JP2008147555A - Soldering method and weight, and method for fabricating electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in thickness of solder at a bonding portion when a chip component is soldered onto a circuit board over the entire bonding surface. <P>SOLUTION: When a semiconductor element 12 is soldered to a metal circuit 13 provided on a circuit board 11, a weight 30 having a protrusion 30b for pressing a chip component and a protrusion 30c for regulating inclination is employed as the weight 30 for pressing the semiconductor element 12 to the metal circuit 13 side when the solder is melted. The semiconductor element 12 is arranged on the metal circuit 13 through a solder sheet 33 and the weight 30 is mounted such that the protrusion 30b for pressing a chip component presses the semiconductor element 12. The solder sheet 33 is melted while pressing the semiconductor element 12 with the weight 30, and the semiconductor element 12 is soldered to the metal circuit 13 under parallel state as the protrusion 30c for regulating inclination abuts against the metal circuit 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a soldering method, a weight, and an electronic device manufacturing method, and more particularly to a soldering method, a weight, and an electronic device manufacturing method for bonding a chip component such as a semiconductor element on a circuit board over the entire bonding surface. .

  Conventionally, a method using high frequency induction heating is known as a method of joining a metal member and a ceramic member, or a substrate and an electronic component (see, for example, Patent Document 1). Patent Document 1 proposes a joining apparatus that joins a plurality of thermoelectric elements and a substrate to manufacture a thermoelectric conversion module. As shown in FIG. 10A, the bonding apparatus includes a table 61, a pressurizing jig (weight) 63 that presses the substrate 62 while contacting the lower end surface of the substrate 62, and around the pressurizing jig 63. And a high-frequency heating coil 64 provided in the apparatus. Then, the carbon sheet 65, the thermoelectric element 66, and the substrate 62 are sequentially disposed on the table 61, and the pressurizing jig 63 is heated by induction heating (high frequency heating) in a state where the pressurizing jig 63 pressurizes the substrate 62. To do. Then, the heat of the pressing jig 63 is transmitted to the substrate 62, and the thermoelectric element 66 is bonded to the substrate 62. Also, soldering or brazing can be performed by placing solder or brazing material between the objects to be joined.

  Further, when mounting a semiconductor element or an electronic component on a circuit board, a method of joining the circuit board and the semiconductor element or the like via solder is common. When soldering a semiconductor element or the like on a circuit board, the position of the semiconductor element or the like may be shifted due to the surface tension of the molten solder when the solder intervening between the semiconductor element or the like and the circuit board is melted. In some cases, the solder is bonded to the entire bonding surface without spreading.

2. Description of the Related Art Conventionally, there has been proposed a soldering component lifting prevention jig that effectively prevents positional deviations such as tilting and lifting of electronic components to be soldered (see, for example, Patent Document 2). As shown in FIG. 10B, the anti-lifting jig is mounted on the printed circuit board 71 in the relay 72 so as to be able to be mounted on the printed circuit board 71 across the relay 72 mounted on the printed circuit board 71. A component pressing jig 75 having an electronic component receiving recess 75a with a depth corresponding to the height of the component is provided. The component pressing jig 75 is held at the mounting position on the printed circuit board 71 by its own weight. The electronic component housing recess 75 a is formed in a tapered shape that gradually expands toward the placement surface side of the printed circuit board 71. The circuit on the printed circuit board 71 side and each lead 72a are soldered by passing over the solder jetted by a soldering apparatus such as a flow solder. A clearance of about 0.1 mm is provided between the bottom surface 75 b of the electronic component housing recess 75 a and the top surface 72 b of the relay 72.
Japanese Utility Model Publication No. 5-13660 JP 2002-261433 A

  Placing a weight on a chip part (part to be soldered) during soldering helps spread the solder. However, when soldering is performed by melting the solder corresponding to the entire bonding surface of the chip component, depending on the type of solder, the surface facing the chip component of the solder protrudes upward due to the surface tension of the molten solder. The curved surface. Therefore, the weight placed on the semiconductor element is tilted, and the thickness of the solder existing between the semiconductor element and the bonding surface to which the semiconductor element is bonded is not uniform.

  When a cooling circuit board in which a ceramic board and a metal heat sink are integrated is used as the circuit board, if the thickness of the solder that joins the semiconductor element and the board varies, the variation in thickness may cause thermal resistance. Variation. As a result, there is a problem that the stress relaxation effect that absorbs the difference in the coefficient of linear expansion between the semiconductor element and the wiring layer that are joined via solder varies and the fatigue life of the thermal cycle varies.

  In Patent Document 1, no consideration is given to the problem at the time of melting the solder as described above. On the other hand, in Patent Document 2, a component pressing jig 75 is used for the purpose of effectively preventing misalignment such as inclination or lifting of an electronic component to be soldered. However, the electronic component is a lead component including the lead 72a, and only the method of transmitting the printed board 71 through the solder on which the solder is jetted is described. The main cause is vibration and shock during transportation. That is, no consideration is given to the above-described problem that occurs when soldering is performed by melting the solder corresponding to the entire bonding surface of the chip component.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to suppress unevenness in the thickness of the solder in the joint portion when the chip component is soldered on the circuit board over the entire joint surface. It is to provide a soldering method, a weight, and a method for manufacturing an electronic device.

  In order to achieve the above object, an invention according to claim 1 is a soldering method for soldering a chip component to a joint provided on a circuit board. As a weight that presses the chip component toward the joint when the solder is melted, a weight including a chip component pressurizing portion and an inclination regulating convex portion is used, and the chip component is placed on the joint via solder. And the weight is placed in a state in which the chip component pressing portion presses the chip component. Then, the solder is melted while pressing the chip component with the weight, and the chip component is soldered in a state parallel to the joint portion by the tilt regulating convex portion coming into contact with the circuit board.

  In this invention, a chip component is disposed on a joint provided on a circuit board via solder. Then, the solder is melted in the state in which the weight is placed on the circuit board in a state in which the chip component pressing portion presses the chip component. Since the melted solder tends to have a shape approaching a sphere due to surface tension, a force for lifting the chip component and the weight acts. Soldering is completed by cooling and solidifying the solder in a state where this force is balanced with the weight of the chip component and the weight (hereinafter sometimes referred to as the weight of the weight or the like). When the weight is simply placed on the chip component, the solder may solidify in a state where the joint portion of the circuit board and the joint surface of the chip component are not parallel to each other due to the balance. However, according to the present invention, the weight includes the chip component pressing portion and the tilt regulating convex portion, and therefore, in the melted state, the tip of the tilt regulating convex portion comes into contact with the circuit board, and the weight Is a state in which each chip component is pressed toward the bonding surface in a horizontal state or a substantially horizontal state. As a result, in a state where the solder is cooled below its melting temperature, soldering is performed in a state where the thickness unevenness of the solder at each joint is suppressed.

  According to a second aspect of the present invention, in the first aspect of the invention, when the weight is placed in a state in which the chip component pressure portion presses the chip component, the chip component pressure portion Is formed so that the center of gravity of the weight exists in a range surrounded by an imaginary line connecting the center of the projection and the center or end of the inclination regulating convex portion. In the present invention, when the total number of chip part pressing portions and inclination regulating convex portions is 3 or more, the weight is formed so that the center of gravity of the weight exists within the range surrounded by the imaginary line connecting the centers thereof. Therefore, in a state where the solder is melted, the tip of the inclination regulating convex portion comes into contact with the circuit board, and the weight presses each chip component toward the bonding surface in a horizontal state or a substantially horizontal state. . In addition, when the number of the chip component pressurizing portion and the inclination regulating convex portion is one, it is within a range surrounded by a virtual line connecting the center of the chip component pressurizing portion and both ends of the tilt regulating convex portion. The weight is formed so that the center of gravity of the weight exists. The tip surface of the chip component pressure part changes freely in the molten state of the solder, but the inclination regulating convex part makes contact with the circuit board on the surface, so the positions of both ends and the center position of the chip component pressure part Since the three points are determined, soldering is performed in a state where the uneven thickness of the solder at the joint is suppressed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the chip component pressing portion is formed so as to be capable of pressing the chip component in an area of more than half including its center. . Depending on the number of inclination regulating convex portions and the weight of the weight, the chip component pressing portion does not need to press the chip component on the entire surface. However, in the present invention, in the molten state of the solder, the chip component pressurizing portion presses the chip component to the joint portion side with an area of more than half including the center thereof, so that the uneven thickness of the solder at the joint portion is suppressed. Soldering is easily performed in the state.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, heat is transmitted to the solder through the weight to melt the solder. In the present invention, for example, the weight is heated by induction heating or a heater, and the heat is transmitted to the solder to melt the solder. Since soldering is preferably performed in a non-oxidized state, the circuit board is contained in a container and is performed in an inert gas or reducing gas atmosphere, which is more efficient than heating the entire circuit board or the entire container. Heating can be realized.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the circuit board, the solder layer, and the chip component are sequentially soldered. In this invention, the pressurization with the weight is favorably performed.

  A sixth aspect of the present invention is a weight used in the soldering method according to any one of the first to fifth aspects, wherein the weight includes at least one pressure surface, and a tip is formed from the pressure surface. Projecting convex portions are formed. The weight of the present invention uses the pressure surface as the chip part pressure portion, and uses a convex portion whose tip protrudes from the pressure surface as the inclination regulating convex portion, so that any one of claims 1 to 5 is used. It can use suitably for the soldering method of description.

  The invention described in claim 7 is an electronic device manufacturing method using the soldering method according to any one of claims 1 to 5 in a soldering process. In this invention, in the manufacturing method of an electronic device, there exists an effect | action and effect of the invention as described in the said corresponding claim.

  According to the present invention, when the chip component is soldered on the circuit board over the entire bonding surface, it is possible to suppress unevenness in the thickness of the solder at the bonding portion.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a method for soldering a semiconductor element, which is one step of a method for manufacturing a semiconductor module that is a component of an electronic device, will be described with reference to FIGS.

  As shown in FIGS. 1A and 1B, a semiconductor module 10 includes a circuit board 11 and a plurality (two) of semiconductor elements 12 as chip components joined to the circuit board 11 by soldering. I have. The circuit board 11 is a cooling circuit board (substrate with a heat sink) in which a ceramic substrate 14 as an insulator having a metal circuit 13 on the surface is integrated through a metal heat sink 15 and a metal plate 16. The heat sink 15 includes a refrigerant flow path 15a through which a cooling medium flows. The heat sink 15 is formed of aluminum metal, copper or the like. An aluminum-based metal means aluminum or an aluminum alloy. The metal plate 16 functions as a bonding layer for bonding the ceramic substrate 14 and the heat sink 15 and is formed of, for example, aluminum or copper.

  The metal circuit 13 is made of, for example, aluminum or copper. The ceramic substrate 14 is made of, for example, aluminum nitride, alumina, silicon nitride, or the like. The semiconductor element 12 is bonded (soldered) to the metal circuit 13. That is, the metal circuit 13 constitutes a joint for joining the semiconductor element 12 on the circuit board 11. A symbol “H” in FIG. 2 indicates a solder layer. As the semiconductor element 12, for example, an IGBT (Insulated Gate Bipolar Transistor) or a diode is used.

Next, a method for manufacturing a semiconductor module will be described.
FIG. 2 schematically shows the configuration of the soldering apparatus. As shown in FIG. 2, the soldering apparatus HK used for manufacturing the semiconductor module 10 includes a hermetically sealed container (chamber) 17, which includes a box-shaped main body 18 having an opening 18a, and the main body. And a lid 19 that opens and closes 18 openings 18a. The main body 18 is provided with a support base 20 that positions and supports the semiconductor module 10. The main body 18 is provided with a packing 21 at the mounting portion of the lid body 19.

  The lid body 19 is formed in a size capable of closing the opening 18 a of the main body 18, and the sealed space S is formed in the container 17 by attaching the lid body 19 to the main body 18. Yes. Further, in the lid 19, a portion facing the sealed space S is formed of an electrically insulating material that passes magnetic lines of force (magnetic flux). In this embodiment, glass is used as an electrical insulating material, and a glass plate 22 is assembled to the lid 19.

  The main body 18 is connected to a reducing gas supply unit 23 for supplying a reducing gas (hydrogen in this embodiment) into the container 17. The reducing gas supply unit 23 includes a pipe 23a, an opening / closing valve 23b of the pipe 23a, and a hydrogen tank 23c. The main body 18 is connected to an inert gas supply unit 24 for supplying an inert gas (nitrogen in this embodiment) into the container 17. The inert gas supply unit 24 includes a pipe 24a, an opening / closing valve 24b of the pipe 24a, and a nitrogen tank 24c. The main body 18 is connected to a gas discharge unit 25 for discharging the gas filled in the container 17 to the outside. The gas discharge unit 25 includes a pipe 25a, an opening / closing valve 25b of the pipe 25a, and a vacuum pump 25c. The soldering apparatus HK includes a reducing gas supply unit 23, an inert gas supply unit 24, and a gas discharge unit 25, so that the pressure in the sealed space S can be adjusted. The pressure is increased or decreased by pressure adjustment.

The main body 18 is connected to a heat medium supply unit (not shown) as supply means for supplying a heat medium (cooling gas) into the container 17 after soldering.
A high-frequency heating coil 26 is installed above the soldering device HK (above the lid 19). The high-frequency heating coil 26 of this embodiment is formed in a size that covers one ceramic substrate 14. The high frequency heating coil 26 is formed in a spiral shape (rectangular spiral shape) and is developed in a plane. Moreover, the high frequency heating coil 26 is arrange | positioned so that the cover body 19 (attachment part of the glass plate 22) may be opposed. The high-frequency heating coil 26 is electrically connected to a high-frequency generator 27 provided in the soldering apparatus HK, and based on the measurement result of a temperature sensor (not shown) installed in the container 17, the high-frequency generator 27 Output is controlled. The high-frequency heating coil 26 is formed with a cooling path 28 for passing cooling water through the coil, and is connected to a cooling water tank 29 provided in the soldering apparatus HK.

  A support plate 31 that can support a weight 30 that pressurizes the semiconductor element 12 when soldering is horizontally attached to the lid 19. The support plate 31 is formed of an insulating material (for example, ceramics) that allows passage of lines of magnetic force, and includes a hole 31 a that can be inserted below the flange portion 30 a of the weight 30. The weight 30 is mounted on the support plate 31 in a state of being inserted into the hole 31a. As shown in FIG. 2, in the state where the lid 19 is disposed at the closed position, the weight 30 abuts on the surface (non-bonded surface) opposite to the bonded surface of the semiconductor element 12, and the flange portion 30 a The weight 30 is lifted from the upper surface of the support plate 31, and the weight 30 presses the semiconductor element 12 with its own weight.

  The weight 30 includes a chip part pressing convex part 30b as a chip part pressing part and an inclination regulating convex part 30c. As shown in FIG. 2, the chip component pressing convex portion 30b is formed to have a size capable of contacting the entire upper surface of the semiconductor element 12 during soldering, and the tilt regulating convex portion 30c is formed during soldering. In FIG. 2, the metal circuit 13 is formed in a size capable of contacting. In the weight 30, the chip component pressing convex portion 30 b presses the semiconductor element 12 in a state where the solder is melted, and the inclination regulating convex portion 30 c abuts on the circuit board 11, so that the bonding surface of the semiconductor element 12 is a metal. It is formed in a shape and weight that can be held in parallel with the circuit 13. In this embodiment, since the semiconductor element 12 is disposed so as to be positioned at two corners on the diagonal line of the square ceramic substrate 14, as shown in FIGS. The convex portions 30b are arranged so as to be located at two corners on the diagonal of the planar square weight 30, and the inclination regulating convex portions 30c are arranged so as to be located at two corners on another diagonal. In addition, in Fig.3 (a), the external shape of the flange part 30a is shown with the dashed-two dotted line.

  The inclination regulating convex part 30c is formed longer than the chip part pressing convex part 30b. The lengths of the chip part pressurizing convex part 30b and the tilt restricting convex part 30c are the chip part pressurizing convex parts in a state where the tip surface of the tilt restricting convex part 30c is in contact with the metal circuit 13 in the molten state of solder. 30b is set to a length capable of pressing the semiconductor element 12 in a horizontal state. The solder solders the semiconductor element 12 in a melted state due to the weight of the weight 30, and thus the difference between the length of the chip component pressing convex portion 30b and the length of the regulating convex portion 30c. Is set smaller than the sum of the thickness of the solder sheet 33 before melting and the thickness of the semiconductor element 12. Further, the weight 30 has a center of gravity G of the weight 30 in a range surrounded by a virtual line L1 that connects the centers of the chip part pressing convex part 30b and the inclination regulating convex part 30c and the center of the inclination regulating convex part 30c. Is formed to exist.

  The weight 30 is formed of a material that can transfer heat to the solder via the weight 30 to melt the solder. In this embodiment, the weight 30 is formed using a material that generates a current due to a change in magnetic flux and generates heat due to its own electrical resistance, that is, a material capable of induction heating. The weight 30 of this embodiment is formed of stainless steel.

  Further, when performing soldering, a positioning jig 32 is used to position the solder sheet 33, the semiconductor element 12, and the weight 30 on the ceramic substrate 14. As shown in FIG. 3C, the jig 32 is formed in a planar square shape. As shown in FIG. 2 and FIG. 3C, the jig 32 has a square recess 32 a that can be engaged with the outer periphery of the metal circuit 13 on the back surface, and the size of the semiconductor element 12. A positioning hole 32b formed with a corresponding size and a positioning hole 32c formed with a size corresponding to the size of the restricting convex portion 30c are formed. In this embodiment, two holes 32b and 32c are formed. In FIG. 3C, the outer shape of the flange portion 30a and the outer shape of the metal circuit 13 are indicated by a two-dot chain line, and a part of the two-dot chain line indicating the outer shape of the metal circuit 13 overlaps the dotted line indicating the recess 32a. ing.

  Next, a method for soldering the semiconductor element 12 to the circuit board 11 in the soldering process, which is one process for manufacturing the semiconductor module 10, using the soldering apparatus HK will be described. Prior to soldering using the soldering apparatus HK, the circuit board 11 in which the ceramic substrate 14 having the metal circuit 13 and the heat sink 15 are integrated is prepared in advance.

  When soldering, first, the lid 19 is removed from the main body 18 and the opening 18a is opened. Then, as shown in FIG. 2, the circuit board 11 is placed on the support 20 of the main body 18 and positioned. Next, a jig 32 is placed on the ceramic substrate 14 of the circuit board 11, and the solder sheet 33 and the semiconductor element 12 are disposed in each hole 32 b of the jig 32. The jig 32 is placed on the ceramic substrate 14 in a state where the concave portion 32 a is positioned by engaging with the peripheral edge portion of the metal circuit 13. The solder sheet 33 is disposed between the metal circuit 13 and the semiconductor element 12.

  Next, the lid 19 is attached to the main body 18, the opening 18 a is closed, and the sealed space S is formed in the container 17. When the lid body 19 is attached to the main body 18, as shown in FIG. 2, the chip component pressing convex portion 30b side of the weight 30 is inserted into the hole 32b of the jig 32, and the regulating convex portion 30c is inserted into the hole 32c. It is. Then, the tip of the chip part pressing convex part 30b of the weight 30 comes into contact with the non-bonding surface (upper surface) of the semiconductor element 12, and the flange part 30a is separated from the upper surface of the support plate 31. The semiconductor element 12 is disposed in a state where the semiconductor element 12 is pressurized by the weight of the weight 30 while straddling the two semiconductor elements 12. In this state, the solder sheet 33, the semiconductor element 12, and the weight 30 are arranged on the ceramic substrate 14 in this order from the metal circuit 13 side.

  Next, the gas discharge unit 25 is operated to evacuate the container 17 and the inert gas supply unit 24 is operated to supply nitrogen into the container 17 so that the sealed space S is filled with the inert gas. . After this evacuation and supply of nitrogen are repeated several times, the reducing gas supply unit 23 is operated to supply hydrogen into the container 17, and the sealed space S is made a reducing gas atmosphere.

  Next, the high frequency generator 27 is operated, and a high frequency current is passed through the high frequency heating coil 26. Then, a high frequency magnetic flux passing through the corresponding weight 30 is generated in the high frequency heating coil 26, and an eddy current is generated in the weight 30 due to the passage of the magnetic flux. The weight 30 placed in the magnetic flux of the high-frequency heating coil 26 generates heat due to electromagnetic induction, and the heat is transmitted from the chip component pressing convex portion 30 b of the weight 30 to the semiconductor element 12. Then, on the solder sheet 33 placed on each joint portion of the circuit board 11, the heat generated in the weight 30 is concentrated (locally) via the chip component pressing convex portion 30 b of the weight 30 and the semiconductor element 12. ) And heated. As a result, the solder sheet 33 is melted by being heated to a temperature equal to or higher than the melting temperature by heat transmitted through the semiconductor element 12.

  When the solder sheet 33 is melted, the semiconductor element 12 may be inclined depending on the balance between the surface tension of the melted solder and the center of gravity of the semiconductor element 12. However, the weight 30 includes a regulating convex portion 30c in addition to the chip component pressing convex portion 30b, and the tip of the inclination regulating convex portion 30c is a metal circuit on the circuit board 11 in a state where the solder is melted. 13, the weight 30 is in a state of pressing each semiconductor element 12 toward the bonding surface in a horizontal state or a substantially horizontal state. As a result, in a state where the solder is cooled below its melting temperature, soldering is performed in a state where the thickness unevenness of the solder at each joint is suppressed. For example, when wiring is performed by wire bonding in a subsequent process to connect between the semiconductor elements 12 on the circuit board 11 and between the semiconductor elements 12 and the wiring, it is avoided that the wire bonding is hindered. The

  After the solder is completely melted, the high frequency generator 27 is stopped. The magnitude of the high-frequency current flowing through the high-frequency heating coil 26 is controlled based on the detection result of a temperature sensor (not shown) installed in the container 17. Further, the pressure in the container 17 (sealed space S) is increased and decreased in accordance with the progress of the soldering operation, and the atmosphere is adjusted.

  After the solder sheet 33 is completely melted, the cooling gas is supplied into the container 17 by operating the cooling medium supply unit. The cooling gas is blown toward the inlet or outlet of the refrigerant flow path 15a of the heat sink 15, and the cooling gas supplied into the container 17 flows around the refrigerant flow path 15a and the heat sink 15 to be soldered. The object (semiconductor module 10) is cooled. As a result, the molten solder is solidified by being cooled below the melting temperature, and joins the metal circuit 13 and the semiconductor element 12. In this state, the soldering is finished and the semiconductor module 10 is completed. Then, the lid 19 is removed from the main body 18, the jig 32 is removed, and the semiconductor module 10 is taken out from the container 17.

Therefore, according to this embodiment, the following effects can be obtained.
(1) In a soldering method in which the semiconductor element 12 is soldered to the metal circuit 13 provided on the circuit board 11 over the entire bonding surface, the weight 30 that presses the semiconductor element 12 toward the metal circuit 13 when the solder melts. The weight 30 provided with the convex part 30b for chip component pressurization, and the convex part 30c for inclination control is used. The semiconductor element 12 is disposed on the metal circuit 13 via solder, and the weight 30 is placed in a state where the chip component pressing convex portion 30b presses the semiconductor element 12. The semiconductor element 12 is parallel to the metal circuit 13 by melting the solder while pressing the semiconductor element 12 with the weight 30 and contacting the inclination regulating convex part 30c with the circuit board 11 (more precisely, the metal circuit 13). Solder to state. Therefore, in a state where the solder is cooled below its melting temperature, soldering is performed in a state where the thickness unevenness of the solder at each joint is suppressed.

  (2) When the weight 30 is placed in a state where the chip component pressing convex portion 30b presses the semiconductor element 12, the weight 30 is centered on the chip component pressing convex portion 30b and the center of the tilt regulating convex portion 30c. Are formed such that the center of gravity G of the weight 30 exists in the range surrounded by the virtual line L1 connecting the two. Therefore, in the molten state of the solder, the tip surfaces of the two inclination regulating convex portions 30c abut against the circuit board 11, and the weight 30 adds each semiconductor element 12 to the bonding surface side in a horizontal state or a substantially horizontal state. It will be in the state to press. As a result, when the semiconductor element 12 is soldered on the circuit board 11 over the entire bonding surface, the soldering is performed in a state in which the thickness unevenness of the solder at the bonding portion is reliably suppressed.

  (3) The chip component pressing convex portion 30b is formed so as to be capable of pressing the semiconductor element 12 in an area of more than half including the center thereof. Depending on the number of the inclination regulating convex portions 30 c and the weight 30, the chip component pressing convex portion 30 b does not need to press the semiconductor element 12 over the entire surface. However, in the melted state of the solder, since the chip component pressing convex portion 30b presses the semiconductor element 12 to the joint portion side with an area of more than half including the center thereof, the thickness unevenness of the solder at the joint portion is suppressed. Soldering is easy.

  (4) Since the soldering is preferably performed in a non-oxidized state, the circuit board 11 is accommodated in the container 17 and is performed in an inert gas or reducing gas atmosphere. Since the solder is melted by transmitting the heat, it is possible to achieve more efficient heating than the case where the entire circuit board 11 and the entire container 17 are heated.

  (5) The weight 30 is caused to generate heat by induction heating, and the solder sheet 33 disposed between the semiconductor element 12 and the metal circuit 13 is heated via the semiconductor element 12. Can convey heat. Therefore, efficient heating can be realized as compared with the case where the entire circuit board 11 and the entire container 17 are heated.

  (6) The circuit board 11, the solder sheet 33 (solder layer), and the semiconductor element 12 are laminated in this order, and soldering is performed with the weight 30 placed thereon. Therefore, the pressurization by the weight 30 is performed satisfactorily.

  (7) The weight 30 has a plurality of convex portions, that is, a chip component pressing convex portion 30b and a regulating convex portion 30c formed on one surface, and the chip component pressing convex portion 30b has a length of the regulating convex portion. It is formed shorter than the part 30c. That is, at least one of the plurality of protrusions is formed shorter than the other protrusions.

  (8) The weight 30 is provided with the flange part 30a (holding part). The weight 30 is attached to the lid body 19 and is inserted into the hole 31a of the support plate 31 in which the hole 31a is formed at a predetermined position, and the lower surface of the flange portion 30a is engaged with the upper surface of the support plate 31. It is supported by the support plate 31 in a state. Therefore, when the lid body 19 is attached to the main body 18, the weight 30 is automatically arranged at a predetermined position facing the semiconductor element 12, and when the lid body 19 is removed from the main body 18, the weight 30 automatically becomes the semiconductor element. 12 is arranged at a position separated from 12.

  (9) The solder sheet 33 and the semiconductor element 12 are arranged in a state of being positioned at a predetermined position on the ceramic substrate 14 via the jig 32. Therefore, when the configuration in which the weight 30 is attached to the support plate 31 with the above-described configuration is adopted, the weight 30 can be efficiently arranged at a position where the weight 30 is in contact with each semiconductor element 12.

(10) The high frequency heating coil 26 is disposed outside the container 17. Therefore, the configuration in which the support plate 31 that supports the weight 30 is supported by the lid 19 is simplified.
(11) Soldering is performed by the above-described method in the soldering process of the semiconductor element 12 which is one process of the manufacturing method of the semiconductor module 10 which is a component of the electronic device. Therefore, each effect described above can be obtained in the method for manufacturing an electronic device.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). The second embodiment is different in the configuration of the weight 30 and the jig 32, and the other configurations are basically the same as those in the first embodiment. Therefore, detailed description of the same parts is omitted.

  In this embodiment, the weight 30 is provided for each semiconductor element 12. As shown in FIG. 4B, the weight 30 includes one chip component pressing convex portion 30b and two regulating convex portions 30c. The weight 30 is formed in a substantially L shape corresponding to the detection of the metal circuit 13, and the chip component pressing convex portion 30b is formed at the corner portion of the weight 30, and the regulating convex portion 30c is formed at the end portion. Is formed. The jig 32 is formed with two holes 32b for inserting the chip component pressurizing convex portions 30b and four holes 32c for inserting the restricting convex portions 30c.

  Even when the semiconductor element 12 is soldered to the circuit board 11 using the weight 30 and the jig 32 of this embodiment, the circuit board 11 is disposed in the container 17 in the same manner as in the first embodiment. A jig 32 is placed on the ceramic substrate 14, and the solder sheet 33 and the semiconductor element 12 are disposed in each hole 32 b of the jig 32. When the lid 19 is closed, the semiconductor element 12 is pressed by each weight 30 as shown in FIG. Then, the high frequency generator 27 is operated, the weight 30 is heated at high frequency, and the solder is melted.

  The centers of the chip part pressing convex part 30b and the regulating convex part 30c of each weight 30 are not in a straight line, but in a range surrounded by a virtual line L1 connecting the centers of the chip part pressing convex part 30b and the regulating convex part 30c. The center of gravity of the weight 30 exists inside. Accordingly, in the molten state of the solder, the weight 30 is in a state of pressing each semiconductor element 12 toward the bonding surface in a horizontal state or a substantially horizontal state. As a result, in a state where the solder is cooled below its melting temperature, soldering is performed in a state where the thickness unevenness of the solder at each joint is suppressed.

In this embodiment, the following effects can be obtained in addition to the same effects as the effects (1) to (11) in the first embodiment.
(12) Since a plurality of weights 30 are provided, the total weight of the weights 30 can be reduced as compared with a configuration in which both the semiconductor elements 12 are pressed by one weight 30. The circuit board 11 is not limited to one ceramic substrate 14, and there is also a semiconductor module 10 configured by soldering a semiconductor element 12 on a circuit board 11 in which a plurality of ceramic substrates 14 are integrated with a heat sink 15. Therefore, if the ability is the same, it is advantageous that the total weight is light.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the tip surfaces of the plurality of restricting convex portions 30c are in contact with the metal circuit 13, and the positions of the tip surfaces of the chip component pressing convex portions 30b are set, and the solder layer H and the semiconductor element 12 after melting are set. This is largely different from the first and second embodiments in that the total thickness is set.

  As shown in FIG. 6, the weight 30 is formed in a planar square shape, four restricting convex portions 30 c are formed at the four corners of the weight 30, and two chip component pressing convex portions 30 b are respectively restricted. It is formed in a range surrounded by an imaginary line (not shown) connecting the outside of the convex portion 30c for use. The difference in length between the chip component pressing convex portion 30b and the regulating convex portion 30c is that the weight 30 presses the molten solder with its weight, and the leading end surfaces of the regulating convex portions 30c are all on the metal circuit 13. It is set to come into contact. Depending on the thickness and area of the solder sheet 33 to be used, an appropriate value of the difference in length between the chip component pressing convex portion 30b and the regulating convex portion 30c varies. Therefore, it is preferable to obtain and set an appropriate value of the difference in length between the chip component pressing convex portion 30b and the regulating convex portion 30c in an experiment.

  In this embodiment, before the solder sheet 33 is melted, the restricting convex portion 30 c is arranged in a state slightly separated from the metal circuit 13. When the solder is melted, the weights of the weights 30 bring the tip surfaces of the restricting convex portions 30c into contact with the metal circuit 13, and the weights 30 move the semiconductor elements 12 to the bonding surface side in a horizontal state. Pressurized. As a result, in a state where the solder is cooled below its melting temperature, soldering is performed in a state where the thickness unevenness of the solder at each joint is suppressed.

In this embodiment, the following effects can be obtained in addition to the effects (1) and (3) to (11) in the first embodiment.
(13) Since the thickness of the solder layer H after cooling is determined by the difference in length between the restricting convex portion 30c and the chip component pressing convex portion 30b, in the molten state as in the first and second embodiments. The weight of the weight 30 is more flexible than when the thickness is determined by the balance between the thickness of the solder and the difference in length between the regulating convex part 30c and the chip part pressing convex part 30b.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The weight 30 includes a chip component pressing portion and an inclination regulating convex portion 30c, and the weight 30 is in a state where the chip component pressing convex portion 30b presses the semiconductor element 12 disposed on the metal circuit 13 via solder. It is sufficient that the semiconductor element 12 can be soldered in a state parallel to the metal circuit 13 by placing the inclination restricting convex portion 30 c in contact with the circuit board 11 when the solder is melted by placing the solder. For example, when two semiconductor elements 12 are soldered on the ceramic substrate 14, as shown in FIG. 7A, a weight 30 provided with one chip component pressing convex portion 30b and one regulating convex portion 30c is provided. Two may be used. The weight 30 is formed such that the center of gravity of the weight 30 exists in a range surrounded by a virtual line L1 that connects the center of the chip component pressing convex portion 30b and both ends of the inclination regulating convex portion 30c. For example, the length of the regulating convex portion 30c in the direction orthogonal to the virtual line L1 connecting the centers of the chip component pressing convex portion 30b and the regulating convex portion 30c is approximately the same as the length of the semiconductor element 12 in the same direction. It is formed. In this case, the tip surface of the chip component pressurizing convex portion 30b can freely change its angle in the molten state of the solder, but the tilt regulating convex portion 30c is in contact with the circuit board 11 (more precisely, the metal circuit 13). Then, the center of gravity of the weight 30 exists in the range of the virtual line L1 connecting the three points of the both end positions and the center position of the chip component pressing convex portion. As a result, tilting of the weight 30 is suppressed, and soldering is performed in a state where unevenness in the thickness of the solder at the joint is suppressed.

  ○ As in the third embodiment, the molten solder is pressed by the weight 30 and the thickness (height) of the solder is determined by the difference in length between the regulating convex portion 30c and the chip component pressing convex portion 30b. 1), the number of the semiconductor elements 12 may be one. For example, as shown in FIG. 7B, the weight 30 is formed in a planar square shape, one chip component pressing convex portion 30b is formed at the center of the lower surface, and the restricting convex portions 30c are formed at the four corners. One may be formed.

  The jig 32 is not limited to the configuration in which the concave portion 32 a is placed on the ceramic substrate 14 in a state where the concave portion 32 a is positioned by engaging with the peripheral edge portion of the metal circuit 13. For example, as shown in FIG. 8, the peripheral surface of the recess 32 a may be configured to be engageable with the peripheral surface 14 a of the ceramic substrate 14. The thickness of the metal circuit 13 is compared with the thickness of the ceramic substrate 14. Since it is thin, it is easier to form the recess 32a if it can be engaged with the peripheral surface 14a.

  The weight 30 includes at least one pressing surface that functions as a chip component pressing portion, and it is only necessary to form a convex portion whose tip protrudes from the pressing surface as the tilt regulating convex portion. In other words, the chip component pressing portion is not limited to the chip component pressing convex portion 30b. For example, as shown in FIG. 9, using a weight 30 provided with a pressurizing surface 30d instead of the chip component pressurizing convex portion 30b and having a regulating convex portion 30c whose tip protrudes from the pressurizing surface 30d. Also good. In the case where the chip component pressurizing portion 30b is provided as the chip component pressurizing portion, the tip surface of the chip component pressurizing convex portion 30b becomes the pressurizing surface.

  The number of ceramic substrates 14 provided on the circuit board 11 is not limited to one and may be plural. When the number of ceramic substrates 14 provided on the circuit board 11 is one, a plurality of circuit boards 11 may be accommodated in the container 17 and soldered at the same time.

  The weight 30 may be configured to be placed on the circuit board 11 one by one without providing the flange portion 30a. However, the configuration in which the weight 30 is moved to the mounting position and the separated position while being supported by the support plate 31 by the flange portion 30a makes it easier to place the weight 30 at a predetermined position. In particular, when it is necessary to place a plurality of weights 30 on the circuit board 11 in one soldering, the weights 30 can be placed simultaneously and easily.

  ○ As the semiconductor element 12 (chip component), for example, a transistor and a diode generally have different thicknesses, so that weights 30 having different length differences between the chip component pressing convex portion 30b and the regulating convex portion 30c are prepared. In addition, an optimum weight 30 corresponding to the chip component to be soldered may be used.

  ○ Depending on the number of the inclination regulating convex portions 30c and the weight 30, the chip component pressing convex portion 30b does not need to press the chip component (semiconductor element 12) on the entire surface thereof. The tip surface 30b does not necessarily have to be the same size as the non-joint surface of the semiconductor element 12 to be pressed. However, in the case of the soldering method in which the thickness of the solder is regulated by the balance between the regulating convex portion 30c and the molten solder as in the first and second embodiments, the chip component pressing convex portion 30b. It is preferable that the chip component is formed to have a size that presses the chip part toward the joint portion in an area of more than half including its center. When the tip surface of the chip component pressurizing convex portion 30b presses the chip component toward the joint portion with an area of more than half including the center thereof, soldering can be easily performed in a state where the thickness unevenness of the solder at the joint portion is suppressed. Is called.

  When the weight 30 is moved in a state of being inserted into the hole 31 a of the support plate 31, the structure for hooking the weight 30 to the support plate 31 is not limited to the flange portion 30 a, but is hooked to the upper side surface of the weight 30. You may provide a some convex part as a part.

  The jig 32 is not limited to the configuration having the positioning function of the solder sheet 33, the semiconductor element 12, and the weight 30, and may have a configuration having only the positioning function of the solder sheet 33 and the semiconductor element 12.

  In the configuration in which the weight 30 is heated by induction heating and the solder is melted by the heat, the weight 30 is not limited to stainless steel but may be any material that can be induction heated. For example, instead of stainless steel, iron or graphite may be used. You may form and may comprise using two types of conductor materials from which heat conductivity differs.

The solder is not limited to a method of arranging the solder sheet 33 at a location corresponding to the joint portion of the metal circuit 13, but a solder paste may be applied to a location corresponding to the joint portion.
○ The heating method for heating the solder to the melting temperature or higher may be a method other than induction heating. For example, an electric heater may be provided in the container 17 to heat the solder.

The circuit board 11 may have a configuration in which the ceramic substrate 14 is integrated with the heat sink 15 that does not have the refrigerant flow path 15 a or a configuration that does not have the heat sink 15.
The lid 19 may be configured so as not to be removable from the main body 18, for example, an openable type.

  The lid 19 is preferably formed of an electrically insulating material at least at a portion facing the high-frequency heating coil 26, and may be formed of, for example, ceramics or resin instead of glass. Moreover, you may form the whole cover body 19 with the same electrical insulating material.

  (Circle) the high frequency heating coil 26 is good also as a structure arrange | positioned ranging over the some weight 30. FIG. In this case, the high-frequency current supply path and the cooling water supply path to the high-frequency heating coil 26 can be reduced, and the structure of the soldering apparatus HK can be further simplified.

  The electronic component bonded to the bonding portion (metal circuit 23) provided on the circuit board 11 is not limited to the one where the entire surface facing the bonding portion is bonded, but an electronic component such as a chip resistor or a chip capacitor. A terminal may be provided at both ends of the component, and each terminal may be joined to a different joint.

  O It is sufficient that the regulating convex portion 30c is in contact with the upper surface of the circuit board 11 during soldering so as to regulate the inclination of the weight 30, and is in contact with the metal circuit 13 to regulate the inclination of the weight 30. Not exclusively. For example, the configuration may be such that the regulating convex portion 30 c contacts the upper surface of the ceramic substrate 14.

  The restricting convex portion 30c is not limited to the shape in which the tip is in surface contact, but may be in the shape of point contact or line contact. For example, a shape in which a linear convex portion is formed at the tip of the regulating convex portion 30c or a shape in which a small convex portion is formed at the tip of the regulating convex portion 30c may be used.

(Circle) you may arrange | position the high frequency heating coil 26 in the container 17 (sealed space S).
The following technical idea (invention) can be understood from the embodiment.
(1) In the invention according to any one of claims 1 to 7, the weight is formed of a conductive material capable of induction heating.

(A) is a top view of the semiconductor module with one ceramic substrate, (b) is the sectional view on the AA line of (a). The schematic longitudinal cross-sectional view of the soldering apparatus used for the soldering method of 1st Embodiment. (A) is a schematic diagram which shows the relationship between a metal circuit, the convex part for chip | tip component pressurization, the convex part for regulation, (b) is a schematic perspective view of a weight, (c) is a schematic top view of a jig | tool. The second embodiment, (a) is a schematic cross-sectional view showing a state at the time of soldering, (b) is a schematic view showing the relationship between a metal circuit, a chip component pressing convex portion, a regulating convex portion, and the like. The schematic cross section which shows the state at the time of soldering in 3rd Embodiment. The schematic diagram which similarly shows the relationship between a metal circuit, the convex part for chip | tip component pressurization, the convex part for regulation, etc. (A) is a schematic diagram which shows the relationship between the weight in another embodiment, and a chip component, (b) is a schematic diagram which shows the relationship between the weight in another embodiment, and a chip component. The schematic cross section which shows the shape of the jig | tool of another embodiment. The model perspective view which shows the weight of another embodiment. (A) is sectional drawing which shows a prior art, (b) is a schematic cross section which shows another prior art.

Explanation of symbols

  H ... solder layer, G ... center of gravity, L1 ... virtual line, 11 ... circuit board, 12 ... semiconductor element as a chip component, 13 ... metal circuit as a junction, 30 ... weight, 30b ... as a pressure component for a chip component Chip component pressing convex portion, 30c... Restricting convex portion, 30d... Pressure surface as a chip component pressing portion.

Claims (7)

A soldering method for soldering a chip component to a joint provided on a circuit board,
As a weight that presses the chip component toward the joint when the solder is melted, a weight including a chip component pressurizing portion and an inclination regulating convex portion is used, and the chip component is placed on the joint via solder. And the weight is placed in a state where the chip component pressing portion presses the chip component, the solder is melted while pressing the chip component with the weight, and the tilt regulating convex portion is A soldering method comprising: soldering the chip component in a state parallel to the joint by contacting a circuit board.   The weight is a virtual connection between the center of the chip component pressurizing portion and the center or end of the tilt regulating convex portion when the chip component pressurizing portion is placed in a state of pressing the chip component. The soldering method according to claim 1, wherein the weight is formed so that the center of gravity of the weight exists in a range surrounded by a line.   3. The soldering method according to claim 1, wherein the chip component pressing portion is formed so as to be able to press the chip component in an area of half or more including a center thereof.   The soldering method according to claim 1, wherein heat is transmitted to the solder through the weight to melt the solder.   The soldering method according to any one of claims 1 to 4, wherein the soldering is performed in a state where the circuit board, the solder layer, and the chip component are laminated in this order.   A weight used in the soldering method according to any one of claims 1 to 5, wherein the weight is provided with at least one pressing surface, and a convex portion whose tip protrudes from the pressing surface is formed. A weight characterized by being.   6. A method for manufacturing an electronic device, wherein the soldering method according to claim 1 is used in a soldering process.

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