JP5021412B2 - BGA solder ball height measuring device - Google Patents

Description

  The present invention relates to an apparatus for measuring the height of a BGA solder ball, and more particularly to an apparatus for measuring the height of a BGA solder ball using a laser beam.

  Conventionally, a laser beam is irradiated toward a measurement object, and reflected light from the measurement object is received by an image sensor, and the measurement object is based on a detection signal (light reception signal) output from the image sensor. There is provided a displacement sensor for measuring the displacement according to the above. For example, in Patent Document 1 below, a measurement object is irradiated with light from a light source, the reflected light is received by an image sensor, and the measurement object is received from the light source and the image sensor based on the light reception position of the reflected light in the image sensor. Displacement sensors that measure the distance to are disclosed.

Such a displacement sensor measures the displacement or height of the height of a BGA solder ball 31 as a measurement object on a BGA (Ball Grid Array) substrate W as shown in FIG. Used to detect height defects. Here, the BGA solder balls 31 have a pitch P1 in the column direction and a pitch P2 in the row direction, and are arranged in a matrix. At that time, as shown in FIG. 5, the laser beam of the conventional solder ball height measuring device is usually arranged so that a small circular irradiation spot S is formed near the vertex of the BGA solder ball 31. (See R1 row L1 column). Next, for example, the BGA substrate W or the same measuring device is relatively moved (scanned) in the column direction M to measure the BGA solder balls 31 positioned in the R2 row and the L1 column, and then the L2 column to the L4 column. Measurements up to are sequentially performed.
JP 2007-121175 A

  By the way, the BGA solder balls 31 formed on the BGA substrate W are moved from the normal position to the measurement moving direction (column direction) M like the L4 rows of BGA solder balls 31A surrounded by the one-dot chain line in FIG. There may be a positional shift in the orthogonal direction. The displacement of the height of the BGA solder balls 31 arranged in a matrix including the BGA solder balls 31A having such misalignment (hereinafter referred to as “misaligned BGA solder balls”) is converted into the conventional solder as described above. When attempting to measure using a ball height measuring device, the following problems occur.

  That is, when measuring the misaligned BGA solder ball 31A, due to the misalignment, the irradiation spot S of the laser beam is not properly irradiated to the apex of the misaligned BGA solder ball 31A, and the height of the BGA solder ball 31A is high. In some cases, the displacement measurement is not suitably performed. Therefore, in order to reliably measure such a misaligned BGA solder ball 31A, it is necessary to measure the misaligned BGA solder ball 31A again after adjusting the position of the BGA substrate W or the measuring device. Therefore, there is a problem that extra time is required for the measurement work and work efficiency is lowered.

  The present invention has been completed based on the above situation, and the height of the BGA solder ball for improving the working efficiency of the measurement related to the height of the BGA solder balls arranged in a row on the substrate. An object of the present invention is to provide a measuring device.

As a means for achieving the above object, a BGA solder ball height measuring device according to the present invention is a device for measuring the height of each of a plurality of BGA solder balls arranged in a row on a substrate. And a light projecting means for irradiating the plurality of BGA solder balls with light and a light receiving surface comprising a plurality of pixels, and the reflected light from the light irradiated BGA solder balls is transmitted from the BGA solder balls. A linear image sensor that receives light at a position on the light receiving surface according to the distance of the light and generates a light reception signal according to the light receiving position, and a displacement of the height of the BGA solder ball based on the light reception signal of the linear image sensor. In the apparatus comprising the measuring means for measuring, the light emitted from the light projecting means is wide in the width direction of the linear image sensor and in a direction orthogonal to the direction of the row. The light projecting means is formed to have a pot, and the light projecting means moves relative to each of the plurality of BGA solder balls along the row direction with respect to each of the plurality of BGA solder balls. The length of the wide spot in the longitudinal direction is sequentially irradiated with light having various spots, and the length in the longitudinal direction of the wide spot is at least twice as large as the positional deviation dimension of the BGA solder ball allowed in the direction orthogonal to the direction of the row. Features.

  According to this configuration, the light emitted from the light projecting means is in a direction orthogonal to the direction of the plurality of BGA solder balls arranged in a row on the substrate and in the width direction of the linear image sensor. It is formed so as to have a wide spot. Therefore, when measuring the displacement of the height of BGA solder balls arranged in a matrix on the BGA substrate, for example, some of the BGA solder balls are arranged so as to be shifted in a direction orthogonal to the direction of the column to be measured. Even so, by appropriately setting the dimension in the longitudinal direction of the spot in relation to the positional deviation, the displacement measurement of the height of the BGA solder ball which has been displaced can be performed in a single measurement. That is, in order to reliably measure such a misaligned BGA solder ball, it is not necessary to adjust the position of the BGA substrate or the measuring apparatus and perform measurement related to the misaligned BGA solder ball again. As a result, it is possible to improve the working efficiency of the measurement related to the height of the BGA solder balls arranged in rows on the substrate.

  Here, the meaning of “wide spot” means a cross section of light having a shape whose dimension in the direction perpendicular to the row direction of the BGA solder balls is longer than that in the row direction. Shapes, flat circles, flat ellipses, etc. Further, the meaning of “height measurement” includes measuring a displacement from a reference height and determining the height using the displacement.

  The peculiarity of the present invention is that a wide irradiation spot (or a linear irradiation spot) is originally used for detecting the flatness of a flat surface when the object to be measured has a plate shape. However, it is the point of finding the applicability to the measurement (including displacement measurement) related to the height of the BGA solder ball having a spherical shape.

  In the above configuration, the length of the wide spot in the longitudinal direction is preferably equal to or less than the arrangement pitch of the BGA solder balls in the direction orthogonal to the direction of the row.

  According to the present invention, it is possible to improve the working efficiency of measurement related to the height of BGA solder balls arranged in rows on a substrate.

<Embodiment>
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a BGA solder ball height measuring apparatus 1 according to the present embodiment. The solder ball height measuring device 1 has a configuration in which a sensor head unit 11 and a controller unit 12 are connected via a signal cable. In addition, the sensor head part 11 and the controller part 12 may be comprised integrally.

  The sensor head unit 11 includes a laser diode (LD) 15 as a light projecting element, an LD drive circuit 14 for driving the laser diode 15, and a laser beam L 1 emitted from the laser diode 15 on the BGA solder ball 31. A projection lens 16 for irradiating the surface and spot shaping means 17 for forming a wide irradiation spot of the laser beam L1 are provided. The spot shaping means 17 is, for example, an optical slit. The LD driving circuit 14, the laser diode 15, the light projecting lens 16, and the spot shaping means 17 correspond to the “light projecting means” of the present invention. In the present embodiment, the laser beam L1 is irradiated on the surface of the BGA solder ball 31 as a wide irradiation spot (hereinafter, “wide irradiation spot”) LS.

  The sensor head unit 11 further includes a light receiving lens 18, a CCD linear sensor 19 that receives the laser light L 2 that has passed through the light receiving lens 18, and a CCD drive circuit 20 that drives the CCD linear sensor 19. Yes. The light receiving lens 18, the CCD linear sensor 19, and the CCD drive circuit 20 function as position detecting means. The CCD linear sensor 19 includes a plurality of elongated pixels 19b that form a light receiving surface 19a.

  The laser light L 1 emitted from the laser diode 15 passes through the light projecting lens 16 and the spot shaping means 17 and is irradiated on the BGA solder ball 31 on the BGA substrate W. The diffuse reflected light L2 on the surface of the BGA solder ball 31 passes through the light receiving lens 18 and enters the CCD linear sensor 19. In this CCD linear sensor 19, the charge accumulated according to the amount of light received and the relative position of the BGA solder ball 31 is read as a light receiving signal by the CCD drive circuit 20, and the light receiving signal is converted into a time-series voltage signal S1. Is done.

  When the CCD drive circuit 20 gives a predetermined transfer clock to the CCD linear sensor 19, the CCD linear sensor 19 sequentially transfers the charges accumulated in each pixel 19b one pixel at a time. Then, the CCD drive circuit 20 generates a time-series voltage signal S1 corresponding to the accumulated charges of all the pixels, and supplies the voltage signal S1 to the controller unit 12.

  The controller unit 12 includes a CPU 41, a memory 42, operation keys 43, a display unit 44, and the like. The CPU 41 gives a drive signal to the LD drive circuit 14 to cause the laser diode 15 to perform a light projecting operation. Further, the CPU 41 drives the CCD drive circuit 20 at a predetermined cycle by the control signal S2 to execute a light receiving operation for transferring the accumulated charge of each pixel 19b of the CCD linear sensor 19, and the voltage signal from the CCD drive circuit 20 is executed. Receive S1.

  With the above configuration, in the sensor head unit 11, the light receiving position P of the diffuse reflected light L <b> 2 on the light receiving surface 19 a of the CCD linear sensor 19 moves according to the distance from the CCD linear sensor 19 to the apex of the BGA solder ball 31. Then, the CPU 41 can measure the height displacement of the BGA solder ball 31 by detecting the light receiving position P of the diffuse reflected light L2 on the light receiving surface 19a of the CCD linear sensor 19 by analyzing the voltage signal S1. it can.

  More specifically, the CPU 41 receives the voltage signal S1 from the CCD drive circuit 20, detects the pixels with the maximum light reception amount from all the pixels 19b on the light receiving surface 19a of the CCD linear sensor 19, and stores the measurement data in the memory 42. Store time-sequentially in the area. At this time, the CPU 41 functions as “measuring means” of the present invention.

  Next, with reference to FIG. 2 to FIG. 4, a measurement function related to the height h of the BGA solder ball 31 by the BGA solder ball height measuring apparatus 1 will be described. The description of the same configuration as the conventional one shown in FIG. 5 is omitted. FIG. 2 shows a positional relationship between the wide irradiation spot LS irradiated to the BGA solder ball 31 and the CCD linear sensor 19. FIG. 3 is a plan view of the BGA substrate W at the time of measurement according to the present embodiment, and FIG. 4 shows a part of an enlarged cross section along line 4-4 of FIG.

  2 to 4, a direction indicated by an arrow A (hereinafter, “direction A”) indicates a direction in which the wide irradiation spot LS is formed wide, and the width direction of the CCD linear sensor 19 (longitudinal direction of the pixel 19b). ). That is, in the measurement relating to the height h of the BGA solder ball 31, the direction A in which the wide irradiation spot LS is formed wide and the width direction B (longitudinal direction of the pixel 19b) B of the CCD linear sensor 19 are the same direction. It becomes. Here, the wide irradiation spot LS has a land track shape as shown in FIG. Further, as shown in FIG. 3, the direction A is a row direction of the arrangement of the BGA solder balls 31 and is a direction orthogonal to a direction indicated by an arrow M that is a measurement direction (hereinafter referred to as “direction M”). It is. In the measurement, when the BGA substrate is fixed, the sensor head portion 11 is moved in the direction M. On the other hand, when the sensor head portion 11 is fixed, the BGA substrate W is opposite to the direction M. Moved in the direction.

  In the measurement, as shown in FIG. 2, the sensor head unit 11 is configured such that the wide direction A of the irradiation spot LS is the width direction of the CCD linear sensor 19 (longitudinal direction of the pixel 19b) B as described above. Are arranged with respect to the BGA substrate W so as to be in the same direction. Here, the width (length in the longitudinal direction of the pixel 19b) d2 of the CCD linear sensor 19 has at least the width d1 in the wide direction of the irradiation spot LS.

  By arranging and configuring the irradiation spot LS and the CCD linear sensor 19 in this way, the diffuse reflected light L2 on the surface of the BGA solder ball by the laser light L1 having the wide irradiation spot LS is preferably received by the pixel 19b. The That is, the diffuse reflected light L2 from the apex of the BGA solder ball 31 existing in the wide irradiation spot LS is received by the corresponding pixel 19b. At that time, the light receiving position of the related diffuse reflected light L2 in the pixel 19b is the longitudinal direction of the pixel 19b shown in FIG. It moves to B (in the width direction of the CCD linear sensor 19).

  Further, according to the displacement of the height of the BGA solder ball 31, the light receiving position P of the diffuse reflected light L2 from the apex of the BGA solder ball 31 is the longitudinal direction of the CCD linear sensor 19 shown in FIG. ) Shift to C. Therefore, the measurement of the displacement of the height of the BGA solder ball 31 specifically detects the shift of the light receiving position P from the light receiving position Pst corresponding to a predetermined reference height, and uses the shift of the light receiving position P. Done. That is, the CPU 41 changes the height of the BGA solder ball 31 according to the deviation between the light receiving position P of the pixel 19b having the maximum light receiving amount and the reference light receiving position Pst from all the pixels on the light receiving surface 19a of the CCD linear sensor 19. taking measurement. The CPU 41 sequentially measures all the solder balls 31. Further, the CPU 41 compares the displacement with a predetermined reference to determine whether the height h of the BGA solder ball 31 is good. Further, the CPU 41 can determine the height h of the BGA solder ball 31 from the reference height and the measured displacement.

  At that time, even when measuring the displacement of the height of the misaligned BGA solder ball 31A surrounded by the dotted line in FIG. 3, in this embodiment, as shown in FIG. The laser beam L1 is irradiated so as to include the apex Tp of the misaligned BGA solder ball 31A, and the displacement of the height can be measured. Therefore, it is possible to measure the displacement of the heights of a plurality of BGA solder balls arranged in a matrix by a single scan measurement.

  The length d1 of the wide irradiation spot LS in the longitudinal direction A is appropriately determined according to the maximum diameter size of the BGA solder balls 31A, the arrangement pitch P2 of the BGA solder balls 31A, the positional deviation tolerance of the BGA solder balls 31A, and the like. Is set. Here, the length d1 is, for example, a length that exceeds twice the allowable misalignment dimension D of the BGA solder ball 31A from the normal position (L4) of the BGA solder ball 31 shown by a two-dot chain line in FIG. Have That is, the length d1 of the wide irradiation spot LS in the longitudinal direction A has a length of at least 2D (see FIG. 4). Therefore, in this case, as shown in FIG. 4, the laser beam L1 is irradiated so as to reliably include the apex Tp of the misaligned BGA solder ball 31A. The allowable misalignment dimension D usually varies depending on the conditions required for the BGA substrate.

  As described above, according to the configuration of the present embodiment, the measurement of the displacement of the height of the BGA solder ball 31 having a spherical shape is performed with a wide irradiation spot LS in the direction A perpendicular to the column direction M of the BGA solder ball 31. It is done using. Therefore, even when the BGA solder balls 31 are displaced in the direction A perpendicular to the column direction M, the displacement measurement of the height of the displaced BGA solder balls 31A is performed by the BGA substrate W or the sensor head unit. 11 is possible by one movement (scan). As a result, it is not necessary to move the BGA substrate W or the sensor head unit 11 again in order to measure the misaligned BGA solder ball 31A, and the working efficiency is improved.

  Further, the length d1 in the longitudinal direction A of the wide irradiation spot LS has a length that exceeds at least twice the allowable displacement D of the displacement BGA solder ball 31A. Therefore, the displacement measurement of the height of the misalignment BGA solder ball 31A within the allowable misalignment dimension D range is reliably executed. Further, by appropriately setting the length d1 of the wide irradiation spot LS, the BGA solder ball height measuring device 1 according to the present invention can determine whether the positional deviation in the longitudinal direction A of the BGA solder ball 31 is within an allowable range. Can also be used for detection.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above-described embodiment, an example of measuring the height of the BGA solder balls 31 arranged in a matrix on the BGA substrate W has been shown, but the present invention is not limited to this. For example, the BGA solder balls 31 may not be arranged in a matrix, but may be simply arranged in a row. The apparatus according to the present invention is not limited to a BGA solder ball, and can also be applied to measurements related to the height of, for example, a spherical metal, chocolate, or medicine.

  (2) In the above embodiment, an example in which the length d1 in the longitudinal direction A of the wide irradiation spot LS has a length of at least 2D (twice the allowable misalignment dimension D) is shown. It is not limited to. For example, the length d1 in the longitudinal direction A of the wide irradiation spot LS may have a length equal to or less than the arrangement pitch P2 of the BGA solder balls in the direction A orthogonal to the row direction M, or at least 2D or more. Further, it may have a length equal to or less than the arrangement pitch P2. In short, the length d1 in the longitudinal direction A of the wide irradiation spot LS only needs to be larger than the dimension in the column direction M of the wide irradiation spot LS.

  (3) In the above embodiment, the sensor head unit 11 is a so-called diffuse reflection type that receives diffuse reflection light from the BGA solder ball 31, but is not limited thereto. The present invention can also be applied to a so-called specular reflection type sensor head unit that irradiates the BGA solder ball 31 with laser light L1 from the laser diode 15 obliquely from above and receives the specular reflection light.

  (4) In the above embodiment, the configuration in which the CCD linear sensor 19 and the CCD drive circuit 20 are separated is shown. However, the CCD linear sensor 19 and the CCD drive circuit 20 may be integrated. A CMOS linear sensor may be used as the linear image sensor. Further, a position detection element (PSD) may be used instead of the linear image sensor.

1 is an overall schematic diagram of a BGA solder ball height measuring device according to an embodiment of the present invention. Schematic perspective view showing a measurement mode related to the height of a BGA solder ball according to the present invention. The top view which shows the measurement aspect which concerns on the height of the BGA solder ball by this invention Sectional drawing which shows the measurement aspect which concerns on the height of the BGA solder ball by this invention A plan view showing a measurement mode related to the height of a conventional BGA solder ball

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... BGA solder ball height measuring device 11 ... Sensor head part 12 ... Controller part 14 ... LD drive circuit (light projection means)
15 ... Laser diode (light projection means)
16 ... Projection lens (projection means)
17 ... Spot shaping means (light projection means)
DESCRIPTION OF SYMBOLS 18 ... Light receiving lens 19 ... CCD linear sensor 20 ... CCD drive circuit 31 ... BGA solder ball 31A ... Misalignment BGA solder ball 41 ... CPU (measuring means)
42 ... Memory LS ... Wide irradiation spot S1 ... Voltage signal (light reception signal)
W ... BGA substrate

Claims (2)

An apparatus for measuring the height of each of a plurality of BGA solder balls arranged in a row on a substrate, the light projecting means for irradiating the plurality of BGA solder balls with light, and a plurality of pixels The light receiving surface is made of, and the reflected light from the irradiated BGA solder ball is received at a position on the light receiving surface corresponding to the distance from the BGA solder ball, and a light receiving signal corresponding to the light receiving position is generated. An apparatus comprising: a linear image sensor that measures the height of the BGA solder ball based on a light reception signal of the linear image sensor;
The light emitted from the light projecting means is formed so as to have a wide spot in the width direction of the linear image sensor in a direction orthogonal to the direction of the row.
The light projecting means sequentially irradiates each of the plurality of BGA solder balls with light having the wide spot by relative movement with the plurality of BGA solder balls along the column direction ,
BGA solder ball height measurement characterized in that the length of the wide spot in the longitudinal direction is at least twice as large as the misalignment dimension of the BGA solder ball allowed in the direction orthogonal to the direction of the row apparatus.   2. The BGA solder ball height measuring device according to claim 1, wherein a length of the wide spot in a longitudinal direction is equal to or less than a pitch of the BGA solder balls in a direction orthogonal to the direction of the row.

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