JP6530234B2 - Electronic component mounting apparatus and electronic component mounting method - Google Patents

Description

  The present invention relates to an electronic component mounting apparatus and a method of mounting an electronic component.

  The semiconductor device includes a wiring board and a semiconductor chip mounted on the wiring board. Conventionally, a semiconductor chip is mounted on a wiring substrate by flip chip mounting, for example. Bumps of solder, gold or the like are formed on the semiconductor chip. Solder bumps are formed on the connection pads of the wiring substrate. The semiconductor chip and the wiring substrate adsorbed to the head by vacuum suction are aligned with each other, and the semiconductor chip is mounted on the wiring substrate. Then, the solder on the wiring substrate is melted by collective reflow (mass reflow) or individual reflow (local reflow), and the semiconductor chip is mounted on the wiring substrate (for example, see Patent Documents 1 to 3).

JP 2003-31993 A JP, 2012-94725, A International Publication No. 2012/073282

  By the way, in the case of component mounting by collective reflow, connection failure may occur depending on the size of the semiconductor chip and the like. In the case of component mounting by individual reflow, the alignment accuracy affects the mounting accuracy, and there is a possibility that positional deviation may occur. These lead to a reduction in the reliability of the semiconductor device.

According to one aspect of the present invention, there is provided an electronic component mounting apparatus for mounting an electronic component on a wiring board, the apparatus including a heater, a stage for holding the wiring board, and a holding tool for holding the electronic component. And a control unit for controlling the heater and the head unit, and the control unit is configured to move the gas from the flow path of the holding tool. The connection terminals of the electronic component suctioned and held by suction are pressed against the solder bumps of the wiring substrate, the solder bumps are heated by the heater, and the holding of the electronic components is performed after the solder bumps are melted. By discharging a gas between the holding tool and the electronic component from the flow path, a vacuum region is generated between the lower surface central portion of the holding tool and the electronic component, and the electronic unit Switching to the non-contact holding which holds in a non-contact, while the non-contact holding said electronic component, and to so that is self-aligning the electronic component by the surface tension of the solder bumps melt.

  According to one aspect of the present invention, the decrease in reliability can be suppressed.

(A) is a top view of an electronic component mounting apparatus, (b) is a front view of an electronic component mounting apparatus. The schematic side view of a head part. The block diagram which shows the electric constitution of the electronic component mounting apparatus. Explanatory drawing of a semiconductor chip and a wiring board. Schematic explaining the alignment by a camera. Explanatory drawing which shows the process of component mounting. The schematic sectional drawing which shows the process of component mounting. The schematic sectional drawing which shows the process of component mounting. The schematic sectional drawing which shows the process of component mounting. The schematic sectional drawing which shows the process of component mounting. Explanatory drawing which shows the process of a comparative example. (A)-(d) is a schematic sectional drawing which shows a mass reflow process. (A), (b) is a schematic sectional drawing which shows a local reflow process.

Hereinafter, one embodiment will be described.
The attached drawings may show components in an enlarged manner for easy understanding. The dimensional proportions of the components may differ from the actual ones or from one in another drawing. In addition, in the cross-sectional view, hatching of some components may be omitted to facilitate understanding.

  As shown in FIG. 1A, the electronic component mounting apparatus 10 has a base 11 formed in a substantially rectangular parallelepiped shape. As shown in FIG. 1 (b), a plurality of legs 12 are attached to the lower surface of the base 11. An XY stage 13 is fixed to the upper surface of the base 11.

  The XY stage 13 has a table 13a and a drive mechanism 13b for moving the table 13a. The wiring substrate 60 is placed on the top surface of the table 13a. The table 13 a holds the wiring board 60. The table 13a has a heater function and heats the wiring substrate 60 placed on the upper surface.

  The drive mechanism 13 b moves the table 13 a in the X axis direction (vertical direction in FIG. 1A) and in the Y axis direction (horizontal direction in FIG. 1A). Further, the drive mechanism 13b moves (horizontally rotates) the table 13a in the θ axis direction. For example, the drive mechanism 13 b has a guide rail of each axis (X axis, Y axis, θ axis) and a motor. The motor is, for example, a servomotor or a stepping motor. The drive mechanism 13 b has a ball screw connected to a motor (output shaft) of the X axis and the Y axis. The table 13a moves along the X-axis direction and the Y-axis direction by the forward and reverse rotation of the ball screw. In addition, the table 13a rotates in the forward and reverse directions by the θ-axis motor.

  In addition, a gate-shaped frame 14 is installed on the upper surface of the base 11. A head portion 15 is attached to a side surface (a front surface in FIG. 1B) 14 a of the frame 14. The head unit 15 has a holding tool 29.

  Further, a chip table 16 and a chip transfer robot 17 are fixed to the upper surface of the base 11. In FIG. 1 (b), the chip transfer robot 17 is omitted. The semiconductor chip 50 is mounted on the top surface of the chip table 16. The semiconductor chip 50 is an example of an electronic component mounted on the wiring substrate 60. The chip transfer robot 17 transfers the chip on the chip table 16 to the head unit 15. Then, the electronic component mounting apparatus 10 holds the semiconductor chip 50 by the holding tool 29 and mounts the semiconductor chip 50 on the wiring substrate 60.

Here, the target electronic component (semiconductor chip) and the wiring board will be described.
FIG. 4 shows a semiconductor chip 50 and a part of a wiring board 60 on which the semiconductor chip 50 is mounted. The semiconductor chip 50 is an example of an electronic component mounted on the wiring substrate 60.

  The semiconductor chip 50 has a chip body 51 and a plurality of bumps 52 disposed on one surface (the lower surface in FIG. 4) of the chip body 51. The chip body 51 includes, for example, elements and wirings formed on a silicon substrate or a sapphire substrate. The surface on which these elements and wirings are formed is referred to as an element formation surface. The plurality of bumps 52 are formed on the element forming surface of the chip body 51.

  As the chip main body 51, for example, a logic chip such as a central processing unit (CPU) chip or a graphics processing unit (GPU) chip can be used. In addition, as the chip main body 51, for example, a memory chip such as a dynamic random access memory (DRAM) chip, a static random access memory (SRAM) chip, or a flash memory chip can be used.

  The shape of the bumps 52 is, for example, a column such as a cylinder. The material of the bumps 52 is, for example, a metal such as copper (Cu) or gold (Au). The bumps 52 may be solder bumps. As a material of the solder bumps, for example, an alloy of tin (Sn) and gold (Au), an alloy of Sn and copper (Cu), an alloy of Sn and silver (Ag), an alloy of Sn, Ag and Cu, etc. Can.

  The wiring substrate 60 has a substrate body 61. The substrate body 61 is, for example, a buildup substrate with a core including the core substrate 61a and the wiring layer 61b on the upper surface of the core substrate 61a. The core substrate 61a includes, for example, a substrate such as copper (Cu) or aluminum (Al), an insulating film formed on the surface of the substrate, a through electrode penetrating the substrate, and the like. An insulating substrate such as ceramic may be used as the substrate of the core substrate 61a, and in this case, the insulating film on the surface of the substrate may not be provided.

  The wiring layer 61 b has, for example, a multilayer structure in which insulating layers and wiring layers are alternately stacked, and the wiring layers are connected by vias formed in the insulating layers. For example, copper or a copper alloy can be used as the material of the wiring layer or the via. As a material of the insulating layer, for example, an insulating resin such as an epoxy resin or a polyimide resin, or a resin material in which a filler such as silica or alumina is mixed with the resin can be used.

  A wiring layer 62 and a solder resist layer 63 are formed on the upper surface of the substrate body 61. A wiring layer 64 and a solder resist layer 65 are formed on the lower surface of the substrate body 61. As a material of the wiring layers 62 and 64, copper (Cu) can be used, for example.

  It is sufficient that the substrate body 61 have a structure for electrically connecting the wiring layer 62 and the wiring layer 64 to each other. For this reason, a wiring layer may be formed inside the substrate main body 61, and the wiring layer may not be formed. Further, a coreless substrate or the like having no core substrate can be used as the substrate body 61.

  The solder resist layer 63 is provided to cover the upper surface of the substrate body 61. The solder resist layer 63 has an opening 63 a that exposes part of the wiring layer 62. As a material of the solder resist layer 63, for example, an insulating resin such as an epoxy resin or an acrylic resin can be used.

  A surface treatment layer 66 is formed on the surface of the wiring layer 62 exposed by the opening 63 a. The surface treatment layer 66 is exposed by the opening 63 a and functions as a pad for connecting an electronic component. When the surface treatment layer 66 is not formed, the wiring layer 62 exposed from the opening 63 a functions as the pad.

  The solder resist layer 65 is provided to cover the lower surface of the substrate body 61. The solder resist layer 65 has an opening 65 a that exposes part of the wiring layer 64. As a material of the solder resist layer 65, for example, an insulating resin such as an epoxy resin or an acrylic resin can be used.

  A surface treatment layer 67 is formed on the wiring layer 64 exposed by the opening 65 a. The surface treatment layer 67 functions as a pad for connecting the wiring substrate 60 to another substrate (for example, a mother board). When the surface treatment layer 67 is not formed, the wiring layer 64 exposed from the opening 65 a functions as the pad.

  The surface treatment layers 66 and 67 are films having conductivity, such as a metal layer and an OSP (Organic Solderability Preservative) film. As a metal layer, a gold (Au) layer, a nickel (Ni) layer / Au layer (a metal layer in which a Ni layer and an Au layer are laminated in this order on the wiring layer 62), a Ni layer / palladium (Pd) layer And an Au layer (a metal layer in which a Ni layer, a Pd layer, and an Au layer are stacked in this order on the wiring layer 62) and the like can be mentioned. As the Ni layer, the Au layer, and the Pd layer, for example, a metal layer (electroless plating metal layer) formed by electroless plating can be used. The Au layer is a metal layer made of Au or an Au alloy, the Ni layer is a metal layer made of Ni or a Ni alloy, and the Pd layer is a metal layer made of Pd or a Pd alloy. The OSP film is a film formed by performing an oxidation preventing process such as an OSP process on the wiring layers 62 and 64 exposed from the openings 63 a and 65 a.

  Solder bumps 68 are formed on the surface treatment layer 66. As a material of the solder bumps 68, for example, a lead such as an alloy of tin (Sn) and gold (Au), an alloy of Sn and copper (Cu), an alloy of Sn and silver (Ag), an alloy of Sn, Ag and Cu, etc. Material can be used. The solder bumps 68 are formed, for example, by reflow processing of solder balls placed on the surface treatment layer 66 or applied solder paste. As the solder ball, it is possible to use a spherical body in which the surface of a resin or metal core is covered with a conductive material.

  When solder balls are used, the height and volume (amount of solder) of the plurality of solder bumps 68 can be made uniform. This makes it possible to improve the yield and reliability in the mounting of the semiconductor chip 50 using the solder bumps 68.

  The surface treatment layer 67 is provided with solder bumps (not shown) as external connection terminals used when mounting the wiring substrate 60 on a mounting substrate such as a mother board. In addition, a solder ball, a lead pin, a stud bump, etc. can also be used as an external connection terminal.

  The semiconductor chip 50 is connected to the wiring substrate 60 by bonding the bumps 52 disposed on the element forming surface (lower surface in the drawing) of the semiconductor chip 50 and the solder bumps 68 formed on the wiring substrate 60 to each other. Electrically connected to layer 62. That is, the semiconductor chip 50 is flip-chip mounted on the wiring substrate 60. In the following description, reference numerals may be omitted for some members included in the semiconductor chip 50 and the wiring substrate 60.

Next, the head unit 15 for holding the above-described semiconductor chip 50 will be described.
As shown in FIG. 2, the base 21 of the head unit 15 is fixed to the side surface 14 a (the front surface in FIG. 1 (b)) of the frame 14. The Z-axis motor 22 is attached to the lower surface 21 a of the base 21. Z-axis motor 22 is, for example, a servomotor. The Z-axis motor 22 (output shaft) is connected to the ball screw 23. The ball screw 23 is screwed into the elevating base 24.

  The lift base 24 is supported by a guide 25 fixed to the side of the frame 14. The guide 25 supports the elevating base 24 so as to be vertically movable and non-rotatable. By driving the Z-axis motor 22, the ball screw 23 rotates forward and reverse. For example, the lift base 24 supported by the guide 25 is moved upward by the forward rotation of the ball screw 23, and the lift base 24 is moved downward by the reverse rotation of the ball screw 23.

  A load cell 26 is attached to the lower end of the lifting base 24. The load cell 26 outputs a signal of a value (level) according to the expansion and contraction in the Z-axis direction (vertical direction). For example, when the semiconductor chip 50 (electronic component) shown in FIG. 4 is pressed against the solder bump 68 of the wiring substrate 60, the semiconductor chip 50 is shrunk by the reaction force received from the wiring substrate 60 (solder bump 68). The load cell 26 outputs a signal having a value corresponding to the compression force (reaction force). That is, the load cell 26 outputs a signal according to the load in mounting of the electronic component (semiconductor chip 50).

A heat insulating member 27 is attached to the lower surface of the load cell 26. The tool suction portion 28 is attached to the lower surface of the heat insulating member 27.
In the tool suction portion 28, a tip holding hole 28a and a tool suction hole 28b are formed. The chip holding hole 28 a and the tool suction hole 28 b are an example of a flow path. The tip holding hole 28 a and the tool suction hole 28 b are formed, for example, by vertically penetrating the tool suction portion 28.

  A holding tool 29 is disposed below the tool suction unit 28. A gas is sucked from a tool suction hole 28b of the tool suction portion 28 by a vacuum pump 33 described later. Therefore, the inside of the tool suction hole 28 b is under negative pressure, and the negative pressure causes the tool suction unit 28 to hold the holding tool 29 by suction.

  In addition, the tool suction unit 28 has a heater function. Tool adsorption portion 28 includes, for example, a ceramic heater. The heat insulating member 27 blocks the heat conduction from the tool suction unit 28 to the load cell 26.

  The holding tool 29 is, for example, Bernoulli chuck. In the holding tool 29, a chip holding hole 29a is formed. The chip holding hole 29a is an example of a flow path. The tip holding hole 29a is set to a negative pressure by a vacuum pump 34 described later. The holding tool 29 sucks and holds the electronic component (the semiconductor chip 50 shown in FIG. 4) by the negative pressure.

  Further, the chip holding hole 29a is set to a positive pressure by air supplied by an air supply pump 35 described later. The tip holding hole 29 a is formed to radially discharge the air supplied by the air supply pump 35 along the lower surface of the holding tool 29. The holding tool 29 holds the electronic component (the semiconductor chip 50 shown in FIG. 4) in a noncontact manner by the Bernoulli effect generated by the discharged air. In the center of the lower surface 29 b of the holding tool 29, a vacuum region is generated by the air supplied by the air supply pump 35. This holds the electronic component. Such holding of electronic components is sometimes called Bernoulli adsorption.

Next, the electrical configuration of the electronic component mounting apparatus 10 will be described.
As shown in FIG. 3, the electronic component mounting apparatus 10 has a control device 31.
Connected to the control device 31 are a chip transfer robot 17, an XY stage 13, a Z-axis motor 22, a load cell 26, a camera 32, a vacuum pump 33, a vacuum pump 34, an air supply pump 35, a switching valve 36 and a heater 37. It is done.

  The control device 31 controls the chip transfer robot 17 to transfer the semiconductor chip 50 on the chip table 16 shown in FIG. 1A to the head unit 15. Then, the control device 31 sucks and holds the semiconductor chip 50 on the holding tool 29 shown in FIG. 2 by air suction by the vacuum pump 34.

  The control device 31 controls the XY stage 13 based on the image data obtained by photographing the semiconductor chip 50 and the wiring substrate 60 shown in FIG. 4 by the camera 32, and aligns the wiring substrate 60 with the semiconductor chip 50.

  As shown in FIG. 5, the camera 32 is, for example, a two-view camera (indicated by an arrow in the direction of the field of view), and moves in the horizontal direction (horizontal direction in FIG. 5). The control device 31 inserts and extracts the camera 32 between the semiconductor chip 50 held by the holding tool 29 and the wiring substrate 60 held by the XY stage 13.

  The controller 31 inserts the camera 32 between the semiconductor chip 50 and the wiring substrate 60. The camera 32 outputs, to the control device 31, image data obtained by shooting the upper semiconductor chip 50 and image data obtained by shooting the lower wiring board 60. The control device 31 controls the XY stage 13 based on the two image data to align the wiring substrate 60 with the semiconductor chip 50. For example, the control device 31 performs image processing on two image data, detects relative positional deviation between the semiconductor chip 50 and the wiring substrate 60 (displacement amount of X axis, Y axis, θ axis), and detects the detection result The X-Y stage 13 is controlled to reduce positional deviation based on that. Then, the control device 31 extracts the camera 32 from between the semiconductor chip 50 and the wiring substrate 60.

The control device 31 shown in FIG. 3 controls the Z-axis motor 22 to press the bumps 52 of the semiconductor chip 50 shown in FIG. 4 against the solder bumps 68 of the wiring substrate 60.
The load cell 26 outputs a signal according to the load in the Z-axis direction, that is, the pressing direction of the electronic component on the wiring substrate 60. The control device 31 detects a load (pressing force) on the electronic component (semiconductor chip 50 shown in FIG. 4) based on the output signal of the load cell 26. The control device 31 determines the pressed state of the electronic component (semiconductor chip 50) and the state (melting) of the solder bumps 68 based on the detected load. Then, the control device 31 controls the XY stage 13, the Z-axis motor 22, the switching valve 36, and the like based on the determination result. Details of this control will be described later.

  The vacuum pump 33 is connected to the tool suction hole 28b of the tool suction unit 28 shown in FIG. The controller 31 drives the vacuum pump 33 to hold the holding tool 29 in the tool suction unit 28 by vacuum suction. The controller 31 stops the vacuum pump 33 when the holding tool 29 is replaced.

  The vacuum pump 34 is connected to the tip holding hole 28 a of the tool suction unit 28 shown in FIG. 2 via the switching valve 36. The tip holding hole 28a is connected to the air supply pump 35 via the switching valve 36 shown in FIG.

  As shown in FIG. 2, the tip holding hole 28 a of the tool suction portion 28 communicates with the tip holding hole 29 a of the holding tool 29. Therefore, the tip holding hole 29a of the holding tool 29 is connected to the vacuum pump 34 or the air supply pump 35 via the switching valve 36 shown in FIG.

  The control device 31 controls the switching valve 36 to control air suction by the vacuum pump 34 and supply of air by the air supply pump 35 to the holding tool 29 shown in FIG. 2. The air supply pump 35 has, for example, a heater function to adjust the temperature of the supplied air. For example, the air supply pump 35 supplies hot air (hot air) to the holding tool 29 shown in FIG.

  The controller 31 sucks and holds the electronic component (the semiconductor chip 50 shown in FIG. 4) on the holding tool 29 by air suction. For example, the control device 31 holds the semiconductor chip 50 transferred by the chip transfer robot 17 with the holding tool 29. Further, the control device 31 holds the semiconductor chip 50 in a non-contact manner on the holding tool 29 by air supply. That is, the semiconductor chip 50 is separated from the lower surface 29 b of the holding tool 29 and is held at a predetermined distance from the lower surface 29 b. Therefore, the semiconductor chip 50 moves in the vertical direction according to the vertical movement of the holding tool 29. Also, the semiconductor chip 50 can freely move horizontally along the lower surface 29 b of the holding tool 29.

  The controller 31 controls the heater 37 to turn on and off. The heater 37 is included in the tool suction unit 28 shown in FIG. The heater 37 turned on generates heat. The heat of the heater 37 is transferred to the semiconductor chip 50 (see FIG. 4) adsorbed and held by the tool suction unit 28 shown in FIG. Further, the bumps 52 of the semiconductor chip 50 are transferred to the pressed solder bumps 68, and the solder bumps 68 are melted.

FIG. 6 shows the flow of processing carried out by the control device 31 (see FIG. 3) in component mounting.
In FIG. 6, the horizontal axis is time. FIG. 6 shows a state after the semiconductor chip 50 is pressed against the wiring substrate 60 (solder bump 68). In addition, in FIG. 6, although it does not show about members, such as an electronic component mounting apparatus, each member is demonstrated using the code | symbol shown to a related figure.

That is, the control device 31 sucks and holds the semiconductor chip 50 on the holding tool 29 by vacuum suction. Therefore, the semiconductor chip 50 is fixed horizontally and does not move.
Further, the control device 31 controls the Z-axis motor 22 so as to press the semiconductor chip 50 against the solder bumps 68 of the wiring substrate 60 with a predetermined pressing force. Therefore, the control device 31 detects the pressure (high pressure) at which the semiconductor chip 50 is pressed against the wiring substrate 60 as the detection pressure.

  The controller 31 turns on the heater 37 at time t1. The heat generation of the turned-on heater 37 heats the solder bumps 68 of the wiring substrate 60. The timing at which the heater 37 is turned on is not limited to this time t1. For example, when lowering the semiconductor chip 50, the heater 37 may be turned on immediately after or during the alignment.

  When the solid (solid phase) solder bump 68 changes to a liquid (liquid phase state), that is, the solder bump 68 melts, the reaction force of the solder bump 68 to the pressing force of the semiconductor chip 50 decreases. Therefore, the detected pressure is reduced (pressure is low). The controller 31 determines the melting of the solder bump 68 based on the decrease in the detected pressure (time t2). For example, the controller 31 determines melting of the solder bump 68 based on the detected pressure based on the output signal of the load cell 26 or the comparison result of the detected pressure and the set value.

  For example, the value of the output signal of the load cell 26 increases with the change in the compression direction of the load cell 26 based on the load, and decreases with the change in the extension direction. The controller 31 detects the size of the load based on the value of the output signal of the load cell 26. Then, the control device 31 compares the magnitude of the detected load with the setting value stored in the memory or the like, and presses the electronic component onto the solder bumps 68 (see FIG. 8) of the wiring substrate 60 with a desired load. Further, the control device 31 determines that the solder bump 68 is melted when the detected load decreases to a predetermined value (or when the detected load becomes smaller than the threshold value).

  For example, the control device 31 sets a load detected at the start of mounting of one electronic component (when mounting the electronic component received from the chip transfer robot 17 shown in FIG. 3) as an initial value, and changes from the initial value Let the amount (difference value) be the detected load.

  Then, when the solder bumps 68 are melted (the solder is in a liquid state), the control device 31 changes the method of holding the semiconductor chip 50 from adsorption holding (vacuum adsorption) to non-contact holding (Bernoulli adsorption). The control device 31 controls the switching valve 36 shown in FIG. 3 and supplies air to the holding tool 29 shown in FIG.

  Further, the control device 31 controls the Z-axis motor 22 to control the height of the holding tool 29. The holding tool 29 holds the semiconductor chip 50 by noncontact holding. Therefore, the control device 31 controls the height of the semiconductor chip 50. For example, the control device 31 drives and controls the Z-axis motor 22 based on the output signal of the load cell 26 so that the detected pressure becomes a predetermined value.

Then, the control device 31 turns off the heater 37 at time t3 after a predetermined time (for example, 3 seconds) has elapsed after switching the holding state.
Then, when the solder bumps 68 become solid (solid phase state), the control device 31 ends the process (time t4).

Next, the operation of the electronic component mounting apparatus 10 described above will be described.
As shown in FIG. 7, the semiconductor chip 50 is held by suction on the holding tool 29 by air suction from the chip holding hole 29a of the holding tool 29 by the vacuum pump 34 shown in FIG. In this state, as shown in FIG. 5, the wiring substrate 60 is aligned with the semiconductor chip 50 using the camera 32.

  As shown in FIG. 8, the semiconductor chip 50 adsorbed and held by the holding tool 29 is lowered, and the bumps 52 of the semiconductor chip 50 press the solder bumps 68 of the wiring substrate 60. The pressing force is detected as a load by the load cell 26 shown in FIG. The detected load causes contact between the bumps 52 and the solder bumps 68 to be detected. Therefore, the solder bumps 68 are not crushed by an excessive pressing force.

  Then, the heater 37 (see FIG. 3) is turned on to heat the solder bumps 68 through the holding tool 29 and the semiconductor chip 50. Then, the melting of the solder bumps 68 is determined based on the load detected by the load cell 26 shown in FIG. 3, and the holding state of the semiconductor chip 50 is switched from suction holding (vacuum suction) to noncontact holding (Bernoulli suction).

  As shown in FIG. 9, in non-contact holding, air supplied to the holding tool 29 is jetted radially along the lower surface of the holding tool 29 as indicated by the arrow. The upper surface of the semiconductor chip 50 is slightly separated from the lower surface of the holding tool 29. Due to this separation, there is no frictional resistance between the semiconductor chip 50 and the holding tool 29. Therefore, the semiconductor chip 50 freely moves in the horizontal direction (left and right direction and front and back direction in FIG. 9). Then, the bumps of the semiconductor chip 50 are so-called self-aligned in which they are drawn to a position corresponding to the solder bumps 68 (surface treatment layer 66) by the surface tension of the melted solder bumps 68. Therefore, as shown in FIGS. 7 and 8, even if the position of the solder bump 68 of the wiring substrate 60 is shifted with respect to the bump 52 of the semiconductor chip 50, the position of the solder bump 68 (surface treatment layer 66) by self alignment. The bumps 52 are drawn into. Therefore, in the alignment of the wiring substrate 60 with the semiconductor chip 50, it is not necessary to perform the alignment with high accuracy. In other words, an inexpensive stage with low accuracy can be used as the X-Y stage 13 shown in FIG.

  The heater 37 is turned off to harden the solder bumps 68. The wiring substrate 60 is held by suction on the XY stage 13 shown in FIG. Thereby, deformation such as warpage of the wiring board 60 due to reflow is suppressed. The holding tool 29 holds the semiconductor chip 50 in a noncontact manner until the solder bumps 68 are cured. Therefore, the semiconductor chip 50 is held in parallel to the wiring substrate 60. Therefore, the semiconductor chip 50 is not inclined and fixed to the wiring substrate 60 due to the floating of the semiconductor chip 50 or the like. Thereby, the occurrence of contact failure between the bumps 52 and the solder bumps 68 is suppressed.

  Further, the control device 31 holds the semiconductor chip 50 on the holding tool 29 in a noncontact holding manner, and controls the Z-axis motor 22 to control the height of the semiconductor chip 50. For example, the control device 31 controls the Z-axis motor 22 so as to set the load of the semiconductor chip 50 to a predetermined value based on the output signal of the load cell 26. Thereby, by controlling the height of the semiconductor chip 50, the shape (fillet etc.) of the solder bump 68 is controlled, and a good connection state can be obtained. In addition, the semiconductor chip 50 is lowered to prevent the solder bumps 68 from being hardened in a crushed state.

  As shown in FIG. 10, the semiconductor chip 50 is mounted on the wiring substrate 60 by the cured solder bumps 68. Thus, a semiconductor device in which the semiconductor chip 50 is mounted on the wiring substrate 60 can be obtained by the above-described process.

Next, a comparative example will be described. In addition, in description of a comparative example, it demonstrates using the same code | symbol as the said embodiment.
FIGS. 12 (a) to 12 (d) show the outline of the batch reflow (mass reflow) process.

  First, as shown in FIG. 12A, the semiconductor chip 50 is held by suction (vacuum suction) by the suction tool 100. Next, as shown in FIG. 12B, the semiconductor chip 50 is placed on the wiring substrate 60. The semiconductor chip 50 and the wiring substrate 60 are carried into a reflow furnace, and the solder bumps 68 are melted collectively. Thereafter, as shown in FIG. 12C, the semiconductor chip 50 is mounted on the wiring substrate 60 by the molten solder bumps 68 being cooled and solidified as the wiring substrate 60 taken out from the reflow furnace is cooled. .

  However, in this reflow method, there is a possibility that the positional displacement of the semiconductor chip 50 or the semiconductor chip 50 may drop from above the wiring substrate 60 when being transferred to the reflow furnace. Further, as shown in FIG. 12D, the solder bumps 68 may be solidified in a state where the semiconductor chip 50 is inclined with respect to the wiring substrate 60. In this case, some of the bumps 52 are separated from the solder bumps 68, that is, connection failure occurs. In the reflow furnace, the wiring substrate 60 may be deformed such as warpage. Also in this case, a connection failure may occur as in the state shown in FIG.

13 (a) and 13 (b) show an outline of the process of individual reflow (local reflow).
First, as shown in FIG. 13A, the semiconductor chip 50 is held by suction (vacuum suction) by the suction tool 100. Next, as shown in FIG. 13B, the bumps 52 of the semiconductor chip 50 are pressed against the solder bumps 68 of the wiring substrate 60 to heat and melt the solder bumps 68, and then the suction is released. Then, the solder bumps 68 may be crushed and solidified due to the expansion of the wiring substrate 60, the warpage generated in the semiconductor chip 50, and the like. In this case, the mounting strength of the semiconductor chip 50 on the wiring substrate 60 may not be obtained. In addition, the solder bumps 68 may protrude to the side due to the crushing, and a short circuit failure may occur in contact with the adjacent solder bumps 68.

FIG. 11 shows a process in the case where the semiconductor chip 50 is held by suction until the solder bumps 68 are solidified by vacuum suction.
In this case, the semiconductor chip 50 is held by the suction tool 100 (see FIG. 13A) by vacuum suction. Then, the solder bumps 68 solidify in this held state. Therefore, it is necessary to align the semiconductor chip 50 and the wiring substrate 60 with high accuracy. A stage that performs alignment with such high accuracy is expensive. In addition, since the alignment takes time, the throughput in the manufacturing process is reduced and the manufacturing cost is increased.

As described above, according to this embodiment, the following effects can be obtained.
(1) The electronic component mounting apparatus 10 has an XY stage 13 for holding the wiring substrate 60, a head unit 15, and a control device 31. The head unit 15 includes a holding tool 29 for holding the semiconductor chip 50 and a heater 37 for heating the holding tool 29. The head unit 15 is disposed above the XY stage 13 and moves the holding tool 29 in the vertical direction.

  The control device 31 sucks gas from the flow path of the holding tool 29 and presses the bumps 52 of the semiconductor chip 50 adsorbed and held against the solder bumps 68 of the wiring substrate 60, and the heater 37 causes the holding tool 29 and the semiconductor chip 50 to intervene. The solder bumps 68 are heated. Then, the control device 31 holds the semiconductor chip 50 after melting the solder bumps 68 and discharges a gas between the holding tool 29 and the semiconductor chip 50 from the flow path of the holding tool 29 and sends the gas to the holding tool 29. Switch to non-contact holding.

  The semiconductor chip 50 held by the holding tool 29 in a noncontact holding manner is held parallel to the wiring substrate 60 by the holding tool 29. Therefore, the semiconductor chip 50 is not inclined and fixed to the wiring substrate 60 due to the floating of the semiconductor chip 50 or the like. As a result, the occurrence of contact failure between the bumps 52 and the solder bumps 68 can be suppressed, and a decrease in reliability can be suppressed.

  (2) The semiconductor chip 50 held by the holding tool 29 in non-contact holding can freely move along the lower surface 29 b of the holding tool 29, that is, in the horizontal direction. For this reason, the bumps of the semiconductor chip 50 are so-called self-aligned in which the surface tension of the melted solder bumps 68 is drawn to a position corresponding to the solder bumps 68 (surface treatment layer 66). Therefore, in the alignment of the wiring substrate 60 with the semiconductor chip 50, it is not necessary to perform the alignment with high accuracy. In other words, an inexpensive stage with low accuracy can be used as the X-Y stage 13 shown in FIG.

  (3) The head unit 15 has a load cell 26. The controller 31 detects the load applied to the semiconductor chip 50 based on the output signal of the load cell 26. The controller 31 presses the bumps 52 of the semiconductor chip 50 against the solder bumps 68 of the wiring substrate 60 based on the detected load. Thus, the bumps 52 of the semiconductor chip 50 can be reliably pressed against the solder bumps 68 of the wiring substrate 60.

  (4) The controller 31 determines the melting of the solder bumps 68 based on the output signal of the load cell 26, and switches the holding of the electronic components from suction holding to noncontact holding after the solder bumps 68 are melted. In the non-contact holding, since the gas (hot air) is discharged from the holding tool 29, there is a possibility that an extra force is applied to the semiconductor chip 50, or positional deviation of the semiconductor chip 50 may occur due to the discharged gas. On the other hand, in the present embodiment, by switching from suction holding to non-contact holding after melting the solder bumps 68, it is possible to suppress the application of an extra load or the like to the semiconductor chip 50 and the positional deviation.

  (5) The control device 31 controls the height of the holding tool based on the output signal of the load cell 26 after switching the holding of the semiconductor chip 50 to the non-contact holding. Thereby, by controlling the height of the semiconductor chip 50, the shape (fillet etc.) of the solder bump 68 is controlled, and a good connection state can be obtained. In addition, it is possible to prevent the semiconductor chip 50 from falling and hardening in a state where the solder bumps 68 are crushed, and to suppress the occurrence of a short circuit or the like.

  (6) The head unit 15 includes a tool suction unit 28 having a tool suction hole 28 b connected to the vacuum pump 33. The tool suction unit 28 sucks and holds the holding tool 29 by vacuum suction. Therefore, the holding tool 29 for holding the electronic component can be easily replaced according to the electronic component.

The above embodiments may be implemented in the following manner.
In the above embodiment, the melting state of the solder bump 68 is determined based on the output signal of the load cell 26, and the holding state of the semiconductor chip 50 is switched from adsorption holding to non-contact holding. On the other hand, the holding state of the semiconductor chip 50 may be switched after a predetermined time (for example, one second) elapses after determining the melting of the solder bumps 68. Alternatively, the control device 31 may include a timer function to measure the elapsed time since the heater 37 is turned on, and switch the holding state of the semiconductor chip 50 after a predetermined time has elapsed. The time from the start of heating to the melting of the solder bump 68 is measured in advance and stored in the control device 31 as a predetermined time. Even in this case, the same effect as the above embodiment can be obtained.

  In the above embodiment, the hot air is supplied to the holding tool 29 from the air supply pump 35, but the temperature may be adjustable. For example, by supplying cold air after the heater 37 is turned off, the solder bumps 68 can be solidified in a short time.

  The movement of the XY stage 13 and the head unit 15 may be changed as appropriate in the above embodiment. For example, the stage may be moved to the X axis and the Y axis, and the head unit 15 may move the Z axis and move (rotate) the θ axis. 1A, the head unit 15 is moved along the frame 14 in the horizontal direction (left and right direction in FIG. 1A), and the stage is vertically moved in the direction orthogonal to the frame 14 (FIG. 1A). Direction) and the θ axis.

  A sealing resin (underfill resin) may be filled between the wiring substrate 60 and the semiconductor chip 50. The sealing resin is, for example, an insulating resin such as an epoxy resin. The sealing resin improves the connection strength of the connection portion between the bump 52 and the solder bump 68. Further, the sealing resin suppresses the occurrence of corrosion and electromigration of the wiring pattern of the wiring substrate 60, and prevents the reduction in reliability. Therefore, the semiconductor chip 50 may be mounted on the wiring substrate using the wiring substrate on which the sealing resin is applied on the upper surface.

In the above embodiment, the gas supplied to the holding tool 29 by the air supply pump 35 may be, for example, an inert gas.
In the above embodiment, the head unit 15 including the heater 37 is used. However, the heater 37 may not be included in the head unit 15 as long as it can heat the bumps 68 of the wiring substrate 60. For example, the solder bumps 68 may be directly heated using a heater that discharges hot air. The solder bumps 68 of the wiring substrate 60 and the bumps 52 of the semiconductor chip 50 may be heated by a heater.

DESCRIPTION OF SYMBOLS 10 electronic component mounting apparatus 13 stage 15 head part 28 tool adsorption | suction part 29 holding tool 31 control apparatus 37 heater 50 semiconductor chip (electronic component)
52 Bump (connection terminal)
60 wiring board 68 solder bump

Claims (9)

An electronic component mounting apparatus for mounting an electronic component on a wiring board, comprising:
With the heater,
A stage for holding the wiring board;
A head unit including a holding tool for holding the electronic component, disposed above the stage, and moving the holding tool in the vertical direction;
A controller that controls the heater and the head unit;
Have
The control device presses a connection terminal of the electronic component, which sucks and sucks gas from the flow path of the holding tool, onto the solder bump of the wiring substrate, heats the solder bump by the heater, and the solder bump Between the holding tool electronic component and the electronic component by discharging the gas between the holding tool and the electronic component from the flow path of the holding tool after melting of Switch to non-contact holding to create a vacuum region and hold the electronic component in a non-contact manner, and self-align the electronic component by surface tension of the melted solder bump in a non-contact holding state of the electronic component Electronic component mounting apparatus characterized in that The holding tool discharges the gas radially along the lower surface of the holding tool to create a vacuum region at the center of the lower surface and hold the electronic component in a noncontact manner. The electronic component mounting apparatus according to claim 1, characterized in that The head unit includes a load detection sensor that detects a load applied to the electronic component,
The control device is configured to press the connection terminal of the electronic component against the solder bump of the wiring substrate based on the output signal of the load detection sensor.
The electronic component mounting apparatus according to claim 1 or 2, characterized in that The head unit includes a load detection sensor that detects a load applied to the electronic component,
The control device determines melting of the solder bump based on an output signal of the load detection sensor, and switches the holding of the electronic component from the suction holding to the non-contact holding after the melting of the solder bump. The electronic component mounting apparatus according to claim 1 or 2 , characterized in that: The control device has a timer function, measures an elapsed time after turning on the heater, and based on the measurement result, holds the electronic component from the adsorption holding after the setting time elapses based on the measurement result from the suction holding The electronic component mounting apparatus according to any one of claims 1 to 3, characterized in that the switching is performed. Wherein the control device, after switching to the non-contact holding the holding of the electronic component, to control the height of the holding tool based on an output signal of the load detection sensor, to claim 3 or 4, characterized in Electronic component mounting apparatus as described.   The said head part has a tool adsorption | suction part which carries out adsorption | suction holding of the said holding | maintenance tool, The electronic component mounting apparatus as described in any one of Claims 1-6 characterized by the above-mentioned. The heater is included in the head unit,
Heating the solder bumps via the holding tool and the electronic component by the heater;
The electronic component mounting apparatus as described in any one of the Claims 1-7 characterized by these. An electronic component mounting method for mounting an electronic component on a wiring board, comprising:
The holding tool of the head unit disposed above the stage holding the wiring substrate sucks gas from the flow path of the holding tool to hold the electronic component by suction.
Pressing the connection terminal of the electronic component against the solder bump of the wiring substrate held by the stage;
Heating the solder bumps by a heater;
After melting the solder bumps, the holding of the electronic component is carried out, the gas is discharged between the holding tool and the electronic component from the flow path of the holding tool, and the electronic component is held in a noncontacting manner by the holding tool. of contact with the switch to retain the state in which the electronic component and the non-contact holding, mounting method of electronic components, characterized in that, you so that by self-alignment of the electronic component by the surface tension of the solder bumps melted to .