JP4745073B2 - Manufacturing method of surface mounted light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method which enables flip chip bonding short in assembly time while keeping high luminance characteristic with a light emitting device easy in acquisition. <P>SOLUTION: The method of manufacturing the surface-mounted light emitting device includes the steps of: accepting a wafer in which a light emitting element chip group already processed in dicing is stuck in a face-up state on an expanded tape; forming a stud bump in a pad of the light emitting element chip; and arranging the light emitting element chip group with the stud bump formed on a first adhesion tape in a face-down state. The flip chip bonding is processed by picking up the light emitting element chip arranged on the adhesion tape in the face-down state, and by arranging it in a substrate. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a surface-mounted light emitting device, and more particularly, to a method for manufacturing a flip-chip mounted type light emitting diode.

Light emitting elements such as light emitting diodes (hereinafter abbreviated as LEDs) are required to have high brightness and high heat dissipation.
4 and 5 are diagrams illustrating examples of the surface mount type light emitting element 98. FIG. 4 is a cross-sectional view of the wire bonding mounting type surface mount type LED, and FIG. 5 is a cross sectional view of the flip chip mounting type surface mount type LED. Show.
In the wire bonding mounting type surface mounting type LED 98 shown in FIG. 4, the LED chip 76 is mounted face up on the electrode 72 of the substrate 70, and the pad on the upper surface of the chip and the electrode 74 are conductive wires such as gold wires. 78 are connected by a wire bonding method. The lower surface of the LED chip 76 and the pads on the upper surface of the chip are the anode electrode or cathode electrode of the LED, respectively. The LED chip 76 and the conducting wire 78 are sealed and protected with a resin 80.
Such a surface mount type LED can be stably produced because it uses a proven technology called wire bonding, but the light emitted upward in FIG. However, it is difficult to achieve high heat dissipation due to the structure.
In the following drawings, the same members are denoted by the same numbers.

Therefore, flip chip mounting of LED chips is desired.
In the flip chip mounting type surface mounting type LED 98 shown in FIG. 5, an LED chip 88 is mounted face down on the electrodes 84 and 86 of the glass epoxy substrate 82, and the pads on the lower surface of the chip and the electrodes 84 and 86 are arranged. Are connected by a bump 90 by a flip chip method. The two bumps 90 of the LED chip 88 are the anode electrode or cathode electrode of the LED, respectively. The LED chip 88 and the bump 90 are sealed and protected with a resin 92.

Such a flip-chip mounting type surface mounting type LED has a problem of how to form bumps.
As described in Patent Document 1, when solder bumps are used, there is a concern that the characteristics of the LED element deteriorate due to the influence of flux. That is, a problem occurs in increasing the brightness. In addition, when an attempt is made to join the LED chip and the substrate by gold-gold ultrasonic bonding using gold bumps and gold electrodes on the substrate using gold bumps, the mounting time increases. In addition, high accuracy is required for placing the LED chip on the substrate. Therefore, it is preferable to place the gold bump product on a substrate on which gold-tin solder having a high melting point, for example, is printed and to join them by a reflow method.

However, even when gold bump products are bonded by the reflow method, a considerably long mounting time is required when the process is examined.
FIG. 6 is a diagram showing a conventional process in a case where a gold bump product is flip-chip connected by a reflow method. For the sake of simplification, the description of the process in FIG. 6 is held until just before the LED chip is placed on the substrate.
6A is a view showing the form of the LED chip received in the wafer receiving process. The LED chip 52 is face-up on the expanded tape 50, that is, the chip pad 54 is the opposite surface of the expanded tape 50. It is pasted to become.
In (b), the LED chip 52 is remounted on a rigid substrate 51 that enables wire bonding, and the LED chip 52 is fixed to the substrate 51 with a resin 56. However, the fixation to the rigid substrate 51 for putting the stud bump into a state requires a long time of 2 hours for curing the adhesive, which is a fixing resin, because there is no adhesive that can be temporarily fixed and easily peeled off. .

(C) is the figure which formed the gold bump 58 in the LED chip 52, and this gold bump is what is called a stud bump formed by the apparatus similar to a wire bonder.
(D) is the figure which showed the process of wash | cleaning LED chip 52 with apparatuses, such as beaker 60, for example, after forming stud bump 58, LED chip was peeled off from the board | substrate 51, and resin 56 fixed to the board | substrate 51 was LED chip. 52 is removed by washing. This process is important because the resin remaining after washing blocks the light emitted from the LED chip 52 and lowers the luminance.

  (E) is the figure which showed the state which rearranged and mounted the LED chip 52 on the adhesive tape 62, and since the LED chip 52 will fall apart in the washing | cleaning process shown in (d), it is re-in this way. It takes a long time to arrange. The LED chip group rearranged through the cleaning process after the formation of the stud bump as shown in (e) is placed in a face-down state on a collective substrate on which solder is printed by, for example, a flip chip bonder, and reflowed. Soldered in a furnace. The aggregate substrate is a substrate in which a large number of substrates corresponding to the substrate 82 shown in FIG.

  Conventionally, flip-chip mounting of light-emitting elements such as LEDs has been performed in such a process. However, LED chips are fixed to a rigid substrate, chips are rearranged after a cleaning process, and LED chips are mounted on a collective substrate. It took a lot of time to set up. The latter two processes take time as the number of chips per wafer increases, and it is difficult to shorten the assembly time required for flip chip mounting while maintaining high luminance.

As for a manufacturing method for flip-chip mounting a single chip cut from a wafer, there are many proposals as described in Patent Document 2, for example. Most of these manufacturing methods are based on the premise that bumps are formed in a wafer state.
However, in general, LED wafers are generally supplied with bumps not formed and scribed and chopped into small pieces. Special specification wafers such as bump-formed wafers are provided unless there are special conditions. It is not available. Therefore, in the past, it took a long assembly time to try flip chip mounting while maintaining high luminance.

JP2003-304003 JP-A-2005-332896

  The problem to be solved is to realize a manufacturing method that enables easy flip chip mounting with a short assembly time while maintaining high luminance characteristics with a readily available light emitting element.

The method for producing a surface-mounted light-emitting device of the present invention includes a transfer step of rearranging the diced light-emitting device chip group attached to the expanded tape in a face-down state on the second adhesive tape;
The light emitting element chip group obtained in the transfer step is face-up on a solid plate formed by adhering a polyimide film with an adhesive layer on a substrate harder than the second adhesive tape or the expanded tape. Affixing step, and then peeling off the second adhesive tape and batch transferring,
A bump forming step of forming a stud bump on the pad of the light emitting element chip;
The first adhesive tape is bonded to the light emitting element chip group obtained in the bump forming step from the stud bump side, and the light emitting element chip group is transferred to the first adhesive tape. , peeled polyimide film from the rigid substrate of the solid plate, and a placement step of arranging a face-down state the light-emitting element chip group the stud bumps are formed on the first adhesive tape,
Method for producing a surface-mount-type light-emitting device characterized by flip-chip mounting arranged on a substrate by taking the light-emitting element chips arranged in a face-down state on the first adhesive tape.

  According to the present invention, it is possible to realize a manufacturing method that enables flip chip mounting with a short assembly time while maintaining high luminance characteristics with a readily available light emitting element.

  The method for manufacturing a surface-mounted light-emitting device according to the present invention includes a wafer receiving process in which a light-emitting device chip group that has been diced on an expanded tape is attached face-up, and stud bumps are formed on the pads of the light-emitting device chips A bump forming step and an arrangement step of arranging the light emitting element chip group on which the stud bump is formed on the first adhesive tape in a face-down state, and arranged on the adhesive tape in a face-down state. The light emitting element chip is picked up and placed on a substrate for flip chip mounting. Also, a transfer step of rearranging the diced light emitting element chips attached to the expanded tape in a face-down state on the second adhesive tape, and the light emitting element chips obtained in the transfer step A fixing step of sticking in a face-up state to a solid plate harder than the second adhesive tape or the expanding tape, and the bump forming step was provided after the fixing step. Further, in the arranging step, the first adhesive tape is bonded to the light emitting element chip group obtained in the bump forming step from the stud bump side, and the light emitting element chip group is transferred to the first adhesive tape. ing.

FIG. 1 is a diagram for explaining a process of a method for manufacturing a flip chip mounting type surface mount light emitting device according to the present invention, and FIG. 2 is a process chart of a method for manufacturing a flip chip mounting type surface mount light emitting device according to the present invention.
In FIG. 1, (a) is a diagram showing the form of the LED chip received in the wafer receiving process. Like FIG. 6 (a), the LED chip 12 is face-up with the dicing chip on the expanded tape 16. In this state, that is, the chip pad 14 is affixed to the opposite surface of the expanded tape 16.
That is, the manufacturing method of the flip chip mounting type surface mounting type light emitting device according to the present invention is based on the premise that the bump is not formed at the wafer stage, but the wafer is diced before the bump formation and the light emitting device chip is made into small pieces. It is.
LED chips that are light emitting elements are generally supplied in such a form, and special specification wafers such as bump-formed wafers are not available unless there are special conditions. Therefore, the flip chip mounting type surface mounting type light emitting device manufacturing method according to the present invention can be applied to a so-called small quantity multi-product production product.

FIG. 1B shows the diced light emitting element chip 12 group attached to the expanded tape 16 in a face-down state on the second adhesive tape 17, that is, the chip pad 14 is placed on the surface of the expanded tape 16. FIG. 1A shows a transfer process for rearrangement after the adhesive strength of the expanded tape 16 has been weakened by, for example, irradiating the expanded tape 16 with ultraviolet light or applying heat. By sticking the second adhesive tape 17 to the pad side of the LED chip group in the state where it is in a state and peeling off the expanded tape 16, the LED chip group can be transferred to the second adhesive tape 17 at once.
As a result of this transfer process, the LED chip group that has been aligned in the face-up state is rearranged on the second adhesive tape 17 in a face-down state. The second adhesive tape 17 functions as a temporary fixing sheet.

FIG. 1C shows a fixing process in which the group of light emitting element chips 12 obtained in the transfer process is attached to a solid plate 21 that is harder than the second adhesive tape 17 or the expanded tape 16 in a face-up state. In the figure, for example, after the adhesive force is weakened by irradiating the second adhesive tape 17 with ultraviolet rays or applying heat, the rigid plate 21 is pressed against the back surface of the light emitting element chip 12 group, and the load After fixing the light emitting element chip 12 group to the hard solid plate 21, the second adhesive tape 17 is peeled off, whereby the LED chip group is collectively transferred to the hard solid plate 21. The light emitting element chips 12 are aligned on a hard plate 21 in a face-up state. Specifically, an adhesive sheet 22 that is cured by heat and load is attached to the back surface of the light emitting element chip 12 group, and a rigid solid plate 21 is applied and cured for 20 minutes to strengthen the fixing force.
The fixed plate 21 is configured such that the polyimide film 20 is bonded to the substrate 18, which is harder than the second adhesive tape 17 and the expanded tape 16, with an adhesive layer 23.

FIG. 1D is a view showing a bump forming process for forming stud bumps 24 on the pads of the light emitting element chip 12 group obtained in the fixing process, and the bump forming process is provided after the fixing process. .
In FIG. 3D, the light emitting element chip 12 group is fixed face-up on a rigid solid plate 21, so that stud bumps can be formed. In the bump forming step, the wire material bumps 24 are formed on the pads of the chip in such a manner that the wires are crushed by an apparatus similar to a wire bonder. Therefore, the material of the stud bump is almost always gold.
Here, it is necessary to pay attention to the fact that in the state where the chip is attached to the expanded tape, the expanded tape is too soft, so that it is impossible to form the stud bump. What is necessary is just to determine the hardness, material, etc. of the fixed plate 21 according to the characteristic which a stud bump forming machine requires.

FIGS. 1E and 1F are views for explaining an arrangement process of arranging the light emitting element chip 12 group on which the stud bump 24 is formed on the first adhesive tape 26 in a face-down state.
In the arrangement step, the first adhesive tape 26 is bonded from the stud bump side to the light emitting element chip 12 group obtained in the bump forming step. Then, when the first adhesive tape 26 is peeled off, the curing condition of the adhesive layer 23 is such that the light emitting element chip 12 group and the polyimide tape 23 are peeled off from the rigid substrate 18 and remain on the first adhesive tape 26 side as shown in the figure. The solidification conditions such as the above are set, and the light emitting element chip 12 group is transferred to the first adhesive tape 26. Such conditions can be set by selecting the material for the adhesive layer 23, selecting ultraviolet irradiation, and applying heat.
Next, if the polyimide tape 20, the adhesive layer 23, and the adhesive sheet 22 are removed from the first adhesive tape 26 and the group of light emitting element chips 12 aligned thereon, the first adhesive tape shown in FIG. Thus, a group of light emitting element chips 12 with stud bumps aligned on the face 26 in a face-down state is obtained.

In the manufacturing method of the present invention, the light emitting element chip 12 is picked up from the state shown in FIG. 1 (f) and placed on the collective substrate of the substrate 82 shown in FIG. 5, for example, printed with gold-tin solder. Flip chip mounting is performed by a reflow process.
When mounting, usually, a group of chips arranged face-up on the tape is picked up by a flip chip bonder, and the orientation is changed and placed on the substrate in a face-down state. However, the flip chip bonder takes time because it is necessary to change the direction of the chip, that is, the so-called tact time is long. Since the total tact time becomes larger as the number of chips integrated on the wafer increases, it becomes a big problem for an element having a relatively small number of chips such as a light emitting diode, that is, a large number of chips per wafer. It was.

However, in the manufacturing method of the present invention, as shown in FIG. 1 (f), since the chips are aligned in a face-down state, the chips can be placed on the substrate with a device that picks up the chips and places them at a desired position. . Since such an apparatus does not require changing the direction of the chip, the tact time can be reduced to a fraction of that of the flip chip bonder. For example, in the case of a general flip chip bonder, the tact time is about 3 seconds per chip, but when the die bonder is used without scrubbing, it can be set to about 0.3 seconds per chip.
Furthermore, in the manufacturing method of the present invention, since solder is used to connect the chip and the substrate, a self-alignment effect due to the tension of the solder can be expected. Therefore, the positional accuracy when the chip is placed can be lowered, and the apparatus can be further increased in speed or cost.

FIG. 2 is a diagram in which the steps described in FIG. 1 are arranged. Each step in the method for manufacturing a surface-mounted light emitting device of the present invention is configured in the following order.
Reference numeral 1 denotes a wafer receiving process, in which chips diced on the expanded tape 16 are received in a face-up state.
The next step 2 is a transfer step, in which the diced light emitting element chips 12 are collectively transferred so as to be arranged face down on the second adhesive tape 17 that functions as a temporary fixing sheet.

Reference numeral 3 denotes a fixing process, in which the light emitting element chip 12 group obtained in the transfer process is collectively transferred again to the solid plate 21 that is harder than the second adhesive tape 17 or the expanded tape 16 and aligned in a face-up state. Thus, stud bumps can be formed.
4 is a bump forming process, in which stud bumps are formed on chips arranged in a face-up state on a rigid substrate.

Reference numeral 5 denotes an arrangement step, in which the light emitting element chips 12 are collectively transferred again onto the first adhesive tape 26 and aligned in a face-down state.
Reference numeral 6 denotes a flip chip mounting process, which is a high-speed machine that simply picks up and places the light emitting element chips 12 aligned in a face-down state, and places them on a collective substrate on which solder is printed. Implement.

As described above, the method for manufacturing a surface-mounted light-emitting element of the present invention is a mounting method in which batch transfer is performed, bumping is performed, and batch transfer is performed using a heat-resistant temporary fixing sheet.
A conventional method for manufacturing a surface-mounted light emitting device of a flip chip mounting type has a problem of long assembling time. However, the present invention does not break the alignment state of the light emitting device chips 12 group and is mounted on a high speed machine. As a result, the assembly time has been greatly reduced.

FIG. 3 is a view for explaining the solid plate 21 which is harder than the second adhesive tape or the expanded tape.
FIG. 3 (a) is a reprint of FIG. 1 (c), and FIGS. 3 (b) and 3 (c) are diagrams illustrating the fixed plate 21 in FIG. 3 (a).
As shown in FIG. 3 (b), the fixed plate 21 is composed of a substrate 18 that is stiffer than the second adhesive tape 17 and the expanded tape 16, and a polyimide film 23 having an adhesive layer 23 on the lower surface. ), The rigid substrate 18 and the polyimide film 23 are bonded together by an adhesive layer 23.
In the formation, the setting of the hardness capable of forming the stud bump by setting the curing cure time to 20 minutes and the adhesive strength capable of peeling the rigid substrate 18 and the polyimide film 23 as described in FIG. Became possible.

As described above, according to the present invention, it is possible to realize a manufacturing method that enables flip chip mounting with a short assembly time while maintaining high luminance characteristics with a light-emitting element that is generally easily available. .
For example, it is possible to shorten the assembly time by using a wafer on which bumps have been formed. However, considering that the procurement restrictions are large and the realization is not easy, the effect of the present invention is considered to be great.
In addition, since the method for manufacturing a surface-mounted light emitting device according to the present invention is intended for a light emitting device having a generally available form, it can be applied to a product of so-called low-volume, multi-product production.
Furthermore, the manufacturing method according to the present invention is naturally effective for flip chip mounting of chips other than light emitting elements.

It is a figure explaining the process of the manufacturing method of the surface mount type light emitting element by this invention. It is process drawing of the manufacturing method of the surface mount type light emitting element by this invention. It is a figure explaining the solid board harder than a 2nd adhesive tape or an expanded tape. It is sectional drawing of a wire bonding mounting type surface mount type LED. It is sectional drawing of a flip chip mounting type surface mount type LED. It is the figure which showed the conventional process in the case of carrying out flip chip connection of the gold bump goods by the reflow method.

Explanation of symbols

16 Expanded tape 12 Light emitting device chip
14 Pad
24 Stud Bump 26 First Adhesive Tape 98 Surface Mount Light Emitting Element 17 Second Adhesive Tape 21 Solid Plate 18 Substrate Harder than Second Adhesive Tape or Expanded Tape
20 Polyimide film

Claims (1)

In the method for manufacturing the surface-mounted light emitting device,
A wafer receiving process in which a dicing light-emitting element chip group is attached to the expanded tape in a face-up state;
A transfer step of rearranging the diced light emitting element chips attached to the expanded tape in a face-down state on the second adhesive tape;
The light emitting element chip group obtained in the transfer step is face-up on a solid plate formed by adhering a polyimide film with an adhesive layer on a substrate harder than the second adhesive tape or the expanded tape. Affixing step, and then peeling off the second adhesive tape and batch transferring,
A bump forming step of forming a stud bump on the pad of the light emitting element chip;
The first adhesive tape is bonded to the light emitting element chip group obtained in the bump forming step from the stud bump side, and the light emitting element chip group is transferred to the first adhesive tape. , peeled polyimide film from the rigid substrate of the solid plate, and a placement step of arranging a face-down state the light-emitting element chip group the stud bumps are formed on the first adhesive tape,
Method for producing a surface-mount-type light-emitting device characterized by flip-chip mounting arranged on a substrate by taking the light-emitting element chips arranged in a face-down state on the first adhesive tape.

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