JP2015138890A - Solder discrimination method and printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine whether solder is lead-free solder or lead solder.SOLUTION: A solder discrimination method comprises steps of: forming a dummy land for discrimination (a land-forming step P1); applying paste-like solder to the land for discrimination (an application step P2); heating and melting the paste-like solder (a reflow step P4); and inspecting appearance of the solder which is solidified after being melted (an appearance inspection step P5). In the application step P2, the paste-like solder is applied to the land for discrimination so that a predetermined clearance is formed between first and second portions of the solder. In the appearance inspection step P5, it is inspected whether or not there is the clearance in the solder after reflow. When an inspection result shows that there is the clearance, such solder is determined as lead-free solder. When the inspection result shows that there is no clearance, such solder is determined as lead solder.

Description

  The present invention relates to a solder discrimination method for discriminating whether a solder used for a printed wiring board is a lead-free solder or a lead solder, and a printed circuit board including an electronic component mounted with the lead-free solder.

  In recent years, there has been an increasing demand for using lead-free solder that does not contain lead in place of solder containing lead (lead solder). In some cases, a product that uses lead solder and a product that uses lead-free solder are switched by a single production facility. In this case, there is a fear that lead-free solder is erroneously used for a product scheduled to use lead solder, or that lead solder is erroneously used for a product scheduled to use lead-free solder.

  With respect to this problem, Patent Document 1 discloses a method for discriminating between lead-free solder and lead solder as follows. That is, apart from the original land on which the electronic component is mounted, a dummy discrimination land is formed on the printed wiring board, and paste solder is applied to the central portion of the discrimination land. Then, when the solder melts and spreads on the discrimination land in the subsequent reflow process, the spread area becomes larger as the solder has higher wettability. That is, in the case of lead solder with high wettability, the expansion area becomes larger than in the case of lead-free solder with low wettability. Therefore, in Patent Document 1, the spread area of the solder in the determination land is measured, and when the measured value is smaller than the threshold value, it is determined as lead-free solder, and when the measured value is larger than the threshold value, it is determined as lead solder.

JP 2010-67923 A

  However, it is difficult to accurately measure the above-described spread area, and the measurement error is large. Therefore, in the discrimination method of Patent Document 1, there is a possibility that the discrimination between lead-free solder and lead solder is erroneous.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a solder discrimination method that can discriminate between lead-free solder and lead solder with high accuracy. Another object of the present invention is to provide a printed circuit board using lead-free solder, which can confirm that lead-free solder is normally used.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the invention. .

  One of the disclosed inventions is a solder discrimination method. This solder discrimination method is a solder discrimination method for discriminating whether the solder applied to the printed wiring boards (12, 120) is lead-free solder (Sf) or lead solder (Sp). Have.

  That is, when manufacturing a printed wiring board (12) by forming a land on an insulating substrate, a dummy discrimination is performed separately from the lands (R1, R2, R3) on which the electronic components (13, 14, 15) are mounted. A land forming step (P1) for forming a land (R), a coating step (P2) for applying paste-like solder (S, Sf, Sp) to the land and the discrimination land, and heating the paste-like solder. And a reflow step (P4) for melting and an appearance inspection step (P5) for inspecting the appearance of the solidified solder after melting. In the application step, when applying the paste-like solder to the discrimination land, a predetermined gap (SL, SLa) is provided between the first part (Sp1, Sf1) and the second part (Sp2, Sf2) of the solder. In the appearance inspection process, the appearance inspection is performed to determine whether or not there is a gap in the reflowed solder. If the inspection result indicates that there is a gap, it is determined that the solder is lead-free solder. However, if the inspection result indicates that there is no gap, it is determined that the solder is lead solder.

  The present invention utilizes the fact that lead solder has higher wettability than lead-free solder and has a wide range of melting and spreading on the land in the reflow process. That is, in the case where lead solder is used in the coating process, if the reflow process is performed, the range is expanded over a wider range than in the case where lead-free solder is used. Therefore, when using lead solder, the melted and expanded solder fills the gap, and when using lead-free solder, the size of the gap is such that the gap is not filled even when melted and expanded. Can be set.

  In view of this point, in the present invention, when applying the paste-like solder to the discrimination land, a predetermined gap is formed between the first portion and the second portion of the solder. Then, an appearance inspection is performed to determine whether or not there is a gap in the solder after reflow. If there is a gap, it is determined that the solder is lead-free solder, and if there is no gap, the solder is determined to be lead solder. Therefore, it is not necessary to measure the spread area of solder as in the past, and it is possible to discriminate solder by visual inspection for the presence or absence of gaps, so it is highly accurate whether it is lead-free solder or lead solder Can be discriminated.

  One of the disclosed inventions is a printed circuit board. This printed circuit board is based on the premise that it includes a printed wiring board (12) and electronic components (13, 14, 15) mounted on lands (R1, R2, R3) of the printed wiring board. Has characteristics.

  That is, the printed wiring board has a dummy discrimination land (R) on which an electronic component is not mounted separately from the land, and the land and the discrimination land have lead-free solder (S, Sf) by a reflow method. The lead-free solder connected to the discrimination land has a shape having a predetermined gap (SL, SLa) between the first part (Sf1) and the second part (Sf2) of the lead-free solder. It is characterized by being.

  According to the present invention, it can be confirmed that lead-free solder is normally used by confirming that a gap exists after reflow. The reason will be described below. First, lead solder has higher wettability than lead-free solder, and has a wider range of expansion on the land during reflow. Therefore, the size of the gap can be set so that the gap is filled with molten solder when lead solder is used, and the gap is not filled when lead-free solder is used. With this setting, there is a gap even after reflow when lead-free solder is used normally, and there is a gap after reflow when lead solder is used by mistake. Disappear. Therefore, it can be confirmed that lead-free solder is used by confirming the existence of the gap.

The rear view of the meter apparatus provided with the printed circuit board which concerns on 1st Embodiment of this invention. The figure which shows the manufacturing line of the printed circuit board in FIG. The figure which shows the procedure of the manufacturing process by the manufacturing line of FIG. The figure which shows the state of the solder before the reflow applied to the land for discrimination | determination in 1st Embodiment. FIG. 4 is a diagram showing a state of solder after reflow applied to a discrimination land in the first embodiment, and is a diagram when lead solder is used. FIG. 4 is a diagram showing a state of solder after reflow applied to a discrimination land in the first embodiment, and is a diagram when lead-free solder is used. Sectional drawing which follows the VII-VII line of FIG. Sectional drawing which follows the VIII-VIII line of FIG. Sectional drawing which shows the external appearance inspection machine in FIG. The schematic diagram which shows the reflection angle of the red light by the red light source of the external appearance inspection machine of FIG. The schematic diagram which shows the reflection angle of the green light by the green light source of the external appearance inspection machine of FIG. The schematic diagram which shows the reflection angle of the blue light by the blue light source of the external appearance inspection machine of FIG. The perspective view which shows the fillet part of the solder used as the object of an external appearance test | inspection. The figure which shows the image of a solder shape in case joining of components and solder is normal. The figure which shows the brightness distribution of each color. The figure which shows the image of the solder shape in case the components and solder are not joined. The perspective view which shows the shape after reflow of the lead solder provided in the land for discrimination | determination in 1st Embodiment. The perspective view which shows the shape after reflow of the lead-free solder provided in the land for discrimination | determination in 1st Embodiment. The figure which shows the brightness distribution of each color in the lead solder shown in FIG. The figure which shows the brightness distribution of each color in the lead-free solder shown in FIG. The figure which shows the result of binarizing the brightness distribution shown in FIG. The flowchart which shows the procedure of the discrimination | determination process which the microcomputer in FIG. 9 implements. In 2nd Embodiment of this invention, it is a figure which shows the state of the solder after the reflow applied to the discrimination land, Comprising: The figure at the time of using lead solder. In 2nd Embodiment, it is a figure which shows the state of the solder after the reflow applied to the discrimination land, Comprising: The figure at the time of using lead solder. The figure which shows the state of the solder before the reflow applied to the discrimination land in 3rd Embodiment of this invention. In 3rd Embodiment, it is a figure which shows the state of the solder after the reflow applied to the discrimination land, Comprising: The figure at the time of using lead solder. In 3rd Embodiment, it is a figure which shows the state of the solder after the reflow applied to the discrimination land, Comprising: The figure at the time of using lead-free solder. The top view of the printed circuit board in which the land for discrimination | determination was formed in the solder discrimination | determination method concerning 4th Embodiment of this invention.

  Embodiments in which a solder discrimination method and a printed circuit board according to the present invention are applied to a meter device mounted on a vehicle will be described below with reference to the drawings. Hereinafter, in each embodiment, the same reference numerals are given to portions corresponding to the matters described in the preceding embodiment, and redundant description may be omitted. In each embodiment, when only a part of the configuration is described, the other configurations described above can be applied to other portions of the configuration.

(First embodiment)
A meter device 10 shown in FIG. 1 is configured by housing a printed wiring board 12 in a case 11. Electronic components such as a microcomputer (microcomputer 13), a motor 14, and a connector 15 are mounted on the printed wiring board 12. The microcomputer 13 controls the operation of the motor 14 based on vehicle information acquired from the outside through the connector 15. A pointer (not shown) is connected to the motor 14, and the pointer rotates and indicates a scale indicating a physical quantity such as a vehicle speed according to vehicle information.

  These electronic components are mounted on the lands R1, R2, and R3 of the printed wiring board 12. For example, the terminal 13a of the microcomputer 13 is surface-mounted on the land R1. Furthermore, the printed wiring board 12 has dummy discrimination lands R in addition to the original lands R1, R2, and R3 on which electronic components are mounted.

  Lead-free solders S and Sf are connected to the lands R1, R2, and R3 and the discrimination land R by a reflow method. The lead-free solder Sf connected to the discrimination land R has a shape having a predetermined gap (slit SL) between the first portion Sf1 and the second portion Sf2 of the lead-free solder. Since the slit SL has a slit shape that crosses the discrimination land R, the first portion Sf1 and the second portion Sf2 are separated from each other on the discrimination land R without contacting each other.

  Reference sign B6 in FIG. 2 indicates a printed circuit board using lead-free solder, and an electronic component is mounted on the printed wiring board 12 shown in FIG. This printed circuit board B6 is manufactured through a state indicated by reference numerals B1, B2, B3, B4, and B5 by a production line LB for lead-free solder. On the other hand, symbol A6 indicates a printed circuit board using lead solder. The printed circuit board A6 is manufactured by the lead solder manufacturing line LA through the states indicated by reference signs A1, A2, A3, A4, and A5.

  The printed circuit boards A6 and B6 manufactured in the respective manufacturing lines LA and LB have the same configuration except that the solder material is different. In these production lines LA and LB, a common production apparatus is installed, and the production procedure is the same. Therefore, the lead solder production line LA can be switched to lead-free solder, or the lead-free solder production line LB can be switched to lead solder.

  Hereinafter, the equipment of the production line LB for lead-free solder will be described. First, the printed wiring board B1 is carried into the production line LB for lead-free solder. This printed wiring board B1 has printed wiring (not shown), lands R1, R2, R3 and a discrimination land R shown in FIG. 1 formed on an insulating substrate. The loaded printed wiring board B1 is sent to the printing machine 20.

  The printer 20 prints paste solder on the lands R1, R2, R3 and the discrimination land R of the printed wiring board B1. As this solder, lead-free solder is used. The worker HB puts the cartridge C containing lead-free solder into the printing machine 20. In this loading operation, if the cartridge CPb containing the lead solder is erroneously inserted, the lead solder is erroneously used for the printed circuit board A6 where the lead-free solder is to be used. The printed wiring board B2 on which the paste-like solder is printed is sent to the component placement machine 30.

  The component placement machine 30 places electronic components such as the microcomputer 13, the motor 14, and the connector 15 on predetermined positions of the printed wiring board B2. For example, the microcomputer 13 is placed on the printed wiring board B2 so that the terminal 13a of the microcomputer 13 is positioned on the solder printed on the land R1. The printed wiring board B3 on which various electronic components are placed is sent to the reflow machine 40.

  The reflow machine 40 heats and melts the paste-like solder. For example, the whole printed wiring board B3 may be heated using a heating unit that generates infrared rays, hot air, or the like, or a solder portion may be locally heated using a heating unit such as a laser. The heated and melted solder is then gradually cooled and solidified. As a result, the electronic component is electrically connected to the lands R1, R2, and R3 via the solder, and is mounted on the printed wiring board B3 by soldering. The printed wiring board B4 on which the electronic components are mounted, that is, the printed circuit board, is sent to the soldering appearance inspection machine 50.

  The appearance inspection machine 50 determines the quality by inspecting the soldering state. Specifically, the appearance of solder solidified after melting is inspected to determine whether the amount of solder is excessive or insufficient and whether there is a short circuit due to a solder bridge. Further, the appearance inspection machine 50 determines whether the solder is lead-free solder or lead solder by inspecting the appearance of the solder in the determination land R. That is, the appearance inspection machine 50 installed in the lead-free solder production line LB determines that the solder type is abnormal when it is determined that the solder is lead solder. On the other hand, when the appearance inspection machine 50 installed in the lead solder production line LA is determined to be lead-free solder, it determines that the solder type is abnormal. The solder type discrimination method by the appearance inspection machine 50 will be described later in detail with reference to FIGS.

  The printed circuit board B <b> 5 that has passed the inspection by the appearance inspection machine 50 is sent to the electrical inspection device 60. The electric inspection device 60 energizes a predetermined portion of the printed circuit board B5 to inspect whether or not the circuit operates normally. The printed circuit board B6 that has passed the inspection by the electrical inspection device 60 is carried out of the production line LB.

  Information on the inspection result by the appearance inspection machine 50 is transmitted to the integrated management apparatus 70. The integrated management device 70 records the transmitted inspection result, and notifies the worker H of the fact that the inspection result of the solder connection failure or the solder type abnormality is transmitted. Thereby, the worker H can operate the production lines LA and LB in accordance with the notification contents. For example, when it is notified that the solder type is abnormal, it is possible to minimize the number of manufactured printed circuit boards (defective products) with an abnormal solder type by operating the corresponding production line immediately.

  FIG. 3 is a flowchart showing a manufacturing procedure of the printed circuit boards A6 and B6 described above. First, in the first procedure P1 (land formation step), the lands R1, R2, and R3 and the discrimination land R are formed on an insulating substrate to manufacture printed wiring boards A1 and B1. The first procedure P1 is performed in the pre-procedure of the production lines LA and LB.

  In the subsequent second procedure P2 (application process), paste-like solder is printed on the lands R1, R2, R3 and the discrimination land R using the printing machine 20. At the time of printing, masking is applied to the position where the above-mentioned slit SL is provided in the discrimination land R, and as a result, the solder Sp and Sf (see FIG. 4) printed on the discrimination land R are slit. SL is formed.

  In the following third procedure P3, electronic components are placed at predetermined positions on the printed wiring boards A2 and B2 using the component placement machine 30. In the subsequent fourth procedure P4 (reflow process), the reflow machine 40 is used to melt the paste-like solder printed on the lands R1, R2, R3 and the discrimination land R. Then, by gradually cooling and solidifying the melted solder, the electronic components are electrically connected to the lands R1, R2, and R3 by solder. At this time, the paste-like solder printed on the discrimination land R is also melted and then solidified.

  In a subsequent fifth procedure P5 (appearance inspection step), image data of the solder portion is acquired using the camera 51 (see FIG. 9) of the appearance inspection machine 50. This image data will be described in detail later with reference to FIGS. In a subsequent sixth procedure P6, the analysis device 52 (see FIG. 9) of the visual inspection machine 50 is used to determine whether the soldering state is good or not based on the acquired image data, and whether the solder type is abnormal. judge.

  If the analysis device 52 determines that the circuit is normal, the subsequent seventh procedure P7 uses the electrical inspection device 60 to check whether the circuit operates normally. In the following eighth procedure P8, the worker carries out the printed circuit boards A6 and B6 that have passed the inspection of the electrical inspection device 60 as normal products from the production lines LA and LB. On the other hand, when the analyzer 52 determines that there is an abnormality, in the ninth procedure P9, the worker H makes an emergency stop on the production line determined to be abnormal.

  Next, a method for determining the solder type by the appearance inspection machine 50 will be described.

  FIG. 4 is a front view showing a state in which the paste-like lead solder Sp is printed on the discrimination land R before the reflow. A predetermined gap (slit SL) is formed in the center of the lead solder Sp. In other words, the paste lead solder Sp is separated into the first portion Sp1 and the second portion Sp2 by the slit SL so as not to contact each other.

  In the state before reflow, the appearance is the same regardless of whether lead-free solder or lead solder is used. That is, also in the lead-free solder Sf, the slit SL is formed in the center of the lead-free solder Sf as in FIG. In other words, the lead-free solder Sf is separated into the first part Sf1 and the second part Sf2 by the slit SL so as not to contact each other.

  When the solders Sp and Sf printed in this way are melted in the reflow process, the wettability is exhibited and the solder Sp and Sf spread on the discrimination land R. However, since the lead-free solder Sf has lower wettability than the lead solder Sp, the area that expands when melted is small. Therefore, in the case of the lead solder Sp, as shown in FIG. 5, the slit SL is filled with the lead solder Sp, and the slit SL disappears. That is, the separated first portion Sp1 and second portion Sp2 are connected.

  On the other hand, in the case of the lead-free solder Sf, the slit SL is not filled with the lead-free solder Sf as shown in FIG. 6, and the slit SL remains. That is, the separated first portion Sf1 and second portion Sf2 are maintained at least partially separated. In the example of FIG. 6, the entire first portion Sf1 and second portion Sf2 remain separated, but the first portion Sf1 and the second portion Sf2 are partially connected in a portion other than the central portion of the slit SL. There may be cases.

  Note that the solder Sp and Sf do not protrude from the discrimination land R during the reflow due to the surface tension, and the solder Sp and Sf rise on the discrimination land R as shown in FIGS. However, in the case of the lead solder Sp, the first part Sp1 and the second part Sp2 are raised together (see FIG. 7). On the other hand, in the case of the lead-free solder Sf, each of the first portion Sf1 and the second portion Sf2 is raised with the first portion Sf1 and the second portion Sf2 separated (see FIG. 8).

  Next, a method for inspecting the appearance of the solder S of the electronic component 130 will be described with reference to FIGS. This appearance inspection is performed by the appearance inspection machine 50 to inspect whether the solder joint is good or not and whether there is a short circuit due to the solder bridge. As shown in FIG. 9, the appearance inspection machine 50 includes an illumination device, a camera 51, and an analysis device 52. The illumination device includes a plurality of light sources 50R, 50G, and 50B that emit light of different colors. These light sources 50R, 50G, and 50B have ring-shaped light emitting surfaces, and each emits light in red, green, and blue. Light emitted from the light sources 50R, 50G, and 50B toward the printed wiring board 12 is reflected by the solder S portion and enters the camera 51 located at the center of the ring-shaped light emitting surface.

  The emission angles from the light sources 50R, 50G, 50B are different for each of the light sources 50R, 50G, 50B. Therefore, for example, when the angle at which the emitted light from the light sources 50R, 50G, and 50B is reflected by the solder S (reflection angle θ) is within a predetermined range, the reflected light is incident on the camera 51 and is detected and detected as image data. Will be. For example, 5 ° to 15 ° (see FIG. 10) for red light, 15 ° to 25 ° (see FIG. 11) for green light, and 25 ° to 38 ° (see FIG. 12) for blue light. Reference) corresponds to the predetermined range.

  Therefore, of the fillet portion of the solder S, the portion indicated by reference numeral S1 in FIG. 13 is mainly blue reflected light, the portion indicated by reference numeral S2 is mainly green reflected light, and the portion indicated by reference numeral S3 is mainly red. Reflected light enters the camera 51. Therefore, as shown in FIG. 14, a color distribution corresponding to the shape of the solder S appears in the image I photographed by the camera 51. For example, the image I includes a blue region I1, a green region I2, and a red region I3, and corresponds to portions indicated by reference numerals S1, S2, and S3 in FIG.

  The vertical axis in FIG. 15 indicates the brightness, and each of the symbols R, G, and B indicates the brightness for red light, green light, and blue light. The horizontal axis (X-axis) in FIG. 15 indicates the position in the X-axis direction in FIGS. 13 and 14. In short, FIG. 15 shows the brightness distribution in the X-axis direction of red light, green light, and blue light at predetermined positions in the Y-axis direction in FIGS.

  Based on the video signal output from the camera 51, the analysis device 52 generates image data having a color distribution shown in FIG. Further, the analysis device 52 analyzes (binarization processing) whether the color whose brightness is equal to or higher than the threshold value TH is red, green, or blue. For example, as indicated by the alternate long and short dash line in FIG. 15, the region indicated by arrow B in the X-axis direction is analyzed as blue, the region indicated by arrow G is green, and the region indicated by arrow R is red. .

  FIG. 14 shows the color distribution of the solder S having a normal shape, while FIG. 16 shows the color distribution showing the shape when the solder S is not joined to the component. The analysis device 52 determines whether the shape is normal based on the color distribution. For example, as shown in FIG. 15, when a color distribution in which a blue region B, a green region G, and a red region R appear alternately appears over the entire area of the solder S in the Y-axis direction, it is determined that the shape is normal. To do.

  On the other hand, in the case of the shape shown in FIG. 16, although the color distribution that appears alternately appears at the center portion in the Y-axis direction, the blue region I1 does not appear at both end portions in the Y-axis direction. In this case, it is determined that the shape is abnormal. As described above, the appearance inspection machine 50 determines whether the soldering state is acceptable based on the color distribution.

  Further, the appearance inspection machine 50 detects the color distribution of the solders Sp and Sf provided on the discrimination land R, and determines whether or not the solder type is abnormal based on the detection result as follows. The shooting range by the camera 51 is set to a position in the discrimination land R where the slit SL exists before reflow. Specifically, the central portion of the discrimination land R indicated by the alternate long and short dash line in FIGS. 5 to 8 is the imaging range Wi.

  As described above with reference to FIG. 7, when the solder provided on the discrimination land R is lead solder Sp, the slit SL disappears after reflow. When the lead solder Sp shown in FIG. 7 is irradiated with light from the light sources 50R, 50G, and 50B, the light reflected in the direction perpendicular to the printed wiring board 12 has the distribution shown in FIG. That is, in the lead solder Sp, the region indicated by the symbol Sr is mainly red, and the region indicated by the symbol Sg is mainly green.

  When the solder provided on the discrimination land R is lead-free solder Sf, the slit SL exists even after reflow as described above with reference to FIG. When the lead-free solder Sf shown in FIG. 8 is irradiated with light from the light sources 50R, 50G, and 50B, the light reflected in the direction perpendicular to the printed wiring board 12 has the distribution shown in FIG. That is, in the lead-free solder Sf, the region indicated by the symbol Sr is mainly red, the region indicated by the symbol Sg is mainly green, and the region indicated by the symbol Sb is mainly blue.

  In the case of the lead solder Sp, the color distribution in the central portion (shooting range Wi) of the discrimination land R is only red as shown in FIGS. On the other hand, in the case of the lead-free solder Sf, the color distribution in the central portion of the discrimination land R is red, green, blue, red, blue, green, in the X-axis direction as shown in FIGS. Different color regions appear alternately in the order of red. 19 and FIG. 20, the vertical axis indicates the lightness, and each of the symbols R, G, and B indicates the lightness for red light, green light, and blue light. The horizontal axis (X axis) in FIGS. 19 and 20 indicates the position in the X axis direction in FIGS. 17 and 18. In short, FIGS. 19 and 20 show the lightness distribution in the X-axis direction of red light, green light, and blue light at the position of the imaging range Wi in FIGS. 17 and 18.

  Based on the video signal output from the camera 51, the analysis device 52 generates image data having the color distribution shown in FIGS. Further, the analysis device 52 analyzes (binarization processing) whether the color whose brightness is equal to or higher than the threshold value TH is red, green, or blue. For example, in the case of the color distribution of the lead solder Sp shown in FIG. 17, the entire photographing range Wi is a red region and is binarized to red.

  On the other hand, in the case of the color distribution of the lead-free solder Sf shown in FIG. 18, as shown in FIG. 21, red, green, blue, red, blue, green, and red regions are alternately arranged in the X-axis direction of the imaging range Wi. Appears in Therefore, when regions of different colors appear alternately, it can be determined that the type of solder is lead-free solder Sf. On the other hand, when the same color region appears continuously, it can be determined that the solder type is lead solder Sp.

  Such determination processing is performed by a microcomputer (microcomputer 52a) included in the analysis device 52. That is, the microcomputer 52a first reads the image data illustrated in FIGS. 19 and 20 based on the image of the discrimination land R photographed by the camera 51 in step S51 in FIG. In the subsequent step S22, it is analyzed (binarization processing) whether the color whose brightness is equal to or higher than the threshold value TH at each position in the X-axis direction in the read image data (binarization processing). To do.

  In a succeeding step S53, it is determined whether or not the analyzed color distribution has continuity. That is, when the same color is continuously distributed in the X-axis direction, it is determined that there is continuity. If it is determined that there is continuity, it is determined in step S54 that the lead solder Sp is used. On the other hand, if it is determined that there is no continuity, it is determined in step S55 that the lead-free solder Sf is used.

  In subsequent step S56, it is determined whether or not the solder type determined in steps S54 and S55 is normal. For example, the microcomputer 52a of the visual inspection machine 50 installed in the lead-free solder production line LB determines that it is normal when it is determined as lead-free solder Sf, and when it is determined as lead solder Sp. Determines that no regular solder is used. If it is determined that regular solder is not used, an abnormal signal is output to the integrated management device 70 in the subsequent step S57.

  Thereby, when the regular solder is not used, the integrated management apparatus 70 can notify the worker H to that effect, and as a result, measures such as an emergency stop of the corresponding production line can be implemented.

  As described above, according to the solder discrimination method according to the present embodiment, the slits SL are provided in the paste-like solders Sf and Sp applied to the discrimination land R, and the type of solder is determined based on the presence or absence of the slit SL after reflow. Determine. Specifically, if the slit SL is present, the lead-free solder Sf is determined, and if the slit SL is not present, the lead solder Sp is determined.

  For this reason, it is not necessary to measure the solder spreading area as in the prior art, and it is possible to discriminate the solder type by inspecting the appearance of the presence of the slit SL, so that the discrimination can be realized with high accuracy. Further, since the above determination is made at the time of the appearance inspection process, the solder type abnormality can be detected at an early stage in each process of the production lines LA and LB. Therefore, it is possible to stop early that the printed circuit boards are successively manufactured with the wrong type of solder in the second procedure P2 (application process).

  Furthermore, according to the present embodiment, in the second procedure P2 (coating process) shown in FIG. 3, the slits SL are provided so that the first portions Sp1, Sf1 and the second portions Sp2, Sf2 are separated without contacting each other. Yes.

  Here, contrary to the present embodiment, when the first part Sf1 and the second part Sf2 of the lead-free solder Sf are in a shape of partial contact (see FIG. 25), the following problem occurs. That is, even if the slit SL actually exists after the reflow, when the appearance inspection is performed after the reflow at the portion where the first portion Sf1 and the second portion Sf2 are partially in contact before the reflow, the slit SL The result is that there is no data. Then, in spite of the fact that lead-free solder Sf is actually used, there is a possibility that it is erroneously determined that lead solder Sp is used. On the other hand, in the present embodiment, since the first portions Sp1 and Sf1 and the second portions Sp2 and Sf2 are separated from each other without being in contact with each other, the risk of erroneous determination described above can be reduced.

  Furthermore, according to the printed circuit board using the lead-free solder Sf according to the present embodiment, the lead-free solder Sf connected to the discrimination land R is the first part Sf1 and the second part of the lead-free solder Sf. It is a shape having a slit SL between Sf2. Therefore, it can be confirmed that the lead-free solder Sf is normally used by confirming that the slit SL exists. Therefore, after the printed circuit board is carried out from the production line LB for lead-free solder, it can be easily confirmed whether or not the lead-free solder Sf is normally used on the printed circuit board.

  Furthermore, according to the present embodiment, the lead-free solder Sf connected to the discrimination land R has a shape in which a slit SL is provided so that the first portion Sf1 and the second portion Sf2 are separated without contacting each other. . In other words, the width of the slit SL is set so that the first portion Sf1 and the second portion Sf2 are separated without contacting each other even after reflow.

  Here, contrary to the present embodiment, when the first portion Sf1 and the second portion Sf2 have a shape that partially contacts after reflow (see FIG. 25), the following problem occurs. That is, even if the slit SL actually exists after reflow, when the appearance inspection is performed on the portion where the first portion Sf1 and the second portion Sf2 are partially in contact, the slit SL is not present. It becomes a test result. Then, in spite of the fact that lead-free solder Sf is actually used, there is a possibility that it is erroneously determined that lead solder Sp is used. On the other hand, in the present embodiment, since the first parts Sp1, Sf1 and the second parts Sp2, Sf2 are separated from each other without being in contact with each other after the reflow, the above-described possibility of erroneous determination can be reduced.

(Second Embodiment)
In the first embodiment, as shown in FIGS. 5 and 6, one central portion of the discrimination land R is set as the imaging range Wi. On the other hand, in the present embodiment, as shown by the one-dot chain line in FIGS. 23 and 24, a plurality of locations of the discrimination land R are set as the imaging range Wi. The plurality of shooting ranges Wi are arranged side by side in the direction in which the slit SL extends.

  The appearance inspection machine 50 determines whether or not different color regions appear alternately for each of the plurality of imaging ranges Wi in the same manner as in the first embodiment. Then, based on each determination result, the type of solder is determined. For example, when different color regions appear alternately in all of the plurality of imaging ranges Wi, it is determined that the slit SL is present and the lead-free solder Sf is determined. Alternatively, when different color regions appear alternately in at least one of the plurality of imaging ranges Wi, it is determined that the slit SL exists and the lead-free solder Sf is determined. As described above, according to the present embodiment, since the type of solder is determined based on the results of a plurality of shooting ranges Wi, the accuracy of the determination is improved.

(Third embodiment)
In the first embodiment, as shown in FIG. 4, the slits SL (gap) are provided so that the first portions Sf1 and Sp1 and the second portions Sf2 and Sp2 are separated without contacting each other. On the other hand, in the present embodiment, while the gap SLa is provided between the first portions Sf1 and Sp1 and the second portions Sf2 and Sp2, as shown in FIG. 25, a part of the first portions Sf1 and Sp1 is the second portion. It is in a state connected to a part of the portions Sf2 and Sp2.

  Even if the gap SLa has such a shape, the gap SLa disappears as shown in FIG. 26 when the lead solder Sp is used after reflow, and FIG. 27 shows the case when the lead-free solder Sf is used. As shown, the gap SLa remains. Therefore, also in the present embodiment, similar to the first embodiment, the type of solder can be determined by inspecting the presence or absence of the gap SLa after reflow.

(Fourth embodiment)
In the embodiment shown in FIG. 1, a discrimination land R is provided on a printed wiring board 12 mounted on a meter device 10 as a final product. On the other hand, in this embodiment, the discrimination land R is provided in the non-product area 122 described below in the printed wiring board 120 in the manufacturing process (see FIG. 28).

  A printed wiring board 120 shown in FIG. 28 is in a manufacturing process, and includes a product region 121 that is a portion mounted on a final product, and a non-product region 122 that is cut and removed from the printed wiring board 120. . A product region 121 having a shape corresponding to the shape of the final product to be mounted is cut out from the rectangular printed wiring board 120. Specifically, the product area 121 and the non-product area 122 included in the printed wiring board 120 are connected by a plurality of connecting portions 120a. By cutting these connecting portions 120a, the product area 121 is printed wiring. Cut from the plate 120. That is, the non-product region 122 located around the product region 121 is cut and removed.

  In the embodiment shown in FIG. 2, the printed wiring board 12 in the product area from which the non-product area is removed is carried into the production lines LA and LB. That is, the reflow process is performed after the cutting and removing process for removing the non-product region. On the other hand, in this embodiment, the reflow process and the appearance inspection process are performed before the cutting and removing process. A discrimination land R is provided in the non-product region 122, and the lead-free solder Sf or the lead solder Sp is provided in the discrimination land R with the slit SL in the same manner as in FIG. Yes. Note that electronic parts are not mounted in the non-product area 122.

  As described above, according to the present embodiment, the type of solder can be determined by inspecting the presence or absence of the slit SL after reflowing in the same manner as in the first embodiment. In addition, since the discrimination land R is provided in the non-product area 122 in the present embodiment, it is unnecessary to provide the discrimination land R in the product area 121. Therefore, it is possible to avoid the degree of freedom of the layout of electronic components mounted on the product area 121 from being reduced by the determination land R.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as illustrated below. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

  In the embodiment shown in FIG. 2, the production lines LA and LB are configured so that the worker H is manually operated so as to immediately stop the corresponding production line when notified of the solder type abnormality. On the other hand, the production lines LA and LB may be automatically stopped when the solder type abnormality is notified. Such automatic stop control may be performed by, for example, the visual inspection machine 50 or the integrated management device 70.

  In each of the above-described embodiments, the appearance of the slit SL is inspected using the appearance inspection machine 50. In contrast, an operator may visually inspect the presence or absence of the slit SL.

  DESCRIPTION OF SYMBOLS 12, 120 ... Printed wiring board, 13 ... Microcomputer (electronic component), 14 ... Motor (electronic component), 15 ... Connector (electronic component), P1 ... 1st procedure (land formation process), P2 ... 2nd procedure (application | coating) Process), P4 ... 4th procedure (reflow process), P5 ... 5th procedure (appearance inspection process), Sf ... lead-free solder, Sp ... lead solder, Sp1, Sf1 ... first part of solder, Sp2, Sf2 ... solder SL ... slit (gap), SLa ... gap, R ... discrimination land, R1, R2, R3 ... land.

Claims (5)

A solder discrimination method for discriminating whether a solder applied to a printed wiring board (12, 120) is a lead-free solder (Sf) or a lead solder (Sp),
In manufacturing the printed wiring board (12) by forming the lands on the insulating substrate, the dummy discrimination lands (R1, R2, R3) are separated from the lands (R1, R2, R3) on which the electronic components (13, 14, 15) are mounted. A land forming step (P1) for forming R);
An application step (P2) of applying paste solder (S, Sf, Sp) to the land and the discrimination land;
A reflow step (P4) of heating and melting the paste-like solder;
An appearance inspection step (P5) for inspecting the appearance of the solder solidified after melting;
With
In the applying step, when applying the paste-like solder to the discrimination land, a predetermined gap (SL, SLa) is provided between the first portion (Sp1, Sf1) and the second portion (Sp2, Sf2) of the solder. ) To form,
In the appearance inspection step, an appearance inspection is performed to determine whether or not the gap exists in the solder after reflow. When the inspection result indicates that the gap exists, it is determined that the solder is lead-free solder, and the gap exists. A solder discriminating method characterized by discriminating that it is lead solder when it is an inspection result indicating that it is not.   2. The solder discrimination method according to claim 1, wherein in the coating step, the gap (SL) is provided so that the first portion and the second portion are separated without contacting each other. The printed wiring board (120) in the reflow process has a product area (121) on which electronic components are mounted and a non-product area (122) around the product area where the electronic components are not mounted. ) Exists,
After the reflow step, the cutting and removing step of cutting and removing the non-product area from the printed wiring board,
The solder discrimination method according to claim 1 or 2, wherein, in the land formation step, the discrimination land is formed in the non-product area. A printed circuit board comprising a printed wiring board (12) and electronic components (13, 14, 15) mounted on lands (R1, R2, R3) of the printed wiring board,
The printed wiring board has a dummy discrimination land (R) on which the electronic component is not mounted separately from the land.
Lead-free solder (S, Sf) is connected to the land and the discrimination land by a reflow method,
The lead-free solder connected to the discrimination land has a shape having a predetermined gap (SL, SLa) between the first part (Sf1) and the second part (Sf2) of the lead-free solder. Printed circuit board.   The lead-free solder connected to the discrimination land has a shape in which the gap (SL) is provided so that the first part and the second part are separated without contacting each other. Item 5. The printed circuit board according to Item 4.

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