of second electrode pads A fourth wiring led out from one of the electrodes is connected to two other external connection electrode terminals having the diagonal relationship through different layers. In claim 3,
The length obtained by adding the wiring length of the first wiring and the wiring length of the second wiring is substantially equal to the length obtained by adding the wiring length of the third wiring and the wiring length of the fourth wiring. Crystal device characterized by. In any of claims 2 to 4,
A crystal device, wherein a ground electrode terminal is provided between two external connection electrode terminals at both ends of the long side of the substrate.

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