Solder jet evaluation device and evaluation system

Abstract

To evaluate a state of solder jet flow stably.SOLUTION: An evaluation device (200) has a thin plate member (201) attached to a transported member which is transported on a conveyer (104). In the evaluation device (200), in order to evaluate the state of a solder jet flow (110) of a soldering device, while the thin plate (201) is being transported above a molten solder bath (102) by the conveyor (104), the temperature distribution of the thin plate (201) which is in contact with the solder jet flow (110) is measured by an infrared camera (107). The thin plate member (201) is made of a material and a plate thickness such that the biot number is 0.1 or smaller.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a solder jet evaluation device and evaluation system. [Background technology]

[0002] Equipment that uses a jet of molten solder to solder electronic components to printed circuit boards is commonly used on manufacturing lines. In such soldering equipment, the contact state of the solder jet with the printed circuit board on which the electronic components are mounted affects the soldering quality. Therefore, in order to avoid the occurrence of defective products, it is necessary to properly evaluate the state of the solder jet when manufacturing printed circuit boards.

[0003] For example, Japanese Patent Laid-Open Publication No. 10-193092 (Patent Document 1) describes a solder jet control device that jets molten solder upward from a nozzle in a solder bath and photographs the contact state between the solder jet and a plate-like member while the jetted solder is in contact with a plate-like member placed above the nozzle. Furthermore, in Patent Document 1, the photographed image is subjected to signal processing to detect the contact width between the solder jet and the plate-like member, and the rotation speed of a solder jet pump is controlled to stabilize the detected contact width. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-193092 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the plate-shaped member is made of heat-resistant glass or heat-resistant resin. When heat-resistant glass is used, an image of the solder jet and the contact of the plate-shaped member is taken by a CCD (Charge Coupled Device) camera, and when heat-resistant resin is used, an image is taken by an infrared camera.

[0006] However, when the contact state between the heat-resistant glass plate and the solder jet is photographed by a CCD camera, partial halation occurs in the photographed image, which may make it difficult to evaluate the contact state between the heat-resistant glass plate and the solder jet by image processing. Specifically, partial halation is caused by the presence of air bubbles due to the flux and spaces due to the three-dimensional undulating shape of the solder jet between the heat-resistant glass plate and the solder jet.

[0007] On the other hand, when the contact state between the heat-resistant resin and the solder jet is photographed by an infrared camera, there is a concern that a time loss occurs before the temperature distribution on the image photographed by the infrared camera shows the contact area between the heat-resistant resin and the solder jet due to the large thermal resistance of the heat-resistant resin. As a result, there is a concern that it may become difficult to evaluate the contact state between the heat-resistant resin and the solder jet by image processing.

[0008] The present disclosure has been made to solve these problems, and an object of the present disclosure is to provide an evaluation device and evaluation method that can stably evaluate the state of a solder jet, as well as to provide a stable manufacturing method for printed circuit boards that avoids soldering defects. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, there is provided an evaluation device for a solder jet used in a soldering apparatus, the soldering apparatus including a molten solder bath from which a solder jet is ejected, a transport conveyor for transporting an object to be soldered so as to pass above the molten solder bath, and a temperature distribution measuring device for an object passing above the molten solder bath. The evaluation device includes a transport member and a thin plate member transported on the transport conveyor. The thin plate member is attached to the transport member at a position above the molten solder bath where it comes into contact with the solder jet. The thin plate member is configured such that, when it comes into contact with the solder jet, the rate of heat transfer by thermal conduction within the thin plate member is higher than the rate of heat transfer by heat transfer from the solder jet to the thin plate member.

[0010] According to another aspect of the present disclosure, a method for evaluating a solder jet includes the steps of: obtaining a thermal image showing the temperature distribution within the surface of the thin plate member by measuring the thin plate member with a temperature distribution measuring device as an evaluation device according to the present disclosure passes above a bath of molten solder; and determining whether the state of the solder jet is good or bad based on the state of the temperature distribution within the surface obtained by image processing of the thermal image.

[0011] According to yet another aspect of the present disclosure, a method for manufacturing a printed circuit board includes a step of evaluating a solder jet of a soldering device by the solder jet evaluation method according to the present disclosure, and a soldering step of passing a printed circuit board above a molten solder bath of the soldering device by a transfer conveyor. The soldering step is performed after the quality of the solder jet is determined by the evaluation step. Effect of the Invention

[0012] According to the present disclosure, an evaluation device and evaluation method are provided that can stably evaluate the state of a solder jet based on the temperature distribution in a horizontal plane of a thin plate member or a solder jet measured by a temperature distribution measuring device, and a stable manufacturing method for printed circuit boards that avoids soldering defects by providing a soldering process after the evaluation can be provided. [Brief description of the drawings]

[0013] [Figure 1] 1 is a conceptual perspective view illustrating a configuration of a soldering apparatus to be evaluated by a solder jet evaluation apparatus according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 13 is a conceptual perspective view for explaining the operation during an evaluation test of a solder jet according to the present embodiment. [Diagram 3] FIG. 13 is a block diagram illustrating an example of a configuration for image processing in an evaluation test of a solder jet according to the present embodiment. [Figure 4A] FIG. 3 is a perspective view illustrating a configuration example of the evaluation device shown in FIG. 2. [Figure 4B] FIG. 4B is an exploded view of the evaluation device shown in FIG. 4A. [Figure 4C] 3 is a plan view illustrating an example of the configuration of the evaluation device shown in FIG. 2. [Diagram 5] 1 is a graph showing an example of the relationship between the material and thickness of a thin plate and the Biot number. [Figure 6A] FIG. 2 is a conceptual first cross-sectional view of a thin sheet in contact with a solder jet. [Figure 6B] FIG. 13 is a conceptual second cross-sectional view of the thin plate in contact with the solder jet. [Figure 7] FIG. 13 is a perspective view showing a first modified example of the configuration of a conveying member. [Figure 8] FIG. 11 is a perspective view showing a second modified example of the configuration of the conveying member. [Figure 9A] FIG. 2 is a first conceptual diagram illustrating an evaluation test performed by the solder jet evaluation device according to the first embodiment. [Figure 9B] 6 is a second conceptual diagram illustrating an evaluation test using the solder jet evaluation device according to the first embodiment. FIG. [Figure 9C] FIG. 9C is a conceptual diagram illustrating the temperature distribution in a thermal image obtained in the state of FIGS. 9A and 9B. [Figure 10] 13 is a conceptual diagram illustrating an example of processing a thermal image obtained in an evaluation test of a solder jet according to the second embodiment. FIG. [Figure 11] FIG. 13 is a conceptual diagram illustrating an example of setting an inspection frame within a processed thermal image. [Figure 12] FIG. 13 is a conceptual diagram illustrating an example of setting quantitative parameter values ​​for evaluating the state of a secondary jet. [Figure 13] 11A and 11B are conceptual diagrams for explaining examples of defective determination from thermal images. [Figure 14] FIG. 2 is a conceptual perspective view of a soldering device to be evaluated. [Figure 15] 15 is a cross-sectional view of FIG. 14 when the solder jet is normal. FIG. [Figure 16] 16 is a first cross-sectional view taken at the same position as FIG. 15 for explaining the cause of an abnormality in solder jet. [Figure 17] 16 is a second cross-sectional view taken at the same position as FIG. 15 for explaining the cause of an abnormality in solder jet. [Figure 18]16 is a third cross-sectional view taken at the same position as FIG. 15 for explaining the cause of an abnormality in solder jet. [Figure 19] 11 is a flowchart illustrating a method for evaluating a solder jet and a method for manufacturing a printed circuit board according to a third embodiment. [Figure 20] 13 is a conceptual diagram illustrating an example of an evaluation model used in the method for evaluating a solder jet according to the third embodiment. FIG. [Figure 21] 13 is a conceptual diagram illustrating an example of regression prediction by the solder jet evaluation method according to the third embodiment. FIG. [Figure 22A] 10 is a conceptual cross-sectional view illustrating a first example of the shape of a solder jet in a vertical cross section in the transfer direction. FIG. [Figure 22B] 13 is a conceptual cross-sectional view for explaining a second example of the shape of a solder jet in a vertical cross section in the transfer direction. FIG. [Figure 22C] 13 is a conceptual cross-sectional view for explaining a third example of the shape of a solder jet in a vertical cross section in the transfer direction. FIG. [Figure 23A] 1A is a conceptual cross-sectional view for explaining a first example of a cross-sectional shape of a solder jet when a printed circuit board is not passing through. FIG. [Figure 23B] 23B is a conceptual cross-sectional view for explaining a contact state between the solder jet and the printed circuit board shown in FIG. 23A. [Figure 24A] 11 is a conceptual cross-sectional view for explaining a second example of the cross-sectional shape of a solder jet when a printed circuit board is not passing through. FIG. [Figure 24B] 24B is a conceptual cross-sectional view for explaining a contact state between the solder jet and the printed circuit board shown in FIG. 24A. [Figure 25A] FIG. 1 shows a first example of a thermal image of a solder jet and the corresponding cross-sectional profile. [Figure 25B] FIG. 13 shows a second example of a thermal image of a solder jet and the corresponding cross-sectional profile. [Figure 26] 1A and 1B are conceptual cross-sectional views illustrating the relationship between the cross-sectional shape of a solder jet and the radiant energy to an infrared camera. [Figure 27]1A and 1B are conceptual cross-sectional views illustrating the relationship between the cross-sectional shape of a solder jet and the temperature detected by an infrared camera. [Figure 28] 10 is a conceptual cross-sectional view illustrating the relationship between the flow rate of a solder jet and the temperature detected by an infrared camera. [Figure 29A] 4 is a thermal image and a graph illustrating an example of a temperature distribution of a primary jet in a normal state. [Figure 29B] 11 is a thermal image and a graph illustrating an example of an abnormal temperature distribution of a primary jet. [Figure 30A] FIG. 13 is a conceptual diagram illustrating an example of monitoring a primary jet using an inspection frame. [Figure 30B] FIG. 13 is a conceptual diagram illustrating an example of monitoring a secondary jet using an inspection frame. [Diagram 31] 13 is a flowchart illustrating a method for evaluating a solder jet and a method for manufacturing a printed circuit board according to a fourth embodiment. [Diagram 32] 13 is a flowchart illustrating a method for evaluating a solder jet according to a modified example of the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Although several embodiments will be described below, it is planned from the beginning of the application that the configurations described in each embodiment will be appropriately combined. In the following, the same or corresponding parts in the drawings will be given the same reference numerals, and the description thereof will not be repeated in principle.

[0015] Embodiment 1 FIG. 1 is a conceptual perspective view illustrating the configuration of a soldering apparatus to be evaluated by an apparatus for evaluating a solder jet according to the present embodiment.

[0016] Referring to FIG. 1, soldering apparatus 100 includes a housing 101, a molten solder bath 102 arranged inside housing 101, a transport conveyor 104, a preheating device 106, and an infrared camera 107.

[0017] The molten solder bath 102 is provided with a motor 108 that drives an impeller that causes the molten solder to flow. When the motor 108 causes the molten solder to flow, a solder jet is generated from the molten solder bath 102 toward the upper part.

[0018] The transport conveyor 104 transports a printed circuit board 103, which is shown as a representative example of an object to be soldered, inside the preheating device 106 and above the molten solder bath 102. The preheating device 106 includes a preheater 105. The preheater 105 heats the printed circuit board 103 before soldering in the molten solder bath 102. When the printed circuit board 103 passes above the molten solder bath 102 by the transport conveyor 104, the printed circuit board 103 comes into contact with a solder jet, and components at the contact locations are soldered.

[0019] The infrared camera 107 is provided as one example of a "temperature distribution measuring instrument" having the function of measuring or monitoring the temperature distribution within a specified field of view, including inside an object passing over the molten solder bath 102 and directed from above the molten solder bath 102 toward the transport conveyor 104 and the molten solder bath 102.

[0020] FIG. 2 is a conceptual perspective view for explaining the operation during an evaluation test of a solder jet according to this embodiment.

[0021] 2, during a solder jet evaluation test, a solder jet evaluation device 200 is carried by a carrying conveyor 104 in place of the printed circuit board 103 in the soldering apparatus 100 shown in FIG.

[0022] FIG. 2 shows a timing when the evaluation device 200 passes over the molten solder bath 102. At this timing, the solder jet 110 ejected from the molten solder bath 102 is partially in contact with the thin plate 201 of the evaluation device 200. At this timing, the thin plate 201 in contact with the solder jet 110 is photographed from above by the infrared camera 107, thereby acquiring an image (hereinafter also referred to as a "thermal image") showing the temperature distribution in the surface (planar direction) of the thin plate 201. For example, the infrared camera 107 photographs a plurality of sheets of the thin plate 201 in succession while the thin plate 201 is being transported at a predetermined constant speed. Furthermore, a display unit 109 for displaying the thermal image is provided. The display unit 109 is composed of a liquid crystal display or the like, and has a function of displaying information based on the image photographed by the infrared camera 107.

[0023] In this embodiment, solder jet 110 is composed of primary jet 111 and secondary jet 112. Primary jet 111 has an uneven shape because it is jetted from a multi-hole jet port. In contrast, secondary jet 112 has a uniform surface shape because it is jetted from a single large opening jet port.

[0024] In this embodiment, the state of solder jet 110 is evaluated by image processing using a thermal image taken by infrared camera 107. Note that it is also possible to realize the function of the "temperature distribution measuring instrument" by a device other than infrared camera 107, as long as it is possible to obtain a similar thermal image.

[0025] FIG. 3 shows a block diagram illustrating an example of a configuration for image processing in an evaluation test of a solder jet according to this embodiment.

[0026] 3, thermal imaging data (e.g., data showing temperature measurement values ​​for each of a plurality of pixels constituting the thermal image) constituting the thermal image captured by the infrared camera 107 is input to the controller 300. The thermal image captured by the infrared camera 107 can be directly displayed on the display unit 109 in a visually recognizable manner (e.g., in a manner in which the display color differs according to the detected temperature corresponding to each pixel).

[0027] The controller 300 can be configured as, for example, one function of a personal computer. Alternatively, although the controller 300 and the infrared camera 107 are depicted as separate devices in Fig. 3, the controller 300 can also be configured by a microcomputer or the like built into the infrared camera 107.

[0028] The controller 300 includes an A / D (Analog to Digital) converter 310 and a D / A (Digital to Analog) converter 340 as an interface with the outside, a memory 320, a CPU (Central Processing Unit) 330, and a bus 350 as a data transmission path.

[0029] The A / D converter 310, memory 320, CPU 330, and D / A converter 340 can exchange data and signals with each other via a bus 350. The memory 320 includes a ROM (Read Only Memory) and a RAM (Random Access Memory), etc. For example, the memory 320 stores a program for executing an evaluation test of the solder jet according to this embodiment and data used by the program. Alternatively, the memory 320 can store calculated data (various parameter values, judgment results, processed image data, etc.) obtained as a result of the evaluation test.

[0030] D / A converter 340 converts a digital signal indicating the calculation data calculated by CPU 320 into an analog voltage signal and outputs it to the outside of controller 300. As a result, the calculation data is supplied to an external device of controller 300 as output data of controller 300. For example, display unit 109 can display various parameter values, judgment results, and images (including images after processing) obtained by an evaluation test of solder jet 110 in response to the output signal of controller 300.

[0031] Next, a configuration example of the evaluation device 200 shown in FIG. 2 will be described with reference to FIGS. 4A to 4C. 4A shows a perspective view of the evaluation device 200 when it is assembled. The evaluation device 200 is constructed by attaching a thin plate member (hereinafter, simply referred to as a “thin plate”) 201 to a conveying member 210.

[0032] FIG. 4B shows a development view of FIG. 4A for explaining a configuration example of the conveying member 210, and FIG. 4C shows a plan view of the evaluation device 200 as seen from above.

[0033] The conveying member 210 has an upper jig 211, a lower jig 212, a spacer 213, and a knurled screw 214, a positioning pin 215, and a hexagon socket bolt 216 as "fixing members".

[0034] The lower jig 212 has a rectangular shape, and the upper jig 211 has a so-called "U" shape with an opening on the rear side in the conveying direction on the transport conveyor 104. The thin plate 201 is attached to a first side 212a of two opposing sides of the lower jig 212. That is, in the surface direction of the thin plate 201, a space 219 is provided between the thin plate 201 and a second side 212b of the two sides. The first side 212a is transported in the conveying direction on the transport conveyor 104 ahead of the second side 212b.

[0035] The positional relationship between the upper jig 211, the lower jig 212, and the spacer 213 is determined by two positioning pins 215. The thin plate 201 is placed in a space formed by the spacer 213 between the upper jig 211 and the lower jig 212. The thin plate 201 is fixed to the lower jig 212 (first side 212a) by one knurled screw 214. Furthermore, the upper jig 211, the lower jig 212, and the spacer 213 are fastened together by nine hexagon socket bolts 216 without the thin plate 201 being interposed therebetween.

[0036] The thickness of the spacer 213 is greater than the thickness of the thin plate 201, and the thin plate 201 is fixed to the lower jig 212 while being positioned between the upper jig 211 so as to provide a gap (corresponding to the "first gap") in the thickness direction of the thin plate 201 to allow for thermal expansion of the thin plate 201.

[0037] 4C, the thin plate 201 is disposed in a positional relationship with respect to the spacer 213 such that a gap 217 is formed between the thin plate 201 and the spacer 213 even in the in-plane direction of the thin plate 201. That is, the thin plate 201 is fixed to the lower jig 212 (first side 212a) by a knurled screw 214 penetrating the upper jig 211 in a state where the thin plate 201 is placed on the lower jig 212 in a positional relationship such that a gap 217 is formed between the thin plate 201 and the spacer 213.

[0038] The length (in the surface direction) of gap 217 is designed to be larger than (linear expansion coefficient of thin plate 201) × (temperature difference between the room and the solder jet 101) × (width of thin plate 201). This prevents thin plate 201 from warping, even if thin plate 201 thermally expands upon contact with solder jet 110, by being restrained by spacer 213. Gap 217 corresponds to the "second gap."

[0039] On the other hand, since the conveying member 210 is structured to support the thin plate 201 only at its periphery in order to prevent deformation of the thin plate 201 due to thermal expansion, there is concern that the thin plate 201 may be deflected due to its own weight. For this reason, it is preferable to select a highly rigid material (e.g., tungsten) for the thin plate 201 to reduce the effect of deflection due to its own weight.

[0040] By configuring evaluation device 200 in this way, the only constraint point on thin plate 201 is the point where knurled screw 214 is tightened, so that expansion and contraction of thin plate 201 due to thermal expansion when thin plate 201 comes into contact with solder jet 110 is not restricted. As a result, thin plate 201 can maintain a flat state without warping when in contact with solder jet 110. As a result, the temperature distribution within the surface of thin plate 201 on the thermal image captured by infrared camera 107 can be obtained with high reproducibility as an accurate reflection of the contact area between thin plate 201 and solder jet 110.

[0041] The thin plate 201 is preferably made of a material with high thermal conductivity, and may be made of a tungsten plate with a thickness of 0.2 mm and dimensions of 200 mm width x 200 mm length. The surface of the thin plate 201 (tungsten plate) photographed by the infrared camera 107 is preferably coated with a black body spray to increase the emissivity of the surface. The thin plate 201 is made of a material and dimensions such that the rate of heat transfer by thermal conduction inside the thin plate 201 is higher than the rate of heat transfer by heat transfer from the solder jet 110 to the thin plate 201 when the thin plate 201 comes into contact with the solder jet 110.

[0042] The thickness and material of thin plate 201 can be selected based on the Biot number. The Biot number is generally used as a parameter that indicates the speed of heat transfer in thermal conduction. Since the thickness of thin plate 201 is significantly smaller than the surface size (0.2<<200), in this embodiment, the Biot number can be calculated by (Biot number)=(heat transfer coefficient of solder jet 110)×(plate thickness)÷(thermal conductivity of thin plate 201).

[0043] A Biot number greater than 0.1 means that the transfer of heat by internal thermal conduction tends to be slower than the transfer of heat by thermal conduction of solder jet 110. In this case, a time delay occurs before the state of solder jet 110 appears as a temperature distribution on the surface of thin plate 201 photographed by infrared camera 107. Therefore, in this embodiment, it is preferable to select the material and thickness of thin plate 201 so that the Biot number is 0.1 or less.

[0044] FIG. 5 is a graph showing an example of the relationship between the Biot number and the material and thickness of a thin plate, in which an example of the Biot number is calculated for a tungsten plate and a titanium plate with the plate thickness as a parameter.

[0045] The horizontal and vertical axes of Fig. 5 indicate the plate thickness and Biot number, respectively. Fig. 5 shows characteristics C1 when the thin plate 201 is a titanium plate, and characteristics C2 when it is a tungsten plate. The thermal conductivity of tungsten is 174 [W / m / K], and the thermal conductivity of titanium is 21.9 [W / m / K]. On the other hand, the thermal conductivity of the solder jet 110 is 10,000 [W / m 2 / K].

[0046] 5, it can be seen that with the tungsten plate (C2), the Biot number does not reach 0.1 even when the plate thickness is 1 mm. On the other hand, with the titanium plate (C1), the Biot number exceeds 0.1 when the plate thickness exceeds 0.2 mm. Therefore, when the thin plate 201 is made of a titanium plate, the plate thickness should be set to 0.2 mm or less.

[0047] By making such a selection based on the Biot number, it is possible to adopt metals other than tungsten and titanium (e.g., aluminum, iron, etc.) as the material of the thin plate 201. Alternatively, the thin plate 201 can be made of ceramics such as aluminum nitride and silicon nitride.

[0048] A hole with a diameter of 4 mm is made in thin plate 201 (e.g., a tungsten plate). A knurled screw 214 with a diameter of 3 mm is passed through the hole and fixed to lower jig 212, so that thin plate 201 is connected to conveying member 210 in a link-like manner without being in close contact. The diameter of the hole in thin plate 201 is designed to be larger than the diameter of knurled screw 214. The difference between the diameters is designed so that a gap between the hole and knurled screw 214 does not hinder the thermal expansion of thin plate 201 when it comes into contact with solder jet 110. Specifically, the size of the gap is determined so that thin plate 201 is not deformed by thermal expansion occurring in the surface direction of knurled screw 214.

[0049] In the example of Figures 4A to 4C, only one hole is drilled in thin plate 201, but as long as a gap capable of absorbing the amount of expansion and contraction due to thermal expansion is secured between the fixing knurled screw 214 and the hole in thin plate (tungsten plate) 201, multiple holes may be formed in thin plate (tungsten plate) 201 and thin plate 201 may be connected in a link-like manner to conveying member 210 at multiple points using knurled screws 214.

[0050] On the other hand, the upper jig 211, the lower jig 212, and the spacer 213 can be manufactured by processing a heat-resistant resin obtained by impregnating glass cloth with an epoxy resin. Alternatively, the upper jig 211, the lower jig 212, and the spacer 213 can be made of a heat-resistant resin such as polyether, ether, ketone-based resin, and polyimide-based resin, a metal such as aluminum and stainless steel, or a ceramic such as aluminum oxide, aluminum nitride, and silicon nitride.

[0051] Space 219 between thin plate 201 and second side 212b of lower jig 212, provided on the rear side of thin plate 201 in the transport direction, is required for the purpose of preventing the shape of solder jet 110 from being obstructed.

[0052] 6A and 6B are conceptual cross-sectional views of a thin plate 201 in contact with a solder jet 110. In Fig. 6A and 6B, a cross-sectional view including a VI-VI cross section of the evaluation device 200 depicted in Fig. 4A is shown.

[0053] Figure 6A shows a cross-sectional view of a contact state in which the space 219 is provided in the transport member 210 and the shape of the solder jet 110 is not disturbed, while Figure 6B shows a cross-sectional view of a contact state in which the space 219 is not provided in the transport member 210 and the shape of the solder jet 110 is disturbed.

[0054] 6A and 6B, the lower jig 212 protrudes from the thin plate 201 in the direction (downward) toward the solder jet 110 beyond the thin plate 201. For this reason, in a structure in which the thin plate 201 is attached to the conveying member 210 without providing a space 219 as in Fig. 6B, the shape of the solder jet 110 is disturbed when the thin plate 201 and the solder jet 110 come into contact with each other, i.e., when a thermal image is taken. This raises concerns that it may become difficult to obtain a thermal image that accurately reflects the shape of the solder jet 110.

[0055] 6A , by appropriately ensuring the length W1 of the space 219 along the transport direction with respect to the length WS of the nozzle of the solder jet 110 along the transport direction, the shape of the solder jet 110 is not disturbed while the thin plate 201 is in contact with the solder jet 110. As a result, it becomes possible for the infrared camera 107 to acquire a thermal image that accurately reflects the shape of the solder jet 110.

[0056] For example, if a space 219 is provided between W1 and WS so that W1>(WS / 2) is satisfied, it is possible to avoid disturbance of the shape of the solder jet 110 and acquire a thermal image of the thin plate 201. Note that the above WS can be set in accordance with the width of the solder jet 110 (e.g., the width of the secondary jet 112) generated when the motor 108 of the molten solder bath 102 in the soldering apparatus 100 is driven at maximum output.

[0057] 6A and 6B also show the mounting structure of the thin plate 201 to the upper jig 211, the lower jig 212, and the spacer 213 by the knurled screw 214 and the bolt 216, as described in FIG. 4A to FIG. 4C. That is, the thin plate 201 is fixed to both the upper jig 211 and the lower jig 212 without being in close contact with each other due to the presence of the spacer 213, and a gap 218 is provided between the thin plate 201 and the upper jig 211 in the plate thickness direction. Also, a gap 221 is provided between the knurled screw 214 and the hole in the thin plate 201 through which the knurled screw 214 passes due to the difference between their diameters. The gap 218 corresponds to an example of the "first gap", and the gap 221 corresponds to an example of the "third gap". In this way, thin plate 201 is fixed with gaps in both the thickness direction and the surface direction, so that thin plate 201 can come into contact with solder jet 110 while maintaining a flat surface without being deformed due to thermal expansion.

[0058] 4A to 4C, a configuration example of the conveying member 210 in which the lower jig 212 is in a square shape has been described, but the configuration of the conveying member 210 is not limited to this example.

[0059] 7 and 8 show modified configurations of the conveying member 210. FIG. 7, in the first modification, lower jig 212 of transport member 210 has a so-called "U" shape with an opening on the rear side in the transport direction, similar to upper jig 211. In this way, it is possible to transport evaluation device 200 while avoiding the disturbance of the shape of solder jet 110 without providing space 219 described in FIG. 6A. This also makes it possible to reduce the size of evaluation device 200. On the other hand, in the structure of FIG. 7, the structural strength of lower jig 212 is reduced compared to the "U" shape of FIGS. 4A to 4C.

[0060] 8, in the second modified example, the conveying member 210 configured in a U-shape like the first modified example further includes a reinforcing member 220 which is a separate member from the upper jig 211 and the lower jig 212. The lower jig 212 is fabricated to have a portion 212c longer than the upper jig 211 on the rear side in the conveying direction, i.e., on the opening side. Furthermore, the reinforcing member 220 is fixed by bolts 222 to the portions 212c on both sides facing each other in a direction intersecting the conveying direction.

[0061] In the structure of Fig. 8, the reinforcing material 220 is located above the thin plate 201 with respect to the outlet of the solder jet 110, so the shape of the solder jet 110 contacting the thin plate 201 is not disturbed by the reinforcing material 220. Therefore, it is possible to perform an evaluation test using the evaluation device 200 without providing the space 219 and avoiding the disturbance of the shape of the solder jet 110. Also, compared to Fig. 7, the structural strength of the transport member 210 can be ensured. In Fig. 8, the lower jig 212 corresponds to one embodiment of the "first member", and the reinforcing material 220 corresponds to one embodiment of the "second member".

[0062] Next, an evaluation test using the solder jet evaluation device according to the first embodiment will be described with reference to FIGS. 9A to 9C.

[0063] 9A shows a conceptual perspective view of evaluation device 200 passing above solder jet 110. In this state, solder jet 110 including primary jet 111 and secondary jet 112 partially contacts the lower surface of thin plate 201.

[0064] 9B conceptually shows the contact state of primary jet 111 and secondary jet 112 in the state of FIG. 9A with thin plate 201 by indicating evaluation device 200 with dotted lines. In thin plate 201, the temperature rises at the contact site with solder jet 110 (primary jet 111 and secondary jet 112), which is hatched in FIG. 9B.

[0065] Therefore, by photographing thin plate 201 in the state of FIG. 9A with infrared camera 107, a thermal image can be obtained that reflects the temperature rise in the blackened area of ​​FIG. 9B.

[0066] FIG. 9C shows a conceptual diagram illustrating the temperature distribution in the thermal image 250 using isothermal lines. 9C, in the thermal image 250, the portion of the thin plate 201 in contact with the solder jet 110 becomes hot. The isothermal line 111t shows a spotted temperature distribution corresponding to the contact portion with the primary jet 111. The isothermal line 112t shows a band-like temperature distribution corresponding to the contact portion with the secondary jet 112. That is, the isothermal lines 111t and 112t show the shapes of the primary jet 111 and the secondary jet 112 at the contact portion with the thin plate 201. That is, the states of the primary jet 111 and the secondary jet 112 can be evaluated based on the isothermal lines 111t and 112t.

[0067] For example, the thermal image 250 is divided into M×N pixel regions (M, N: natural numbers) so that the temperature on the surface of the thin plate 201 can be processed in association with coordinates. That is, the thermal image 250 is configured as a two-dimensional matrix having 640×480 pixel regions by dividing the horizontal direction (width direction) of the thermal image 250 into M (e.g., M=640) and the vertical direction (transport direction) into N (e.g., N=480).

[0068] As a result, the contact points with the solder jet 110, i.e., the primary jet 111 and the secondary jet 112, as shown in Fig. 9C can be identified from the temperature data in each of the multiple pixel regions in the thermal image 250. That is, the shape of the cut surface of the solder jet 110 by the evaluation device 200 (thin plate 201) can be detected by image processing of the thermal image 250. As a result, the state of the solder jet 110 (primary jet 111 and secondary jet 112) can be grasped, and it can be stably evaluated whether or not the state is such that a printed circuit board can be normally manufactured.

[0069] Embodiment 2 In the second embodiment, an example of determining whether a solder jet is good or bad in an actual soldering apparatus 100 will be described.

[0070] In the soldering apparatus 100 shown in FIG. 1, for example, in a molten solder bath 102 from which a solder jet 110 of lead-free solder (e.g., standard composition of Sn-3.0Ag-0.5Cu) is ejected, the temperature of the solder jet 110 is controlled to a target temperature (e.g., 250° C.) by a solder heating heater (not shown).

[0071] In this state, the evaluation device 200 for the solder jet described in the first embodiment is passed above the molten solder bath 102, and when the solder jet 110 and the evaluation device 200 (thin plate 201) are in contact with each other, an image of the evaluation device 200 (thin plate 201) is taken by the infrared camera 107. As a result, a thermal image 250 as shown in FIG. 9C is acquired.

[0072] FIG. 10 shows an example of image processing of a thermal image 250 . 10, as an example of image processing, a binarization process is performed with a threshold value of 240° C. for the temperature of solder jet 110 of 250° C. described above, and a processed image 252 is obtained in which areas at 240° C. or higher and areas below 240° C. are distinguished from each other. In FIG. 10, the areas at 240° C. or higher are indicated by hatching. Processed image 252 allows classification of each of the above-mentioned multiple pixel areas (e.g., 640×480 pixels) into areas at 240° C. or higher, i.e., areas in contact with solder jet 110, and areas below 240° C., i.e., areas not in contact with solder jet 110.

[0073] In the example image of Figure 10, the contact area with the primary jet 111 gradually shrinks toward the top in the figure because the transport conveyor 104 is inclined at a certain angle (e.g., about 5°) with respect to the horizontal plane, as shown in Figure 1.

[0074] In the processed image of FIG. 10, an inspection frame as shown in FIG. 11 is defined in advance. 11, an inspection frame 111c for primary jet 111 and an inspection frame 112c for secondary jet 112 can be provided in accordance with the jetting shape of solder jet 110 (primary jet 111 and secondary jet 112). Each of inspection frames 111c and 112c can be defined in units of a plurality of pixel regions (e.g., 640×480 pixels) as described in FIG. 9C.

[0075] As a result, in each of inspection frames 111c and 112c, contact areas (hatched areas) with solder jet 110 and non-contact areas (white areas) are distinguished in pixel area units. As a result, for example, in each inspection frame 111c, the quality of the state of primary jet 111 can be determined based on the area of ​​the contact area with solder jet 110 (the number of pixel areas) relative to the total area (the number of pixel areas). For example, when the ratio of the contact area to the total area is equal to or greater than a predetermined determination value (e.g., 40[%]), the state of primary jet 111 corresponding to that inspection frame 111c can be determined to be good (passed), whereas when the ratio is less than the determination value, the state of primary jet 111 can be determined to be poor (failed).

[0076] The state of the secondary jet 112 can be determined by introducing a quantitative value as explained in FIG.

[0077] Referring to FIG. 12, in the inspection frame 112c of the secondary jet 112, the contact length can be calculated by counting the number of pixels in the contact area (hatched area) at each of multiple points along the vertical direction of the screen (i.e., the line transport direction).

[0078] For example, in each inspection frame 112c, contact lengths L1 to L5 can be calculated at five points. Then, the average value of the contact lengths L1 to L5 can be set as the contact length of the secondary jet 112 in that inspection frame 112c. By determining whether the contact length (average value) is within a predetermined normal range (for example, 50[%] to 80[%] of the vertical length of the inspection frame 112c), it is possible to evaluate whether the condition of the secondary jet 112 is good (pass) or bad (fail).

[0079] In addition, by comparing the contact width between multiple inspection frames 112c provided for the secondary jet 112, it is also possible to evaluate the variation (fluctuation) in the jet state along the direction perpendicular to the line conveying direction of the secondary jet 112 (width direction).

[0080] 12, for example, the contact lengths (average values) LAV1 to LAV5 of the solder jets (secondary jets 112) are calculated for each of the five inspection frames 112c provided, and then the maximum value LAVmax of LAV1 to LAV5 is calculated relative to the average value LAV* (overall average value) of LAV1 to LAV5 to evaluate the variation in the width direction of the secondary jets 112. For example, if (LAV* / LAVmax) is equal to or greater than a predetermined judgment value (e.g., 80[%]), it can be judged that the variation in width of the solder jets 110 (secondary jets 112) is small and in a good condition.

[0081] As described in embodiment 2, the thermal image obtained by photographing with the evaluation device of embodiment 1 can be used to quantitatively determine the condition (good / bad) of the solder jets 110 (primary jet 111 and secondary jet 112) through image processing that distinguishes between contact and non-contact with the solder jet 110 for each pixel area.

[0082] FIG. 13 shows an example of a defective judgment based on a thermal image. 13, for the primary jet 111, the ratio of the contact area with the solder jet 110 in the inspection frames 111x, 111y, and 111z is lower than the judgment value, so that a defect is automatically detected. Also, from the position of the inspection frame 111c judged to be defective, the non-contact area or the area with insufficient contact of the primary jet 111 can be grasped. Similarly, for the secondary jet 112, the variation in the contact length with the solder jet 110 between the multiple inspection frames 112c is large, so that the secondary jet 112x having an uneven shape in the width direction can be grasped. As a result, an abnormality such as a blockage of the flow path of the solder jet 110, an inclination of the nozzle of the solder jet 110, or an insufficient flow rate of the solder jet 110 can be easily detected.

[0083] Thus, according to the second embodiment, the state of the solder jet 110 can be confirmed and evaluated using the solder jet evaluation device 200 before the start of the manufacturing process (mass production) of the printed circuit board 103 by the soldering device 100 or during the manufacturing process.

[0084] According to the second embodiment, when the state of solder jet 110 is judged to be defective by the above-mentioned quantitative evaluation, it is possible to estimate the cause of the defect from an actual thermal image.

[0085] In the second embodiment, inspection frames 111c and 112c are provided for the primary jet 111 and the secondary jet 112, respectively, and pass / fail judgment is performed based on the number of contact areas in each of the inspection frames 111c and 112c. However, pass / fail judgment is also possible without providing such inspection frames.

[0086] For example, a reference thermal image of the solder jet 110 when it is good can be defined in advance for the processed image 252 in FIG. 10. In the reference thermal image, whether each of a plurality of image regions (e.g., 640×480 regions) defined in common with the processed image 252 (FIG. 10) is a contact region or a non-contact region is set in advance. Therefore, a quantitative pass / fail judgment of the solder jet 110 similar to that described above can be realized by comparing a match rate (number of matching pixel regions / total number of pixel regions) by pattern matching, which judges whether each of a plurality of pixel regions is a contact region or a non-contact region, between the processed image 252 (FIG. 10) obtained from the thermal image 250 and the reference region, with a judgment value. The reference thermal image can be obtained in advance by an actual machine experiment in which a thermal image of the evaluation device 200 of the solder jet is taken in a soldering device 100 judged to be normal.

[0087] Furthermore, by outputting an abnormality detection signal in response to the occurrence of a defective state detected according to the second embodiment, it is possible to notify the manager and worker of the abnormality by an alarm and / or a screen display, etc. Through re-inspection and re-maintenance of the soldering apparatus 100 in response to the abnormality notification, the solder jet 110 can be returned to a normal state, and then the printed circuit board 103 can be soldered.

[0088] Moreover, the abnormality detection signal can be sent to a control unit (not shown) of the soldering device 100 to automatically stop the transport conveyor 104. This makes it possible to prevent soldering from continuing for a long period of time with the solder jet 110 in an abnormal state, thereby suppressing the rate of defective soldering of the printed circuit board 103.

[0089] Embodiment 3 In embodiment 3, a further description will be given of an evaluation method using the solder jet evaluation device according to embodiment 1. In embodiment 3, the method goes beyond automatic detection of defective states of solder jets using thermal images to automatically detect the causes of the defects.

[0090] First, a typical example of the cause of abnormal occurrence of the solder jet 110 will be described with reference to FIGS.

[0091] Fig. 14 shows a perspective view of soldering apparatus 100 which is the subject of anomaly detection in embodiment 3. The content of Fig. 14 is the same as Fig. 2, and the evaluation method for a solder jet according to embodiment 3 is executed by having infrared camera 107 acquire a thermal image when evaluation apparatus 200 described in embodiment 1 passes above molten solder bath 102 which is in a state of spraying solder jet 110.

[0092] Fig. 15 shows a cross-sectional view taken along line XV-XV in Fig. 14 when solder jet 110 is normal. Meanwhile, Figs. 16 to 18 show cross-sectional views at the same position as Fig. 15 for explaining typical causes of abnormality in solder jet 110.

[0093] 15 shows solder jet 110 in a normal state, with the dotted lines in the figure indicating the flow of solder. The solder inside molten solder bath 102 is heated by solder heater 121, and is sucked into a flow path by the rotation of impeller 124 driven by motor 108. The solder sucked by impeller 124 is ejected from nozzle 123 to form solder jet 110. Under normal conditions, in the width direction (i.e., within the XV-XV cross section), the surface of the solder at nozzle 123 and the conveying surface by transfer conveyor 104 are horizontal.

[0094] In contrast, typical causes of abnormalities in solder jet 110 include, for example, the following five.

[0095] (1) Occurrence of clogging in the flow path of the solder jet 110 (FIG. 16) (2) Inclination of solder nozzle 123 (Figure 17) (3) Inclination of the conveying surface caused by the conveyor 104 (FIG. 18) (4) Insufficient solder flow (5) Insufficient solder temperature 16, dross, which is an oxide of solder, or foreign matter 122 due to flux residue is generated, and clogging caused by the foreign matter 122 causes an abnormality in the solder jet 110 (Cause 1). In this case, it is necessary to take measures to remove the clogging caused by the foreign matter 122 by cleaning (Measure 1). 17, insufficient adjustment of the position of nozzle 123 of solder jet 110, or a tilt of nozzle 123 caused by a position adjustment error, causes an abnormality in solder jet 110 (Cause 2). In this case, it is necessary to measure the position of the nozzle of solder jet 110 with a vernier caliper or the like, and adjust the position of the nozzle of solder jet 110 by operating height adjustment bolt 125, thereby returning nozzle 123 to the horizontal (Countermeasure 2).

[0096] 18, if tilting of the transport surface occurs due to a difference in height or distortion between opposing transport conveyors 104, even if the ejected solder jet 110 is normal, there is a risk that the shape of the solder jet 110 will be abnormal when it comes into contact with the transport surface evaluation device 200 or the printed circuit board 103. For this reason, tilting of the transport surface caused by the transport conveyor 104 can also cause abnormalities in the solder jet 110 (Cause 3). In this case, adjustment is required to make the heights of the transport conveyors 104 uniform (Countermeasure 3).

[0097] Yet another cause is insufficient flow rate of solder due to insufficient output adjustment, output setting error, or damage of motor 108 that drives impeller 124 to move solder jet 110, which causes abnormality in solder jet 110 (Cause 4). In this case, adjustment of output of motor 108 or maintenance is required (Countermeasure 4).

[0098] Alternatively, insufficient temperature of the solder due to insufficient adjustment, incorrect settings, or damage to the temperature regulator (not shown) of the heater 121 for heating the solder may also cause an abnormality in the solder jet 110 (Cause 5). In this case, adjustment or maintenance of the temperature regulator of the heater 121 for heating is required (Countermeasure 5). As described above, there are multiple causes of defects in solder jet 110, and the measures to be taken vary depending on the cause. Therefore, when a defect is detected in the evaluation test of solder jet 110 based on the thermal image captured by evaluation device 200 (thin plate 201) as described in the second embodiment, it is preferable to estimate the cause of the abnormality and provide "adjustment guidance" that guides adjustment items as a countermeasure.

[0099] FIG. 19 is a flowchart illustrating a method for evaluating a solder jet and a method for manufacturing a printed circuit board according to the third embodiment.

[0100] 19, the manufacturing process of the printed circuit board according to this embodiment includes a solder jet evaluation step P100 and a soldering step P200. The solder jet evaluation step P100 includes steps S100 to S180 for performing the solder jet evaluation method according to this embodiment. The processing of steps S100 to S180 is performed by, for example, controller 300 (FIG. 3).

[0101] Referring to FIG. 19, in step S100, the controller 300 acquires thermal imaging data captured by the infrared camera 107 while the thin plate 201 of the evaluation device 200 described in the first embodiment is in contact with the solder jet 110 above the molten solder bath 102.

[0102] The controller 300 calculates an evaluation parameter value indicating a feature of the captured thermal image by S110. For example, the evaluation parameter value includes numerical data indicating an absolute value of temperature, density of isotherms, shape of isotherms, and change amount of isotherms with respect to a temperature distribution determined to be normal. Specifically, in an arbitrary region of the thermal image, the average temperature, maximum temperature, temperature gradient, a value obtained by dividing the area of ​​an isotherm of an arbitrary temperature by its perimeter, the number of isothermal regions with a temperature equal to or higher than an arbitrary temperature, a difference value between a temperature distribution in the captured thermal image and a temperature distribution determined to be normal in advance, and the like can be used as the evaluation parameter value. In addition, the above feature may be used as the evaluation parameter value by synthesizing multiple parameters or extracting independent parameters by software for executing a principal component analysis method, which is a known technique, and software for executing an independent component analysis method.

[0103] The controller 300 executes a process of determining the quality of the solder jet 110 based on the thermal image in S120. The process of determining the quality can be executed based on the area ratio of the contact region with the solder jet 110 within the inspection frames 111c, 112c shown in Figs. 11 to 13 of the second embodiment. Alternatively, as explained in the second embodiment, the quality determination in S120 can be executed by pattern matching between a predetermined reference thermal image and a processed image 252 (Fig. 10) of the thermal image.

[0104] The reference thermal image may be configured to define the actual temperature distribution in addition to defining the contact and non-contact areas with the solder jet 110 for each pixel region. In this case, the quality determination may be performed by pattern matching the temperature distribution of the reference thermal image with the temperature distribution of the thermal image 250 using any known method.

[0105] Furthermore, in S120, a defect cause determination process for adjustment guidance is executed using the evaluation parameter values ​​calculated in S110. The defect cause determination process is executed using past evaluation parameter values ​​accumulated in a database (DB) 360. As an example, the defect cause determination process can be executed by machine learning of the evaluation parameter values ​​accumulated when the state of the solder jet 110 was determined to be defective in the past.

[0106] For example, the cause of a defect can be determined by machine learning using a neural network as shown in FIG.

[0107] FIG. 20 is a conceptual diagram illustrating a neural network used in an example of machine learning for defect cause determination processing.

[0108] 20, neural network 370 includes n neurons Ni1 to Nin (n: an integer of 2 or more) constituting an input layer, m neurons No1 to Nom (m: a natural number of 2 or more) constituting an output layer, and a plurality of neurons constituting a hidden layer connected between the input layer and the output layer. The structure of neural network 370 can be set arbitrarily depending on the numbers of input layers, hidden layers, and output layers, and the number of neurons in each layer.

[0109] An activation function is input to each neuron represented by a circle symbol in Fig. 20. For example, a sigmoid function can be used as the activation function, but any known activation function can be applied. Furthermore, the weighting coefficients between each neuron can be determined by machine learning using multiple learning data obtained from past performance values, as described later.

[0110] The n neurons in the input layer are each input with a plurality (n) of evaluation data calculated in S110. Meanwhile, the m neurons in the output layer are each associated in advance with each of the causes of defects in solder jet 110 (for example, the above-mentioned (Cause 1) to (Cause 5)).

[0111] The training data for the neural network 370 can be obtained by an experiment in which a state in which the solder jet 110 is defective due to a specific cause is intentionally created in the soldering apparatus 100. That is, an evaluation test is performed in which the evaluation apparatus 200 takes a thermal image under the condition that such a specific cause of failure is generated, and the evaluation parameter values ​​obtained at this time are input to the neurons in the input layer. In the output layer, the value of the neuron corresponding to the specific cause of failure is set to "1", and the values ​​of the other neurons are set to "0". By providing such values ​​of the neurons in the input layer and the output layer, a set of training data can be constructed.

[0112] By performing similar experiments and evaluation tests for each different cause of failure, it is possible to obtain training data that covers a plurality of causes of failure. In addition, by substituting the evaluation parameters obtained in the evaluation test when the solder jet 110 is in a normal state into the input layer and setting each neuron value in the output layer to "0", it is possible to obtain training data in a normal state (when the solder jet 110 is in a good state).

[0113] In this way, the neural network 370 can be obtained by machine learning using teacher data under normal and abnormal conditions obtained in advance by actual experiments with the soldering apparatus 100. The structure of the neural network 370 and data indicating the weighting coefficients between the neurons can be stored in the database 360.

[0114] 19 again, in S120, the controller 300 inputs the evaluation parameter values ​​calculated in S110 to each of a plurality (n) of neurons constituting the input layer of the neural network 370 (FIG. 20). As a result, each of a plurality (m) of neurons constituting the output layer outputs a predicted probability of occurrence of the defect cause associated in advance as a value in the range of 0 to 1.0.

[0115] Therefore, when the condition of the solder jet 110 is judged to be defective in the above-mentioned pass / fail judgment, a defect cause judgment process can be executed to extract a defect cause that is presumed to be currently occurring from a plurality of predetermined causes based on the output values ​​of each neuron in the above-mentioned output layer. The controller 300 outputs the results of the pass / fail judgment process and the defect cause judgment process in S120 in S130.

[0116] When it is determined that the state of solder jet 110 is good (YES in S170), controller 300 ends solder jet evaluation process P100. At this time, controller 300 can output guidance using display unit 109 to the effect that the state of solder jet 110 is good and that mass production of printed circuit boards 103 may be started by soldering process P200 using soldering apparatus 100 as is.

[0117] Thus, in the soldering apparatus 100 in which the solder jet 110 is in a good condition, the printed circuit board 103 is passed in sequence over the molten solder bath 102 using the transport conveyor 104, thereby executing the printed circuit board soldering process P200.

[0118] On the other hand, when it is determined that the state of solder jet 110 is defective (NO determination in S170), controller 300 outputs adjustment guidance on display unit 109 in S180 and ends solder jet evaluation process P100. In S180, a defect cause with a high probability of occurrence is extracted by the defect cause determination process in S120, and guidance is output to notify measures for the extracted defect cause. For example, from a plurality of messages for notifying each of (Measures 1) to (Measures 5) that are predetermined corresponding to each of the above-mentioned (Causes 1) to (Causes 5), a message corresponding to the extracted defect cause can be selectively output as adjustment guidance.

[0119] Alternatively, in S180, if it is necessary to adjust the output of the drive system that drives the solder jet 110 or the solder temperature of the molten solder bath 102 in conjunction with the estimation result, it is also possible to automatically adjust the output of the motor 108 or the heater 121 for heating the solder.

[0120] After the adjustment guidance is output, the worker can adjust or maintain the soldering apparatus 100 according to the guidance, and then mass production can be started in the soldering process P200. Alternatively, it is possible to end the flow chart of Fig. 19 once without proceeding to the soldering process P200 in order to reevaluate the state of the solder jet 110 after the inspection or maintenance. In this case, the process according to the flow chart of Fig. 19 will be executed again.

[0121] The controller 300 can add the evaluation parameter values ​​calculated in S110 as teacher data for machine learning every time the solder jet evaluation process P100 is performed. That is, the machine learning can be performed continuously even during actual use of the soldering apparatus 100 (after going online). For example, the controller 300 evaluates and confirms the results of the pass / fail judgment and the defect cause judgment process outputted in S130 in S150 and S160, and converts them into teacher data. As described above, when the result is judged to be "good (YES in S170)", the evaluation parameter values ​​calculated in S120 are set as the values ​​of the neurons in the input layer, and the values ​​of each neuron in the output layer are set to 0, thereby creating teacher data.

[0122] On the other hand, if it is judged to be “defective (S170 is NO)”, training data can be created by determining the value of the neurons in the output layer to reflect the cause of the defect identified through adjustment or maintenance of the soldering apparatus 100 based on the adjustment guidance, etc.

[0123] The created teacher data is added and stored in database 360. By adding the additional teacher data and re-executing machine learning, it is possible to update neural network 370 used for the judgment in S120 using data obtained through actual use of soldering apparatus 100.

[0124] Alternatively, in S130, it is possible to output time-series regression prediction information for grasping the tendency of the condition of the solder jet 110 becoming abnormal, regardless of the pass / fail judgment result, i.e., even if the solder jet 110 is judged to be in a good condition.

[0125] FIG. 21 shows a conceptual diagram illustrating an example of regression prediction. 21, the evaluation parameter values ​​(i.e., temperature distribution feature quantities) calculated in S120 are stored in a database (DB) 360, and can be plotted as time-series data on the time axis. Therefore, for each evaluation parameter value, a regression line 380 of the time-series change can be found by known statistical processing.

[0126] 21, even when an upper limit and a lower limit are set for any of the evaluation parameter values ​​for management, the tendency for the evaluation parameter value to rise or fall before the parameter value reaches the upper limit or lower limit can be detected from the slope of regression line 380, etc. As a result, even when the condition of solder jet 110 is determined to be good, the tendency for the condition to gradually become abnormal can be grasped in advance. This allows equipment cleaning or maintenance to be carried out efficiently.

[0127] In this way, according to the third embodiment, the state of the solder jet can be stably determined using thermal images by performing a solder jet evaluation test using the solder jet evaluation device 200 described in the first embodiment. Furthermore, after confirming that the state of the solder jet 110 is good, a manufacturing process can be realized in which the printed circuit board 103 is continuously soldered, thereby suppressing the occurrence of defective products.

[0128] Furthermore, if the condition of the solder jet 110 is judged to be defective, the cause of the defect can be estimated by machine learning of the feature quantities (evaluation parameter values) of the heat distribution on the thermal images acquired in the solder jet evaluation test that have been accumulated up to that point. Furthermore, it is also possible to automatically output guidance for dealing with the estimated cause of the abnormality.

[0129] Furthermore, by performing an evaluation test of the solder jet 110 using the evaluation device 200 each time the soldering device 100 is used, a database is constructed that sequentially accumulates information related to the thermal images and the judgment results, and this information is reflected in machine learning, thereby improving the accuracy of estimating the cause of the abnormality.

[0130] Embodiment 4 In the first to third embodiments, the state of solder jet 110 is evaluated using a thermal image of the contact surface between solder jet 110 and thin plate 201 simulating the object to be soldered (printed circuit board 103). On the other hand, in evaluating the state of solder jet 110, it is also important to evaluate the shape of the vertical cross section of solder jet 110.

[0131] 22A to 22C show examples of the shape of secondary jet 112 of solder jet 110 in a vertical cross section along the transport direction of transport conveyor 104 (hereinafter also referred to as a first vertical cross section).

[0132] As shown in FIGS. 22A to 22C, the shape of the solder jet in the first vertical cross section changes depending on the angle of nozzle 126 that forms nozzle outlet 123 and the position of backplate 127 that is disposed at the terminal end of nozzle 126.

[0133] For example, by rotating nozzle 126 as shown in FIG. 22B or raising back plate 127 as shown in FIG. 22C, the shape of secondary jet 112 in the first vertical cross section (hereinafter also simply referred to as the "cross-sectional shape") can be changed downstream in the conveyor transport direction, relative to the state shown in FIG. 22A.

[0134] Next, the effect of the cross-sectional shape of the solder jet on soldering will be described. Fig. 23A shows the cross-sectional shape of the solder jet (secondary jet 112) when printed circuit board 103 has not passed. In contrast, Fig. 23B shows the contact state between the solder jet (secondary jet 112) having the cross-sectional shape shown in Fig. 23A and printed circuit board 103 when printed circuit board 103 has passed.

[0135] FIG. 23B shows the contact length L between the solder jet (secondary jet 112) and the printed circuit board 103 along the transport direction, as explained in the second embodiment (FIG. 12). Even if the contact length L is the same, if the contact angle between the two is different, it will affect the quality of the soldering. The contact angle can be evaluated using the departure angle θwd shown in FIG. 23B as a parameter.

[0136] The separation angle θwd is defined as the angle between the printed circuit board 103 and the contour surface (top surface) of the solder jet (secondary jet 112) at the end along the transport direction of the contact point between the printed circuit board 103 and the solder jet (secondary jet 112) in the first vertical cross section described above.

[0137] Fig. 24A shows the cross-sectional shape of the solder jet (secondary jet 112) when backplate 127 is raised with respect to Fig. 23A. Furthermore, Fig. 24B shows the contact state between the solder jet (secondary jet 112) having the cross-sectional shape shown in Fig. 24A and printed circuit board 103 when printed circuit board 103 passes.

[0138] As can be seen from a comparison of FIG. 23B and FIG. 24B, by changing the cross-sectional shape of the solder jet 110 by manipulating the back plate 127, the departure angle θwd of the printed circuit board 103 can be changed.

[0139] As a general trend, when the separation angle θwd is large, there is an advantage that the amount of solder attached to the printed circuit board 103 can be increased, but there is a possibility that a disadvantage is that short-circuit defects are likely to occur in components with narrow electrode spacing. On the other hand, when the separation angle θwd is small, the advantages and disadvantages are reversed from when the separation angle θwd is large.

[0140] Therefore, the separation angle θwd is optimized by adjusting the cross-sectional shape of the solder jet in accordance with the specifications of the printed circuit board 103 to be soldered. For example, when soldering a printed circuit board 103 that has many components to be inserted into the through-holes, the separation angle θwd is increased to ensure the amount of solder that adheres to the through-hole electrodes, thereby ensuring soldering quality. On the other hand, when soldering a printed circuit board 103 that has many components with narrow electrode spacing, such as QFPs (Quad Flat Packages) or connectors, the separation angle θwd is reduced to prevent short circuits between electrodes.

[0141] 23A and 24A, the cross-sectional shape of the solder jet can be controlled by adjusting the shape and angle of nozzle 126 or the rotation speed of motor 108. In the evaluation of the solder jet described in the first to third embodiments, thin plate 201 is used to monitor the change in shape of the solder jet within the contact surface between printed circuit board 103 and the solder jet, for example, by using the contact length, but it is difficult to evaluate the cross-sectional shape of the solder jet, which affects the above-mentioned separation angle θwd, etc.

[0142] In the fourth embodiment, a method for evaluating a solder jet based on the shape of a vertical cross section of the solder jet will be described.

[0143] 2 again, in the fourth embodiment, in the evaluation device 200, the thermal image of the solder jet itself in the horizontal plane is taken by directly photographing the solder jet 110 using the infrared camera 107 without the evaluation device 200 (thin plate 201) being present. Hereinafter, the thermal image of the solder jet 110 will be given the reference symbol 400 to distinguish it from the thermal image 250 of the thin plate 201 described in the first to third embodiments. Note that the thermal image 250 and the thermal image 400 may be taken by a common infrared camera 107, or may be taken by infrared cameras 107 arranged separately.

[0144] 25A and 25B show examples of the thermal image and cross-sectional shape (first vertical cross section along the conveying direction) of a solder jet. Fig. 25A shows an example of a thermal image 400 in which the cross-sectional shape of the solder jet has a large change in slope, while Fig. 25B shows an example of a thermal image 400 in which the cross-sectional shape of the solder jet has a small change in slope.

[0145] In the following drawings of the present application, the thermal images 400 are shown as color images displayed in grayscale. Therefore, although each thermal image 400 shows shading corresponding to the temperature difference between adjacent regions, points of the same brightness in the same image do not necessarily mean that they have the same temperature.

[0146] In addition, since the solder jet ejected from the nozzle 123 has a mirror-like surface and a low emissivity, the measured temperature of the solder jet by the infrared camera 107 is lower than the actual temperature of the solder jet. Furthermore, the infrared camera 107 measures the temperature of the liquid surface of the solder that has flowed out of the nozzle 126 and is in a stagnant state higher than the temperature of the liquid surface of the portion in a flowing state including the primary jet 111 and the secondary jet 112, but in reality, the two temperatures are the same. On the liquid surface of the solder in a stagnant state, a relatively thick oxide film is formed, or solder oxide (dross) floats, which makes the emissivity from the liquid surface relatively high, so the temperature difference as described above occurs in the measured temperature by the infrared camera 170. By utilizing this feature, it becomes easy to separate the portion of the solder jet 110 including the primary jet 111 and the secondary jet 112 from the stagnant state that has flowed out of the nozzle 126, and therefore it becomes easy to grasp the state of the solder jet 110.

[0147] 25A and 25B, the positions and planar shapes of the primary jet 111 and the secondary jet 112 can be visually confirmed from the temperature distribution in the thermal image 400. Furthermore, regarding the temperature distribution in the region of the secondary jet 112, a band-shaped region 401 that is lower in temperature than the surroundings (regions before and after along the conveying direction) is observed in the center in FIG. 25A. On the other hand, in FIG. 25B, there is no low-temperature region like the band-shaped region 401 in FIG. 25A in the center 401x.

[0148] Additionally, FIGS. 25A and 25B show schematic cross-sectional views of secondary jets 112 of solder jets 110 corresponding to respective thermal images 400. FIG.

[0149] As shown in Fig. 25A, the low-temperature band-like region 401 occurs in a region where the inclination change of the cross-sectional shape of the solder jet (secondary jet 112) is large. In particular, in the thermal image 400 in Fig. 25A, the low-temperature band-like region 401 is located near the end (downstream end in the conveying direction) of the jet outlet 123, which corresponds to the region where the printed circuit board 103 leaves the solder jet 110 as shown in Fig. 23B and Fig. 24B. If the cross-sectional shape of the solder jet 110 changes significantly in such a region, there is a concern that the above-mentioned departure angle θwd will change from the appropriate value, thereby degrading the soldering quality.

[0150] On the other hand, as shown in FIG. 25B, when the change in inclination of the cross-sectional shape of the solder jet (secondary jet 112) is small, it is understood that the low-temperature area (band-shaped region 401) as shown in FIG. 25A does not appear in the thermal image 400.

[0151] Fig. 26 shows a conceptual cross-sectional view explaining the relationship between the cross-sectional shape of the solder jet and the radiant energy to the infrared camera. The vertical axis of Fig. 26 indicates the vertical position (z), and the horizontal axis of Fig. 26 corresponds to the x-axis, with the conveying direction being positive. As described above, the conveying direction is inclined at a certain angle (for example, about 5°) with respect to the x-axis along the horizontal plane, but in the thermal image 400 of the horizontal plane, the x-axis direction and the conveying direction are synonymous.

[0152] 26, in a vertical cross section of the solder jet (secondary jet 112), infrared radiation energy of the solder jet is emitted from each point on the periphery of the cross-sectional shape in the normal direction of the shape. In contrast, the infrared radiation energy from each measurement point 115 on the periphery captured by infrared camera 107 depends on the direction cosine (cos θv) of the angle θv between the normal direction and a straight line (shown by a dotted line in the figure) connecting measurement point 115 and infrared camera 107.

[0153] Therefore, it can be understood that even among measurement points 115 with the same temperature, the detected temperature of the infrared camera 107 corresponding to the measurement point 115 with a large direction cosine cosθv will be higher, and the detected temperature of the infrared camera 107 corresponding to the measurement point 115 with a small direction cosine cosθ will be lower.

[0154] 26 shows a graph of cos θv corresponding to the cross-sectional shape of the solder jet (secondary jet 112). From this graph, it can be seen that cos θv changes in response to the change in the cross-sectional shape of the solder jet (secondary jet 112).

[0155] As a result, as shown in Figure 27, an analogy is established between the distribution shape of cosθv at each measurement point on the outer periphery of the cross-sectional shape of the solder jet 110 and the temperature profile showing the distribution of the detected temperature Tdet by the infrared camera 107 at the measurement point.

[0156] 26 and 27, in the cross-sectional area corresponding to band-shaped region 401 in Fig. 25A, the change in inclination of the cross-sectional shape of the solder jet is large, and so cos θv is lower than in adjacent regions. As a result, in the region where the cross-sectional shape of the solder jet (secondary jet 112) changes and the inclination angle changes, band-shaped region 401 is observed to be cooler than its neighbors in the x-axis direction due to the lower cos θv.

[0157] Therefore, it can be understood that it is possible to monitor whether or not a disturbance in the cross-sectional shape of the solder jet that affects the separation angle θwd (specifically, a large change in inclination) has occurred by checking the temperature distribution (temperature profile) on a straight line (x-axis) along the transport direction in a horizontal plane in the thermal image 400, as well as the width and position of the low-temperature area such as the band-shaped area 401. For example, the above-mentioned monitoring can be performed by visually checking the thermal image 400 displayed as a color image on the display unit 109.

[0158] Alternatively, it is possible to quantitatively perform the above-mentioned monitoring by calculating an evaluation parameter value for evaluating the cross-sectional shape of the solder jet in a first vertical cross section along the transport direction from the temperature distribution (temperature profile) of the detected temperature Tdet acquired by the thermal image 400, and comparing the evaluation parameter value with a predetermined judgment value.

[0159] In this way, it is possible to judge whether the cross-sectional shape of the solder jet is good or bad from the temperature distribution along the x-axis direction (transport direction) of the temperature Tdet detected by the infrared camera 107 in the horizontal plane of the thermal image 400, particularly in the area corresponding to the secondary jet 112. For example, it is possible to adjust the angle of the nozzle 126 or the rotation speed of the motor 108 based on the judgment result, thereby adjusting the separation angle θwd.

[0160] Furthermore, changes in the flow rate of the solder jet can also be monitored based on the same temperature distribution.

[0161] 28 shows the change in the cross-sectional shape of the solder jet with respect to the change in the flow rate of the solder jet. Compared to cross-sectional profile 461 at the time of the appropriate flow rate, cross-sectional profile 460 at the time of a large flow rate and cross-sectional profile 462 at the time of a small flow rate have different outer peripheral shapes.

[0162] As a result, as shown in the upper part of FIG. 28, with respect to the temperature distribution along the conveying direction of the detected temperature Tdet of the infrared camera 107, the temperature profile 450 when the flow rate is large expands in the x-axis direction, and the valley of the temperature distribution moves in the positive x-axis direction, compared to the temperature profile 451 when the flow rate is appropriate. On the other hand, the temperature profile 452 when the flow rate is small contracts in the x-axis direction, and the valley of the temperature distribution moves in the negative x-axis direction, compared to the temperature profile 451 when the flow rate is appropriate. Therefore, by monitoring the temperature profile along the x-axis direction of the solder jet 110, it is possible to monitor the flow rate of the solder jet 110. For example, a reference flow rate thermal image at the appropriate flow rate when the temperature of the solder jet 110 is controlled to a predetermined temperature is determined in advance, and a change in the flow rate of the solder jet 110 can be easily detected based on a comparison between the reference flow rate thermal image and the current thermal image 400 by visually observing the thermal image 400 or by monitoring based on the above-mentioned evaluation parameter values. By adjusting the rotation speed of the motor 108 etc. in response to the detection of such a change in the flow rate, it becomes possible to maintain and manage the same solder jet state.

[0163] Thermal image 400 can also be used to monitor primary jet 111 of solder jet 110.

[0164] 29A and 29B show a thermal image 400 of a primary jet 111 of a solder jet 110, and a graph showing the distribution of detected temperatures Tdet in the width direction within a surface of the thermal image 400.

[0165] FIG. 29A shows an example of temperature distribution under normal circumstances when no nozzles are clogged, while FIG. 29B shows an example of temperature distribution under abnormal circumstances when some nozzles are clogged.

[0166] FIG. 29A further shows a graph indicating the distribution of the detected temperature Tdet with respect to the position on the line AA in the thermal image 400. Similarly, FIG. 29B shows a graph indicating the distribution of the detected temperature Tdet with respect to the position on the line BB in the thermal image 400. The lines AA and BB are lines along a direction perpendicular to the conveying direction (hereinafter also referred to as the "width direction") in a horizontal plane. The graphs in FIG. 29A and FIG. 29B are written with the horizontal and vertical axes rotated by 90 degrees, and the horizontal axis indicates the position (y coordinate) on the line AA or the line BB. These graphs show the temperature profile of the solder jet (primary jet) 111 along the width direction.

[0167] 29B, there are low-temperature regions 470, 471 in the thermal image 400 that correspond to the clogged nozzle locations, and in the temperature profile in the width direction, there is a region of reduced detected temperature Tdet that corresponds to the low-temperature region 470 located on line BB. In the area where the clogged nozzle occurs, the shape of the solder jet (primary jet 111) becomes distorted and the infrared radiation energy decreases, so that the detected temperature Tdet of that area by the infrared camera 107 decreases.

[0168] In contrast, in Fig. 29A, there are no localized low temperature areas like low temperature areas 470, 471 in Fig. 29B, and in the temperature distribution (profile) on line AA, there are no areas of temperature drop corresponding to nozzle clogging like line BB in Fig. 29B.

[0169] In this way, the primary jet 111 can also be monitored for the presence or absence of nozzle clogging based on the temperature profile in the width direction in the thermal image 400. The determination of the presence or absence of nozzle clogging is equivalent to evaluation of the shape of a vertical cross section (hereinafter also referred to as a second vertical cross section) of the primary jet 111 (solder jet 110) along the width direction (the direction of the straight lines AA and BB in Figs. 29A and 29B). This monitoring can also be performed by visually observing the thermal image 400 or based on evaluation parameter values ​​that reflect the temperature distribution appearing in the thermal image 400. In this way, the vertical cross-sectional shape of the solder jet 110, more specifically, the shape of the secondary jet 112 in the first vertical cross section along the transport direction and the shape of the primary jet 111 in the second vertical cross section along the width direction can be evaluated based on the temperature distribution within the surface of the thermal image 400.

[0170] The evaluation parameter values ​​for quantitatively evaluating the temperature distribution appearing in such a thermal image 400 (thermal image of the solder jet 110) can also be efficiently calculated based on the temperature detection values ​​in the inspection frames provided corresponding to the primary jet 111 and the secondary jet 112, as in the thermal image 250 (thermal image of the thin plate 201) described in embodiment 2.

[0171] FIG. 30A shows a conceptual diagram illustrating an example of setting an inspection frame for monitoring the primary jet 111.

[0172] 30A, a plurality of inspection frames 510 can be provided in the thermal image 400 in correspondence with the jetting shape of the primary jet 111. That is, the positions of the plurality of inspection frames 510 can be determined in advance in correspondence with the arrangement area of ​​the nozzle that jets the primary jet 111.

[0173] For example, in each inspection frame 510, the average value of the detected temperatures Tdet at multiple pixels included in that inspection frame 510 can be calculated as the evaluation parameter value. Then, in an inspection frame 510 in which the evaluation parameter value (average temperature) is lower than a predetermined judgment temperature, it can be determined that the corresponding nozzle is clogged. Alternatively, it is also possible to further calculate the average value (overall average value) of the evaluation parameter values ​​of each of the multiple inspection frames 510, compare it with the overall average value, and detect a clogged nozzle in an inspection frame 510 in which the evaluation parameter value is lower by more than a certain value.

[0174] FIG. 30B shows a conceptual diagram illustrating an example of setting an inspection frame for monitoring the secondary jet 112.

[0175] As shown in FIG. 30B, the secondary jet 112 inspection frame 511 The position of the inspection frame can be set to correspond to the part where the printed circuit board 103 separates from the solder jet 110 in order to evaluate the separation angle θwd. 511 The average value of the detected temperatures Tdet at the multiple pixels included in the area can be calculated as the evaluation parameter value.

[0176] For example, when the evaluation parameter value is lower than a judgment temperature determined based on the temperature of the solder jet 110, it can be determined that a change in the cross-sectional shape (vertical cross section along the transport direction) of the solder jet (secondary jet 112) that affects the separation angle θwd (Figure 25A) has occurred.

[0177] Alternatively, instead of comparing with the judgment value, it is also possible to further set a comparison inspection frame (not shown) adjacent to inspection frame 511 in the transport direction, and further calculate the evaluation parameter values ​​(average temperature) of the comparison inspection frame and inspection frame 511, and when a difference in average temperature occurs between inspection frame 511 and the comparison inspection frame that is equal to or greater than a certain value, it is possible to determine that a change in the cross-sectional shape of the solder jet (secondary jet 112) described above has occurred.

[0178] Alternatively, similar to the thermal image 250 (thermal image of thin plate 201) described in embodiment 2, it is also possible to determine whether the condition of solder jet 110 is good or bad by comparing a predetermined normal thermal image of thermal image 400 (solder jet 110) with the actual thermal image taken by infrared camera 107 by pattern matching.

[0179] Considering that the solder jet 110 is a fluid, in order to reduce fluctuations in the measurement data (temperature detection values) due to fluctuations in the liquid surface, it is also possible to obtain a thermal image for evaluating the solder jet, i.e., temperature distribution data, from the measurement data (temperature detection values) obtained by averaging thermal images 400 taken at different times.

[0180] FIG. 31 is a flowchart illustrating a method for evaluating a solder jet and a method for manufacturing a printed circuit board according to the fourth embodiment.

[0181] 31, the manufacturing process of the printed circuit board according to the fourth embodiment includes a solder jet evaluation step P101 and a soldering step P200. The solder jet evaluation step P101 includes steps S101 and S111 relating to a thermal image 250 of the evaluation device (thin plate 201) in contact with the solder jet 110, steps S201 and S211 relating to a thermal image 400 of the solder jet 110, step S121, and steps S130 to S180 similar to those in FIG. 19. The processing of each step included in the solder jet evaluation step P101 is executed by, for example, the controller 300 (FIG. 3).

[0182] S101 and S111 are realized by the same process as S100 and S110 in Fig. 19. That is, in S101, the controller 300 photographs the thin plate 201 of the evaluation device 200 described in the first embodiment with the infrared camera 107 in a state where the thin plate 201 is in contact with the solder jet 110 above the molten solder bath 102, thereby acquiring thermal imaging data (thermal image 250) showing the temperature distribution in the surface of the thin plate 201. As a result, the controller 300 acquires the temperature detection value in the thermal image 250 by the infrared camera 107 as the thermal imaging data. Furthermore, in step S102, a predetermined evaluation parameter value (corresponding to the "first evaluation parameter value") showing the feature amount of the photographed thermal image 250 is calculated. As described above, various values ​​for quantitatively expressing the temperature distribution can be used as the evaluation parameter value.

[0183] In S201, the controller 300 captures thermal imaging data (thermal image 400) showing the temperature distribution in the horizontal plane of the solder jet 110 by capturing an image of the molten solder bath 102 with the infrared camera 107 without passing through the transported object on the transport conveyor 104. As a result, the controller 300 captures the temperature detection value of each pixel of the thermal image 400 by the infrared camera 107 as thermal imaging data. Furthermore, in S202, a predetermined evaluation parameter value (corresponding to the "second evaluation parameter value") showing the feature amount of the captured thermal image 400 is calculated. As described above, the evaluation parameter value can be various values ​​for quantitatively expressing the temperature distribution in addition to the examples in the fourth embodiment.

[0184] The controller 300 can execute S101 and S111 in response to the infrared camera 107 capturing the thermal image 250 at the timing when the evaluation device 200 (thin plate 201) is transported by the transport conveyor 104 and passes over the solder jet.

[0185] Furthermore, the controller 300 can execute the processes of S201 and S211 in response to the infrared camera 107 capturing the thermal image 400 before or after the capture timing of the thermal image 250. In this way, the processes of S101 and S111 and the processes of S201 and S211 can be executed in any order. Alternatively, depending on the capabilities of the controller 300, the processes of S111 and S211 can be executed in parallel.

[0186] In S121, the controller 300 executes a process for determining whether the state of the solder jet 110 is good or bad, based on both the thermal image 250 and the thermal image 400. The process for determining whether the state of the solder jet 110 is good or bad, based on the thermal image 250, can be executed in the same manner as described in Fig. 19. Furthermore, the process for determining whether the state of the solder jet 110 is good or bad, based on the thermal image 250, can also be executed by comparing an evaluation parameter value that quantitatively indicates the temperature distribution with a determination value, or by pattern matching with a reference image.

[0187] As a result, in S121, it becomes possible to further evaluate the vertical cross-sectional shape of solder jet 110 as explained in embodiment 4, and to judge the quality of the state of solder jet 110. As a result, it becomes possible to judge the quality of the state of solder jet 110 while taking into consideration the departure angle θwd, which is difficult to judge from the thermal image 250 of thin plate 201.

[0188] 19 using the evaluation parameter values, controller 300 can execute the process in S121 by further incorporating the cause of defect in the vertical cross-sectional shape of solder jet 110. For example, the machine learning model described in Fig. 20 can be configured to further incorporate the evaluation parameter values ​​(input layer) and the cause of defect (output layer) related to the vertical cross-sectional shape of solder jet 110.

[0189] In S130, controller 300 outputs the results of the pass / fail judgment process and the defect cause judgment process in S121, including the judgment result related to the vertical cross-sectional shape of solder jet 110 based on thermal image 400. As a result, in Fig. 31, the pass / fail judgment of the solder jet is performed, including the vertical cross-sectional shape of solder jet 110. In addition, in S130, regression prediction shown in Fig. 21 is also performed on the evaluation parameter values ​​based on thermal image 400, and it is possible to further output time-series regression prediction information related to the vertical cross-sectional shape of solder jet 110.

[0190] The processing of S170, S180 for the pass / fail determination result of solder jet 110 and soldering process P200 are similar to those in Fig. 19, and therefore detailed description will not be repeated. In addition to the description in Fig. 19, in S180, it is also possible to output adjustment guidance related to the vertical cross-sectional shape of solder jet 110 and to automatically adjust equipment (motor 108, nozzle 126, etc.).

[0191] Furthermore, in the processes of S150 and S160, the controller 300 can also convert the evaluation parameter values ​​calculated from the thermal image 400 into training data and store it in the database 360 ​​for machine learning.

[0192] In this way, according to the solder jet evaluation method of the fourth embodiment, in addition to the evaluation test of the solder jet using the evaluation device 200 described in the first to third embodiments, the vertical cross-sectional shape of the solder jet 110 (the first vertical cross section along the conveying direction and the second vertical cross section along the width direction) is also evaluated, so that the evaluation test of the solder jet can be performed with higher accuracy. This makes it possible to suppress the deterioration of the soldering quality caused by the defective separation angle θwd during soldering, in addition to the effects of the first to third embodiments. Furthermore, by realizing a manufacturing process in which the printed circuit board 103 is continuously soldered after confirming that the state of the solder jet 110 is good by the solder jet evaluation method of the fourth embodiment, the occurrence of defective products can be further suppressed.

[0193] FIG. 32 is a flowchart illustrating a method for evaluating a solder jet according to a modification of the fourth embodiment.

[0194] As shown in Fig. 32, the method for evaluating a solder jet according to the modification of the fourth embodiment includes a solder jet evaluation step P102 and a soldering step P200. In the solder jet evaluation step P102, steps S101 and S111 are omitted from the solder jet evaluation step P101 in Fig. 31. As a result, in the solder jet evaluation step P102, a quality determination process (S122) for the state of the solder jet 110 is performed based only on the thermal image 400 of the solder jet 110. Therefore, based on the evaluation result of the vertical cross-sectional shape of the solder jet 110, adjustment guidance is output (S180), etc., so that the soldering step (P200) can be prevented from being performed using a solder jet having an inappropriate cross-sectional shape.

[0195] 32 can be performed in a short time without transporting the evaluation device 200 (thin plate 201). Therefore, the solder jet evaluation process P102 can be performed multiple times without requiring a long time, for example, after the start of the soldering process P200. This increases the frequency of checking the vertical cross-sectional shape of the solder jet 110, thereby enabling early detection of abnormalities in the solder jet 110 and further improving the quality of the soldering process.

[0196] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0197] 100 soldering device, 101 housing, 102 molten solder bath, 103 printed circuit board, 104 conveyor, 105 preheater, 106 preheater, 107 infrared camera, 108 motor, 109 display unit, 110 solder jet, 111 primary jet, 111c, 111x, 111y, 111z, 112c, 510, 511, 512 inspection frame, 111t, 112c isotherm, 112, 112x secondary jet, 121 heater, 122 foreign matter, 123 nozzle, 124 impeller, 125 adjustment bolt, 200 evaluation device, 201 thin plate, 210 conveying member, 211 upper jig, 212 lower jig, 213 spacer, 214 knurled screw, 215 locating pin, 216,222 bolt, 217,218,221 gap, 219 space, 220 reinforcement, 250 thermal image (thin plate), 252 machining image, 300 controller, 320 memory, 350 bus, 360 database, 370 neural network, 380 regression line, 400 thermal image (solder jet), 401 strip area, 401x center, 450,451,452 temperature profile, 460,461,462 cross-sectional profile, 470,471 low temperature area.

Claims

1. A solder jet evaluation device for use in a soldering apparatus including a molten solder bath from which a solder jet is jetted, a transport conveyor for transporting an object to be soldered so as to pass above the molten solder bath, and a temperature distribution measuring device within a field of view directed from above the molten solder bath toward the transport conveyor and the molten solder bath, comprising: A conveying member conveyed on the conveyor; a thin plate member attached to the conveying member at a position above the molten solder bath where the thin plate member comes into contact with the solder jet, The thin plate member is made of a material and has a plate thickness of 0.1 or less.

2. the thin plate member is attached to the conveying member such that a first gap is provided between the thin plate member and the conveying member along a plate thickness direction of the thin plate member, 2. The solder jet evaluation device according to claim 1, wherein the first gap is larger than an amount of thermal expansion in the thickness direction that occurs in the thin plate member when the thin plate member comes into contact with the solder jet.

3. the thin plate member is attached to the conveying member such that a second gap is provided between the thin plate member and the conveying member along a surface direction of the thin plate member, 3. The solder jet evaluation device according to claim 1, wherein the second gap is larger than an amount of thermal expansion in the planar direction that occurs in the thin plate member when the thin plate member comes into contact with the solder jet.

4. the thin plate member is attached to the conveying member by a fixing member passing through a hole provided in the thin plate member, A solder jet evaluation device as described in any one of claims 1 to 3, wherein a third gap in the surface direction of the thin plate member caused by the difference between the diameter of the hole and the diameter of the fixing member is larger than the amount of thermal expansion in the surface direction that occurs in the fixing member when it comes into contact with the solder jet.

5. The transport member is configured to have a first side and a second side extending in a direction intersecting a transport direction of the transport conveyor, the first side is transported on the transport conveyor in the transport direction ahead of the second side, the thin plate member is attached to the conveying member such that a space is provided between the thin plate member and the second side, 5. The solder jet evaluation device according to claim 1, wherein the length of the space along the transport direction is longer than (1 / 2) the length of the solder jet along the transport direction.

6. The solder jet evaluation device according to any one of claims 1 to 4, wherein the transport member is configured in a shape that opens on its rear side along the transport direction of the transport conveyor when the thin plate member is attached.

7. The conveying member is a first member to which the thin plate member is attached; and a second member fixed to the first member, the first member has a shape that opens at a rear side along a conveying direction of the conveyor when the thin plate member is attached, The solder jet evaluation device according to any one of claims 1 to 4, wherein the second member is attached to the first member so as to be positioned above the thin plate member in correspondence with an opening portion of the first member.

8. The solder jet evaluation device according to any one of claims 1 to 7, the soldering device to be evaluated by the evaluation device; and a controller that determines whether the state of the solder jet is good or bad based on the temperature distribution within the surface of the thin plate member obtained by image processing of a thermal image obtained by measuring the thin plate member in contact with the solder jet using the temperature distribution measuring device when the evaluation device passes above the molten solder bath.

Images