DE112020004841T5 - Solder paste printing system and solder paste printing method - Google Patents

Abstract

A solder paste printing system includes a printer, a detector, and a flux condition determination unit. The printing system prints solder paste containing solder particles and flux onto a substrate. The detector detects the solder particles and flux of the solder paste printed on the substrate. The flux condition determination unit determines whether the condition of the flux is good or defective from the detection result obtained by the detector. If the flux state determination unit determines that the state of the flux is abnormal, then the printing system performs a process of changing the state of the flux of the solder paste before the solder paste is printed on an unprinted substrate.

Description

technical field

The present disclosure relates to a solder paste printing system and a solder paste printing method for printing solder paste onto a substrate.

State of the art

In a printing system, a lower surface of a screen mask provided with openings is brought into contact with a substrate. A squeegee then moves on the screen mask, solder paste containing solder particles and flux is pushed into the openings, and the solder paste is transferred to the substrate. The substrate on which the solder paste is printed is photographed by a camera. The presence of a print defect is determined from the photographed result. A print defect includes a condition in which the transferred solder paste joins with the adjacent solder paste material (solder bridge) and a condition in which the solder paste is missing at a required position (see, for example, PTL 1).

In a detection method described in the PTL 1, solder paste (cream-like solder colored so as to enhance the contrast with the substrate is employed, and the camera photographs the substrate on which the solder paste of such a kind is printed. Then, the presence of the print defect is obtained from the shape of the photographed solder paste by inspection, and when the print defect is detected, the screen mask is cleaned.

list of citations

patent literature

PTL 1: Japanese Unexamined Patent Publication No. H05-123892

Overview of the Invention

A solder paste printing system of the present disclosure includes a printer, a detector, and a flux condition determination unit. The printing system prints solder paste containing solder particles and flux material onto a substrate. The detector detects the solder particles and flux material of the solder paste printed on the substrate. The flux state determination unit determines whether the state of the flux is good or bad from the detection result obtained by the detector. When the flux state determination unit determines that the state of the flux is abnormal, the printing system performs a process of changing the state of the flux of the solder paste before the solder paste is printed on an unprinted substrate.

In a solder paste printing method of the present disclosure, solder paste containing solder particles and flux is printed onto a substrate. In the method, the solder particles and the flux of the solder paste printed on the substrate are detected to obtain a detection result. From this detection result, the condition of the flux is determined as good or faulty. When the state of the flux is determined to be abnormal, a process of changing a state of the flux of the solder paste is performed before the solder paste is printed on a non-printed substrate.

According to the present disclosure, a print defect can be prevented in advance.

character list

• 1 12 is a schematic configuration view of a screen printing system according to an illustrative embodiment of the present disclosure.
• 2 Fig. 12 is a structural view of a printing system in Fig 1 illustrated screen printing system.
• 3A Fig. 12 is a cross-sectional view showing a solder paste printing step through the Fig 2 shown pressure system shows.
• 3B 14 is a cross-sectional view showing a solder paste printing step subsequent to the step in FIG 3A indicates.
• 3C 14 is a cross-sectional view showing a solder paste printing step subsequent to the step in FIG 3B indicates.
• 4 FIG. 14 is a structural view of a printed solder inspecting device in FIG 1 illustrated screen printing system.
• 5A 13 is a view showing an example of an image obtained by first inspecting the substrate on which the solder paste is printed by a first irradiation unit of the printed solder inspecting apparatus disclosed in FIG 4 is irradiated, and the substrate is photographed with an inspection camera.
• 5B is a view showing an example of an image obtained by using the in 5A substrate shown by a second irradiation unit of the printed solder inspection apparatus disclosed in FIG 4 shown is irradiated and the substrate is photographed with the inspection camera.
• 6 FIG. 14 is a functional block view showing a control system of FIG 2 illustrated pressure system shows.
• 7 FIG. 14 is a functional block view showing a control system of FIG 4 illustrated printed solder inspector.
• 8A 13 is a cross-sectional view showing an example of a state of a screen mask before printing in FIG 2 illustrated pressure system shows.
• 8B 13 is a cross-sectional view showing an example of a state of the screen mask after printing in FIG 2 illustrated pressure system shows.
• 8C 13 is a cross-sectional view showing an example of a state of the screen mask after printing is performed more times than that in FIG 8B state shown occurred.
• 8D 13 is a cross-sectional view showing an example of a state of the screen mask after printing is performed more times than that in FIG 8C state shown occurred.
• 9A FIG. 14 is a view showing an example of an image obtained by using a substrate on which the solder paste is formed using the screen mask in FIG 8C shown state is printed by the first irradiation means of the printed solder inspecting means shown in FIG 4 is irradiated and the substrate is photographed with the inspection camera.
• 9B is a view showing an example of an image obtained by using the in 9A substrate shown by the second irradiation means of the printed solder inspection means disclosed in FIG 4 is irradiated and the substrate is photographed with the inspection camera.
• 10A FIG. 14 is a view showing an example of an image obtained by using a substrate on which the solder paste is formed using the screen mask in FIG 8D shown state is printed by the first irradiation device of the printed solder inspecting device shown in FIG 4 is irradiated and the substrate is photographed with the inspection camera.
• 10B is a view showing an example of an image obtained by using the in 10A substrate shown by the second irradiation means of the printed solder inspection means disclosed in FIG 4 is irradiated and the substrate is photographed with the inspection camera.
• 11 FIG. 14 is a view showing an example of a memory stored in a second storage unit of FIG 7 shown inspecting device for printed solder stored flux detection result.
• 12 FIG. 14 is a flowchart showing a portion of a screen printing method according to the illustrative embodiment of the present disclosure.
• 13 FIG. 14 is a flowchart showing another part of the screen printing method according to the illustrative embodiment of the present disclosure.

Description of the embodiment

Prior to describing an illustrative embodiment of the present disclosure, prior art leading to the development of the idea of the present disclosure will be briefly described. In the PTL 1, a print defect such as a solder bridge is detected from the shape of the entire colored solder paste. Therefore, it is not possible to judge whether the solder particles contained in the solder paste are bonded to each other or the flux is bonded. However, the solder particles and the flux have different fluidities. Therefore, the behavior of these two components before the occurrence of the print defect, such as the solder bridge, is also different. Therefore, there is still room for improvement in recognizing an indication of a print defect in the process of repeatedly performing a screen printing operation and taking appropriate corrective measures before the print defect occurs.

The present disclosure provides a solder printing system and a solder printing method that can prevent the printing defect in advance.

An illustrative embodiment of the present disclosure will now be described in detail with reference to the drawings. The constructions, shapes and the like described below are examples for description, and can be appropriately changed according to the requirements of a screen printing system, a printer, a printed solder inspection device and a control computer. Hereinafter, components that correspond to each other will be given identical reference numerals throughout the drawings, and repeated description will be omitted. In the following, an axis parallel to the transport direction of the substrate is defined as an X-axis, a Axis perpendicular to the X-axis in a horizontal plane (a left and right direction in 2 ) is defined as a Y-axis, and an axis perpendicular to the horizontal plane (an up and down direction in 2 ) is set as a Z-axis.

First, with reference to 1 A configuration of a screen printing system 1, which is an example of a solder paste printing system according to the exemplary embodiment of the present disclosure, will be described. The screen printing system 1 includes a management computer or control computer 3, a printer M1 and a printed solder inspection device (hereinafter inspection device) M2 arranged from the front (left on the sheet of the drawing) to the back (right on the sheet of the drawing) in the substrate transport direction in order are arranged. The printing system M1 and the inspection device M2 are connected to the management computer 3 via a communication network 2 . The management computer 3 stores production data containing a control program used in each facility, inspection result information and others, and sends and receives information to and from the printing facility M1 and the inspection facility M2.

The printer M1 prints solder paste on a substrate, which is fed in from the front, via an opening provided in a screen mask. The inspection device M2 includes an inspection camera, a three-dimensional sensor, and others. For example, the inspection device M2 inspects the state of the solder paste printed on the upper surface of the substrate fed from the printer M1 and inspects the amount of the solder paste using the camera and the sensor. The inspection result is transferred to the management computer 3 and is also transmitted to the printing system M1. The screen printing system 1 is arranged on the upstream side of the mounting substrate production line for mounting components on a substrate, and the substrate that has been inspected by the inspection device M2 is transported to the component mounter or the like arranged on the downstream side.

With reference to 2 a structure of a printing system M1 is then described. The printing system M1 has two transport units 5 as a pair, which extend along the X-axis on a base frame 4. A print controller C is provided on the base 4 . The transport units 5 are controlled by the printing controller C and transport a substrate 6 picked up from the upstream side of the printing machine M1 to a processing position along the X-axis, and when screen printing is completed, transport the substrate 6 to the downstream side of the printing system M1. In the area of the center of the X-axis of the transport units 5, a substrate holder 7, which is controlled by the print controller C, is provided. The substrate holder 7 receives the substrate 6 transported by the transport units 5 and holds the substrate 6 at a predetermined clamping position (processing position).

A screen mask 8 is mounted over the substrate holder 7. The screen mask 8 is provided with a plurality of openings 8a for printing solder paste Pst on the substrate 6, and includes a mask mark (not shown). The screen mask 8 has a rectangular flat plate shape extending in a plane formed by the X-axis and the Y-axis, and the outer edge is supported by a frame member 8w.

On the base 4, an XY stage 9, a θ stage 10, and a substrate elevating mechanism 11 are provided in this order from the lower side. 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. As indicated by the arrow a1, the substrate elevating mechanism 11 holds the substrate holder 7 from below and moves the substrate holder 7 up and down. The XY stage 9, the θ stage 10 and the substrate elevating mechanism 11 are controlled by the print controller C.

A camera unit 13 including a camera for substrate recognition and a camera for mask recognition is provided under the screen mask 8 . As indicated by the arrow a2, the camera unit 13 moves in the horizontal plane by a first moving mechanism 14 which will be described later with reference to FIG 6 is described. The first moving mechanism 14 is controlled by the print controller C. FIG. The camera unit 13 moves between the substrate 6 and the screen mask 8 , and captures photos of a substrate mark for alignment formed on the substrate 6 and a mask mark for alignment formed on the screen mask 8 . The print controller C recognizes the position of the mask mark and the position of the substrate mark based on images picked up by the camera unit 13 .

As in 3A 1, a plurality of mounting pads 6a are provided on the substrate 6. As shown in FIG. The print controller C controls the XY stage 9, the θ stage 10 and the substrate elevating mechanism 11 based on the recognizer results regarding the brands. Then, the position and orientation of the substrate 6 with respect to the screen mask 8 are adjusted such that the plurality of openings 8a formed in the screen mask 8 and the plurality of areas 6a on the substrate 6 held by the substrate holder 7 , agree with each other. Subsequently, the pressure controller C raises the substrate holder 7 in such a way that the substrate 6 comes 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 a positioning mechanism 12. The positioning mechanism 12 moves the substrate holder 7 such that alignment of the substrate 6 held by the substrate holder 7 with the screen mask 8 is reached.

A print head 20 is mounted above the screen mask 8 . The print head 20 moves along the Y-axis as indicated by the arrow a3 by a second moving mechanism 15 which will be described later with reference to FIG 6 is described. The print head 20 includes a moving base unit 21 which moves by means of the second moving mechanism 15 in the horizontal plane. On the movement base unit 21, two squeegee holders 22 are arranged side by side along the Y-axis. Each of the squeegee holders 22 holds a squeegee 23 extending along the X-axis at the lower end and moves up and down as indicated by the arrow a4 by a lift mechanism 24 provided in the moving base 21 . The second moving mechanism 15 and the print head 20 are controlled by the print controller C.

Under the screen mask 8 at a negative-side position (front side) in the Y-axis, there is provided a cleaning mechanism 30 which cleans the back surface of the screen mask 8 and removes solder paste Pst remaining in the opening 8a. The cleaning mechanism 30 moves along the Y-axis as indicated by an arrow a5 by a third moving mechanism 16 which will be described later with reference to FIG 6 is described. The third moving mechanism 16 is controlled by the print controller C. The cleaning mechanism 30 includes a wiping head 31. The wiping head 31 extends along the X-axis and moves along the Z-axis as indicated by an arrow a6.

In the cleaning mechanism 30, a platen 33A around which unused cleaning paper 32 is wound and a platen 33B collecting used cleaning paper 32 are respectively attached to the front and rear in the Y-axis between which the wiping head 31 is sandwiched . The cleaning paper 32 pulled out from the platen 33A runs over the upper surface of the wiping head 31 in sliding motion and is wound around the platen 33B. The platen roller 33B is rotated by a roller rotating mechanism 34 controlled by the print controller C. The cleaning mechanism 30 further includes an applicator 35. The applicator 35 is controlled by the pressure controller C, and applies to the cleaning paper 32 a solvent for dissolving the flux contained in the solder paste Pst.

When solder paste Pst remaining on the screen mask 8 is removed, the print controller C cleans the screen mask 8 in a predetermined pattern by a wet cleaning method or a dry cleaning method. In the wet cleaning process, the pressure controller C uses the wiping head 31 to lift the cleaning paper 32 on which the solvent has been applied by the applicator 35 . As a result, the cleaning paper 32 abuts the rear surface of the screen mask 8, and the cleaning mechanism 30 is moved along the Y-axis. In this way, the print controller C wipes off remaining solder paste Pst. In the dry cleaning method, the pressure controller C lifts the cleaning paper 32 on which the solvent is not applied by means of the wiping head 31 so that the cleaning paper 32 abuts the back surface of the screen mask 8 . Then, the cleaning mechanism 32 is moved along the Y-axis to wipe off the remaining solder paste Pst.

With reference to 3A until 3C Next, a printing step (printing process) for printing solder paste Pst on the substrate 6 by the printer M1 will be described. As in 3A 1, the plurality of areas 6a are provided on the substrate 6. As shown in FIG. A resist material 6b, which is an insulator, is coated on a portion of the upper surface of the substrate 6 other than the surfaces 6a. The substrate 6 moves under the screen mask 8 and is held by the substrate holder 7 . During the printing process, the print controller C first controls the in 2 Positioning mechanism 12 shown in such a way that an alignment between the substrate 6 and the screen mask 8 takes place. Then, the print controller C raises the substrate holder 7 as indicated by an arrow b1 so that the substrate 6 is brought into contact with the lower surface of the screen mask 8. FIG.

Subsequently lowers, as in 3B As shown, the print controller C lowers the squeegee 23 to rest on the screen mask 8 and shifts the squeegee 23 along the Y-axis as indicated by an arrow b2. Through this ver The solder paste Pst applied to the screen mask 8 is pushed into the openings 8a and transferred onto the substrate 6 by sliding in the form of a sliding movement. In this transfer step, the print controller C transfers the solder paste Pst onto the substrate 6 according to the predetermined printing condition. The predetermined printing condition includes a pressure (pressure for printing) for pressing the squeegee 23 onto the screen mask 8 and includes a speed for moving the squeegee 23.

Next lowers, as in 3C 1, the print controller C peels off the substrate holder 7 as shown by an arrow b3, and meanwhile the substrate 6 peels off the screen mask 8. In this peeling step, the print controller C separates the substrate 6 from the screen mask 8 according to Figs Separating process conditions for lowering the substrate 6 at the predetermined lowering speed. As a result, solder paste Pst is printed (deposited) on the faces 6a of the substrate 6. FIG. The solder paste Pst contains solder particles S and a flux F, and when the solder paste Pst is printed on the substrate 6, the flux F having some fluidity is smeared on the outer peripheral portion of the solder particles S deposit. As described above, the printer M1 prints the solder paste Pst containing the solder particles S and the flux F onto the substrate 6 through the openings 8a provided in the screen mask 8.

Next, with reference to 4 a structure of the inspection device M2 is described. The inspection device M2 has two transport units 41 as a pair, which move along the X-axis on a base 40. As shown in FIG. The transport units 41 transport a printed substrate (hereinafter referred to as a substrate) 6P picked up by the printing equipment M1 from the upstream side to an inspection position along the X-axis, and when the inspection is completed, the printed substrate 6P is lifted up transported away from the downstream side of the inspection device M2. A substrate holder 42 is provided in the area of the center of the X-axis of the transport units 41 . The substrate holder 42 receives the substrate 6P transported by the transport units 41 and holds the substrate 6P at a predetermined clamp position (inspection position). A gauge 43 for measuring the weight of the substrate 6 is provided in the substrate holder 42 .

An inspection head 44 is mounted above the substrate holder 42 . The inspection head 44 moves in the horizontal plane by a moving mechanism 45 which will be described later with reference to FIG 7 is described. The inspection head 44 includes an inspection camera (hereinafter camera) 46, a first lighting unit 47, a second lighting unit 48 and a height detector 49. The camera 46 is mounted so that an optical axis 46a faces downward, and the camera moves above the The substrate 6 held by the substrate holder 42 such that the solder paste Pst printed on the substrate 6 is photographed.

The first illumination unit 47 is mounted around the camera 46 and illuminates the substrate 6 in an area to be photographed by the camera 46 . Further, the second illuminating unit 48 is arranged around the camera 46 and outside the first illuminating unit 47 when viewed from the camera 46, and illuminates the substrate 6 in an area to be photographed by the camera 46. That is, second illumination light 48a emitted from the second illumination unit 48 is more inclined with respect to the substrate 6 than first illumination light 47a emitted from the first illumination unit 47 .

In the inspection device M<b>2 , the first lighting unit 47 and the second lighting unit 48 are respectively switched or used simultaneously with the aim of having a photograph taken by the camera 46 . Alternatively, the intensity of the first illumination light 47a emitted from the first illumination unit 47 and the intensity of the second illumination light 48a emitted from the second illumination unit 48 are respectively changed with the aim of taking a photograph by the camera 46 . A height detector 49 includes such as a 3D sensor, moves over the substrate 6 held by the substrate holder 42, measures a shape including a position of the solder paste Pst printed on the substrate 6 and a height of the Solder paste Pst while the substrate 6 is being irradiated with measurement light 49a and detects a state of the solder paste Pst printed on the substrate 6 .

Next, with reference to 5A and 5B An example of an image of the substrate 6P captured by the camera 46 of the inspection device M2 will be described, the substrate 6P having solder paste Pst printed on by the printer M1.

5A 12 shows an image 50 obtained when the first illumination unit 47 emits the first illumination light 47a, and 5B Fig. 5 shows an image 51 obtained when the second illumination unit 48 emits the second illumination light 48a, both images being obtained by taking a picture of the same position on the substrate 6 using the camera 46 . In 5A For example, the solder paste Pst is printed in columnar form on the areas 6a formed on the upper surface of the substrate 6 through circular openings 8a formed in the screen mask 8. FIG.

The image 50 taken when the substrate is irradiated with the first illumination light 47a shows deposits of the solder particles S contained in the solder paste Pst in addition to the boundary between the faces 6a and the resist 6b on the substrate 6. In 5B 51 shows an image taken when the substrate is irradiated with the second illumination light 48a, the flux F contained in the solder paste Pst in addition to the boundary between the faces 6a and the resist 6b on the substrate 6 and deposits of solder particles S. The flux F flows out from the deposition areas of the solder particles S printed on the substrate 6. As described above, the state of the flux F on the substrate 6 can be detected by obliquely irradiating the substrate with the second illumination light 48a.

As described above, the camera 46 and at least one lighting unit (first lighting unit 47 and second lighting unit 48) that irradiates the substrate 6 photographed by the camera 46 act as a detector, the solder particles S and the flux F of the solder paste Pst printed on the substrate 6 is detected. The inspection device M2 inspects the state of the solder paste Pst printed on the substrate 6. FIG. That is, this detector is provided in the inspection device M2 included in the screen printing system 1. FIG.

With reference to 6 Next, a construction of a control system of the printer M1 will be described. The printing controller C included in the printing system M1 is connected to the transport units 5, the substrate holder 7, the positioning mechanism 12, the camera unit 13, the first moving mechanism 14, the second moving mechanism 15, the third moving mechanism 16, a touch panel 17, connected to the printhead 20 and the cleaning mechanism 30. The touch panel 17 has a display function of displaying, for example, an operation screen of the printing machine M1 on a liquid crystal panel, and has an input function of inputting commands, various kinds of information and others by operating the displayed operation screen. Note that 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 separately.

The print controller C includes a storage unit 60, a first processor 61, a second processor 62, a plan management unit 63, a third processor 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, for example, a writable random access memory (RAM). The storage unit 60 stores, for each kind of the substrate 6, the printing condition under which the printhead 20 prints the solder paste Pst on the substrate 6, the mask cleaning condition for performing the mask cleaning, and others.

As described above, the printing condition includes the pressure value (pressure at the time of printing) with which the squeegee 23 presses solder paste Pst into the plurality of openings 8a, the moving speed of the squeegee 23 at the time of printing, the separation speed at which the substrate 6 is separated after the printing is detached from the screen mask 8, and others. Furthermore, the mask cleaning condition includes the timing to perform the mask cleaning, the cleaning method (wet cleaning or dry cleaning), and others.

The first processor 61, the second processor 62, the schedule management unit 63, and the third processor 64 include a central processing unit (CPU) or a large scale integrated circuit (LSI). Alternatively, the foregoing units may have special circuitry, and they may be implemented by controlling general-purpose hardware by software read from volatile or non-volatile memory. Two or more of the foregoing units can also be formed as a unit.

The first processor 61 respectively controls the units of the printing machine M1 including the print head 20 based on the printing condition stored in the storage unit 60 and executes the printing operation. The second processor 62 controls the cleaning mechanism 30 and the third moving mechanism 16 according to a command (instruction) from the schedule management unit 63 and performs mask cleaning. Based on the mask cleaning condition stored in the storage unit 60, the plan management unit 63 instructs the second processor 62 to clean the mask Execution according to a predetermined method after the printing process for the predetermined number of substrates 6.

With reference to 11 an example of a normal cleaning process will now be described. The schedule management unit 63 has a counter function, and in normal cleaning, it counts the number of substrates 6 printed after wet cleaning. Then, as shown on the horizontal axis and the upper part of the drawing, after printing four (first to fourth substrates) substrates 6, the plan management unit 63 causes the second processor 62 to perform the dry cleaning. When another four (fifth to eighth substrates) substrates 6 are printed, the plan management unit 63 causes the second processor 62 to perform the dry cleaning again. Then, when another four (ninth to twelfth substrates) substrates 6 are printed, the schedule management unit 63 causes the second processor 62 to perform the wet cleaning and then resets the counter.

if in 6 a defect is detected in the print condition detection process or the flux condition detection process in the inspection device M2, which will be described later, then the third processor 64 changes the print condition stored in the storage unit 60 such that the condition of the solder paste Pst printed on the substrate 6 is improved.

Subsequently, with reference to 7 a structure of a control system of the inspection device M2 is described. An inspection controller 70 included in the inspection device M2 is provided with transport units 41, a substrate holder 42, a measuring instrument 43, a moving mechanism 45, a camera 46, a first lighting unit 47, a second lighting unit 48, a height detector 49 and a touch panel 76 connected. The touch panel 76 has a display function of displaying, for example, an operation screen of the inspection device M2 on a liquid crystal panel, and has an input function of inputting commands, various kinds of information and others by operating the displayed operation screen. Similar to the touch panel 17, the touch panel 76 may be replaced with a display device and an input device provided separately thereto.

The inspection controller 70 includes a first storage unit 71, a second storage unit 72, an inspection processor 73, a flux state determination unit (hereinafter 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 Printing plant M1 via the communication network 2. The first storage unit 71 and the second storage unit 72 are storage devices. The first storage unit 71 stores, for each kind of substrate 6, the inspection condition including the weight of the substrate 6 before printing, the inspection position for the solder paste Pst printed on the substrate 6, the inspection criteria, and others. The second storage unit stores data of the image captured by the camera 46 (hereinafter referred to simply as an image) and stores the inspection result including the states of the detected solder particles S and the flux F. Similar to the storage unit 60, the first storage unit 71 includes and the second storage unit 72 a rewritable RAM, a flash memory, a hard disk and others.

The inspection processor 73 and the determination unit 74 include a CPU or an LSI. Alternatively, the foregoing units may have special circuitry, and may be implemented by controlling general-purpose hardware by software read from volatile or non-volatile memory. The foregoing two units can be constructed as a unit.

The inspection processor 73 controls the camera 46, the first illumination unit 47 and the second illumination unit 48 such that the camera 46 takes a photograph of the substrate 6 while emitting first illumination light 47a or second illumination light 48a. Further, the inspection processor 73 processes the captured image to thereby detect solder particles S and flux F printed on the substrate 6 . The detection result is stored in the second storage unit 72 . That is, the second storage unit 72 stores the detection result obtained by the detector including the camera 46, the first illumination unit 47, and the second illumination unit 48.

Furthermore, the inspection processor 73 controls the measuring instrument 43 so that the weight of the printed substrate 6P held in the substrate holder 42 is measured. The measurement result is stored in the second storage unit 72 .

The inspection processor 73 controls the height detector 49 so that the three-dimensional shape of the solder paste Pst printed on the substrate 6 is measured. Consequently, the Inspection processor 73 Solder particles S and flux F based on the height of the solder paste Pst with respect to the surface 6a, based on the height of the solder paste Pst from the varnish 6b, based on the step between the deposits of the solder particles S and the flux F, and the like. The detection result is stored in the second storage unit 72 . That is, the height detector 49 acts as a detector that detects solder particles S and flux F of the solder paste Pst printed on the substrate 6, respectively.

With reference to 8A until 8D states of the screen mask 8 after the printing process will now be described. 8A 12 shows a state of the screen mask 8 before printing or immediately after wet cleaning, with solder paste Pst being removed from the openings 8a and the lower surface of the screen mask 8. FIG. 8B until 8D 12 schematically show states of the screen mask 8 after the printing process has been repeatedly performed without cleaning the mask. After the printing, residues such as solder particles S and flux F adhere to the openings 8a and the lower surface of the screen mask 8, and the amount of the residues increases by repeating the printing.

With reference to 5A , 5B , 9A , 9B , 10A and 10B Examples of images of substrate 6 taken by camera 46, substrate 6 having solder paste Pst printed thereon, will now be described. 9A , 9B , 10A and 10B are obtained by taking the same position on the substrate 6 as in 5A and 5B is recorded. In 5A and 5B the printing process is carried out by the screen mask 8 immediately after the in 8A performed wet cleaning shown, and the number of repetitions of printing in 10A and 10B is larger than in 9A and 9B . For example, in 9A and 9B the printing process through the screen mask 8 in the in 8C executed state shown, and in 10A and 10B is the printing process through the screen mask 8 in the in 8D state shown. This in 9A shown picture 54 and in 10A The image 54 shown is recorded while the first illumination unit 47 emits first illumination light 47a. This in 9B shown picture 53 and in 10B The image 55 shown is recorded while the second illumination unit 48 emits the second illumination light 47a.

As is apparent from these drawings, as the residues adhered to the screen mask 8 increase, the shape of the deposits of the solder particles S printed on the substrate 6 shrinks, and the solder particles S spread horizontally. Furthermore, the area of the flux S leaking from the solder particles S also increases. The “solder bridge” is caused at a position indicated by a dotted circle c in Figure 54 in 10A is specified. That is, the deposits of the solder particles S printed on the faces 6a disperse and combine with the deposits of adjacent solder particles S. In the picture 55 in 10B the flux F connects two adjacent surfaces 6a.

As described above, as the residues on the screen mask 8 increase, the amount of flux S printed on the substrate 6 increases. Then, by observing the state of the flux F (flux state) printed on the substrate 6, the occurrence of the printing defect such as the solder bridge, which develops as the printing is continued, can be predicted.

In 7 The determination unit 74 determines from images 51, 53 and 55, which are recorded by the camera 46 while the substrate 6 is illuminated by the second illumination light 48a, whether the state of the flux S on the substrate 6 is good or defective. For example, the determination unit 74 calculates the area (the amount of flux) of the printed flux F and determines that the condition of the flux F is good when the area is within a criterion (threshold value). If the value exceeds the criterion, then the condition of the flux F is determined to be defective. Note that the determination unit 74 can determine the quality of the state of the flux F from the shape of the flux F in addition to the area of the flux F printed.

With reference to 11 an example of the quality determination of the state of the flux F by the determination unit 74 will now be described. 11 13 is a graph showing the amount of flux of flux F detected from images 51, 53, and 55 in the order in which substrates 6 are printed. The white circles connected by a solid line d schematically represent the normal course of the amount of flux on the substrate 6. That is, the amount of flux gradually increases from wet cleaning to the next wet cleaning (first to twelfth substrates). increases, the amount of flux decreases slightly after dry cleaning (fifth to ninth substrate), and the amount of flux immediately decreases after wet cleaning (thirteenth substrate). As described above, in the normal state, the wet cleaning is performed before the amount of flux exceeds the threshold.

Black circles connected by a chain line e indicate that the residue of solder paste Pst remaining on the screen mask 8 after the printing process increases more rapidly than in the normal state, and the amount of flux exceeds the threshold in the seventh substrate 6 In this case, the determination unit 74 determines that the flux state of the seventh substrate 6 is defective.

Outline triangles connected by a dotted line f indicate that a large amount of residues of the solder paste Pst adheres to the screen mask 8 after the printing of the sixth substrate, and the amount of flux of the seventh substrate 6 increases rapidly, although the Amount of flux is within the threshold. In this case, based on the amount of flux of the sixth substrate and the amount of flux of the seventh substrate, the determination unit 74 predicts that the amount of flux will exceed the threshold value after the eighth substrate and the flux state will become abnormal. That is, the determination unit 74 determines the state of the flux F based on the previous detection result (sixth substrate) stored in the storage unit 72 and based on the current detection result (seventh substrate) detected by the detector.

In the 7 The determination unit 74 shown determines the state of the flux F from the image recorded by the camera 46 . Furthermore, the determination unit 74 can determine the state of the flux F from the amount of flux of the flux F detected by the height detector 49 . Further, the determination unit 74 can calculate the weight of the printed solder paste Pst from the weight of the substrate 6 before printing stored in the storage unit 71 and the weight of the substrate 6 after printing measured by the gauge 43 . Furthermore, the determination unit 74 can 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 and recorded by the camera 46 from the weight of the printed solder paste Pst.

That is, the detection unit 74 can detect the state of the flux F from the weight of the substrate 6 before and after the solder paste Pst is printed. That is, the measuring instrument 43 and the camera 46 act as a detector that detects solder particles S and 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 defective from the detection result obtained from the detector (camera 46, first illumination unit 47, second illumination unit 48, measuring instrument 43 and height detector 49). The result of the determination is transmitted to the management computer 3 and the printing system M1.

After receiving the result of the determination that the state of the flux F is defective (for example, the amount of flux exceeds the threshold value) from the determination unit 74 of the inspection device M2, the in 6 illustrated plan management unit 63 the second processor 62 to perform the wet cleaning, and then resets the counter. Note that when printing has already started on the subsequent substrate 6, the wet cleaning is performed after the substrate 6 being processed is printed.

In particular, an example of the 11 shown black circles described. When the determination unit 74 determines that the state of the flux F on the seventh substrate 6 is abnormal, the determination result indicating that the state of the flux F is abnormal is transmitted to the printing equipment M1. In the printing system M1, the schedule management unit 63 instructs the second processor 62 to perform the wet cleaning and resets the counter. Then, in the printer M<b>1 , the wet cleaning is performed before the printing process is performed on the eighth substrate 6 . When the wet cleaning is performed, solder particles S and flux F adhering to the screen mask 8 are removed, and the condition of the solder paste printed on the substrate 6 is improved.

That is, when the determination unit 74 determines that the state of the flux F is abnormal, the printer M<b>1 performs a process of changing the state of the flux F of the solder paste Pst to be printed on the substrate 6 . In this case, the process of changing the state of the flux F in the printing machine M1 is cleaning (wet cleaning) the screen mask 8 by means of the cleaning mechanism 30 provided in the printing machine M1. Thereby, it is possible to prevent in advance the state of printing the solder particles S from becoming defective.

If the determination result indicating that the state of the flux F is defective is transmitted from the determination unit 74, then the in 6 illustrated third processor 64 change the stored in the memory unit 60 printing condition. That is, the operation of changing the state of the flux F of the solder paste Pst to be printed on the substrate 6, which is performed after the determination unit 74 determines that the state of the flux F is abnormal is, in this case, may be the process of changing (updating) the printing condition.

That is, the change is made to the condition under which the printing machine M1 contacts the substrate 6 with the screen mask 8 and transfers the solder paste Pst to the substrate 6, and is made to the condition under which the printing machine M1 transfers the substrate 6 separates from the screen mask 8 after the transfer of the solder paste Pst onto the substrate 6, and the like. More specifically, the printing pressure, the moving speed or the separating speed of the squeegee 23, and the like are changed. This enables the state of printing for the solder particles S to be prevented from becoming defective in advance. The printing condition does not necessarily have to be changed every time a determination result is obtained that the flux state is abnormal. For example, the printing condition may be changed when the occurrence of defects occurs twice in succession during normal cleaning, or when the occurrence of defects exceeds a predetermined number of times.

In the foregoing exemplary embodiment, an example is described in which the determination unit 74 is provided in the inspection facility M2, and the plan management unit 63 and the third processor 64 are provided in the printing facility M1, but the screen printing system 1 is not limited to this configuration. For example, the management computer 3 can contain the determination unit 74 , the plan management unit 63 and the third processor 64 . Further, the printing equipment M1 may include the measuring instrument 43 that measures the weight of the substrate 6 before and after the printing process.

With reference to 12 and 13 a screen printing method in the screen printing system 1 will be described next. In 12 First, the substrate 6 is introduced by the transport units 5 into the printing system M1 of the screen printing system 1 (ST1). Then, the substrate holder 7 holds the substrate 6, and the positioning mechanism 12 aligns the substrate 6 with the screen mask 8 (ST2) and brings the substrate 6 into contact with the screen mask 8 (ST3). Then, the printhead 20 transfers solder paste Pst through the mask screen 8 onto the substrate 6 in contact with the mask screen (ST4), and the substrate lifting mechanism 11 peels the substrate 6 from the mask screen 8 (ST5).

Consequently, solder paste Pst is printed on the substrate 6, and the printed substrate 6P is thus manufactured. That is, ST2 to ST5 are a printing step (ST30) for printing solder paste Pst on the substrate 6. Then, the printed substrate 6P is transferred to the inspection device M2 (ST6). Subsequently, at least one lighting unit (first lighting unit 47 and second lighting unit 48) illuminates the substrate 6P (ST7), and the camera 46 captures an image of the solder paste Pst printed on the substrate 6 (ST8). Subsequently, the inspection processor 73 recognizes solder particles S and flux F of the solder paste Pst printed on the substrate 6 by performing image recognition on the captured image (ST9).

Subsequently, the gauge 43 measures the weight of the substrate 6P after solder paste Pst is printed thereon (ST10). As described above, ST7 to ST10 are a detection step (ST31) for detecting solder particles S and flux F of the solder paste Pst printed on the substrate 6. FIG. Then, the detection result in the detection step (ST31) is stored in the second storage unit 72 (ST11).

Next determined in 13 from the image captured in ST8, the inspection processor 73 whether the state of solder particles S is good or defective (ST12). If the print state is erroneous (erroneous in ST12), then that fact is transmitted to the downstream component mounter. Further, in the printing equipment M1, printing error processing such as cleaning (dry cleaning) of the screen mask 8 and changing of the printing condition are executed (ST13). If the print condition is good (good in ST12) and the print error processing (ST13) is executed due to the print error condition, then the substrate 6P is discharged from the screen printing system 1 (ST14).

When the processing of the printed substrate 6P is not finished (No in ST15), then the determination unit 74 determines from the detection result in step (ST31) whether the state of the flux F on the printed substrate 6P that is already inspected is the predetermined one Exceeds criterion or not, i.e., whether the flux condition is good or defective (ST16). That is, the determination unit 74 can determine the state of the flux F based on the stored previous detection result and based on the current detection result obtained in the detection step (ST31). Specifically, the determination unit 74 determines the state of the flux F from the image captured in ST8. Alternatively, the determination unit 74 may determine the state of the flux F from the weight of the substrate 6 before printing and the weight of the substrate 6 after printing as measured in ST10.

If it is determined in ST16 that the state of the flux F is abnormal, then the schedule management unit 63 causes the second processor 62 to perform the wet cleaning (ST17) and resets the counter to zero (ST18). Subsequently, the third processor 64 changes the printing condition stored in the storage unit (ST19). Therefore, the condition for transferring the solder paste Pst onto the substrate 6 in ST4 and/or the condition for separating the substrate 6 from the screen mask 8 in ST5 are changed.

As described above, ST17 to ST19 constitute a changing step (ST32) for executing the process of changing the state of the flux F of the solder paste Pst to be printed on the substrate 6 when it is determined in ST16 that the state of the flux F is faulty. This can prevent a printing error from occurring in advance.

If the state of the flux F is determined to be good in ST16, then the schedule management unit 63 causes a normal cleaning operation to be carried out according to the number of the counter (ST20). After the changing step (ST32) or after the normal cleaning process (ST20), the process flow returns to ST1 and then the next substrate 6 is fed.

As described above, the screen printing system 1 includes the printing equipment M1. The screen printing system 1 includes a detector that detects solder particles S and flux F of the solder paste Pst printed on the substrate 6, and includes the determination unit 74 that determines from the detection result obtained by the detector whether the state of the flux F is good or not is faulty. That is, when the determination unit 74 determines that the state of the flux F is abnormal, the printing equipment M<b>1 performs the process of changing the state of the flux F of the solder paste Pst to be printed on the substrate 6 . Thereby, a defect in printing can be prevented in advance. Note that the detector may only need to detect the condition of the flux F of the solder paste Pst. Therefore, the detector does not have to have the camera 46, the first lighting unit 47, the second lighting unit 48, the measuring instrument 43 and the height detector 49, respectively. For example, if the detector is able to sufficiently detect the state of the flux F with the camera 46 and the first lighting unit 47 and/or the second lighting unit 48, then the measuring instrument 43 and the height detector 49 can be omitted.

In the foregoing exemplary embodiment, an example is described in which the quality of the state of the flux F is fed back to trigger execution of cleaning of the screen mask 8 and change of the printing condition in the screen printing. However, the quality determination for the condition of the flux F is not limited to the previous application. For example, if a solder area is formed on the surface 6a by a method other than screen printing, then the quality evaluation can be used to determine the state of formation of the solder area. Further, in the method, based on the determination result, a process of changing the state of the flux of the solder paste may be performed.

Industrial Applicability

The solder paste printing system and the solder paste printing method of the present disclosure bring about the effect of being able to prevent a defect in printing in advance, and are useful in the field of mounting an electronic component on a substrate.

Reference List

1

screen printing system

2

communication network

3

management calculator

4, 40

base frame

5, 41

transport unit

6

substrate

6a

surface or mounting surface

6b

paint

6p

printed substrate (substrate)

7

substrate holder

8th

screen mask

8a

opening

8w

frame element

9

XY table

10

θ table

11

substrate lifting mechanism

12

positioning mechanism

13

camera unit

14

first movement mechanism

15

second movement mechanism

16

third movement mechanism

17, 76

touch panel

20

printhead

21

movement base unit

22

squeegee holder

23

squeegee

24

lifting mechanism

30

cleaning mechanism

31

mop head

32

cleaning paper

33A, 33B

paper roll

35

applicator

42

substrate holder

43

measuring instrument

44

inspection head

45

movement mechanism

46

inspection camera (camera)

46a

optical axis

47

first lighting unit

47a

first illumination light

48

second lighting unit

48a

second illumination light

49

height detector

49a

measuring light

50, 51, 52, 53, 54, 55

picture

60

storage unit

61

first processor

62

second processor

63

Plan Management Unit

64

third processor

65, 75

communication unit

70

inspection control

71

first storage unit

72

second storage unit

73

inspection processor

74

Flux condition determination unit (determination unit)

C

pressure control

f

flux

M1

printing system

M2

Printed Solder Inspection Facility (Inspection Facility)

hush

solder paste

S

solder particles

Claims (17)

A solder paste printing system, comprising: a printing system that prints solder paste containing solder particles and flux onto a substrate; a detector that detects the solder particles and the flux of the solder paste printed on the substrate; and a flux state determination unit that determines whether a state of the flux is good or defective based on a detection result obtained by the detector, whereby when the flux state determination unit determines that the state of the flux is abnormal, the printing equipment performs an operation of changing the state of the flux of the solder paste before the solder paste is printed on an unprinted substrate. The solder paste printing system claim 1 further comprising a storage unit that stores the detection result obtained from the detector, wherein the flux state determination unit determines the state of the flux based on a previous detection result stored in the storage unit and based on a current detection result detected by the detector. The solder paste printing system claim 1 or 2 , wherein the detector comprises: a camera taking a photo of the onto the substrate printed solder paste; and at least one illumination unit that irradiates the substrate with light, and the flux state determination unit determines the state of the flux based on an image captured by the camera. The solder paste printing system claim 3 wherein the flux state determination unit determines that the state of the flux is defective based on a determination result that an area of the flux printed on the substrate in the image exceeds a criterion. The solder paste printing system according to one of the Claims 1 until 4 , wherein the detector comprises a measuring instrument that measures a weight before printing the substrate before printing the solder paste and a weight after printing the substrate after printing the solder paste, the weight after printing being a total weight of the substrate and the solder paste , and the flux state determination unit determines the state of the flux based on the weight before printing and the weight after printing. The solder paste printing system claim 5 wherein the flux state determination unit determines that the state of the flux is abnormal based on a determination result that an amount of the flux obtained by calculating a difference between the weight before printing and the weight after printing exceeds a threshold. The solder paste printing system according to one of the claims 3 until 6 further comprising a printed solder inspecting device which inspects a state of the solder paste printed on the substrate, wherein the detector is provided in the printed solder inspecting device. The solder paste printing system according to one of the Claims 1 until 7 wherein the printing system includes an apertured screen mask used to print the solder paste onto the substrate and a cleaning mechanism configured to clean the screen mask, and the printing system performs a flux state changing operation , the operation being cleaning of the screen mask by the cleaning mechanism. The solder paste printing system according to one of the Claims 1 until 8th wherein the printing system includes the apertured screen mask used to print the solder paste onto the substrate, and the printing system performs the process of changing the state of the flux, the process changing a condition for transferring the solder paste of the screen mask onto the unprinted substrate by causing the unprinted substrate to be brought into contact with the screen mask by the printing equipment. The solder paste printing system according to one of the Claims 1 until 9 wherein the printing equipment includes the apertured screen mask used to print the solder paste on the substrate, and the printing equipment performs the process of changing the state of the flux, the process changing a condition for peeling off the unprinted substrate from the screen mask after the solder paste has been transferred to the unprinted substrate by the printing equipment. A solder paste printing process that includes: printing solder paste containing solder particles and flux onto a substrate; obtaining a detection result by detecting the solder particles and the flux of the solder paste printed on the substrate; determining whether a condition of the flux is good or bad based on the detection result, and if the state of the flux is determined to be defective, performing a process of changing the state of the flux of the solder paste before the solder paste is printed on an unprinted substrate. The solder paste printing process claim 11 , further comprising: storing the detection result; and determining that the condition of the flux is good or bad based on a previous detection result that is stored and a current detection result that is detected. The solder paste printing process claim 11 or 12 , wherein the method further comprises, when obtaining the detection result: irradiating the substrate with light by at least one illumination unit; capturing a photo of the solder paste printed on the substrate by a camera; and determining the condition of the flux based on an image that is captured. The solder paste printing method according to one of the Claims 11 until 13 , wherein the method, when obtaining the detection result, further comprises: measuring a weight before printing the substrate before printing the solder paste and a weight after printing the substrate after printing the solder paste, the weight after printing being a total weight of the substrate and the solder paste is; and determining the condition of the flux based on the weight before printing and the weight after printing. The solder paste printing method according to one of the Claims 11 until 14 , the method further comprising: printing the solder paste onto the substrate through a screen mask provided with an opening, wherein the state of the flux is changed by a process for cleaning the screen mask. The solder paste printing method according to one of the Claims 11 until 15 wherein the method of printing the solder paste onto the substrate further comprises: transferring the solder paste through the screen mask onto the substrate which is brought into contact with the screen mask provided with the opening, the state of the flux being changed by a condition changing operation Transfer of the solder paste to the non-printed substrate is changed. The solder paste printing method according to one of the Claims 11 until 16 wherein the method of printing the solder paste onto the substrate further comprises: transferring the solder paste through the screen mask onto the substrate which is brought into contact with the apertured screen mask; and peeling off the substrate from the screen mask after transferring the solder paste onto the substrate, wherein the state of the flux is changed by an operation for changing a condition for peeling the non-printed substrate from the screen mask.

Images