JP7840214B2 - Test apparatus and measurement method - Google Patents

Description

This invention relates to a test apparatus and a measurement method.

The three-point bending test, as defined in the SEMI (Semiconductor Equipment and Materials International) standard G36-0303, is widely used as a method for measuring the strength of semiconductor chips, and testing equipment is used to perform this test (see, for example, Patent Document 1).

Japanese Patent Publication No. 2020-094833

The testing apparatus described in Patent Document 1, etc., crushes a semiconductor chip, which serves as the test specimen, by pressing it with an indenter. The testing apparatus is equipped with a load cell that measures the load applied by the indenter to the test specimen, and calculates the flexural strength based on the load value at the time the test specimen is crushed.

Generally, load cells with a higher measurable load capacity have lower load resolution compared to load cells with a lower measurable load capacity. Using a high-load load cell on a test specimen that can be fractured at a low load makes precise measurement difficult. Therefore, we offer separate testing equipment for test specimens that can be fractured at low loads and for test specimens that require high loads for fracture.

However, there is a demand to test both specimens requiring high loads for fracture and specimens that can be fractured with low loads using a single testing device. Changing load cells depending on the specimen being fractured is cumbersome.

The objective of this invention is to provide a testing apparatus and measurement method that enable high-precision measurement regardless of the test specimen.

To solve the above-mentioned problems and achieve the objective, the present invention provides a test apparatus comprising: a support unit having a support portion that supports the lower surface of a test piece; an indenter positioned above the support unit and pressing the test piece supported by the support unit; a moving unit that moves the indenter at a constant velocity from a retracted position where the tip of the indenter does not contact the test piece supported by the support unit toward the test piece supported by the support unit, thereby pressing and destroying the test piece with the indenter; a load cell for measuring the load applied by the indenter to the test piece supported by the support unit; and a controller for controlling at least the moving unit, wherein the movement of the indenter moved by the moving unit The system is characterized by comprising an indenter movement detection unit that detects the amount of movement, a load cell that measures the load applied by the indenter to the test specimen with a predetermined resolution, and a controller that detects contact of the indenter with the test specimen by detecting the load in the load cell as the indenter moves from the retracted position toward the approaching position, and after detecting contact of the indenter with the test specimen, detecting the failure of the test specimen by the load cell's measured value changing from rising to falling, and if the failure of the test specimen is detected within the resolution of the load cell, the load value at the time of failure of the test specimen is calculated by converting the amount of movement of the indenter after the measurement of the load value immediately before the failure of the test specimen was detected into a load value and adding it to the load value immediately before.

In the aforementioned test apparatus, the controller may use the amount of movement of the indenter after the measurement of the load value immediately preceding the detection of fracture of the test specimen as the final movement, and calculate the load value at the time of fracture by adding the load value immediately preceding the detection of fracture to the load value obtained by multiplying the difference between the first load value and the second load value by the ratio of the final movement to the amount of movement of the indenter between the measurement of the first load value and the measurement of the second load value in the load cell before the detection of fracture of the test specimen.

The present invention relates to a measurement method for measuring the strength of a test specimen, which involves moving an indenter at a constant velocity from a retracted position spaced away from the upper surface of the test specimen toward the test specimen, thereby pressing and breaking the test specimen with the indenter. The method is characterized by detecting contact between the indenter and the test specimen by measuring the load applied by the indenter to the test specimen using a load cell while the indenter moves from the retracted position toward the test specimen, detecting the breakage of the test specimen when the load cell reading changes from an upward to a downward value after the contact is detected, and calculating the load value at the time of the test specimen's breakage by converting the amount of movement of the indenter after the measurement of the load value immediately before the breakage was detected into a load value and adding it to the load value immediately before the breakage was detected.

In the above measurement method, the amount of movement of the indenter after the measurement of the load value immediately before the failure of the test specimen is detected may be defined as the final movement. The ratio of the final movement to the amount of movement of the indenter between the measurement of the first load value and the measurement of the second load value in the load cell, before the failure of the test specimen is detected, may be multiplied by the difference between the first and second load values to calculate the load value at the time of failure of the test specimen. This load value may be added to the load value immediately before the failure of the test specimen was detected.

This invention offers the advantage of enabling highly accurate measurements regardless of the test specimen.

Figure 1 is a perspective view showing an example of the configuration of a test apparatus according to Embodiment 1. Figure 2 is a schematic perspective view showing the test specimen to be measured using the test apparatus shown in Figure 1. Figure 3 is a schematic perspective view showing the wafer on which the test specimen shown in Figure 2 is manufactured. Figure 4 is a schematic front view showing the indenter and test specimen in the retracted position of the test apparatus shown in Figure 1. Figure 5 is a schematic front view showing the indenter in contact with the test specimen shown in Figure 4. Figure 6 is a schematic front view showing the fractured state of the test specimen shown in Figure 4. Figure 7 schematically shows the measurement results after the lower end of the indenter of the load cell of the test apparatus shown in Figure 1 comes into contact with the test specimen. Figure 8 schematically shows the measurement results of the load cell and the detection results of the indenter displacement detection unit of the test apparatus shown in Figure 1. Figure 9 is a perspective view of the main parts of an example of the configuration of a test apparatus according to a modified embodiment of Embodiment 1.

The embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to those skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate. In addition, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[Embodiment 1]
A test apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. Figure 1 is a perspective view showing an example of the configuration of the test apparatus according to Embodiment 1. Figure 2 is a schematic perspective view showing a test piece to be measured by the test apparatus shown in Figure 1. Figure 3 is a schematic perspective view showing a wafer on which the test piece shown in Figure 2 is manufactured.

The test apparatus 1 shown in Figure 1, according to Embodiment 1, is a device for measuring the flexural strength σ, which is the strength of the test specimen 200, by destroying the test specimen 200 shown in Figure 2. The test specimen 200 shown in Figure 2 is a so-called semiconductor chip, comprising a substrate 201 and a device 203 formed on the surface 202 of the substrate 201. The test specimen 200 shown in Figure 2 is manufactured by individually dividing it from the wafer 204 shown in Figure 3. Note that the same reference numerals are used to denote the same parts of the test specimen 200 and the wafer 204.

(Wafer)
In Embodiment 1, the wafer 204 is a disc-shaped semiconductor wafer or optical device wafer, etc., with silicon, sapphire, gallium, etc. as the substrate 201. The wafer 204 has devices 203 formed in regions partitioned in a grid pattern by a plurality of division lines 205 formed in a grid pattern on the surface 202 of the substrate 201. In Embodiment 1, the wafer 204 is supported by an annular frame 206 attached to an adhesive tape 207, which has an annular frame 206 attached to its outer edge, and is attached to the back surface 208 (corresponding to the bottom surface) on the back side of the surface 202. The wafer 204 is also divided into individual test pieces 200 along the division lines 205.

In Embodiment 1, the test piece 200 has a device 203 formed on the surface 202 of the substrate 201. However, in the present invention, the device 203 does not necessarily have to be formed on the surface 202.

(Test equipment)
Next, the test apparatus 1 will be described. Figure 4 is a schematic front view showing the indenter and test piece in the retracted position of the test apparatus shown in Figure 1. Figure 5 is a schematic front view showing the state in which the indenter is in contact with the test piece shown in Figure 4. Figure 6 is a schematic front view showing the state in which the test piece shown in Figure 4 has been destroyed. Figure 7 is a schematic diagram showing the measurement results after the lower end of the indenter of the load cell of the test apparatus shown in Figure 1 has come into contact with the test piece. Figure 8 is a schematic diagram showing the measurement results of the load cell and the detection results of the indenter movement detection unit of the test apparatus shown in Figure 1.

As shown in Figure 1, the test apparatus 1 comprises a main body 2, a lower container 3, a support unit 10, a pressing unit 20, a fragment discharge unit 30, an indenter movement detection unit 40, and a control unit 100, which acts as a controller. The lower container 3 is positioned on the main body 2 and is formed in a box shape with an opening 4 on its upper side.

The support unit 10 supports the back surface 208 of the test specimen 200. The support unit 10 is housed within the lower container 3. As shown in Figures 1, 4, 5, and 6, the support unit 10 comprises a pair of elongated support members 11 for supporting the test specimen 200, and a support member movement mechanism 13 (shown only in Figure 1) for changing the position of each elongated support member 11 in the X-axis direction parallel to the horizontal direction, and the distance 12 between the pair of elongated support members 11. The pair of elongated support members 11 are arranged with a predetermined distance 12 between them in the X-axis direction. Each elongated support member 11 has a rectangular parallelepiped support body 14 and a support projection 15 (corresponding to a support) provided on the support body 14.

The support bodies 14 of the pair of elongated support members 11 are arranged with a gap between them in the X-axis direction, and a gap 12 is provided between them. The upper surface of the support body 14 is parallel to the horizontal direction.

The support projections 15 are formed projecting upward from adjacent edges on the upper surfaces of each support body 14. Specifically, a pair of support projections 15 are provided on the support unit 10, and these pairs of support projections 15 are arranged with a predetermined distance L in the X-axis direction. The distance L between the pair of support projections 15 is the distance between the upper ends 151 of the support projections 15. In Embodiment 1, the support projections 15 extend linearly in the Y-axis direction, parallel to the horizontal direction and perpendicular to the X-axis direction, and are arranged along the entire length of the aforementioned edges of the support body 14. The cross-sectional shape of the upper surface of the support projection 15 in the X-axis direction is formed as an upwardly convex curved surface, and this shape is maintained along the entire length in the Y-axis direction. The support projections 15 support the back surface 208 of the test piece 200, with the back surface 208 of the test piece 200 resting on the upper end 151 of the support projection 15.

The support member movement mechanism 13 moves each long support member 11 in the X-axis direction and comprises a ball screw rotatably mounted on a fixing plate 16 fixed to the main body of the device 2, a motor that rotates the ball screw, and guide rails that support each long support member 11 so as to be movable in the X-axis direction.

The pressing unit 20 uses an indenter 24 to press the test piece 200, whose back surface 208 is supported by a pair of support protrusions 15 of the support unit 10, and measures the load applied to the pressing unit 20 when the test piece 200 is pressed, while simultaneously crushing the test piece 200 supported by the support unit 10. The pressing unit 20 is located above the lower container 3.

As shown in Figure 1, the pressing unit 20 comprises a moving unit 21, a moving base 22, an indenter 24, and a load cell 23.

The moving unit 21 moves the indenter 24 relatively close to the test piece 200, whose back surface 208 is supported by a pair of support protrusions 15 of the support unit 10, in the Z-axis direction. The Z-axis direction is perpendicular to the X-axis and Y-axis directions. The moving unit 21 comprises a support plate 211 extending upward from the main body 2 and fixed to the main body 2, a ball screw 212 rotatably supported on the support plate 211 around its axis, a motor 213 that rotates the ball screw 212 around its axis, and a guide rail 214 that supports the moving base 22 so as to be movable in the Z-axis direction.

The longitudinal directions of the support plate 211, ball screw 212, and guide rail 214 are parallel to the Z-axis direction. The ball screw 212 is screwed into a screw hole provided in the movable base 22. The guide rail 214 is attached to the support plate 211. The movable unit 21 moves the indenter 24 in the Z-axis direction via the movable base 22 by rotating the ball screw 212 around its axis using a motor 213.

In Embodiment 1, the moving unit 21 is also a unit that moves the indenter 24 at a constant velocity in the direction approaching the test piece 200 supported by the support unit 10, from a retracted position where the lower end 241, which is the tip of the indenter 24 as shown in Figure 4, does not come into contact with the test piece 200 supported by the support unit 10, thereby pressing and destroying the test piece 200 with the indenter 24. The retracted position is a position where the lower end 241 of the indenter 24 is at a predetermined distance from the upper surface of the test piece 200 supported by the support unit 10.

The movable base 22 is formed in a rectangular parallelepiped shape, with a cylindrical first support member 221 extending downwards connected to its lower surface. A load cell 23 is fixed to the lower end of the first support member 221. The load cell 23 measures the load value (hereinafter referred to as the load value) applied by the indenter 24 to the test piece 200, whose back surface 208 is supported by the support projections 15 of a pair of elongated support members 11 of the support unit 10, and outputs the measurement result to the control unit 100.

The load value measured by the load cell 23 is zero (N) until the indenter 24 makes contact with the test piece 200, which is supported on its back surface 208 by the support projection 15 of the support unit 10, as the pressing unit 20 moves the indenter 24 from its retracted position.

The load value measured by the load cell 23 increases from zero when the indenter 24 comes into contact with the test piece 200, which is supported on its back surface 208 by the support projections 15 of the support unit 10, as shown in Figure 5, as the pressing unit 20 moves the indenter 24 from its retracted position. The load value measured by the load cell 23 gradually increases as the indenter 24 moves further closer to the support unit 10 than the position where it first contacts the test piece 200. The load value measured by the load cell 23 decreases from its maximum value P3 (shown in Figure 7, hereinafter referred to as the load value at failure P3) to zero (N) when the indenter 24 breaks the test piece 200, which is supported on its back surface 208 by the pair of support projections 15 of the support unit 10, as shown in Figure 6. The load value at failure P3 corresponds to the flexural strength σ of the test piece 200.

The horizontal axis in Figure 7 shows the distance (corresponding to the amount of movement) of the indenter 24 after its lower end 241 contacts the test piece 200 supported by the support unit 10. It indicates that the indenter 24 gradually moves closer to the support unit 10 as it moves towards the right end. The vertical axis in Figure 7 shows the load value (N) measured by the load cell 23 after the lower end 241 of the indenter 24 contacts the test piece 200 supported by the support unit 10.

Thus, as shown in Figure 7, the load value measured by the load cell 23 increases proportionally to the distance the indenter 24 moves from the position where the lower end 241 of the indenter 24 contacts the test piece 200 supported by the support unit 10 until the test piece 200 is destroyed. Furthermore, the load value output by the load cell 23 to the control unit 100 is a so-called digital signal with a predetermined number of digits (e.g., 256) consisting of 0s and 1s. Therefore, the load value output by the load cell 23 to the control unit 100 indicates load values at predetermined resolution ΔP (shown in Figures 7 and 8). In other words, the load cell 23 measures the load value at which the indenter 24 presses the test piece 200 with a predetermined resolution ΔP.

In Figure 8, the vertical axis shows the load value (N) measured by the load cell 23 and the distance traveled by the indenter 24 detected by the indenter movement detection unit 40, from the time the lower end 241 of the indenter 24 contacts the test piece 200 supported by the support unit 10. The horizontal axis of Figure 8 shows the elapsed time.

As shown in Figure 1, a clamping member 223 is attached to the lower side of the load cell 23 via a cylindrical second support member 222. The clamping member 223 is formed in a roughly gate-like shape when viewed from the front, and an indenter 24 is fixed between a pair of opposing clamping surfaces 224 to press against the test piece 200, whose back surface 208 is supported by the support projection 15 of the support unit 10.

The indenter 24 is positioned above the distance 12 between the pair of elongated support members 11 of the support unit 10 and at the center of the distance L in the X-axis direction between the upper ends 151 of the support projections 15 of the pair of elongated support members 11. It presses against the test piece 200, whose back surface 208 is supported by the pair of support projections 15 of the support unit 10. The indenter 24 extends parallel to the support projections 15 of the support unit 10 and is formed in a tapered plate shape, becoming narrower towards the bottom, with its lower end formed as a curved surface convex downwards. However, the shape of the indenter 24 is not limited to this in the present invention. The lower end 241 of the indenter 24 is supported by a clamping member 223 parallel to the Y-axis direction, and the lower end 241 is positioned above the center between the pair of support projections 15 of the support unit 10.

Furthermore, a pair of plate-shaped connecting members 225 are attached to both sides of the movable base 22. The connecting members 225 extend downward from the sides of the movable base 22, with their lower ends positioned below the lower ends of the clamping members 223.

Furthermore, as shown in Figure 1, the pressing unit 20 comprises an upper container 25 and an air supply unit 26. The upper container 25 is attached to the lower end of the connecting member 225 and has an opening at the bottom, forming a box shape capable of housing the pair of elongated support members 11 of the support unit 10. The upper container 25 is also positioned below the clamping member 223 and is provided with an indenter insertion hole 251 through which the indenter 24 can pass.

The upper container 25 is made of a transparent material (such as glass or plastic). Furthermore, the upper container 25 is sized to allow it to enter the lower container 3 through the opening 4. Therefore, when the pressing unit 20 is moved downward by the moving unit 21, the upper container 25 is inserted into the lower container 3 and covers the upper side of the support unit 10.

The air supply unit 26 blows air onto the lower end of the indenter 24. The air supply unit 26 includes a nozzle 261 that sprays air toward the indenter 24, and an air supply source 263 that supplies air to the nozzle 261 via an on/off valve 262.

The nozzle 261 is formed in a pipe shape and is passed through the nozzle insertion hole of the upper container 25, with its tip facing the lower end 241 of the indenter 24 inside the upper container 25. The air supply unit 26 blows air from the nozzle 261 onto the lower end of the indenter 24 to remove foreign matter adhering to the lower end 241 of the indenter 24, the upper surface of the support projection 15, etc.

The fragment discharge unit 30 discharges fragments 209 (shown in Figure 6) of the test specimen 200 that are present inside the lower container 3. The fragment discharge unit 30 comprises a fragment discharge passage 311 that constitutes a path for discharging the fragments 209 of the test specimen 200, and a suction source 313 connected to the fragment discharge passage 311 via an on-off valve 312.

The fragment discharge channel 311 has one end connected to a fragment discharge port that penetrates the bottom of the lower container 3, and the other end connected to the suction source 313 via an on/off valve 312.

The fragment discharge unit 30 discharges the fragments 209 outside the lower container 3 when the on/off valve 312 opens and the suction source 313 sucks the fragment discharge passage 311.

The indenter movement detection unit 40 detects the movement distance, which is the amount of movement of the indenter 24, supported by the movement unit 21, from its retracted position in the Z-axis direction. In Embodiment 1, the indenter movement detection unit 40 is a so-called encoder that outputs the movement distance of the indenter 24 to the control unit 100. In Embodiment 1, the movement distance output by the indenter movement detection unit 40 to the control unit 100 is a so-called digital signal with a predetermined number of digits (for example, 256) consisting of 0s and 1s.

In other words, the indenter movement detection unit 40 detects the movement distance of the indenter 24 with a predetermined second resolution Δd. In Embodiment 1, from the moment the lower end 241 of the indenter 24 contacts the test piece 200, the indenter movement detection unit 40 outputs multiple (seven in Embodiment 1) detection results, i.e., movement distances, to the control unit 100 while the load cell 23 outputs the measured load value with a resolution ΔP. For this reason, the second resolution Δd of the movement distance measured by the indenter movement detection unit 40 is finer than the resolution ΔP of the load measured by the load cell 23 from the moment the lower end 241 of the indenter 24 contacts the test piece 200 until the indenter 24 approaches the support unit 10 and presses against the test piece 200.

The control unit 100 controls each of the aforementioned units of the test apparatus 1 to cause the test apparatus 1 to perform test operations on each test piece 200. Specifically, the control unit 100 controls at least the moving unit 21. The control unit 100 is a computer comprising a arithmetic processing unit with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read-only memory) or RAM (random access memory), and an input/output interface device. The arithmetic processing unit of the control unit 100 performs arithmetic processing according to the computer program stored in the storage device and outputs control signals for controlling the test apparatus 1 to each of the aforementioned units of the test apparatus 1 via the input/output interface device.

Furthermore, the control unit 100 is connected to a display unit, which is a display means having a display screen that displays the status of the test operation and images, a touch panel, which is an input means connected to the control unit 100 and used by the operator to input information to the control unit 100 of the test device 1, and a notification unit. In other words, the test device 1 comprises a display unit, a touch panel, and a notification unit.

The display unit consists of a liquid crystal display device and the like. The touch panel is superimposed on the display screen of the display unit. The notification unit includes a patrol light (registered trademark) that emits light to notify the operator, and a speaker that emits sound to notify the operator. The notification unit also displays an image for notification to the operator on the display unit.

Furthermore, as shown in Figure 1, the control unit 100 includes a load value calculation unit 101. The load value calculation unit 101 detects contact between the indenter 24 and the test piece 200 by detecting a load value exceeding zero in the load cell 23 while the indenter 24 moves from its retracted position towards the test piece 200. It also detects the failure of the test piece 200 when the load value measured by the load cell 23 changes from rising to falling after detecting contact between the indenter 24 and the test piece 200. Additionally, if the failure of the test piece 200 is detected within the resolution ΔP of the load cell 23, the load value calculation unit 101 converts the movement distance d2 (shown in Figures 7 and 8) of the indenter 24 after the measurement of the load value P2 (shown in Figures 7 and 8) immediately before the failure of the test piece 200 is detected into a load value, and calculates the load value P3 at the time of failure of the test piece 200 by adding the converted load value to the previous load value P2.

The load value calculation unit 101 acquires the load value measured by the load cell 23 and the amount of movement detected by the indenter movement detection unit 40 while the indenter 24 moves from its retracted position towards the test piece 200, and stores each of them linked to the time they were acquired. When the latest load value measured by the load cell 23 becomes greater than zero, the load value calculation unit 101 detects contact between the indenter 24 and the test piece 200. After detecting contact between the indenter 24 and the test piece 200, if the latest load value measured by the load cell 23 falls below the previous load value, the load value calculation unit 101 detects the failure of the test piece 200.

The load value calculation unit 101, upon detecting the failure of the test piece 200, calculates the movement distance d2 (shown in Figure 7) of the indenter 24 from the time the load value P2 immediately preceding the detection of failure was measured until the failure of the test piece 200 was detected. The load value P2 immediately preceding the failure corresponds to the second load value. The movement distance d2 corresponds to the amount of movement of the indenter 24 after the measurement of the load value P2 immediately preceding the detection of failure of the test piece 200, and the final amount of movement. In Embodiment 1, as shown in Figure 8, it is the difference in movement distance output by the indenter movement detection unit 40 from the time the load value P2 immediately preceding the detection was measured until the failure of the test piece 200 was detected.

The load value calculation unit 101 calculates the travel distance d1 (shown in Figures 7 and 8) of the indenter 24 between the time the immediately preceding load value P2 was measured and the load value P1 (shown in Figure 7) measured immediately before that load value P2. Note that load value P1 corresponds to the first load value. The travel distance d1 corresponds to the amount of movement of the indenter 24 between the measurement of the first load value P1 by the load cell 23 and the measurement of the immediately preceding load value P2, which is the second load value, before detecting the failure of the test piece 200. In Embodiment 1, it is the difference in travel distance output by the indenter movement detection unit 40 between the measurement of the first load value P1 and the measurement of the immediately preceding load value P2.

The load value calculation unit 101 calculates the load value P3 at the time of failure of the test piece 200 using the following formula 1.

The load value calculation unit 101 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1, thereby calculating the ratio of the final amount of movement, which is the movement distance d2, to the movement distance d1, i.e., (d2/d1), and multiplies (d2/d1) by the resolution ΔP (corresponding to the difference between the first load value and the second load value) to convert the movement distance d2 into a load value ((d2/d1) × Δp). The load value calculation unit 101 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1, and adds the converted load value ((d2/d1) × Δp) to the load value P2 immediately before the test piece 200 was destroyed, thereby calculating the load value P3 at the time of failure of the test piece 200. Figure 8 shows a case where the indenter movement detection unit 40 outputs detection results 8 times during a travel distance d1, and 4 times during a travel distance d2.

The control unit 100 calculates the flexural strength σ of the test specimen 200. The control unit 100 calculates the flexural strength σ using the following equation 2, where L (mm) is the distance in the X-axis direction between the upper ends 151 of the pair of support protrusions 15, W (N) is the load value P3 at the time of fracture of the test specimen 200, b is the width of the test specimen 200 in the Y-axis direction, and h (mm) is the thickness of the test specimen 200.

The control unit 100 stores a one-to-one correspondence between the flexural strength σ and information about the test specimen 200 (e.g., ID information).

The load value calculation unit 101 performs calculations according to a computer program stored in a memory device by the arithmetic processing unit.

(Measurement method)
Next, the measurement method according to Embodiment 1 will be described based on the drawings. The measurement method according to Embodiment 1 is a method for calculating the load value P3 at the time of fracture of the test piece 200, and is a method in which the indenter 24 is moved at a constant velocity from a retracted position spaced away from the upper surface of the test piece 200 toward the test piece 200, and the test piece 200 is pressed and fractured with the indenter 24 to measure the flexural strength σ of the test piece 200. The measurement method according to Embodiment 1 is also a test operation of the test apparatus 1.

The test apparatus 1, with the configuration described above, receives and stores test conditions and other information input by an operator, such as by operating the touch panel 120, via the control unit 100. These test conditions include the retracted position, the movement speed of the indenter 24 in the direction approaching the test piece 200 from the retracted position, the thickness h of the test piece 200, the width b of the test piece 200, and the distance L between the upper ends 151 of the pair of support protrusions 15. When the control unit 100 receives an instruction from the operator to start the test operation, the test apparatus 1 begins the test operation, i.e., the measurement method.

In the measurement method, the test apparatus 1 uses a control unit 100 to close the on/off valves 262 and 312, control the moving unit 21 to position the indenter 24 in the retracted position, and control the support member moving mechanism 13 to adjust the position of the pair of long support members 11 in the X-axis direction, while also adjusting the distance 12 between the long support members 11 to satisfy the distance L between the upper ends 151 of the pair of support protrusions 15 specified in the test conditions. In the measurement method, the test apparatus 1 uses a transport unit (not shown) to place the back surface 208 of the test piece 200 onto the pair of support protrusions 15 of the support unit 10.

In Embodiment 1, the measurement method involves the control unit 100 controlling the movement unit 21 of the test apparatus 1, which initiates the movement of the indenter 24 from the retracted position shown in Figure 4 towards the test piece 200, whose back surface 208 is supported by a pair of support protrusions 15 of the support unit 10. As a result, the upper container 25 and the like begin to move towards the test piece 200 together with the indenter 24, entering the lower container 3, and the upper container 25 covers the upper side of the pair of elongated support members 11.

Furthermore, in the measurement method, after the test apparatus 1 begins moving the indenter 24 toward the test piece 200, the load value calculation unit 101 of the control unit 100 detects the contact of the indenter 24 with the test piece 200 as shown in Figure 5 by detecting the load with the load cell 23. In the measurement method, even after the indenter 24 has contacted the test piece 200, the test apparatus 1 continues to move the indenter 24 and other components toward the test piece 200 using the moving unit 21, thereby pressing the test piece 200 with the indenter 24.

As the indenter 24 moves, the load value measured by the load cell 23 increases. During the test operation, the control unit 100 of the test apparatus 1 moves the indenter 24 and other components closer together, further pressing the test piece 200 with the indenter 24, causing the test piece 200 to bend and, as shown in Figure 6, to break the test piece 200. When the test piece 200 is broken, the load value measured by the load cell 23 changes from increasing to decreasing, and the load value calculation unit 101 detects the breakage of the test piece 200.

Upon detecting the fracture of the test specimen 200, the test apparatus 1 has the load value calculation unit 101 of the control unit 100 calculate the load value P3 at the time of fracture of the test specimen 200 using the aforementioned formula 1. The control unit 100 also calculates the flexural strength σ of the fractured test specimen 200 using formula 2. The calculated flexural strength σ and the information of the test specimen 200 are then stored in a one-to-one correspondence, and the measurement method is terminated. In this way, the test apparatus 1 performs a three-point bending test using the pair of support protrusions 15 and the indenter 24 of the test specimen 200, and calculates the flexural strength σ of the test specimen 200 based on this three-point bending test.

As described above, in the measurement method according to Embodiment 1, the load value calculation unit 101 of the control unit 100 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1. The load value is detected by the load cell 23 as the indenter 24 moves from its retracted position toward the test piece 200, thereby detecting contact between the indenter 24 and the test piece 200. Furthermore, after detecting contact between the indenter 24 and the test piece 200, the failure of the test piece 200 is detected when the load value measured by the load cell 23 changes from an upward to a downward shift. In addition, in the measurement method according to Embodiment 1, the load value calculation unit 101 of the control unit 100 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1. When failure of the test piece 200 is detected, the movement distance d2 of the indenter 24 after the measurement of the load value P2 immediately before the failure of the test piece 200 is converted into a load value, and the converted load value is added to the previous load value P2 to calculate the load value P3 at the time of failure of the test piece 200.

Furthermore, in the measurement method according to Embodiment 1, the load value calculation unit 101 of the control unit 100 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1. It then calculates the ratio of the final amount of movement (d2) to the movement distance (d1), i.e., (d2/d1). This (d2/d1) is multiplied by the resolution ΔP (corresponding to the difference between the first load value and the second load value) to convert the movement distance d2 into a load value ((d2/d1) × Δp). In the measurement method according to Embodiment 1, the load value calculation unit 101 of the control unit 100 calculates the load value P3 at the time of failure of the test piece 200 using Equation 1. The converted load value ((d2/d1) × Δp) is then added to the load value P2 immediately before the test piece 200 was failed to calculate the load value P3 at the time of failure of the test piece 200.

When the test piece 200 is pressed by the indenter 24, foreign matter (fragments 209 of the test piece 200, etc.) may adhere to the indenter 24. Since this foreign matter, such as fragments 209, may affect the accuracy of the test, it is preferable to remove it. In Embodiment 1, after the test operation is completed, the test apparatus 1 opens the on-off valve 262 and blows air onto the indenter 24 using the air supply unit 26 to remove the foreign matter adhering to the indenter 24. In this invention, there are no restrictions on the timing of removing foreign matter from the indenter 24, etc., using the air supply unit 26. For example, the removal of foreign matter can be performed as needed between the completion of testing one test piece 200 and the start of testing the next test piece 200.

When the test specimen 200 is tested and foreign matter is removed by the air supply unit 26, fragments 209 of the test specimen 200 accumulate inside the lower container 3. Therefore, in Embodiment 1, the test apparatus 1 uses the fragment discharge unit 30 to collect the fragments 209 accumulated inside the lower container 3. By using the fragment discharge unit 30, the test apparatus 1 can quickly remove the fragments 209 without manually cleaning the inside of the opening 4 of the lower container 3.

The test apparatus 1 and measurement method according to Embodiment 1 described above calculate the load value P3 at the time of test piece 200 failure by converting the movement distance d2 of the indenter 24 from the time the load value P2 immediately before the failure of the test piece 200 is measured until the failure of the test piece 200 is detected into a load value, and adding it to the immediately preceding load value P2. Therefore, the movement distance d2 of the indenter 24 detected by the indenter movement detection unit 40 is converted into a load value less than or equal to the resolution ΔP of the load cell 23. As a result, the test apparatus 1 and measurement method according to Embodiment 1 can calculate the load value P3 at the time of failure with an accuracy less than or equal to the resolution ΔP of the load cell 23, thus enabling highly accurate measurement regardless of the test piece 200.

Furthermore, in the test apparatus 1 and measurement method according to Embodiment 1, the control unit 100 calculates the load value P3 at the time of fracture of the test piece 200 using Equation 1, so the load value P3 at the time of fracture can be calculated with an accuracy of less than or equal to the resolution ΔP of the load cell 23.

[Variation]
A test apparatus according to a modified example of Embodiment 1 of the present invention will be described with reference to the drawings. Figure 9 is a perspective view of the main part of an example configuration of the test apparatus according to a modified example of Embodiment 1. Note that in Figure 9, the same reference numerals are used for the same parts as in Embodiment 1, and their descriptions are omitted.

As shown in Figure 9, the modified test apparatus 1 includes an indenter movement detection unit 40-2, which comprises a linear scale 41 mounted on the support plate 211 and parallel to the Z-axis direction, and a reading head 42 mounted on the movable base 22 that reads the memory of the linear scale 41 and detects the position of the indenter 24 in the Z-axis direction. The indenter movement detection unit 40 outputs the detection result to the control unit 100. In this modified example, the second resolution Δd of the indenter movement detection unit 40-2 is finer than the resolution ΔP of the load cell 23.

In the modified test apparatus 1 of Embodiment 1, the control unit 100 converts the movement distance d2 of the indenter 24 from the time the load value P2 immediately before the failure of the test piece 200 is measured until the failure of the test piece 200 is detected into a load value, and adds it to the immediately preceding load value P2 to calculate the load value P3 at the time of failure of the test piece 200. Therefore, similar to Embodiment 1, the load value P3 at the time of failure can be calculated with an accuracy less than or equal to the resolution ΔP of the load cell 23, enabling highly accurate measurement regardless of the test piece 200.

Furthermore, the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the invention. For example, in the present invention, the indenter movement detection unit 40 may be an encoder for a servo motor 213, which outputs a pulse-like signal to the control unit 100 at predetermined movement distances. In this case, the pulse-like signal output by the indenter movement detection unit 40 to the control unit 100 is output each time the movement distance of the indenter 24 reaches a predetermined second resolution Δd. Even in this case, the second resolution Δd of the movement distance of the indenter movement detection unit 40 is finer than the resolution ΔP of the load of the load cell 23 when the lower end 241 of the indenter 24 contacts the test piece 200 and the indenter 24 approaches the support unit 10 and presses against the test piece 200. Also, in the present invention, the load value P3 at the time of fracture of the test piece 200 can be calculated using Equation 1, and it is not necessary to calculate the flexural strength σ using Equation 2.

1 Test apparatus 10 Support unit 15 Support projection (support part)
21 Mobile unit 23 Load cell 24 Indenter 40, 40-2 Indenter movement detection unit 100 Control unit (controller)
241 Lower end (tip)
200 Test specimens 208 Back side (bottom side)
d2 Travel distance (travel amount, final travel amount)
P1 Load value (first load value)
P2: The load value immediately preceding (the second load value)
P3: Load value at the time of failure; ΔP: Resolution (difference)

Claims (4)

A test apparatus comprising: a support unit having a support portion that supports the lower surface of a test specimen; an indenter positioned above the support unit and pressing the test specimen supported by the support unit; a moving unit that moves the indenter at a constant velocity from a retracted position where the tip of the indenter does not contact the test specimen supported by the support unit, toward the test specimen supported by the support unit, thereby pressing and destroying the test specimen with the indenter; a load cell for measuring the load applied by the indenter to the test specimen supported by the support unit; and at least a controller for controlling the moving unit, wherein
The unit includes an indenter movement detection unit that detects the amount of movement of the indenter moved by the moving unit,
The load cell measures the load applied by the indenter to the test specimen with a predetermined resolution.
The controller detects contact of the indenter with the test specimen by detecting a load in the load cell as the indenter moves from the retracted position toward the test specimen, and after detecting contact of the indenter with the test specimen, detects fracture of the test specimen by the load cell's measurement changing from an upward to a downward.
A testing apparatus that, when fracture of the test specimen is detected within the resolution range of the load cell, calculates the load value at the time of fracture of the test specimen by converting the amount of movement of the indenter after the load value immediately before the fracture of the test specimen is measured into a load value and adding it to the load value immediately before the fracture. The controller is,
The final displacement of the indenter is defined as the amount of movement of the indenter after the load value immediately before the failure of the test specimen is detected has been measured.
The test apparatus according to claim 1, wherein the ratio of the final movement of the indenter to the movement of the indenter between the measurement of a first load value and the measurement of a second load value in the load cell, before detecting the fracture of the test specimen, is multiplied by the difference between the first load value and the second load value to calculate the load value at the time of fracture of the test specimen, by adding the load value obtained by multiplying this ratio by the load value immediately before the fracture of the test specimen is detected. A measurement method for measuring the strength of a test specimen, wherein an indenter is moved at a constant velocity from a retracted position spaced away from the upper surface of the test specimen toward the test specimen, thereby pressing and breaking the test specimen with the indenter,
As the indenter moves from the retracted position towards the test specimen, the load applied by the indenter to the test specimen is measured by a load cell to detect contact between the indenter and the test specimen. After detecting contact between the indenter and the test specimen, the failure of the test specimen is detected when the measured value of the load cell changes from rising to falling.
A measurement method for calculating the load value at the time of fracture of a test specimen by converting the amount of movement of the indenter after the load value immediately preceding the detection of fracture of the test specimen has been measured into a load value, and adding it to the load value immediately preceding the detection. The final displacement of the indenter is defined as the amount of movement of the indenter after the load value immediately before the failure of the test specimen is detected has been measured.
The measurement method according to claim 3, wherein the ratio of the final movement of the indenter to the movement of the indenter between the measurement of a first load value and the measurement of a second load value in the load cell, before detecting the fracture of the test piece, is multiplied by the difference between the first load value and the second load value to calculate the load value at the time of fracture of the test piece by adding the load value obtained by multiplying the difference between the first load value and the second load value to the load value obtained by multiplying the load value obtained by the load value immediately before the fracture of the test piece is detected.