JP4021927B2 - Electronic component mounting method and apparatus - Google Patents

Description

  The present invention relates to an electronic component mounting method and apparatus for mounting electronic components on a circuit board with high accuracy, and in particular, even if the mounting positions of the electronic components are narrow, the self-alignment effect is effectively used to cause mounting defects. The present invention relates to a technique for performing mounting without doing so.

  For example, as shown in FIG. 29, a process of manufacturing a circuit board on which electronic components are mounted includes a printing process A in which cream solder is printed on a circuit board on which lands are formed by a cream solder printing apparatus, and a cream by an inspection apparatus. There are an inspection process B for inspecting the printed state of solder and a mounting process C for mounting electronic components on a circuit board by an electronic component mounting apparatus. The cream solder printing device, the inspection device, and the electronic component mounting device are respectively connected in this order on the production line, and the circuit board supplied to the production line is taken out through each process A, B, C, not shown. It is sent to the reflow process.

  Meanwhile, recent electronic components mounted on a circuit board have a mounting interval narrowed to about 0.15 mm, and tend to be further reduced in the future. In order to reduce the interval between the components to be mounted, it has been promoted to make the soldering state of the electronic component a filletless, but in order to make the filletless, the molten solder as shown in FIG. “Extended wetting” that gets wet through the terminal end face must be prevented. For this reason, the width of the land formed on the circuit board is set to be equal to or smaller than the terminal width of the electronic component so that the solder does not wet and spread on the terminal end face. That is, by setting the width of the land to be equal to or smaller than the terminal width of the electronic component, excess solder is not attached to the terminal end face, and the solder is prevented from greatly getting wet from the terminal face on the land side.

  When soldering an electronic component to the land, cream solder is printed on the land, the electronic component is mounted in accordance with the land position, and then reflow processing is performed. By this reflow processing, the cream solder sandwiched between the land and the terminal of the electronic component melts and flows, and the electronic component moves to the center position of the land by the self-alignment effect. Thus, mounting is performed while positioning to the land position.

JP-A-7-22791

  However, in the above conventional soldering method, the electronic component is mounted with the target mounting position aligned with the land position. Therefore, if the cream solder printing position deviates from the land position, soldering is performed after the reflow process. There is a problem that causes defects. Here, FIG. 31A is a diagram showing a state in which the electronic components are mounted on the printed circuit board with the cream solder being shifted from the land position so as to match each land center position, and FIG. It is a figure which shows the result of having performed the reflow process of the circuit board.

  If cream solder protrudes from the end of the electronic component as shown in the figure, the positional relationship between the mounted electronic component and the printed cream solder is “expanded” between the solder and the electronic component end during reflow. Wetting "occurs. As a result, the solder spreads unnecessarily on the side surface of the electronic component terminal, and a bridge is generated between adjacent electronic components or terminals. This bridge did not occur if the mounting interval of the electronic components was long, but the frequency of occurrence increased particularly for circuit boards with a small mounting interval of electronic components, which greatly reduced the quality of the mounted circuit board. It was. Also, the circuit board land position and cream solder printing position can be fine-tuned by the cream solder printing device. Is difficult, and it is substantially extremely difficult to completely correct the local misalignment.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electronic component mounting method and apparatus that can effectively utilize the self-alignment effect even when the mounting interval between electronic components is narrow. To do.

To achieve the above object, the electronic component mounting method according to claim 1 of the present invention is an electronic component mounting method for mounting an electronic component by printing cream solder on a circuit board on which lands are formed. A printing position detecting step for detecting a printing position of the cream solder on the substrate; and a mounting step for mounting the electronic component on the basis of the printing position of the cream solder. In the mounting step, the mounting is performed on the circuit board. The position shift amount between the position of the land corresponding to each electronic component to be printed and the printing position of the cream solder with respect to the land is obtained, and the circuit according to the tendency of the size of the position shift amount at each position on the circuit board characterized in that the substrate to set the pattern to be divided into a plurality of blocks in an annular or lattice-like, the target mounting position obtained by correcting the mounting position of the electronic component for each block To.
The electronic component mounting apparatus according to claim 5 of the present invention is an electronic component mounting apparatus that mounts an electronic component by printing cream solder on a circuit board on which lands are formed. And a mounting device for mounting the electronic component on the basis of the cream solder printing position, and the mounting device is mounted on the circuit board. The position of the land corresponding to the land and the printing position of the cream solder with respect to the land is obtained, and the circuit board is annularly or according to the tendency of the position deviation amount at each position on the circuit board. A pattern that is divided into a plurality of blocks is set in a grid pattern, and a target mounting position in which the mounting position of the electronic component is corrected is set for each block.

In this electronic component mounting method (electronic component mounting apparatus) , the print position of the cream solder on the circuit board is detected by the print position detection step, and the electronic component is detected based on the detected cream solder print position in the mounting step (mounting step) . When the cream solder is melted by the reflow process, the self-alignment effect that the electronic components are returned to the land position by the flow of the cream solder can be kept large, and the printing position of the cream solder has shifted from the land position. Even in this case, the electronic component can be securely fixed at the land position. Further, even when the mounting interval between electronic components is narrow, the self-alignment effect can be effectively utilized to improve the mounting position accuracy of the electronic component.

Also, in this electronic component mounting method (electronic component mounting apparatus) , the circuit board is divided into a plurality of blocks, and the amount of positional deviation between the land position corresponding to the electronic component mounted in each block and the printing position of the cream solder For each. A target mounting position of the electronic component is set for each block based on the obtained positional deviation amount of each block. As a result, even if the amount of misalignment tends to differ from block to block, an appropriate target mounting position can be set within each block. A shift from the mounting position is prevented from becoming large, and a uniform self-alignment effect is obtained over the entire circuit board, and mounting can be performed with high alignment accuracy.

In the electronic component mounting method according to claim 2, in the setting of the target mounting position of the mounting step, an average value of the positional deviation amount is obtained for each block, and the average value of each obtained block is used. The mounting position of the electronic component is corrected for each block .

In the electronic component mounting method according to claim 3 , in the division into a plurality of blocks of the circuit board in the mounting step, when the peripheral portion tends to have a larger amount of displacement than the center portion of the circuit board, A division pattern obtained by dividing an area into a ring from the periphery of the circuit board toward the center is set .

5. The electronic component mounting method according to claim 4, wherein in the mounting step, the circuit board is divided into a plurality of blocks, and the positional deviation amount tends to be larger at a position away from the corner than the corner of the circuit board. If there is, a division pattern in which the circuit board is divided into regions in a lattice shape is set.

  According to the electronic component mounting method and apparatus according to the present invention, the printing position of the cream solder on the circuit board is detected by the printing position detection step, and the electronic component is mounted based on the detected printing position of the cream solder in the mounting step. Therefore, when the cream solder is melted by the reflow process, the self-alignment effect that the electronic components are returned to the land position by the flow of the cream solder can be kept large, and even if the printing position of the cream solder deviates from the land position, The parts can be securely fixed at the land position. Further, even when the mounting interval of electronic components is narrow, the self-alignment effect can be effectively used to improve the mounting position accuracy of the electronic components.

  Embodiments of an electronic component mounting method and apparatus according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a process from printing cream solder on a circuit board on which lands are formed to mounting electronic components. In the present embodiment, first, the circuit board is supplied to the cream solder printing apparatus 100, and the cream solder is printed in correspondence with the land position on the circuit board. Next, the subsequent inspection apparatus 200 recognizes the land and the cream solder and inspects the positional deviation between the two. The inspection result is further transmitted to the subsequent electronic component mounting apparatus 300, and the circuit board on which the cream solder is printed is supplied to the electronic component mounting apparatus 300. The electronic component mounting apparatus 300 corrects the mounting position of the electronic component on the supplied circuit board based on the inspection result transmitted from the inspection apparatus 200, and mounts the electronic component at the corrected position. The above is the contents of the basic circuit board manufacturing process, but the present invention is characterized in that the electronic component is mounted on the basis of the printing position of the cream solder printed on the circuit board. In the present specification, cream solder refers to paste solder in which powder solder is mixed with high-viscosity flux.

  Here, the principle of the electronic component mounting method of the present invention for mounting the electronic component on the basis of the cream solder printing position will be described in detail. FIG. 2 is a diagram showing the positional relationship between the land on the circuit board, the printed cream solder, and the mounted electronic component. FIGS. 3 and 4 show the self-alignment effect of the mounted electronic component, respectively, as shown in FIG. It is explanatory drawing demonstrated in -P cross section.

  As shown in FIG. 2, here, the cream solders 16a and 16b are printed on the lands 14a and 14b formed on the circuit board 12 at positions shifted by a distance ΔL from the land center line Ll. In this case, the electronic component 18 is mounted according to the position of the cream solder 16a, 16b, and the center line Lc of the cream solder 16a, 16b substantially coincides with the center line Lp of the electronic component. When the reflow treatment is performed in this state, the cream solder melts and flows on the land. In the initial stage of this flow, as shown in FIG. 3A, the solder 20 spreads by wetting due to “immersion” generally observed during capillary penetration. As shown in FIG. 3B, when the solder 20 wets and spreads to both end faces 18a, 18a of the electronic component 18, the solder spread on the end face side of the component stops and only the solder on the land 14 side wets and spreads. Become. Then, the solder 20 moves the electronic component 18 in the direction of the arrow so as to be in a stable state that is balanced mechanically. This acts as a self-alignment effect, and the electronic component 18 is finally disposed at a position where the center line Ll of the land 14 and the center line Lp of the electronic component 18 coincide as shown in FIG.

  Further, the self-alignment effect may act as shown in FIG. That is, as shown in FIGS. 4A and 4B, when the solder 20 is melted, the electronic component 18 is moved along with the wetting spread due to “dipping wetness”, thereby obtaining a self-alignment effect. Then, as shown in FIG. 4C, when the wetting and spreading of the solder 20 on the land 14 is completed and the solder 20 is in a stable state in which the solder 20 is dynamically balanced, the movement of the electronic component 18 is also stopped. Therefore, the electronic component 18 is finally arranged at a position where the center line Ll of the land 14 and the center line Lp of the electronic component 18 coincide.

  With such a self-alignment effect, when mounting an electronic component with the land position as a target mounting position, for example, when a positioning shift of 50 μm or more occurs, the probability that the positional shift of the electronic component is corrected is about 50%. On the other hand, when an electronic component is mounted with the printed cream solder position as a target mounting position, even if a positioning shift of 50 μm or more occurs, the position shift is corrected with a probability of 80 to 90% due to the self-alignment effect.

  Next, a configuration example of an electronic component mounting system for mounting electronic components using the self-alignment effect will be described below. Specific configurations of the cream solder printing apparatus 100, the inspection apparatus 200, and the electronic component mounting apparatus 300 according to the present embodiment are as follows. First, as a cream solder printing apparatus (hereinafter abbreviated as a printing apparatus) of the present embodiment, for example, the one having the configuration shown in FIG. 5 can be used. FIG. 5 is an external perspective view in which a part of the printing apparatus 100 is cut away. The printing apparatus 100 includes a circuit board transport unit 22 that loads and unloads the circuit board 12 to be printed with cream solder into the printing apparatus 100, and a circuit board 12 that is loaded on the lower surface of the printing mask 24. The moving table part 26 and the printing part 30 for printing cream solder by the squeegees 28a and 28b above the circuit board 12 positioned on the lower surface of the printing mask 24 are configured.

  According to this printing apparatus 100, the circuit board 12 is conveyed as follows. That is, the circuit board transport unit 22 receives the circuit board 12 carried in from a stocker or a line, and supplies the circuit board 12 to the table unit 26 disposed inside the printing apparatus 100. Then, the table unit 26 positions and fixes the supplied circuit board 12 and moves it to a predetermined position on the lower surface of the printing mask 24 of the printing unit 30. When the printing process by the printing unit 30 is completed, the table unit 26 conveys the circuit board 12 from the printing unit 30 to the circuit board conveyance unit 22. Thereafter, the circuit board transport unit 22 takes out the circuit board 12 from the table unit 26 and discharges the circuit board 12 to a transport outlet (not shown).

  Here, the detailed structure of the table unit 26 is shown in FIG. The table portion 26 fixes the circuit board 12 with a holding member 32, and can be moved and rotated by motor control in the X, Y, Z, and θ directions shown in the figure, and a position on the circuit board 12 A substrate recognition camera 36 for recognizing alignment marks and a mask recognition camera 38 for recognizing alignment marks on the printing mask 24 are provided.

  The board recognition camera 36 images an alignment mark provided in advance on the circuit board 12 to be printed supplied to the table section 26 by the circuit board transport section 22. By processing the captured image and recognizing the mark position, the position of the circuit board 12 is accurately managed and positioned at a predetermined position for printing with high accuracy.

  The mask recognition camera 38 captures an image of a registration mark provided in advance on the printing mask 24. By processing the captured image and recognizing the mark position, the circuit board 12 is positioned with high accuracy at an appropriate position according to the perforation pattern of the printing mask 24. In addition, the above-mentioned circuit board conveyance part 22 and the table part 26 can be comprised by using the loader, unloader, and 4-axis stage which are generally used widely.

  FIG. 7 is a perspective view showing the printing unit 30 in a partial cross section. The printing unit 30 includes a pair of squeegees 28 a and 28 b on the upper side of the printing mask 24 in a state where the circuit board 12 fixed on the board mounting table 34 by the holding member 32 is arranged on the lower side of the printing mask 24. The solder paste is printed on the circuit board 12 by moving in both the front and rear printing directions. Here, the squeegee 28a is used during backward printing, and the squeegee 28b is used during forward printing.

  After the cream solder is printed on the land position formed on the circuit board 12 using the printing apparatus 100 having the above-described configuration, the printed circuit board 12 is taken out from the printing apparatus 100 and supplied to the inspection apparatus 200 at the subsequent stage. Next, the configuration of the inspection apparatus will be described. FIG. 8 is an external perspective view showing a configuration of the inspection apparatus 200 with a part cut away. The inspection device 200 includes a printing position detection device that detects the printing position of the cream solder printed on the circuit board. The inspection apparatus 200 includes a substrate transport unit 40 that transports the supplied circuit board 12, a light source 44, 44 such as a fluorescent lamp that illuminates the circuit board 12 stationary at the inspection position 42 from an oblique direction, and a circuit. An imaging camera 46 that images the substrate surface from above the substrate 12 is provided. In this inspection apparatus 200, the circuit board 12 illuminated by the light sources 44 and 44 is imaged by the imaging camera 46, and a captured image obtained thereby is imaged by a controller (not shown) disposed in the inspection apparatus 200. By processing, each land of the circuit board 12 and the printed cream solder are detected, and the corresponding deviation amount and the like are obtained. Information such as the obtained deviation amount is temporarily stored in the controller and transmitted as an inspection result to the subsequent electronic component mounting apparatus 300. The inspection result is fed back to the cream solder printing apparatus 100, and the cream solder printing apparatus 100 is adjusted so as to quickly correct the printing position shift of the cream solder.

  Next, the configuration of the electronic component mounting apparatus will be described. 9 is a perspective view of the electronic component mounting apparatus, FIG. 10 is an enlarged perspective view of the transfer head of the electronic component mounting apparatus, FIG. 11 is a block diagram showing the configuration of a control device that controls the electronic component mounting apparatus, and FIG. The block diagram which shows the structure of the mounting data used for a component mounting apparatus was shown. The configuration of the electronic component mounting apparatus 300 will be briefly described. As shown in FIG. 9, the electronic component mounting apparatus 300 is provided with a guide rail 52 of the circuit board 12 at the center of the upper surface of the base 50. Then, the circuit board 12 is conveyed from the board carry-in part 54 on one end side to the mounting position 56 for electronic components and from the mounting position 56 to the board carry-out part 58 on the other end side. Y tables 60 and 62 are provided on both sides of the upper surface of the base 50 above the circuit board 12, and an X table 64 is suspended between the two Y tables 60 and 62. In addition, a transfer head 66 is attached to the X table 64, so that the transfer head 66 can be moved in the XY plane.

  The transfer head 66 mounted on the XY robot including the X table 64 and the Y tables 60 and 62 and freely moving on the XY plane (horizontal plane) is supplied with electronic components such as a resistor chip and a chip capacitor. A desired electronic component is held by a suction nozzle 72 from a component supply unit 68 or a component supply tray 70 to which a relatively large electronic component such as an IC or connector such as SOP or QFP is supplied. After detecting the suction posture of the electronic component, the electronic component is mounted at a predetermined position on the circuit board 12. The electronic component mounting operation is controlled by the control device based on a preset mounting program (collectively referred to as mounting data). Note that data can be directly input to the control device through the operation panel 76.

  A large number of component supply units 68 are arranged in parallel at both ends of the guide rail 52, and each component supply unit 68 has a tape-shaped component roll containing electronic components such as a resistor chip and a chip capacitor. It is attached. In addition, the component supply tray 70 can be loaded with a total of two trays 70a that are elongated in the direction orthogonal to the guide rail 52, and each tray 70a slides toward the guide rail 52 according to the number of components supplied. In this configuration, the component removal position in the Y direction is maintained at a fixed position.

  On the side of the circuit board 12 positioned on the guide rail 52, a two-dimensional displacement (suction posture) of the electronic component held by the suction nozzle 72 is detected, and this displacement is transferred to the transfer head 66 side. A recognition device 74 is provided for making corrections. A posture recognition camera is provided on the inner bottom portion of the recognition device 74, and a light emitting element such as a light emitting diode LED for illuminating an electronic component held by the suction nozzle 72 is multi-staged on the inner surface of the casing around the posture recognition camera. A plurality are provided. Thereby, light can be irradiated from a desired angle to the mounting surface of the electronic component, and imaging can be performed at an appropriate illumination angle according to the component type. This illumination angle is set for each electronic component by preset component recognition data. The obtained image data obtained by the recognition device 74 is subjected to recognition processing by the control device, and the center position, electrode position, and the like of the electronic component are recognized and used for correction data of the mounting position and angle.

  As shown in FIG. 10, the transfer head 66 has a plurality (four in this embodiment) of mounting heads (first mounting head 78a, second mounting head 78b, third mounting head 78c, and fourth mounting head 78d. ) Are connected side by side as a multiple head. The four mounting heads 78a to 78d have the same structure. The suction nozzle 72, the actuator 80 for causing the suction nozzle 72 to move up and down, the motor 82 for rotating the suction nozzle 72 itself, and the timing belt 84. And a pulley 86. The suction nozzle 72 of each mounting head is replaceable, and the other suction nozzles are stored in advance in a nozzle stocker 88 on the base 50 of the electronic component mounting apparatus 300. The suction nozzle 72 includes, for example, an S size nozzle that holds a microchip component of about 1.0 × 0.5 mm, an M size nozzle that holds an 18 mm square QFP, and the like, which is selected according to the type of electronic component to be mounted. To be used.

  Here, as shown in a block diagram of the main configuration in FIG. 11, the control device digitally converts and captures the image signal from the posture recognition camera of the recognition device 74 and captures the inspection result from the inspection device 200. / O processing circuit 90, a microcomputer 92 that captures digital data via the I / O processing circuit 90 and performs various information processing such as image processing, an image memory 94 that stores image data, and a predetermined control program And a database 96 storing various mounting data for executing the above. Further, the control device controls the Z-axis movement of the X-axis and Y-axis movement control motors 98a and 98b shown in FIG. 9 and the mounting heads 78a to 78d shown in FIG. Motors 98c (actuators 80) and X-axis, Y-axis, Z-axis, and θ-axis drivers 99a to 99d for driving a θ-axis movement control motor 98d (motor 82).

  Further, the control device is an information storage medium (for example, a magnetic recording medium, a magneto-optical recording medium, an optical recording medium, etc.) in which mounting data for performing mounting operation for mounting electronic components on at least the circuit board 12 is stored, or A reading device 112 that reads the mounting data from a solid-state storage element 110 such as a flash memory is provided. The provision of the mounting data by the information recording medium 110 may be performed via a network as a communication line.

  As the mounting data, as shown in FIG. 12, the NC program 114 in which information such as the mounting position on the circuit board 12, the component supply position in the component supply unit 68 or the component supply tray 70, and the mounting order is recorded. An arrangement program 116 in which information on the allocation of electronic components to the component supply position is recorded, a component library 118 in which information on the shape of electronic components is recorded, and information on board mark shapes such as circuit board alignment marks are recorded. In addition, there is a mark library 120, substrate data 122 in which information on the shape and land shape of the circuit board is recorded, and the like.

  Next, a mounting operation by the electronic component mounting apparatus 300 having the above configuration will be described. First, the circuit board 12 carried out from the above-described inspection apparatus 200 is carried into the apparatus from the board carry-in portion 54 of the guide rail 52, and the circuit board 12 is conveyed to a predetermined mounting position 56. Further, the inspection result transmitted from the inspection apparatus 200 is input to the control apparatus. Next, the transfer head 66 is moved in the XY plane by the XY robot, and a predetermined electronic component is sucked and held from the component supply unit 68 or the component supply tray 70 based on a preset mounting program. Then, the transfer head 66 is moved onto the posture recognition camera of the recognition device 74 while holding the electronic component, and the suction posture of the electronic component is recognized. Thereby, the positional relationship between the suction nozzle 72 and the electronic component held by suction is detected. Then, based on the inspection result input from the inspection apparatus 200, the target mounting position of the electronic component is changed from the normally used land position to the cream solder printing position, and the suction nozzle 72 and the electronic device according to the recognized suction posture are changed. The positional deviation from the component is corrected, and the electronic component is mounted on the circuit board 12.

  In addition, as the change operation of the target mounting position and the correction operation according to the recognized suction posture, for example, the deviation amount in the X direction and the Y direction is given to the XY robot as an offset, and the deviation amount of the rotation component is set as the suction nozzle 72. Can be performed by rotating the motor 82 with the motor 82.

  Here, a procedure for changing the target mounting position of the electronic component from the normally used land position to the cream solder printing position based on the inspection result input from the inspection apparatus 200 will be described in detail with reference to the flowchart shown in FIG. . First, the circuit board 12 is carried into the printing apparatus 100, and cream solder is printed corresponding to each land formed on the circuit board 12 (S10). Then, the circuit board 12 is unloaded from the printing apparatus 100 and loaded into the subsequent inspection apparatus 200.

  In this inspection apparatus 200, as schematically shown in FIG. 14, the land 14 formed on the circuit board 12 and the cream solder 16 printed on the land 14 at the target position are illuminated by a light source 44. An image is taken by the imaging camera 46. Then, the obtained captured image was separated into the land portion 126 and the cream solder portion 128 by image processing from the luminance difference of each pixel and the like, and was sandwiched between the cream solder 16 and the circuit board 12 and was not imaged. The missing portion of the land is reproduced by interpolation processing using land data prepared in advance and registered in the land shape. For example, the land shape feature points (edge components such as captured corners and sides) other than the missing portion are accurately detected, and the land shape registered in the land data is detected from the position of the detected shape feature points. By estimating the positions of the remaining shape feature points while collating with each other, the complete land shape can be accurately reproduced.

Next, the center position of the land shape separated and reproduced in this way is measured (S11). Here, as shown in FIG. 15, any of the substrate marks 130 for alignment provided at the diagonal positions of the circuit board 12 (or may be individual marks provided for other purposes) is used as a reference position. lands 14a of the circuit board 12, the gravity center position O _L1 of _{14b (x 1, y 1)} , measured O _L2 and (x _2, y _2). Then, these gravity center position O _L1, O _L2 midpoint connecting the land center point _{O L (x L, y L} ) and.

Similarly, the solder printing position is measured from the separated cream solder portion 128 (S12). Here, as shown in FIG. 16, the respective gravity center positions O _C1 (x ₃ , y ₃ ) and O _C2 (x ₄ , y ₄ ) of the cream solders 16a and 16b printed on the circuit board 12 are measured. The midpoint connecting these gravity center positions O _C1 and O _C2 is defined as a cream solder center point O _C (x _C , y _C ). In this way, since the land center position O _L and cream solder center position O _C is obtained, these center position O _L, displacement amounts in the X and Y directions from O _C alpha, obtaining the beta (S13).

Next, the obtained deviation amounts α and β are compared with a predetermined deviation allowable value (S14), and when the deviation amounts α and β are equal to or larger than the deviation allowable value, as shown in FIG. Since there is a possibility that a deviation occurs in the rotation direction, the deviation θ in the rotation direction is measured (S15). Here, the shift amount θ is obtained by, for example, the equation (1).
θ = tan ⁻¹ {(y ₃ + y ₄ ) / (x ₃ −x ₄ )} (1)
If the deviation amounts α and β are smaller than the allowable deviation value, the measurement of the deviation amount θ in the rotational direction is omitted and θ = 0 is assumed, but even when the deviation amounts α and β are smaller than the allowable deviation value. The shift amount θ in the rotation direction may be positively obtained.

  2A and 2B, the electronic components 18 are set with reference to the cream solder printing position as shown in FIG. Mounting (S16). That is, the electronic component mounting apparatus 300 is arranged so that the center position of the electronic component 18 matches the center position of the cream solder 16a, 16b printed with the deviation amounts of α, β, θ with respect to the lands 14a, 14b. The electronic component 18 is mounted by controlling the X-axis motor 98a, the Y-axis motor 98b, the Z-axis motor 98c, and the θ-axis motor 98d (see FIG. 11) mounted on the XY robot or the mounting head.

  For example, the mounting position recorded in the NC program 114 of the mounting data shown in FIG. 12 is changed in addition to changing the target mounting position by sequentially changing the electronic component mounting apparatus 300 when mounting the electronic component. But you can. In addition to changing the target mounting position so as to correct 100% with respect to each deviation amount of α, β, and θ, it is assumed that the deviation amount is changed by an arbitrary ratio between 0 and 100%. Also good. In this case, fine adjustment can be performed to make the best use of the self-alignment effect that changes under delicate conditions, and an optimal mounting state can be obtained.

  According to the electronic component mounting method described above, by performing feedforward control of the print position detection result output in the print position detection process to the mounting process, the circuit board that is the target for the solder paste print position detection is electronically controlled. The target mounting position of the component can be immediately set as the cream solder printing position reference. In addition, the self-alignment effect that the electronic components once mounted move to the regular land position by reflow processing is maximized, and even if the circuit board has a small mounting interval between the electronic components, the electronic components are not exposed on the side surfaces of the electronic component terminals. The generation of bridges due to the spread of solder as necessary is prevented, the quality of the mounted circuit board can be maintained at a high level, and high-density electronic components can be mounted stably. In addition, since the optimum target mounting position can be set for each electronic component, mounting accuracy can be improved. In this electronic component mounting method, it is possible to simply detect the cream solder printing position without mounting the land position, and mount the electronic component with this cream solder printing position as the target mounting position. .

  Next, a second embodiment of the electronic component mounting method according to the present invention will be described. In the first embodiment, for each electronic component mounted on the circuit board, the land position and the cream solder printing position are detected for each electronic component, and the deviation amount of both is obtained to mount the electronic component. Although the position has been changed, in this embodiment, for all the electronic components mounted on the circuit board, the deviation amount between the land position and the printed cream solder position is obtained, and the deviation with respect to each of these electronic components is determined. The average value of the amounts is obtained, and the electronic component mounting position on the circuit board is collectively changed based on the obtained average value of the deviation amounts.

Here, a specific change procedure will be described below. For example, when N electronic components are mounted on a circuit board, each deviation amount is set as follows in order of mounting with respect to NC data as mounting data.
Data 1: α ₁ , β ₁ , θ ₁ Data 2: α ₂ , β ₂ , θ ₂ Data 3: α ₃ , β ₃ , θ ₃ ... Data N: α _N , β _N , θ _N

From these deviation amounts, the X direction correction value, the Y direction correction value, and the θ direction correction value are set using the equations (2) to (4).
X direction correction value = (α ₁ + α ₂ + α ₃ +... + Α _N ) / N (2)
Y direction correction value = (β ₁ + β ₂ + β ₃ +... + Β _N ) / N (3)
θ direction correction value = (θ ₁ + θ ₂ + θ ₃ +... + θ _N ) / N (4)

  The correction values of the equations (2) to (4) are applied to all the electronic components mounted on the circuit board, and the target mounting position is changed and mounted. Thereby, compared with the case where a mounting position is individually changed with respect to each electronic component, the whole calculation processing amount is reduced and the speed of mounting operation is achieved.

  Next, a third embodiment of the electronic component mounting method according to the present invention will be described. In the second embodiment, the amount of deviation from the land of the solder paste printed on the circuit board is averaged, and the target mounting position is changed centrally for all electronic components. In this embodiment, Divide the circuit board into an arbitrary number of blocks, find the average deviation amount for each block, and use the obtained average value for each block to mount electronic components for each block The position has been changed.

  Here, as a pattern for dividing the circuit board into an arbitrary number of blocks, for example, the division pattern shown in FIG. 18 can be cited. FIG. 18A is an example in which the area is divided in an annular shape from the periphery of the circuit board toward the center. FIG. 18B shows an example in which the circuit board is divided into regions in a grid pattern. In the divided pattern shown in FIG. 18A, the shift amount of the central portion (region C) of the circuit board is small, and the shift amount tends to increase toward the peripheral portion (block A). The target mounting position of the electronic component is set using a small correction value for a small shift amount and a large correction value for a large shift amount in the block A, respectively. Further, in the division pattern shown in FIG. 18B, the shift amount is small at the corner (for example, the block A), and the shift amount tends to increase as the distance from the corner increases. The target mounting position is set using the correction value of the value and the correction value of a large value in the other blocks.

Specifically, when the number of area divisions (number of blocks) is M and the number of mounted parts in each block is Naj (j is 1 to M), a set deviation amount (correction value) αi in each block, βi and θi (i is 1 to M) are expressed by the equations (5) to (7).
αi = (αij +... + αiMNaj) / Naj (5)
βi = (βij +... + βiMNaj) / Naj (6)
θi = (θij +... + θiMNaj) / Naj (7)
Here, αij, βij, and θij are deviation amounts with respect to the j-th electronic component in the block i.

  Thus, by setting the correction value individually for each block, the target mounting position of the block with a small deviation amount is prevented from being greatly affected by the block with the large deviation amount, and the circuit is increased. Mounting can be performed with uniform alignment accuracy over the entire substrate.

  Next, a fourth embodiment of the electronic component mounting method according to the present invention will be described. In the present embodiment, as shown in FIG. 19, the weight and shape of the electronic component to be mounted, the material composition of the cream solder to be used, the friction property, the viscosity, the solder powder diameter, the melting point, the flux component (resin base, organic substance base, Various parameters such as inorganic base), flux activity, printing thickness and the like are tabulated, and the self-alignment rate is assumed according to the type of electronic component actually used and the combination of cream solder materials using this table. Here, the self-alignment rate is an index that expresses in percentage how much the self-alignment is effective from the center of the printed cream solder. Based on this self-alignment rate, how much (for example, 50%, 80%, 100%, etc.) the above-described cream solder printing position deviation amount is used as a correction value for setting a target mounting position is set.

  The cream solder parameter table is registered as part of the mounting data as the solder data 124 as shown in FIG. 12, but is not limited to this. For example, in the other data area such as the NC program 114 and the array program 116 It may be configured to be registered. In addition to the above parameters, the registered content may be the name of the cream solder manufacturer. In this case, each characteristic parameter corresponding to the model name is registered in advance in a table, and can be automatically set collectively from this table. This greatly simplifies the mounting data input operation.

  As described above, according to the present embodiment, the correction value can be appropriately changed for each mounted component according to the combination of the type of electronic component actually used and the type of cream solder, and more electronic components are mounted. A large self-alignment effect can be obtained. Further, since the correction value is set by directly reflecting the self-alignment effect, the component mounting accuracy can be further improved.

  Next, a fifth embodiment of the electronic component mounting method according to the present invention will be described. In the present embodiment, as shown in FIG. 20, since the size of the self-alignment effect is determined to some extent according to the cream solder printing position with respect to the land position, the cream solder printing position is set as the target mounting position, Whether to set the land position as the target mounting position is selectively set according to the printing position deviation state of the cream solder. Here, FIG. 20A shows a state where the cream solder is printed out of the center of the lands 14a and 14b, and in this case, a sufficient self-alignment effect can be obtained. FIG. 20B shows a state in which cream solder is printed out of the lands 14a and 14b. In this case, the cream solder is divided outside the land during reflow, and the self-alignment effect is reduced.

  In the present embodiment, the above-described self-alignment rate is assumed by detecting the cream solder printing state in this manner, and the target mounting position is determined according to the self-alignment rate. FIG. 21 shows a flowchart of the electronic component mounting method of the present embodiment. According to this, first, the land position and the land shape are imaged and recognized by the inspection apparatus 200 (S20). Further, the cream solder printing position and the printing shape are recognized (S21). The self-alignment rate is determined from the recognition result (S22). When the self-alignment rate is large, the cream solder printing position is set as the target mounting position (S23). When the self-alignment rate is small, the land position is targeted. The mounting position is set (S24). For this reason, when the printing misalignment of the cream solder is large, the electronic component is mounted at a position where the self-alignment effect cannot be sufficiently obtained, and the electronic component is fixed with the misalignment after the reflow process. Can be prevented.

  Next, a sixth embodiment of the electronic component mounting method according to the present invention will be described. In this embodiment, when electronic components are mounted with the cream solder printing position set as the target mounting position, it is conceivable that adjacent electronic components interfere with each other as shown in FIG. Is obtained by calculation in advance before mounting, thereby preventing the occurrence of mounting defects.

  Specifically, the contour of the electronic component is obtained from the mounting position of the electronic component recorded in the NC program 114 provided in the mounting data shown in FIG. 12 and the component size recorded in the component library 118, and the cream solder described above. It is determined whether or not there is interference between the contour at the mounting position after correcting the shift amount of the printing position and the contour of the adjacent component. When there is no interference, the mounting process is performed as it is, and when there is interference, the component is not mounted. Further, when there is interference, the mounting position may be corrected again to the position where the electronic components do not interfere with each other. In this case, the recovery process by stopping the mounting of the electronic component can be eliminated, and the mounting process can be speeded up. The mounting position correction may be performed by changing the target mounting position one by one at the time of mounting, or may be performed by rewriting the mounting position of the NC program 114. As a result, the occurrence of mounting defects can be prevented, and the productivity of the circuit board can be prevented from being lowered.

  Next, a modified example of the electronic component mounting system that realizes the electronic component mounting method of each embodiment described above will be described. FIG. 23 is a diagram illustrating a configuration example of an electronic component mounting system according to a first modification. In this modification, the cream solder printing apparatus 102 with an inspection function in which the function of the cream solder printing apparatus 100 and the function of the inspection apparatus 200 are integrated is used. The cream solder printing apparatus 102 in this case can be realized, for example, by using the substrate recognition camera 36 and the mask recognition camera 38 shown in FIG. 6 for detecting the land position and the cream solder printing position. Moreover, it is good also as a structure which adds a test | inspection part separately. According to this configuration, the installation space can be reduced and the circuit board transfer process can be simplified, thereby enabling higher-speed processing.

  FIG. 24 is a diagram illustrating a configuration example of an electronic component mounting system according to a second modification. In this modification, an electronic component mounting apparatus 302 with an inspection function, in which the functions of the above-described inspection apparatus 200 and the electronic component mounting apparatus 300 are integrated, is used. The electronic component mounting apparatus 302 in this case can be realized by using, for example, a board recognition camera that detects a board mark for alignment for detecting a land position and a cream solder printing position. Moreover, it is good also as a structure which adds a test | inspection part separately. Also with this configuration, the installation space can be reduced and the circuit board transfer process can be simplified, thereby enabling higher-speed processing.

  FIG. 25 is a diagram illustrating a configuration example of an electronic component mounting system according to a third modification. In this case, each of the cream solder printing apparatus 100, the inspection apparatus 200, and the electronic component mounting apparatus 300 is connected to the host computer 140, and each apparatus is controlled centrally by the host computer 140. The inspection result of the solder paste printing misregistration from the inspecting apparatus 200 is input to the host computer 140, and the host computer 140 outputs the input misregistration information to the electronic component mounting apparatus 300 to perform feedforward control. According to this configuration, the electronic component mounting system can be comprehensively managed, and even when there is a circuit board production line with a plurality of mounting systems, these can be easily connected and controlled.

  In the electronic component mounting system described above, the mounting data (mounting program) has been described as a method of creating on the electronic component mounting apparatus 300, but is connected to the electronic component mounting apparatus 300 via a communication line or a recording medium. It is good also as a system created with another external device (mounting data creation device). In this case, the mounting data created by the mounting data creation device can be loaded into the electronic component mounting device 300 to enable the mounting operation, and the mounting data can be created even when the electronic component mounting device 300 is performing the mounting operation. As a result, the data creation workability is improved and the operation efficiency of the production facilities can be improved.

  The electronic component mounting apparatus 300 described above has a configuration in which the circuit board on which the electronic component is mounted is fixed, and the transfer head on which the mounting head is mounted moves on the circuit board to perform the mounting operation. The invention is not limited to this. For example, as shown in FIGS. 26 and 27, the electronic component mounting method of the present invention can be similarly applied to an electronic component mounting apparatus having a rotary head.

  Here, FIG. 26 is an external view of an electronic component mounting apparatus provided with a rotary head, and FIG. 27 is a schematic cross-sectional view of the rotary head for explaining the operation of the rotary head. The electronic component mounting apparatus 400 mainly includes a component supply unit 150 that continuously supplies electronic components, and holds the electronic component at a predetermined component supply position of the component supply unit 150 and mounts the electronic component on a circuit board. And a XY table 154 for positioning the circuit board. According to this, the circuit board supplied from the board carry-in unit 156 is placed on the XY table 154 and the electronic component is held from the component supply unit 150 by the rotary head 152, and then an appropriate correction process is performed. Mounted on the circuit board. Then, the circuit board on which the component mounting is completed is carried out from the XY table 154 to the board carry-out unit 158.

  As shown in FIG. 27, the component supply unit 10 includes a plurality of component supply units 160 that accommodate a large number of electronic components arranged in a direction perpendicular to the paper surface. The parts are supplied to the parts supply position. The XY table 154 is provided so as to be movable between the board carry-in section 156 and the board carry-out section 158, moves to a position connected to the board carrying path of the board carry-in section 156, and receives the circuit board before component mounting. The circuit board is fixed and moved to the component mounting position of the rotary head 152. The circuit board 12 is repeatedly moved according to the mounting position of each electronic component. When the component mounting is completed, the XY table 154 moves to a position where the circuit board 12 is connected to the board carry-out unit 158, and the circuit board 12 is moved to the board carry-out unit 158. To send.

  The rotary head 152 has a plurality of mounting heads 162 that attract electronic components, a rotating frame body 164 that is rotatably driven by supporting the mounting head 162 on the peripheral surface so as to move up and down, and an index rotation driving of the rotating frame body 164. An intermittent rotation drive device 168 is provided. The mounting head 262 continuously rotates from the component supply position of the component supply unit 150 to the component mounting position on the opposite side by the rotation of the rotating frame body 164 and moves downward at the component supply position of the component supply unit 150. The electronic component is picked up, the electronic component is picked up at the component recognition position where the component recognition device is located, and the electronic component is mounted on the circuit board 12 by moving down at the component mounting position. The electronic component mounting method according to each of the above embodiments can also be applied to the electronic component mounting apparatus 400 having such a rotary head, and similar effects can be obtained.

  Here, a description will be given of the result of obtaining the difference in the self-alignment effect due to the difference between the mounting position of the electronic component and the printing position of the cream solder. FIG. 28 shows the result of comparing the self-alignment effect under two conditions. FIG. 28A shows a state in which cream solder is printed based on the land position and the electronic component is mounted at a position shifted by Δl, and FIG. 28B shows a state in which the cream solder is printed by shifting by Δl from the land position. FIG. 28 (c) is a graph showing the self-alignment rate in the cases (a) and (b). The horizontal axis of the graph is an average value when shifted in the X and Y directions, and the used electronic component is a so-called 0603 chip having a size of 0.6 mm × 0.3 mm. The self-alignment rate represents the probability of returning to a position within ± 10 μm with respect to the land center.

  As shown in the graph of FIG. 28C, when only the mounting position of the electronic component of FIG. 28A is shifted, self is accompanied by an increase in the shift amount Δl as compared with the case of mounting based on the printing position reference of FIG. The decrease in alignment rate is severe. For example, when the deviation amount Δl is 50 μm, (a) is reduced to 70%, whereas (b) is 90%. From this, it can be seen that by mounting the electronic component at the shifted cream solder printing position, a larger self-alignment effect can be expected than when mounting at the land position.

  The present invention relates to an electronic component mounting method and apparatus for mounting electronic components on a circuit board with high accuracy, and in particular, even if the mounting positions of the electronic components are narrow, the self-alignment effect is effectively used to cause mounting defects. This is useful for technology that implements without mounting.

It is a figure which shows roughly the process after printing cream solder on the circuit board in which the land was formed, and mounting an electronic component. It is a figure which shows the positional relationship of the land on a circuit board, the printed cream solder, and the electronic component mounted. It is explanatory drawing explaining the self-alignment effect of the mounted electronic component in the PP cross section of FIG. 2, respectively. It is explanatory drawing explaining the self-alignment effect of the mounted electronic component in the PP cross section of FIG. 2, respectively. It is the external appearance perspective view which notched and showed a part of printing apparatus. It is a figure which shows the detailed structure of a table part. It is the perspective view which displayed the printing part in the partial cross section. It is an external appearance perspective view which notches and shows the structure of a test | inspection apparatus partially. It is a perspective view of an electronic component mounting apparatus. It is an expansion perspective view of the transfer head of an electronic component mounting apparatus. It is a block diagram which shows the structure of the control apparatus which controls an electronic component mounting apparatus. It is a block diagram which shows the structure of the mounting data used for an electronic component mounting apparatus. It is a flowchart which shows the procedure which changes the target mounting position of an electronic component from the land position used normally to the printing position of cream solder. It is explanatory drawing which shows the outline of the content of the test | inspection by an inspection apparatus. It is explanatory drawing which shows a mode that the center position of a land shape is measured. It is explanatory drawing which shows each gravity center position OC1, OC2 of the cream solder printed on the circuit board, and deviation | shift amount (alpha) and (beta) of a X direction and a Y direction. It is explanatory drawing which shows deviation | shift amount (theta) of the rotation direction of the cream solder printed on the circuit board. It is a figure which shows the pattern which divides | segments a circuit board into arbitrary numbers of blocks, (a) is an example which divided | segmented area | region circularly toward the center from the periphery of a circuit board, (b) is an area | region in a grid | lattice form. It is a figure which shows an example divided | segmented. It is a figure which shows the combination of the kind of the electronic component actually used using this table, and the various parameters of the cream solder to be used, and various parameters of the cream solder to be used as a table. It is a figure which shows the printing state of the cream solder with respect to a land position, (a) is a state in which the cream solder was shifted from the center of the land, and (b) is a state in which the cream solder is printed out of the land. It is a flowchart in 5th Embodiment of the electronic component mounting method which concerns on this invention. It is a figure which shows a mode that adjacent electronic components interfere. It is a figure which shows the structural example by the 1st modification of the electronic component mounting system which implement | achieves the electronic component mounting method of each embodiment. It is a figure which shows the structural example by the 2nd modification of the electronic component mounting system which implement | achieves the electronic component mounting method of each embodiment. It is a figure which shows the structural example by the 3rd modification of the electronic component mounting system which implement | achieves the electronic component mounting method of each embodiment. It is an external view of the electronic component mounting apparatus provided with the rotary head. It is a schematic sectional drawing of the rotary head for demonstrating operation | movement of a rotary head. It is a figure which shows the result of having compared the self-alignment effect under two conditions. It is a figure which shows the process of manufacturing the circuit board by which the conventional electronic component was mounted. It is a figure which shows the "extended wetting" in which the molten solder gets wet by being transmitted to the terminal end surface of an electronic component. It is a figure which shows the soldering defect by the printing position shift of a cream solder, Comprising: (a) is a mode that the electronic component was mounted according to each land center position with respect to the circuit board printed by the cream solder shifting | deviating from the land position. (B) is a figure which shows the result of reflow processing of this circuit board.

Explanation of symbols

12 Circuit boards 14a and 14b Lands 16a and 16b Cream solder 18 Electronic component 20 Solder 44 Light source 46 Imaging camera 92 Microcomputer 96 Database 100 Cream solder printing device 102 Cream solder printing device with inspection function 110 Information recording medium 112 Reading device 116 Array program 118 Component Library 120 Mark Library 122 Board Data 124 Solder Data 126 Land Part 128 Cream Solder Part 140 Host Computer 200 Inspection Device (Print Position Detection Device)
300,400 Electronic component mounting device 302 Electronic component mounting device with inspection function ΔL Deviation amount Lc Cream solder center line Ll Land center line Lp Electronic component center line OL Land center Oc Cream solder center N Number of electronic components to be mounted M Number α, β, γ Deviation between land position and cream solder printing position

Claims (5)

An electronic component mounting method for mounting an electronic component by printing cream solder on a circuit board on which a land is formed,
A printing position detection step of detecting the printing position of the cream solder on the circuit board;
A mounting step of mounting the electronic component on the basis of the printing position of the cream solder;
In the mounting process,
On the circuit board, find the amount of positional deviation between the position of the land corresponding to each electronic component to be mounted and the printing position of the cream solder with respect to this land,
According to the tendency of the amount of displacement at each position on the circuit board, a pattern for dividing the circuit board into a plurality of blocks in a ring shape or a lattice shape is set, and the mounting position of the electronic component for each block An electronic component mounting method characterized by setting a target mounting position with the correction corrected. In setting the target mounting position of the mounting process,
The average value of the deviation amount is obtained for each block, and the mounting position of the electronic component is corrected for each block using the obtained average value of each block. Electronic component mounting method. In dividing the circuit board into a plurality of blocks in the mounting process,
2. A division pattern in which an area is divided in an annular shape from the periphery of the circuit board toward the center is set when the amount of deviation tends to be larger at the periphery of the circuit board than at the center. The electronic component mounting method described in 1. In dividing the circuit board into a plurality of blocks in the mounting process,
The division pattern in which the circuit board is divided into areas in a lattice shape is set when the shift amount tends to be larger at a position away from the corner than the corner of the circuit board. Item 2. The electronic component mounting method according to Item 1. An electronic component mounting apparatus for printing an electronic component by printing cream solder on a circuit board on which a land is formed,
A printing position detection device for detecting a printing position of the cream solder on the circuit board;
A mounting device for mounting the electronic component on the basis of the printing position of the cream solder;
The mounting apparatus is:
On the circuit board, find the amount of positional deviation between the position of the land corresponding to each electronic component to be mounted and the printing position of the cream solder with respect to this land,
According to the tendency of the amount of displacement at each position on the circuit board, a pattern for dividing the circuit board into a plurality of blocks in a ring shape or a lattice shape is set, and the mounting position of the electronic component for each block An electronic component mounting apparatus characterized by setting a target mounting position corrected for the above.

Images