Overcurrent protection element

Abstract

An overcurrent protection element includes a first electrode layer, a second electrode layer, and a stack of PTC material layers disposed therebetween. The PTC material layers include a fluorine-containing high polymer base material having a melting point higher than 150°C and carbon black. The fluorine-containing high polymer base material includes a fluorine-containing high polymer having a melting point higher than 150°C. The carbon black is dispersed in the fluorine-containing high polymer base material. The overcurrent protection element has a resistance jump R jump_1000@16V / 50A of 0.80 to 1.20 after 1000 cycles at 16V / 50A. The overcurrent protection element has a resistance jump R jump_1000@25V / 50A of 0.90 to 1.30 after 1000 cycles at 25V / 50A.

Description

TECHNICAL FIELD

[0001] The present application relates to an over-current protection element, and more particularly to a small-sized over-current protection element with excellent voltage endurance, high current carrying capacity per unit area, and good resistance jump characteristics. BACKGROUND

[0002] The resistance of a conductive composite material with positive temperature coefficient (PTC) characteristics is sensitive to temperature changes, and thus can be used as a material for a current sensing element. PTC conductive composite materials are widely used in over-current protection elements or circuit elements. The resistance of a PTC conductive composite material at normal temperature is very low, allowing the circuit or battery to operate normally. However, when an over-current or over-temperature phenomenon occurs in the circuit or battery, the resistance of the PTC conductive composite material will instantaneously increase to a high resistance state (at least 10 4 Ω or higher), which is called tripping, and thus reversely offsets the excess current to protect the battery or circuit element.

[0003] An over-current protection element includes a PTC element and an external electrode layer or a pin attached to the outer surface of the PTC element. The PTC element is composed of a PTC material layer and metal foils on both sides of the PTC material layer, wherein the PTC material layer includes a high molecular polymer substrate and conductive fillers uniformly dispersed in the high molecular polymer substrate. Fluorine-containing high molecular polymers are usually used as the high molecular polymer substrate for over-current protection elements used in high temperature environments. With the development of electronic products, there is an increasing demand for light, thin, short, and small electronic products, and the size and thickness of various active and passive elements are also more strictly limited. However, when the size of a conventional over-current protection element is reduced, the voltage endurance is reduced, and the element cannot withstand large current and large power. This makes small-sized over-current protection elements prone to burnout in actual applications. In addition, generally, the resistance recovery of small-sized over-current protection elements is poor, that is, the resistance jump value is too large or too small, and cannot be controlled within an appropriate value range. SUMMARY

[0004] The present application provides an overcurrent protection element, by controlling the appropriate volume ratio of carbon black and fluorine-containing polymer, the size of the element can be further reduced, and has excellent voltage resistance characteristics and good resistance jump value range, while achieving high unit area can withstand power and low energy consumption excellent electrical characteristics. In addition, the overcurrent protection element of the present application is very suitable for use in small electronic products, and can be applied to the environment prone to high temperature.

[0005] According to an embodiment of the present application, an overcurrent protection element includes a first electrode layer, a second electrode layer, and a PTC material layer disposed therebetween. The PTC material layer includes a polymer base material and carbon black. The polymer base material includes a fluorine-containing polymer having a melting point higher than 150°C, and the volume percentage of the polymer base material is 55-65%. The carbon black is dispersed in the polymer base material, and the volume percentage of the carbon black is 30-34%. The overcurrent protection element has a resistance jump R jump_1000@16V / 50A of 0.80-1.20 after 1000 cycles at 16V / 50A. The overcurrent protection element has a resistance jump R jump_1000@25V / 50A of 0.90-1.30 after 1000 cycles at 25V / 50A.

[0006] In an embodiment, the fluorine-containing polymer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, perfluoroalkoxy-modified tetrafluoroethylene, poly(chloro-trifluoro-tetrafluoroethylene), vinylidene-tetrafluoroethylene polymer, tetrafluoroethylene-perfluorodioxole copolymer, vinylidene-hexafluoropropylene copolymer, and vinylidene-hexafluoropropylene-tetrafluoroethylene terpolymer.

[0007] In an embodiment, the PTC material layer further includes a flame retardant selected from the group consisting of halogen or phosphorus flame retardant compounds, metal hydroxides, metal oxides, nitrides, and mixtures thereof, and the volume percentage of the flame retardant in the PTC material layer is 2-10%.

[0008] In an embodiment, the thickness of the PTC material layer is 0.12-0.20mm.

[0009] In an embodiment, the top view area of the PTC material layer is 50-75mm 2 .

[0010] In an embodiment, the overcurrent protection element can pass 1000 cycles of 16V / 50A and 25 / 50A cycle life tests without burning out.

[0011] In one embodiment, the overcurrent protection element has a withstanding current per unit area of 0.070 to 0.100 A / mm 2 .

[0012] In one embodiment, the overcurrent protection element has a withstanding power per unit area of 1.70 to 2.5 W / mm 2 .

[0013] In one embodiment, the overcurrent protection element has an energy consumption of 1.70 to 2.30 W at 25°C under 16 V and 50 A.

[0014] The overcurrent protection element of the present application is very suitable for use in miniaturized electronic products due to its small size. By using a specific ratio of carbon black and fluorine-containing high molecular polymer, excellent electrical characteristics of high withstanding power per unit area and low energy consumption can be achieved. In addition, the element has excellent voltage resistance and a good range of resistance jump values. The overcurrent protection element of the present application is suitable for use in high-temperature overcurrent protection applications. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 shows a cross-sectional side view of a PTC element according to one embodiment of the present application;

[0016] Figure 2 shows a top view of the PTC element of Figure 1 ;

[0017] Figure 3 shows a perspective view of a plug-in overcurrent protection element according to one embodiment of the present application;

[0018] Figure 4 shows a side view of the plug-in overcurrent protection element of Figure 3 ;

[0019] Figure 5 shows a cross-sectional side view of a surface-adhesion element type overcurrent protection element according to one embodiment of the present application.

[0020] In the drawings, the following reference numerals are used:

[0021] 10: PTC element

[0022] 11: PTC material layer

[0023] 12: First electrode layer

[0024] 13: Second electrode layer

[0025] 14: Insulating coating layer

[0026] 15, 16: Pin

[0027] 20, 30: Overcurrent protection element

[0028] 31: Gap

[0029] 32: Insulation layer

[0030] 33, 33': Outer electrode layer

[0031] 34, 34': Vertical through holes Detailed Implementation

[0032] To make the above and other technical contents, features and advantages of the present invention more apparent and understandable, relevant embodiments are provided below, and detailed descriptions are given in conjunction with the accompanying drawings.

[0033] Table 1 shows the formulation composition and PTC material layer thickness of each example (E1-E4) and comparative example (C1-C4) as a volume percentage. In this experiment, the fluorinated polymers in the polymer substrate included polyvinylidene difluoride (PVDF) and polytetrafluoroethylene (PTFE), wherein the PVDF selected had a melting point of 165°C. For product 761A, the PTFE used is DuPont Zonyl™ PTFE MP1000 with a melting point of 315°C. The fluorinated polymers in E1–E4, as mentioned above, include PVDF and PTFE, and together account for 63–65% of the volume percentage of the PTC material layer. The fluorinated polymers in C1–C4 account for 62% of the volume percentage of the PTC material layer. The conductive fillers in both E1–E4 and C1–C4 are made of carbon black (CB), which has relatively stable electrical properties. Specifically, CB accounts for 32–34% of the volume percentage of the PTC material layer in E1–E4, and 35% in C1–C4. In addition, E1 to E4 and C1 to C4 contain 3% magnesium hydroxide (Mg(OH)2) by volume in the PTC material layer. Magnesium hydroxide can not only act as a flame retardant, but also avoid the effects of hydrofluoric acid generated at high temperatures when the conductive filler and fluorinated polymer are mixed, and its influence on the component characteristics.

[0034] Since miniaturization is the future trend for overcurrent protection components, the thickness of the PTC material layer in E1 to E4 has been reduced to 0.14–0.20 mm. Furthermore, the top-view area of ​​the PTC material layer in E1 to E4 has also been reduced, with a width of 7.62 mm and a length of 9.35 mm. Therefore, the area of ​​the PTC material layer or PTC element (i.e., "PTC wafer") is 7.62 × 9.35 = 71.2 mm². 2The PTC material layers of C1-C2 also have a width of 7.62 mm and a length of 9.35 mm, so the area is 7.62 x 9.35 = 71.2 mm 2 However, the thickness of the PTC material layers of C1-C2 is relatively thick, which is 0.26 mm and 0.36 mm, respectively. C3-C4 are conventional PTC elements, which have a larger size than E1-E4. The PTC material layers of C3-C4 have a width of 8 mm and a length of 12 mm, so the area is 8.0 x 12.0 = 96.0 mm 2 and the thickness of the PTC material layers of C3-C4 is 0.26 mm and 0.36 mm, respectively.

[0035] Table 1

[0036]

[0037] The materials of each example and comparative example in Table 1 were added to a twin-screw mixer produced by HAAKE Co. in the volume percentage shown and mixed. The mixing temperature was set to 215°C, the pre-mixing time was 3 minutes, and the mixing time was 15 minutes. The conductive polymer after mixing was pressed into a sheet by a hot press at 210°C and a pressure of 150 kg / cm 2 After that, the sheet was cut into a square of about 20 cm x 20 cm, and two nickel-plated copper foils were attached to both sides of the sheet by a hot press at 210°C and a pressure of 150 kg / cm 2 Finally, a plurality of PTC chips were punched out by a punch press, thereby forming the PTC element of the present application. In one example, the PTC element 10 of the present application is shown in Figure 1 Figure 2 Figure 1 is a top view of the PTC element 10. The PTC element 10 includes a PTC material layer 11 composed of the conductive polymer and a first electrode layer 12 and a second electrode layer 13 composed of the nickel-plated copper foil. The area "A x B" of the PTC element 10 is equivalent to the area of the PTC material layer 11. The length "A", the width "B", and the thickness of the PTC material layer 11 of E1-E4 and C1-C4 of Table 1 are as described above, so the PTC element 10 formed has a rectangular parallelepiped structure.

[0038] Next, as shown in Figure 3 and Figure 4 ​​As shown, solder paste is applied to the outer surfaces of the first and second electrode layers 12 and 13. Two copper electrode sheets with a thickness of 0.5 mm are placed on the solder paste on the outer surfaces of the first and second electrode layers 12 and 13 as leads 15 and 16, respectively. The assembled component is then subjected to a 300°C reflow soldering process to obtain a radial-lead type overcurrent protection component 20. Furthermore, an insulating coating layer 14, such as an epoxy resin layer, can be applied to the outer surface of the component. The epoxy resin layer serves as an encapsulation layer, preventing water and oxygen from the external environment from invading the component 20 and causing deterioration of its electrical characteristics. In one embodiment, in addition to the radial-lead type overcurrent protection component 20, an axial-type overcurrent protection component can also be manufactured. Alternatively, as... Figure 5 As shown, notches 31 are etched into the first and second electrode layers 12 and 13 using relevant processes. Then, an insulating layer 32, outer electrode layers 33 and 33', and vertical vias 34 and 34' are fabricated to form a surface-mount device (SMD) type overcurrent protection element 30. The vertical vias 34' connect the first electrode layer 12 and the outer electrode layer 33, and the vertical vias 34' connect the second electrode layer 13 and the outer electrode layer 33'. That is, the overcurrent protection elements 20 and 30 of the present invention include a PTC element 10, and by forming pins 15 and 16 or outer electrode layers 33 and 33' on the outer surface of the PTC element 10, the pins 15 and 16 or the outer electrode layers 33 and 33' are electrically connected to the first and second electrode layers 12 and 13, and electrically connected to an external circuit, thereby providing current protection.

[0039] The overcurrent protection element 20 with the above different formulations was subjected to the following resistance measurements: (1) initial resistance value Ri; (2) resistance value R1000@16V / 50A after 1000 cycles (on: 10 seconds; off: 60 seconds) at 16V / 50A; and (3) resistance value R1000@25V / 50A after 1000 cycles (on: 10 seconds; off: 60 seconds) at 25V / 50A. Each cycle represents one trigger and recovery process, and the results are recorded in Table 2 below. In addition, (R1000@16V / 50A) / (Ri) was calculated, and (R1000@16V / 50A) / (Ri) was defined as the resistance jump R after 1000 cycles at 16V / 50A. jump_1000@16V / 50A R jump_1000@16V / 50A= (R1000@16V / 50A) / (Ri), to thereby evaluate the degree of change in the resistance value of the element after 1000 cycles at 16V / 50A. Also, (R1000@25V / 50A) / (Ri) is calculated, and (R1000@25V / 50A) / (Ri) is defined as the resistance jump R jump_1000@25V / 50A , i.e., R jump_1000@25V / 50A = (R1000@25V / 50A) / (Ri), to thereby evaluate the degree of change in the resistance value of the element 20 after 1000 cycles at 25V / 50A. In other words, if the value of the resistance jump is equal to 1, it means that the resistance value after 1000 cycles has not changed compared to the initial resistance value Ri. Conversely, if the value of the resistance jump is too large or too small, it means that the resistance value after 1000 cycles has a large change compared to the initial resistance value Ri. In the present test, the conditions of 16V / 50A or 25V / 50A are each performed 1000 times in order to perform a cycle life test, which is evaluated by testing the voltage endurance of the element 20. If the element 20 does not burn out after the cycle life test is completed, it is marked as "pass"; otherwise, if the element 20 burns out during the cycle life test, it is marked as "fail".

[0040] Table 2

[0041]

[0042] From Table 2, it can be seen that although the area of the PTC material layer of Examples El to E4 is reduced and the thickness of the PTC material layer is thinned, by matching the appropriate volume ratio of carbon black (C.B.) and fluorine-containing polymer, the resistance jump R jump_1000@16V / 50A of El to E4 is between 0.82 and 1.10, and the resistance jump R jump_1000@25V / 50A of El to E4 is between 0.92 and 1.23. The area of the PTC material layer of Cl to C2 is the same as that of El to E4, but the thickness of the PTC material layer is relatively thick, and the test results show that the resistance jump R jump_1000@16V / 50A of Cl to C2 is between 0.62 and 0.65, and the resistance jump R jump_1000@25V / 50Abetween 0.66 and 0.70. Obviously, the resistance value change degree of Comparative Examples C1-C4 after the cycle test is larger than that of Examples El-E4; as a result, this is because the content of the conductive filler carbon black in the PTC material layer of El-E4 is less than that of C1-C4, so that El-E4 has an excellent resistance jump, i.e., a better resistance recovery. Comparative Examples C3-C4 are conventional PTC elements, in which the width, length and thickness of the PTC material layer are much larger than those of El-E4, and the volume ratio of carbon black in the PTC material layer is 35%, and the test results show that the resistance jump R jump_1000@16V / 50A between 0.61 and 0.74, and the resistance jump R jump_1000@25V / 50A between 0.72 and 0.74. Similarly, the resistance value change degree of Comparative Examples C3-C4 after the cycle test is also larger than that of Examples El-E4.

[0043] Although the size of the overcurrent protection element of Examples El-E4 is reduced, the test results show that the element can "pass" the cycle life test of 16V / 50A and 25V / 50A, i.e., the overcurrent protection element is not burned. The thickness of the PTC material layer of Comparative Examples C1-C4 is thicker than that of Examples El-E4, so that it is expected that the element should have a good voltage resistance characteristic, and the overcurrent protection element does not burn during the voltage resistance test.

[0044] In addition, 5 overcurrent protection elements of El-E4 and C1-C4 are taken as samples to verify the bearable power and energy consumption, and the following measurements are performed on the overcurrent protection element: (1) the trigger current I-trip at 25°C; and (2) the leakage current when the element is triggered by applying 16V, 50A at 25°C. According to the trigger current and the element area, the trigger current value per unit area (A / mm 2 ) and the bearable power per unit area (W / mm 2 ) can be calculated. The trigger current value per unit area (A / mm 2 ) is used to evaluate the bearable current per unit area (A / mm 2 ). When 16V, 50A is applied at 25°C, the overcurrent protection element will be triggered, but because the current cannot be completely cut off, the element will have a leakage current. According to the leakage current and the voltage value 16V that will not burn the element, the power dissipation (W) of the element at 25°C under 16V, 50A can be calculated. Table 3 shows the test results of each of Examples El-E4 and Comparative Examples C1-C4.

[0045] Table 3

[0046]

[0047] As shown in Table 2, although the area and thickness of the PTC material layer in Examples E1 to E4 are smaller, by combining appropriate volume proportions of carbon black (CB) and fluorinated polymers, the trigger current value per unit area (current withstandable per unit area) (A / mm²) of the overcurrent protection element in Examples E1 to E4 remains high. 2 The range is 0.069–0.097 A / mm. 2 Between [specific values]. The overcurrent protection elements of comparative examples C1 to C4 have a current-carrying capacity per unit area of ​​0.056 to 0.062 A / mm². 2 Between these values, it can be seen that, compared to C1-C4, the overcurrent protection elements E1-E4 have excellent current-carrying capacity per unit area. Furthermore, since the current-carrying capacity per unit area of ​​E1-E4 is higher than that of C1-C4, the power-carrying capacity per unit area of ​​E1-E4 is also higher than that of C1-C4, ranging from 1.726 to 2.414 W / mm². 2 between.

[0048] When 16V and 50A are applied at 25℃, the component will trigger, and the power consumption (W) can be calculated by measuring the leakage current of the component. Table 2 shows that the leakage current of E1 to E4 is between 0.112 and 0.139A, which is less than the leakage current of C1 to C4, which is between 0.151 and 0.177A. Therefore, it can also be seen that the power consumption of E1 to E4 is less than that of C1 to C4, with the power consumption of E1 to E4 between 1.79 and 2.22W, and the power consumption of C1 to C4 between 2.42 and 2.83W.

[0049] Examples E1 to E4 use a PTC material layer with a top-view area of ​​71.2 mm². 2 The thickness was verified to be between 0.14 and 0.20 mm. In fact, according to the inventors' actual tests, the top-view area of ​​the PTC material layer can be 50–75 mm². 2 (e.g., 55mm) 2 60mm 2 65mm 2 Or 70mm 2 The thickness of the PTC material layer can be 0.12 to 0.20 mm (e.g., 0.14 mm, 0.16 mm, or 0.18 mm), which can give this small-sized overcurrent protection element excellent electrical characteristics such as excellent voltage resistance, good resistance bounce range, high current withstand per unit area, high power withstand per unit area, and low energy consumption.

[0050] In summary, the overcurrent protection element of the present application can be in the form of a plug-in type, a shaft type or a surface-adhesion element type. The polymer of the PTC material layer in the overcurrent protection element is a fluorine-containing polymer having a volume percentage of 55-65%, or for example, 57%, 60% or 63%; the conductive filler can be Carbon Black (C.B.) having a volume percentage of 30-34%, or for example, 31%, 32% or 33%. Preferably, the PTC material layer can further include a flame retardant such as magnesium hydroxide (Mg(OH)2) having a volume percentage of 2-10%, or for example, 4%, 6% or 8%. By combining Carbon Black (C.B.) and the fluorine-containing polymer in appropriate volume percentages, the small-size overcurrent protection element of the present application can pass the 16V / 50A and 25 / 50A cycle life tests without burning out after 1000 cycles; the resistance bounce R jump_1000@16V / 50A after 1000 cycles at 16V / 50A is 0.80-1.20, for example, 0.90, 1.00 or 1.10; and the resistance bounce R jump_1000@25V / 50A after 1000 cycles at 25V / 50A is 0.90-1.30, for example, 1.00, 1.10 or 1.20. At the same time, the element can achieve excellent electrical characteristics such as high current-carrying capacity per unit area, high power-carrying capacity per unit area and low energy consumption. Because the element's voltage resistance can be increased to 25V, the element's current-carrying capacity per unit area is increased to 0.070-0.100 A / mm 2 (for example, 0.080 A / mm 2 or 0.090 A / mm 2 ), and the element's power-carrying capacity per unit area is also increased to 1.70-2.5 W / mm 2 (for example, 1.90 W / mm 2 , 2.10 W / mm 2 or 2.30 W / mm . Furthermore, the element's energy consumption at 25°C under 16V, 50A is between 1.70 and 2.30 W, for example, 1.90 W or 2.10 W.

[0051] The overcurrent protection element of the present invention is applied in high temperature environment, so the fluoropolymer is preferably selected to have a melting point greater than 150°C. The fluoropolymer added in the present invention is not limited to PVDF and PTFE, and other fluoropolymers having similar properties and a melting point higher than 150°C are also covered by the present invention. For example: polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoro-propylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (PETFE), perfluoroalkoxy modified tetrafluoroethylenes (PFA), poly(chlorotri-fluorotetrafluoroethylene) (PCTFE), vinylidene fluoride-tetrafluoroethylene copolymer (VF-2-TFE), poly(vinylidene fluoride), tetrafluoroethylene-perfluorodioxole copolymers, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, etc. Preferably, a plurality of fluoropolymers having different melting points can be selected. Because of the different melting points, a relatively flat resistance-temperature curve (R-T curve) can be obtained, which improves the stability of the cycle life test and better withstand voltage characteristics.

[0052] The flame retardant can be a halogen or phosphorus is a flame retardant compound, metal hydroxide (such as: Al2(OH)3, Mg(OH)2), metal oxide (such as: ZnO, Sb2O3), nitride (such as BN) or mixture thereof, etc.

[0053] The overcurrent protection element of the present application has small size, but still has excellent voltage resistance, and the resistance jump is neither too large nor too small, while achieving high current carrying capacity per unit area, high power carrying capacity per unit area, low energy consumption, and other excellent electrical properties, and is suitable for use in high-temperature overcurrent protection applications.

Claims

1. An overcurrent protection element, comprising: a first electrode layer; a second electrode layer; and a PTC material layer stacked between the first electrode layer and the second electrode layer, the PTC material layer comprising: a high molecular polymer base material comprising a fluorine-containing high molecular polymer having a melting point higher than 150°C, the high molecular polymer base material having a volume percentage of 55-65%; and carbon black dispersed in the high molecular polymer base material, the carbon black having a volume percentage of 30-34%. wherein the overcurrent protection element has a resistance jump R after 1000 cycles at 16 V / 50 A jump_1000@16V / 50A is 0.80 to 1.20; wherein the overcurrent protection element has a resistance jump R after 1000 cycles at 25 V / 50 A of jump_1000@25V / 50A 0.90 to 1.

30.

2. The overcurrent protection element according to claim 1, wherein the fluorine-containing high molecular polymer comprises at least one of polydifluoroethylene, polytetrafluoroethylene, polyfluorinated vinylidene, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, perfluoroalkoxy-modified tetrafluoroethylene, poly(chloro-trifluorotetrafluoroethylene), vinylidene-tetrafluoroethylene polymer, tetrafluoroethylene-perfluorodioxole copolymer, vinylidene-hexafluoropropylene copolymer, and vinylidene-hexafluoropropylene-tetrafluoroethylene terpolymer.

3. The overcurrent protection element according to claim 1, wherein the PTC material layer further comprises a flame retardant selected from the group consisting of halogen or phosphorus flame retardant compounds, metal hydroxide compounds, metal oxide compounds, nitride compounds, and mixtures thereof, the flame retardant having a volume percentage of 2-10% in the PTC material layer.

4. The overcurrent protection element according to claim 1, wherein the PTC material layer has a thickness of 0.12-0.20 mm.

5. The overcurrent protection element according to claim 1, wherein the PTC material layer has an upper surface area of 50-75 mm2.

6. The overcurrent protection element according to claim 1, wherein the overcurrent protection element can pass 16V / 50A and 25 / 50A cycle life tests for 1000 cycles without burnout.

7. The overcurrent protection element according to claim 1, wherein the overcurrent protection element has a unit area current withstand of 0.070-0.100 A / mm2.

8. The overcurrent protection element according to claim 1, wherein the overcurrent protection element has a unit area power withstand of 1.70-2.5 W / mm2.

9. The overcurrent protection element according to claim 1, wherein the overcurrent protection element has an energy consumption of 1.70-2.30 W at 25°C under an applied voltage of 16V and a current of 50A.

Images