Heating device and method for manufacturing soldered objects

Abstract

The present invention provides a heating device and a method for manufacturing soldered objects that suppress the occurrence of temperature unevenness within an acceptable range during both the heating and temperature maintenance processes with a relatively simple configuration. [Solution] The heating device 1 comprises a support member 18 that supports an object to be heated, and a heater 20 that heats the object to be heated supported by the support member 18 or the support member 18 that supports the object to be heated. The heater 20 has a plurality of annular heating elements 20P, each heating element 20P having a different circumference and arranged in a nested manner, and is capable of outputting different amounts of heat from each other and the amount of heat output can be changed. The method for manufacturing a soldered object using the heating device 1 involves supplying the object to be heated to the support member 18, generating heat in the heating elements 20P to raise the temperature of the object to be heated to a first predetermined temperature, maintaining the first predetermined temperature by changing the output ratio of the heating elements 20P, supplying reducing gas, and increasing the output of the heating elements 20P to raise the temperature to a second predetermined temperature to perform soldering.

Description

[Technical Field]

[0001] The present disclosure relates to a heating apparatus and a method for manufacturing a solder-bonded object. [Background Art]

[0002] In a reflow apparatus that performs soldering on a substrate, there has been known an apparatus that suppresses the occurrence of temperature unevenness where the temperature at the edge of a plate becomes lower than that at the central portion when heating the plate to heat the substrate placed on the plate. The reflow apparatus radiatively heats the plate on which the substrate is placed by arranging in parallel a plurality of疏密-wound infrared lamp heaters in which the winding density of the filament is sparse at the central portion in the longitudinal direction and dense at both end portions (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2024-106687 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the process of raising the substrate temperature from a relatively low temperature to a predetermined temperature (for example, a temperature suitable for reducing oxides on the substrate), the proportion of heat dissipation from the outer part of the plate tends to be smaller than in the process of maintaining the predetermined temperature after heating. In other words, the heat dissipation ratio between the central and outer parts of the plate changes between the heating process and the temperature maintenance process. Since the winding density of the filament cannot be changed during use in a densely wound infrared lamp heater, the output ratio between the central and outer parts is predetermined. For this reason, in a reflow apparatus using a densely wound infrared lamp heater, it is difficult to suppress the occurrence of temperature unevenness within an acceptable range in both the heating process and the temperature maintenance process, where the heat dissipation characteristics of the plate differ. It is conceivable to install a heater that changes output between the heating process and the temperature maintenance process, separate from the densely wound infrared lamp heater, but this would lead to increased complexity and size of the apparatus.

[0005] In view of the above-mentioned problems, this disclosure relates to a heating device and a method for manufacturing a soldered object, which suppress the occurrence of temperature unevenness within an acceptable range in both the heating process and the temperature maintenance process with a relatively simple configuration. [Means for solving the problem]

[0006] A heating device according to a first aspect of the present disclosure comprises a support member for supporting an object to be heated, and a heater for heating the object to be heated supported by the support member, or the support member supporting the object to be heated, the heater having a plurality of annular heating elements, each of the plurality of heating elements having a different circumference and arranged in a nested manner, and being capable of outputting different amounts of heat from each other and being able to change the amount of heat output.

[0007] With this configuration, it is possible to change the output of the heating elements on the outside and inside separately according to the required amount of heat, using a relatively simple structure, thereby suppressing the occurrence of temperature unevenness.

[0008] Furthermore, as a heating device according to a second aspect of the present disclosure, in the heating device according to the first aspect of the present disclosure, the support member is a plate-shaped member on which the object to be heated is placed, and the heater may heat the plate-shaped member.

[0009] With this configuration, when heating multiple objects with different reflectivity in sequence, it is possible to suppress variations in the energy required to raise the temperature of each object to a predetermined level.

[0010] Furthermore, as a heating device according to a third aspect of the present disclosure, in the heating device according to the first or second aspect of the present disclosure, at least one of the heating elements may be divided in the circumferential direction.

[0011] This configuration allows for the subdivision of the temperature-controllable region, enabling finer temperature control.

[0012] Furthermore, as a heating device according to a fourth aspect of the present disclosure, a heating device according to any one of the first to third aspects of the present disclosure may be provided with a control device for controlling the output of each of the heating elements.

[0013] With this configuration, the output of each heating element can be adjusted according to the condition of the object being heated.

[0014] Furthermore, as a heating device according to a fifth aspect of the present disclosure, in the heating device according to the fourth aspect of the present disclosure, the control device may control the output of each heating element such that the output of the outer heating element is greater than or equal to the output of the inner heating element, and the output of the outermost heating element is greater than the output of the innermost heating element.

[0015] With this configuration, the output of the heating element can be increased on the outer side, where heat dissipation is relatively easier, and the temperature drop on the outside of the object being heated compared to the inside can be suppressed.

[0016] Furthermore, as a heating device according to a sixth aspect of the present disclosure, in a heating device according to a fourth or fifth aspect of the present disclosure, the control device may increase the ratio of the output of the outer heating element to the output of the inner heating element when it determines that the temperature of the object to be heated has reached a predetermined temperature.

[0017] This configuration makes it possible to suppress the occurrence of temperature unevenness, for example, when transitioning from the heating process to the heat retention process.

[0018] A method for manufacturing a soldered object according to a seventh aspect of the present disclosure is a method for manufacturing an object that has been soldered using a heating device according to a fifth aspect of the present disclosure, comprising the steps of: supplying the object to be heated, which has solder, to a support member; generating heat from a heating element to raise the temperature of the object to be heated to a first predetermined temperature, wherein the first predetermined temperature is below the melting point of the solder and is a temperature at which oxides present in the object to be heated can be reduced; after the temperature of the object to be heated has risen to the first predetermined temperature, increasing the ratio of the output of the outer heating element to the output of the inner heating element to maintain the temperature of the object to be heated at the first predetermined temperature; supplying a reducing gas to the object to be heated which is maintained at the first predetermined temperature; and after the reducing gas has been supplied to the object to be heated, increasing the output of the heating element to raise the object to a second predetermined temperature above the melting point of the solder to perform soldering.

[0019] With this configuration, the object to be heated is heated evenly, making it possible to manufacture soldered objects with good solder joints. [Effects of the Invention]

[0020] According to this disclosure, with a relatively simple configuration, the output of the heating element can be changed independently on the outside and inside according to the required amount of heat, thereby suppressing the occurrence of temperature unevenness. [Brief explanation of the drawing]

[0021] [Figure 1] It is a perspective view showing the schematic configuration of a reflow apparatus according to an embodiment of the present disclosure. [Figure 2] It is a schematic plan view of the reflow apparatus according to an embodiment of the present disclosure. [Figure 3] It is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] It is a flowchart showing the manufacturing procedure of a solder-bonded substrate according to an embodiment of the present disclosure. [Figure 5] (A) is a schematic plan view of a reflow apparatus according to a first modification of the embodiment of the present disclosure, and (B) is a schematic plan view of a reflow apparatus according to a second modification of the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding members are denoted by the same or similar reference numerals, and repeated description thereof will be omitted. In addition, the dimensions and ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

[0023] First, the reflow apparatus 1 according to the embodiment of this disclosure will be described with reference to Figures 1 to 3. Figure 1 is a perspective view showing the schematic configuration of the reflow apparatus 1. Figure 2 is a schematic plan view of the reflow apparatus 1. Figure 3 is a cross-sectional view taken along the line III-III in Figure 2. The reflow apparatus 1 is a device that primarily performs solder joining. Solder joining, as used herein, 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 with raw solder arranged on its surface is heated inside the reflow apparatus 1. The raw solder then melts, and when the molten solder cools and solidifies, it typically forms hemispherical solder bumps. On the other hand, when mounting electronic components on a substrate, the electronic components are placed on the solder bumps on the substrate where the solder bumps have been formed, and the substrate is heated inside the reflow apparatus 1. The solder bumps then melt, and as the molten solder cools and solidifies, the electronic components are soldered to the substrate. Thus, since the reflow apparatus 1 heats the substrate containing solder, it can be said that the reflow apparatus 1 is a form of heating device. Below, we will first explain the configuration of the reflow apparatus 1.

[0024] In this embodiment, the reflow apparatus 1 comprises a chamber 10, a plate 18, a heater 20, support pins 31, and a control device 60. Figure 1 shows the chamber 10 with the lid 14 open. Figure 2 shows the configuration and arrangement of the heater 20, with the arrangement of the lid 14 and plate 18 indicated by dashed lines. Figure 3 shows the chamber 10 with the lid 14 closed.

[0025] Chamber 10 forms a processing space 11 (see Figure 3) for processing a substrate W (see Figure 3). The substrate W is an example of an object to be soldered and is subject to processing that includes heating, and therefore corresponds to an object to be heated. The substrate W corresponds to what is generally called a workpiece (sometimes simply abbreviated as "work"), and in this embodiment, it is described as being formed in a circular, plate-like shape (hereinafter referred to as "disc-shaped"). In this embodiment, since a disc-shaped substrate W is handled, the plate 18 that supports the substrate W is also formed in a circular shape. Chamber 10 has a floor 12, a wall 13, and a lid 14.

[0026] The floor body 12 is a component that constitutes the floor of the processing space 11. The floor body 12 is made of a thick plate-like member formed to a size that encompasses the plate 18. In this embodiment, the floor body 12 is formed in a circular shape when viewed from above, but it may be formed in a rectangular or other polygonal shape. As shown in Figure 3, the floor body 12 has grooves 12G formed therein that house the heater 20. For this reason, the floor body 12 has a thickness that allows for the formation of grooves 12G. In this embodiment, cooling blocks 12C are provided between adjacent grooves 12G of the floor body 12. The cooling blocks 12C typically cool the plate 18 by at least one of heat transfer and thermal radiation. The cooling blocks 12C typically have cooling fluid channels (not shown) arranged on the surface and / or inside for the flow of a cooling fluid, and are cooled by heat exchange with the cooling fluid.

[0027] The wall 13 is a component that constitutes the wall of the processing space 11. The wall 13 is made of a thick plate-like material, and a hole 13H is formed inside it in a plan view. The hole 13H is large enough to accommodate the plate 18 and to be contained within the floor 12, and in this embodiment, it is formed in a circular shape. In other words, in this embodiment, the hole 13H is formed in a circular shape that is larger than the plate 18 and smaller than the floor 12. The floor 12 is connected to the bottom surface of the wall 13 in a way that closes the bottom of the hole 13H, thereby forming a processing space 11 with an open top inside the hole 13H. That is, the inner surface of the hole 13H becomes the wall surface of the processing space 11. Therefore, the required height for the wall surface of the processing space 11 should be the thickness of the thick plate-like material that constitutes the wall 13. In this embodiment, a rectangular plate-like material is used for the thick plate-like material that constitutes the wall 13, but plate-like material of other shapes such as polygons, circles, or ellipses may also be used.

[0028] The lid 14 is a plate-shaped member that covers the open top surface of the processing space 11, which is formed by the floor 12 and the wall 13 and has an open top. The lid 14 is sized to encompass the hole 13H, and in this embodiment, a plate-shaped member with a circular top view is used. The lid 14 can be attached to and detached from the wall 13, and when the lid 14 is attached to the wall 13, the processing space 11 is typically sealed. Attaching and detaching the lid 14 to the wall 13 is typically done automatically by an opening and closing device (not shown), but it may also be configured to be done manually by an operator.

[0029] The plate 18 is a component on which the substrate W is placed. The plate 18 can support the substrate W placed on its upper surface and is equivalent to a support member. In this embodiment, the plate 18 is a circular, flat member. Because the plate 18 is formed in a circular shape, its volume can be reduced compared to, for example, a rectangular shape large enough to encompass the substrate W, and thus its heat capacity can be reduced. In addition, the processing space 11 can be made cylindrical, and the volume inside the chamber 10 (i.e., the processing space 11) can be reduced. The surface on which the substrate W is placed (hereinafter referred to as the "substrate placement surface") of the plate 18 is formed to be large enough to encompass the entire substrate W. From the viewpoint of quickly responding to temperature changes when heated or cooled, the plate 18 is typically a carbon plate made of carbon. The carbon plate may be made of graphite. Alternatively, the plate 18 may be made of a metal such as copper, stainless steel, or steel plate. Furthermore, from the viewpoint of quickly responding to temperature changes when heated or cooled, the plate 18 is preferably formed as thin as possible (i.e., with a small volume) while maintaining strength, in order to reduce its heat capacity. In addition, the plate 18 is preferably flat on the substrate mounting surface so as to maximize the contact area with the substrate W.

[0030] The heater 20 is a device for heating the substrate W. In this embodiment, the heater 20 directly heats the plate 18 supporting the substrate W, and indirectly heats the substrate W through heat transfer from the heated plate 18. In this embodiment, the heater 20 has a plurality of heating tubes, as most clearly shown in Figure 2: a first heating tube 21, a second heating tube 22, a third heating tube 23, a fourth heating tube 24, and a fifth heating tube 25. When referring to the common configuration or characteristics of these plurality of heating tubes 21, 22, 23, 24, and 25, they will be collectively referred to as heating tubes 20P. The heating tubes 20P emit heat and correspond to heating elements. In this embodiment, the heating tubes 20P convert input power into heat, and typically an infrared lamp heater (sometimes called an IR heater) is used, but other heaters such as resistance heaters may be used. Also, in this embodiment, the heating tubes 20P are formed in an annular shape.

[0031] The first heating tube 21, the second heating tube 22, the third heating tube 23, the fourth heating tube 24, and the fifth heating tube 25 each have different annular diameters (and circumferences), and in this embodiment, they are arranged concentrically. The diameter of the first heating tube 21 is larger than the diameter of the second heating tube 22. The diameter of the second heating tube 22 is larger than the diameter of the third heating tube 23. The diameter of the third heating tube 23 is larger than the diameter of the fourth heating tube 24. The diameter of the fourth heating tube 24 is larger than the diameter of the fifth heating tube 25. With this configuration, the first heating tube 21, the second heating tube 22, the third heating tube 23, the fourth heating tube 24, and the fifth heating tube 25 are arranged in a nested manner inside the annular shape in the order listed above. Each heating tube 20P is placed in a groove 12G formed in the base body 12. In other words, the groove 12G is formed in a position that allows each heating tube 20P to be arranged in the nested manner described above. The depth of groove 12G is approximately the same as the diameter of heating tube 20P (i.e., the length of the cross-section perpendicular to the longitudinal direction of heating tube 20P).

[0032] The first heating tube 21, the second heating tube 22, the third heating tube 23, the fourth heating tube 24, and the fifth heating tube 25 can each have their output set independently, meaning they can output different amounts of heat from one another. In addition, the amount of heat output of each heating tube 20P can be changed. With this configuration, for example, the heating tubes 20P located on the outside can have a higher output, and the difference in output between the heating tubes 20P located on the inside and those located on the outside can be changed over time.

[0033] In this embodiment, the first heating tube 21, the second heating tube 22, and the third heating tube 23 are divided circumferentially. This suppresses the occurrence of temperature differences depending on the position of the heating tube 20P in the circumferential (or longitudinal) direction. In this embodiment, the first heating tube 21, which has a relatively long circumference, is divided into four equal parts circumferentially, while the second heating tube 22 and the third heating tube 23, which have shorter circumferences than the first heating tube 21, are divided into two equal parts circumferentially. The fourth heating tube 24 and the fifth heating tube 25 are not divided circumferentially, but rather have a broken end at one point in the circumferential direction, rather than being an infinitely continuous ring. Each heating tube 20P is bent toward the base body 12 at the circumferentially divided or broken end, passes through the base body 12, and is connected to a power supply (not shown) outside the chamber, typically via lead wires.

[0034] The support pins 31 are members that support the lower surface of the plate 18. The support pins 31 are formed in the shape of an elongated rod. The support pins 31 are arranged to extend vertically and support the plate 18 at their upper ends. The support pins 31 are typically fixed to the lower surface of the plate 18, but they may also be supported by simply contacting the lower surface of the plate 18. In this embodiment, a total of six support pins 31 are provided in three pairs of two, so as to support the outer circumference of the circular plate 18 at appropriate intervals. In each pair of support pins 31, the two support pins 31 are typically positioned so that a virtual line connecting them passes through the center of the circular plate 18. However, the number and arrangement of the support pins 31 can be appropriately changed, for example, depending on the size and shape of the plate 18. Each support pin 31 can reciprocate up and down by the operation of a drive source (not shown). The drive source (not shown) is typically an electric actuator, but an actuator utilizing fluid pressure (e.g., hydraulic or pneumatic) may also be used. Each support pin 31 is arranged to penetrate the floor body 12. In other words, the floor body 12 has through holes through which each support pin 31 passes. Each support pin 31 passing through the through holes in the floor body 12 is sealed (not shown), so that the sealing of the processing space 11 can be maintained even if each support pin 31 moves in the axial direction (i.e., up and down). As each support pin 31 moves up and down, the plate 18 can move up and down between a position in contact with the cooling block 12C and a position above the cooling block 12C.

[0035] In addition to the configuration described above, the reflow apparatus 1 according to this embodiment is equipped with a gas supply unit 40, as shown in Figure 3. The gas supply unit 40 supplies nitrogen gas N as an inert gas and formic acid gas F as a reducing gas to the processing space 11 for processing the substrate W. The gas supply unit 40 has a supply pipe 41, a nitrogen pipe 43, and a formic acid pipe 45. One end (or first end) of the supply pipe 41 penetrates the floor 12 and opens into the processing space 11. One end (or first end) of the nitrogen pipe 43 and one end (or first end) of the formic acid pipe 45 are connected to the other end (or second end) of the supply pipe 41. The other end (or second end) of the nitrogen pipe 43 is connected to a nitrogen source (not shown) which is the source 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 (or second end) of the formic acid pipe 45 is connected to a formic acid source (not shown) that supplies 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 supplies nitrogen gas N to the processing space 11 by opening the nitrogen valve 44 with the formic acid valve 46 closed, and supplies 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 via the supply pipe 41, but nitrogen gas N and formic acid gas F may be supplied to the processing space 11 by separate systems. In other words, the supply pipe 41 may be omitted, and one end (or first end) of the nitrogen pipe 43 and one end (or first end) of the formic acid pipe 45 may each open individually into the processing space 11.

[0036] Furthermore, the reflow apparatus 1 according to this embodiment is equipped with an exhaust unit 50, as shown in Figure 3. The exhaust unit 50 discharges the gas in the processing space 11 to the outside of the chamber 10. The exhaust unit 50 has 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 for guiding the gas in the processing space 11 to the outside of the system. As shown in the figure, the exhaust pipe 51 penetrates the floor body 12 or the wall body 13, and one end (or first end) opens to the processing space 11. The other end (or second end) of the exhaust pipe 51 is connected to an exhaust treatment device (not shown). The exhaust treatment device (not shown) processes the gas discharged from the processing space 11 to the extent that it can be released into the atmosphere. The vacuum pump 52 is a device that pumps the gas in the processing space 11 to the outside, and by discharging the gas from the processing space 11, it creates negative pressure in the processing space 11. The vacuum pump 52 is located in the exhaust pipe 51. The exhaust valve 53 is a component capable of blocking the flow path of the exhaust pipe 51, allowing gas flow when open and blocking gas flow when closed. In this embodiment, the exhaust valve 53 is located 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 while the reflow apparatus 1 is operating, and switches between exhausting the processing space 11 by opening and closing the exhaust valve 53. However, the vacuum pump 52 may also be started and stopped in conjunction with the opening and closing of the exhaust valve 53.

[0037] The control device 60 is a device that controls the operation of the reflow apparatus 1. The control device 60 is connected by a communication line (wired or wireless; the same applies hereinafter) to an opening / closing device (not shown) that opens and closes the lid 14 of the chamber 10, and opens and closes the lid 14 by operating the opening / closing device (not shown). The control device 60 is also connected by a communication line to the heater 20 and individually controls the output of each heating tube 20P. The control device 60 is also connected by a control communication line to a drive source (not shown) that operates the support pins 31, and controls the direction and amount of movement of the support pins 31 (and thus the plate 18) by operating the drive source (not shown). The control device 60 is also connected by individual communication lines to the nitrogen valve 44 and the formic acid valve 46 of the gas supply unit 40, and individually controls the opening and closing of the nitrogen valve 44 and the formic acid valve 46. The control device 60 is also connected by a communication line to the vacuum pump 52 of the exhaust unit 50 and controls the starting and stopping of the vacuum pump 52. Furthermore, the control device 60 is connected to the exhaust valve 53 by a communication line and individually controls the opening and closing of the exhaust valve 53. The control device 60 also has a timer that measures any desired time.

[0038] The control device 60 may include at least one physical configuration, as shown in Figure 3, a processor 61, memory 62 (e.g., RAM and / or ROM), and storage 63. The control device 60 may also have, for example, a program in the memory 62 and / or storage 63 for properly operating the aforementioned devices, and the processor 61 may be used to execute this program. This program may include a sequence program that specifies the sequence and timing of operation for each of the aforementioned devices. The control device 60 is typically mounted on the outside of the chamber 10, but it may also be installed at a location away from the chamber 10 to remotely operate the reflow apparatus 1.

[0039] Next, the manufacturing method for solder-bonded substrates will be explained with reference to Figure 4. A solder-bonded substrate is a substrate W that has been solder-bonded, and corresponds to the object to be solder-bonded. Figure 4 is a flowchart showing the procedure for manufacturing a solder-bonded substrate. The manufacturing method for solder-bonded substrates described below is performed using the reflow apparatus 1 described above. The following explanation of the manufacturing method for solder-bonded substrates using the reflow apparatus 1 also serves as an explanation of the operation of the reflow apparatus 1. When the configuration of the reflow apparatus 1 is referred to in the following explanation, please refer to Figures 1 to 3 as appropriate. The operation of each device connected to the control device 60 by a communication line, as shown below, is typically controlled by the control device 60 unless otherwise specified.

[0040] While the reflow apparatus 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 manufacturing of solder-bonded substrates is started, first, a substrate W with solder is placed on the plate 18 (S1). Placing 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 it so that the centroid of the substrate W coincides with the centroid of the plate 18. The centroidal coincidence here does not require a strict coincidence, but it is sufficient if it coincides to the extent that the temperature unevenness when the substrate W is heated in a later process is within an acceptable range. Once the substrate W is placed on the plate 18, the lid 14 of the chamber 10 is closed. When the lid 14 is closed, the processing space 11 inside the chamber 10 becomes airtight.

[0041] Next, the control device 60 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 one to several times to replace the gas inside the processing space 11 with nitrogen gas N.

[0042] Next, the control device 60 activates each support pin 31, causing the plate 18 to rise and set the plate 18 to the heating position (S3). Here, the heating position is the position in which the temperature of the substrate W placed on the plate 18 is higher than the ambient temperature of the reflow apparatus 1, and the position in which the plate 18 is away from the cooling block 12C. By keeping the plate 18 away from the cooling block 12C, it is possible to prevent it from being cooled by heat transfer from the cooling block 12C during heating.

[0043] Once the plate 18 is set in the heating position, the control device 60 activates the heater 20 to start heating the substrate W (S4). The goal of this heating is to heat the substrate W to the reduction temperature. The reduction temperature is below the melting point of the solder present on the substrate W and is suitable for reducing oxides present on the solder-containing substrate W in the presence of a reducing gas, and corresponds to a 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 around 200°C), and may have a range. In this step of raising the temperature of the substrate W to the reduction temperature, the control device 60 controls the output of each heating tube 20P, which is arranged in a nested manner, so that the output of the outermost heating tube 20P is greater than or equal to the output of the innermost heating tube 20P, and the output of the outermost heating tube 20P (i.e., the first heating tube 21) is greater than the output of the innermost heating tube 20P (i.e., the fifth heating tube 25). This measure is based on the finding that when the entire plate 18 and thus the substrate W are heated uniformly, the outer surface tends to dissipate heat more easily and therefore has a lower temperature than the inner surface. It is a measure to suppress temperature unevenness in the plate 18 and thus the substrate W during heating. The difference or ratio of output between each heating tube 20P should be set considering the characteristics of the reflow apparatus 1 and the substrate W so as to minimize temperature unevenness in the heated substrate W. In this embodiment, whether or not the substrate W has risen to the reduction temperature during this heating process is estimated by first determining the time required for the substrate W to reach the reduction temperature under the heating conditions, and then heating the substrate W under those conditions for the predetermined time.

[0044] When the temperature of the substrate W rises to the reduction temperature, the control device 60 adjusts the output of each heating tube 20P to maintain the temperature of the substrate W at the reduction temperature (S5). In this temperature maintenance process, the goal is to maintain the substrate W at the reduction temperature, that is, to prevent the temperature of the substrate W from decreasing. Therefore, the output of the heater 20 is typically smaller than the output in the heating process (S4). In the process of maintaining the temperature of the substrate W at the reduction temperature (S5), the control device 60 controls the output of each heating tube 20P so that the output of the outer heating tube 20P is greater than or equal to the output of the inner heating tube 20P, while also increasing the ratio of the output of the outer heating tube 20P to the output of the inner heating tube 20P compared to the heating process (S4). This is based on the finding that the proportion of heat dissipation from the outside is greater in the temperature maintenance process (S5) than in the heating process (S4), and is a measure to suppress temperature unevenness in the plate 18 and, consequently, the substrate W, while it is being maintained at the reduction temperature. The difference or ratio of output between each heating tube 20P should be set considering the characteristics of the reflow apparatus 1 and the substrate W, so as to minimize temperature unevenness in the substrate W while maintaining the reduction temperature.

[0045] Furthermore, once the temperature of the substrate W rises to the reduction temperature, the control device 60 opens the exhaust valve 53 to discharge the gas inside the processing space 11 (S6). At this time, it is preferable to discharge 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, substantially discharging all of the gas inside the processing space 11 means discharging substances other than formic acid gas F so that when formic acid gas F is introduced into the processing space 11 in a later step, the formic acid gas F inside the processing space 11 will be at the desired concentration. In this embodiment, the time required to discharge the gas inside the processing space 11 is determined in advance, and once the predetermined time has elapsed since opening the exhaust valve 53, the control device 60 closes the exhaust valve 53. In the example shown in Figure 4, the steps are performed in the order of adjusting the output of each heating tube 20P to maintain the temperature of the substrate W at the reduction temperature (S5), and then discharging the gas inside the processing space 11 (S6). However, the steps of maintaining the temperature of the substrate W at the reduction temperature (S5) and discharging the gas inside the processing space 11 (S6) may be performed simultaneously. Alternatively, the order in which these steps (S5, S6) are started may be changed as appropriate.

[0046] 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 (S7). When formic acid gas F flows into the processing space 11, oxide reduction occurs in the substrate W, which has been heated to the reduction temperature. In this embodiment, since the plate 18 and thus the substrate W are maintained at a generally uniform temperature, the oxide reduction is carried out evenly and appropriately. In this embodiment, the time required for the oxide reduction to be completed under the conditions for oxide reduction (temperature of the substrate W, concentration of formic acid gas F in the processing space 11, etc.) is determined in advance, and the control device 60 determines the completion of the reduction after the predetermined time has elapsed.

[0047] Once the reduction of the oxides in 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 (S8). The procedure for replacement with nitrogen gas N here is the same as in the nitrogen gas replacement step (S2) described above.

[0048] Once the replacement with nitrogen gas N is complete, the control device 60 increases the output of the heater 20 and starts heating the substrate W (S9). The goal of heating the substrate W here is to heat it to the melting point of the solder. The melting point is a temperature above the melting point of the solder present in the substrate W, a temperature 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 around 250°C), and may have a range. In this step of raising the temperature of the substrate W to the melting point, the control device 60 typically sets the output of each heating tube 20P to the same setting as the output in the step of raising the temperature of the substrate W to the reduction temperature (S4). This is because the heating step involves less heat dissipation to the outside than the temperature maintenance step. In addition, considering that the melting temperature is higher than the reduction temperature, the output ratio between each heating tube 20P may be maintained in the same way as in the heating step to the reduction temperature (S4), while the output of each heating tube 20P may be made greater than in the heating step to the reduction temperature (S4). In this embodiment, whether or not the substrate W has risen to the melting temperature due to heating in this step is estimated by first determining the time required for the substrate W to reach the melting temperature under the heating conditions, and then heating the substrate W under those conditions for the predetermined time, similar to the heating step to the reduction temperature (S4). When the temperature of the substrate W rises to the melting temperature, the solder present in the substrate W melts and soldering is performed.

[0049] Once the substrate W is soldered, the control device 60 stops the heater 20 and stops heating the substrate W (S10). When the heater 20 stops, the temperature of the plate 18 and thus the substrate W decreases. In this embodiment, in order to accelerate the decrease in the temperature of the substrate W, after the heating of the substrate W stops, the control device 60 operates each support pin 31, thereby lowering the plate 18 and setting the plate 18 to the cooling position (S11). Here, the cooling position is the position where the temperature of the substrate W placed on the plate 18 is brought close to the ambient temperature of the reflow apparatus 1, and is typically the position where the plate 18 is in contact with the cooling block 12C. When the temperature of the substrate W drops below the temperature at which the molten solder solidifies, the solder solidifies and a solder-bonded substrate is manufactured. Once a solder-bonded substrate is manufactured, the lid 14 of the chamber 10 is opened at any time and the solder-bonded substrate is removed from the chamber 10 (S12). This completes the manufacturing of the soldered circuit board.

[0050] As described above, the reflow apparatus 1 according to this embodiment has the following effects. Each of the multiple heating tubes 20P has a different diameter (i.e., circumference) and is arranged in a nested manner, and is capable of outputting different amounts of heat from each other and the amount of heat output can be changed, so the output can be changed according to the required amount of heat, and the occurrence of temperature unevenness can be suppressed. In addition, since the heating tubes 20P with relatively large circumferences are divided in the circumferential direction, the temperature controllable area can be subdivided, enabling fine-grained temperature control. Furthermore, when heating, the output of the outer heating tubes 20P is set to be greater than or equal to the output of the inner heating tubes 20P, and the output of the first heating tube 21 is set to be greater than the output of the fifth heating tube 25, so the output of the heating tubes 20P can be set to be greater on the outside where heat dissipation is easier, and the occurrence of temperature unevenness can be suppressed. Furthermore, when the reduction temperature is started to be maintained, the ratio of the output of the outer heating tubes 20P to the output of the inner heating tubes 20P is set to be set to be set, so the occurrence of temperature unevenness when transitioning from the heating process to the temperature maintenance process can be suppressed.

[0051] In the above description, it was assumed that each heating tube 20P is formed in a ring shape, but it is not limited to a ring shape. For example, it may be an elliptical ring, or a ring with polygons such as a triangle, quadrilateral (including rectangles and rhombuses), pentagon, hexagon, or octagon. As an example, Figures 5(A) and 5(B) show an embodiment in which each heating tube 20P is a rectangular ring.

[0052] The heater 20A shown in the schematic plan view of Figure 5(A) has a first heating tube 21A, a second heating tube 22A, a third heating tube 23A, a fourth heating tube 24A, and a fifth heating tube 25A, each formed in a rectangular ring shape. These multiple heating tubes 21A, 22A, 23A, 24A, 25A, and the corresponding heating tubes shown in Figure 5(B) later are collectively referred to as heating tubes 20P when referring to their common configuration or characteristics, similar to the heating tubes 20P in heater 20 (see Figure 2). Each heating tube 20P in the heater 20A according to this modified example is configured similarly to the corresponding heating tubes 20P in heater 20 (see Figure 2), except that the shape and division configuration differ, and including the fact that the output can be independently set and changed.

[0053] The first heating tube 21A, the second heating tube 22A, the third heating tube 23A, the fourth heating tube 24A, and the fifth heating tube 25A are similar in shape but have different circumferences, and are typically arranged in a nested manner so that their centroids coincide. Each heating tube 20P in the heater 20A is divided circumferentially near the midpoint of one of the two pairs of opposing sides. The divided pairs of sides in each heating tube 20P of the heater 20A are staggered so that they are offset by 90 degrees between adjacent heating tubes 20P. The heater 20A configured in this way is suitable when the plate 18 (see Figure 1) is rectangular, and is also suitable for processing a rectangular substrate W (see Figure 3). Furthermore, when the heater 20A is applied, the base body 12, the holes 13H in the wall body 13, and the lid body 14 shown in Figure 3 should also be rectangular.

[0054] The heater 20B shown in the schematic plan view of Figure 5(B) has a first heating tube 21B, a second heating tube 22B, a third heating tube 23B, a fourth heating tube 24B, and a fifth heating tube 25B, each formed in a rectangular ring shape, and these are collectively referred to as heating tubes 20P. Each heating tube 20P in the heater 20B according to this modified example is configured similarly to each heating tube 20P in the heater 20A (see Figure 5(A)), except that the manner of division in the circumferential direction is different. Each heating tube 20P in the heater 20B is divided in the circumferential direction at the four corners of the rectangle. Therefore, each heating tube 20P in the heater 20B is divided into four equal parts. With the configuration of the heater 20B according to this modified example, straight tubes without bends can be used for the divided parts of each heating tube 20P, thus simplifying the configuration.

[0055] In the above description, it is assumed that the reflow apparatus 1 is equipped with a chamber 10. However, if it is not necessary to form a processing space 11 when processing a substrate, the chamber 10 does not need to be provided (i.e., it can be omitted). In this case, it is sufficient to have a configuration equivalent to the floor body 12 on which the heater 20 is installed. Also, in the above description, it is assumed that the apparatus is equipped with a gas supply unit 40 and an exhaust unit 50. However, if at least one of the gas supply unit 40 and the exhaust unit 50 is not used, the unused configuration does not need to be provided (i.e., it can be omitted).

[0056] In the above explanation, it was assumed that the annular first heating tube 21, second heating tube 22, third heating tube 23, fourth heating tube 24, and fifth heating tube 25, each with a different diameter, are arranged concentrically. However, if they are arranged in a nested manner, their centers may be offset. Similarly, for the rectangular heating tubes 20P in heaters 20A and 20B, their centroids may be offset if they are arranged in a nested manner.

[0057] In the above description, it is assumed that the first heating tube 21 is divided into four parts in the circumferential direction, the second heating tube 22 and the third heating tube 23 are divided into two parts in the circumferential direction, and the fourth heating tube 24 and the fifth heating tube 25 are not divided in the circumferential direction. However, whether or not each heating tube 20P is divided in the circumferential direction, and the number of divisions if it is divided, can be appropriately determined according to the purpose. For example, the number of divisions in the circumferential direction of the heating tube 20P is not limited to two or four divisions, but may be three, five, six, eight, or any other number. Also, the manner of division is not limited to equal divisions, but may be divided in a desired ratio. The same applies to each heating tube 20P in heaters 20A and 20B.

[0058] In the above explanation, it was assumed that the inert gas supplied in the gas supply unit 40 is nitrogen gas (N) and the reducing gas is formic acid gas (F). However, the inert gas may be other than nitrogen gas (N), such as argon gas. Also, the reducing gas may be a carboxylic acid gas other than formic acid, or hydrogen gas, etc.

[0059] In the above explanation, whether or not the substrate W has risen to the reduction temperature or melting temperature during the heating process is estimated by heating the substrate W under those conditions for a predetermined time. However, it is also possible to provide a sensor to detect the temperature of the substrate W or plate 18 and make a determination based on the temperature detected by the sensor.

[0060] In the above explanation, it was assumed that each of the multiple heating tubes 20P constituting the heater 20 has a different circumference and is arranged in a nested manner, and that it is capable of outputting different amounts of heat from each other, and that the amount of heat output can be changed. This configuration of the heater 20 can also be applied to the cooler, for example, each of the cooling blocks 12C may have a different circumference and be arranged in a nested manner, and that it is capable of outputting different amounts of cooling heat (i.e., cooling heat amount or amount of heat that can be removed), and that the amount of cooling heat output can be changed. The same applies to the heaters 20A and 20B.

[0061] In the above explanation, the support member was assumed to be a plate 18 that supports the entire lower surface of the substrate W. However, it may also be a jig such as an outer edge holding chuck or frame that supports all or part of the edges of the substrate W. In this case, radiant heat from the heaters 20, 20A, and 20B will be directly irradiated onto the substrate W.

[0062] In each of the embodiments described above, the term "processor" refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.). Furthermore, the processor operations in each of the above embodiments may not be performed by a single processor, but may also be performed by multiple processors located in physically separate locations working together. Also, the order of the processor operations is not limited to the order described in each of the above embodiments, and may be changed as appropriate. Furthermore, the above program may be provided on a computer-readable non-temporary recording medium such as a USB (Universal Serial Bus) memory, flexible disk, or CD-ROM (Compact Disc Read Only Memory), or it may be provided online via a network such as the Internet. In this case, the program recorded on the computer-readable non-temporary recording medium is usually transferred to and stored in memory or storage. This program may also be provided, for example, as a standalone application software, or it may be incorporated into the software of each device as a function of that device. The program disclosed herein is available as a program product. A program product includes any form of product for providing the program. For example, a program product includes a program provided via a network such as the Internet, and non-temporary computer-readable recording media such as CD-ROMs and DVDs on which the program is stored.

[0063] In the above description, a reflow apparatus 1 as a heating device and a method for manufacturing a soldered object were explained using the figures as illustrative embodiments. The configuration, structure, number, arrangement, shape, material, etc. of each part in the above description are not limited to the above specific examples, and those that are appropriately selected by those skilled in the art are also included in the scope of the present invention as long as they encompass the gist of the present invention. [Explanation of symbols]

[0064] 1. Reflow apparatus (heating device) 18. Plate (support member) 20, 20A, 20B heater 20P heating tube (heating element) 60 Control device W substrate (object to be heated)

Claims

1. A support member that supports the object to be heated, A heater for heating an object supported by the support member, or the support member supporting the object to be heated, comprising: a heater having a plurality of annular heating elements, each of which has a different circumference and is arranged in a nested manner, and which is capable of outputting different amounts of heat from each other and whose output amounts of heat can be changed; heating device.

2. The support member is a plate-shaped member on which the object to be heated is placed. The heater heats the plate-shaped member. The heating device according to claim 1.

3. At least one of the heating elements is divided in the circumferential direction. The heating device according to claim 1.

4. It includes a control device that controls the output of each of the aforementioned heating elements. A heating device according to any one of claims 1 to 3.

5. The control device controls the output of each of the heating elements such that the output of the outer heating element is greater than or equal to the output of the inner heating element, and the output of the outermost heating element is greater than the output of the innermost heating element. The heating apparatus according to claim 4.

6. When the control device determines that the temperature of the object to be heated has reached a predetermined temperature, it increases the ratio of the output of the outer heating element to the output of the inner heating element. The heating apparatus according to claim 4.

7. A method for manufacturing an object that has been soldered using the heating device described in claim 5, A step of supplying the object to be heated, which has solder, to the support member, A step of generating heat from the heating element to raise the temperature of the object to be heated to a first predetermined temperature, wherein the first predetermined temperature is below the melting point of the solder and is a temperature at which oxides present in the object to be heated can be reduced. After the temperature of the object to be heated has risen to the first predetermined temperature, the ratio of the output of the outer heating element to the output of the inner heating element is increased to maintain the temperature of the object to be heated at the first predetermined temperature, A step of supplying a reducing gas to the object to be heated, which is maintained at the first predetermined temperature, The process includes the step of supplying the reducing gas to the object to be heated, then increasing the output of the heating element to raise the object to be heated to a second predetermined temperature above the melting point of the solder, thereby performing solder joining. A method for manufacturing soldered objects.

Images