JP2009156672A - Moire type heat distortion measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense with such a pretreatment as coating of paint and the like for a measurement object with black or mirror surface in a moire type heat distortion measuring device. <P>SOLUTION: Desired temperature change is given to a measurement object 6 in a thermostatic chamber 2 and the heat distortion of the measurement object caused by the temperature change is to be measured by a moire sensor 3 through a transparent plate 12 at a window part 11 of the thermostatic chamber in a moire type heat distortion measuring device 1. The moire sensor comprises: a grid 15 where predetermined grid pattern is formed; an illuminating system 16 causing generation of the distortion grid pattern on the measurement object by irradiating illumination light to the measurement object through the grid; and a photographing system 17 obtaining images containing the moire pattern by photographing the distortion grid pattern in the measurement object through the grid. Parallel light beam is used as illumination light of the illumination system. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a moire-type thermal deformation measuring apparatus that measures thermal deformation of a measurement object under a state where a desired temperature change is applied by a moire method, particularly when the measurement object is an electronic component or a substrate. The present invention relates to a suitable moire type thermal deformation measuring apparatus.

  A semiconductor structure electronic component, in particular, a surface mount type electronic component using various package methods such as BGA, SOP, and QFP has a problem of thermal deformation.

  A surface-mount type electronic component has a planar contact with each land of a land group provided on a substrate so that each terminal of the terminal group provided on the back surface or side surface of the package corresponds to that. Mounting on the board is performed by joining by soldering. In such surface mounting, flatness (coplanarity) in the terminal group of the electronic component is important, and if the flatness of the terminal group is not more than a certain level, a terminal having insufficient bonding to the land is generated.

  Such flatness problems are greatly affected by thermal deformation of electronic components. In other words, it is inevitable that electronic components are exposed to various temperature environments, and as a result, a large temperature change causes thermal deformation in a state where the package warps convex or concave. This impairs the flatness of the terminal group, which causes a thermal deformation problem for the electronic component.

  The above-described thermal deformation problem can be applied to the substrate. In other words, the flatness of the land group affects the bonding of the terminals of the electronic component and the land of the board in the same manner as in the case of the terminal group, and the thermal deformation of the board greatly affects the flatness of the land group.

  Due to the thermal deformation problem as described above, for electronic components and substrates, thermal deformation measurement is performed under a condition in which a desired temperature change is given in order to evaluate thermal deformation. In general, a laser method or a moire method is used for thermal deformation measurement of an electronic component or a substrate.

  In the laser method, a measurement object is irradiated with laser light and reflected, and the shape of the measurement object is measured based on the irradiation and reflection of the laser light. An example disclosed in Patent Document 1 is known as a laser thermal deformation measuring apparatus using such a laser system. The laser-type thermal deformation measuring apparatus of Patent Document 1 includes a thermostatic chamber (a thermostatic chamber) and a laser-type displacement meter. The thermostatic chamber is configured to be able to give a desired temperature change to an electronic component or a substrate that is a measurement object placed in the thermostatic chamber, and a window portion in which a transparent plate is assembled is provided on one side surface. . The displacement meter is adapted to irradiate the measurement object in the thermostatic chamber through the window of the thermostatic chamber and to receive the reflected laser light from the measurement target, and based on the irradiation and reflection of the laser light The thermal deformation due to the temperature change of the measurement object is measured.

  Such a laser-type thermal deformation measuring apparatus enables extremely high measurement accuracy but requires a long time for measurement. For this reason, it is particularly useful when measurement with a certain degree of accuracy is required.

  In the moire method, the illumination object is irradiated with illumination light through a grating on which a predetermined grating pattern is formed, and a deformed grating pattern corresponding to the shape of the object to be measured is then used as a shadow of the grating pattern. While being generated on the surface, the deformation grid pattern on the measurement object is imaged through the grid by the imaging system. As a result, a moire fringe image including a moire fringe by the lattice pattern and the deformed lattice pattern can be acquired, and the shape of the measurement object is measured based on the moire fringe image (for example, Patent Document 2). A moire type thermal deformation measuring apparatus using such a moire method uses a constant temperature chamber to give a desired temperature change to an electronic component or substrate as a measurement object, as in the case of a laser type thermal deformation measuring apparatus. It is common.

  That is, the moire type thermal deformation measuring apparatus includes a constant temperature chamber and a moire sensor. The constant temperature chamber is configured to be able to give a desired temperature change to the measurement object placed therein, and is provided with a window portion assembled with a transparent plate on one side surface. On the other hand, the moiré sensor irradiates the measurement object with illumination light through a grating on which a predetermined grating pattern is formed, thereby forming a deformed grating pattern corresponding to the shape of the measurement object on the surface of the measurement object as a shadow of the grating pattern. The illumination system to be generated and the imaging system for obtaining an image including a moire fringe by the lattice pattern and the deformed lattice pattern by capturing an image of the deformed lattice pattern on the measurement object through the lattice.

  Such a moire-type thermal deformation measuring apparatus enables quick measurement, and also provides sufficient accuracy as long as it is normally required, and is highly versatile.

JP-A-8-233543 JP 2007-57313 A

  In the conventional moire type thermal deformation measuring apparatus, it is difficult to measure a measurement target object whose surface is black or mirrored. However, many electronic components and substrates have a black or mirror surface. For this reason, in the conventional moire type thermal deformation measuring device, preprocessing for enabling measurement by applying a paint such as a white paint to the measurement object for many cases where electronic parts and substrates are used as the measurement object. Was necessary. And that caused some disadvantages. For example, it is disadvantageous in that the measurement accuracy is lowered by the applied paint, and it becomes difficult to use the electronic component or the substrate subjected to the thermal deformation measurement for other tests.

  For these reasons, it is desired to enable measurement without pretreatment such as coating of an electronic component or substrate having a black or mirror surface. The present invention has been made to respond to this, and therefore the problem is that a moire-type thermal deformation measuring device does not require pretreatment such as coating of a measurement object having a black or mirror surface. Is to be able to.

  The inventors of the present invention have studied the cause of the measurement difficulty problem that makes it difficult to measure a measurement object having a black or mirror surface on the conventional moire type thermal deformation measuring apparatus. As a result, it has been found that there is a cause in the optical system of the moire sensor, particularly in the illumination system. That is, the conventional moire sensor uses divergent light as illumination light for the illumination system. For this reason, a measurement object having a black surface or a mirror surface cannot generate a sufficient deformed lattice pattern, and therefore, effective moire fringes cannot be generated, resulting in thermal deformation. It becomes difficult to measure.

  From this, it can be said that the measurement difficulty problem can be effectively solved by using parallel light as illumination light of the illumination system.

  The present invention is based on the above-described knowledge, and gives a desired temperature change to the measurement object in a constant temperature chamber provided with a window portion assembled with a transparent plate, and heat of the measurement object due to the temperature change. The moire sensor measures the deformation through the window, and the moire sensor irradiates the object to be measured with illumination light through a grating on which a predetermined grating pattern is formed and the grating. As an illumination system for generating a deformed grid pattern on the surface of the measurement object according to the shape of the measurement object, and imaging the deformed grid pattern in the measurement object through the grating, the grid pattern and the In the moire type thermal deformation measuring apparatus having an imaging system for obtaining an image including moire fringes by a deformed lattice pattern, as the illumination light It is characterized in that the line beam is used.

  As described above, when parallel light is used as illumination light, the illumination system and the imaging system are optically symmetrically arranged with respect to the grating, that is, the optical axes of the illumination system and the imaging system are at the same angle with respect to the perpendicular to the grating. In this way, it is preferable to dispose the illumination system and the imaging system. By doing so, moire fringes can be generated more effectively.

  In the moire type thermal deformation measuring apparatus as described above, a transparent plate of a constant temperature chamber is interposed between the illumination system and the measurement object. Therefore, the reflection of the illumination light by the transparent plate may affect the moire fringe image (image including moire fringes), which may reduce the measurement accuracy. Therefore, it is preferable that the reflected light from the transparent plate does not adversely affect the measurement accuracy.

  In order to prevent the influence of the reflected light by the transparent plate, an antireflection film method and a transparent plate tilt method are possible. The antireflection film system is a system in which an antireflection film is formed on a transparent plate to reduce reflected light, and thereby the influence of reflected light can be suppressed. However, the anti-reflection coating method has a problem of durability of the anti-reflection coating and also has a problem that it is not effective for reflection from the back surface of the transparent plate. On the other hand, the transparent plate tilt method is a method of tilting the transparent plate with respect to the grid, that is, a method of tilting the transparent plate with respect to the perpendicular to the grid, thereby preventing regular reflection illumination light from the transparent plate from entering the imaging system. . Such a transparent plate tilting method can be effectively set by setting an appropriate tilt angle on the transparent plate to effectively prevent the influence of reflected light from the transparent plate.

  For this reason, in the present invention, in the moiré-type thermal deformation measuring apparatus as described above, the transparent plate is controlled by the aperture stop in the imaging system so that the reflected light from the regular reflection of the illumination light is reflected by the transparent plate. It is preferable that the inclined range is inclined with respect to the perpendicular at an angle that can avoid entering the imaging lens.

  According to the present invention as described above, it becomes possible to measure thermal deformation without performing pretreatment such as application of a paint even on an object to be measured having a black or mirror surface. The functionality of the deformation measuring device can be further increased.

  Hereinafter, modes for carrying out the present invention will be described. FIG. 1 schematically shows a configuration of a moire type thermal deformation measuring apparatus 1 according to an embodiment. The moire type thermal deformation measuring apparatus 1 of the present embodiment includes a constant temperature chamber 2, a moire sensor 3, and a control / analyzer 4.

  The constant temperature chamber 2 is configured to be able to give a desired temperature change to the measurement object 6 by maintaining a temperature arbitrarily set within a certain temperature range. The constant temperature chamber 2 having such a function has an outer frame formed by a frame 5 having a sealed structure, and a mounting table 7 for placing a measurement object 6 therein is provided.

  The frame 5 is formed in a structure in which a lower frame 8 and an upper frame 9 are combined by bolting with bolts 10, and a window portion 11 is provided in the upper frame 9. The window portion 11 is formed by assembling the transparent plate 12 in a state inclined at a predetermined angle so that the measurement object 6 can be illuminated and imaged by the moire sensor 3 through the transparent plate 12.

  The mounting table 7 also serves as a heat source function. The mounting table 7 serving as a heat source function is configured to be able to heat or cool the measurement object 6, and heats or cools the measurement object 6 placed on the measurement object 6 to a desired target temperature. It can be heated or cooled to the same temperature as the target temperature of the measuring object 6. The heating heat source in the mounting table 7 is formed with an electric heating structure, while the cooling heat source circulates a cooling medium supplied from a cooling medium supply source (not shown) through the supply pipe 13 to the mounting table 7. It is formed to get in

  The constant temperature chamber 2 as described above can be moved for scanning in the Y direction (the direction perpendicular to the paper surface) with respect to the measurement object 6 of the moire sensor 3. Specifically, the Y-axis stage 14 supports the Y-axis stage 14 so that the Y-axis stage 14 can move in a direction perpendicular to the paper surface.

  The moire sensor 3 has a structure in which the grating 15, the illumination system 16, and the imaging system 17 are unitized and housed in a housing 18, and the optical system has a configuration as shown in FIG.

  The lattice 15 is formed in a flat plate shape and is provided with a predetermined lattice pattern. As the lattice pattern, a linear lattice pattern is usually used, and this embodiment also does so. The lattice 15 can be moved in the vertical direction in the state shown in the figure by a moving mechanism (not shown). This is because the phase shift method can be used as necessary. The phase shift method is one method in the moire method. By using this method, the resolution in the height direction can be increased, and measurement with higher accuracy is possible.

  As shown in FIG. 2, the illumination system 16 converts the divergent light emitted from the light source 21 into parallel light using a parallel light conversion lens 22 to obtain illumination light 23 by parallel light. The illumination system 16 irradiates the measurement object 6 with illumination light 23 through the grating 15, and thereby forms a deformed lattice pattern corresponding to the shape of the measurement object 6 as a shadow of the grating pattern on the grating 15. To cause.

  As shown in FIG. 2, the imaging system 17 includes an imaging lens 24, an aperture stop 25, and an image sensor 26, and image light 27 obtained by illuminating the measurement target 6 with illumination light 23 is generated by the aperture stop 25. An image is obtained by forming an image on the imaging surface of the imaging element 26 by the imaging lens 24 within the limited range. The imaging system 17 is arranged so as to be optically symmetric with respect to the illumination system 16 with respect to the grating 15. That is, the imaging system 17 is arranged such that the angle formed by the optical axis 17 a with respect to the perpendicular V with respect to the grating 15 is the same as the angle between the optical axis 16 a of the illumination system 16 and the perpendicular V. In addition, the imaging system 17 is configured to image the measurement object 6 through the grid 15 in such an arrangement. Therefore, the image pickup device 26 in the image pickup system 17 obtains an image including moire fringes caused by interference between the deformed lattice pattern formed on the surface of the measurement object 6 and the lattice pattern in the lattice 15.

  Such a moire sensor 3 can move for scanning in the X direction (the direction indicated by the arrow X) with respect to the measurement object 6. Specifically, it is supported by an X-axis stage 28 and can be moved in the direction of arrow X by this X-axis stage 28.

  Here, the relationship between the optical system of the transparent plate 12 and the moire sensor 3 in the constant temperature chamber 2 will be described. As described above, the transparent plate 12 is inclined at a predetermined angle. The inclination angle is an angle α shown in FIG. 2 and is an angle of inclination of the transparent plate 12 with respect to the grating 15. This is drawn in the symmetrical arrangement direction of the imaging system 17 and the illumination system 16 so as to be orthogonal to the perpendicular V of the grating 15 (which is also the reference line in the symmetrical arrangement of the illumination system 16 and the imaging system 17 as described above). In other words, the angle of inclination of the transparent plate 12 with respect to the line segment L can be said.

  The reason why the transparent plate 12 is tilted in this way is that the transparent plate reflected light generated by the regular reflection of the illumination light 23 by the transparent plate 12 is effectively incident on the imaging lens 24 in the range restricted by the aperture stop 25. This is in order to be able to avoid it, that is, to make it possible to effectively limit the incidence of light reflected on the transparent plate. Therefore, the angle α is set as an angle necessary for making the above-described incident restriction according to the configuration of the optical system in the moire sensor 3. Such an angle α can be easily obtained by experimenting with an actual optical system. Note that the angle α is preferably set to the minimum necessary for limiting incidence. This is because the internal space of the constant temperature chamber 2 is limited as the angle α increases.

  The control / analysis apparatus 4 is configured by using a general computer system, and controls the illumination system 16 and the imaging system 17 in the moire sensor 3 by a program installed therein, and is obtained by the moire sensor 3. Moire fringe images (images including moire fringes) are analyzed for measurement of thermal deformation of the measurement object 6, and the results are output in an appropriate data format. A known method can be used for the function of the control / analysis device 4.

  Below, the example of the thermal deformation measurement by the above moire type thermal deformation measuring apparatuses 1 is demonstrated. However, it is assumed that the measurement object 6 is an electronic component of a BGA package and the thermal deformation due to temperature change due to heating is measured. In order to perform thermal deformation measurement, first, the upper frame 9 of the constant temperature chamber 2 is removed, and the measurement object 6, that is, the electronic component 6 is placed on the mounting table 7.

  Then, after returning the upper frame body 9, the electronic component 6 is heated to a target temperature (for example, a temperature about the soldering temperature when mounting the electronic component) by the heat source function of the mounting table 7, and at the same time, the inside of the frame body 5 is heated inside the electronic component 6. Heat to the same temperature as the target temperature. As a result, the electronic component 6 undergoes thermal deformation in a state exaggerated in FIG. 3 as an example, and the flatness of the terminal group Tg in the electronic component 6 changes accordingly.

  The temperature of the constant temperature chamber 2 is monitored by the control / analysis device 4. When the target temperature is reached, the measurement object 6 is illuminated and imaged by the moire sensor 3 under the control of the control / analysis device 4. This illumination / imaging process is performed while repeating the above-described scanning of the measurement object 6 of the moire sensor 3 as necessary. Here, the case where scanning is required is a case where the irradiation field of the illumination light by the illumination system 16 is smaller than the size of the measurement object 6.

  In imaging the measurement object 6 by the moire sensor 3, a moire fringe image is obtained and sent to the control / analysis device 4. Then, the control / analysis device 4 analyzes the moire fringe image, and outputs the thermal deformation measurement result of the measurement object obtained in the appropriate data form.

  The moire type thermal deformation measuring apparatus 1 as described above uses parallel light as illumination light in the moire sensor 3. For this reason, even if the surface of the measuring object 6 is black or a mirror surface, a sufficient deformed lattice pattern can be generated on the measuring object 6 as it is, and therefore effective moire fringes can be generated. That is, even for a measurement object whose surface is black or mirrored, it is possible to perform thermal deformation measurement as it is without requiring pretreatment such as application of paint. In the moiré type thermal deformation measuring apparatus 1, the illumination system 16 and the imaging system 17 in the moiré sensor 3 are arranged symmetrically. For this reason, moire fringes can be generated more effectively and measurement with higher accuracy is possible.

  As mentioned above, although the form for implementing this invention was demonstrated, this is only a typical example, This invention can be implemented with a various form in the range which does not deviate from the meaning.

It is a figure which shows typically the structure of the moire type thermal deformation measuring apparatus by one Embodiment. It is a figure which shows the structure of the optical system of a moire sensor. It is a figure which exaggerates and shows the example of the thermal deformation which arises in an electronic component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Moire type thermal deformation measuring apparatus 2 Constant temperature chamber 3 Moire sensor 6 Measurement object 10 Window part 12 Transparent plate 15 Grating 16 Illumination system 16a Optical axis of illumination system 17 Imaging system 17a Optical axis of imaging system 23 Illumination light 24 Imaging lens 25 Aperture Aperture V Perpendicular

Claims (3)

A desired temperature change is given to a measurement object in a constant temperature chamber provided with a window part with a transparent plate, and thermal deformation of the measurement object due to the temperature change is measured through the window part by a moire sensor. The moire sensor irradiates the object to be measured with illumination light through a grating on which a predetermined grating pattern is formed, and forms a deformed grating pattern according to the shape of the object to be measured as a shadow of the grating pattern. An illumination system that is generated on the surface of the measurement object, and an imaging system that obtains an image including the moire fringes by the lattice pattern and the deformed grating pattern by imaging the deformed grating pattern in the measurement object through the grating. In the moire type thermal deformation measuring device that has,
A moiré-type thermal deformation measuring apparatus, wherein parallel light is used as the illumination light.   The moire type thermal deformation measuring apparatus according to claim 1, wherein the illumination system and the imaging system are arranged such that respective optical axes form the same angle with respect to a perpendicular to the grating.   The transparent plate has an angle at which the transparent plate reflected light generated by regular reflection of the illumination light by the transparent plate can be prevented from entering the imaging lens with respect to a range restricted by the aperture stop in the imaging system. The moiré type thermal deformation measuring device according to claim 1, wherein the moiré type thermal deformation measuring device is inclined with respect to the surface.

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