JP7628559B2 - Heating device and method for manufacturing soldered object - Google Patents

Description

This disclosure relates to a heating device and a method for manufacturing a solder-joined object, and in particular to a heating device and a method for manufacturing a solder-joined object that suppresses the occurrence of temperature unevenness in the heated object.

One type of soldering device that solders mounted components such as semiconductors to a board is a reflow device as shown below. This reflow device has a plate on which a workpiece can be placed, placed above a heater in which multiple rod-shaped infrared lamps are arranged in parallel horizontally, and a cooler having a cooling block protruding between adjacent infrared lamps. It also has an elevator that raises and lowers the lift pins that support the plate in the vertical direction. When cooling the workpiece, the plate is placed in a cooling position where the bottom surface of the plate contacts the top surface of the cooling block, and when heating the workpiece, the plate is placed in a heating position that is higher than the cooling position (see, for example, Patent Document 1).

Patent No. 7053939

When the workpiece is heated to a specified temperature (e.g., the reduction temperature in Patent Document 1) and then maintained at that specified temperature for a specified time (e.g., until the reduction process is completed), the temperature at the ends of the plate tends to drop more than at the center. Regarding the direction of the infrared lamp arrangement, it is possible to reduce the temperature difference between the ends and center of the plate when the temperature is maintained by increasing the current supplied to the infrared lamps closer to the ends of the plate to increase the amount of heat generated. However, in the longitudinal direction of the infrared lamps, there still exists a temperature difference between the ends and center that affects the process.

In view of the above-mentioned problems, the present disclosure relates to providing a heating device that suppresses temperature unevenness in an object to be heated and a method for manufacturing a solder-joined object.

The heating device according to the first aspect of the present disclosure includes a support member that supports an object to be heated, and a heater that radiates heat to the object to be heated supported by the support member or to the support member that supports the object to be heated, the heater having a heating tube that emits greater radiant energy at both ends than at the center.

With this configuration, greater radiation energy is emitted from both ends of the heating tube than from the center, so when maintaining the temperature of the heated object after heating, it is possible to suppress temperature unevenness of the heated object in the longitudinal direction of the heating tube.

The heating device according to the second aspect of the present disclosure is the heating device according to the first aspect of the present disclosure, and further includes a moving device that changes the distance between the support member and the heater, and a control device that controls the moving device so that the distance between the support member and the heater is set to a first predetermined distance when the temperature of the object to be heated is increased, and is set to a second predetermined distance that is shorter than the first predetermined distance when the object to be heated is maintained at the heated temperature.

If a heating tube is used that emits greater radiant energy from both ends than from the center, with an emphasis on maintaining the temperature of the object to be heated after heating, the ends are more likely to become hotter than the center during the heating process of the object to be heated, which can lead to temperature unevenness. However, with the above configuration, radiant energy is irradiated over a wide area of the object to be heated or the support member when the object to be heated is heated, making it possible to suppress temperature unevenness in the object to be heated. When maintaining the temperature of the heated object to be heated, large radiant energy is irradiated to the outer edge parts, where temperature drops are likely to occur, making it possible to suppress temperature unevenness in the object to be heated.

The heating device according to the third aspect of the present disclosure is the heating device according to the first or second aspect of the present disclosure, in which the heater has a plurality of the heating tubes, and the heating tubes are arranged in a direction intersecting the axis of the heating tubes.

This configuration allows the object to be heated over a wide area while preventing uneven temperatures.

A method for manufacturing a solder-jointed object according to a fourth aspect of the present disclosure is a method for manufacturing an object solder-jointed using a heating device according to any one of the first to third aspects of the present disclosure, comprising the steps of: supplying the heating object having solder to the support member; setting the distance between the support member and the heater to the first predetermined distance and raising the heating object to a first predetermined temperature by the heater, the first predetermined temperature being lower than the melting point of the solder and being capable of reducing oxides present in the heating object; and The method includes the steps of: after the object to be heated has risen to the first predetermined temperature, setting the distance between the support member and the heater to the second predetermined distance and maintaining the object to be heated at the first predetermined temperature by the heater; supplying a reducing gas to the object to be heated that is maintained at the first predetermined temperature; and, after the reducing gas has been supplied to the object to be heated, setting the distance between the support member and the heater to the first predetermined distance and using the heater to raise the temperature of the object to a second predetermined temperature that is equal to or higher than the melting point of the solder, thereby performing solder bonding.

With this configuration, the object to be heated is heated evenly, and a soldered object with good solder joints can be produced.

According to the present disclosure, when maintaining the temperature of the heated object after heating, it is possible to suppress temperature unevenness of the heated object in the longitudinal direction of the heating tube.

1A is a schematic vertical cross-sectional front view of a reflow apparatus according to an embodiment, and FIG. 1B is a schematic plan view of the reflow apparatus according to an embodiment. FIG. 2A is a schematic vertical cross-sectional front view of the reflow apparatus when the plate is in a first heating position, and FIG. 2B is a schematic vertical cross-sectional front view of the reflow apparatus when the plate is in a second heating position. 4 is a flowchart showing a procedure for manufacturing a solder-bonded substrate according to one embodiment. FIG. 2A is a side view of the heater and its surroundings when the plate is in the first heating position, and FIG. 2B is a side view of the heater and its surroundings when the plate is in the second heating position.

The following describes the embodiments with reference to the drawings. Note that in each drawing, identical or similar reference numerals are used for identical or corresponding components, and duplicate explanations are omitted.

First, referring to FIG. 1(A), a reflow apparatus 1 according to one embodiment will be described. FIG. 1(A) is a schematic front vertical cross-sectional view of the reflow apparatus 1. The reflow apparatus 1 is an apparatus that mainly performs solder bonding. The solder bonding referred to here includes forming solder bumps on a substrate and mounting electronic components on a substrate having solder bumps. When forming solder bumps on a substrate, a substrate having raw solder arranged on its surface is heated inside the reflow apparatus 1. The raw solder melts once, and when the molten solder cools and solidifies, it typically becomes a hemispherical solder bump. On the other hand, when mounting electronic components on a substrate, a substrate having electronic components arranged on the solder bumps is heated inside the reflow apparatus 1. The solder bumps melt once, and the molten solder cools and solidifies, thereby soldering the electronic components to the substrate. In this way, the reflow apparatus 1 heats a substrate having solder, so that the reflow apparatus 1 can be said to be one form of a heating apparatus. First, the configuration of the reflow apparatus 1 will be described below. The reflow device 1 includes a chamber 10, a heater 20, a moving device 30, and a control device 60.

The chamber 10 forms a processing space 11 in which the substrate W is processed. The substrate W is an example of an object to be soldered, and corresponds to a heating object since it is an object to be processed including heating. The substrate W corresponds to what is generally called a workpiece (sometimes abbreviated simply as "work"). The chamber 10 has a floor 12, a wall 13, and a lid 14. The chamber 10 also has a plate 18 provided therein. In other words, the reflow device 1 also has the plate 18. The plate 18 can support the substrate W placed on its upper surface, and corresponds to a support member. In this embodiment, the plate 18 is formed in a rectangular flat plate shape. The surface of the plate 18 is formed to a size that can include one or more substrates W to be processed at once. The plate 18 is preferably formed of graphite from the viewpoint of quickly responding to temperature changes when heated or cooled, but may be formed of metal such as copper, stainless steel, or steel plate. Also, from the perspective of quickly responding to temperature changes when heated or cooled, it is preferable that the plate 18 be formed as thin (with a small volume) as possible while still maintaining its strength, in order to reduce its heat capacity.

In this embodiment, the floor body 12 is generally formed in a rectangular thick plate shape large enough to contain the plate 18. The floor body 12 is typically arranged so that the thick plate-shaped upper surface is horizontal. In this embodiment, the floor body 12 is located below the plate 18. In other words, the plate 18 is arranged above the floor body 12. The wall body 13 is connected to the floor body 12 so as to surround the four sides of the floor body 12. The wall body 13 protrudes upward from the floor body 12. The height at which the wall body 13 protrudes from the floor body 12 is a height at which the upper end surface of the wall body 13 is higher than the upper end of the substrate W placed on the plate 18 when the plate 18 is at the highest position during processing of the substrate W. The upper end surface of the wall body 13 is located at the same height throughout the entire periphery of the floor body 12. The wall body 13 may be integrally formed with the floor body 12, or may be attached to a separate floor body 12. In either case, no gap is formed between the floor 12 and the wall 13. The floor 12 and the wall 13 cooperate to form a rectangular parallelepiped structure, which has an opening at the top and has a processing space 11 formed therein. The lid 14 closes the opening at the top of the rectangular parallelepiped structure formed by the floor 12 and the wall 13. The lid 14 is typically formed in a plate shape of the same size as the floor 12. The lid 14 is placed on the entire upper end surface of the wall 13. This allows the processing space 11 surrounded by the floor 12, the wall 13, and the lid 14 to be sealed. The lid 14 is configured to be detachable from the wall 13. The lid 14 is typically automatically attached to and detached from the wall 13 by an opening/closing device (not shown), but may be manually attached by an operator.

The heater 20 heats the plate 18 on which the substrate W is placed by radiation (radiation heating). The heater 20 has a heating tube 21. The heating tube 21 is capable of emitting radiation energy, and in this embodiment, an infrared lamp heater is used. That is, in this embodiment, radiation energy is transmitted by infrared rays (typically far infrared rays). The heating tube 21 has an appearance of a long, thin rod, and in this embodiment, has an appearance of a round bar.

Here, the configuration of the heater 20 will be described in more detail with reference to FIG. 1(B). FIG. 1(B) is a schematic plan view illustrating the internal configuration of the chamber 10, with the plate 18 partially cut away to illustrate the structure of the heating tube 21. The heating tube 21 has approximately the same length as one side of the rectangle of the plate 18. The approximately same length here is intended to include not only the same length as the side of the plate 18, but also shorter and longer than the side of the plate 18 in the direction of the side of the plate 18, within a range in which the entire plate 18 can be heated. In this embodiment, the heater 20 has a plurality of heating tubes 21 arranged at a predetermined interval in a direction perpendicular to the longitudinal direction (direction in which the axis extends) of the heating tube 21 and in a horizontal direction. The predetermined interval can be appropriately adjusted within a range in which the entire plate 18 can be heated. In this embodiment, all of the heating tubes 21 are arranged parallel to one pair of opposing sides of the rectangular plate 18 (perpendicular to the other pair of opposing sides), but they may be arranged to extend at an angle to the sides of the plate 18. The heating tubes 21 do not have to be arranged parallel to each other, but from the viewpoint of suppressing the occurrence of temperature unevenness, it is preferable that they are arranged parallel to each other. Hereinafter, the direction in which the heating tubes 21 are arranged and which intersects with the longitudinal direction of the heating tubes 21 will be referred to as the "arrangement direction."

1B, the heating tube 21 has a higher winding density of the filament 22 that emits infrared rays at both ends than at the center in the longitudinal direction. In other words, in this embodiment, the heating tube 21 is a sparsely wound infrared lamp heater with a sparsely wound central portion in the longitudinal direction and a densely wound central portion at both ends. For this reason, the heating tube 21 is designed to emit greater radiant energy at both ends than at the center in the longitudinal direction. The reason why such a heating tube 21 is adopted is that when continuing to radiate infrared rays to maintain the heated temperature after the plate 18 is heated, if the infrared rays are radiated evenly in the longitudinal direction, the temperature of the plate 18 will decrease toward the end in the longitudinal direction. When the heating tube 21 of this embodiment is used, the temperature decrease at the end side of the plate 18 can be suppressed during heating to maintain the temperature. The change in the winding density of the filament 22 of the heating tube 21 may be increased at the same rate as moving from the central portion to the end. Alternatively, the longitudinal direction may be divided into a plurality of sections, with the same winding density within each section, and the sections with higher winding density toward the end may be arranged. In any case, it is advisable to determine the winding density of the filament 22 so that heating can be performed in such a way that the temperature unevenness of the plate 18 when maintaining the temperature is within an acceptable range.

As shown in FIG. 1A, each heating tube 21 is disposed on the floor 12. Therefore, each heating tube 21 is arranged below the plate 18. In this embodiment, a groove that fits the heating tube 21 is formed in the floor 12 in the portion where the heating tube 21 is disposed, and the heating tube 21 is fitted into the groove. The depth of the groove formed in the floor 12 can be, for example, 1/2 to the same as the diameter of the heating tube 21, and may be about 2/3 to 3/4 of the diameter of the heating tube 21. By embedding the lower part of the heating tube 21 in the floor 12, infrared rays radiated downward from the heating tube 21 are reflected by the floor 12 and radiated upward, so that more infrared rays can be radiated upward (toward the plate 18). In addition, a cooling block (not shown) may be provided between each heating tube 21. The cooling block (not shown) can be cooled by a cooling medium (not shown), and may be configured to protrude upward from the upper end of the heating tube 21. The plate 18 can be forced to cool by contacting it with such a cooling block (not shown).

In this embodiment, the moving device 30 changes the distance between the plate 18 and the heater 20 by moving the plate 18 up and down. The moving device 30 has a support pin 31, a connecting arm 32, a shaft 33, and a drive source 34. The support pin 31 is a member that supports the lower surface of the plate 18. The support pin 31 is formed in a long and thin rod shape. The support pin 31 is arranged to extend vertically and supports the plate 18 at its upper end. The support pin 31 is typically fixed to the lower surface of the plate 18, but may be supported in a manner that simply contacts the lower surface of the plate 18. In this embodiment, four support pins 31 are provided to support each of the four corners of the rectangular plate 18. However, six or eight support pins 31 may be provided to support a pair of sides or the middle of each side of the rectangular plate 18, or three or other numbers may be provided depending on the size and shape of the plate 18. Each support pin 31 is arranged to penetrate the floor body 12. In other words, the floor body 12 has a through hole through which the support pin 31 passes. A sealing measure (not shown) is applied around the support pin 31 that passes through the through hole of the floor body 12, so that the processing space 11 can be kept sealed even if the support pin 31 moves in the axial direction (up and down).

The connecting arm 32 is a member for moving each support pin 31 in a synchronized manner. The connecting arm 32 is formed in a thin plate shape or a frame shape, and the lower ends of all the support pins 31 are fixed to the connecting arm 32. The shaft 33 is formed in a rod shape and is arranged so that its axis extends vertically. The shaft 33 is arranged in a position corresponding to the centroid of the plate 18 when viewed in a plan view. The upper part of the shaft 33 is fixed to the connecting arm 32. The lower part of the shaft 33 is connected to the driving source 34. In this embodiment, the driving source 34 moves the shaft 33 up and down. By moving the shaft 33 up and down by the driving source 34, the connecting arm 32 and each support pin 31 connected to the shaft 33 also move up and down. As the driving source 34, an electric actuator is typically used, but an actuator using fluid pressure (hydraulic pressure, pneumatic pressure, etc.) may also be used.

Figures 2(A) and 2(B) show the change in the position of the plate 18 when the moving device 30 is operated. Figures 2(A) and 2(B) are schematic front vertical cross-sectional views of the reflow device 1 mainly showing the area around the plate 18. Figure 2(A) shows a state in which the plate 18 has been raised to make the distance between the plate 18 and the heater 20 relatively long. Figure 2(B) shows a state in which the plate 18 has been lowered to make the distance between the plate 18 and the heater 20 relatively short.

In addition to the above-mentioned configuration, the reflow apparatus 1 according to the present embodiment is equipped with a gas supply unit 40. The gas supply unit 40 supplies nitrogen gas N as an inert gas used in processing the substrate W and formic acid gas F as a reducing gas to the processing space 11. The gas supply unit 40 has a supply pipe 41, a nitrogen pipe 43, and a formic acid pipe 45. One end of the supply pipe 41 penetrates the wall body 13 and opens to the processing space 11. One end of the nitrogen pipe 43 and one end of the formic acid pipe 45 are connected to the other end of the supply pipe 41. The other end of the nitrogen pipe 43 is connected to a nitrogen source (not shown) that is a source of supply of nitrogen gas N. The nitrogen pipe 43 is provided with a nitrogen valve 44 that opens and closes the flow path. The other end of the formic acid pipe 45 is connected to a formic acid source (not shown) that is a source of supply of formic acid gas F. The formic acid pipe 45 is provided with a formic acid valve 46 that opens and closes the flow path. When the nitrogen valve 44 and the formic acid valve 46 are closed, the gas supply unit 40 does not supply gas to the processing space 11. The gas supply unit 40 is configured to supply nitrogen gas N to the processing space 11 by opening the nitrogen valve 44 with the formic acid valve 46 closed, and supply formic acid gas F to the processing space 11 by opening the formic acid valve 46 with the nitrogen pipe 43 closed. In this embodiment, nitrogen gas N or formic acid gas F is selectively supplied to the processing space 11 through the supply pipe 41, but the nitrogen gas N and formic acid gas F may be configured to be supplied to the processing space 11 through separate systems. In other words, the supply pipe 41 may be omitted, and one end of the nitrogen pipe 43 and one end of the formic acid pipe 45 may each be individually opened to the processing space 11.

The reflow apparatus 1 according to the present embodiment also includes an exhaust unit 50. The exhaust unit 50 exhausts the gas in the processing space 11 to the outside of the chamber 10. The exhaust unit 50 includes an exhaust pipe 51, a vacuum pump 52, and an exhaust valve 53. The exhaust pipe 51 is a pipe that forms a flow path that guides the gas in the processing space 11 to the outside of the system. One end of the exhaust pipe 51 penetrates the wall body 13 and opens to the processing space 11. The other end of the exhaust pipe 51 is connected to an exhaust processing device (not shown). The exhaust processing device (not shown) processes the gas exhausted from the processing space 11 to such an extent that it can be released to the atmosphere. The vacuum pump 52 is configured to exhaust the gas in the processing space 11 to create a negative pressure in the processing space 11. The vacuum pump 52 is provided in the exhaust pipe 51. The exhaust valve 53 is a member that can block the flow path of the exhaust pipe 51, and is configured to allow the flow of gas when open and block the flow of gas when closed. In this embodiment, the exhaust valve 53 is provided in the exhaust pipe 51 between the chamber 10 and the vacuum pump 52. Typically, the exhaust unit 50 keeps the vacuum pump 52 running at all times while the reflow apparatus 1 is in operation, and switches between exhausting and not exhausting the processing space 11 by opening and closing the exhaust valve 53, but the vacuum pump 52 may be started and stopped in conjunction with the opening and closing of the exhaust valve 53.

The control device 60 is a device that controls the operation of the reflow device 1. The control device 60 is connected to an opening/closing device (not shown) that opens and closes the lid 14 of the chamber 10 via a control signal line, and is configured to be able to open and close the lid 14 by operating the opening/closing device (not shown). The control device 60 is also connected to the heater 20 via a control signal line, and is configured to be able to individually adjust the output of each heating tube 21. The control device 60 is also connected to the drive source 34 of the moving device 30 via a control signal line, and is configured to be able to control the direction and amount of movement of the support pin 31 (and thus the plate 18) by operating the drive source 34. The control device 60 is also connected to each of the nitrogen valve 44 and the formic acid valve 46 of the gas supply unit 40 via control signal lines, and is configured to be able to individually control the opening and closing of the nitrogen valve 44 and the formic acid valve 46. The control device 60 is also connected to the vacuum pump 52 of the exhaust unit 50 via a control signal line, and is configured to be able to control the start and stop of the vacuum pump 52. The control device 60 is connected to the exhaust valve 53 via a control signal line, and is configured to be able to individually control the opening and closing of the exhaust valve 53. The control device 60 also has a timer, and is configured to be able to measure any time. The control signal line described above indicates the concept of a function that can exchange control signals, and may be either wired or wireless.

Next, referring to FIG. 3, a method for manufacturing a solder-bonded substrate will be described. A solder-bonded substrate is a substrate W on which soldering has been performed, and corresponds to a solder-bonded object. FIG. 3 is a flow chart showing the steps for manufacturing a solder-bonded substrate. The method for manufacturing a solder-bonded substrate described below is carried out using the reflow apparatus 1 described thus far. The following description of the method for manufacturing a solder-bonded substrate using the reflow apparatus 1 also includes a description of the operation of the reflow apparatus 1. In the following description, when referring to the configuration of the reflow apparatus 1, reference will be made to FIG. 1(A) and FIG. 1(B) as appropriate.

When the reflow device 1 is stopped, the nitrogen valve 44 and the formic acid valve 46 are closed, the vacuum pump 52 is stopped, and the exhaust valve 53 is closed. When the production of the solder-bonded substrate is started, the substrate W having the solder is placed on the plate 18 (S1). The placement of the substrate W on the plate 18 is one form of supplying the substrate W to the plate 18. When placing the substrate W on the plate 18, it is preferable to place the substrate W so that the centroid of the substrate W coincides with the centroid of the plate 18. The coincidence of the centroids here does not require strict coincidence, but it is sufficient that the centroids coincide to the extent that the temperature unevenness when the substrate W is heated in a later process is within an acceptable range. After the substrate W is placed on the plate 18, the lid 14 of the chamber 10 is closed. By closing the lid 14, the processing space 11 in the chamber 10 is sealed.

The control device 60 then starts the vacuum pump 52 and alternately opens and closes the exhaust valve 53 and the nitrogen valve 44 to replace the gas in the processing space 11 with nitrogen gas N (S2). In this embodiment, the exhaust valve 53 opens first, and when the pressure in the processing space 11 is reduced to about 100 Pa (absolute pressure), the exhaust valve 53 closes. After that, the nitrogen valve 44 opens, and when nitrogen gas N flows into the processing space 11, the nitrogen valve 44 closes. This is repeated once or several times to replace the gas in the processing space 11 with nitrogen gas N.

Next, the control device 60 operates the moving device 30, which raises the plate 18, thereby setting the plate 18 to the first heating position (S3). Here, the first heating position is a position when the temperature of the substrate W placed on the plate 18 is raised, and is a position where the distance between the plate 18 and the heater 20 is relatively long (see FIG. 2(A)). The distance between the plate 18 and the heater 20 when the plate 18 is in the first heating position corresponds to the first predetermined distance. When infrared rays are radiated at a certain solid angle from an arbitrary point of the heating tube 21, the area of the infrared rays that hit the plate 18 becomes larger as the distance between the heating tube 21 and the plate 18 becomes longer. Since the heating tube 21 of the reflow device 1 according to this embodiment has a higher winding density of the filament 22 at both ends than at the center in the longitudinal direction, if the plate 18 and the heater 20 are brought close to each other to raise the temperature of the substrate W, temperature unevenness may occur in which the temperature at the edge of the substrate W becomes higher. This is because when the temperature is increased, a large amount of radiation energy is radiated from the heating tube 21 in a relatively short time, and if the plate 18 and the heater 20 are close to each other, the difference in radiation energy appears as a temperature difference. Therefore, in the reflow device 1 according to the present embodiment, the distance between the plate 18 and the heater 20 is relatively long during heating, so that the area on which the infrared rays radiated from any point of the heating tube 21 hit the plate 18 is relatively large. Therefore, when the plate 18 is in the first heating position, the sparse and dense effect of the heating tube 21, which is a sparsely and densely wound infrared lamp heater, is weakened (see FIG. 4(A)), and the temperature of the end of the plate 18 is prevented from rising excessively. In other words, the intensity difference of the infrared rays radiated from the heating tube 21 is mitigated when they hit the plate 18, and it is possible to prevent temperature unevenness from occurring in the plate 18 and the substrate W. From this perspective, the first predetermined distance may be set so that the temperature unevenness of the plate 18 (and thus the substrate W) during heating is within an acceptable range.

After the plate 18 is set to the first heating position, the control device 60 activates the heater 20 to start heating the substrate W (S4). The heating here aims to heat the substrate W to a reduction temperature. The reduction temperature is a temperature that is lower than the melting point of the solder in the substrate W and is suitable for reducing oxides present in the substrate W having solder in the presence of a reducing gas, and corresponds to the first predetermined temperature. In this embodiment, since formic acid gas F is used as the reducing gas, the reduction temperature is, for example, 180°C to 220°C (typically about 200°C), and may have a range. In this process of raising the temperature of the substrate W to the reduction temperature, the outputs of the multiple heating tubes 21 are typically made the same. This is because the heating tubes 21 emit relatively large radiant energy during the temperature rise, so there is little risk of partial temperature drops and large temperature unevenness. In this embodiment, the time required for the substrate W to reach the reduction temperature under the heating conditions is determined in advance, and the substrate W is heated under those conditions for the predetermined time, thereby raising the substrate W to the reduction temperature.

When the temperature of the substrate W rises to the reduction temperature, the control device 60 operates the moving device 30, which lowers the plate 18 to set the plate 18 to the second heating position (S5). Here, the second heating position is a position where the substrate W whose temperature has risen is maintained at that temperature, and is a position where the distance between the plate 18 and the heater 20 is relatively short (see FIG. 2(B)). The distance between the plate 18 and the heater 20 when the plate 18 is in the second heating position corresponds to the second predetermined distance. When maintaining the substrate W whose temperature has risen at that temperature, in the case of a normal heating tube with a constant filament winding density, if the output of the heating tube is reduced from the output at the time of temperature rise, the temperature of the end of the plate tends to be lower than the temperature of the center. Therefore, in the reflow device 1 according to the present embodiment, the distance between the plate 18 and the heating tube 21 is shortened in order to supply greater radiant energy to the end of the plate 18 than to the center when maintaining the temperature. As a result, infrared rays emitted from both ends of the heating tube 21, where the filaments 22 are dense, do not spread to the center, but instead hit the edge of the plate 18 directly above (see Figure 4 (B)), imparting greater thermal energy to the edge of the plate 18 than to the center.

Once the plate 18 is set to the second heating position, the control device 60 reduces the output of the heating tubes 21 to maintain the temperature of the substrate W at the reduction temperature (S6). The output of the heating tubes 21 is reduced in order to avoid the temperature of the substrate W rising above the reduction temperature if the output of the heating tubes 21 is continued during the temperature rise. If the output of the heating tubes 21 is reduced too much, the temperature of the substrate W will fall below the reduction temperature. Therefore, the output of the heating tubes 21 here is set to an output that can maintain the temperature of the substrate W at the reduction temperature. At this time, in this embodiment, the control device 60 adjusts the output of the heating tubes 21 arranged in the arrangement direction so that the output of the heating tubes 21 arranged at both ends is greater than that of the heating tube 21 arranged in the center. This is to avoid the fact that, as described above, if the output of the heating tubes 21 is reduced to maintain the temperature of the substrate W whose temperature has risen to a predetermined temperature (the reduction temperature in this embodiment), the temperature of the end of the plate 18 tends to fall below the temperature of the center. In this way, during the process of maintaining the temperature of the substrate W, a heating tube 21 is used in which the winding density of the filament 22 at both ends is higher than that at the center in the longitudinal direction of the heating tube 21, and the output of the heating tube 21 is increased toward both ends in the arrangement direction, thereby leveling out the temperature of the substrate W.

When the temperature of the substrate W rises to the reduction temperature, the control device 60 opens the exhaust valve 53 to exhaust the gas inside the processing space 11 (S7). At this time, it is preferable to exhaust substantially all of the gas inside the processing space 11 by reducing the pressure inside the processing space 11 to about 50 Pa to 100 Pa (absolute pressure). Here, exhausting substantially all of the gas inside the processing space 11 is intended to exhaust substances other than formic acid gas F so that the formic acid gas F inside the processing space 11 has a desired concentration when the formic acid gas F is flowed into the processing space 11 in a later process. In this embodiment, the time required to exhaust the gas inside the processing space 11 is obtained in advance, and when a predetermined time has elapsed since the exhaust valve 53 was opened, the control device 60 closes the exhaust valve 53. In the example shown in FIG. 3, the steps are performed in the order of a step (S5) of setting the plate 18 at the second heating position, a step (S6) of lowering the output of the heating tube 21 to maintain the temperature of the substrate W at the reducing temperature, and a step (S7) of exhausting the gas inside the processing space 11. However, the step (S5) of setting the plate 18 at the second heating position, the step (S6) of maintaining the temperature of the substrate W at the reducing temperature, and the step (S7) of exhausting the gas inside the processing space 11 may be performed simultaneously. Alternatively, the order in which these steps (S5, S6, S7) are started may be changed as appropriate.

While the temperature of the substrate W is maintained at the reduction temperature, the control device 60 opens the formic acid valve 46 to allow formic acid gas F to flow into the processing space 11 (S8). When the formic acid gas F flows into the processing space 11, the oxides are reduced in the substrate W heated to the reduction temperature. In this embodiment, the plate 18 and thus the substrate W are maintained at a generally uniform temperature, so that the oxide reduction is performed evenly and appropriately. In this embodiment, the time required for the oxide reduction to be completed under the conditions for the oxide reduction (temperature of the substrate W, formic acid gas F concentration in the processing space 11, etc.) is previously calculated, and the control device 60 determines the completion of the reduction when the previously calculated time has elapsed.

When the reduction of the oxides on the substrate W is complete, the control device 60 alternately opens and closes the exhaust valve 53 and the nitrogen valve 44 to replace the gas in the processing space 11 with nitrogen gas N (S9). The procedure for replacing with nitrogen gas N here is the same as in the step of replacing with nitrogen gas N described above (S2). When the replacement with nitrogen gas N is complete, the control device 60 operates the moving device 30, which raises the plate 18, thereby setting the plate 18 to the first heating position (S10). The first heating position here is the position when the temperature of the substrate W placed on the plate 18 is raised, as in the step of setting the plate 18 to the first heating position described above (S3) (see FIG. 2(A)).

After the plate 18 is set to the first heating position, the control device 60 increases the output of the heater 20 and starts heating the substrate W (S11). The heating here aims to heat the substrate W to the melting temperature of the solder. The melting temperature is a temperature equal to or higher than the melting point of the solder in the substrate W, which is suitable for soldering and corresponds to the second predetermined temperature. In this embodiment, the melting temperature is, for example, 230°C to 270°C (typically about 250°C), and may have a range. In this process of heating the substrate W to the melting temperature, the outputs of the multiple heating tubes 21 are typically set to the same. In this embodiment, the time required for the substrate W to reach the melting temperature under the conditions at the time of heating is calculated in advance, and the substrate W is heated under those conditions for the time calculated in advance, thereby raising the substrate W to the melting temperature. When the temperature of the substrate W rises to the melting temperature, the solder in the substrate W melts and soldering is performed.

Once the board W has been soldered, the control device 60 stops the heater 20 to stop heating the board W (S12). When the heater 20 stops, the temperature of the plate 18 and therefore the board W drops. When the temperature of the board W drops below the temperature at which the molten solder solidifies, the solder solidifies and a solder-jointed board is produced. Once the solder-jointed board has been produced, the lid 14 of the chamber 10 is opened at any time and the solder-jointed board is removed from the chamber 10 (S13). This completes the production of the solder-jointed board.

As described above, the reflow apparatus 1 according to this embodiment has the following effects. Since the winding density of the filament 22 of the heating tube 21 is higher at both ends than at the central portion in the longitudinal direction, the both ends can emit greater radiant energy than the central portion, and temperature unevenness of the substrate W can be suppressed when the substrate W is maintained at its temperature. In addition, the position of the plate 18 is set to the first heating position when the substrate W is heated, and to the second heating position closer to the heater 20 when the substrate W is maintained at the reducing temperature, so that the substrate W can be heated quickly while suppressing temperature unevenness when the substrate W is maintained at the reducing temperature.

In the above explanation, the reflow device 1 has been described as one embodiment of a heating device, but it goes without saying that the heating device according to the present disclosure can also be applied to devices other than reflow devices that require heating.

In the above explanation, the support member is a plate 18 that supports the entire underside of the substrate W, but it may also be a jig such as a frame that supports all or part of the edge of the substrate W. In this case, radiant heat from the heater 20 is directly irradiated onto the substrate W.

In the above description, the position of the heater 20 is fixed, and the plate 18 moves toward and away from the heater 20. However, the position of the plate 18 may be fixed, and the heater 20 may move relative to the plate 18, or the plate 18 and the heater 20 may move relative to each other.

In the above description, nitrogen gas N is used as the inert gas, but an inert gas other than nitrogen gas N, such as argon gas, may be used. In the above description, formic acid gas F is used as the reducing gas, but hydrogen gas or a carboxylic acid gas other than formic acid may be used as the reducing gas that reduces the oxides on the substrate W. In the above description, an inert gas (nitrogen gas N) is supplied before and after the reducing gas (formic acid gas F) is supplied to the processing space 11, but the supply of the inert gas may be omitted depending on the situation. In this case, it is not necessary to provide the nitrogen pipe 43 and the nitrogen valve 44.

In the above explanation, the process management during the manufacture of the solder-bonded substrate is performed based on the time measured by the control device 60. However, it is also possible to provide a thermometer that detects the temperature of the plate 18 and a pressure gauge that detects the pressure in the processing space 11, and to manage the process based on the values detected by these instruments.

In the above explanation, the heating device and the manufacturing method of the solder-joined object according to the embodiment of the present invention have been explained mainly using Figures 1(A) to 3 as examples, but the configuration, structure, number, arrangement, shape, material, etc. of each part are not limited to the above specific examples, and those that are appropriately selected and adopted by those skilled in the art are also included in the scope of the present invention as long as they include the gist of the present invention.

1 Reflow device 10 Chamber 11 Processing space 18 Plate (support member)
20 Heater 21 Heating tube 22 Filament 30 Moving device 40 Gas supply unit 50 Exhaust unit 60 Control device W Substrate (heating object)

Claims (3)

A support member for supporting an object to be heated;
A heater that radiates heat to the object to be heated that is supported by the support member, or the support member that supports the object to be heated, the heater having a heating tube that emits greater radiation energy at both end portions than at a center portion ;
a moving device for changing the distance between the support member and the heater;
and a control device that controls the moving device so as to set the distance between the support member and the heater to a first predetermined distance when the temperature of the object to be heated is increased, and to set the distance to a second predetermined distance shorter than the first predetermined distance when the object to be heated is maintained at the heated temperature.
Heating device. The heater has a plurality of the heating tubes, and the plurality of the heating tubes are arranged in a direction intersecting an axis of the heating tube.
The heating device according to claim 1 . A method for manufacturing an object soldered using the heating device according to claim 1 or 2 , comprising the steps of:
supplying the heating object having solder to the support member;
a step of setting a distance between the support member and the heater to the first predetermined distance and raising the temperature of the object to be heated to a first predetermined temperature by the heater, the first predetermined temperature being lower than a melting point of the solder and being a temperature capable of reducing oxides present in the object to be heated;
After the temperature of the object to be heated has risen to the first predetermined temperature, a distance between the support member and the heater is set to the second predetermined distance and the object to be heated is maintained at the first predetermined temperature by the heater;
supplying a reducing gas to the object to be heated that is maintained at the first predetermined temperature;
and after the reducing gas is supplied to the object to be heated, a distance between the support member and the heater is set to the first predetermined distance, and the object to be heated is heated to a second predetermined temperature equal to or higher than a melting point of the solder by the heater, thereby performing solder bonding.
A method for manufacturing a soldered object.