JP2024058329A - Solid-state imaging device package manufacturing method - Google Patents

Abstract

[Problem] To provide a highly reliable solid-state imaging device package. [Solution] A method for manufacturing a solid-state imaging device package according to one aspect of the present invention is a method for manufacturing a solid-state imaging device package including a solid-state imaging device having a functional part for capturing images and a margin part surrounding the functional part, a frame-shaped frame disposed in the margin part, and a transparent substrate fixed to the frame so as to cover the functional part, the method including the steps of forming the frame having a plurality of resin layers on one of the solid-state imaging device and the transparent substrate by repeating two or more times the formation of a resin layer by laminating a photosensitive resin composition and exposing the resin layer, and bonding the other of the solid-state imaging device and the transparent substrate to the frame, and in the step of forming the frame, the amount of exposure immediately after laminating at least one of the plurality of resin layers is made different from the amount of exposure immediately after laminating the other of the plurality of resin layers. [Selected Figure] Figure 3

Description

The present invention relates to a method for manufacturing a solid-state imaging device package.

A solid-state imaging element package is used in which a frame that surrounds the solid-state imaging element is attached to a substrate on which the solid-state imaging element is mounted, and the opening of the frame is covered with a glass plate or the like (see, for example, Patent Document 1). The frame prevents degradation of image quality, such as ghosting, caused by light entering the solid-state imaging element from the side.

JP 2004-296453 A

The demand for smaller, more precise solid-state imaging device packages, such as those with a Glass on Chip (GoC) structure in which a cover glass is attached directly to the imaging device, is increasing day by day. However, the smaller frame reduces the bonding area, which can cause the frame to peel off easily from the solid-state imaging device and the substrate. For this reason, the present invention aims to provide a method for manufacturing a highly reliable solid-state imaging device package.

A method for manufacturing a solid-state imaging device package according to one aspect of the present invention is a method for manufacturing a solid-state imaging device package including a solid-state imaging device having a functional part for capturing images and a margin part surrounding the functional part, a frame-shaped frame disposed in the margin part, and a transparent substrate fixed to the frame so as to cover the functional part, the method including the steps of forming the frame having a plurality of resin layers on one of the solid-state imaging device and the transparent substrate by repeating lamination of a photosensitive resin composition and formation of a resin layer by exposure to light at least two times, and bonding the other of the solid-state imaging device and the transparent substrate to the frame, and in the step of forming the frame, the exposure amount immediately after lamination of at least one of the plurality of resin layers is made different from the exposure amount immediately after lamination of the other of the plurality of resin layers.

In the above-mentioned method for manufacturing a solid-state imaging device package, in the step of forming the frame, the amount of exposure immediately after laminating the last resin layer of the plurality of resin layers may be made different from the amount of exposure immediately after laminating the other resin layers of the plurality of resin layers.

In the above-mentioned method for manufacturing a solid-state imaging device package, in the step of forming the frame, the amount of exposure immediately after laminating the last resin layer may be smaller than the amount of exposure immediately after laminating the other resin layers.

The amount of exposure immediately after lamination of the final resin layer may be an amount of exposure that keeps the photosensitive resin composition in a B-stage state.

In the above-mentioned method for manufacturing a solid-state imaging device package, the amount of exposure immediately after laminating at least one of the plurality of resin layers may be an amount of exposure that keeps the photosensitive resin composition in a B-stage state.

The solid-state imaging device package manufacturing method according to the present invention can provide a highly reliable solid-state imaging device package.

1 is a cross-sectional view of a solid-state imaging device package manufactured by a method for manufacturing a solid-state imaging device package according to an embodiment of the present invention. 4 is a flowchart showing the steps of a method for manufacturing a solid-state imaging device package according to an embodiment of the present invention. 3 is a flowchart showing a detailed procedure of the frame formation step in FIG. 2 .

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a solid-state imaging device package 1 according to one embodiment of the present invention.

The solid-state imaging device package 1 includes a mounting substrate 10, a solid-state imaging device 20 mounted on the mounting substrate 10, a frame 30 arranged on the solid-state imaging device 20, a transparent substrate 40 fixed to the frame 30 so as to cover the solid-state imaging device 20 with a gap therebetween, and a sealant 50 that seals the outside of the frame 30 and the transparent substrate 40 on the mounting substrate 10.

The mounting board 10 is a structural member that supports the solid-state imaging element 20. For this reason, the mounting board 10 is formed from a material that has sufficient rigidity. The mounting board 10 may be a simple support that does not have any components that are electrically incorporated into a circuit, but is preferably a circuit board on which a circuit is formed that supplies power to the solid-state imaging element 20 and extracts a signal from the solid-state imaging element 20. In this embodiment, the mounting board 10 is a circuit board on which a circuit including a terminal 11 for electrically connecting to the solid-state imaging element 20 is formed.

Examples of the mounting substrate 10 include organic materials such as polyimide, polyester, ceramic, epoxy, bismaleimide triazine resin, and phenolic resin; structures in which paper or nonwoven glass fabric is impregnated with the organic materials and then heated to harden; ceramics such as alumina, aluminum nitride, beryllium oxide, and silicon nitride; and metal substrates. Among these, preferred are glass epoxy substrates, ceramic substrates, and bismaleimide triazine resin substrates. Circuits having metal wiring patterns and metal bumps can be formed on the surface or inside of these insulating substrates.

The solid-state imaging element 20 has a functional section 21 that captures images, a margin section 22 that surrounds the functional section 21, and a connection section 23 that is provided further outside the margin section 22. The solid-state imaging element 20 can be mounted on the side of the mounting substrate 10 that faces the transparent substrate 40. The functional section 21 can be formed as a two-dimensional imaging element structure such as a CMOS image sensor. The margin section 22 is an area in which the frame 30 is fixed, and no components that should be exposed are provided (buried wiring, etc. may be provided). The connection section 23 is an area in which a terminal 231 is provided for electrically connecting the solid-state imaging element 20 to the mounting substrate 10, etc. In this embodiment, the solid-state imaging element 20 and the mounting substrate 10 are electrically connected by a wire 232.

The frame 30, together with the transparent substrate 40, forms an enclosed space on the solid-state imaging element 20 that encloses the functional section 21. The frame 30 is formed from a photosensitive resin composition mainly composed of a photocurable resin. The frame 30 is formed by laminating a plurality of resin layers 31 to 36. The frame 30 may have unevenness on its inner circumferential surface due to the difference in planar shape of the plurality of resin layers 31 to 36. By forming unevenness on the inner circumferential surface of the frame 30, light incident on the inner circumferential surface of the frame 30 can be scattered, and light reflected by the frame 30 can be prevented from entering the functional section 21. The number of the resin layers 31 to 36 may be 2 or more, but is preferably 3 to 100, and more preferably 5 to 50.

In order to accurately determine the relative position and orientation of the frame 30 with respect to the solid-state imaging element 20 and the transparent substrate 40, it is preferable that the frame 30 is directly bonded to both the solid-state imaging element 20 and the transparent substrate 40 without using an adhesive or the like. In addition, the frame 30 is preferably formed from a resin composition containing a pigment or a light diffusing material so as to prevent light from entering the functional part 21 from the side. Furthermore, in order to prevent light reflected from the inner circumferential surface from entering the functional part 21, the frame 30 is preferably formed in an inverse tapered shape in which the diameter of the inner circumferential surface decreases toward the transparent substrate 40 side, and may be shaped so that the diameter reduction rate of the inner circumferential surface is smaller on the transparent substrate 40 side, for example, in a stepped or dome shape.

The transparent substrate 40 allows light to enter the solid-state imaging element 20. The transparent substrate 40 can be made of transparent ceramics such as glass or sapphire, or transparent plastics such as acrylic resin or polycarbonate, with transparent ceramics being preferred from the viewpoint of reliability. From the viewpoint of versatility, it is preferable to use glass. The type of glass is not particularly limited, but examples include quartz glass, borosilicate glass, and non-alkali glass. The transparent substrate 40 may be bonded to the frame 30 with an adhesive, but it is preferable that the material of the frame 30 is directly laminated onto one side of the transparent substrate 40.

The sealing material 50 seals the outside of the solid-state imaging element 20, frame 30, and transparent substrate 40 on the mounting substrate 10, thereby preventing the frame 30 and transparent substrate 40 from being peeled off from the solid-state imaging element 20 by an external object. The sealing material 50 also protects the wires 232 and ensures electrical connection between the mounting substrate 10 and the solid-state imaging element 20.

As the sealing material 50, for example, a thermosetting resin such as an epoxy resin, an acrylic resin, or a silicone resin is preferable, and an epoxy resin is particularly preferable from the viewpoint of toughness and heat resistance. Moreover, the sealing material 50 is preferably formed from a resin composition containing a light diffusing material or a light absorbing material so as to prevent unintended noise light from being incident on the functional part 21. Moreover, the sealing material 50 may contain a filler such as silica so as to have thixotropy before curing in order to facilitate formation.

The above solid-state imaging element package 1 can be manufactured by a method for manufacturing a solid-state imaging element package according to one embodiment of the present invention shown in Figure 2. The method for manufacturing a solid-state imaging element package according to this embodiment includes a step of mounting a solid-state imaging element 20 on a transparent substrate 40 (step S1: element mounting step), a step of forming a frame 30 on a transparent substrate 40 using a photosensitive resin composition (step S2: frame forming step), and a step of adhering the solid-state imaging element 20 mounted on the mounting substrate 10 to the frame 30 (step S3: element adhering step).

In the element mounting process of step S1, the solid-state imaging element 20 is mounted on the mounting substrate 10. The method for mounting the solid-state imaging element 20 is not particularly limited, and well-known mounting techniques such as wire bonding and flip chip bonding can be used.

In the frame formation process of step S2, the formation of resin layers 31-36 by laminating a photosensitive resin composition on a transparent substrate 40 and exposing the resin layers 31-36 is repeated two or more times to form a frame 30 having multiple resin layers 31-36. Specifically, as shown in FIG. 3, the frame formation process includes a process of initially setting a loop parameter n that manages the layer number (step S21: loop parameter setting process), a process of acquiring the formation conditions for the n-th resin layer 31-36 (step S22: condition acquisition process), a process of laminating the photosensitive resin composition (step S23: laminating process), a process of exposing the laminated photosensitive resin composition (step S24: exposure process), a process of confirming the number of formed resin layers 31-36 (step S25: layer number confirmation process), and a process of adding the loop parameter n (step S26: loop parameter addition process).

In the loop parameter setting process of step S21, the loop parameter n, which indicates the number of the resin layers 31 to 36 to be formed, is set to an initial value of 1.

In the condition acquisition process of step S22, the formation conditions of the resin layers 31-36 indicated by the loop parameter n are acquired. Specific formation conditions include the planar shape, thickness, exposure time, etc. of the nth resin layer 31-36. Among the formation conditions, the exposure amount is set to a different value for each of the resin layers 31-36. The exposure amount in the exposure process immediately after lamination of at least one of the resin layers 31-36 is set to a different value from the exposure amount in the exposure process immediately after lamination of the other resin layers of the resin layers 31-36.

In the lamination process of step S23, the photosensitive resin composition is laminated according to the conditions acquired in the condition acquisition process. Specific means for laminating the photosensitive resin composition include an inkjet 3D printer, a stereolithography 3D printer, a screen printer, etc.

In the exposure step of step S24, the photosensitive resin composition laminated in the lamination step is exposed according to the conditions acquired in the condition acquisition step. The lower limit of the exposure amount in each exposure step is the minimum amount that can reduce the fluidity of the photosensitive resin composition laminated in the immediately preceding lamination step and provide a retention form that can support the photosensitive resin composition laminated in the next lamination step. On the other hand, the upper limit of the exposure amount in each exposure step is the maximum amount that keeps the photosensitive resin composition laminated in the immediately preceding lamination step in a B-stage state in order to prevent a decrease in adhesion with the next resin layer 32-36 to be laminated and the generation of unnecessary residual stress. Furthermore, it is preferable to set the exposure amount in each exposure step so that the cumulative exposure amount of the first laminated resin layer 31 at the time when all the resin layers 31-36 are laminated keeps the resin layer 31 in a B-stage state.

In the layer number confirmation process in step S25, it is confirmed whether all the necessary resin layers 31 to 36 have been formed, that is, whether the loop parameter n has reached the number of resin layers 31 to 36 to be formed. If all the resin layers 31 to 36 have been formed, this process ends, but if not all the resin layers 31 to 36 have been formed, the process proceeds to step S26.

In the loop parameter addition process of step S26, 1 is added to the loop parameter n. Once the loop parameter n has been added, the process returns to step S2 to form the next resin layer 31-36.

In this way, in the process of forming the frame 30, by making the amount of exposure immediately after lamination of at least one of the resin layers 31-36 different from the amount of exposure immediately after lamination of the other resin layers 31-36, it is possible to form the frame 30 into an accurate shape while improving the strength and adhesion of the frame 30. For example, the amount of exposure immediately after lamination of some of the resin layers 31-36 may be made different from the amount of exposure immediately after lamination of the other resin layers 31-36, or the amount of exposure immediately after lamination of each of the resin layers 31-36 may be gradually changed.

In particular, the strength of the frame 30 can be improved by making the exposure amount immediately after lamination of the last resin layer 36 different from the exposure amount immediately after lamination of the other resin layers 31 to 36. Specifically, the exposure amount of the last resin layer 31 is set to an exposure amount that can harden the photosensitive resin composition to a B-stage state, and the exposure amount of the other resin layers 32 to 36 is set to a minimum exposure amount that hardens the photosensitive resin composition to an extent that it can support the next resin layers 33 to 36, thereby suppressing the generation of residual stress inside the frame 30 and improving the thermal shock resistance of the frame 30. In addition, by setting the exposure amount of the last resin layer 36 to a minimum exposure amount that hardens the photosensitive resin composition to an extent that it can support the solid-state imaging element 20, and setting the exposure amount of the other resin layers 31 to 35 to an exposure amount that can harden the photosensitive resin composition to a B-stage state, the frame 30 is given strength that can maintain its shape in the element bonding process, while improving the adhesion between the frame 30 and the solid-state imaging element.

In the element bonding process of step S3, the solid-state imaging element 20 is bonded to the side of the frame 30 opposite the transparent substrate 40. The frame 30 and the solid-state imaging element 20 are preferably bonded together by welding the final resin layer 36 to the solid-state imaging element 20 by thermocompression bonding. By not using an adhesive, errors in the relative positions of the solid-state imaging element 20 and the transparent substrate 40 caused by variations in the thickness of the adhesive, etc., can be prevented.

The solid-state imaging device package 1 manufactured by the above-described solid-state imaging device package manufacturing method has a frame 30 formed from a photosensitive resin composition on a transparent substrate 40, so that the positioning precision of the frame 30 is high and the image quality of the captured image is high. Furthermore, in the solid-state imaging device package manufacturing method of this embodiment, the frame 30 is formed stepwise by dividing it into multiple resin layers 31 to 36, and the exposure amount of the resin layers 31 to 36 is made different, so that the strength of the frame 30 and its adhesion to the solid-state imaging device 20 can be ensured, thereby improving reliability.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications and variations are possible. In the solid-state imaging element package manufacturing method according to the present invention, a frame may be formed on one of the solid-state imaging element and the transparent substrate, and the other may be bonded to the frame. Alternatively, a frame may be formed on the solid-state imaging element, and the transparent substrate may be bonded to the frame. In the above-mentioned embodiment, the exposure amount of the resin layer, etc., is set sequentially using loop parameters, but modifications such as forming the frame according to a program that describes the formation conditions of all the resin layers in order are possible.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

<Photosensitive resin composition>
As a material for forming the frame, a photosensitive resin composition was prepared by mixing 100 parts by weight of a main polymer having a cyclic polysiloxane structure in the main chain and having a cationic polymerizable group and an alkali-soluble group, 15 to 40 parts by weight of an alicyclic epoxy compound "Celloxide 2021P" manufactured by Daicel Corporation, 3 parts by weight of a photocationic polymerization initiator "CPI-210S" manufactured by San-Apro Co., Ltd., 0.1 parts by weight of an antioxidant "IRGANOX1010" manufactured by BASF Corporation, and 0 parts by weight or 5 parts by weight of fumed silica "R974" (specific surface area 200), "R8200" (specific surface area 200) or "R972" (specific surface area 130) manufactured by Nippon Aerosil Co., Ltd. as a filler. The alicyclic epoxy compound was blended for the purpose of adjusting the glass transition point of the photosensitive resin composition.

The main polymer was prepared by the following procedure. First, 124 mg of platinum vinylsiloxane complex xylene solution "Pt-VTSC-3X" manufactured by Umicore Precious Metals Japan was added to a mixture of 40 g of diallyl isocyanurate, 29 g of diallyl monomethyl isocyanurate, and 264 g of 1,4-dioxane to obtain solution L1. Separately, 88 g of 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane was dissolved in 176 g of toluene to obtain solution L2. Then, in a nitrogen atmosphere containing 3% by volume of oxygen, solution L1 was dropped into solution L2 over a period of 3 hours while solution L2 was heated to a temperature of 105°C. After the dropwise addition, the mixture was stirred for 30 minutes while maintaining the temperature at 105°C to obtain solution L3. The reaction rate of the alkenyl group of the compound contained in the obtained solution L3 was measured by 1H-NMR, and the reaction rate was 95% or more. Separately, 62 g of 1-vinyl-3,4-epoxycyclohexane was dissolved in 62 g of toluene to obtain solution L4. Then, in a nitrogen atmosphere containing 3% by volume of oxygen, solution L3 was heated to a temperature of 105°C, and solution L4 was added dropwise to solution L3 over 1 hour. After completion of the addition, the temperature was kept at 105°C and the mixture was stirred for 30 minutes to obtain solution L5. The reaction rate of the alkenyl group of the compound contained in the obtained solution L5 was measured by 1H-NMR, and the reaction rate was 95% or more. Next, solution L5 was cooled, and the solvent (toluene, xylene, and 1,4-dioxane) was distilled off from solution L5 under reduced pressure to obtain a main polymer. The main polymer had multiple cationic polymerizable groups and multiple alkali-soluble groups in one molecule, and had a cyclic polysiloxane structure in the main chain.

<Prototype of solid-state imaging device package>
A frame was formed on a transparent substrate using the photosensitive resin composition, and solid-state imaging device package prototypes 1 to 10 were produced. Specifically, a plurality of frames having a square tubular structure with a line width of 200 μm and a thickness of 50 μm were formed on a transparent substrate (10 cm×10 cm, thickness 0.4 mm), a dicing film was temporarily attached to the surface of the transparent substrate on which the frame was not provided, and then the substrate was cut with a dicing blade, and the dicing film was peeled off to obtain a framed transparent substrate that was divided into individual pieces. Next, the obtained framed transparent substrate and a mounting substrate on which a solid-state imaging device was mounted were laminated, and a load of 500 g was applied for 30 seconds on a hot plate at a temperature of 120° C. to thermocompress the solid-state imaging device and the frame, and the photosensitive resin composition was completely cured in an oven at 200° C. to obtain a solid-state imaging device package prototype. As the mounting substrate, a wiring substrate was used that provides wiring for connecting the solid-state imaging device to the outside. After the solid-state imaging element and the frame were bonded together, a sealing resin was applied to the outer periphery of the mounting substrate to seal the solid-state imaging element, the frame, and the outer periphery of the transparent substrate.

In prototypes 1 to 3, a frame having 10 resin layers was formed by repeatedly laminating the photosensitive resin composition and forming a resin layer by exposing to ultraviolet light using an inkjet 3D printer. In prototypes 4 to 6, a frame having 10 resin layers was formed using a stereolithography 3D printer. In prototypes 7 to 9, a frame having 10 resin layers was formed using a screen printer. In prototype 10, a dispenser was used, and in prototypes 1, 4, and 7, the amount of exposure to ultraviolet light immediately after laminating the first to ninth layers of the photosensitive resin composition was 10 mJ, and the amount of exposure to ultraviolet light immediately after laminating the tenth layer of the photosensitive resin composition was 500 mJ (exposure amount pattern 1). In prototypes 2, 5, and 8, the amount of exposure to ultraviolet light immediately after laminating the first to ninth layers of the photosensitive resin composition was 500 mJ, and the amount of exposure to ultraviolet light immediately after laminating the tenth layer of the photosensitive resin composition was 10 mJ (exposure amount pattern 2). In prototypes 3, 6, and 9, the amount of exposure to ultraviolet light immediately after lamination of all 10 layers of photosensitive resin composition was 500 mJ (exposure amount pattern 3). In prototype 10, the amount of exposure to ultraviolet light immediately after dispensing was 500 mJ (exposure amount pattern 4). The photosensitive resin composition is cured to the B-stage state by an exposure of 500 mJ of ultraviolet light.

<Evaluation of solid-state imaging device packages>
[Die shear strength]
For each prototype of the solid-state imaging device package, a test was conducted to peel the transparent substrate from the solid-state imaging device using a die shear tester "SERIES4000" manufactured by DAGE Co., Ltd., and the maximum peel load was taken as the die shear strength. Specifically, the die shear strength was measured in accordance with MIL Standard 883 at a shear height of 50 μm and a shear speed of 80 μm/s. The higher the die shear strength, the higher the adhesiveness and the higher the reliability against thermal shocks and the like.

[Thermal shock resistance]
For each prototype of the solid-state imaging device package, a heat shock tester "Cosmopia S" manufactured by Hitachi Johnson Controls Air Conditioning was used to hold the device in an atmosphere of -50°C for 30 minutes, followed by 500 cycles of holding the device in an atmosphere of 125°C for 30 minutes. Next, the optical semiconductor device was observed from the glass substrate side with an optical microscope, and the number of cracked parts of the frame and the number of peeled parts of the frame were counted. Then, the device with the total number of cracked parts and the number of peeled parts being less than 5 was rated as "A", the device with the total number of cracked parts and the number of peeled parts being 5 or more but less than 10 was rated as "B", and the device with the total number of cracked parts and the number of peeled parts being 10 or more was rated as "C".

The frame formation method, exposure pattern, die shear strength, and thermal shock resistance for each prototype solid-state imaging device package are summarized in Table 1 below.

Whether an inkjet 3D printer, a stereolithography 3D printer, or a screen printer is used, it has been confirmed that by making the amount of exposure immediately after lamination of at least one resin layer different from the amount of exposure immediately after lamination of the other resin layers, it is possible to improve thermal shock resistance more than if the amount of exposure immediately after lamination of the resin layers was constant. Furthermore, it has been confirmed that the die shear strength can be improved by making the amount of exposure immediately after lamination of the last resin layer smaller than the amount of exposure immediately after lamination of the other resin layers.

REFERENCE SIGNS LIST 1 solid-state imaging device package 10 mounting substrate 20 solid-state imaging device 21 functional section 22 margin section 23 connection section 30 frame 31 to 36 resin layer 40 transparent substrate 50 sealing material

Claims (5)

A method for manufacturing a solid-state imaging element package including a solid-state imaging element having a functional section for capturing an image and a margin section surrounding the functional section, a frame disposed in the margin section, and a transparent substrate fixed to the frame so as to cover the functional section, comprising:
forming the frame having a plurality of resin layers on one of the solid-state imaging element and the transparent substrate by repeating a process of laminating a photosensitive resin composition and forming a resin layer by exposure two or more times;
bonding the other of the solid-state imaging element and the transparent substrate to the frame;
Equipped with
A method for manufacturing a solid-state imaging element package, in which, in the process of forming the frame, the amount of exposure immediately after lamination of at least one of the plurality of resin layers is made different from the amount of exposure immediately after lamination of other resin layers of the plurality of resin layers. The method for manufacturing a solid-state imaging device package according to claim 1, wherein in the step of forming the frame, the amount of exposure immediately after laminating the last resin layer of the plurality of resin layers is made different from the amount of exposure immediately after laminating the other resin layers of the plurality of resin layers. The method for manufacturing a solid-state imaging device package according to claim 2, wherein in the step of forming the frame, the amount of exposure immediately after laminating the last resin layer is made smaller than the amount of exposure immediately after laminating the other resin layers. The method for manufacturing a solid-state imaging device package according to claim 2, wherein the exposure amount immediately after lamination of the final resin layer is an exposure amount that keeps the photosensitive resin composition in a B-stage state. The method for manufacturing a solid-state imaging device package according to claim 1, wherein the amount of exposure immediately after laminating at least one of the multiple resin layers is an amount of exposure that keeps the photosensitive resin composition in a B-stage state.

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