JP2008147510A - Flip-chip mounting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flip-chip mounting method for eliminating voids generated in a heat bonding process by overheating a semiconductor device for which bonding is completed altogether again. <P>SOLUTION: In the flip-chip mounting method, a semiconductor chip 10 and a wiring circuit board 1 are bonded by heating and press-fixing the bump 12 of the semiconductor chip 10 and metal plating 3 which is the electrode of the wiring circuit board 1 and they are sealed by resin compositions 6, 6A and 6B for a sealing filler interposed between them. Then, by heating at least a part of the semiconductor chip 10 and the wiring circuit board 1 to such a temperature that the resin compositions 6, 6A and 6B for the sealing filler, the voids inside the resin compositions 6, 6A and 6B for the sealing filler are eliminated. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a flip-chip mounting method for a semiconductor element in which a semiconductor element is mounted on a printed circuit board in a face-down manner.

  As electronic devices become smaller, lighter, and thinner, semiconductor devices and printed circuit boards are required to be smaller, lighter, and thinner. Generally, a semiconductor element is mounted on a printed circuit board. As a method of mounting a semiconductor element on a printed circuit board, a flip chip mounting method is used in which bumps of the semiconductor element and electrodes of the printed circuit board are joined and connected using solder or a eutectic metal. Further, in order to reduce the size, weight, and thickness of the printed circuit board, the printed circuit board material has shifted from a rigid material such as glass epoxy to a flexible material such as polyimide film.

  In the flip chip mounting method, there is a problem in connection reliability against thermal shock due to the difference in coefficient of linear expansion between the semiconductor element and the printed circuit board. To improve this, a sealing filler is used between the semiconductor element and the printed circuit board. It is common. With this sealing filler, stress generated at the joint is relaxed and connection reliability is improved.

  A conventional method of forming a sealing filler at the time of flip-chip mounting is to join a semiconductor element and a printed circuit board at a high temperature, and then inject and fill a gap with a low-viscosity thermosetting liquid resin composition by capillary action. However, a method of thermosetting has been used. However, this method has a problem that if the wiring gap or the gap between the semiconductor element and the wiring board is further narrowed (fine pitch), the working efficiency is lowered and filling becomes difficult.

  Therefore, a thermosetting liquid resin composition is previously applied or pasted to a predetermined position of a semiconductor element or a printed circuit board immediately before bonding, and then the electrode of the semiconductor element and the electrode of the printed circuit board are thermocompression bonded. Thus, a method for sealing and filling the gap has been studied.

  The sealing filler suitably used in this method can maintain an appropriate thickness during application and pasting, and can fill the gap between the semiconductor element and the printed circuit board without gaps with an appropriate flowability when heated and bonded.・ No decomposition or foaming due to heating at the time of joining, solidification at an appropriate temperature and speed, high electrical insulation when solidified, no corrosive factor to the electrodes on the wiring circuit board, wiring circuit board In order to relieve stress between peripheral members such as semiconductor elements and solder resists, a low elastic modulus is required.

  As such a sealing filler, an epoxy resin-based thermosetting resin is suitably used, and attempts have been made to lower the elastic modulus (Patent Document 1). Attempts have also been made to use thermosetting resin films (Patent Document 2).

  As described above, in the flip chip mounting method in which the sealing filler is disposed in advance, a void generated when the semiconductor element and the printed circuit board are bonded by heat bonding or ultrasonic bonding has been a problem. It has been found that voids adversely affect the reliability of semiconductor devices such as connection reliability and insulation reliability. In order to suppress this, there has been proposed a flip chip mounting method that suppresses voids by cooling a semiconductor device containing a resin during heat bonding and releasing the pressure (Patent Document 3). There has also been proposed a method in which the curing is almost completely completed and the pressure is released after the resin is solidified (Patent Documents 4 and 5).

JP 2004-10810 A JP 2005-112916 A Japanese Patent No. 3646056 JP-A-11-282547 JP 2005-48054 A

  In the flip chip mounting method in which the sealing filler is arranged in advance, the voids generated in the sealing filler are often caused by bubbles contained in moisture or resin, or bubbles entrained during bonding. It has been said. However, according to the inventor's investigation, these bubbles can be almost eliminated by the flow of the filler at the time of joining. Many of the voids that cannot be eliminated are sealed and filled when the bump and the wiring are joined by heating and pressurizing. It was found that this occurs when the pressure is released while the material is in a liquid state.

  According to the inventor's investigation, it has been found that the generated void can be suppressed by releasing the pressure at the time of joining in a state where the sealing filler is solidified. That is, in the above-mentioned Patent Documents 3, 4 and 5, the process is performed without knowing the cause of the void generation. In the methods described in Patent Documents 3, 4 and 5, although voids can be suppressed, temperature control at the time of joining requires a lot of time, and there is a problem that productivity is lowered.

  In order to improve the manufacturing efficiency of a semiconductor device in flip-chip mounting, the present invention is directed to a semiconductor device that eliminates voids generated in a heat bonding process by reheating and heating the semiconductor devices that have been bonded together. An object of the present invention is to provide a flip chip mounting method as a manufacturing method.

  That is, in the flip chip mounting method according to the present invention, the gap between the semiconductor chip and the printed circuit board is sealed with the sealing filler resin composition, and then the sealing filler resin composition is melted. By heating at least a part of the semiconductor chip and the printed circuit board, voids in the resin composition for sealing filler are eliminated.

  Further, in the flip chip mounting method according to the present invention, the resin composition for sealing filler is interposed on at least one facing surface of the semiconductor chip and the printed circuit board, and the bump of the semiconductor chip and the wiring Sealing the gap between the semiconductor chip and the wired circuit board with the resin composition for sealing filler by bonding the electrodes of the circuit board by thermocompression bonding to the semiconductor chip and the wired circuit board. Features.

  Further, in the flip chip mounting method according to the present invention, a resin composition for a sealing filler is applied or pasted on a semiconductor wafer, the semiconductor wafer is diced to produce a semiconductor chip, and the sealing filler The semiconductor chip on the surface to which the resin composition for application or application is applied is laminated so as to face the wiring circuit board, and the bumps of the semiconductor chip and the electrodes of the wiring circuit board are heat-pressed to bond the semiconductor chip and the semiconductor chip. Bonding the printed circuit board, sealing the gap between the semiconductor chip and the printed circuit board with the resin composition for sealing filler, and then to a temperature at which the resin composition for sealing filler can be melted By heating at least a part of the semiconductor chip and the printed circuit board, voids in the resin composition for sealing filler are eliminated.

  In the flip chip mounting method according to the present invention, the temperature for heating at least a part of the semiconductor chip and the printed circuit board is 100 ° C. to 350 ° C.

  In the flip chip mounting method according to the present invention, the time for heating at least a part of the semiconductor chip and the printed circuit board is 2 minutes to 360 minutes.

  In the flip chip mounting method according to the present invention, the printed circuit board is a flexible printed board.

  In the flip chip mounting method according to the present invention, the sealing filler resin composition contains a thermoplastic resin.

  The flip chip mounting method according to the present invention is characterized in that the thermoplastic resin is a polyolefin-based thermoplastic resin.

  According to the present invention, voids in the resin composition for sealing filler are eliminated by heating at least a part of the semiconductor chip and the printed circuit board to a temperature at which the resin composition for sealing filler can be melted. Therefore, the void can be eliminated in a short time, and the manufacturing efficiency of the voidless semiconductor device can be improved.

  Hereinafter, a flip chip mounting method according to the present invention will be described in detail with reference to the drawings in accordance with a preferred embodiment. Note that the present invention is not limited to the following embodiments.

[Embodiment 1]
1 to 7 are schematic cross-sectional views illustrating a process of a flip chip mounting method according to the first embodiment in which a semiconductor chip and a printed circuit board are bonded to each other with a resin composition for sealing filler interposed on the printed circuit board. It is. In addition, in each figure, the same code | symbol shows the same or equivalent part.

  As shown in FIG. 1, a copper wiring 2 is formed on a top surface of a film-like base material 1 as a wiring circuit board, excluding a portion where a semiconductor chip is mounted, and a predetermined portion on the copper wiring 2. Is provided with a metal plating 3 such as tin or gold. The printed circuit board is not limited to the film-like substrate 1, and various circuit boards can be used. Further, as the metal plating 3, tin or gold plating can be suitably used, but plating of other metals may be used and can be used in the same manner. Further, a solder resist 4 that is a heat-resistant coating material is formed on the copper wiring 2 as a protective film such as a pattern other than the joint portion.

  Dispensing is mentioned as a general dripping and application method, and application is possible by heating the resin composition for sealing filler before application to the melting temperature to make it liquid. As heating temperature, 140 to 250 degreeC is preferable and 160 to 220 degreeC is more preferable.

  For example, as shown in FIG. 2, a liquid resin composition 6 for sealing filler is dropped by a dispenser nozzle 100 so as to cover the mounting position 5 where the semiconductor chip of the film-like substrate 1 is mounted. The resin composition 6 for sealing filler can be dripped with a desired thickness and shape according to the distance between the semiconductor chip and the film-like substrate 1, the size of the semiconductor chip, and the like.

  Alternatively, as shown in FIGS. 3 and 4, the sealing filler resin composition 6 </ b> A is mounted in a predetermined manner by sticking a sheet-like sealing filler resin composition 6 </ b> A and temporarily pressing the roller 200 with the resin composition 6 </ b> A. It can be placed at position 5. Here, in order to improve the sticking property of the sealing filler resin composition 6A, moderate heat may be applied at the time of provisional pressure bonding. Furthermore, as shown in FIG. 5, it is also possible to arrange | position the pellet-shaped resin composition 6B for sealing fillers in the mounting position 5 in which the semiconductor chip of the film-form base material 1 is mounted, for example. The liquid sealing filler resin composition 6 shown in FIG. 2 and the pellet-shaped sealing filler resin composition 6B shown in FIG. 5 are pressed by a pressing member (not shown) as needed. The step of flattening may be included as shown in FIG. In addition, the method and conditions, such as application | coating of a resin composition for sealing fillers, dripping, and affixing, are not specifically limited, A various method is employable. Further, the thickness of the resin composition 6, 6A, 6B for sealing filler interposed between the film-like substrate 1 and the semiconductor chip 10 generally depends on the height of the wiring, etc., but is about 50. ~ 150 μm.

  As shown in FIG. 6, the semiconductor chip 10 has bumps 12 formed on its lower surface via metal posts 11. The lower surface of the semiconductor chip 10 on which the bumps 12 are formed is opposed to the upper surface of the film-like substrate 1 on which the resin composition 6, 6 </ b> A, 6 </ b> B for sealing filler is disposed and the metal plating 3 is formed. The semiconductor chip 10 and the film-like substrate 1 are pressed by the pressing device 15 while being heated at a temperature. At this time, an ultrasonic wave or the like may be applied for bonding, and a uniform layer of the resin composition for sealing filler 6, 6A, 6B is formed by such ultrasonic bonding, and variation in mounting state is suppressed. be able to.

  As described above, as shown in FIG. 7, the bump 12 of the semiconductor chip 10 and the metal plating 3 of the film-like substrate 1 are bonded, and the vicinity of the bonding portion between the bump 12 and the metal plating 3 is sealed. The flip chip mounting product 20 filled and sealed with the resin composition for filler 6, 6A, 6B can be manufactured.

  Subsequently, the sealing filler is heated by heating at least a part of the semiconductor chip and the printed circuit board to a temperature at which the resin composition for sealing filler 6, 6A, 6B can be melted (hereinafter referred to as a heating step). A step of eliminating voids in the resin composition for use.

  In the flip chip mounting method in which the sealing filler resin composition is preliminarily disposed, the pressure applied during the heat bonding is released in a state where the sealing filler resin composition is melted, so that the semiconductor element and the wiring A void caused by springback occurs between the substrates. The generated void is not caused by air or the like entering from the outside, but is a vacuum void generated from the inside.

  The present invention eliminates voids generated in the heat bonding step by collectively reheating at least part of the semiconductor devices (semiconductor chip and wiring circuit board) that have been bonded together. That is, after bonding the semiconductor chip and the printed circuit board, by providing a step of heating the whole or a part of the printed circuit board on which the semiconductor chip is mounted, by melting the sealing filler resin composition in the semiconductor device, It becomes possible to eliminate voids.

  Heating in the heating step in the present invention is performed at a temperature in the range of 100 ° C to 350 ° C. Furthermore, the heating temperature is preferably 120 ° C to 300 ° C, more preferably 150 ° C to 250 ° C, and particularly preferably 180 ° C to 220 ° C. When the heating temperature is less than 100 ° C., void disappearance is not sufficient, and when it exceeds 350 ° C., the resin composition for sealing filler may flow out, which is not preferable.

  Moreover, although the heating time in a heating process is based also on melting | fusing point of resin used for the resin composition for sealing fillers, 2 minutes-360 minutes are preferable, 5 minutes-120 minutes are more preferable, 10 minutes-60 minutes are Particularly preferred. If the heating time is less than 2 minutes, voids are not sufficiently lost, and voids can be eliminated without exceeding 360 minutes. Therefore, in order to shorten the mounting time, it is preferable that the voids be within 360 minutes.

  By the heating process as described above, it is possible to remove voids that adversely affect the reliability of the semiconductor device, such as bonding reliability and insulation reliability. Therefore, a highly reliable semiconductor device can be manufactured.

  The resin composition for sealing filler used in the present invention preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyolefin, polyvinylidene fluoride, polyester, polyacrylonitrile, polystyrene, polyamide, polyimide, polyphenylene, and the like. Any resin can be used as long as it melts at a temperature lower than the heat resistance temperature of the semiconductor device. Absent. These thermoplastic resins can be used individually by 1 type or in combination of 2 or more types according to use conditions, for example, use temperature. Since the thermoplastic resin is excellent in stability, there is no limitation on the standing time until the heat bonding after the sealing filler resin composition is applied, dropped, and pasted to the printed circuit board or the semiconductor chip in advance.

  Moreover, in order to further improve characteristics, such as heat-resistant stability, the sealing filler resin composition used for this invention can be mix | blended with various additives. Examples of such additives include antifoaming agents, silane coupling agents, inorganic or organic fillers, and pigments.

  Generally, in the case of AC insulation, the electrical insulation has a correlation with the dielectric constant of the resin, and it is preferable to use a resin having a low polarity for the resin composition for sealing filler. In addition, the electrode corrosion of the printed circuit board in the continuous voltage application test under high temperature and high humidity has a correlation with the water absorption and isohumidity of the resin composition for the sealing filler, and therefore has a low affinity for moisture. It is preferable to use a resin having a small number of groups.

[Embodiment 2]
8 to 12 are schematic cross-sectional views for explaining a process of the flip chip mounting method according to the second embodiment in which the resin composition for the sealing filler is arranged on the semiconductor chip and the semiconductor chip and the printed circuit board are bonded together. .

  In the first embodiment, the case where the resin composition for the sealing filler is disposed on the wiring circuit board and the semiconductor chip and the wiring circuit board are joined is described. In the second embodiment, the semiconductor before dicing is performed. The case where the resin composition for sealing fillers is arrange | positioned to a wafer, for example, a silicon wafer is demonstrated.

  First, as shown in FIG. 8, a sheet-like resin composition 6C for sealing filler is affixed on the silicon wafer 50 using, for example, a laminator (not shown). Further, when the liquid sealing filler resin composition 6D is applied onto the silicon wafer 50, as shown in FIG. 9, the liquid sealing is applied from the spin coat nozzle 300 onto the rotating silicon wafer 50. By dropping the resin composition for filler 6D, a uniform film-like resin composition for sealing filler 6D can be applied.

  Next, as shown in FIG. 10, the silicon wafer 50 is cut into a large number of semiconductor chips 10 by dicing, and as shown in FIG. 11, the resin compositions 6C and 6D for sealing filler are applied to each semiconductor chip 10 or It will be in the pasted state. In FIG. 11, illustration of the metal posts 11 and the bumps 12 provided on the semiconductor chip 10 is omitted.

  Next, as shown in FIG. 12, the lower surface of the semiconductor chip 10 on which the bumps 12 are formed and the sealing filler resin compositions 6C and 6D are applied or pasted is formed on the film-like substrate on which the metal plating 3 is formed. The semiconductor chip 10 and the film-like substrate 1 are pressed by the pressing device 15 while facing the upper surface of the material 1 and heating at a predetermined temperature. At this time, it is the same as in Embodiment 1 that ultrasonic waves may be applied for bonding.

  As described above, the bump 12 of the semiconductor chip 10 and the metal plating 3 of the film-like substrate 1 are bonded, and the vicinity of the bonding portion between the bump 12 and the metal plating 3 is sealed with a resin composition 6C for sealing filler. The flip chip mounting product 30 filled and sealed with 6D can be manufactured.

  Subsequently, the sealing filler resin compositions 6C and 6D are heated by heating at least a part of the semiconductor chip and the printed circuit board to a temperature at which the sealing filler resin compositions 6C and 6D can be melted. A step of eliminating voids is performed. Since the heating step can be performed under the same conditions as in the first embodiment, such as the heating temperature and the heating time, description thereof is omitted. Moreover, since the same material as Embodiment 1 can be used also about the resin composition for sealing fillers and another additive, description is abbreviate | omitted.

  In Embodiment 2, since the sealing filler resin composition is applied or pasted to the semiconductor wafer in advance, the sealing filler resin composition can be collectively disposed on the semiconductor wafer, so that the mounting operation is performed. Can be done efficiently.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the examples.

(Mounting specimen preparation method)
Apply a sealing filler resin composition to a flexible substrate for testing JKIT COF TEG 30-A (manufactured by Hitachi ULSI Systems Co., Ltd., solder resist: manufactured by Hitachi Chemical Co., Ltd., product name: SN-9000 coated product), or A special TEG chip, JTEG Phase630, was bonded by thermo-compression using a thermal ultrasonic combined flip chip bonder for 1.5 seconds under the conditions of a head temperature of 200 ° C., a stage temperature of 80 ° C., and a pressure of 180 N / chip. In addition, the resin composition for sealing fillers to be described later was used as the resin composition for sealing fillers (hereinafter referred to as compositions A to D). Thereafter, ultrasonic bonding was performed with an amplitude of 3 μm for 0.5 seconds to prepare a sample (test piece) of the mounted test semiconductor device.

Subsequently, the prepared sample was heat-treated on a hot plate under the following conditions a to d.
Condition a: 200 ° C., 30 minutes Condition b: 175 ° C., 60 minutes Condition c: 250 ° C., 20 minutes Condition d: No heat treatment

Composition A
As the sealing filler resin composition, a polypropylene-terpene resin-based thermoplastic resin composition (manufactured by Hitachi Chemical Polymer Co., Ltd., trade name: Hibon YH171-7P) was used to prepare the test piece for evaluation.

Composition B
The test piece for evaluation was prepared using a polyamide-based thermoplastic resin composition (manufactured by Hitachi Chemical Co., Ltd., trade name: Hibon XH055-6) as the resin composition for sealing filler.

Composition C
As the sealing filler resin composition, a styrene-butadiene rubber thermoplastic resin composition (manufactured by Hitachi Chemical Polymer Co., Ltd., trade name: Hibon 9610) was used to prepare the test piece for evaluation.

Composition D
The test piece for evaluation was prepared using an epoxy thermosetting resin composition sealing filler (trade name: RC281C, manufactured by Hitachi Chemical Co., Ltd.) as the sealing filler resin composition.

(Evaluation of void disappearance)
For evaluation of void disappearance, each sample was observed from the back surface using a microscope with a magnification of 100 times, and the occurrence of voids was evaluated twice. The observation results of voids are shown in Table 1. In Table 1, those in which voids of 3 μm or more were observed were evaluated as “×”, and those in which voids of 3 μm or more were not observed were evaluated as “◯”.

  As is clear from Table 1, in Experimental Examples 1 to 3, the voids disappeared in the sealing filler resin composition using the thermoplastic resin composition by heat treatment at 200 ° C. for 30 minutes. On the other hand, in Experimental Example 4, in the sealing filler resin composition using the epoxy thermosetting resin composition, voids did not disappear by heat treatment at 200 ° C. for 30 minutes.

  As described above, the flip chip mounting method according to the present invention heats at least a part of the semiconductor chip and the printed circuit board to a temperature at which the resin composition for the sealing filler can be melted. Since voids in the composition are eliminated, the manufacturing efficiency of the voidless semiconductor device can be improved. Further, it is suitable for manufacturing a semiconductor device with high reliability such as bonding reliability and insulation reliability.

In Embodiment 1, it is a schematic sectional drawing of the wiring circuit board explaining the process of the flip-chip mounting method which apply | coats the resin composition for sealing fillers. It is a schematic sectional drawing which shows the state which dripped the liquid resin composition for sealing fillers to the printed circuit board of FIG. It is a schematic sectional drawing which shows the state which affixed the sheet-like resin composition for sealing fillers on the printed circuit board of FIG. It is a schematic sectional drawing which shows the state which pressure-bonded the resin composition for sealing fillers to the printed circuit board of FIG. It is a schematic sectional drawing which shows the state which has arrange | positioned the pellet-form resin composition for sealing fillers to the printed circuit board of FIG. It is a schematic sectional drawing which shows the state which heat-presses a semiconductor chip and a wiring circuit board by interposing the resin composition for sealing fillers in between. It is a schematic sectional drawing which shows the flip chip mounting goods which sealed the semiconductor chip and the wiring circuit board with the resin composition for sealing fillers. In Embodiment 2, it is a schematic perspective view which shows the state which affixes the sheet-like resin composition for sealing fillers on a silicon wafer. It is a schematic perspective view which shows the state which spin-coats the resin composition for liquid sealing fillers on a silicon wafer. It is a schematic perspective view which shows the state which dices the silicon wafer to which the resin composition for sealing fillers was affixed or apply | coated. It is a schematic perspective view which shows a semiconductor chip. It is a schematic sectional drawing which shows the flip chip mounting goods which sealed the semiconductor chip and the wiring circuit board with the resin composition for sealing fillers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film-like base material 2 Copper wiring 3 Metal plating 4 Solder resist 5 Semiconductor chip mounting position 6, 6A-6D Resin composition for sealing filler 10 Semiconductor chip 11 Metal post 12 Bump 15 Press device 20, 30 Flip chip mounting Product 50 Silicon wafer 100 Dispenser nozzle 200 Roller 300 Spin coat nozzle 300

Claims (8)

  The gap between the semiconductor chip and the printed circuit board is sealed with a resin composition for sealing filler, and then at least one of the semiconductor chip and the printed circuit board at a temperature at which the resin composition for sealing filler can be melted. The void in the resin composition for sealing fillers is eliminated by heating a part, The flip chip mounting method characterized by the above-mentioned.   The resin composition for sealing filler is interposed between at least one opposing surface of the semiconductor chip and the printed circuit board, and the semiconductor chip and the bump of the semiconductor chip and the electrode of the wired circuit board are thermocompression bonded. 2. The flip chip mounting method according to claim 1, wherein the gap between the semiconductor chip and the wired circuit board is sealed with the resin composition for sealing filler by bonding the wired circuit board.   A semiconductor composition for sealing filler is applied or pasted on a semiconductor wafer, a semiconductor chip is manufactured by dicing the semiconductor wafer, and the surface of the surface on which the resin composition for sealing filler is coated or pasted A semiconductor chip is stacked opposite to a wiring circuit board, and bumps of the semiconductor chip and electrodes of the wiring circuit board are thermocompression bonded to bond the semiconductor chip and the wiring circuit board, and the semiconductor chip and the wiring circuit The gap between the substrates is sealed with the resin composition for sealing filler, and then at least a part of the semiconductor chip and the printed circuit board is heated to a temperature at which the resin composition for sealing filler can be melted. By this, the void in the said resin composition for sealing fillers is lose | disappeared, The flip-chip mounting method characterized by the above-mentioned.   4. The flip-chip mounting according to claim 1, wherein a temperature for heating at least a part of the semiconductor chip and the printed circuit board is 100 ° C. to 350 ° C. 5. Method.   The flip chip mounting according to any one of claims 1 to 4, wherein a time for heating at least a part of the semiconductor chip and the printed circuit board is 2 minutes to 360 minutes. Method.   The flip-chip mounting method according to claim 1, wherein the printed circuit board is a flexible printed circuit board.   The flip-chip mounting method according to claim 1, wherein the sealing filler resin composition includes a thermoplastic resin.   The flip-chip mounting method according to claim 7, wherein the thermoplastic resin is a polyolefin-based thermoplastic resin.

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