JP4911113B2 - Height measuring apparatus and height measuring method - Google Patents

Description

  The present invention relates to an apparatus and a method for measuring the height of a surface of an electronic component or the like.

In the field of electronic component mounting, the surface shape of an electronic component is measured using a 3D sensor before the electronic component is mounted on a substrate. The 3D sensor projects a laser beam onto a measurement target such as an electronic component, receives the reflected laser beam on a position detection element called PSD arranged at a predetermined position, and generates an electric signal emitted from the element on which the reflected light is incident. This is a device for measuring the height of a measurement object based on the reference (see Patent Document 1).
JP 2004-235671 A

  When the measurement object by the 3D sensor is an electronic component having a metal electrode, the amount of reflected light incident on the PSD becomes excessive depending on the material and orientation of the electrode, and the charge generated in the received element is saturated. May end up. At this time, the influence may be propagated to the adjacent elements, and it is difficult to accurately measure the shape of the electrode portion due to noise caused by an electric signal emitted from an element that is not actually receiving light.

  An object of the present invention is to provide a height measuring device and a height measuring method that eliminate as much as possible the influence of noise due to excessive light quantity.

The height measuring device according to claim 1 is a laser oscillator that projects laser light in a vertical direction toward an electronic component to be measured, and an angle at which the laser light reflected by the surface of the measurement object is different from the vertical direction. A specific PSD is selected from the plurality of PSDs on the basis of reflection characteristics associated with a plurality of PSDs that respectively receive light at positions that form a specific information of the electronic component to be measured stored in the electronic component information database. A PSD selection unit and means for measuring the height of the measurement object based on an electrical signal emitted from the specific PSD are provided.

  A height measuring apparatus according to a second aspect is the height measuring apparatus according to the first aspect, wherein the reflection characteristic is a reflection direction of the laser light caused by a shape of the electrode.

  A height measuring apparatus according to a third aspect is the height measuring apparatus according to the first aspect, wherein the reflection characteristic is a reflected light amount of laser light caused by a surface state of the electrode.

The height measuring device according to claim 4 is a laser oscillator that projects laser light in a vertical direction toward an electronic component to be measured, and an angle at which the laser light reflected on the surface of the measurement object is different from the vertical direction. A plurality of PSDs that respectively receive light at positions that form a position, and a means for measuring the height of the measurement object based on an electrical signal emitted from a specific PSD that is preselected for each individual measurement object from the plurality of PSDs It was.

According to a fifth aspect of the present invention, there is provided a height measurement method using a plurality of PSDs that respectively receive laser beams reflected from the surface of an electronic component to be measured at positions that form different angles with respect to the vertical direction. A method of measuring the depth, the step of selecting a specific PSD from the plurality of PSDs based on the reflection characteristics associated with the specific information of the electronic component to be measured stored in the electronic component information database ; Measuring a height of a measurement object based on an electrical signal emitted from the selected specific PSD.

By selecting a PSD arranged at a position where the charge of the light receiving element is not saturated based on the reflection characteristics of the electronic component to be measured, an image free from the influence of noise can be generated.

  Embodiments of the present invention will be described with reference to the accompanying drawings. First, the surface shape measuring apparatus will be described with reference to FIGS. FIG. 1 is a block diagram of a surface shape measuring apparatus, and FIG. 2 is a schematic diagram of a 3D sensor. The surface shape measuring apparatus 1 includes a 3D sensor 2, an electronic component information database 3, a PSD selection unit 4, and an image processing unit 5. The 3D sensor 2 includes a laser oscillator 10, 15 degree PSDs 11 and 12, and 35 degree PSDs 13 and 14.

  The 15-degree PSDs 11 and 12 are symmetrically arranged at an angle of 15 degrees with the beam axis 16 of the laser beam projected vertically upward from the laser oscillator 10. Similarly, the 35-degree PSDs 13 and 14 are symmetrically arranged at an angle of 35 degrees with the beam axis 16 of the laser beam. The 15-degree PSDs 11 and 12 and the 35-degree PSDs 13 and 14 receive the laser light 18 diffused and reflected by the electronic component 17 that is the measurement target and collected by the focusing lens 19. The height of the reflection point differs depending on the unevenness of the lower surface (surface on which the electrode is formed) of the electronic component 17, and this appears as a difference in the light receiving position on each PSD 11 to 14.

  Each of the PSDs 11 to 14 generates a charge from the received photoelectric element, and outputs an electrical signal to the image processing unit 5 according to the position of the photoelectric element and the amount of received light. The image processing unit 5 analyzes the electrical signals emitted from the PSDs 11 to 14 and acquires the three-dimensional coordinate value of the reflection point (the XY coordinate value (horizontal coordinate value) of the reflection point is the projection point of the laser beam. Since it is known in advance, what is actually acquired is the Z coordinate value (the coordinate value in the height direction) of the reflection point.) By scanning the lower surface of the electronic component 17 with laser light, the entire three-dimensional coordinate value of the lower surface of the electronic component 17 can be acquired.

  The image processing unit 5 analyzes the three-dimensional coordinate values acquired for the entire lower surface of the electronic component 17 and generates a two-dimensional image representing the surface shape. Here, the surface shape of the lower surface is represented by a gray-scale light / dark distribution by making the color lighter as the Z coordinate value increases and becomes darker.

  Since the PSDs 11 to 14 are arranged away from the light axis 16, the reflected light is not received directly if the shape of the reflection point is horizontal, and diffuse reflected light is received. In general, 15 ° PSDs 11 and 12 having a smaller diffusion angle generate charges larger than 35 ° PSDs 13 and 14. Since the 15 degree PSDs 11 and 12 and the 35 degree PSDs 13 and 14 respectively receive diffuse reflected light with respect to one reflection point, the image processing unit 5 applies two images (one 15 degree PSDs 11 and 12 to one electronic component 17). An image based on the acquired three-dimensional coordinate values and an image based on the three-dimensional coordinate values acquired by the 35-degree PSDs 13 and 14 can be generated.

  The electronic component information database 3 stores the reflection characteristics of the electronic component to be measured. The reflection characteristics stored here are the shape of the electrode that affects the reflection direction of the laser beam and the surface state of the electrode that affects the amount of reflected laser beam. Depending on the direction and amount of reflection of the laser light, the direct reflected light or strong reflected light close to it may be received by the 15 degree PSD 11, 12 or 35 degree PSD 13, 14. Since the reflection characteristics vary depending on the type of electronic component, the electronic component information database 3 stores information relating to these reflection characteristics in association with the unique information of the electronic component, and is related to the unique information of the electronic component to be measured. Information about reflection characteristics can be read out.

  The PSD selection unit 4 selects either 15 degree PSD 11 or 12 or 35 degree PSD 13 or 14 based on the reflection characteristic read from the electronic component information database 3. The image processing unit 5 performs image processing based on the selection result by the PSD selection unit 4, and when the PSD selection unit 4 selects 15 degree PSDs 11 and 12, based on the three-dimensional coordinate values acquired by the 15 degree PSDs 11 and 12. When a surface shape image is generated and 35-degree PSDs 13 and 14 are selected, an image of the surface shape is generated based on the three-dimensional coordinate values acquired by the 35-degree PSDs 13 and 14.

  Next, a processing flow executed by the PSD selection unit will be described with reference to FIGS. 3 is a process flow diagram executed by the PSD selection unit, FIG. 4 is a process flow diagram executed by the PSD selection unit, and FIG. 5 is a schematic diagram showing the shape of the electrodes of the electronic component.

  There are two types of processing flows executed by the PSD selection unit 4. One is a processing flow when the shape of the electrode is used as the reflection characteristic shown in FIG. 3, and the other is the surface state of the electrode shown in FIG. It is a processing flow in the case. As shown in FIG. 5, when the lead 20, which is an electrode of an electronic component, is attached at an angle α with respect to the horizontal direction, the laser light is reflected in a direction that forms an angle 2α with respect to the beam axis 16. Since the PSD is arranged at positions of 15 degrees and 35 degrees with respect to the light axis 16, when the angle 2α is the same as or very close to either 15 degrees or 35 degrees, the PSD receives the reflected light directly. become. The directly reflected light has very large energy, and the element that receives the light becomes saturated in electric charge, and the influence may propagate to adjacent elements.

  In FIG. 3, the PSD selection unit 4 compares the mounting angle α of the lead 20 and the PSD arrangement angle (ST1), and selects a 35 ° PSD that does not directly receive reflected light when α≈7.5 °. (ST2). On the other hand, when α≈17.5 degrees, a 15-degree PSD that does not directly receive reflected light is selected (ST3). Further, when neither PSD receives the reflected light directly, a 15 degree PSD capable of generating a larger charge (that is, having a large S / N ratio) is selected.

  The reflectivity of the electrode varies depending on the material of the surface state, the accuracy of the surface finish, and the like. In the case of an electrode having a high reflectivity, the 15 degree PSD may saturate the electric charge, so the 35 degree PSD having a smaller S / N ratio is more advantageous. The PSD selection unit 4 compares the reflectance of the electrode of the electronic component to be measured in FIG. 4 with a predetermined specified value (ST1), and if it exceeds the specified value, selects the 35 degree PSD (see FIG. 4). ST2). If the specified value is not exceeded, 15 degree PSD is selected (ST3).

  The image processing unit 5 determines the surface shape based on a three-dimensional coordinate value acquired from any one of 15 degrees PSD11, 12 or 35 degrees PSD13, 14 selected by the PSD selection unit 4 based on the reflection characteristics of the electrodes. Therefore, the number of data to be processed is reduced, and the time required for image generation can be shortened.

  Note that the correspondence between the individual information of the electronic component and the PSD of 15 degrees PSD11, 12 or 35 degrees PSD13, 14 is stored in advance in the electronic component information database 3, and from the individual information of the electronic component to be measured. Any PSD may be selected uniquely. The correspondence between the two may be determined in advance, or the actual processing results in the PSD selection unit 4 may be associated with the individual information and made into a database.

  In addition, the height measuring device of the present invention is suitable for measuring the shape of the lower surface (electrode forming surface) of the electronic component described above, but in addition, it is possible to measure the height at a specific position pinpoint. It is.

  The present invention is particularly useful in the field of measuring the shape of the electrode forming surface of an electronic component.

The block diagram of the surface shape measuring apparatus of embodiment of this invention Schematic diagram of 3D sensor according to an embodiment of the present invention Process flow diagram executed by PSD selection unit according to the embodiment of the present invention Process flow diagram executed by PSD selection unit according to the embodiment of the present invention The schematic diagram which shows the shape of the electrode of the electronic component of embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface shape measuring apparatus 2 3D sensor 4 PSD selection part 5 Image processing part 10 Laser oscillator 11, 12 15 degree | times PSD
13, 14 35 degree PSD

Claims (5)

A laser oscillator that projects laser light in a vertical direction toward an electronic component to be measured;
A plurality of PSDs respectively receiving laser beams reflected from the surface of the measurement object at positions at different angles with respect to the vertical direction;
A PSD selection unit that selects a specific PSD from the plurality of PSDs based on the reflection characteristics associated with the unique information of the electronic component to be measured stored in the electronic component information database ;
A height measuring device comprising means for measuring the height of a measurement object based on an electrical signal emitted from the specific PSD.   The height measurement apparatus according to claim 1, wherein the reflection characteristic is a reflection direction of laser light caused by an electrode shape.   The height measuring apparatus according to claim 1, wherein the reflection characteristic is a reflected light amount of laser light caused by a surface state of the electrode. A laser oscillator that projects laser light in a vertical direction toward an electronic component to be measured;
A plurality of PSDs respectively receiving laser beams reflected from the surface of the measurement object at positions at different angles with respect to the vertical direction;
A height measuring device comprising means for measuring the height of a measurement object based on an electrical signal emitted from a specific PSD preselected for each individual to be measured from the plurality of PSDs. A method of measuring the height of a measurement object using a plurality of PSDs that respectively receive laser light reflected from the surface of an electronic component to be measured at positions that form different angles with respect to the vertical direction,
A step of selecting a specific PSD from the plurality of PSDs based on the reflection characteristics associated with the specific information of the electronic component to be measured stored in the electronic component information database, and the emitted from the selected specific PSD A height measurement method including a step of measuring the height of a measurement object based on the electrical signal.

Images