Microelectronic magnetic force automatic detection device
By combining a hollow suction cup, a material collection plate, and a linkage mechanism, automated material collection for the microelectronic magnetic detection device is achieved, solving the problem of slow manual material collection, improving detection efficiency and probe stability, and ensuring accurate temperature control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-04-10
AI Technical Summary
In the process of magnetic force testing for microelectronics, manual material feeding is slow, which reduces the efficiency of the testing process.
An automatic magnetic detection device for microelectronics was designed. It uses a hollow suction cup and a feeding and collecting plate in conjunction with a motor and a cylinder to realize the automatic fixing and lifting movement of the chip. The stable and automated feeding and collecting of the chip is achieved through a linkage mechanism. The stability of the probe is improved by wave springs and rubber blocks. A cooling pipe box is set up for temperature control.
It improves the speed and convenience of automatic chip feeding and collection, enhances the stability of the probe, reduces the impact of vibration, and improves the overall efficiency and accuracy of the detection process.
Smart Images

Figure CN224109625U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the microelectronic magnetic force detection technical field, specifically a microelectronic magnetic force automatic detection device. BACKGROUND
[0002] In the semiconductor chip production process, many chips such as magnetic storage chips (MRAM, HDD head chip, etc.), sensor chips (such as Hall sensor chip, fluxgate sensor chip) have strict requirements on magnetic force performance, and the microelectronic magnetic force automatic detection device can be used to detect the magnetic parameters of magnetic materials in the chip manufacturing process, such as coercive force, residual magnetism, permeability, etc., to ensure that the chip can work stably in different magnetic field environments, and improve the chip product quality and reliability.
[0003] At present, through long-term observation and use, it is found that in the microelectronic magnetic force detection process, the speed of artificial discharging is slow, and in the large-scale detection process, the frequent discharging and taking operation of artificial will consume a lot of time, which leads to the reduction of the overall efficiency of the detection process, therefore, aiming at the above problems, a microelectronic magnetic force automatic detection device is proposed. UTILITY MODEL CONTENTS
[0004] In order to make up for the deficiencies of the prior art and solve at least one technical problem proposed in the background art, the utility model provides a microelectronic magnetic force automatic detection device.
[0005] The utility model discloses a microelectronic magnetic force automatic detection device, including the bottom plate, the bottom plate end fixedly connected with the placing plate, the placing plate end fixedly connected with the support frame, the support frame end fixedly connected with the first motor, the placing plate side wall fixedly connected with the fixed slide rail frame, the fixed slide rail frame inner side wall fixedly connected with the first motor, the first motor output end sliding connection has the telescopic column, the telescopic column end fixedly connected with the slide rail plate, the slide rail plate inside fixedly connected with the air cylinder, the air cylinder end fixedly connected with the hollow suction cup, the slide rail plate surface fixedly connected with the positioning recess block, the placing plate top is equipped with the discharging collection plate, the placing plate end fixedly connected with the positioning convex block, the positioning convex block surface rotationally connected with right long rotary lever, right long rotary lever and right short rotary lever are slidingly connected, right short rotary lever and discharging collection plate are rotationally connected, right long rotary lever end fixedly connected with the connecting rod, the connecting rod end fixedly connected with left long rotary lever, left long rotary lever and positioning recess block are rotationally connected, left long rotary lever and left short rotary lever are slidingly connected, left short rotary lever and discharging collection plate are rotationally connected, and the discharging collection plate end both sides are all set with the sliding slot.
[0006] Preferably, the bottom plate end is fixedly connected with a sliding plate; the middle part of the sliding plate is fixedly connected with a second motor; the output end of the second motor is rotationally connected with a threaded rod; the surface of the threaded rod is slidably connected with a sliding block; the end of the sliding block is fixedly connected with a display screen; the end of the display screen is fixedly connected with a detection needle; the two sides of the end of the display screen are symmetrically fixedly connected with a plurality of groups of wave-shaped hoses; the end of the wave-shaped hose is fixedly connected with a rubber block; the inside of the wave-shaped hose is provided with a wave-shaped spring; and the wave-shaped spring is fixedly connected with the rubber block.
[0007] Preferably, the end of the placing plate is fixedly connected with a positioning groove block; the two sides of the end of the positioning groove block are fixedly connected with spring assemblies; and the end of the spring assembly is fixedly connected with a receiving ladder block.
[0008] Preferably, the middle part of the placing plate is fixedly connected with a cooling pipeline box; the two sides of the end of the cooling pipeline box are fixedly connected with connecting pipes; and the connecting pipes are in pipeline connection with the condenser.
[0009] Preferably, the end of the bottom plate is fixedly connected with a receiving plate block; and the surface of the receiving plate block is linearly arrayed with cotton strips.
[0010] Preferably, the end of the receiving ladder block is fixedly connected with a smooth piece.
[0011] The microelectronic magnetic force automatic detection device has the advantages that:
[0012] The microelectronic magnetic force automatic detection device has the advantages that: the hollow suction cup and the discharging and collecting plate are arranged, after detection is completed, the detection chip is fixed by the suction cup and is subjected to lifting movement, meanwhile, in the process of lifting movement, the discharging and collecting plate is cooperated with the connecting rod discharging and collecting device, so that automatic stable discharging and collecting of the detection chip is realized, the speed and convenience of collection are improved, and the overall efficiency of the detection process is improved.
[0013] The microelectronic magnetic force automatic detection device has the advantages that: the wave-shaped spring and the rubber block are arranged, the detection needle is moved and arranged, so that the detection needle is in a suitable detection position and the adaptability during detection is improved, the display screen is subjected to buffering and vibration reduction treatment, so that the stability of the detection needle is improved, the vibration effect on the detection needle is reduced, the stability of the detection needle is improved, and the detection effect is improved. BRIEF DESCRIPTION OF DRAWINGS
[0014] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and the schematic embodiments and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.
[0015] In the drawings:
[0016] Figure 1 is a perspective view of the present application.
[0017] Figure 2 is the perspective view of the display screen in the utility model;
[0018] Figure 3 is the perspective view of the hollow suction cup in the utility model;
[0019] Figure 4 is the perspective view of the cooling pipeline box in the utility model;
[0020] Figure 5 is the perspective view of the wave spring in the utility model;
[0021] Figure 6 is the perspective view of the cooling pipeline box in the utility model.
[0022] Legend:
[0023] 1, bottom plate; 11, placing plate; 12, support frame; 13, first motor; 14, fixed slide rail frame; 15, telescopic column; 16, slide rail plate; 17, air cylinder; 18, hollow suction cup; 19, positioning concave block; 101, blanking collection plate; 102, positioning convex block; 103, right long rotary rod; 104, right short rotary rod; 105, connecting rod; 106, left long rotary rod; 107, left short rotary rod; 108, sliding groove; 2, sliding plate; 21, second motor; 22, threaded rod; 23, sliding block; 24, display screen; 25, detection needle; 26, wave-shaped hose; 27, wave spring; 28, rubber block; 3, positioning groove block; 31, spring assembly; 32, receiving ladder block; 4, cooling pipeline box; 41, connecting pipe; 42, condenser; 5, receiving plate block; 51, cotton strip; 6, smooth sheet. DETAILED DESCRIPTION
[0024] The technical solutions in the embodiments of the utility model will be apparently and completely described in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.
[0025] The specific embodiments are given below.
[0026] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4The utility model provides a kind of microelectronic magnetic force automatic detection device, including bottom plate 1;The end of bottom plate 1 is fixedly connected with placing plate 11;The end of placing plate 11 is fixedly connected with support frame 12;The end of support frame 12 is fixedly connected with first motor 13;The side wall of placing plate 11 is fixedly connected with fixed slide rail frame 14;The inner side wall of fixed slide rail frame 14 is fixedly connected with first motor 13;The output end of first motor 13 is slidably connected with telescopic column 15;The end of telescopic column 15 is fixedly connected with slide rail plate 16;The inside of slide rail plate 16 is fixedly connected with cylinder 17;The end of cylinder 17 is fixedly connected with hollow suction cup 18;The surface of slide rail plate 16 is fixedly connected with positioning recess block 19;The top of placing plate 11 is equipped with blanking collecting plate 101;The end of placing plate 11 is fixedly connected with positioning boss 102;The surface of positioning boss 102 is rotatably connected with right long rotary lever 103;Right long rotary lever 103 and right short rotary lever 104 are slidably connected;Right short rotary lever 104 and blanking collecting plate 101 are rotatably connected;The end of right long rotary lever 103 is fixedly connected with connecting rod 105;The end of connecting rod 105 is fixedly connected with left long rotary lever 106;Left long rotary lever 106 and positioning recess block 19 are rotatably connected;Left long rotary lever 106 and left short rotary lever 107 are slidably connected;Left short rotary lever 107 and blanking collecting plate 101 are rotatably connected;The end of blanking collecting plate 101 both sides is equipped with chute 108;When working, after the chip is detected, the first motor 13 is started to drive the telescopic column 15 to move up and down, the telescopic column 15 drives the slide rail plate 16 to slide up and down along the inner side wall of the fixed slide rail frame 14, when the slide rail plate 16 slides down to the hollow suction cup 18 contacts the detected chip, the air cylinder 17 is started to make it contract the gas, so that the hollow suction cup 18 generates suction force to fix the detected chip, the suction force in the hollow suction cup 18 can be generated by the air cylinder 17 to inhale the gas, so as to improve the suction fixing effect of the detected chip, then the first motor 13 is started to drive the slide rail plate 16 to slide up, in the process of sliding, the left long rotating rod 106 slides to the left and rotates, at the same time, the left short rotating rod 107 slides to the left and rotates, at the same time, the right long rotating rod 103 slides to the right and drives the right short rotating rod 104 to rotate to the right, in the process of the movement of the two side connecting rods, the connecting rod 105 slides in the sliding groove 108 to play a guiding role, drives the two side connecting rods to slide to the corresponding direction, the movement of the two side connecting rods can drive the blanking collecting plate 101 to move to the center of the hollow suction cup 18, when the connecting rod 105 slides to the maximum length of the sliding groove 108, the air suction force is contacted by starting the air cylinder 17 again, so that the detected chip falls on the blanking collecting plate 101, then the first motor 13 is started again to drive the hollow suction cup 18 to slide down, in the process, the connecting rod moves in the opposite direction, so that the blanking collecting plate 101 moves out of the range of the hollow suction cup 18 and moves along the external collecting device to collect, the design can realize stable and automatic blanking and collecting of the detected chip by using the suction cup to fix the detected chip and moving up and down, improve the speed and convenience of collecting, and improve the overall efficiency of the detection process.
[0027] Further, as Figure 1 , Figure 5As shown, the end of the bottom plate 1 is fixedly connected with a sliding plate 2; the middle of the sliding plate 2 is fixedly connected with a second motor 21; the output end of the second motor 21 is rotationally connected with a threaded rod 22; the surface of the threaded rod 22 is slidably connected with a sliding block 23; the end of the sliding block 23 is fixedly connected with a display screen 24; the end of the display screen 24 is fixedly connected with a detection needle 25; the two sides of the end of the display screen 24 are symmetrically fixedly connected with a plurality of groups of wave-shaped hoses 26; the end of the wave-shaped hose 26 is fixedly connected with a rubber block 28; the inside of the wave-shaped hose 26 is provided with a wave-shaped spring 27; the wave-shaped spring 27 is fixedly connected with the rubber block 28; when the detection chip is placed, the second motor 21 is started to drive the threaded rod 22 to rotate, the threaded rod 22 drives the sliding block 23 to slide, and the display screen 24 and the detection needle 25 slide, after sliding to the appropriate position, the second motor 21 is turned off, the detection needle 25 is in the appropriate detection position, the detection effect is enhanced, in the process of sliding of the display screen 24, the wave-shaped hose 26, the wave-shaped spring 27 and the rubber block 28 move, in the process of detection of the detection needle 25, the friction between the rubber block 28 and the sliding plate 2 is enhanced, the stability of the detection needle 25 is improved, when the external vibration occurs, the vibration effect on the display screen 24 is buffered and reduced by the high stability of the wave-shaped spring 27, the stability of the display screen 24 is improved, so that the stability of the detection needle 25 is improved, the detection needle is moved and arranged, the adaptability during detection is improved, the vibration of the display screen is reduced, the stability of the detection needle is improved, the vibration effect on the detection needle is reduced, the stability of the detection needle is improved, and the detection effect is improved.
[0028] Further, as shown in Figure 4 The end of the placing plate 11 is fixedly connected with a positioning groove block 3; the two sides of the end of the positioning groove block 3 are fixedly connected with a spring assembly 31; the end of the spring assembly 31 is fixedly connected with a receiving ladder block 32; during the process of sliding down of the blank collecting plate 101, the receiving ladder block 32 is contacted first, at this time, the receiving ladder block 32 supports the blank collecting plate 101, during the process of continuous sliding down of the blank collecting plate 101, the spring assembly 31 is compressed by applying pressure to the receiving ladder block 32, when the spring assembly 31 is compressed, the spring assembly 31 generates a reaction force which is applied to the blank collecting plate 101 through the receiving ladder block 32, so that the sliding speed of the blank collecting plate 101 is limited to a certain extent, and the stability of the blank collecting plate 101 during sliding down is improved, the sliding speed of the blank collecting plate 101 is buffered and limited, the stability of the blank collecting plate 101 during sliding down is improved, and the stability of the detection chip placed on the blank collecting plate 101 during sliding down is improved, and the stability during the blanking process of the chip is improved.
[0029] Further, as shown inFigure 6 As shown in the drawings, the middle of the placement plate 11 is fixedly connected with a cooling pipeline box 4; the end of the cooling pipeline box 4 is fixedly connected with a connecting pipe 41 on both sides; the connecting pipe 41 is connected with a condenser 42 in a pipeline manner; in operation, the condenser 42 is started to run, so that the cooling liquid is transported to the pipeline in the cooling pipeline box 4 through the connecting pipe 41 on one side, and the cooling liquid can be circulated and flowed again through the design of the pipeline in the cooling pipeline box 4, so as to improve the overall cooling effect of the cooling pipeline box 4 on the detection chip placed on the upper part, thereby reducing the change of the magnetic material, the design sets a recyclable cooling liquid device at the lower end of the detection chip, so as to improve the stability of the temperature in the detection process, reduce the influence of temperature rise on the magnetic material, and improve the accuracy of the detection result.
[0030] Further, as shown in the drawings, Figure 2 As shown in the drawings, the end of the bottom plate 1 is fixedly connected with a receiving plate block 5; the surface of the receiving plate block 5 is fixedly connected with a cotton strip 51 in a linear array; in operation, in the process of placing the detection chip on the blanking and collecting plate 101, the detection chip slides into the receiving plate block 5 along the inclination angle and the sliding process of the blanking and collecting plate 101, and is received by the cotton strip 51, and when the detection chip slides into the cotton strip 51, the cotton strip 51 is buffered to stably slide on the receiving plate block 5, so as to facilitate the collection of the staff, the design of the cotton strip reduces the gravity effect when the detection chip slides, reduces the impact on the chip, and improves the stability and safety of the collected chip.
[0031] Further, as shown in the drawings, Figure 4 As shown in the drawings, the end of the receiving plate block 5 is fixedly connected with a cotton strip 51 in a linear array; in operation, in the process of placing the detection chip on the blanking and collecting plate 101, the detection chip slides into the receiving plate block 5 along the inclination angle and the sliding process of the blanking and collecting plate 101, and is received by the cotton strip 51, and when the detection chip slides into the cotton strip 51, the cotton strip 51 is buffered to stably slide on the receiving plate block 5, so as to facilitate the collection of the staff, the design of the cotton strip reduces the gravity effect when the detection chip slides, reduces the impact on the chip, and improves the stability and safety of the collected chip.
[0032] Working principle: when working, after the chip detection is completed, the first motor 13 is started to drive the telescopic column 15 to move up and down, the telescopic column 15 drives the slide rail plate 16 to slide up and down along the inner side wall of the fixed slide rail frame 14, when the slide rail plate 16 slides down to the hollow suction cup 18 contacts the detection chip, the air cylinder 17 is started to make it contract the gas, so that the hollow suction cup 18 generates suction force to fix the detection chip, the suction force in the hollow suction cup 18 can be generated by the air suction of the air cylinder 17, so as to improve the suction fixing effect of the detection chip, then the first motor 13 is started to drive the slide rail plate 16 to slide up, in the process of sliding, the left long rotating rod 106 slides left and rotates, at the same time, the left short rotating rod 107 slides left and rotates, the upper end of the right long rotating rod 103 slides right and drives the right short rotating rod 104 to rotate right, in the process of the movement of the two side connecting rods, the connecting rod 105 slides in the sliding groove 108 to guide the two side connecting rods to slide in the corresponding direction, the movement of the two side connecting rods can drive the blanking collection plate 101 to move to the center of the hollow suction cup 18, when the connecting rod 105 slides to the maximum length of the sliding groove 108, the air suction force is contacted by starting the air cylinder 17 again, so that the detection chip can fall on the blanking collection plate 101, then the first motor 13 is started again to drive the hollow suction cup 18 to slide down, in this process, the connecting rod moves in the opposite direction, so that the blanking collection plate 101 moves out of the range of the hollow suction cup 18 and moves along the external collection device to collect, the design can realize stable and automatic blanking and collection of the detection chip by using the suction cup to fix the detection chip and moving up and down, improve the speed and convenience of collection, improve the overall efficiency of the detection process, when the detection chip is placed, the second motor 21 is started to drive the threaded rod 22 to rotate, the threaded rod 22 drives the sliding block 23 to slide and drives the display screen 24 and the probe needle 25 to slide, after sliding to the appropriate position, the second motor 21 is turned off, the probe needle 25 is in the appropriate detection position, which can enhance the detection effect, in the process of sliding of the display screen 24, the corrugated hose 26, the corrugated spring 27 and the rubber block 28 move, in the position determination, the probe needle 25 detects, the rubber block 28 enhances the friction force with the sliding plate 2 to improve the stability of the probe needle 25 during detection, at the same time, when the external vibration occurs, the corrugated spring 27 has high stability, which can buffer the vibration effect of the display screen 24 to reduce the vibration effect of the display screen 24, so as to improve the stability of the probe needle 25, the design can make the probe needle move to the appropriate detection position to improve the adaptability during detection, and the display screen can be buffered to reduce vibration, so as to improve the stability of the probe needle and reduce the vibration effect of the probe needle.Thus, the stability is improved, and the detection effect is improved. During the sliding of the discharging collecting plate 101, the discharging collecting plate 101 first contacts the receiving ladder block 32, and the receiving ladder block 32 supports the discharging collecting plate 101. During the continuous sliding of the discharging collecting plate 101, the receiving ladder block 32 is compressed by applying pressure to the receiving ladder block 32. When the spring assembly 31 is compressed, the spring assembly 31 generates a reaction force that is applied to the discharging collecting plate 101 through the receiving ladder block 32, thereby limiting the sliding speed of the discharging collecting plate 101 and improving the stability of the discharging collecting plate 101 during the sliding of the discharging collecting plate 101. The design buffers and limits the sliding speed of the discharging collecting plate 101, thereby improving the stability of the discharging collecting plate 101 during the sliding of the discharging collecting plate 101. Thus, the stability of the detection chip placed on the discharging collecting plate 101 during the sliding of the discharging collecting plate 101 is improved, and the stability of the chip during the discharging is improved. During operation, the condenser 42 is started to run, and the cooling liquid is transported to the pipeline in the cooling pipeline box 4 through the one-side connecting pipe 41. At the same time, the cooling liquid can be circulated and cooled again through the pipeline in the cooling pipeline box 4, thereby improving the overall cooling effect of the cooling pipeline box 4 on the detection chip placed on the upper part of the cooling pipeline box 4, and reducing the change of the magnetic material. The design sets a recyclable cooling liquid device at the lower end of the detection chip, thereby improving the temperature stability during the detection process, reducing the influence of temperature rise on the magnetic material, and improving the accuracy of the detection result. During operation, the detection chip slides into the receiving plate block 5 along the inclination angle and the sliding process of the discharging collecting plate 101, and is received by the cotton strip 51. When the detection chip slides onto the cotton strip 51, the cotton strip 51 buffers the detection chip to stably slide onto the receiving plate block 5, which is convenient for the staff to collect. The design reduces the gravity of the detection chip during the sliding of the detection chip through the cotton strip, reduces the impact on the chip, thereby improving the stability and safety of the collected chip.
[0033] The basic principle, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.
Claims
1. A microelectronic magnetic force automatic detection device, comprising a base plate (1); characterized in that: The end of the bottom plate (1) is fixedly connected with a placing plate (11); the end of the placing plate (11) is fixedly connected with a support frame (12); the end of the support frame (12) is fixedly connected with a first motor (13); the side wall of the placing plate (11) is fixedly connected with a fixed sliding rail frame (14); the inner side wall of the fixed sliding rail frame (14) is fixedly connected with a first motor (13); the output end of the first motor (13) is slidably connected with a telescopic column (15); the end of the telescopic column (15) is fixedly connected with a sliding rail plate (16); the inside of the sliding rail plate (16) is fixedly connected with an air cylinder (17); the end of the air cylinder (17) is fixedly connected with a hollow suction cup (18); the surface of the sliding rail plate (16) is fixedly connected with a positioning concave block (19); the top of the placing plate (11) is provided with a blanking collecting plate (101); the end of the placing plate (11) is fixedly connected with a positioning convex block (102); the surface of the positioning convex block (102) is rotatably connected with a right long rotating rod (103); the right long rotating rod (103) and a right short rotating rod (104) are slidably connected; the right short rotating rod (104) and the blanking collecting plate (101) are rotatably connected; the end of the right long rotating rod (103) is fixedly connected with a connecting rod (105); the end of the connecting rod (105) is fixedly connected with a left long rotating rod (106); the left long rotating rod (106) is rotatably connected with the positioning concave block (19); the left long rotating rod (106) and a left short rotating rod (107) are slidably connected; the left short rotating rod (107) and the blanking collecting plate (101) are rotatably connected; the ends of the blanking collecting plate (101) are provided with a sliding groove (108) on both sides.
2. A microelectronic magnetic force automatic detection device as claimed in claim 1, characterized in that: The end of the bottom plate (1) is fixedly connected with a sliding plate (2); the middle of the sliding plate (2) is fixedly connected with a second motor (21); the output end of the second motor (21) is rotatably connected with a threaded rod (22); the surface of the threaded rod (22) is slidably connected with a sliding block (23); the end of the sliding block (23) is fixedly connected with a display screen (24); the end of the display screen (24) is fixedly connected with a detection needle (25); the ends of the display screen (24) are symmetrically fixedly connected with a plurality of groups of wave-shaped hoses (26); the end of the wave-shaped hose (26) is fixedly connected with a rubber block (28); the inside of the wave-shaped hose (26) is provided with a wave-shaped spring (27); the wave-shaped spring (27) and the rubber block (28) are fixedly connected.
3. The microelectronic magnetic force automatic detection device as described in claim 1, characterized in that: The end of the placing plate (11) is fixedly connected with a positioning groove block (3); the ends of the positioning groove block (3) are fixedly connected with a spring assembly (31); the end of the spring assembly (31) is fixedly connected with a receiving ladder block (32).
4. A microelectronic magnetic force automatic detection device as in claim 1, wherein: The middle of the placing plate (11) is fixedly connected with a cooling pipeline box (4); the ends of the cooling pipeline box (4) are fixedly connected with a connecting pipe (41); the connecting pipe (41) and a condenser (42) are pipeline connected.
5. The microelectronic magnetic force automatic detection device as described in claim 1, characterized in that: The end of the bottom plate (1) is fixedly connected with a receiving plate block (5); the surface of the receiving plate block (5) is linearly arrayed and fixedly connected with cotton strips (51).
6. A microelectronic magnetic force automatic detection device as in claim 3, wherein: The end of the receiving ladder block (32) is fixedly connected with a smooth sheet (6).