JP2012069742A - Mounting method and mounting apparatus for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check displacement including rotational deviation, that is twist, of electronic components in a plane vertical to a mounting direction before bonding.SOLUTION: A mounting method comprises the steps of: holding an electronic component 22 having ball-shaped bumps 25 on a surface thereof, in a placing head 20; displacing the placing head toward a mounting board while positioning of both the electronic component and the mounting board are conducted so as to press the bumps onto electrodes formed on a mounting surface of the mounting board; and bonding the bumps thereto by fusing the bumps in a state of pressure contact. When the electronic component held in the placing head is positioned and applied pressure contact against the mounting board, the placing head is subjected to two loads in a same direction, which are generated in a plane vertical to a mounting direction, and the two loads are measured by load measuring means S arranged at two separate points in the vertical plane so that displacement of the bump and the electrode are detected.

Description

  The present invention relates to a mounting method and apparatus for flip-chip mounting an electronic component (such as a semiconductor chip) on a mounting substrate.

  Flip chip mounting is known as one method for mounting electronic components on a mounting substrate. Flip chip mounting is a method of connecting electrodes on a mounting substrate and chip bump portions by forming metal protrusions called bumps on electrode pads on the surface of a semiconductor chip and flipping the chip.

  By the way, in flip chip mounting, since the electrode pads on the chip surface are directly connected to the electrodes on the mounting substrate via bumps formed on the mounting surface of the semiconductor chip, the connection portion cannot be recognized from the outside. Therefore, the inspection of the chip mounting position deviation is generally performed using a dedicated inspection machine after mounting on the mounting substrate. Accordingly, even if a misalignment defective product is detected, it has already been joined, and the defective electronic component must be discarded as it is. In addition, in the case of misalignment due to a trouble with the mounting machine, there is a time lag from mounting to inspection, and there is a risk of continuously making defective products during that time. Therefore, a method for detecting a positional deviation immediately after the positional deviation occurs is expected.

  As a method for inspecting the mounting position in the mounting method in which the electronic component is connected to the mounting surface of the mounting substrate via the bump, the connection portion between the bump of the electronic component and the electrode of the mounting substrate cannot be easily recognized. The method of checking the transmission image from above or below the electronic component with a machine, the method of directly recognizing the bump and electrode from the side of the mounted electronic component, instead of recognizing the bump and electrode, the positioning mark of the mounting board and the electronic component There is a method of estimating the positional deviation between the bump and the electrode by recognizing the outer shape.

  However, the method of recognizing misalignment with an X-ray inspection machine requires an expensive X-ray inspection apparatus, which increases the cost of the product. Further, since the inspection time is longer than the mounting time, productivity is lowered. Therefore, in many cases, it must be a sampling inspection.

  In addition, the method of recognizing the bonding state from the side surface of the mounted electronic component requires a space for arranging the observation optical system around the electronic component, and there is a problem that the mounting density around the electronic component is reduced. Further, since confirmation is performed from four directions, it takes an inspection time longer than the mounting time, and in many cases, a sampling inspection is unavoidable as in the case of using an X-ray inspection machine.

  In addition, instead of recognizing bumps and electrodes, the method of estimating the displacement of bumps and electrodes by recognizing the positioning marks on the mounting board and the external shape of the electronic component is based on the measured amount of displacement between the bumps and electrodes. Due to the dicing accuracy of electronic components, measurement errors increase in the measurement of positional deviations between bumps and electrodes, which are increasingly miniaturized.

  Further, since the above three methods perform inspection after mounting and joining, even if a misalignment is found, the electronic component must be discarded. In addition, there is a time lag from the mounting joining process to the misalignment inspection process, and even if misalignment due to the trouble of the mounting machine occurs, the discovery of the trouble is delayed, and during that time, it continues to produce defective products There is also.

  On the other hand, as a technique capable of solving the problems of the inspection method described above, Patent Document 1 discloses a substrate holding unit that holds a substrate, a holding head that holds an electronic component, and a holding head or a substrate holding unit. A load sensor having two piezoelectric elements that generate a voltage in response to a horizontal load in two directions substantially perpendicular to the mounting direction of the electronic component and substantially perpendicular to each other, and the load sensor detects the load sensor. A mounting abnormality detection that detects a mounting abnormality of an electronic component by comparing a position in a two-dimensional space having a horizontal load value in two directions as a coordinate value and a preset allowable range in the two-dimensional space. And an electronic component mounting apparatus including a unit.

Japanese Patent Laid-Open No. 2005-19956

  According to the electronic component mounting apparatus described in Patent Literature 1, for example, two directions (X direction) that act on the holding head (mounting head) and are substantially perpendicular to the mounting direction (Z direction) of the electronic component and substantially orthogonal to each other. Since the horizontal load in the Y and Y directions can be measured, it is also possible to detect the positional deviation in the X and Y directions between the bumps on the surface of the electronic component and the electrodes on the mounting board from the horizontal load data. It appears to be.

  However, actual positional deviation between the bump and the electrode may include positional deviation (twist) in the rotation direction in addition to positional deviation in the X direction and positional deviation in the Y direction. Even with this technique, it has been found that there is a problem that even such positional deviation in the rotational direction cannot be detected.

  In view of the above circumstances, an object of the present invention is to provide an electronic component mounting method and apparatus capable of inspecting positional displacement in a plane perpendicular to the mounting direction of the electronic component, including torsion, before joining. .

  In order to solve the above-described problems, an electronic component mounting method according to the present invention includes an electronic component in which ball-shaped bumps are respectively formed on a plurality of electrode pads arranged on the surface, and the surface on which the bumps are formed is a mounting substrate. The mounting head is formed on the mounting surface of the mounting substrate by displacing the mounting head toward the mounting substrate while positioning the electronic component and the mounting substrate relative to each other. A step of pressing and contacting the bump to the electrode, and a step of electrically bonding the electronic component and the mounting substrate via the bump by melting the bump in a pressed contact state, When the electronic components held on the mounting head are brought into pressure contact with the mounting substrate while being positioned, two of the same directions generated in a plane perpendicular to the mounting direction applied to the mounting head A load, by measuring in mutually spaced two places in the plane perpendicular to and detects the positional deviation between the bump and the electrode.

  In the electronic component mounting apparatus according to the present invention, an electronic component in which ball-like bumps are respectively formed on a plurality of electrode pads arranged on the surface is arranged such that the surface on which the bumps are formed faces the mounting surface of the mounting substrate. Mounting bumps, means for positioning the electronic component and the mounting board relative to each other, and displacing the mounting head toward the mounting board, thereby applying the bumps to the electrodes formed on the mounting surface of the mounting board. A means for pressing contact, a means for electrically joining the electronic component and the mounting substrate via the bump by melting the bump in a pressure contact state, and an electronic component held on the mounting head are mounted. Two loads in the same direction generated in a plane perpendicular to the mounting direction applied to the mounting head when pressed against the substrate while being positioned are applied in the vertical plane. Characterized in that it comprises a and a load measuring means for measuring at two points spaced are.

  According to the electronic component mounting method and apparatus according to the present invention, the positional deviation between the bump on the surface of the electronic component and the electrode of the mounting substrate is detected at the stage of applying pressure before the electronic component is bonded to the mounting substrate. be able to. For this reason, even when a positional deviation is detected, it is possible to re-mount the electronic component that has been misaligned, thereby reducing the number of defects. In addition, since the positional deviation can be detected immediately at the moment when the positional deviation occurs, it is possible to avoid the continuous production of defective products due to a trouble with the mounting machine. In addition, since two loads in the same direction are detected at two locations separated from each other, a plane perpendicular to the mounting direction of the bumps on the surface of the electronic component and the electrodes on the mounting board is used by utilizing the difference between the two load detection values. It is possible to detect the torsion (θ) inside.

It is a perspective view which shows the principal part schematic structure of the mounting device of the electronic component of embodiment of this invention. It is principal part sectional drawing of the same mounting apparatus. It is an AA arrow line view of FIG. It is operation | movement explanatory drawing of the apparatus, and is principal part sectional drawing which shows the case where there exists a position shift of a X direction between a bump and an electrode. It is operation | movement explanatory drawing of the apparatus, and is principal part sectional drawing which shows the case where there is no position shift between a bump and an electrode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of a main part of a mounting apparatus according to the embodiment, FIG. 2 is a cross-sectional view of the main part of the apparatus, and FIG. 4 and 5 are explanatory views of the operation of the apparatus. FIG. 4 is a cross-sectional view of the main part showing a case where there is a positional deviation in the X direction between the bump and the electrode, and FIG.

  In this mounting apparatus, as shown in FIGS. 1 to 3, ball-shaped bumps 25 are respectively formed on a substrate stage 10 for fixing the mounting substrate 11 and a plurality of electrode pads (not shown) arranged on the surface. The mounting nozzle 21 that holds the electronic component 22 so that the surface on which the bumps 25 are formed faces the mounting surface of the mounting substrate 11, the mounting head 20 in contact with the upper surface of the mounting nozzle 21, and the mounting nozzle 21 on the mounting head 20. A compression spring 23 that presses against the mounting nozzle contact surface and presses the mounting nozzle 21 toward the center of the mounting head 20; and a mounting head moving mechanism (not shown) that moves the mounting head 20 toward and away from the substrate stage 10. And positioning means (not shown) for positioning the mounting substrate in a direction parallel to the mounting surface with respect to the electronic component. Here, the mounting head moving mechanism corresponds to means for pressing the bumps 25 against the electrodes 15 formed on the mounting surface of the mounting substrate 11 by displacing the mounting head 20 toward the mounting substrate 11.

  The mounting apparatus further includes means (not shown) for electrically joining the electronic component 22 and the mounting substrate 11 via the bumps 25 by melting the bumps 25 in a pressure contact state. When the electronic component 22 held by the mounting head 20 is pressed and contacted with the mounting substrate 11 while being positioned, they are perpendicular to each other and generated in a plane perpendicular to the mounting direction (Z direction) applied to the mounting head 20. Load measuring means S for measuring each load in the first direction (X direction) and the second direction (Y direction). In this case, the load measuring means S for measuring the load in one direction of the first direction (X direction) and the second direction (Y direction) are arranged at two positions separated from each other in the other direction. Has been.

  The load measuring means S measures the force generated in the direction perpendicular to the mounting direction (Z direction) applied to the mounting nozzle 21 via the compression spring 23, one in the X direction and an appropriate interval in the Y direction. A total of two is provided with a gap of two, and one load measuring means Sx in the X direction detects a force in the X direction applied to the mounting head 20, and two load measuring means Sy1 in the Y direction. , Sy2 detects the force in the Y direction applied to the mounting head 20 at two locations separated in the X direction. Therefore, it is possible to detect the force in the θ direction that is the rotational direction. Note that one load measuring means S may be arranged in the Y direction and two at an appropriate interval in the X direction.

Next, an electronic component mounting method will be described with reference to FIGS.
First, an electronic component 22 in which ball-like bumps 25 are respectively formed on a plurality of electrode pads (not shown) arranged on the package surface is mounted so that the surface on which the bumps 25 are formed faces the mounting surface of the mounting substrate 11. The nozzle 21 adsorbs and holds it on the mounting head 20. Next, the mounting substrate 11 is positioned in a direction parallel to the mounting surface by the positioning means so that the positions of the bumps 25 of the electronic component 22 and the electrodes of the mounting substrate 11 coincide.

  Next, the mounting head 20 is moved in the direction of the substrate stage 10 by the mounting head moving mechanism, and the bumps 25 of the electronic component 22 and the electrodes 15 of the mounting substrate 11 are pressed and brought into pressure contact with each other. At this time, as shown in FIG. 4, when the bump 25 on the electronic component 22 side is displaced with respect to the electrode 15 of the mounting substrate 11, the reaction force r of the distributed load f of the applied pressure F applied to the mounting head 20 is In the contact position between the electrode 15 and the bump 25, the force rz in the vertical direction (Z direction) and the force rx (ry is not shown) in the horizontal direction (X direction and Y direction) are disassembled. The sum of horizontal forces generated at the contact position between the bump 25 and the electrode 15 is loaded.

  Since the mounting nozzle 21 has a degree of freedom in the horizontal direction with respect to the mounting head 20 via the compression spring 23, the mounting nozzle 21 moves relative to the mounting head 20 by the force applied to the mounting nozzle 21 ( The amount of movement is a value obtained by dividing the force applied to the mounting nozzle 21 by the spring constant of the compression spring 23), and the compression spring 23 is deformed. Then, the force applied to the mounting nozzle 21 due to the deformation of the compression spring 23 is measured by the load measuring means S.

  For example, when the electronic component 22 is displaced in the X direction with respect to the mounting substrate 11, a force in the X direction is applied to the mounting nozzle 21, and the magnitude of the force is a load measurement arranged in the X direction. It is detected by means Sx. Further, when the electronic component 22 is displaced in the Y direction with respect to the mounting substrate 11, a force in the Y direction is applied to the mounting nozzle 21, and the magnitude of the force is two in the Y direction. This is the sum of the values detected by the load measuring means Sy1, Sy2.

  Further, when the electronic component 22 is displaced in the θ direction (rotation direction) with respect to the mounting substrate 11, a force in the θ direction is applied to the mounting nozzle 21, and the magnitude of the force is arranged in the Y direction. This is the difference between the values detected by the two load measuring means Sy1 and Sy2.

  Further, the amount of deviation in each direction and the magnitude of the force in each direction applied to the mounting nozzle 21 detected by each load measuring means Sx, Sy1, Sy2 have a correlation, and the amount of deviation and the mounting nozzle 21 in advance are correlated. In the process of mounting the electronic component 22 on the mounting substrate 11 by acquiring the correlation data of the relationship of the force applied to the load, each load measuring means when the bump 25 of the electronic component 22 and the electrode 15 of the mounting substrate 11 come into contact with each other. When the measured value of S (Sx, Sy1, Sy2) is observed, and the force applied to the mounting nozzle 21 is detected, the displacement direction and position of the mounting substrate 11 and the electronic component 22 are determined from the direction and magnitude of the force. The amount of deviation is calculated, the mounting head 20 is raised while holding the electronic component 22, the position deviation amount in each direction (X, Y, θ) is corrected by the positioning stage, and the mounting head 20 is lowered again. , Mounting the electronic component 22 on the mounting substrate 11. Thereafter, the measurement value of the load force detection means S is observed again, and if the force applied to the mounting nozzle 21 is not detected, the electronic component 22 is accurately mounted on the mounting substrate 11 and the mounting process is completed. To do.

  When there is no positional deviation between the bump 25 and the electrode 15, as shown in FIG. 5, the distributed load f of the applied force F applied to the mounting head and the reaction force r are balanced in the mounting direction (Z direction). As a result, all the distributed loads f are transmitted to the substrate stage 10, and no force is generated in the mounting head 20 in the direction perpendicular to the mounting direction. Therefore, the load measuring means S does not detect any force.

  As described above, according to the mounting apparatus and method of the present embodiment, the bump 25 on the surface of the electronic component 22 and the electrode of the mounting substrate 11 are applied at the stage of pressurization before the electronic component 22 is bonded to the mounting substrate 11. 15 can be detected. For this reason, even when a positional shift is detected, the electronic component 22 that has been shifted can be mounted again, and the loss of work can be reduced. In addition, since the positional deviation can be detected immediately at the moment when the positional deviation occurs, it is possible to avoid the continuous production of defective products due to a trouble with the mounting machine.

  In addition, since two loads in the same direction are detected at two locations separated from each other, the mounting direction of the bumps 25 on the surface of the electronic component 22 and the electrodes 15 on the mounting substrate 11 is made using the difference between the two load detection values. Torsion (θ) in a plane perpendicular to the axis can be detected.

11 Mounting board 15 Electrode 20 Mounting head 22 Electronic component 25 Bump S Load measuring means

Claims (4)

A step of holding an electronic component in which a ball-shaped bump is formed on each of a plurality of electrode pads arranged on the surface on a mounting head so that a surface on which the bump is formed faces a mounting surface of the mounting substrate;
While pressing the electronic component and the mounting substrate relative to each other, by displacing the mounting head toward the mounting substrate, pressurizing the bumps to the electrodes formed on the mounting surface of the mounting substrate; and
A step of electrically bonding the electronic component and the mounting substrate via the bump by melting the bump in a pressure contact state;
With
When the electronic component held by the mounting head is brought into pressure contact with the mounting substrate while being positioned, two loads generated in a plane perpendicular to the mounting direction applied to the mounting head are the same. A method of mounting an electronic component, wherein a positional deviation between the bump and the electrode is detected by measuring at two positions separated from each other in the vertical plane.   A first direction perpendicular to each other generated in a plane perpendicular to the mounting direction applied to the mounting head when the electronic component held by the mounting head is brought into pressure contact with the mounting substrate while being positioned; By measuring each load in the second direction, and by measuring the load in one direction of the first direction and the second direction at two locations separated from each other in the other direction, The electronic component mounting method according to claim 1, wherein a positional deviation between the bump and the electrode is detected. A mounting head for holding electronic components each having a ball-shaped bump formed on each of a plurality of electrode pads arranged on the surface so that the surface on which the bump is formed faces the mounting surface of the mounting substrate;
Means for positioning the electronic component and the mounting substrate relative to each other;
Means for pressing and contacting the bumps to the electrodes formed on the mounting surface of the mounting substrate by displacing the mounting head toward the mounting substrate;
Means for electrically bonding the electronic component and the mounting substrate via the bumps by melting the bumps in a pressure contact state;
When the electronic component held by the mounting head is brought into pressure contact with the mounting substrate while being positioned, two loads generated in a plane perpendicular to the mounting direction applied to the mounting head are the same. Load measuring means for measuring at two points spaced apart from each other in the vertical plane;
An electronic component mounting apparatus comprising:   A first direction and a first direction perpendicular to each other generated in a plane perpendicular to the mounting direction applied to the mounting head when the electronic component held by the mounting head is brought into pressure contact with the mounting substrate while being positioned. Load measuring means for measuring each load in the two directions, and the load measuring means for measuring the load in one of the first direction and the second direction is in either one of the directions. 4. The electronic component mounting apparatus according to claim 3, wherein the electronic component mounting apparatus is disposed at two positions spaced apart from each other.

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