JP6291426B2 - Mounting method and mounting apparatus - Google Patents

Description

  The present invention relates to a mounting method and a mounting apparatus for mounting a chip component such as an electronic component on a predetermined position of a substrate made of ceramics, resin, glass or the like placed on a substrate holding stage.

  In general, a mounting apparatus for mounting a chip component such as an electronic component on a substrate includes, for example, a bonding head that vacuum-holds the chip component, a mechanism that moves the bonding head in a vertical direction, a substrate holding stage that sucks and holds the substrate, A mechanism for moving the substrate holding stage in the horizontal direction and the rotation direction, and a two-field camera provided in a space between the bonding head and the substrate holding stage so as to be capable of moving back and forth and capable of simultaneously imaging the bonding head side and the substrate holding stage side. Have. In this mounting apparatus, a two-view camera is entered into the space, and the alignment mark written on the chip component held by the bonding head and the alignment mark written on the substrate are simultaneously read, and the chip component is based on the read information. Is aligned with the mounting position on the board. Then, after retracting the two-view camera, the head is lowered to join the chip component to the mounting position on the substrate (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2004-22949

  In recent years, the size of the substrate holding stage has been increasing for the purpose of increasing production efficiency, or a large number of substrates have been placed on the substrate holding stage. On the other hand, the demand for high-precision mounting such that the allowable range of positional deviation is 1 μm or less is increasing despite the increase in the mounting range due to the increase in the size of the substrate holding stage.

  As described above, a new problem has arisen in connection with an increase in the mounting range. This is the amount of positional deviation when the two-view camera is actually mounted on the substrate even though the positional deviation is 1 μm or less with the two-field camera between the bonding head and the substrate stage. Exists that exceeds several μm. This positional deviation amount is reproduced if the mounting position in the substrate holding stage surface is the same as the applied pressure at the time of mounting. Therefore, in the actual mass production process, an offset for offsetting this positional deviation amount is set. This ensures mounting accuracy. However, since this offset varies depending on the substrate, the chip, and the applied pressure during mounting, it is set individually for each mounting condition by trial and error.

  Here, since the alignment mark written on the chip component and the alignment mark written on the substrate are both on the bonding surface side, X-ray fluoroscopy is necessary to observe the alignment mark after mounting. Even just measuring the amount of subsequent positional deviation requires a lot of labor.

  As described above, in the method of setting the offset for each mounting condition, time is wasted, and chip components and substrates until the condition is set are also wasted.

  The present invention has been made in view of such circumstances, and a mounting method in which an offset is obtained if a position in a substrate holding stage surface on which a chip component is mounted and a pressurizing condition at the time of mounting are determined, and this An object of the present invention is to provide a mounting apparatus having a function of performing a mounting method.

In order to solve the above problem, the invention according to claim 1 is directed to pressurizing the chip component after the alignment mark of the chip component and the alignment mark of the substrate are recognized by the image recognition means and the chip component and the substrate are aligned. In the mounting method that mounts on the board, the mounting offset that offsets the amount of misalignment that occurs when the chip components are pressed and mounted after alignment is a function of the position within the surface of the board holding stage that holds the board and the pressure applied during bonding. In the mounting method, the function is derived based on a result obtained by obtaining a positional shift amount with respect to a plurality of conditions of applied pressure at each of a plurality of positions in the substrate holding stage surface. .

The invention according to claim 2 is the mounting method according to claim 1 , wherein an alignment mark is written when obtaining a positional shift amount with respect to a plurality of conditions of applied pressure at a plurality of positions in the substrate holding stage surface. The mounting method is characterized by using a transparent chip component.

According to a third aspect of the present invention, there is provided a bonding head for sucking and holding chip components, a mechanism for moving the bonding head in the vertical direction, a substrate holding stage for mounting and holding a substrate, and a bonding head and a substrate holding stage relative to each other. A mounting device having a mechanism for moving the head and the substrate holding stage in a horizontal direction and a rotating direction, and a two-field recognition means that is capable of moving forward and backward in the space between the bonding head and the substrate holding stage and can simultaneously image the head side and the substrate holding stage side. A mounting apparatus having a function of performing the mounting method according to claim 1 or 2 .

  By using the present invention, it is possible to easily obtain an offset that offsets the amount of misalignment that occurs when a chip component is pressed and mounted after alignment, and the productivity of the mounting process is improved.

It is a principal part front view of the flip chip mounting apparatus for enforcing the mounting method which concerns on one Embodiment of this invention. It is a figure explaining the board | substrate used for the mounting which this invention makes object. It is a figure explaining the simulation board | substrate and simulation chip | tip used for one Embodiment of this invention. It is a figure which shows the place which performs the positional offset amount evaluation of the simulation board | substrate and simulation chip which concerns on one Embodiment of this invention. It is a figure explaining the position shift of the alignment marks in one Embodiment of this invention. It is a figure explaining the data group obtained by one Embodiment of this invention. It is a flowchart of apparatus operation | movement and calculation in one Embodiment of this invention. It is a figure explaining the structure of the board | substrate holding | maintenance stage used in Example 1 of this invention. It is a figure explaining the simulation board | substrate used in Example 1 of this invention. It is the actual measurement data obtained in Example 1 of this invention. It is the data obtained from the approximate expression based on Example 1 of this invention.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a main part front view for explaining the basic functions of the mounting apparatus. This apparatus is a flip chip mounting apparatus 1 that joins the protruding electrodes 3 of the chip component 2 and the electrodes 5 of the substrate 4. For example, as shown in FIG. 2, the chip component 2 is mounted at a plurality of locations on the substrate 4. . The main part of this mounting apparatus is composed of a bonding head 6 that sucks and holds the chip component 2, a substrate holding stage 7 that sucks and holds the substrate 4, and a two-view camera 8 that is a recognition means. The holding stage 7 and the two-field camera 8 function according to instructions from the control unit 12.

  The bonding head 6 can be moved up and down, the substrate holding stage 7 is movable in the X, Y, and θ directions, and the substrate 4 is disposed below the bonding head 6 where the chip component 2 is to be mounted. To do. The two-field camera 8 is configured to be able to advance and retract so that it can be inserted between the bonding head 6 and the substrate stage 7, and alignment marks are respectively provided on the protruding electrode forming surface of the chip component 2 and the electrode forming surface of the substrate. Both alignment marks are read by the two-field camera 8, and either or both of the bonding head 6 and the substrate holding stage 7 are moved to perform precise alignment. After the precise positioning, the bonding head 6 is lowered and pressurized and heated as necessary to join the protruding electrode 3 of the chip component 2 and the electrode 5 of the substrate 4, but before the bonding head 6 is lowered. Further, the position of the substrate holding stage 7 is finely adjusted by an offset amount obtained as a function of the position in the surface of the substrate holding stage 7 and the applied pressure. A method for deriving the function for obtaining the offset will be described later.

  After this series of mounting operations is completed, the bonding head 6 is raised, and a new chip component 2 is transported to the bonding head 6 by a chip suction reversing tool (not shown), and the substrate holding stage 7 is moved, Next, the location of the substrate on which the chip component is to be mounted is placed under the bonding head. Thereafter, as in the previous description, a series of operations from alignment to joining using a two-field camera is performed.

  Further, after the mounting operation of the substrate 4 to all the locations where the chip components 2 are to be mounted is completed, the suction holding by the substrate holding stage 7 is released, and the substrate after the mounting is completed by a substrate transport tool (not shown). 4 is unloaded and a new substrate 4 is loaded and sucked and held by the substrate holding stage 7.

  Next, a method for deriving a function for obtaining an offset will be described. First, a method for acquiring data serving as a basis for deriving a function will be described using an example. FIG. 3 shows the alignment mark MC used to grasp the amount of positional deviation that occurs during pressurization at a plurality of locations (A1, A2,..., D7, D8 in FIG. 4) on the surface of the substrate holding stage 7. The simulated chip component 20 and the simulated substrate 40 on which the alignment mark MB is written. First, after the simulated substrate 40 is sucked and held by the substrate holding stage 7, the alignment mark MC of the simulated chip component 20 and the simulated substrate 40 alignment mark MB are used at any position of the plurality of locations using the two-view camera 8. After positioning and retracting the two-view camera 8, a predetermined pressure is applied, and the simulated chip component 20 and the simulated substrate 40 are bonded together using a transparent adhesive. Thereafter, the amount of positional deviation between the alignment mark MC of the simulated chip component 20 and the alignment mark MB of the simulated substrate 40 in the bonded state is measured using a recognition unit.

  Here, in order to clearly recognize each alignment mark, it is desirable that the simulated chip component 20 is transparent to visible light. Even if the simulated chip component 20 is made of silicon or the like that is opaque to visible light, it is possible to recognize the alignment mark after bonding by using X-rays or infrared rays. Because it is necessary to do so, the device becomes a large scale. On the other hand, if the simulated chip component 20 is transparent to visible light, the alignment mark after bonding can be recognized from above even with a visible light camera, and high resolution can be obtained even with a general-purpose camera. Further, since the two-field camera 8 can be diverted, the apparatus cost can be suppressed.

  As shown in FIG. 5, the actually measured deviation amount is obtained as a deviation amount ΔX in the X direction and a deviation amount Δ2 direction component in the Y direction, and the relationship between the position (x, y) on the substrate stage surface and the applied pressure, respectively. Record as data. The above data acquisition / recording is performed at a plurality of locations (A1, A2,..., D7, D8 in FIG. 4) on the surface of the substrate holding stage 7, and the same contents are obtained by changing the pressure at the same plurality of locations. Is performed using a new simulated substrate 40 to obtain and record data, and obtain a data group as shown in FIG.

  By using this data group, the amount of positional deviation is obtained by an approximate expression using the position and pressure force on the surface of the substrate holding stage 7 as variables, so that at any position and arbitrary pressure force on the surface of the substrate holding stage 7. Can be predicted. Therefore, since the offset cancels out this positional shift amount, an arbitrary position of the substrate holding stage 7 and an offset amount of an arbitrary applied pressure can be obtained. That is, the offset can be set as a function of the position in the surface of the substrate holding stage 7 and the pressure applied during bonding.

  A flowchart relating to the above offset calculation is shown in FIG. 7, and it is also possible to incorporate a function for automatically performing this series of operations and calculations into the control unit 12.

  Regarding the setting of a plurality of points on the surface of the substrate holding stage 7, it is desirable that the interval be in the range of about the same as the size of the chip component to be mounted by the target mounting apparatus to about three times. Since the actual mounting work interval is never smaller than the chip component, it is less necessary to make the interval smaller than the chip component, and if the interval is too large, an appropriate offset cannot be obtained due to a decrease in the accuracy of the approximate expression. Because.

  As described above, the embodiment for obtaining the offset from the position in the substrate holding stage surface and the applied pressure has been described. However, as the demand for further high-accuracy mounting increases, the position shift at the mounting stage due to the mounting temperature and the like is a problem. There is a possibility. In such a case, it is possible to examine the influence of factors such as temperature in addition to the position and the applied pressure, and use the factors as variables of the function for obtaining the offset.

Example 1
FIG. 8 shows the structure of the substrate holding stage 7 used in the first embodiment. A substrate holding stage 7 for sucking and holding the substrate 4 is disposed on a stage heater 9 for heating the substrate, and a copying mechanism 10 is provided between the stage heater 9 and the gantry 11. The movement of the substrate holding stage 7 in the XY directions is performed by moving the gantry 11. Here, the size of each element in the X direction × Y direction is 260 mm × 130 mm for the stage heater 9 and 250 mm × 120 mm for the substrate holding stage 7, and the copying mechanism 10 has a diameter of 114 mm. In the mounting using the substrate holding stage 7, there is no difference in position deviation due to the difference in position in the Y direction, and ΔY is almost zero, whereas a position deviation ΔX may occur depending on the position in the X direction. It was already known, and before mass production, an offset in the X direction was obtained for each position in the X direction by trial and error. Therefore, an attempt was made to functionalize the offset of the substrate holding stage 7.

  FIG. 9 shows the simulated substrate 40 used at that time, and the size is 240 mm × 64 mm. However, since the positional deviation amount does not change due to the difference in the Y-direction position of the substrate holding stage 7, FIG. Only the positional deviation amount for each position is obtained. In FIG. 9, the position No. 6 is the center in the X direction of the substrate holding stage. With this point as zero, the amount of misalignment between the simulated chip component 20 and the simulated substrate 40 is measured at intervals of 20 mm of 100 mm on each side. Went. In the measurement, the simulated chip component 20 and the simulated substrate 40 are made of transparent glass so that both the alignment mark MC of the simulated chip component 20 and the alignment mark MB of the simulated substrate 40 can be easily recognized. Note that, in the alignment step, the center misalignment between the alignment marks was set to 0.1 μm or less. The applied pressure was measured under three conditions of 50 (N), 100 (N), and 150 (N). As a result, the obtained result is as shown in FIG. From the result of FIG. 10, the amount of positional deviation when the applied pressure was changed in the range of 50 (N) to 150 (N) was obtained by an approximate expression, and FIG. 11 was obtained.

  Therefore, when the offset is set from the positional deviation amount at the time of the applied pressure 120 (N) obtained from FIG. 11 and bonding is performed using the simulated chip component 20 and the simulated substrate 40, the positional deviation amount is obtained at all points. It was confirmed that the thickness was 0.5 μm or less.

  With the mounting method according to the present invention, it is possible to easily obtain an offset that has been obtained with trial and error for each production condition so far, and to improve production efficiency. It can be applied to all fields where is required.

DESCRIPTION OF SYMBOLS 1 Flip chip mounting apparatus 2 Chip component 3 Protruding electrode 4 Substrate 5 Electrode 6 Bonding head 7 Substrate holding stage 8 Two-field camera 9 Stage heater 10 Copying mechanism 11 Mount 12 Control unit 20 Simulated chip component 40 Simulated substrate MB Simulated substrate alignment mark MC Simulated chip part alignment mark

Claims (3)

In a mounting method in which the alignment mark of the chip component and the alignment mark of the substrate are recognized by the image recognition means and the chip component and the substrate are aligned and then the chip component is pressurized and mounted on the substrate.
Mounting offset that offsets the amount of misalignment that occurs when chip parts are pressed and mounted after alignment is set as a function of the position within the substrate holding stage that holds the substrate and the pressure applied during bonding .
The mounting method, wherein the function is derived based on a result of obtaining a positional deviation amount with respect to a plurality of conditions of applied pressure at each of a plurality of positions in the substrate holding stage surface . The mounting method according to claim 1 , wherein a transparent chip component on which an alignment mark is written is used when determining a positional shift amount with respect to a plurality of conditions of applied pressure at a plurality of positions in a substrate holding stage surface. Characteristic mounting method. Bonding head for sucking and holding chip components, mechanism for moving the bonding head in the vertical direction, substrate holding stage for placing and holding the substrate, and bonding head and substrate holding stage relatively moving in the horizontal and rotational directions A mounting apparatus having a mechanism and a two-field recognition means provided in a space between the bonding head and the substrate holding stage so as to be able to advance and retreat and capable of simultaneously imaging the head side and the substrate holding stage side;
The mounting apparatus provided with the function to perform the mounting method of Claim 1 or Claim 2 .

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