JP4352999B2 - Part joining method - Google Patents

Description

The present invention relates to parts products joining how to bond the components to the substrate.

  As a method of mounting a bump-equipped electronic component on which a bump, which is a protruding electrode for bonding, such as a flip chip, is mounted on a substrate, a method of bonding the bump to a substrate via a paste such as a resin adhesive is known. In this method, first, a resin adhesive for fixing an electronic component is applied to the surface of the substrate on which the electrode is formed, the suction nozzle holding the electronic component is lowered on the resin adhesive, and the resin adhesive is attached to the electronic component. It is mounted by landing on the board. In this mounting, the bumps are joined to the electrodes of the substrate to be conducted, and the resin adhesive is cured to fix the electronic component main body to the substrate.

In the above electronic component mounting, if the amount of resin adhesive applied earlier is large, a phenomenon occurs in which the resin adhesive wraps around from the side to the top of the electronic component after landing the electronic component on the resin adhesive. There is a case. This phenomenon becomes more prominent as electronic components become thinner. And if the resin adhesive which went around to the upper surface adheres to the lower end part of an adsorption nozzle and hardens | cures, the flatness of the adsorption surface of an adsorption nozzle will be impaired and it will become a factor of joining quality fall. For this reason, there is known an electronic component mounting apparatus provided with a resin adhesion preventing means for preventing resin adhesion by shielding the periphery of the adsorption tool for the purpose of preventing adhesion of the resin adhesive to such an adsorption tool ( For example, see Patent Document 1).
JP 2003-249793 A

  However, in the above-described prior art examples, since shielding parts must be movably disposed around the suction tool, the mechanism is complicated, which contradicts the demand for downsizing of the apparatus and avoids an increase in apparatus cost. hard. Furthermore, it is necessary to periodically remove and clean the shielding parts, which may increase the maintenance load.

Accordingly, the present invention aims at providing a part article joining method that can be prevented adherence of the paste to the suction nozzle.

The component bonding method of the present invention is a component bonding method in which a suction tool holding and holding a component is lowered onto a substrate, and the component is bonded to the substrate by pressing the component against the substrate via a paste, A component holding step of holding the component by the suction tool by sucking inside a suction hole provided in the suction tool, a paste supplying step of supplying a paste to a joint between the substrate and the component, and a substrate mounting portion A positioning step of relatively positioning a component held by the suction tool with respect to the substrate placed on the substrate, and a pressing step of pressing the component against the substrate via a paste, and the adhesion of the pressing step to the suction tool lower surface of the crawl up the paste to the upper surface of the component intended to prevent by boosting the suction hole and said pushing Engineering In, which performs vibration applying for relatively vibrating the component to the substrate, prior to boosting of said suction holes, executes the vibration applying.

  According to the present invention, in the process of pressing the component sucked and held by the suction tool against the substrate, the pressure in the suction hole of the suction tool is increased to rise up to the upper surface of the component and approach the lower surface of the suction tool Can be prevented from adhering to the lower surface of the suction tool.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a component joining apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a control system of the component joining apparatus according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. The figure which shows the joining condition setting screen of the component joining apparatus of this form, FIG. 4, FIG. 5 is process explanatory drawing of the component joining method of one embodiment of this invention.

  First, the configuration of the component joining apparatus will be described with reference to FIG. This component bonding apparatus has a function of bonding an electronic component such as a flip chip having a plurality of bumps on its lower surface to a substrate by pressing load and vibration. Here, a mounting structure that seals the gap between the electronic component and the substrate is a target, and a so-called resin tip that supplies a resin adhesive used as a sealing resin to the substrate in advance before mounting the electronic component. A mounting structure is formed by a coating method. That is, by lowering the suction tool holding and holding the electronic component onto the substrate supplied with the resin adhesive in advance, the electronic component is pressed against the substrate through the resin adhesive, so that the electronic component is attached to the substrate. A mounting method for joining is employed.

  In FIG. 1, a substrate 2 is placed on the substrate platform 1. A resin adhesive 2 a that is a paste for joining electronic components is supplied to the upper surface of the substrate 2. A bonding unit 3 is disposed above the substrate mounting unit 1. The bonding unit 3 includes a lifting / lowering drive unit 4 incorporating a motor and an encoder. The motor of the raising / lowering pressing drive unit 4 is driven by the Z-axis driver 11, whereby the raising / lowering pressing drive unit 4 drives the bonding tool 6 held by the holder 5 up and down. At this time, the rotation amount of the motor is detected by the encoder, and the detection signal is transmitted to the Z-axis driver 11 via the amplifier 10.

  The bonding tool 6 includes a bonding operation portion 6a protruding downward, and a suction hole 6b provided in the bonding tool 6 is opened on the lower surface of the bonding operation portion 6a. The other end of the suction hole 6 b is opened on the upper surface of the bonding tool 6, and the suction hole 6 b is connected to the suction / blow switching valve 12 through a suction pad 6 c in contact with the upper surface of the bonding tool 6. A vacuum suction source 13 and a positive pressure source 14 are connected to the suction / blow switching valve 12. By switching the suction / blow switching valve 12, a vacuum suction operation from the suction hole 6b and a positive pressure to the suction hole 6b are performed. It is possible to switch between the air blowing operation for providing Here, the vacuum suction source 13 and the positive pressure source 14 can arbitrarily set the pressure values of the generated vacuum pressure and the positive pressure, respectively, and can perform the vacuum suction operation and the air blowing operation at an arbitrary pressure. .

  By vacuum suction from the suction hole 6b in a state where the electronic component is in contact with the lower surface of the bonding operation portion 6a, the bonding operation portion 6a holds the electronic component 7 (component) by vacuum suction. Therefore, the bonding operation part 6a is a suction tool for sucking and holding the electronic component 7, and the vacuum suction source 13 is a suction means for sucking the suction hole 6b provided in the suction tool. The bonding tool 6 incorporates heating means such as a constant heater, a pulse heater, and a ceramic heater, and the electronic component 7 held by the bonding action portion 6a is heated by the heating means.

  Further, when the electronic component 7 is sucked and held on the joining portion 6a while being vacuum sucked from the suction hole 6b by the vacuum suction source 13, by switching the suction / blow switching valve 12 to the air blow side, Vacuum suction can be released. At this time, by applying a positive pressure from the positive pressure source 14 to the suction hole 6b, the pressure in the suction hole 6b becomes equal to or higher than the atmospheric pressure corresponding to the applied positive pressure, and air is ejected from the suction hole 6b. Air blow operation is performed. At this time, by stopping the operation of the vacuum suction source 13, it is also possible to cancel the vacuum suction without performing air blow.

  The electronic component 7 is pressed against the substrate 2 via the paste 2a by driving the elevating and pressing drive unit 4 and lowering the bonding tool 6 while holding the electronic component 7 on the bonding operation part 6a. Therefore, the lifting / lowering drive unit 4 is a pressing unit that presses the electronic component 7 held by the suction tool against the substrate 2 placed on the substrate platform 1. At this time, the vibrator 8 mounted on the bonding tool 6 is driven by the US driver 9, so that ultrasonic vibration is applied to the electronic component 7 via the bonding portion 6 a, and the electronic component 7 is applied to the substrate 2. It vibrates relatively. Therefore, the vibrator 8 is a vibration applying unit that applies vibration to the electronic component 7 via the suction tool and vibrates relative to the substrate 2.

  Next, the configuration of the control system will be described with reference to FIG. The load control unit 15 controls the Z-axis driver 11 to control the pressing load when the electronic component 7 is pressed against the substrate 2 by the bonding tool 6. The raising / lowering position control unit 16 controls the height position in the raising / lowering operation of the bonding tool 6 by controlling the Z-axis driver 11. The suction / blow control unit 17 controls the switching operation of the suction / blow switching valve 12. The vibration application control unit 18 controls driving of the vibrator 8 by the US driver 9.

  The pressure state in the suction hole 6b can be changed by switching the suction / blow switching valve 12 by the suction / blow control unit 17 during execution of the component joining operation for joining the electronic component 7 to the substrate 2 by the bonding tool 6. it can. That is, the vacuum suction of the electronic component 7 can be released from the state in which the inside of the suction hole 6b is vacuum-sucked and the electronic component 7 is sucked and held by the bonding portion 6a, and the pressure in the suction hole 6b is increased to increase the pressure. The pressure can also be used to blow out air from the lower surface of the bonding portion 6a and the contact surface of the electronic component 7.

  As described above, in the process of joining the electronic component 7 to the substrate 2 via the resin adhesive 2a by changing the pressure state in the suction hole 6b, the transmission of the ultrasonic vibration is properly performed as described below. It is possible to improve the bonding quality due to the increase in the size, and to prevent problems due to the resin adhesive 2a adhering to the lower surface of the bonding action portion 6a.

  First, by releasing the vacuum suction from the suction hole 6b at the timing when the application of the ultrasonic vibration is continued, the electronic component 7 is released from the suction and holding by the bonding action portion 6a, and the lower surface of the bonding action portion 6a is released. Thus, relative slip in the horizontal direction is allowed. For this reason, a defect that easily occurs when vibration is applied under the condition that the relative slip between the electronic component and the suction tool is constrained, that is, separation occurs at the bonding interface between the bump and the electrode once bonded in the bonding process. It is possible to prevent the occurrence of poor bonding due to.

In the process of pressing the electronic component 7 against the substrate 2, the electronic component 7 tends to sink into the resin adhesive 2 a applied to the substrate 2 as the bumps 7 a are crushed in the vertical direction by the pressing load. It is in. Then, when the resin adhesive 2a that has crawled up to the upper surface of the electronic component 7 due to the sinking of the electronic component 7 is guided to the vacuum suction force by the suction hole 6b and moves to the contact portion between the electronic component 7 and the bonding portion 6a, The resin adhesive 2a is sucked into the gap between the lower surface of the bonding operation portion 6a and the upper surface of the electronic component 7, and adheres to the lower surface of the bonding operation portion 6a. Joining action part 6
When the resin adhesive 2a adhering to the lower surface of a is cured, the bonding action portion 6a does not adhere to the electronic component 7 at the time of adsorption of the electronic component 7 and hinders normal adsorption and retention. Therefore, the bonding action portion of the resin adhesive 2a It is necessary to prevent adhesion to 6a as much as possible.

  Here, as described above, when a positive pressure is applied to the suction hole 6b in the pressing process of the electronic component 7 by the bonding tool 6, air is ejected from the gap between the contact surfaces of the electronic component 7 and the bonding action portion 6a. To do. Thereby, the approach to the joining action part 6a of the resin adhesive 2a scooped up on the upper surface of the electronic component 7 is blocked by the jetting air, and the adhesion of the resin adhesive 2a to the joining action part 6a is prevented. Accordingly, in the configuration of the component joining apparatus shown in FIGS. 1 and 2, the suction / blow switching valve 12, the positive pressure source 14, and the suction / blow control unit 17 are electronic components held by the joining operation unit 6a which is a suction tool. In the component pressing step of pressing the substrate 7 against the substrate 2, the paste that prevents the adhesion of the resin adhesive 2a that has crawled up to the upper surface of the electronic component 7 to the lower surface of the bonding portion 6a by increasing the pressure inside the suction hole 6b. It is an adhesion prevention means.

  In order to prevent the resin adhesive 2a from adhering to the bonding portion 6a, it is not always necessary to apply a positive pressure to the suction hole 6b to blow out air, and the vacuum suction in the suction hole 6b is released. In some cases, it is sufficient to do. That is, the supply amount of the resin adhesive 2a applied to the substrate 2, the physical properties of the resin adhesive 2a, the distance until the resin adhesive 2a reaches the bonding portion 6a on the upper surface of the electronic component 7, and the component pressing time, etc. Depending on various conditions, it may be possible to prevent adhesion to the bonding portion 6a simply by releasing the vacuum suction and eliminating the vacuum suction force acting on the resin adhesive 2a. In this case, the suction / blow switching valve 12 and the suction / blow control unit 17 serve as the paste adhesion preventing means.

  The calculation unit 20 is a CPU, and executes various processing operations by executing a program stored in the storage unit 21. In addition to the above-described program, the storage unit 21 stores data necessary for the electronic component joining operation such as a joining condition parameter described below. The joining condition setting unit 22 sets joining condition parameters when joining the electronic component 7 to the substrate 2. Here, the magnitude and timing of the pressing load when the electronic component 7 is pressed against the substrate 2 by the bonding tool 6, and the ultrasonic output and application when applying ultrasonic vibration via the bonding tool 6 by the vibrator 8. The parameters indicating the timing, the suction / blow timing by the vacuum suction source 13 and the positive pressure source 14 are set by the load setting unit 22a, the US output setting unit 22b, and the suction / blow setting unit 22c, respectively.

  The operation / input unit 23 is input means such as a keyboard and a mouse, and performs operation command input and various data input operations. The display unit 24 is a display panel, and displays a guidance screen at the time of input operation by the operation / input unit 23. The joining condition setting by the joining condition setting unit 22 can be executed by inputting data from the operation / input unit 23 on the condition setting screen displayed on the display unit 24.

  The joining condition setting screen will be described with reference to FIG. FIG. 3 shows a joining condition setting screen displayed on the display screen 24 a of the display unit 24 in the joining condition setting by the joining condition setting unit 22. On the joining condition setting screen, time charts of operations of pressing, applying ultrasonic vibration, and suction / blowing are displayed with the time axis (horizontal axis) matched. Then, by inputting necessary items such as a load value, ultrasonic output, and timing through the operation / input unit 23 on the display screen 24a, the joining condition is set.

Therefore, the joining condition setting screen is a timing setting screen for setting the timing for causing the pressing means, the vibration applying means, and the suction releasing means to function. The joining condition setting unit 22 and the operation / input unit 23 include the pressing means, the vibration applying means, and the vibration applying means. It is a timing setting means for setting the timing at which the suction releasing means functions on the timing setting screen displayed on the display means.
By providing such a timing setting means, it is possible to display the operation timings of pressing, applying ultrasonic vibration, and suction / blowing with a good list on the same screen. Therefore, it is possible to perform the joining condition setting work with good operability while clearly grasping the relationship between the operations.

  A specific example of setting the joining conditions will be described with reference to FIG. In this example, first, the pressing load applied by the elevation pressing drive unit 4 is changed in three stages. That is, the load value increases from the timing t0 when the bonding tool 6 is lowered and the electronic component 7 is landed on the substrate 2 and pressing is started to P1, and the load value is increased from the timing t1 when the load value reaches P1 to the timing t2. Is held at P1. At time t2, the load value increases to P2, and this load value P2 is held until time t3. Thereafter, the load value decreases to P3 smaller than P1, and the load value is held at P3 until the timing t4 when the joining is completed.

  Next, application of ultrasonic vibration will be described. After the electronic component 7 has landed, driving of the vibrator 8 is started with the ultrasonic output W1 at the timing t5 set between the timings t1 and t2, and this output is maintained until the timing t6 earlier than the timing t3. It is. Then, the application of ultrasonic vibration is continued while gradually decreasing the ultrasonic output, and the application of vibration is stopped at timing t7 set between timings t3 and t4.

  Next, the suction / blow operation will be described. In order to hold the electronic component 7 on the bonding tool 6, the electronic component 7 is in the state of being sucked and held by the bonding operation portion 6 a before landing on the substrate 2, and the vacuum suction source 13 is also after timing t 0 when the bonding operation is started. The suction by is continued. At a timing t8 set between timings t5 and t6, the suction / blow switching valve 12 is switched to switch to a blowing operation for applying a positive pressure to the suction hole 6b. Thereafter, the blowing operation is continued until timing t9 which is later than timing t4.

  Based on the bonding conditions set as described above, the component bonding method executed using the component bonding apparatus shown in FIG. 1, that is, the bonding operation portion 6a holding the electronic component 7 by suction is lowered onto the substrate 2, A component bonding method for bonding the electronic component 7 to the substrate 2 by pressing the electronic component 7 against the substrate 2 via the resin adhesive 2a will be described with reference to FIGS.

  First, as shown in FIG. 4A, an electronic component 7 having bumps 7a formed on the lower surface by sucking (see arrow a) the inside of the suction hole 6b provided in the bonding portion 6a, which is a suction tool. Is held by the joining action portion 6a (part holding step). At this time, the electronic component 7 is heated by the heating means built in the bonding tool 6. Then, as shown in FIG. 4B, a resin adhesive 2a, which is a paste, is supplied to a joint portion with the electronic component 7 on the upper surface of the substrate 2 (paste supply process). Note that either the component holding step or the paste supplying step may be performed first.

  Next, as shown in FIG. 4C, the bonding tool 6 is moved so that the electronic component 7 held by the bonding action portion 6a is positioned relative to the substrate 2 placed on the substrate placement portion 1. Align (alignment process). Then, as shown in FIG. 4 (d), the bonding tool 6 is lowered by the elevation pressing drive unit 4, and the electronic component 7 is pressed against the substrate 2 via the resin adhesive 2a (pressing step). In this pressing step, first, the electronic component 7 is pressed against the substrate 2 by the bonding tool 6 with the first pressing load P1. Thereby, the lower surfaces of the bumps of the electronic component 7 come into contact with the surface of the substrate 2. In the pressing step, the resin adhesive 2a is heated via the electronic component 7 to promote the thermosetting reaction of the resin adhesive 2a.

Then, at timing t5 shown in FIG. 3, as shown in FIG. 5A, vibration is applied to the substrate 2 to vibrate the electronic component 7 relatively (see arrow b). At this time, ultrasonic vibration is first applied at the output W1, and then the pressing load is increased to the second pressing load P2 at timing t2. Thereby, metal bonding proceeds at the bonding interface between the lower surface of the bump and the surface of the electrode 2a, and the fixing strength gradually increases. During this time, the vacuum suction from the suction hole 6b is continuously performed, and the electronic component 7 is held by suction to the bonding portion 6a. For this reason, the ultrasonic vibration imparted to the bonding tool 6 by the vibrator 8 is satisfactorily transmitted to the electronic component 7 via the bonding action portion 6a.

  In the pressing step, the bump 7a is crushed in the vertical direction by the pressing load, so that the electronic component 7 sinks into the resin adhesive 2a. Then, the resin adhesive 2a reaches the upper surface of the electronic component 7 by this sinking. At this time, since vacuum suction from the bonding tool 6 is continued, vacuum suction is performed from the gap between the bonding portion 6a and the upper surface of the electronic component 7 (see arrow c), and the resin adhesive 2a is vacuum-sucked. It tends to move toward the abutting portion between the electronic component 7 and the bonding operation portion 6a by being guided by the force.

  Thereafter, at timing t8 when application of ultrasonic vibration is continued, as shown in FIG. 5B, the vacuum suction from the suction hole 6b is switched to air blow (see arrow d). Then, when the pressure in the suction hole 6b is increased to exceed the atmospheric pressure, air is diffused to the periphery from the gap between the lower surface of the bonding operation portion 6a and the electronic component 7 (see arrow e). As a result, the resin adhesive 2a that has once reached the upper surface of the electronic component 7 is removed outward by the air diffused to the periphery, and is prevented from approaching the lower surface of the bonding operation portion 6a. That is, the adhesion of the resin adhesive 2a that crawls up to the upper surface of the electronic component 7 to the lower surface of the bonding portion 6a is prevented by increasing the pressure in the suction hole 6b.

  In this pressing step, air at normal temperature is not sucked from the suction hole 6b after the timing t8, and the resin adhesive 2a can be efficiently heated through the electronic component 7. Thereafter, by raising the bonding tool 6, as shown in FIG. 5C, the bonding action portion 6 a is separated from the electronic component 7 bonded on the substrate 2 via the resin adhesive 2 a, and one electronic component The component joining operation for 7 is completed.

  In the above-described component joining operation, the suction / blow switching valve 12 is switched to apply a positive pressure to the suction hole 6b at a timing t8 that is later than the timing t5 at which vibration application is started, and the pressure in the suction hole 6b is increased. The vibration is applied in advance. Thereby, since the application of vibration is started in a state where the electronic component 7 is attracted and held on the bonding operation portion 6a, vibration energy for bonding the bump 7a can be efficiently transmitted.

  Then, even after the vacuum suction is released and the blow operation is started at the timing t8, the application of vibration to the electronic component 7 is continued. At this time, the suction surface on the lower surface of the bonding action portion 6a is deformed so as to be slightly undulated by vibration, and a gap is formed between the upper surface of the electronic component 7 and the suction surface. Since air is diffused to the surroundings by air blow from the hole 6b, the adhesion of the resin adhesive 2a to the bonding action portion 6a is prevented.

  Note that the determination of the timing t8 in the time chart of FIG. 3 is to prevent the adhesion of the resin adhesive 2a to the lower surface of the bonding operation portion 6a as described above, and to ensure good vibration transmission efficiency in the initial stage of the component bonding process. To be decided in consideration of the viewpoint of That is, in order to surely prevent the adhesion of the resin adhesive 2a, it is desirable to start the blowing operation early to eliminate the arrival of the resin adhesive 2a to the upper surface of the electronic component 7, but to improve the vibration transmission efficiency. For this reason, it is desirable that the electronic component 7 is held by suction at the bonding operation portion 6a at least for a predetermined time from the vibration application start time.

  For this reason, when determining the timing t8, the vibration application time required to advance the bonding of the bumps 7a to a desired level under the condition in which the electronic component 7 is attracted and held is obtained in advance by trial, and the obtained predetermined time is obtained. The time when the vibration applying time has elapsed is set as the timing t8. With this timing setting, in the pressing process, after the predetermined vibration application time has elapsed, the pressure increase in the suction hole 6b is started, and any request of improving the ultrasonic bonding efficiency and preventing the adhesion of the resin adhesive 2a is performed. As a result, a bonding condition that substantially satisfies the above conditions is realized.

  In the above embodiment, an example of using a resin adhesive functioning as a sealing resin as a paste is shown, but the present invention is not limited to a resin adhesive, and an electronic component is bonded to a substrate. Any viscous fluid that is preliminarily applied to the substrate during the mounting process is applicable to the present invention.

Substrate parts products bonding method of the present invention has the effect that it is possible to prevent adhesion of crawl up to the upper surface of the part to the suction tool lower surface of the paste to approach the lower surface of the suction tool, the part via a paste It can be used in the field of mounting by pressing the

The front view of the component joining apparatus of one embodiment of this invention The block diagram which shows the structure of the control system of the component joining apparatus of one embodiment of this invention The figure which shows the joining condition setting screen of the component joining apparatus of one embodiment of this invention Process explanatory drawing of the component joining method of one embodiment of this invention Process explanatory drawing of the component joining method of one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate mounting part 2 Board | substrate 2a Resin adhesive 4 Lifting / lowering drive part 6 Bonding tool 6a Joining action part 7 Electronic component 8 Vibrator

Claims (3)

A component bonding method for bonding a component to a substrate by lowering the suction tool holding the component onto the substrate and pressing the component against the substrate via a paste, the suction tool provided on the suction tool A component holding step of holding the component by a suction tool by sucking the inside of the hole, a paste supplying step of supplying a paste to a joint portion between the substrate and the component, and a substrate mounted on the substrate mounting portion An alignment step of relatively aligning the component held by the suction tool, and a pressing step of pressing the component against the substrate through a paste, up to the upper surface of the component in the pressing step The adhesion of the soaking paste to the lower surface of the suction tool is prevented by increasing the pressure in the suction hole. And performs a vibration applying for relatively vibrating the parts, prior to boosting of said suction holes, parts products joining how to and executes the vibration applying. Component bonding method according to claim 1, characterized in that also continue running continuously the vibration applying the after starting the boosting operation. Wherein in the pressing step, component bonding method according to claim 1, wherein the initiating boosting of said suction holes after the predetermined vibration application time has elapsed.

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