CN114430717B

CN114430717B - Solder paste printing system and solder paste printing method

Info

Publication number: CN114430717B
Application number: CN202080066586.5A
Authority: CN
Inventors: 河内满; 芳贺浩贵; 德永政昭; 大石光浩; 田中哲矢
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2019-10-08
Filing date: 2020-09-09
Publication date: 2023-10-24
Anticipated expiration: 2040-09-09
Also published as: CN114430717A; DE112020004841T5; JPWO2021070541A1; WO2021070541A1

Abstract

The invention provides a solder paste printing system and a solder paste printing method. The solder paste printing system includes a printer, a detection unit, and a solder state determination unit. The printer prints a solder paste containing solder particles and flux on a substrate. The detection unit detects solder particles and flux of the solder paste printed on the substrate. The flux state determination unit determines whether the state of the flux is good or bad based on the detection result of the detection unit. If the solder state determination unit determines that the state of the solder paste is poor, the printer performs an operation of changing the state of the solder paste before printing the unprinted substrate.

Description

Solder paste printing system and solder paste printing method

Technical Field

The present disclosure relates to a solder paste printing system and a solder paste printing method that print a solder paste on a substrate.

Background

In the printer, the lower surface of the screen mask provided with the opening portion is in contact with the substrate. Then, the squeegee is moved over the screen mask, and the solder paste containing the solder particles and the flux is pressed into the opening portion so that the solder paste is transferred to the substrate. The substrate printed with the solder paste is photographed by a camera. Based on the imaging result, the presence or absence of defective printing is detected. The printing failure includes a state (solder bridge) in which the transferred solder paste is connected to an adjacent solder paste, and a state in which the solder paste is detached from a necessary position (for example, refer to patent document 1).

In the inspection method described in patent document 1, a solder paste (cream solder) colored to increase contrast with the substrate is used, and a camera photographs the substrate on which such solder paste is printed. Then, the presence or absence of printing failure was checked based on the shape of the photographed solder paste. If a defective printing is detected, the screen mask is cleaned.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 5-123892

Disclosure of Invention

The solder paste printing system of the present disclosure has a printer, a detection section, and a solder state determination section. The printer prints a solder paste containing solder particles and flux on a substrate. The detection unit detects solder particles and flux of the solder paste printed on the substrate. The flux state determination unit determines whether the state of the flux is good or bad based on the detection result of the detection unit. If the solder state determination unit determines that the state of the solder paste is poor, the printer performs an operation of changing the state of the solder paste before printing the solder paste on the unprinted substrate.

In the solder paste printing method of the present disclosure, a solder paste including solder particles and flux is printed on a substrate. Then, the solder particles and flux of the solder paste printed on the substrate were inspected and the inspection result was obtained. Based on the detection result, whether the state of the flux is good or bad is determined. If it is determined that the state of the flux is poor, an operation of changing the state of the flux of the solder paste is performed before printing the unprinted substrate.

According to the present disclosure, printing failure can be prevented.

Drawings

Fig. 1 is a schematic configuration diagram of a screen printing system according to an embodiment of the disclosure.

Fig. 2 is a block diagram of a printer in the screen printing system shown in fig. 1.

Fig. 3A is a cross-sectional view showing a process of printing solder paste by the printer shown in fig. 2.

Fig. 3B is a cross-sectional view showing a process of printing the solder paste subsequent to fig. 3A.

Fig. 3C is a cross-sectional view showing a process of printing the solder paste subsequent to fig. 3B.

Fig. 4 is a block diagram of a print solder inspection apparatus in the screen printing system shown in fig. 1.

Fig. 5A is a view showing an example of an image captured by an inspection camera when a substrate on which solder paste is printed is irradiated by the 1 st irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 5B is a view showing an example of an image captured by an inspection camera when the substrate shown in fig. 5A is irradiated with light by the 2 nd irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 6 is a functional block diagram showing the structure of a control system of the printer shown in fig. 2.

Fig. 7 is a functional block diagram showing the configuration of a control system of the printed solder inspection device shown in fig. 4.

Fig. 8A is a cross-sectional view showing an example of a state of the screen mask before printing in the printer shown in fig. 2.

Fig. 8B is a cross-sectional view showing an example of a state of the screen mask after printing in the printer shown in fig. 2.

Fig. 8C is a cross-sectional view showing an example of a state of the screen mask after printing is performed more times than the state shown in fig. 8B.

Fig. 8D is a cross-sectional view showing an example of a state of the screen mask after printing is performed more times than the state shown in fig. 8C.

Fig. 9A is a diagram showing an example of an image captured by an inspection camera by irradiating a substrate on which solder paste is printed using a screen mask in the state shown in fig. 8C by the 1 st irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 9B is a view showing an example of an image captured by an inspection camera when the substrate shown in fig. 9A is irradiated with light by the 2 nd irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 10A is a view showing an example of an image captured by an inspection camera by irradiating a substrate on which solder paste is printed using the screen mask in the state shown in fig. 8D by the 1 st irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 10B is a view showing an example of an image captured by an inspection camera while the substrate shown in fig. 10A is irradiated with light by the 2 nd irradiation section of the printed solder inspection apparatus shown in fig. 4.

Fig. 11 is a diagram showing an example of a detection result of the flux stored in the 2 nd storage unit of the printed solder inspection apparatus shown in fig. 7.

Fig. 12 is a flowchart showing a part of a screen printing method of the embodiment of the disclosure.

Fig. 13 is a flowchart showing another part of the screen printing method of the embodiment of the disclosure.

Detailed Description

Prior to describing embodiments of the present disclosure, a pass through to arrive at the concepts of the present disclosure will be briefly described. In patent document 1, a printing failure such as a solder bridge is detected based on the shape of the entire colored solder paste. Thus, it is impossible to distinguish between the solder particle connection and the flux connection contained in the solder paste. However, fluidity is different in solder particles and flux. Thus, the behavior of the solder bridge and the like before the occurrence of the printing failure is also different. Therefore, there is room for further improvement in order to capture a sign of printing failure during the screen printing repeatedly performed and to perform appropriate improvement processing before occurrence of printing failure.

The present disclosure provides a solder paste printing system and a solder paste printing method capable of preventing printing failure.

Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. The configuration, shape, and the like described below are examples for illustration, and can be changed as appropriate according to specifications of a screen printing system, a printer, a printing solder inspection apparatus, and a management computer. In the following, in all the drawings, the same reference numerals are given to corresponding elements, and redundant description thereof is omitted. Hereinafter, an axis parallel to the conveyance direction of the substrate is defined as an X axis, an axis orthogonal to the X axis in the horizontal plane (left and right in fig. 2) is defined as a Y axis, and an axis orthogonal to the horizontal plane (up and down in fig. 2) is defined as a Z axis.

First, a structure of a screen printing system 1, which is an example of a solder paste printing system according to an embodiment of the present disclosure, will be described with reference to fig. 1. The screen printing system 1 includes a management computer 3, a printer M1 and a print solder inspection device (hereinafter referred to as an inspection device) M2 connected in series from the upstream (left side of the drawing) toward the downstream (right side of the drawing) in the substrate conveying direction. The printer M1 and the inspection apparatus M2 are connected to the management computer 3 via the communication network 2. The management computer 3 stores production data including control programs and the like used in the respective devices, inspection result information, and the like, and transmits and receives information to and from the printer M1 and the inspection device M2.

The printer M1 prints solder paste on the substrate carried in from upstream through the opening provided in the screen mask. The inspection device M2 has an inspection camera, a 3-dimensional sensor, and the like. The inspection device M2 uses them to inspect the state of the solder paste printed on the upper surface of the substrate conveyed from the printer M1, the amount of the solder paste, and the like. The inspection result is sent to the management computer 3 and also to the printer M1. The screen printing system 1 is disposed upstream of a mounting substrate manufacturing line for mounting components on a substrate, and the substrate after the inspection by the inspection device M2 is carried to a component mounting device or the like disposed downstream thereof.

Next, the structure of the printer M1 will be described with reference to fig. 2. The printer M1 has a pair of conveyor belts 5 extending along the X axis on the base 4. The base 4 is provided with a print control unit C. The conveyor 5 is controlled by the printing control unit C to convey the substrate 6 received from the upstream side of the printer M1 along the X-axis operation position, and when the screen printing is completed, the substrate 6 is carried out to the downstream side of the printer M1. A substrate holding portion 7 controlled by the print control portion C is provided near the center of the conveyor 5 on the X axis. The substrate holding unit 7 receives the substrate 6 conveyed by the conveyor 5 and holds the substrate at a predetermined clamping position (working position).

A screen mask 8 is provided above the substrate holding portion 7. The screen mask 8 is provided with a plurality of openings 8a and mask marks (not shown) for printing the solder paste Pst on the substrate 6. The screen mask 8 has a rectangular flat plate shape extending in extension on a plane defined by the X axis and the Y axis, and its outer periphery is supported by the frame member 8 w.

An XY stage 9, a θ stage 10, and a substrate lifting mechanism 11 are provided in this order from below on the base 4. The XY stage 9 moves the θ stage 10 in the horizontal plane (along the X axis and the Y axis). The θ stage 10 rotates the substrate elevating mechanism 11 around the Z axis. The substrate lifting mechanism 11 supports the substrate holding unit 7 from below and moves it up and down as indicated by arrow a 1. The XY stage 9, the θ stage 10, and the substrate lifting mechanism 11 are controlled by the print control unit C.

Below the screen mask 8, a camera unit 13 incorporating a camera for substrate recognition and a camera for mask recognition is provided. The camera unit 13 moves in a horizontal plane as indicated by an arrow a2 by a 1 st moving mechanism 14 described later with reference to fig. 6. The 1 st moving mechanism 14 is controlled by the printing control unit C. The camera unit 13 moves between the substrate 6 and the screen mask 8, and photographs a substrate mark for alignment formed on the substrate 6 and a mask mark for alignment formed on the screen mask 8. The print control section C recognizes the position of the mask mark and the position of the substrate mark based on the image captured by the camera unit 13.

As shown in fig. 3A, a plurality of lands 6a are provided on the substrate 6. The print control unit C controls the XY stage 9, the θ stage 10, and the substrate lifting mechanism 11 based on the identification result of the mark. Then, the position and orientation of the substrate 6 with respect to the screen mask 8 are aligned in such a manner that the plurality of opening portions 8a formed on the screen mask 8 and the plurality of lands 6a on the substrate 6 held by the substrate holding portion 7 coincide. Next, the printing control unit C raises the substrate holding unit 7, and brings the substrate 6 into contact with the screen mask 8 from below. In this way, the XY stage 9, the θ stage 10, and the substrate elevating mechanism 11 constitute the positioning mechanism 12. The positioning mechanism 12 moves the substrate holding portion 7 so as to position-align the substrate 6 held by the substrate holding portion 7 with the screen mask 8.

A print head 20 is provided above the screen mask 8. The print head 20 is moved along the Y axis as indicated by an arrow a3 by a 2 nd moving mechanism 15 described later with reference to fig. 6. The print head 20 includes a moving base 21 that moves in a horizontal plane by the 2 nd moving mechanism 15. The 2 squeegee holding sections 22 are arranged in the Y-axis direction on the movable base 21. The squeegee holding portions 22 hold squeegees 23 extending along the X-axis at the lower ends thereof, respectively, and are moved up and down as indicated by arrow a4 by a lifting mechanism 24 provided to the movement base 21. The 2 nd moving mechanism 15 and the printing head 20 are controlled by the printing control unit C.

A cleaning mechanism 30 for cleaning the solder paste Pst remaining on the back surface of the screen mask 8 and in the opening 8a is provided below the screen mask 8 at the negative position (front side) of the Y axis. The cleaning mechanism 30 is moved along the Y axis as indicated by an arrow a5 by a3 rd movement mechanism 16 described later with reference to fig. 6. The 3 rd movement mechanism 16 is controlled by the printing control unit C. The cleaning mechanism 30 has a wiping head 31. The wiping head 31 extends along the X axis and moves along the Z axis as indicated by arrow a 6.

In the cleaning mechanism 30, a paper roll 33A on which the unused cleaning paper 32 is wound and a paper roll 33B on which the used cleaning paper 32 is recovered are respectively mounted on the front and rear sides of the wiper head 31 on the Y axis. The cleaning paper 32 pulled out from the paper roll 33A passes over the upper surface of the wiping head 31 while sliding, and is wound on the paper roll 33B. The paper roll 33B is rotated by a roll rotation mechanism 34 controlled by the print control unit C. The cleaning mechanism 30 further has an application portion 35. The application unit 35 is controlled by the print control unit C, and applies a solvent for dissolving the flux contained in the solder paste Pst to the cleaning paper 32.

When the solder paste Pst remaining in the screen mask 8 is cleaned, the printing control unit C cleans the screen mask 8 in a wet cleaning method or a dry cleaning method in a predetermined pattern. In the wet cleaning method, the printing control unit C lifts the cleaning paper 32 coated with the solvent by the coating unit 35 using the wiping head 31. Thereby, the cleaning paper 32 is brought into contact with the back surface of the screen mask 8, and the cleaning mechanism 30 is moved along the Y axis. Thus, the print control unit C wipes the residual solder paste Pst. In the dry cleaning method, the printing control unit C lifts the cleaning paper 32, which is not coated with the solvent, by the wiping head 31 and makes it contact with the back surface of the screen mask 8. Then, the cleaning mechanism 30 is moved along the Y axis, and the remaining solder paste Pst is wiped.

Next, a printing process (printing operation) of printing the solder paste Pst on the substrate 6 by the printer M1 will be described with reference to fig. 3A to 3C. As shown in fig. 3A, a plurality of lands 6a as electrodes are formed on the upper surface of the substrate 6. A stopper 6b as an insulator is formed on the upper surface of the substrate 6 except for the land 6a. The substrate 6 is moved below the screen mask 8 and held by the substrate holding portion 7. In the printing step, first, the printing control unit C controls the positioning mechanism 12 shown in fig. 2 to position the substrate 6 with respect to the screen mask 8. Next, the printing control unit C raises the substrate holding unit 7 as indicated by an arrow b1, and brings the substrate 6 into contact with the lower surface of the screen mask 8.

Next, as shown in fig. 3B, the printing control unit C lowers the squeegee 23 to be abutted against the screen mask 8, and then slides along the Y axis as shown by an arrow B2. By this sliding, the solder paste Pst supplied to the screen mask 8 is pushed into the opening 8a, and transferred to the substrate 6. In this transfer step, the print control unit C transfers the solder paste Pst to the substrate 6 under predetermined printing conditions. The given printing conditions include a pressure (printing pressure) at which the squeegee 23 is pressed against the screen mask 8 and a speed at which the squeegee 23 is moved.

As shown in fig. 3C, the printing control unit C then separates the substrate 6 from the screen mask 8 while lowering the substrate holding unit 7 as indicated by an arrow b 3. In this deviating step, the printing control unit C separates the substrate 6 from the screen mask 8 under deviating conditions in which the substrate 6 is lowered at a predetermined lowering speed. Thereby, the solder paste Pst is printed (deposited) on the land 6a of the substrate 6. The solder paste Pst contains solder particles S and flux F, and when printed on the substrate 6, the flux F having fluidity oozes out to the outer periphery of the deposit of the solder particles S. In this way, the printer M1 prints the solder paste Pst containing the solder particles S and the flux F on the substrate 6 through the opening 8a provided in the screen mask 8.

Next, the structure of the inspection apparatus M2 will be described with reference to fig. 4. The inspection apparatus M2 has a pair of conveyor belts 41 extending along the X axis on the base 40. The conveyor 41 conveys the printed substrate (hereinafter also referred to as substrate) 6P received from the upstream printer M1 to the inspection position along the X axis, and when the inspection is completed, the substrate is carried out downstream of the inspection device M2. A substrate holding portion 42 is provided near the center of the conveyor 41 in the X axis. The substrate holding portion 42 receives the substrate 6P conveyed by the conveyor 41 and holds it at a predetermined clamping position (inspection position). The substrate holding portion 42 is provided with a gauge 43 for measuring the weight of the substrate 6.

An inspection head 44 is provided above the substrate holding portion 42. The inspection head 44 is moved in a horizontal plane by a moving mechanism 45 described later with reference to fig. 7. The inspection head 44 includes an inspection camera (hereinafter referred to as a camera) 46, a 1 st illumination section 47, a 2 nd illumination section 48, and a height detection section 49. The camera 46 is disposed with the optical axis 46a facing downward, moves above the substrate 6 held by the substrate holding portion 42, and photographs the solder paste Pst printed on the substrate 6.

The 1 st illumination unit 47 is disposed around the camera 46, and illuminates a portion of the substrate 6 imaged by the camera 46. The 2 nd illumination unit 48 is disposed around the camera 46 and is located outside the 1 st illumination unit 47 when viewed from the camera 46, and illuminates a portion on the substrate 6 imaged by the camera 46. That is, the 2 nd illumination light 48a irradiated from the 2 nd illumination portion 48 is inclined with respect to the substrate 6 as compared with the 1 st illumination light 47a irradiated from the 1 st illumination portion 47.

In the inspection apparatus M2, the 1 st illumination section 47 and the 2 nd illumination section 48 are switched or used simultaneously according to the object photographed by the camera 46. Alternatively, the intensity of the 1 st illumination light 47a irradiated from the 1 st illumination section 47 and the intensity of the 2 nd illumination light 48a irradiated from the 2 nd illumination section 48 are changed according to the object photographed by the camera 46. The height detection unit 49 includes a 3D sensor or the like, moves above the substrate 6 held by the substrate holding unit 42, irradiates the measurement light 49a, and measures the position of the solder paste Pst printed on the substrate 6 and the shape of the height including the solder paste Pst, thereby detecting the state of the solder paste Pst printed on the substrate 6.

Next, an example of an image obtained by capturing an image of the substrate 6P printed with the solder paste Pst in the printer M1 with the camera 46 of the inspection apparatus M2 will be described with reference to fig. 5A and 5B. Fig. 5A shows an image 50 obtained by capturing a position on the substrate 6 with the camera 46 while the 1 st illumination 47a is irradiated from the 1 st illumination section 47, and fig. 5B shows an image 51 obtained by capturing a position on the substrate 6 with the camera 46 while the 2 nd illumination 48a is irradiated from the 2 nd illumination section 48. In fig. 5A, the solder paste Pst is printed in a columnar shape through a circular opening 8a formed in the screen mask 8 on the land 6a formed on the upper surface of the substrate 6.

In the image 50 obtained by photographing while irradiating the 1 st illumination light 47a, the deposit of the solder particles S contained in the solder paste Pst is photographed in addition to the boundary between the land 6a and the dam 6b on the substrate 6. In fig. 5B, in an image 51 obtained by photographing while irradiating the 2 nd illumination light 48a, the solder paste Pst contains the flux F in addition to the boundary between the land 6a and the dam 6B on the substrate 6 and the deposit of the solder particles S. The flux F oozes out from the deposit of solder particles S printed on the substrate 6. Thus, by obliquely irradiating the 2 nd illumination light 48a, the state of the flux F on the substrate 6 can be detected.

In this way, the camera 46 and at least one illumination unit (1 st illumination unit 47, 2 nd illumination unit 48) for illuminating the substrate 6 imaged by the camera 46 function as detection units for detecting the solder particles S and the flux F of the solder paste Pst printed on the substrate 6. The inspection device M2 inspects the state of the solder paste Pst printed on the substrate 6. That is, the detection unit is provided in the inspection device M2 included in the screen printing system 1.

Next, the configuration of the control system of the printer M1 will be described with reference to fig. 6. The printing control unit C of the printer M1 is connected to the conveyor belt 5, the substrate holding unit 7, the positioning mechanism 12, the camera unit 13, the 1 st moving mechanism 14, the 2 nd moving mechanism 15, the 3 rd moving mechanism 16, the touch panel 17, the print head 20, and the cleaning mechanism 30. The touch panel 17 has a display function of displaying an operation screen or the like of the printer M1 on the liquid crystal panel, and an input function of inputting instructions, various information, or the like by operating the displayed operation screen. Instead of the touch panel 17, a display device such as a liquid crystal panel and an input device such as a mouse and a switch may be provided.

The print control unit C includes a storage unit 60, a 1 st processing unit 61, a 2 nd processing unit 62, a plan management unit 63, a 3 rd processing unit 64, and a communication unit 65. The communication unit 65 is a network communication device, and transmits and receives information to and from the management computer 3 and the inspection device M2 via the communication network 2. The storage unit 60 is a storage device including a rewritable RAM (random access memory) or the like. The storage unit 60 stores, for each type of substrate 6, printing conditions for printing the solder paste Pst on the substrate 6 by the print head 20, mask cleaning conditions for performing mask cleaning, and the like.

As described above, the printing conditions include the pressure (printing pressure) at which the squeegee 23 presses the solder paste Pst into the plurality of openings 8a, the moving speed of the squeegee 23 at the time of printing, the deviating speed at which the substrate 6 is separated from the screen mask 8 after printing, and the like. Further, the mask cleaning conditions include timing of performing mask cleaning, cleaning mode (wet cleaning, dry cleaning), and the like.

The 1 st processing unit 61, the 2 nd processing unit 62, the schedule management unit 63, and the 3 rd processing unit 64 are each constituted by a CPU (central processing unit) or an LSI (large scale integrated circuit). Alternatively, the present invention may be realized by a dedicated circuit or by controlling general-purpose hardware by software read from a volatile or nonvolatile memory device. Further, two or more of these may be integrally formed.

The 1 st processing unit 61 controls each section of the printer M1 including the print head 20 based on the printing conditions stored in the storage unit 60 to execute the print job. The 2 nd processing unit 62 controls the cleaning mechanism 30 and the 3 rd moving mechanism 16 to perform mask cleaning in accordance with a command (instruction) from the schedule management unit 63. The schedule management section 63 instructs the 2 nd processing section 62 based on the mask cleaning conditions stored in the storage section 60 so that the mask cleaning is performed in a given manner after the print job of the given number of substrates 6.

An example of the normal cleaning process will be described with reference to fig. 11. The schedule management unit 63 has a counter function, and counts the number of printing sheets of the substrate 6 after wet cleaning in the normal cleaning process. Then, as shown in the horizontal axis and the upper part of the figure, when 4 sheets (1 st to 4 th sheets) are printed on the substrate 6, the schedule management unit 63 causes the 2 nd processing unit 62 to perform dry cleaning. When 4 sheets (5 th to 8 th sheets) are printed on the substrate 6, the schedule management unit 63 causes the 2 nd processing unit 62 to execute dry cleaning again. When the 4 sheets (the 9 th to 12 th sheets) are printed on the substrate 6, the schedule management section 63 causes the 2 nd processing section 62 to perform wet cleaning, and then resets the counter.

In fig. 6, when a defect is detected in the printing state determination process or the flux state determination process in the inspection apparatus M2 described later, the 3 rd processing unit 64 changes the printing conditions stored in the storage unit 60 to improve the state of the solder paste Pst printed on the substrate 6.

Next, the configuration of the control system of the inspection apparatus M2 will be described with reference to fig. 7. The inspection control unit 70 included in the inspection apparatus M2 is connected to the conveyor 41, the substrate holding unit 42, the gauge 43, the moving mechanism 45, the camera 46, the 1 st illumination unit 47, the 2 nd illumination unit 48, the height detection unit 49, and the touch panel 76. The touch panel 76 has a display function of displaying an operation screen or the like of the inspection device M2 on the liquid crystal panel, and an input function of inputting instructions, various information, or the like by operating the displayed operation screen. The touch panel 76 is also dripped in the same manner as the touch panel 17, and may be replaced with a display device and an input device which are separately provided.

The inspection control unit 70 includes a 1 st storage unit 71, a 2 nd storage unit 72, an inspection processing unit 73, a flux state determination unit (hereinafter referred to as a determination unit) 74, and a communication unit 75. The communication unit 75 is a network communication device, and transmits and receives information to and from the management computer 3 and the printer M1 via the communication network 2. The 1 st storage unit 71 and the 2 nd storage unit 72 are storage devices. The 1 st storage unit 71 stores inspection conditions including the weight of the substrate 6 before printing, the inspection position of the solder paste Pst printed on the substrate 6, the inspection standard, and the like, for each type of the substrate 6. The 2 nd storage unit 72 stores data of an image (hereinafter simply referred to as an image) captured by the camera 46, and inspection results including the detected states of the solder particles S and the flux F, and the like. The 1 st storage unit 71 and the 2 nd storage unit 72 also include a rewritable RAM, flash memory, hard disk, and the like, similarly to the storage unit 60.

The inspection processing section 73 and the determination section 74 are constituted by a CPU (central processing unit) or an LSI (large scale integrated circuit). Alternatively, the present invention may be realized by a dedicated circuit or by controlling general-purpose hardware by software read from a volatile or nonvolatile memory device. Further, two of these may be integrally formed.

The inspection processing unit 73 controls the camera 46, the 1 st illumination unit 47, and the 2 nd illumination unit 48 so that the camera 46 captures an image of the upper side of the substrate 6 while the 1 st illumination light 47a or the 2 nd illumination light 48a is being irradiated. Further, the inspection processing section 73 processes the captured image and detects the solder particles S and the flux F printed on the substrate 6. The detection result is stored in the 2 nd storage unit 72. That is, the 2 nd storage unit 72 stores the detection results of the detection unit including the camera 46, the 1 st illumination unit 47, and the 2 nd illumination unit 48.

The inspection processing unit 73 controls the weighing device 43 to measure the weight of the printed substrate 6P carried into the substrate holding unit 42. The measurement result is stored in the 2 nd storage unit 72.

The inspection processing unit 73 controls the height detecting unit 49 to measure the 3-dimensional shape of the solder paste Pst printed on the substrate 6. Thus, the inspection processing section 73 detects the solder particles S and the flux F based on the height of the solder paste Pst from the land 6a, the height of the solder paste Pst from the dam 6b, the difference in height between the deposit of the solder particles S and the flux F, and the like. The detection result is stored in the 2 nd storage unit 72. That is, the height detecting section 49 functions as a detecting section for detecting the solder particles S and the flux F of the solder paste Pst printed on the substrate 6.

Here, a state of the screen mask 8 after the printing operation will be described with reference to fig. 8A to 8D. Fig. 8A shows a state of the screen mask 8 before printing or immediately after wet cleaning is performed, with the solder paste Pst removed from the opening portion 8A and the lower surface of the screen mask 8. Fig. 8B to 8D schematically show the state of the screen mask 8 after the printing work is repeatedly performed without performing mask cleaning. After the printing operation, the residues such as the solder particles S and the flux F adhere to the opening 8a and the lower surface of the screen mask 8, and the amount of the residues increases by repeating the printing operation.

Next, an example of an image obtained by photographing the upper side of the substrate 6 on which the solder paste Pst is printed by the camera 46 will be described with reference to fig. 5A, 5B, 9A, 9B, 10A, and 10B. Fig. 9A, 9B, 10A, and 10B capture the same positions on the substrate 6 as fig. 5A and 5B. In fig. 5A and 5B, printing is performed through the screen mask 8 immediately after wet cleaning is performed as shown in fig. 8A, and in fig. 10A and 10B, the number of times of repeated execution of the printing job is increased as compared with fig. 9A and 9B. For example, in fig. 9A and 9B, a printing operation is performed by the screen mask 8 in the state shown in fig. 8C, and in fig. 10A and 10B, a printing operation is performed by the screen mask 8 in the state shown in fig. 8D. The image 52 shown in fig. 9A and the image 54 shown in fig. 10A are obtained by capturing the 1 st illumination light 47a from the 1 st illumination unit 47. The image 53 shown in fig. 9B and the image 55 shown in fig. 10B are obtained by capturing the 2 nd illumination light 47a from the 2 nd illumination unit 48.

As is clear from these figures, as the residue adhering to the screen mask 8 increases, the shape of the deposit of solder particles S printed on the substrate 6 breaks down, and the solder particles S spread horizontally. In addition, the area of the flux F oozing out from the solder particles S also increases. The position indicated by the dashed circle c in the image 54 of fig. 10A creates a "solder bridge". That is, the deposit of solder particles S printed on the land 6a spreads and is connected to the deposit of adjacent solder particles S. In the image 55 of fig. 10B, the flux F connects the adjacent two lands 6 a.

In this way, if the residue of the screen mask 8 increases, the amount of the flux F printed on the substrate 6 increases. Further, by observing the state of the flux F (flux state) printed on the substrate 6, it can be predicted that a printing failure such as a solder bridge will occur when the printing operation is continued.

In fig. 7, the determination unit 74 determines whether the state of the flux F on the substrate 6 is good or bad based on the images 51, 53, 55 captured by the camera 46 while the 2 nd illumination light 48a is being irradiated. For example, the determination unit 74 calculates the area (flux amount) of the printed flux F, and determines that the state of the flux F is good when the area is within the reference (threshold value). If the reference value is exceeded, it is determined that the state of the flux F is poor. The determination unit 74 may determine whether the state of the flux F is good or bad based on the shape of the flux F, in addition to the area of the printed flux F.

Here, an example in which the determination unit 74 determines whether the state of the flux F is good or bad will be described with reference to fig. 11. Fig. 11 is a graph showing the flux amounts of the fluxes F detected from the images 51, 53, 55 in the order of the printed board 6. The white circles connected by the solid line d schematically represent the normal shift of the solder amount on the substrate 6. That is, the amount of flux gradually increases after wet cleaning until the next wet cleaning (1 st to 12 th sheets), the amount of flux gradually decreases after dry cleaning (5 th and 9 th sheets), and the amount of flux decreases at once after wet cleaning (13 th sheets). Thus, in the normal state, wet cleaning is performed before the amount of flux exceeds the threshold.

The black circles connected by the one-dot chain line e indicate a case where the residue of the solder paste Pst remaining in the screen mask 8 after the printing operation increases faster than in the normal state, and the amount of flux exceeds the threshold value in the substrate 6 of the 7 th sheet. In this case, the determination unit 74 determines that the solder state of the 7 th substrate 6 is poor.

The open triangles joined by the broken line f show that the residues of the solder paste Pst are largely adhered to the screen mask 8 after the printing work of the 6 th substrate 6, and the flux amount of the 7 th substrate 6 is sharply increased although it is within the threshold value. In this case, the determination unit 74 predicts that the flux amount exceeds the threshold value after the 8 th sheet based on the flux amount of the 6 th sheet and the flux amount of the 7 th sheet, and the flux state becomes poor. That is, the determination unit 74 determines the state of the flux F based on the last detection result (the 6 th chip) stored in the 2 nd storage unit 72 and the current detection result (the 7 th chip) detected by the detection unit.

The determination unit 74 shown in fig. 7 determines the state of the flux F from the image captured by the camera 46. The determination unit 74 may determine the state of the flux F based on the flux amount of the flux F detected by the height detection unit 49. The determination unit 74 may calculate the weight of the printed solder paste Pst from the weight of the substrate 6 before printing stored in the 1 st storage unit 71 and the weight of the substrate 6 after printing measured by the meter 43. Further, the determination unit 74 may calculate the weight of the flux F by subtracting the weight of the solder particles S calculated from the image of the solder particles S captured by the camera 46 from the weight of the printed solder paste Pst.

That is, the determination unit 74 may determine the state of the flux F based on the weight of the substrate 6 before and after printing the solder paste Pst. In this way, the meter 43 and the camera 46 function as detection units for detecting the solder particles S and the flux F of the solder paste Pst printed on the substrate 6. Then, the determination unit 74 determines whether the state of the flux F is good or bad based on the detection results of the detection units (the camera 46, the 1 st illumination unit 47, the 2 nd illumination unit 48, the gauge 43, and the height detection unit 49). The determination result is transmitted to the management computer 3 and the printer M1.

When the determination result that the state of the flux F is poor (for example, the flux amount exceeds the threshold value) is received from the determination unit 74 of the inspection apparatus M2, the schedule management unit 63 shown in fig. 6 instructs the 2 nd processing unit 62 to perform wet cleaning, and then resets the counter. In addition, in the case where the printing work on the subsequent substrate 6 has already been started, wet cleaning may be performed after the printing of the substrate 6 in the work.

Specifically, a black circle shown in fig. 11 is taken as an example for explanation. When the determination unit 74 determines that the state of the flux F of the 7 th substrate 6 is defective, the determination result of the defect is transmitted to the printer M1. In the printer M1, the plan manager 63 instructs the 2 nd process unit 62 to perform wet cleaning, and resets the counter. Then, in the printer M1, wet cleaning is performed before a print job is performed on the 8 th sheet of the substrate 6. If the wet cleaning is performed, the solder particles S and the flux F adhering to the screen mask 8 are removed, and the state of the solder paste Pst printed on the substrate 6 is improved.

That is, if the determination unit 74 determines that the state of the flux F is poor, the printer M1 performs an operation of changing the state of the flux F of the solder paste Pst printed on the substrate 6. In this case, the operation of changing the state of the flux F in the printer M1 is cleaning (wet cleaning) of the screen mask 8 by the cleaning mechanism 30 provided in the printer M1. This can prevent the printing state of the solder particles S from becoming worse.

When the determination result indicating that the state of the flux F is poor is transmitted from the determination unit 74, the 3 rd processing unit 64 shown in fig. 6 may change the printing conditions stored in the storage unit 60. That is, the operation of changing the state of the flux F of the solder paste Pst printed on the substrate 6 by the determination unit 74 determining that the state of the flux F is defective may be a change (update) of the printing condition.

That is, the conditions under which the printer M1 brings the substrate 6 into contact with the screen mask 8 to transfer the solder paste Pst to the substrate 6, the conditions under which the printer M1 separates the substrate 6 from the screen mask 8 after transferring the solder paste Pst to the substrate 6, and the like may be changed. More specifically, the printing pressure, the moving speed of the squeegee 23, the deviating speed, and the like can be changed. This can prevent the printing state of the solder particles S from becoming worse. The printing conditions need not be changed every time the determination result of poor solder conditions is received. For example, the printing conditions may be changed when a defect is generated twice in succession in normal cleaning or when the occurrence of a defect exceeds a predetermined frequency.

In the above-described embodiment, the explanation was given taking the case where the determination unit 74 is provided in the inspection apparatus M2 and the plan management unit 63 and the 3 rd processing unit 64 are provided in the printer M1 as an example, but the screen printing system 1 is not limited to this embodiment. For example, the management computer 3 may have a determination unit 74, a plan management unit 63, and a 3 rd processing unit 64. The printer M1 may have a meter 43 for measuring the weight of the substrate 6 before and after printing.

Next, a screen printing method in the screen printing system 1 will be described along fig. 12 and 13. In fig. 12, first, a substrate 6 is carried into a printer M1 of the screen printing system 1 by a conveyor 5 (ST 1). Next, the substrate holding unit 7 holds the substrate 6, and the positioning mechanism 12 aligns the substrate 6 with respect to the screen mask 8 (ST 2) and brings the substrate 6 into contact with the screen mask 8 (ST 3). Next, the print head 20 transfers the solder paste Pst to the substrate 6 in contact with the screen mask 8 via the screen mask 8 (ST 4), and then the substrate lift mechanism 11 separates the substrate 6 from the screen mask 8 (ST 5).

Thereby, the solder paste Pst is printed on the substrate 6, and the printed substrate 6P is manufactured. That is, ST2 to ST5 are printing steps for printing the solder paste Pst on the substrate 6 (ST 30). Next, the printed substrate 6P is transferred to the inspection apparatus M2 (ST 6). Next, at least one illumination unit (1 ST illumination unit 47 and 2 nd illumination unit 48) illuminates the substrate 6P (ST 7), and the camera 46 captures a solder paste Pst printed on the substrate 6 (ST 8). Next, the inspection processing unit 73 recognizes the captured image to identify the solder particles S and the flux F of the solder paste Pst printed on the substrate 6 (ST 9).

Next, the meter 43 measures the weight of the substrate 6P after the solder paste Pst is printed (ST 10). In this way, ST7 to ST10 are detection steps for detecting the solder particles S and the flux F of the solder paste Pst printed on the substrate 6 (ST 31). The detection result in the detection step (ST 31) is stored in the 2 nd storage unit 72 (ST 11).

Next, in fig. 13, the inspection processing unit 73 determines whether the state of the solder particles S is good or bad based on the image captured in ST8 (ST 12). If the print status is defective (defective in ST 12), the result is transmitted to the downstream component mounting apparatus. In the printer M1, defective printing processing such as cleaning (dry cleaning) of the screen mask 8 and changing of printing conditions is performed (ST 13). When the printing state is good (good in ST 12) and when the printing state is bad and the printing failure processing is performed (ST 13), the substrate 6P is then carried out from the screen printing system 1 (ST 14).

When the production of the printed circuit board 6P is not completed (no in ST 15), the determination unit 74 determines whether or not the state of the flux F of the inspected printed circuit board 6P exceeds a predetermined reference, that is, whether or not the flux state is poor, based on the detection result in the detection step (ST 31) (ST 16). The determination unit 74 may determine the state of the flux F based on the stored last detection result and the current detection result detected in the detection step (ST 31). Specifically, the determination unit 74 determines the state of the flux F from the image captured in ST 8. The determination unit 74 may determine the state of the flux F based on the weight of the substrate 6 before printing and the weight after printing measured in ST 10.

If it is determined in ST16 that the state of the flux F is poor, the schedule management section 63 causes the 2 nd processing section 62 to perform wet cleaning (ST 17), and resets the counter to zero (ST 18). Next, the 3 rd processing unit 64 changes the printing conditions stored in the storage unit 60 (ST 19). Thereby, the conditions for transferring the solder paste Pst to the substrate 6 in ST4 and/or the conditions for separating the substrate 6 from the screen mask 8 in ST5 are changed.

In this way, from ST17 to ST19, if it is determined in ST16 that the state of the flux F is poor, a change operation step of changing the state of the flux F of the solder paste Pst printed on the substrate 6 is performed (ST 32). This can prevent printing failure.

If it is determined in ST16 that the state of the flux F is good, the schedule management section 63 performs normal cleaning in accordance with the count of the counter (ST 20). After the change operation step (ST 32) or the normal cleaning process (ST 20), the process returns to ST1 and the next substrate 6 is carried in.

As described above, the screen printing system 1 has the printer M1. The screen printing system 1 includes a detection unit that detects the solder particles S and the flux F of the solder paste Pst printed on the substrate 6, and a determination unit 74 that determines whether or not the state of the flux F is good based on the detection result of the detection unit. Then, if the determination unit 74 determines that the state of the flux F is poor, the printer M1 performs an operation of changing the state of the flux F of the solder paste Pst printed on the substrate 6. This can prevent printing failure. The detection unit may be capable of detecting the state of the flux F of the solder paste Pst. Therefore, the detection unit does not need to have all of the camera 46, the 1 st illumination unit 47, the 2 nd illumination unit 48, the gauge 43, and the height detection unit 49. For example, if the detection unit is capable of detecting the state of the flux F by at least one of the camera 46, the 1 st illumination unit 47, and the 2 nd illumination unit 48, the meter 43 and the height detection unit 49 may not be provided.

In the above embodiment, the example of the trigger of feeding back the state of the flux F to the execution of cleaning of the screen mask 8 and the change of the printing conditions in the screen printing has been described. However, the determination of whether the state of the flux F is good or bad is not limited to these uses. For example, when the solder portion is formed on the land 6a by a method other than screen printing, the method may be used to determine the formation state of the solder portion. Further, an operation of changing the state of the flux of the solder paste may be performed in this method based on the determination result.

Industrial applicability

The solder paste printing system and the solder paste printing method of the present disclosure have the effect of being able to prevent printing failure, and are useful in the field of mounting electronic components on a substrate.

Symbol description

1. A screen printing system;

2. a communication network;

3. a management computer;

4. a 40 base station;

5. 41 conveyor belt;

6. a substrate;

6a connecting disc;

6b barrier;

a 6P printed substrate (substrate);

7. a substrate holding section;

8. a screen mask;

8a opening portions;

8w frame members;

9 XY stations;

10. θ table;

11. a substrate lifting mechanism;

12. a positioning mechanism;

13. A camera unit;

14. a 1 st moving mechanism;

15. a 2 nd moving mechanism;

16. a 3 rd movement mechanism;

17. 76 touch panel;

20. a print head;

21. a moving base;

22. a blade holding section;

23. a scraper;

24. a lifting mechanism;

30. a cleaning mechanism;

31. a wiping head;

32. cleaning paper;

33A, 33B paper rolls;

35. a coating section;

42. a substrate holding section;

43. a gauge;

44. an inspection head;

45. a moving mechanism;

46. inspection cameras (cameras);

46a optical axis;

47. a 1 st illumination unit;

47a 1 st illumination light;

48. a 2 nd illumination unit;

48a, 2 nd illumination light;

49. a height detection unit;

49a, measuring light;

50. 51, 52, 53, 54, 55 images;

60. a storage unit;

61. a 1 st processing unit;

62. a 2 nd processing unit;

63. a plan management unit;

64. a 3 rd processing unit;

65. 75 communication part;

70. an inspection control unit;

71. a 1 st storage unit;

72. a 2 nd storage unit;

73. an inspection processing unit;

74. a flux state determination unit (determination unit);

a printing control unit;

f, welding flux;

m1 printing machine;

m2 print solder inspection device (inspection device);

pst solder paste;

s solder particles.

Claims

1. A solder paste printing system is provided with:

a printer that prints a solder paste containing solder particles and a flux on a substrate;

A detection unit configured to detect the solder particles and the flux of the solder paste printed on the substrate; and

a flux state determination unit configured to determine whether the state of the flux contained in the solder paste is good or bad based on a detection result of the detection unit,

if the solder state determination unit determines that the state of the solder paste is poor, the printer performs an operation of changing the state of the solder paste before printing the solder paste on the unprinted substrate,

the detection unit includes:

a camera for photographing the solder paste printed on the substrate;

a 1 st illumination unit configured to irradiate the 1 st illumination light to the substrate;

a 2 nd illumination unit configured to irradiate the substrate with a 2 nd illumination light, the 2 nd illumination light being inclined with respect to the substrate as compared with the 1 st illumination light,

detecting the solder particles based on the 1 st image captured by the camera while irradiating the 1 st illumination light,

the flux is detected based on the 2 nd image captured by the camera while the 2 nd illumination light is irradiated.

2. The solder paste printing system of claim 1, wherein,

the device further comprises: a storage unit configured to store the detection result of the detection unit,

The flux state determination unit determines the state of the flux based on the last detection result stored in the storage unit and the current detection result detected by the detection unit.

3. The solder paste printing system of claim 1 or 2, wherein,

the flux state determination unit determines the state of the flux based on the 2 nd image.

4. The solder paste printing system of claim 3, wherein,

the flux state determination unit determines that the state of the flux is poor based on a determination result that the area of the flux printed on the substrate in the 2 nd image exceeds a reference.

5. The solder paste printing system of claim 1 or 2, wherein,

the detection unit includes: a meter for measuring a weight before printing the solder paste on the substrate and a total weight of the substrate and the solder paste after printing the solder paste, that is, a weight after printing,

the flux state determination unit determines the state of the flux based on the pre-printing weight and the post-printing weight.

6. The solder paste printing system of claim 5, wherein,

the flux state determination unit determines that the state of the flux is poor based on a determination result that an amount of the flux obtained from a difference between the pre-printing weight and the post-printing weight exceeds a threshold value.

7. The solder paste printing system of claim 3, wherein,

the device further comprises: a printing solder inspection device for inspecting the state of the solder paste printed on the substrate,

the detection part is arranged on the printing solder inspection device.

8. The solder paste printing system of claim 1 or 2, wherein,

the printer comprises: a screen mask provided with openings for printing the solder paste on the substrate; and a cleaning mechanism for cleaning the screen mask,

the operation of changing the state of the flux in the printer is cleaning of the screen mask by the cleaning mechanism.

9. The solder paste printing system of claim 1 or 2, wherein,

the printer comprises: a screen mask provided with openings for printing the solder paste on the substrate,

in the operation of changing the state of the flux in the printer, conditions under which the printer brings the unprinted substrate into contact with the screen mask to transfer the solder paste on the screen mask to the unprinted substrate are changed.

10. The solder paste printing system of claim 1 or 2, wherein,

the operation of changing the state of the flux in the printer is to change a condition of separating the unprinted substrate from the screen mask after the solder paste is transferred to the unprinted substrate by the printer.

11. A method of solder paste printing comprising:

a step of printing a solder paste containing solder particles and a flux on a substrate;

a step of detecting the solder particles and the flux of the solder paste printed on the substrate, and obtaining a detection result;

a step of determining whether the state of the flux contained in the solder paste is good or bad based on the detection result; and

a step of performing an operation of changing the state of the flux of the solder paste before printing the solder paste on an unprinted substrate if it is determined that the state of the flux is poor,

in the case of the determination of the result of the detection,

detecting the solder particles based on a 1 st image obtained by photographing the solder paste printed on the substrate by a camera while the 1 st illumination light is irradiated on the substrate by the 1 st illumination part,

The flux is detected based on a 2 nd image obtained by photographing the solder paste printed on the substrate by the camera while the 2 nd illumination light is irradiated to the substrate by the 2 nd illumination portion, the 2 nd illumination light being inclined with respect to the substrate as compared with the 1 st illumination light.

12. The solder paste printing method according to claim 11, wherein,

further comprising the step of storing the detection result,

whether the state of the flux is good or bad is determined based on the stored last detection result and the detected current detection result.

13. The solder paste printing method according to claim 11 or 12, wherein,

a state of the flux is determined based on the 2 nd image captured.

14. The solder paste printing method according to claim 11 or 12, wherein,

when the detection result is obtained, the weight before printing the substrate before printing the solder paste and the total weight of the substrate and the solder paste after printing the solder paste, namely the weight after printing are measured,

the state of the flux is determined based on the pre-print weight and the post-print weight.

15. The solder paste printing method according to claim 11 or 12, wherein,

The solder paste is printed on the substrate via a screen mask provided with openings,

the operation of changing the state of the flux is cleaning of the screen mask.

16. The solder paste printing method according to claim 11 or 12, wherein,

when the solder paste is printed on the substrate, the solder paste is transferred on the substrate in contact with a screen mask provided with an opening through the screen mask,

the operation of changing the state of the flux is to change conditions under which the solder paste is transferred to the unprinted substrate.

17. The solder paste printing method according to claim 11 or 12, wherein,

after the substrate is transferred with the solder paste, the substrate is separated from the screen mask,

the operation of changing the state of the flux is to change a condition for separating the unprinted substrate from the screen mask.