JP2009177015A - Solder ball printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder ball printer capable of efficiently and securely charging and printing solder balls to form bumps. <P>SOLUTION: A solder ball printing system includes a flux printing unit 101 which prints flux on electrode pads of a substrate, a solder ball charging-printing unit 103 which supplies solder balls onto the electrode with the printed flux, and an inspection-repair unit 104 which inspects the state of the substrate where the solder balls are printed and makes a repair according to a defective state is provided. A flux inspection-repair unit 102, which inspects the state of the substrate with the printed flux and makes a repair according to a defective state, is provided between the flux printing unit 101 and the solder ball charging-printing unit 103; and the solder ball charging-printing unit 103 includes a screen 20 which supplies the solder balls and a printing means having a slit body for charging the solder balls in the screen 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a screen printing apparatus, and more particularly to a solder ball printing apparatus for printing a solder ball on a substrate surface.

  In ball bump formation (diameter 50 to 100 μm) with a pitch of 100 to 180 μm, there is a printing method in which a solder ball is formed by reflowing cream solder after printing using a known high-precision screen printing apparatus. As an example of the screen printing apparatus, a substrate carry-in conveyor, a substrate carry-out conveyor, a table unit provided with a lifting mechanism, a mask having a transfer pattern as an opening, a squeegee, a squeegee lifting mechanism, and a squeegee head equipped with a horizontal movement mechanism, A control device for controlling these mechanisms is provided.

  After the substrate is carried into the apparatus from the carry-in conveyor unit, the substrate is temporarily positioned and fixed to the printing table unit. Thereafter, both the mark on the substrate and the mask (screen) having an opening corresponding to the circuit pattern are recognized by the camera. Then, correct the position of both displacements, align the substrate with the screen, lift the print table so that the substrate contacts the screen, and then apply cream solder to the opening of the screen while making the screen contact the substrate with a squeegee. The paste is transferred onto the substrate by lowering the table and separating the screen from the screen (separating the plate), and then printing is performed by unloading the substrate from the apparatus.

  Also known is a ball transfer method in which solder balls are formed by transferring solder balls into jigs that have been drilled with high precision and finely aligned, transferred to a substrate directly at a predetermined pitch, and reflowed after placement. Yes.

  Further, according to Patent Document 1, there is a method of filling a predetermined opening with solder balls by swinging or vibrating the mask, or a method of heating after filling by translational movement of a brush or the like. Further, according to Patent Document 2, there is a method in which a solder ball is placed on a tray and adsorbed by a tube to be refilled into an electrode pad.

JP 2000-49183 A JP 2003-309139 A

  The printing method using cream solder has the advantage that the equipment cost is low and a large number of bumps can be formed at once, so that the throughput is high and the manufacturing cost is kept low. However, in the printing method, it is difficult to ensure the uniformity of the transfer volume, and there is a problem that the solder bump after reflow is pressed by the fluttering process to smooth the height, and the number of processes is large and the equipment cost is high. . In addition, when the finer process progresses to a pitch of 100 to 150 μm or the like as the density of the device increases, there is a point that the printing yield is poor and the productivity is not good.

  On the other hand, with the solder ball transfer method, it is possible to form bumps with a stable height by ensuring the classification accuracy of the solder balls. However, since the solder balls are packed together by a robot using a high-precision solder ball adsorption jig, fine solder balls are used. There are problems such as an increase in tact in the case of an increase in cost and an increase in bump formation cost due to an increase in jig / equipment prices.

  Further, in the method of swinging or vibrating the screen according to Patent Document 1 and filling a predetermined opening with a solder ball, an adhesion phenomenon due to van Desworth force between particles or an adsorption phenomenon due to static electricity as the solder ball particle diameter decreases. Occurs and the mask opening cannot be filled. Similarly, there is a similar problem in filling by squeegee or brush translation.

  In the method of Patent Document 2, even if repair is possible, the possibility that the amount of residual flux is small is extremely high. If the solder wettability is poor during batch reflow, the electrode may be melted even if the solder ball melts. There is a risk that poor wetting may occur due to incomplete soldering to the pad portion.

  In order to solve the above problems, the object of the present invention is to inspect and repair the state of the flux after the flux printing, so that a large amount of bumps can be formed in a batch as in the printing method, and soldering is performed. A solder ball filling printing device that can form bumps with a stable height, like the ball transfer method, can form bumps with high productivity and high productivity that enable efficient printing and filling at low cost. Is to provide.

  In order to achieve the above object, the present invention provides a flux printing unit for printing a flux on an electrode pad of a substrate, a solder ball filling / printing unit for supplying a solder ball on the electrode on which the flux is printed, and a solder. In the solder ball printing apparatus comprising an inspection / repair unit that inspects the state of the substrate on which the balls are printed and repairs depending on the defective state, between the flux printing unit and the solder ball filling / printing unit, A flux inspection / repair unit is provided for inspecting the state of the printed substrate and repairing it according to a defective state. The solder ball filling / printing unit includes a screen for supplying solder balls to the substrate, and a solder for the screen. A printing means having a slit-like body filled with a ball is provided.

  The solder ball filling / printing unit includes a magnetic printing table on which a substrate is placed, and the metal screen having an opening that contacts the substrate and supplies solder balls onto the electrodes of the substrate. A printing means having the slit-like metal body disposed above the screen and filled with solder balls in the opening of the screen, the magnetic attraction force of the printing table and the screen, the screen and the slit It was set to be larger than the magnetic attractive force of the body.

The printing table has a neodymium magnet, the screen is made of nickel, and the slit body of the printing means is made of SUS304.
The magnetic attraction force between the printing table and the screen was set to 10 to 100 gf / cm ² , and the magnetic attraction force between the screen and the slit-like body was set to 0.1 to 10 gf / cm ² .

  The printing table is provided with neodymium magnets having a surface magnetic flux density of 500 to 2000G.

  According to the present invention, it is possible to improve productivity by processing a flux printing defect, which is a major cause of a solder ball filling defect, at an early stage in the leading process. In addition, according to the present invention, it is possible to improve the solder ball filling efficiency, shorten the tact time, and perform solder ball filling / printing with a high filling rate, thereby improving productivity. Furthermore, since the operation efficiency of each device from flux printing to solder ball filling to inspection / repair can be improved and tact time can be shortened, solder bump height accuracy is good, and a large amount of stable solder bumps can be made at low cost in a batch. It is possible to form with. In addition, the apparatus has a simple configuration, and the equipment cost can be kept low.

  Hereinafter, preferred embodiments of a printing apparatus and a bump forming method of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a printing process in the flux printing unit and the solder ball filling / printing unit. FIG. 1A shows a flux printing process, and FIG. 1B shows a solder ball filling / printing situation.

  In FIG. 1A, the flux is placed on the flux printing screen 20 provided with openings according to the position and shape of the electrode pads 22 provided in advance on the substrate 21, and the squeegee 3 is moved to move the substrate. A predetermined amount of flux 23 is printed on the 21 electrode pads 22.

  In this embodiment, the screen 20 is a screen for flux printing, and a metal screen manufactured by an additive method is used so as to ensure high-precision pattern position accuracy. As the squeegee 3, either a square squeegee, a sword squeegee or a flat squeegee is used. A screen gap, a printing pressure, and a squeegee speed corresponding to the viscosity and thixotropy of the flux 23 are set and a printing operation is performed. If the printed amount of the flux 23 is too small, the solder ball cannot be attached onto the electrode pad 22 when the solder ball 24 is filled. Further, during reflow, which is a post-process after solder ball printing, it becomes a factor of solder wettability, a solder bump having a beautiful shape cannot be formed, and it becomes a factor of poor solder bump height and insufficient solder connection strength.

  On the other hand, if the amount of the flux 23 is too large, the flux 23 adheres to an opening 20d or the like provided in a screen 20b to be described later for supplying the solder ball 24 onto the electrode pad 22 during filling and printing of the solder ball. There is. When the flux 23 adheres to the screen opening, the solder ball 24 adheres to the opening 20d of the screen and cannot be transferred onto the electrode pad 22. Thus, flux printing is a process having the most important factor in solder ball filling quality.

  Next, as shown in FIG. 1B, in the main part of the solder ball filling / printing unit provided with the filling unit 60 (printing means) (see FIG. 7), the electrode pad of the substrate 21 on which the flux 23 is printed. A solder ball 24 is filled and printed on the surface 22. In order to supply one solder ball 24 to each electrode pad 22, the screen 20 b has an opening 20 d and is supplied in a state where the opening 20 d is aligned on the electrode pad 22. Therefore, a metal screen manufactured by the additive method is used so as to ensure high-precision pattern position accuracy.

  The printing table 10 (magnet stage) on which the substrate 21 is placed is placed so that the gap between the substrate 21 and the screen 20b becomes almost zero so that the solder ball 24 does not sink between the substrate 21 and the screen 20b to cause an excess ball defect. A neodymium magnet is used, and the solder ball filling screen 20b is made of nickel as a magnetic material so that the magnetic force from the printing table 10 is attracted.

  Further, when the printed substrate 21 is in close contact with the back surface of the screen 20b (the side in contact with the substrate 21), a minute nickel-made particle is prevented so that bleeding of the flux 23 does not adhere to the periphery of the screen opening 20d. A plurality of support columns (post structures) 20a are formed integrally with the screen 20b. Thereby, the escape part of the blur of the flux 23 is comprised. Even if this relief portion is configured, the gap between the back surface of the substrate 21 and the screen 20b is extremely small compared to the diameter of the solder ball due to the magnetic attraction force by the printing table 10, so that the solder ball does not get in close proximity. It is a thing.

  In addition, positioning marks (not shown) are provided at four corners of the substrate 21 in order to supply the solder balls 24 to the electrode pads 22 at predetermined positions with high accuracy. Corresponding to the positioning marks provided on the substrate 21 side, positioning marks are also provided on the screen 20b side. These positioning marks are visually recognized by the CCD camera 15 (see FIG. 4), and alignment is performed with high accuracy so that the positioning mark position provided on the screen 20b side matches the positioning mark position on the substrate 21 side. To do. In this embodiment, the alignment is performed by moving the printing table 10 on which the substrate 21 is mounted in the horizontal direction.

  When the alignment is completed, the distance between the substrate 21 and the screen 20b is reduced, the screen 20b is brought into contact with the substrate 21, the filling unit (printing means) 60 is operated, and the solder ball 24 is filled in the opening 20d of the screen 20b. From here, it is supplied to the electrode pads 22 on the surface of the substrate 21 on which the flux 23 is printed. A slit-like body 63 is provided on the lower side of the filling unit 60 for supplying solder balls (see FIG. 7), and the solder ball 24 is pushed and rolled by rotating and advancing the filling unit 60 to rotate and vibrate. To fill the opening 20d of the screen.

  FIG. 2 is a process explanatory diagram of an embodiment of a solder ball printing apparatus. The apparatus shown in this figure is an apparatus in which a flux printing unit 101, a flux inspection / repair unit 102, a solder ball filling / printing unit 103, and a ball mounting inspection / repair unit 104 are integrated. However, each of the parts may be configured as a single device. In addition, a configuration in which the function of flux inspection / repair is combined with the ball mounting inspection / repair unit is also possible. In this apparatus, first, a flux 23 is printed on each electrode pad 22 on the substrate 21 by a flux printing unit (screen printing method) 101. After that, the electrode pad is passed through the screen 20b at the solder ball filling / printing unit 103 via the transfer conveyor (from the slack printing unit side is a carry-out conveyor and when viewed from the solder ball filling / printing unit is a substrate carry-in conveyor). A solder ball 24 is supplied to 22.

  In addition, the part which is largely different between the flux printing unit 101 and the solder ball filling / printing unit 103 is a print head unit, the flux printing unit 101 has a squeegee structure, and the solder ball filling / printing unit 103 is filled for supplying solder balls. The unit 60 is configured. The inspection / repair units 102 and 104 have a dispenser type suction / supply head structure. Further, since it is not necessary to use a screen in the inspection / repair section, there is no plate frame holder for attaching the screen.

  FIG. 3 shows a flowchart of bump formation in the present embodiment. After carrying in the substrate (STEP 1), a predetermined amount of flux is printed on the electrode pad 22 (STEP 2). Next, the electrode pad surface state after flux printing is inspected (STEP 3). In the case of NG (defective) by inspection, the flux is re-supplied to the NG part to be repaired, and NG information is fed back to the flux printing part 101, and the screen cleaning device 45 automatically performs screen cleaning (STEP 4). ).

  It is also possible for the substrate that has become NG to wait on the conveyor in the subsequent process together with the NG signal so as not to carry out the processes after ball printing and to discharge it out of the line. By using an inline NG substrate stocker or the like, the magazine may be discharged in a batch. The NG substrate can be used again for flux printing after being washed in an off-line process.

  Next, solder ball filling and printing are performed (STEP 5). After the solder ball filling and printing, the solder ball filling state from above the screen into the screen opening is inspected before releasing the plate (STEP 6). As a result of the inspection, if there is an insufficiently filled portion, the solder ball filling / printing operation is executed again before releasing the plate (STEP 7). Thereby, the solder ball filling rate can be improved.

  When it becomes OK in STEP6, the plate separation is performed (STEP8). Next, the filling state is inspected by the inspection / repair device 104 after filling the solder balls (STEP 9). In the case of the filling status inspection NG, the solder balls are supplied again to the electrode pad portion at the NG point after supplying the flux (STEP 10). In the case of OK in the filling state inspection, the solder balls are remelted by a reflow device (not shown) to complete the solder bumps.

  FIG. 4 shows a schematic configuration of a screen printing apparatus (mainly a flux printing unit) in the present invention. FIG. 4A shows a configuration viewed from the front of the screen printing apparatus, and FIG. 4B shows a system configuration diagram. Further, FIGS. 5A and 5B are diagrams for explaining the operation of the screen printing apparatus.

  The main body frame 1 is provided with a plate frame receiver (not shown), and a mask with a screen 20 having a printing pattern as an opening is attached to the plate frame 20c (see FIG. 6) is set on the plate frame receiver. It is configured. In this figure, the print head 2 provided with the squeegee 3 is disposed above the screen 20.

  In the case of the flux printing unit 101, a urethane squeegee 3 is attached to the print head 2. In the case of the solder ball filling / printing unit 103, a filling unit (printing means) 60 constituted by a slit-like body 63 or the like is attached to the print head 2 in place of the squeegee 3. The print head 2 is configured to be movable in the horizontal direction by the print head moving mechanism 6 and up and down by the print head lifting mechanism 4. By replacing the squeegee 3 with the filling unit 60, the filling unit 60 can be moved in the vertical direction by the print head lifting mechanism 4.

  Below the screen 20, a printing table 10 is provided so as to place and hold a substrate 21 that is a printing target so as to face the screen 20. The printing table 10 receives the substrate 21 from the carry-in conveyor 25 and moves the substrate 21 in the horizontal direction (XYθ direction) to align it with the screen 20, and brings the substrate 21 close to the screen 20 surface. Or a table raising / lowering mechanism 12 for contacting.

  A substrate receiving conveyor 26 is provided on the upper surface of the printing table 10, and the substrate 21 carried by the substrate carrying conveyor 25 is received on the printing table 10, and when printing is completed, the substrate 21 is discharged to the substrate carrying conveyor 27.

  The screen printing apparatus has a function of automatically aligning the screen 20 and the substrate 21. That is, the CCD camera 15 images the alignment marks provided on each of the screen 20 and the substrate 21 and performs image processing to obtain a positional shift amount, and the XYθ table 11 is corrected so as to correct the shift amount. It is driven and aligned.

  Note that the printing control unit 36 including the plate separation control unit 39, the drive control unit of each unit, and the printing press control unit 30 provided with the image input unit 37 that processes the image signal from the CCD camera 15 are included in the main frame of the printing press. A data input unit 50 provided inside for rewriting control data, changing printing conditions, and the like, and a display unit 40 for monitoring the printing status and captured recognition marks are provided outside the printing press. It is arranged.

  The printing press control unit 30 has a printing control unit 36 for controlling the filling unit 60, and it is easy to select an appropriate filling / printing mode depending on the pitch of the bump to be produced, the difference in the solder ball particle diameter, and the type of the metal mask to be used. Select setting is possible.

  In addition, a correlation value calculation unit 31 that calculates a correlation value according to an input image, a shape estimation unit 32 that calculates a shape based on the captured image and data from the dictionary 38, a position coordinate calculation unit 33 that calculates a position coordinate, dimensions A calculation unit 34 is provided, and based on position recognition marks provided on the substrate 21 and the screen 20 from data captured by the CCD camera 15, a positional deviation amount is obtained, and an XYθ table is determined based on a command from the XYθ table control unit. 11 is driven to perform alignment.

  Next, taking the solder ball filling / printing section as an example, the operation of the printing apparatus will be described. The substrate 21 on which the solder bumps are formed is supplied to the substrate receiving conveyor 26 by the substrate carry-in conveyor 25. When the substrate 21 is transported to the position of the printing table 10, the substrate 21 is transferred from the substrate receiving conveyor 26 onto the printing table 10 by raising the printing table 10. The substrate 21 delivered to the printing table 10 is fixed at a predetermined position on the printing table 10. After fixing the substrate 21, the CCD camera 15 is moved to a substrate mark position registered and set in advance. The situation is shown in FIG.

  Subsequently, the CCD camera 15 images a position recognition mark (not shown) provided on the substrate 21 and the screen 20 and transfers it to the printing press control unit 30. The image input unit 37 in the printing press control unit obtains the amount of positional deviation between the screen 20 and the substrate 21 from the image data, and the printing press control unit 30 operates the XYθ table control unit 35 that moves the printing table 10 based on the result. Thus, the position of the substrate 21 relative to the screen 20 is corrected and aligned.

  The situation after the alignment operation is completed is shown in FIG. First, a predetermined amount of retraction is performed until the CCD camera 15 does not interfere with the print table 10. After the CCD camera 15 is retracted, the printing table 10 is raised and the substrate 21 and the mask 20 are brought into contact with each other. In this state, the print head elevating mechanism 4 is operated to bring the squeegee (in the figure, the squeegee 3 is shown, but in the solder ball filling step, it becomes the slit-like body 63 at the tip of the filling unit 60) into contact with the screen surface. Next, an opening provided on the screen surface from the opening of the slit-like body 63 is moved horizontally by rotating and driving the motor 2g for driving the print head while vibrating and swinging the slit-like body 63. The solder balls 24 are filled in the electrode pads 22 of the substrate 21 via

  The print head 2 moves up after a certain distance stroke in the horizontal direction. Then, the printing table 10 is lowered, the screen 20 and the substrate 21 are separated, and the solder balls 24 filled in the openings of the screen 20 are transferred to the substrate 21. And the board | substrate 21 with which the solder ball 24 was printed is sent to the following process through the board | substrate carrying-out conveyor 27. FIG.

  As described above, the substrate 21 and the screen 20 are provided with two or more recognition alignment marks at the same relatively position. Each of these marks is recognized by the special CCD camera 15 having two vertical fields of view, the mark on the screen 20 is recognized from below, the mark on the substrate 21 is recognized from above, and all the marks provided at predetermined positions are all recognized. The position coordinates are read, the amount of displacement of the substrate 21 with respect to the screen 20 is calculated and corrected, and the substrate 21 is aligned with the screen 20.

  FIG. 6 shows the opening state of the screen after printing the flux. 6A shows the state of the entire screen, FIG. 6B shows the state of the opening provided with one electrode group, and FIG. 6C shows the state of the opening after the flux 23 is printed. Show. FIG. 6C shows the opening state of the normal screen 20 after the flux 23 is printed. The flux 23 is sufficiently filled in the opening 20k of the screen 20 by setting the appropriate screen gap (the distance between the screen and the substrate), the printing pressure (the pressing force of the squeegee against the screen) and the squeegee speed, and simultaneously with the passage of the squeegee 3. Since the substrate 21 and the screen 20 are separated from each other, the flux 23 can be reliably transferred to the electrode pad 22 portion of the substrate 21. The screen 20 is fixed to the plate frame 20c.

  The viscosity of the screen printing flux 23, thixotropy, and the fineness of the diameter of the opening 20k of the screen 20 are affected, and the condition of the opening 20k of the screen 20 after printing is completely within the opening in the normal printing state. However, the flux 23 is not lost, but a thin film can be formed.

  If the opening 20k of the screen 20 becomes clogged due to factors such as bleeding, scattering, and drying of the flux 23, or if the plate separation or transferability is deteriorated, the printing result becomes uneven. The print status can be determined by checking the printing screen 20 without checking the substrate 21. 6 (c), (1) shows a normal state of the screen opening, (2) shows a partially clogged state, and (3) shows a totally clogged state. . In the portion where the transfer amount to the substrate side is large, the residual amount of flux to the opening side of the screen is small, and on the contrary, in the portion where the transfer amount to the substrate side is small, the residual amount of flux to the opening side of the screen is large. . That is, the state where the printing state on the substrate 21 is reversed can be observed on the screen 20 side.

  Whether the screen 20 is open or not is determined as follows. The opening state of the screen 20 is imaged by the CCD camera 15, and the captured image is taken into the printing press control unit 30 via the image input unit 37. Subsequently, the image of the reference model of the opening state of the screen 20 stored in advance in the dictionary 38 is compared with the image of the opening state of the screen 20 captured in the above, and the dimension calculation unit 34 determines whether the “normal” or “bad” ( NG) ". As a result of the determination, “normal” indicates that the screen opening is in a normal state, and “bad” (NG) indicates a state in which the screen opening is partially clogged or clogged. .

  The opening state of the screen 20 determined to be defective (NG) after printing the flux is shown in (2) and (3) of FIG. In (2), the printing appears completely uneven and the pattern appears mottled. This detection can be easily made by pattern matching using a black and white camera.

  On the other hand, in the case of NG as shown in (3), the flux 23 is not printed on the substrate 21 but remains in the opening 20k portion of the screen 20 in a large amount. For this reason, since the degree of the remaining flux can be determined based on the difference in color density, it can be easily determined by comparison using a gray scale model based on image processing. Alternatively, it may be determined by color difference comparison using a color camera.

  In order to confirm the state of the opening of the screen 20 with the positioning CCD camera 15, a stable image is obtained by illuminating upward from the lower part of the screen 20 and confirming with the CCD camera disposed above the screen 20. Can be taken. A method of applying illumination from the upper side to the lower side of the screen 20 may be taken. Since the CCD camera 15 has upper and lower cameras (imaging units), when it is used as a positioning camera for imaging a positioning mark, upward and downward cameras are used, and the state of the opening of the screen 20 after printing is determined. When used as an inspection camera for observation, the upper camera is used.

  After the state of the screen 20 is inspected, if the NG signal such as clogging of the screen opening or flux contamination is issued from the dimension calculation unit 34, the inspection result is provided in the printing apparatus by a command from the printing press control unit 30. Cleaning is automatically carried out by the underlay cleaning device 45 (see FIG. 5), and the flux 23 is supplied and replenished as necessary. In addition, the substrate which has become NG is made to stand by on a conveyor in a subsequent process according to an instruction from the printing press controller 30 together with an NG signal so as not to perform the processes after the solder ball printing, and is discharged out of the line. The magazine may be discharged in a batch by using an inline NG substrate stocker or the like. The NG substrate can be used again for flux printing after being washed in an off-line process.

  Next, a pad surface inspection method using a camera using inner diameter side illumination will be described with reference to FIG. The flux 23 printed and transferred to the electrode pad 22 is difficult to identify the presence or absence of the flux 23 because the illumination light easily passes through the flux 23 in the reflected light microscope observation. When the diameter of the transferred flux 23 is larger than the diameter of the electrode pad 22 or when the transfer position is shifted and transferred to the outside of the electrode pad 22, the presence or absence of the flux 23 is confirmed by microscopic observation using a reflected light system. Although it is possible to determine the presence or absence of the flux 23 formed on the electrode pad 22, it is difficult to determine whether the transfer area is appropriate.

  Therefore, as shown in the lowermost diagram of FIG. 7, if the inspection method using the CCD camera 15 using the inner diameter side illumination 15L is used, the transferred flux 23 is illuminated not in the upper direction but in the outer circumferential direction of the flux 23. Thus, the flux 23 can be determined by the effect of raising the subject. As described above, automatic inspection can be handled by switching the illumination provided in the CCD camera 15 from downward illumination to inner diameter illumination 15L.

  In addition, by using a CCD camera 15 having an inner diameter illumination in combination with a mechanism that vertically moves up and down with the electrode pad 22 and a position measurement mechanism, by measuring the position of the top and bottom of the flux 23, The height of the flux 23 and the amount of the flux 23 can be measured.

  The discriminability is improved when the wavelength of the illumination used is blue light having a wavelength close to the ultraviolet region side in the visible light region.

  Furthermore, the fluorescent material is contained in the flux 23, and the printing result is observed with illumination having a wavelength in the ultraviolet region, so that the flux 23 can be easily discriminated by the light from the fluorescent material contained in the flux 23. .

  FIG. 8 shows the structure of a solder ball printing head (printing means, filling unit 60). The filling unit 60 includes a ball case that stores the solder ball 24 in a space formed by the housing 61, the lid 64, and the shib-like body 62, and a slit-like shape that is provided at a downward interval with respect to the shib-like body 62. It is composed of a body 63. The shib-like body 62 is formed of an extremely thin metal plate having a mesh-like opening or a continuous rectangular slit or the like so as to match the diameter of the solder ball 24 to be supplied. A slit-like body 63 is disposed below the shib-like body 62, and the slit-like body 63 is configured to be in surface contact with the screen 20b.

  The degree of contact and the gap of the slit-like body 63 with respect to the screen 20b can be finely adjusted by the print head lifting mechanism 4 not shown in the figure. The slit-like body 63 is made of a magnetic material and has an extremely thin opening having a mesh-like opening or a continuous rectangular slit so as to match the diameter of the target solder ball 24 and the opening size of the screen 20. It is made of a metal plate.

The screen 20b is formed by integrally forming a screen having a column (post structure) 20a on the printed pattern portion and a column made of nickel, and forming a sheet-like magnet made of neodymium having a surface magnetic flux density of 500 to 2000 G on the substrate mounting portion. A laid printing table 10 is provided. And by making the adsorption force by the magnetic force of the screen 20b and the printing table 10 be 10 to 100 gf / cm ² , the surface of the substrate 21 and the screen 20b can be brought close to each other so that there is no gap larger than the solder ball diameter. Become. If the attracting force is too weak, there is a gap between the lower portion of the screen 20b and the surface of the substrate 21, and the solder ball 24 enters and becomes a cause of failure.

When the substrate 21 is separated from the screen 20b after the printing is finished, the lowering speed and acceleration of the printing table 10 are controlled so that the peeling operation of the screen 20b flows from the periphery of the substrate toward the central portion. Uniform plate separation can be performed. However, if the attracting force by the magnetic force is too strong with respect to the screen tension, control becomes impossible.


Further, the magnetic attraction force between the slit-like body 63 of the printing means (filling unit) 60 and the screen 20b is set to 0. 0 by the printing table 10 in which a neodymium sheet magnet 10s having a surface magnetic flux density of 500 to 2000 G is laid on the substrate mounting portion. It is set to be 1 to 10 gf / cm ² . The slit body 63 for printing and the slit body for ball collection constituting the printing means (filling unit) 60 are made of SUS304, and the screen is made of nickel, so that the slit body 63 against the solder balls on the screen. However, the magnetic force generated from the printing table 10 acts uniformly and softly in the vertical direction on the screen 20b, so that the minute ball is held in the slit-like body 63 and the ball is not damaged by deformation. The operation of filling the opening 20d of the screen can be performed efficiently.

  FIG. 9 shows a horizontal vibration mechanism that vibrates a shim-like body 62 provided in a ball case 61 that is a solder ball storage portion of the printing means in the horizontal direction. A support member 70 having a vibration means 65 attached at a position parallel to the side surface of the ball case is provided on the top of the lid 64. With this configuration, the shib-like body 62 is vibrated by being vibrated by the vibration means 65 from the side surface side of the ball case. By vibrating the shib-like body 62, the slit-like opening provided in the shib-like body 62 can be opened larger than the diameter of the solder ball 24.

  As a result, the solder ball 24 housed in the ball case falls onto the slit-like body 63 from the slit portion of the shib-like body 62. The amount of the solder ball 24 dropped on the slit-like body 63, that is, the supply amount of the solder ball 24 can be adjusted by varying the vibration energy by the vibration means 65.

  The vibration means 65 shown in the figure uses an air rotary vibrator, and can control the frequency by finely adjusting the compressed air pressure by digital control. The frequency may be varied by changing the compressed air flow rate. Further, the shib-like body 62 and the ball case vibrate the solder balls 24 accommodated in the ball case by the vibration means 65 to cancel and disperse the suction force due to the Van Desworth force acting between the solder balls 24. The dispersion effect enables adjustment in consideration of production efficiency so that the supply amount of the solder balls does not change due to the influence of temperature and humidity in the material of the solder balls 24 and the production environment.

  FIG. 9 shows a horizontal swing mechanism of the filling unit 60. The slit-like body 63 is formed using a magnetic material. By using the magnetic material, the slit-like body 63 can be attracted to the screen 20 formed of the magnetic material by the magnetic force from the magnet built-in stage (printing table 10). As shown in FIG. 9, the horizontal swing mechanism is configured as follows. A linear guide 67 is provided above the support member 70, and a filling unit support member 71 provided with a linear rail so that the linear guide 67 can move is provided. The filling unit support member 71 is provided with a drive motor 68. An eccentric cam 66 provided on the drive motor shaft is attached, and the eccentric cam 66 rotates to move the support member in the left-right direction. It has a configuration.

  In other words, the horizontal swing mechanism in the horizontal direction gives a swing operation to the slit-like body 63 with an arbitrary stroke amount by rotating the eccentric cam 66 by the drive motor 68 as shown in FIG. is there. Since the slit-like body 63 swings while being attracted to the screen 20b by the magnetic force, it is possible to roll the solder ball 24 reliably without a gap between the slit-like body 63 and the screen 20b. In addition, an efficient filling operation is possible while the solder ball 24 is reliably captured in the opening 20d of the slit-like body 63 by the opening size of the slit-like body 63. The cycle speed of the screen 20 and the swing operation can be arbitrarily changed by controlling the speed of the driving motor 68, and the filling tact of the solder ball 24 can be set in consideration of the line balance. Further, the filling rate can be controlled by adjusting the material speed of the solder ball 24, the opening 20d of the screen 20b, and the cycle speed suitable for the environmental conditions.

  FIG. 11 shows a diagram of a configuration in which the filling head is provided with a spatula (solder ball collecting means). After the solder ball 24 is supplied onto the substrate 21 by the filling unit 60, when the screen 20b is separated from the surface of the substrate 21, that is, when the solder ball is transferred onto the substrate 21 by separating the plate, the solder ball is formed into the plate surface of the screen 20b. If there is a remainder of 24, the solder ball 24 falls onto the substrate 21 through the opening of the screen 20b, which causes a defect of the excessive solder ball. Therefore, in this embodiment, the spatula-like body 69 is provided at substantially the same height as the slit-like body 63 with an interval from the ball case in the traveling direction of the filling unit 60. The tip of the spatula 69 is polished to a very thin and highly flat state so that the solder ball 24 does not protrude from the filling unit 60 while being in close contact with the screen 20b. In this way, it becomes possible to collect excess solder balls by the spatula 69.

  Further, if the spatula-like body 69 is made of a magnetic material, it is attracted to the screen 20b by a magnetic force like the slit-like body 63, so that the solder ball 24 can be prevented from coming out of the filling unit 60. Note that the spatula 69 may be provided in the entire outer peripheral portion of the ball case 61.

  Furthermore, the spatula-like body 69 is formed of a porous chamber foam having holes sufficiently larger than the diameter of the solder ball, so that printing can be performed while the solder ball 24 is efficiently captured.

  In FIG. 12, the figure of the structure which provides an air curtain in the filling unit 60 is shown. The spatula 69 can prevent the ball remaining on the plate surface of the screen 20b from being almost absent, but the influence of the ball remaining due to a minute displacement of the plate surface of the screen 20b can be considered. Therefore, in this embodiment, an air curtain is installed in order to eliminate defects caused by excessive solder balls. That is, an air jet 75 is provided on a motor support member that supports a head lifting mechanism (vertical movement motor) 4 constituting the print head 2 so that an air curtain is formed around the filling unit. The jet outlet 75 is configured to be supplied with compressed air from a compressed air supply source (not shown).

  By this air curtain, when the filling unit moves in the direction of the substrate end face, the protruding ball is pushed and rolled by the compressed air toward the filling unit operation direction side, so that there is no remaining ball on the plate surface.

  FIG. 13 is a diagram for explaining the screen filling state inspection after solder ball printing. 13 (a) and 13 (b) are the same as those in FIG. 6, and a description thereof is omitted here.

  The solder ball filling state on the screen 20b after the solder ball filling / printing is shown in (1) to (3) of FIG. The state in which the solder balls 24 are completely filled in the openings of the screen 20b can be observed as shown in (1). (2) shows a state where solder ball filling is incomplete. (3) shows a double ball state in which a plurality of solder balls 24 are adsorbed at the time of filling, and a state in which excessive solder balls remain on the plate surface of the screen.

  Even if the plate is released in the states (2) and (3) and the substrate is passed to the subsequent process, a rejected product is produced. Therefore, before carrying out the plate separation operation, it is possible to correct the rejected product to a non-defective product by retrying the filling / printing operation by the filling unit 60 by inspecting the filling state on the plate surface of the screen 20b. is there. This detection can be made by pattern matching compared with a non-defective model. After the solder ball filling and printing, the line sensor camera attached to the print head side performs batch recognition in units of areas. If it is NG, the solder ball filling / printing is executed again. If it is acceptable, the plate separation operation is executed and the substrate 21 is discharged to the subsequent process.

  FIG. 14 is a diagram for explaining the repair work in the inspection / repair unit after filling the solder balls. FIG. 15 is a diagram for explaining a filling failure situation after solder ball filling. As shown in FIG. 15, the solder ball filling failure includes failure modes such as no balls, double balls, misaligned balls, and excessive balls.

  In the inspection / repair unit, first, after the solder ball filling / printing is completed, the filling state on the substrate is confirmed by a CCD camera. When a defect is detected, the position coordinates of the defective part are obtained. In the case of defects such as double balls, misaligned balls, crushing, and excessive balls, the vacuum suction nozzle 86 for suction is moved to the position of the solder ball, vacuum suctioned and moved to the defective ball disposal station, and vacuum break A disposal box is provided to drop and discard the ball.

  When an electrode pad portion that is not supplied due to insufficient supply of the solder ball 24 is detected, the normal solder ball 24 stored in the solder ball storage portion 84 is adsorbed by the dispenser 87 and is supplied to the flux supply portion 85. The dispenser 87 that adsorbs the solder balls 24 to the accumulated flux 23 is moved, and the solder balls 24 are immersed in the flux 23, whereby the flux 23 is added to the solder balls 24. The repair operation is completed by moving the dispenser 87 that has adsorbed the solder balls 24 added with the flux 23 to the defective portion of the substrate and supplying the solder balls to the defective portion.

  In the previous inspection, when the defective ball is removed with a crushed ball, a misaligned ball, or the like, the defect can be repaired by the repair work described above.

  FIG. 16 illustrates a schematic configuration of the inspection / repair device. In this figure, the inspection / repair unit is shown as one independent device.

  The inspection target substrate 82 is conveyed on the carry-in conveyor 88 on the inspection unit conveyor 90 in the direction of the white arrow. A gate-type frame 80 is provided on the inspection unit conveyor 90, and a line sensor 81 is provided on the loading-side conveyor 88 side of the gate-type frame 80 in a direction perpendicular to the substrate transport direction (the direction of the white arrow). is there. The line sensor 81 detects the state of the solder ball 24 printed on the electrode pad 22 on the substrate 21.

  Further, on one foot side that supports the portal frame 80, a solder ball storage portion 84 that stores normal solder balls and a flux supply portion 85 are provided. A disposal box is provided on the other foot side. The gate-shaped frame portion is provided with a vacuum suction nozzle 86 for sucking and removing defective solder balls and a dispenser 87 for repairing defects on the substrate, which can be moved left and right by a linear motor. Thus, the vacuum suction nozzle 86 and the dispenser 87 can be moved in the hatched arrow direction.

  The inspection section conveyor 90 is configured to reciprocate in the direction of the white arrow. According to the defect position of a board | substrate, it is comprised so that a defect position can be match | combined with a dispenser or a vacuum suction nozzle position. The substrate that has been inspected / repaired is carried out by the carry-out conveyor 89 and sent to the reflow apparatus. With the above-described configuration, inspection repair can be performed by the operation described with reference to FIG.

  As described above, it is possible to realize a printing apparatus that can accurately supply solder balls to the electrode pad portion of the substrate and can prevent generation of defective products as much as possible.

It is a schematic diagram of the flux printing and solder ball filling / printing process of the embodiment of the present invention. It is process explanatory drawing of a solder ball printer. It is a flowchart of bump formation. It is a figure which shows schematic structure of a screen printing apparatus. It is operation | movement explanatory drawing of a screen printing apparatus. It is explanatory drawing of the outline | summary of the test | inspection and repair apparatus after flux printing. It is explanatory drawing of the pad surface inspection method by the camera which uses inner diameter side illumination. It is a figure which shows the structure of a solder ball printing head. It is a figure which shows the horizontal vibration mechanism to a solder ball | bowl storage part shib-like body. It is a figure which shows the horizontal rocking | fluctuation mechanism of a solder ball printing head. It is explanatory drawing of the spatula for solder ball printing heads. It is explanatory drawing of the air curtain for solder ball printing heads. It is explanatory drawing of the example of the state of the screen after solder ball printing. It is explanatory drawing about repair of a solder ball. It is explanatory drawing of the state of solder ball printing failure. It is explanatory drawing of the outline | summary of a test | inspection and repair apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printing machine, 2 ... Print head, 3 ... Squeegee, 10, 10b ... Printing table, 10s ... Neodymium magnet, 11 ... XYtheta table, 15 ... Camera, 20, 20b ... Screen, 20a ... Strut, 20d ... Opening 21 ... Substrate, 30 ... Printing machine control unit, 34 ... Dimension calculation unit, 45 ... Cleaning device, 60 ... Printing means (filling unit), 63 ... Slit-like body, 65 ... Excitation means, 69 ... Spatula-like body, DESCRIPTION OF SYMBOLS 101 ... Flux printing part, 102 ... Flux inspection / repair part, 103 ... Solder ball filling / printing part, 104 ... Inspection / repair part

Claims (5)

A flux printing unit that prints flux on the electrode pads of the substrate, a solder ball filling / printing unit that supplies solder balls onto the flux-printed electrode, and a state of the substrate on which the solder balls are printed, In the solder ball printing device consisting of the inspection / repair unit that repairs depending on the defective state,
A flux inspection / repair unit is provided between the flux printing unit and the solder ball filling / printing unit to inspect the state of the substrate on which the flux has been printed and repairs depending on the defective state. The part includes a screen for supplying a solder ball to the substrate, and a printing unit having a slit-like body for filling the screen with the solder ball.   The solder ball filling / printing unit includes a magnetic printing table on which a substrate is placed, the metal screen having an opening that contacts the substrate and supplies solder balls onto electrodes of the substrate, Printing means having a slit made of metal, which is disposed above the screen and fills a solder ball in the opening of the screen, the magnetic attraction force of the printing table and the screen, the screen and the slit The solder ball printing apparatus according to claim 1, wherein the solder ball printing apparatus is set to be larger than the magnetic attraction force.   3. The solder ball printing apparatus according to claim 2, wherein the printing table includes a neodymium magnet, the screen is formed of nickel, and the slit-like body of the printing unit is formed of SUS304. 4. The magnetic attraction force between the printing table and the screen is set to 10 to 100 gf / cm ² , and the magnetic attraction force between the screen and the slit-like body is set to 0.1 to 10 gf / cm ^2. The solder ball printer according to claim 2 or 3.   The solder ball printing apparatus according to claim 2, wherein a neodymium magnet having a surface magnetic flux density of 500 to 2000 G is provided on the printing table.

Images