JP2005274217A - Micro-hardness tester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-hardness tester having high resolution and a simple structure. <P>SOLUTION: The reflecting surface of a reflector 12 moving together with an indenter 11 is a curved surface. When the indenter 11 is moved by pressing onto a measuring object 30, a laser beam reflected by the reflecting surface is greatly swung. Hereby, even a slight movement of the indenter 11 can be detected largely. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microhardness meter used for measuring the hardness of a very thin magnetic film or the like, or measuring the hardness of a microscopic region.

In the micro hardness tester, an indenter is pushed into the surface of the object to be measured with a predetermined load, and the hardness of the object to be measured is obtained from the relationship between the load and the amount of pushing (displacement of the indenter).
When measuring the hardness of a very thin film or minute region, or when measuring the hardness of a very soft material, a minute indenter is pushed into the object to be measured with a minute load. Since the indentation load is minute, the displacement of the indenter is very small.
In order to measure the minute displacement of the indenter when it is pushed into the object to be measured, an interference-type laser displacement meter that normally uses the interference between the measurement light and the reference light, or the electrostatic force that accompanies changes in the distance between the electrodes. A capacitance displacement meter using a change in capacitance is used (see Patent Document 1).

JP 2003-130774 A

When measuring the hardness of a film having a thickness of several μm or a minute region having a size of several μm, the displacement of the indenter is on the order of several μm to several hundreds of nm. Further, in order to measure the hardness with such a displacement amount with good reproducibility, a resolution on the order of about one-hundredth of the displacement is required. However, when an interference type laser displacement meter or a capacitance displacement meter is used, it is very difficult to measure such a displacement or to obtain a resolution that is one hundredth of that.
In addition, the interference type laser displacement meter and the capacitance displacement meter have a complicated structure, and there is a problem that the apparatus is expensive.

  The problem to be solved by the present invention is that the hardness of a film having a thickness of about several μm or a region of the same size can be measured with good reproducibility and can be manufactured at a low cost. Is to provide a total.

  In order to solve the above problems, the present invention provides a hardness meter that measures the hardness of a material by pushing the indenter vertically into an object to be measured, and has a reflective surface having a curved surface fixed to the indenter. And a light source for irradiating the reflector with the beam light, and a detector for detecting the position of the beam light reflected by the reflector.

  When measuring the hardness of the object to be measured, the light beam is applied to the reflector while pushing the indenter vertically into the object to be measured. Since the reflector has a curved reflecting surface, when the reflector is displaced by pushing the indenter, the reflection angle of the beam light changes, and the detection position of the beam light in the detector changes greatly. Therefore, a minute displacement of the indenter can be measured with high accuracy. When the curvature of the reflecting surface is increased, the change in the inclination of the reflecting surface with respect to the displacement of the indenter becomes larger, so that the hardness can be measured with higher accuracy.

  As the curved surface shape of the reflecting surface, a cylindrical shape, a spherical shape or the like can be adopted. Moreover, it is good also as a concave surface toward the light source of beam light. The size of the reflector and the curvature of the reflecting surface are appropriately set according to the measurement range (indentation depth range of the indenter) of the micro hardness tester and the desired resolution. When the reflector is enlarged, a large displacement can be dealt with and the measurement range can be expanded. In addition, when a reflective surface having a large curvature is used, the change in the reflection angle of the reflected laser light due to the displacement of the indenter becomes large, and therefore measurement can be performed with higher resolution.

  Since the micro hardness meter according to the present invention detects a slight displacement of the indenter by enlarging the deflection angle of the beam light, the micro hardness can be measured with high accuracy. In addition, since the structure is simple, it can be manufactured at a lower cost than a conventional apparatus using an interference type laser displacement meter or capacitance displacement meter.

  In addition, by increasing the curvature of the reflecting surface of the reflector, the ratio of the change in the reflection angle of the beam light with respect to the change in the indenter pressing amount can be increased, so a highly accurate micro hardness tester can be easily manufactured. can do.

  FIG. 1 is a schematic configuration diagram of a micro hardness tester according to an embodiment of the present invention. The microhardness meter of the present embodiment includes a measuring unit 10 that pushes the indenter 11 into the object to be measured 30, and a control unit 20 that analyzes the amount of pushing of the indenter 11 and controls the operation of the entire apparatus.

  The measuring unit 10 includes an indenter 11, a reflector 12 fixed to the back surface of the indenter 11, a laser light source 13 for irradiating the reflector 12 with a laser beam, a lens 14 for focusing the laser beam reflected by the reflector 12, a reflected laser A detector 15 for detecting the position of the beam is provided. The indenter 11 is fixed to the lower part of the indenter base 17, and the indenter base 17 is moved up and down by an actuator 18. The positions of the laser light source 13, the focusing lens 14, and the detector 15 are fixed with respect to the indenter base 17.

  The indenter base 17 will be described in detail with reference to FIG. The indenter 11 is fixed to the indenter base 17 via a leaf spring 19. Two slits 19a are provided in the longitudinal direction of the center of the leaf spring 19, and the indenter 11 is fixed to the lower part of the center of the elastic part 19b sandwiched between the two slits 19a. A reflector 12 is fixed immediately above the elastic portion 19b to which the indenter 11 is fixed. The upper surface of the reflector 12 is a semi-cylindrical reflecting surface. The indenter base 17 is attached to the actuator 18 in a horizontal state by an arm portion 17a.

  In addition to a mechanism for vertically moving the indenter base 17, the actuator 18 includes a force sensor (load cell) that detects a vertical force applied to the indenter base 17 (not shown). The force applied to the indenter base 17 is the pushing force of the indenter 11 onto the object to be measured 30. This pushing force signal is sent to the control device 21 described later.

  The lens 14 uses a cylindrical lens corresponding to the cylindrical reflecting surface of the reflector 12. The reflecting surface of the reflector 12 may be hemispherical, but in that case, a convex lens is used. If the reflecting surface of the reflector 12 is a concave surface, the lens 14 need not be provided if the laser beam is focused on the detector 15 by the concave mirror.

  In this embodiment, a quadrant photodiode is used as the detector 15. It should be noted that the present invention can be implemented with other photodetectors as long as it can detect a change in the position of the beam light, such as a two-divided photodiode. In order to increase the resolution of the measurement of the displacement of the indenter 11, the detector 15 is desirably installed so that the distance from the reflector 12 is sufficiently long. In a state where the indenter 11 is not subjected to any load, the laser beam emitted from the light source 13, reflected by the reflector 12 and focused by the lens 14, irradiates almost the center of the quadrant photodiode. The positional relationship has been adjusted.

  The control unit 20 controls the movement of the indenter 11, receives a signal related to displacement of the indenter 11 and a signal related to the indentation load from the detector 15 and the actuator 18, and calculates a hardness value, an indenter indentation load, and the like. A personal computer 22 for inputting the measurement conditions and the like and processing data on the calculated hardness value, and a CRT 23 for displaying the measurement conditions and measurement results.

  The procedure of the hardness measurement by the microhardness meter according to the present embodiment is shown. First, the DUT 30 is placed on the sample stage 31 that can move in the xyz direction. Thereafter, the sample stage 31 is moved by the control device 21 so that the target measurement site of the object to be measured 30 is positioned directly below the indenter 11.

  After determining the measurement site, the measurement of hardness is started. First, the indenter base 17 is lowered by the actuator 18 until the indenter 11 contacts the object to be measured 30. Since the positions of the laser light source 13, the lens 14, and the detector 15 are fixed with respect to the indenter base 17, the output of the detector 15 does not change until the indenter 11 comes into contact with the object to be measured 30. However, when the indenter 11 comes into contact with the surface of the device under test 30, the indenter 11 starts to be displaced upward with respect to the indenter base 17 due to the reaction force from the device under test 30. Therefore, the control device 21 detects that the indenter 11 is in contact with the device under test 30 when the reflector 12 starts to be displaced. After this time, the control device 21 changes the indenter descending speed to a low speed and pushes the indenter 11 into the object to be measured 30 until a predetermined load is reached.

  As the indenter 11 comes into contact with the object to be measured 30 and is pushed into the object to be measured 30, the indenter 11 receives a reaction force from the object to be measured 30, and the elastic portion 19b of the leaf spring 19 bends upward. As a result, the reflector 12 moves upward with respect to the indenter base 17, so that the irradiation position of the laser beam on the reflecting surface changes as shown in FIG. In FIG. 3, since the drawing is based on the device under test 30, the indenter 11 and the reflector 12 are drawn so as to move downward. Since the reflecting surface is a curved surface, the change in the irradiation position of the laser beam appears greatly in the change in the direction of the reflected laser beam and is detected by the detector 15 with high resolution. A change in the irradiation position of the laser beam detected by the detector 15, that is, a signal of the indentation depth of the indenter is sent to the control device 21 via the amplifier 16.

  In the control device 21, based on the displacement signal of the indenter 11 sent from the detector 15 and the push load signal of the indenter 11 sent from the actuator 18, for example, as shown in FIG. A graph representing the relationship of (test force) is created, and the hardness of the DUT 30 is determined based on the graph. This is merely an example, and the hardness value may be determined based on other criteria.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the microhardness meter which is one Example of this invention. (A) Front view, (b) Plan view, and (c) Side view of an indenter base. Explanatory drawing showing the state of the displacement of the indenter and the laser beam during the hardness measurement. An example of the graph showing the relationship between the indentation depth and indentation force (test force).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Measuring part 11 ... Indenter 12 ... Reflector 13 ... Laser light source 14 ... Condensing lens 15 ... Detector 17 ... Indenter base 18 ... Actuator 19 ... Leaf spring 19a ... Slit 19b ... Elastic part 20 ... Control part 30 ... Measured object 31 ... Sample stage

Claims (3)

In a hardness meter that measures the hardness of the measured object by pushing the indenter vertically into the measured object,
A reflector having a curved reflecting surface fixed to an indenter, a light source for irradiating the reflector with beam light, and a detector for detecting the position of the beam light reflected by the reflector. A micro hardness tester.   2. The micro hardness tester according to claim 1, wherein the reflecting surface of the reflector is cylindrical.   The microhardness meter according to claim 1 or 2, further comprising an optical element that focuses the beam light reflected by the reflector onto the detector.

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