U.S. patent application number 13/698684 was filed with the patent office on 2013-04-11 for method of determining solder paste height and device for determining solder paste height.
The applicant listed for this patent is Yousuke Hassaku, Masanori Ikeda, Hiroshi Okamura, Masahiro Taniguchi, Michinori Tomomatsu. Invention is credited to Yousuke Hassaku, Masanori Ikeda, Hiroshi Okamura, Masahiro Taniguchi, Michinori Tomomatsu.
Application Number | 20130089239 13/698684 |
Document ID | / |
Family ID | 46830353 |
Filed Date | 2013-04-11 |
United States Patent
Application |
20130089239 |
Kind Code |
A1 |
Ikeda; Masanori ; et
al. |
April 11, 2013 |
METHOD OF DETERMINING SOLDER PASTE HEIGHT AND DEVICE FOR
DETERMINING SOLDER PASTE HEIGHT
Abstract
A method of determining a solder paste height of solder paste
printed on a circuit board, the method including obtaining a
two-dimensional image of the circuit board which is captured from
above a solder printed surface, and determining the solder paste
height corresponding to a pixel value of each of pixels of the
two-dimensional image, based on height information which defines a
relationship between the pixel value and the solder paste height,
the pixel value being a value representing at least one of
luminance of red in a RGB color model, luminance of green in the
RGB color model, luminance of blue in the RGB color model, hue in a
HSI color model, saturation in the HSI color model, and intensity
in the HSI color model.
Inventors: |
Ikeda; Masanori; (Yamanashi,
JP) ; Tomomatsu; Michinori; (Yamanashi, JP) ;
Taniguchi; Masahiro; (Yamanashi, JP) ; Hassaku;
Yousuke; (Yamanashi, JP) ; Okamura; Hiroshi;
(Kumamoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ikeda; Masanori
Tomomatsu; Michinori
Taniguchi; Masahiro
Hassaku; Yousuke
Okamura; Hiroshi |
Yamanashi
Yamanashi
Yamanashi
Yamanashi
Kumamoto |
|
JP
JP
JP
JP
JP |
|
|
Family ID: |
46830353 |
Appl. No.: |
13/698684 |
Filed: |
February 20, 2012 |
PCT Filed: |
February 20, 2012 |
PCT NO: |
PCT/JP2012/001105 |
371 Date: |
November 19, 2012 |
Current U.S.
Class: |
382/106 |
Current CPC
Class: |
G01B 11/0608 20130101;
G06T 2207/30141 20130101; G06T 2207/10024 20130101; H05K 3/3485
20200801; G06T 7/507 20170101; G01N 21/95684 20130101; G06T
2207/30152 20130101 |
Class at
Publication: |
382/106 |
International
Class: |
G06K 9/00 20060101
G06K009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2011 |
JP |
2011-055865 |
Claims
1. A method of determining a solder paste height of solder paste
printed on a circuit board, the method comprising: obtaining a
two-dimensional image of the circuit board which is captured from
above a solder printed surface; and determining the solder paste
height corresponding to a pixel value of each of pixels of the
two-dimensional image, based on height information which defines a
relationship between the pixel value and the solder paste height,
the pixel value being a value representing at least one of
luminance of red in a RGB color model, luminance of green in the
RGB color model, luminance of blue in the RGB color model, hue in a
HSI color model, saturation in the HSI color model, and intensity
in the HSI color model, wherein the height information shows that a
difference between an intensity value and a hue value in the HSI
color model corresponds to the solder paste height, and in the
determining, the solder paste height is determined by calculating
the difference.
2-5. (canceled)
6. A device for determining a solder paste height printed on a
circuit board, the device comprising: an image obtaining unit
configured to obtain a two-dimensional image of the circuit board
which is captured from above a solder printed surface; and a height
determining unit configured to determine the solder paste height
corresponding to a pixel value of each of pixels of the
two-dimensional image, based on height information which defines a
relationship between the pixel value and the solder paste height,
the pixel value being a value representing at least one of
luminance of red in a RGB color model, luminance of green in the
RGB color model, luminance of blue in the RGB color model, hue in a
HSI color model, saturation in the HSI color model, and intensity
in the HSI color model, wherein the height information shows that a
difference between an intensity value and a hue value in the HSI
color model corresponds to the solder paste height, and the height
determining unit determines the solder paste height by calculating
the difference.
Description
TECHNICAL FIELD
[0001] The present invention relates to methods of determining a
solder paste height of solder paste printed on a circuit board, and
devices for determining a solder paste height of solder paste
printed on a circuit board.
BACKGROUND ART
[0002] A mounted-board manufacturing system, which manufactures
circuit boards on each of which components are mounted
(hereinafter, referred to as "component mounted boards" or "mounted
boards"), includes: a printer that prints solder paste on each
circuit board; mounters that mounts components on the circuit board
with printed solder paste; and a reflow machine that solders the
mounted components.
[0003] Target circuit boards are transported on a line of a
conveyer in the mounted-board manufacturing system and manufactured
as mounted boards in the conveyer system. More specifically,
respective machines perform their processes for each circuit board.
For example, for each circuit board, the printer prints solder
paste on the circuit board, the mounter mounts various-sized
numerous components on the circuit board, and then the reflow
machine solders the components. Each of mounted boards is
manufactured in a series of manufacturing processes performed by
these machines. Such a mounted board manufactured in the
above-described manner is eventually embedded in an end product
such as a home appliance.
[0004] This mounted-board manufacturing system sometimes produces
defective component mounted boards. From among various causes of
poor quality, there is a defect in printing solder paste. For
example, if a defect occurs in printing solder paste on a circuit
board but subsequent processes are performed on the printed board,
in more details, components are mounted and soldered on the circuit
board, this results in various wastes in use of the mounted-board
manufacturing system, consumption of the components, and the
like.
[0005] To reduce the number of defective products and reduce waste
processes in the mounted-board manufacturing system, it is
effective to detect occurrence of a defect in an early stage and
take measures when the defect occurs in the middle of a series of
the manufacturing processes.
[0006] Conventionally, a technique has been proposed by which an
inspection machine arranged for a process subsequent to a printing
process inspects how a printer prints solder paste on each circuit
board (see, Patent literature (PTL) 1 for example). In the
technique as described in PTL 1, position, area, and others of the
printed solder paste are measured using two-dimensional image
captured by a camera with a solid-state image sensing device. In
addition, a height of printed solder paste is also measured using a
laser ranging unit.
[0007] Based on the position, area, and height of the solder paste
measured in such a manner, the inspection machine can inspect how
the printer prints solder paste on each circuit board.
CITATION LIST
Patent Literature
[0008] [PTL 1] Japanese Unexamined Patent Application Publication
No. 2007-134406
SUMMARY OF INVENTION
Technical Problem
[0009] However, the measurement of the height of printed solder
paste using the laser ranging unit, as described in PTL 1, has a
problem that manufacturing cost of the inspection machine
increases. In addition, the machines capable of installing the
laser ranging unit are limited because the laser ranging unit is
relatively heavy. The laser ranging unit also has the problem that
it takes relatively long time to determine the solder paste
height.
[0010] In view of this, the present invention was conceived in
order to solve the above problems, and has an object to provide a
method of determining the solder paste height and a device for
determining the solder paste height, which can determine the height
of printed solder paste in a rather straightforward manner without
using the laser ranging unit.
Solution to Problem
[0011] In order to achieve the object, a method of determining a
solder paste height according to an aspect of the present invention
includes: obtaining a two-dimensional image of the circuit board
which is captured from above a solder printed surface; and
determining the solder paste height corresponding to a pixel value
of each of pixels of the two-dimensional image, based on height
information which defines a relationship between the pixel value
and the solder paste height, the pixel value being a value
representing at least one of luminance of red in a RGB color model,
luminance of green in the RGB color model, luminance of blue in the
RGB color model, hue in a HSI color model, saturation in the HSI
color model, and intensity in the HSI color model
[0012] With this, the solder paste height corresponding to a pixel
value of each of pixels of the two-dimensional image can be
determined, based on height information which defines a
relationship between the pixel value and the solder paste height,
the pixel value being a value representing at least one of
luminance of red in a RGB color model, luminance of green in the
RGB color model, luminance of blue in the RGB color model, hue in a
HSI color model, saturation in the HSI color model, and intensity
in the HSI color model. More specifically, without using a laser
ranging unit, the solder paste height can be determined in a
straightforward manner using a two-dimensional image.
[0013] In addition, it is preferable that the height information
include a proportionality coefficient between an intensity value in
the HSI color model and the solder paste height, and, in the
determining, the solder paste height is determined by multiplying
the intensity value by the proportionality coefficient included in
the height information.
[0014] With this, the solder paste height can be determined easily
by using a proportional relationship between the solder paste
height and the intensity value in the HSI color model.
[0015] In addition, it is preferable that the height information
include a proportionality coefficient between a luminance value of
blue in the RGB color model and the solder paste height, and, in
the determining, the solder paste height is determined by
multiplying the luminance value of blue by the proportionality
coefficient included in the height information.
[0016] With this, the solder paste height can be determined easily
by using a proportional relationship between the solder paste
height and the luminance value of blue. A two-dimensional image
generated by a general imaging device is an image represented using
the RGB color model. Therefore, this method does not necessitate
converting the two-dimensional image represented using the RGB
color model, which is obtained from the imaging device, to a
two-dimensional image represented using the HSI color model, thus
reducing a processing load.
[0017] In addition, it is preferable that the height information
show that a difference between an intensity value and a hue value
in the HSI color model corresponds to the solder paste height, and,
in the determining, the solder paste height is determined by
calculating the difference.
[0018] With this, the solder paste height can be determined by
using the correspondence of the solder paste height to the
difference between the intensity value and the hue value. As a
result, regardless of the type of circuit board, the solder paste
height can be determined generally.
[0019] In addition, it is preferable that the method further
include displaying the determined solder paste height.
[0020] With this, the heights of solder paste can be displayed for
an inspector to visually inspect how the solder paste is printed on
each circuit board.
[0021] In addition, a device for determining the solder paste
height according to an aspect of the present invention includes: an
image obtaining unit which obtains a two-dimensional image of the
circuit board which is captured from above a solder printed
surface; and a height determining unit which determines the solder
paste height corresponding to a pixel value of each of pixels of
the two-dimensional image, based on height information which
defines a relationship between the pixel value and the solder paste
height, the pixel value being a value representing at least one of
luminance of red in a RGB color model, luminance of green in the
RGB color model, luminance of blue in the RGB color model, hue in a
HSI color model, saturation in the HSI color model, and intensity
in the HSI color model.
[0022] With this structure, such a device has an advantageous
effect similar to the above method.
Advantageous Effects of Invention
[0023] According to this present invention, heights of solder paste
printed on a circuit board can be determined in a rather
straightforward manner without using a laser ranging unit.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 illustrates an outline view of an inspection machine
according to an embodiment of the present invention.
[0025] FIG. 2A illustrates an elevation view of the inspection
machine according to the embodiment of the present invention.
[0026] FIG. 2B illustrates a bottom view of the inspection machine
according to the embodiment of the present invention.
[0027] FIG. 3 illustrates a cross-sectional view to describe a
lighting device included in the inspection machine according to the
embodiment of the present invention.
[0028] FIG. 4 illustrates a block diagram showing a functional
structure of the inspection machine according to the embodiment of
the present invention.
[0029] FIG. 5 illustrates a flowchart showing a method of
determining a solder paste height according to the embodiment of
the present invention.
[0030] FIG. 6 illustrates an exemplary display of the solder paste
height according to the embodiment of the present invention.
DESCRIPTION OF EMBODIMENT
[0031] In some experiments, inventors of this application found
that a pixel value in a two-dimensional image generated by
capturing a circuit board with printed solder paste (i.e. a value
represented using the RGB color model or the HSI color model)
depends on a solder paste height. The following paragraphs will
describe an embodiment according to the present invention in which
dependency between the pixel value of the two-dimensional image and
the solder paste height is utilized to determine the solder paste
height based on the two-dimensional image.
[0032] Note that the embodiment described below is a preferable,
specific example of the present invention. The numerical values,
shapes, constituent elements, the arrangement and connection of the
constituent elements, steps, the processing order of the steps etc.
shown in the following embodiment is a mere example, and thus do
not limit the present invention. Thus, among the constituent
elements in the following embodiment, constituent elements not
recited in any of the independent claims indicating the most
generic concept of the present invention are described as
preferable constituent elements.
Embodiment
[0033] A device for determining a solder paste height 130 according
to an embodiment of the present invention determines a solder paste
height corresponding to a pixel value of each of pixels of a
two-dimensional image, based on height information which defines a
relationship between the pixel value and the solder paste height.
Hereinafter, the embodiment will be described with reference to
drawings.
[0034] FIG. 1 illustrates an outline view of an inspection machine
according to the embodiment of the present invention. FIG. 2A
illustrates an elevation view (partial cross-sectional view) of the
inspection machine according to the embodiment of the present
invention. FIG. 2B illustrates a bottom view of the inspection
machine as shown in FIG. 2A, where the inspection machine is
depicted from the bottom in a direction of Z-axis. FIG. 3
illustrates a cross-sectional view to describe a lighting device
according to the embodiment of the present invention. FIG. 4
illustrates a block diagram showing a functional structure of the
inspection machine according to the embodiment of the present
invention. Note that, in the above drawings, a solder printed
surface of the circuit board is parallel to X-Y plane, and the
Z-axis corresponds to the solder paste height.
[0035] As shown in FIG. 1 to FIG. 4, the inspection machine 100
includes an imaging device 110, a lighting device 120, and the
device for determining the solder paste height 130.
[0036] The imaging device 110 captures a circuit board 200 with
printed solder paste to generate the two-dimensional image. In the
embodiment, the imaging device 110 generates the two-dimensional
image represented using the RGB (Red, Green, Blue) color model.
More specifically, the imaging device 110 includes an imaging
sensor 111 and an optical system 112 as shown in FIG. 1 and FIG.
2.
[0037] The imaging sensor 111 is a solid-state image sensing device
such as a charge coupled device (CCD) imaging sensor or a
complementary metal oxide semiconductor (CMOS) imaging sensor. In
the embodiment, for the imaging sensor 111, the CCD imaging sensor
is used which converts light that has passed through the optical
system 112 to respective electric signals of the RGB components.
The imaging sensor 111 generates the two-dimensional image
represented using the RGB color model, which comprises more than 1
million pixels for example.
[0038] The optical system 112 includes lens which collects light
reflected from the circuit board 200 in the imaging area of the
imaging sensor 111. Note that an optical axis of the optical system
112 is depicted as dashed line.
[0039] The lighting device 120 emits light to the circuit board
200. The lighting device 120 includes a coaxial lighting unit 121
and a side lighting unit 122.
[0040] The coaxial lighting unit 121 is a light source which is
located above the circuit board 200 and emits light downward to it.
More specifically, the coaxial lighting unit 121 emits light to a
point on top surface of the circuit board 200 where the optical
axis of the optical system 112 and the circuit board 200 intersect,
in a direction of about 90 degrees from the surface of the circuit
board 200 (in a direction of Z-axis). In the embodiment, the
coaxial lighting unit 121 has a light-emitting diode (LED) that
emits white light and a LED that emits red light. The LED that
emits white light and the LED that emits red light are arranged
alternately.
[0041] The side lighting unit 122 arranged in a circular pattern is
a light source which is located lateral to the circuit board 200
and emits light obliquely downward to it. In the embodiment, the
side lighting unit 122 includes a first side lighting unit 122a and
a second side lighting unit 122b.
[0042] The first side lighting unit 122a is arranged above the
second side lighting unit 122b and emits light obliquely downward
to the circuit board 200. In the embodiment, a LED that emits white
light is used as the first side lighting unit 122a. In this case,
as shown in FIG. 3, the first side lighting unit 122a emits light
to the point where the optical axis of the optical system 112 and
the circuit board 200 intersect, in a direction of about 50 degrees
from the surface of the circuit board 200 for example.
[0043] The second side lighting unit 122b is arranged below the
first side lighting unit 122a and emits light obliquely downward to
the circuit board 200. In the embodiment, a LED that emits white
light is used as the second side lighting unit 122b. In this case,
as shown in FIG. 3, the second side lighting unit 122b emits light
to the point where the optical axis of the optical system 112 and
the circuit board 200 intersect, in a direction of about 35 degrees
from the surface of the circuit board 200 for example.
[0044] Thus, in the side lighting unit 122, each of the first side
lighting unit 122a and the second side lighting unit 122b emits
light to the circuit board 200 at a different angle to avoid making
a shadow on the solder printed surface of the circuit board
200.
[0045] The following paragraphs will describe the device for
determining the solder paste height 130 with reference to FIG.
4.
[0046] The device for determining the solder paste height 130 can
be implemented as a processor, a memory, and the like, and
determines the solder paste height of solder paste printed on the
circuit board 200 based on the two-dimensional image captured by
the imaging device 110. As shown in FIG. 4, the device for
determining the solder paste height 130 includes an image obtaining
unit 131 and a height determining unit 132.
[0047] The image obtaining unit 131 obtains the two-dimensional
image of the circuit board 200. More specifically, the image
obtaining unit 131 obtains the two-dimensional image of the circuit
board 200 which is captured from above the solder printed
surface.
[0048] In the embodiment, the image obtaining unit 131 obtains the
two-dimensional image represented using the RGB color model from
the imaging device 110. Subsequently, the image obtaining unit 131
converts the two-dimensional image represented using the RGB color
model (hereinafter referred to as a "RGB image") to a
two-dimensional image represented using the Hue, Saturation, and
Intensity (HSI) color model (hereinafter referred to as a "HSI
image").
[0049] The height determining unit 132 determines the solder paste
height corresponding to the pixel value of each of pixels of the
two-dimensional image, based on the height information which
defines the relationship between the solder paste height and the
pixel value that is a value representing at least one of luminance
of red in the RGB color model, luminance of green in the RGB color
model, luminance of blue in the RGB color model, hue in the HSI
color model, saturation in the HSI color model, and intensity in
the HSI color model. In the embodiment, the height information
shows that the solder paste height is proportional to the pixel
value, and contains a proportionality coefficient between the
solder paste height and the pixel value (for example "0.5"). More
specifically, the height determining unit 132 determines the solder
paste height by multiplying an intensity value by the
proportionality coefficient between the intensity value and the
solder paste height.
[0050] Note that the height information need not contain the
proportionality coefficient. For example, the height information
may be created in table form which stores the solder paste height
in association with the pixel value.
[0051] In addition, it is preferable that the height information be
stored for each type of circuit board 200 and each type of land
processing which is performed on conductor pattern surface that is
a captured surface of the circuit board 200. For example, it is
preferable to separately store height information sets such as when
copper is used in land processing of a glass epoxy board, when gold
is used in land processing of a glass epoxy board, and when copper
is used in land processing of a polyimide board. With this, the
device for determining the solder paste height 130 can
appropriately determine the solder paste height according to the
type of circuit board or land processing. Note that the land
processing includes a processing where no surface treatment is
performed on land material.
[0052] A display unit 133 such as a liquid crystal display panel
displays the determined heights. More specifically, the display
unit 133 displays, as a three-dimensional chart, the height for
each of the pixels included in the two-dimensional image.
[0053] A glass epoxy board, a polyimide board, flexible board,
ceramic board, or the like is used as the circuit board 200.
[0054] The following paragraphs will describe various operations in
the above-mentioned inspection machine 100.
[0055] FIG. 5 illustrates a flowchart showing a method of
determining a solder paste height according to the embodiment of
the present invention. Note that, in the following method of
determining the solder paste height, height information appropriate
to the circuit board 200 is created and stored in advance.
[0056] The image obtaining unit 131 obtains the two-dimensional
image of the circuit board 200 (S201). In the embodiment, the image
obtaining unit 131 obtains the two-dimensional image represented
using the RGB color model (the RGB image) from the imaging device
110. Then, the height determining unit 132 converts the RGB image
into a HSI image (S202).
[0057] Subsequently, for each pixel of the captured two-dimensional
image (the RGB image, the HSI image, and so on), the height
determining unit 132 determines a solder paste height corresponding
to a pixel value of the pixel based on height information which
defines a relationship between the pixel value (the RGB color
model, the HSI color model) and the solder paste height (S203). In
the embodiment, the height information shows that the solder paste
height is proportional to an intensity value in the HSI image. For
example, when the height information contains a proportionality
coefficient 0.5 and intensity value of a pixel included in the HSI
image is 225, the height determining unit 132 determines that the
solder paste height in the pixel is 112.5 .mu.m (solder paste
height=intensity value.times.proportionality coefficient).
[0058] The display unit 133 displays the solder paste height
determined in such a manner (S204). For example, as shown in FIG.
6, the display unit 133 displays the solder paste height in each
pixel position as a three-dimensional chart. With this, an
inspector can easily check how the solder paste is printed on each
circuit board 200 by looking at the three-dimensional chart
displayed on the display unit 133.
[0059] Note that the height information can be created by measuring
the solder paste height and the intensity value in the HSI image
generated by capturing the board with solder paste having a known
height. An exemplary process of creating such height information
will be described below.
[0060] First, the circuit board 200 with printed solder paste
having a predetermined height is captured by the imaging device
110. Subsequently, the captured RGB image is converted into the HSI
image. In the converted HSI image, an intensity value of a pixel
corresponding to a position where the solder paste is printed is
detected. A proportion of the solder paste height of solder paste
printed on the circuit board 200 (the predetermined height) to the
intensity value detected above is calculated as the proportionality
coefficient.
[0061] As described above, the proportionality coefficient between
the intensity value and the solder paste height is calculated. Note
that it is preferable to adjust the light of the lighting device
120 so as to saturate the intensity value corresponding to an upper
limit for the solder paste height to be determined (for example,
255 for 256 grayscales). With this, the solder paste height can be
determined more precisely.
[0062] It is also preferable to capture a reference board (for
example, a matte black circuit board) in the light of the lighting
device 120 adjusted above in order to calculate the hue, saturation
and intensity values in the HSI image as reference values (for
example, H(50/255), S(50/255) and I(100/255)). With this, when the
lighting device 120 is adjusted so as to match a value of the HSI
image obtained as a result of capturing the reference board to the
reference value (for example, the first side lighting unit
(20/255), the second side lighting unit (200/255)), the process
does not necessitate the recalculation of the proportionality
coefficient using the circuit board with printed solder paste.
[0063] As described above, the inspection machine 100 according to
the embodiment can determine the solder paste height corresponding
to the pixel value of each pixel of the two-dimensional image,
based on the height information which defines the relationship
between the pixel value and the solder paste height. In other
words, without using the laser ranging unit, the solder paste
height can be determined in the straightforward manner using the
two-dimensional image. More specifically, the solder paste height
can be determined easily by using the proportional relationship
between the solder paste height and the intensity value in the HSI
image.
Variation 1
[0064] The following paragraphs will describe a variation 1 of the
present invention.
[0065] In the above-mentioned embodiment, intensity value in an HSI
image is used to determine a solder paste height, whereas, in the
variation 1, a luminance value of blue in a RGB image is used to
determine the solder paste height.
[0066] More specifically, the height determining unit 132 according
to the variation 1 determines the solder paste height by
multiplying the luminance value of blue by the proportionality
coefficient between the luminance value of blue and the solder
paste height, which is contained in height information.
[0067] Among the luminance values of red, green, and blue in the
RGB image, the luminance value of blue is the closest to the
intensity value in the HSI image. Thus, the height determining unit
132 can also determine the solder paste height using the luminance
value of blue in the RGB image as described in the variation 1.
[0068] Therefore, since the solder paste height can be determined
using the luminance value of blue, the device for determining the
solder paste height 130 does not necessitate converting the RGB
image to the HSI image (S202), thus reducing a processing load.
Variation 2
[0069] The following paragraphs will describe a variation 2 of the
present invention.
[0070] In the above-mentioned embodiment, among hue, saturation,
and intensity values in an HSI image, only the intensity value is
used to determine a solder paste height, whereas, in the variation
2, a difference between the intensity value and the hue value is
used to determine the solder paste height.
[0071] In other words, the height determining unit 132 according to
the variation 2 determines the solder paste height by subtracting
the hue value from the intensity value in the HSI image. More
specifically, assuming that the intensity value and the hue value
is 225 and 112, respectively, the height determining unit 132
determines that the solder paste height is 113 .mu.m (solder paste
height=intensity value-hue value).
[0072] The difference between the intensity value and the hue value
corresponds to the solder paste height because the hue value
corresponds to a height of a virtual resist surface (a surface of
the circuit board 200 (a reference surface of height)). This
virtual resist surface corresponds the green solder-resist surface
for protecting a surface (green resist surface) when the glass
epoxy board (so-called "printed circuit board") is used as a
circuit board 200 for example. Therefore, when a color of the
reference surface of height which is the surface of the circuit
board 200 differs from a color of a measured surface, a use of the
difference between the intensity value and the hue value allows the
height determining unit to determine the solder paste height
regardless of the type of circuit board, thus expanding the
versatility.
[0073] Note that, when there is little difference in color between
the reference surface of height and a surface to be measured,
another reference surface of height having a color vastly different
from the color of the surface to be measured may be provided inside
or outside the circuit board to measure the solder paste
height.
[0074] The height determining unit 132 determines the solder paste
height by subtracting the hue value from the intensity value in the
HSI image, but the solder paste height may be also further
determined using a correction value such as a proportionality
coefficient in order to determine the solder paste height more
precisely.
[0075] Thus, the device for determining the solder paste height 130
according to an aspect of the present invention has been described
based on the embodiment, but the present invention is not limited
to this embodiment. Various modifications to the present embodiment
that can be conceived by those skilled in the art, and forms
configured by combining constituent elements in different
embodiments without departing from the teachings of the present
invention are included in the scope of the present invention.
[0076] For example, in the above embodiment, the device for
determining the solder paste height 130 includes the display unit
133, but it need not be included. More specifically, the method of
determining the solder paste height as shown in FIG. 5 need not
include Step S204. In this case, the device for determining the
solder paste height 130 can provide information indicating the
determined height (value, graph of height, and the like) to a
display device for example.
[0077] The device for determining the solder paste height 130 may
also further determine an area in which solder paste is printed on
the circuit board 200, based on the two-dimensional image. Then,
the device for determining the solder paste height 130 may
determine an amount of solder paste based on the determined area
and the determined height. With this, an inspector can inspect more
precisely how the solder paste is printed on each circuit
board.
[0078] Furthermore, the imaging device 110 may capture a solder
printed surface of the circuit board 200 by scanning relatively
because the imaging device need not capture the whole solder
printed surface at one time. More specifically, the imaging device
110 may include a line imaging sensor as the imaging sensor 111
instead of an area imaging sensor which need not be included as the
imaging sensor 111.
[0079] In addition, the inspection machine 100 may determine
whether or not the determined solder paste height is within the
predetermined range of heights in order to inspect how the solder
paste is printed on the circuit board 200. The inspection machine
100 may also provide a warning alarm or turn on an alert lamp when
the inspection is not passed for example. Thus, this reduces an
inspector's burden.
[0080] In addition, the device for determining the solder paste
height 130 may be provided outside the inspection machine 100
because it need not include the device for determining the solder
paste height. Furthermore, the inspection machine 100 may be
included in a mounter or a printer.
[0081] In addition, a part or all of the constituent elements
included in the device for determining the solder paste height 130
according to the embodiment may be configured of one system large
scale integration (LSI). For example, the device for determining
the solder paste height 130 may be configured of a system LSI
having the image obtaining unit 131 and the height determining unit
132.
[0082] The system LSI is a super multi-function LSI that is
manufactured by integrating plural components in one chip, and is
specifically a computer system which is configured by including a
microprocessor, a ROM, a RAM, and so on. A computer program is
stored in the RAM. The system LSI accomplishes its functions
through the operation of the microprocessor in accordance with the
computer program.
[0083] The name used here is a system LSI, however, it may also be
referred to as an IC, an LSI, a super LSI, or an ultra LSI in
accordance with the degree of integration. Furthermore, the
integration may be achieved, not only as LSI, but also as a
dedicated circuit or a general purpose processor. Field
Programmable Gate Array (FPGA) that can be programmed after
manufacturing LSI or reconfigurable processor that can re-configure
the connection and setting of the circuit sell inside the LSI may
be used.
[0084] Furthermore, when integration circuit technology replacing
LSI emerges with the advancement of semiconductor technology or
other derivative technology, the technology may be used naturally
for integrating functional block. Possibility includes application
of biotechnology.
[0085] It should be noted that the present invention can be
implemented, not only as a device for determining a solder paste
height which includes such distinctive processing units, but also
as a method of determining a solder paste height which has, as
steps, the distinctive processing units included in the device for
determining the solder paste height. The present invention can also
be implemented as a program which causes a computer to execute each
of the distinctive steps included in the method of determining the
solder paste height. Needless to say, such a program can be
distributed via a non-transitory computer-readable recording medium
such as a Compact Disc Read Only Memory (CD-ROM) or via a
communication network such as the Internet.
INDUSTRIAL APPLICABILITY
[0086] The present invention is applicable to a device for
determining a solder past height of solder past printed on the
circuit board and an inspecting machine for inspecting how the
solder paste is printed on each circuit board prior to mounting
components on each circuit board.
REFERENCE SIGNS LIST
[0087] 100 Inspection machine [0088] 110 Imaging device [0089] 111
Imaging sensor [0090] 112 Optical system [0091] 120 Lighting device
[0092] 121 Coaxial lighting unit [0093] 122 Side lighting unit
[0094] 122a First side lighting unit [0095] 122b Second side
lighting unit [0096] 130 Device for determining a solder paste
height [0097] 131 Image obtaining unit [0098] 132 Height
determining unit [0099] 133 Display unit [0100] 200 Circuit
board
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