Heating device for reflow observation and X-ray reflow observation system

Abstract

To provide a heating device for reflow observation that can observe an object to be heated at high magnification by bringing an X-ray head close to the object. [Solution] This device is mounted on an X-ray observation device 100 and heats an object to be observed, and includes a substantially box-shaped heating chamber 10 that forms a heating space inside, a bottom cover 10 made of an X-ray transparent material and provided on the bottom surface of the heating chamber 10, a heating means 30 that is located inside the heating chamber 10 and heats the object to be heated 90 by radiating infrared rays, a mounting table 40 that is located inside the heating chamber 10 and made of an X-ray transparent material and on which the object to be heated 90 is placed, and a top cover 50 that is located on the top surface of the heating chamber 10 and made of a quartz plate 51 with a gold-plated bottom surface.

Description

[Technical Field]

[0001] The present invention relates to a heating device for reflow observation and an X-ray reflow observation system. [Background technology]

[0002] Conventionally, simulators for observing the reflow state of solder have been used, which heat an object such as solder using a ceramic heater, hot air, etc., and observe the temperature changes at various points on the object. This type of device is used particularly for the purpose of inspecting the reflow state of solder in semiconductor devices. For example, Patent Document 1 discloses a device for imaging an object inside a reflow furnace, which is a reflow furnace observation device that includes a reflow furnace and a visible light camera that images the object through an observation window provided in the reflow furnace.

[0003] With the miniaturization of the latest semiconductor devices, at least the upper and lower surfaces of the heating device are made of an X-ray transparent material in order to observe the solder reflow state in detail, and the reflow state of the heated object is observed through an X-ray device (Patent Documents 2 to 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-177069 [Patent Document 2] Japanese Patent Application Publication No. 2018-015803 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-017753 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-123858 [Patent Document 5] Japanese Patent Application Laid-Open No. 2005-353712 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as semiconductor components become smaller, it is necessary to increase the image magnification during inspection (100 times or more) in order to inspect the minute details of solder reflow. For this reason, a method has been devised in which an X-ray fluoroscopic image of the sample (heated object) is captured using a two-dimensional X-ray detector with a large number of pixels and then digitally enlarged. However, because the X-ray source is not a perfect point but has a certain size, the greater the distance from the heated object to the X-ray detector, the blurrier the fluoroscopic image becomes, and the image quality deteriorates. Further digital enlargement of this image further reduces the image quality. For this reason, to maintain good image quality even with a magnification of 100x or more, the X-ray detector must be placed very close to the heated object, within a few millimeters. However, placing a large X-ray head close to the heated object causes mechanical interference, and there is a risk of the X-ray head being heated and damaged if placed close to reflowed solder at temperatures of several hundred degrees.

[0006] The present invention aims to solve the above problems and provide a heating device for reflow observation (reflow simulator) that can observe a heated object at high magnification by bringing an X-ray head close to the object, and an X-ray reflow observation system that includes this heating device for reflow observation. [Means for solving the problem]

[0007] In order to solve the above problems, the heating device for reflow observation of the present invention comprises: A device that is mounted on an X-ray observation device and heats an object to be observed, a substantially box-shaped heating chamber that forms a heating space therein; a lower cover provided on the lower surface of the heating chamber and made of an X-ray transparent material; a heating means disposed inside the heating chamber and configured to heat the object by radiating infrared rays; a mounting table that is disposed inside the heating chamber and is made of an X-ray transparent material and on which the object to be heated is placed; an upper cover provided on the upper surface of the heating chamber and made of a quartz plate with a gold-plated lower surface; The present invention is characterized by comprising:

[0008] With this configuration, the quartz plate and gold-plated layer of the top cover are X-ray transparent, allowing for X-ray transillumination of the heated object, while reflecting infrared rays from the heating means toward the heated object, allowing for effective heating of the heated object while reducing heating of the X-ray head.In addition, because the quartz plate has little thermal deformation, the X-ray head can be brought closer to the heated object without mechanical interference with the quartz plate, allowing for high-magnification observation of the heated object.

[0009] The mounting table is preferably made of a transparent quartz plate. With this configuration, even if the object to be heated is placed close to the top cover and the X-ray head, infrared light from the heating means can pass through the mounting table and heat the object effectively. In addition, the mounting table has good X-ray transparency, allowing for good X-ray fluoroscopic observation of the object to be heated.

[0010] The mounting table may have a lifting mechanism. With this configuration, even if the object to be heated is of a different height, the height of the lifting mechanism can be adjusted to bring the object close to the back surface of the top cover, and the object can be brought close to the X-ray head and photographed at high magnification.

[0011] The heating means is preferably a quartz heater that emits infrared rays from a heating element provided inside a quartz glass tube, and has a reflective film on the back surface of the quartz glass tube so as to reflect the infrared rays from the heating element toward the object to be heated. This configuration allows the object to be heated efficiently.

[0012] The heating device for reflow observation may further include a cooling nozzle that blows air from the side onto the surface of the top cover to cool it.

[0013] With this configuration, the cooling nozzle can be positioned so that it does not interfere with the X-ray detector located close to the top cover, and the surface of the top cover can be cooled, thereby preventing the X-ray head from being heated by heat from the top cover.

[0014] The heating device for reflow observation may further include a temperature sensor that detects the temperature of the object to be heated, and a control unit that controls the output of the heating means based on the temperature detected by the temperature sensor.

[0015] With this configuration, the object to be heated can be heated according to a predetermined temperature profile, and the reflow state and other conditions can be observed with an X-ray observation device.

[0016] The X-ray reflow observation system of the present invention comprises: the heating device for reflow observation; an X-ray source that is disposed under the bottom cover of the heating apparatus for reflow observation and irradiates the object to be heated with X-rays that pass through the bottom cover and the mounting table; an X-ray detector disposed on the top cover of the heating apparatus for reflow observation, for detecting X-rays transmitted through the object to be heated; The present invention is characterized by comprising:

[0017] With this configuration, the reflow state of the heated object can be observed at high magnification by bringing the X-ray head of the X-ray fluoroscopy observation device close to the heated object being heated by the heating device for reflow observation and taking an image. [Effects of the Invention]

[0018] According to the heating device for reflow observation of the present invention, the quartz plate and gold-plated layer of the top cover are X-ray translucent, allowing for X-ray transillumination of the heated object, while reflecting infrared rays from the heating means toward the heated object, thereby effectively heating the heated object while reducing heat applied to the X-ray head. Furthermore, because the quartz plate has little thermal deformation, the X-ray head can be brought closer to the heated object without mechanical interference with the quartz plate, allowing for high-magnification observation of the heated object.

[0019] Furthermore, according to the X-ray reflow observation system of the present invention, the reflow state of the heated object can be observed at high magnification by bringing the X-ray head of the X-ray fluoroscopy observation device close to the heated object being heated by the heating device for reflow observation and taking an image. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic perspective view showing a heating apparatus for reflow observation according to an embodiment of the present invention; [Figure 2] 2 is an enlarged view showing a heating chamber of the heating device of FIG. 1. FIG. [Figure 3] 3 is a schematic cross-sectional view of the heating chamber and its vicinity taken along the line AA in FIG. 2. [Figure 4] 3 is a schematic cross-sectional view of the heating chamber and its vicinity shown in FIG. 2 . [Figure 5] FIG. 2 is a control block diagram of the heating device for reflow observation in FIG. [Figure 6] 1 is a schematic diagram showing an X-ray reflow observation system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] (heating device) A heating apparatus for reflow observation (hereinafter also simply referred to as "heating apparatus") 1 according to an embodiment of the present invention will be described below with reference to FIGS. 1, the heating device 1 includes a heating chamber 10, a lower cover 20, a heating means 30, a mounting table 40, an upper cover 50, a cooling nozzle 60, a temperature sensor 70, and a control unit 80 (see FIG. 5). In FIG. 1, reference numeral 120 denotes an X-ray detector 120, which will be described later.

[0022] The heating chamber 10 is a housing having a substantially box shape and forming a heating space therein. In this embodiment, as shown in the enlarged view of FIG. 2, the heating chamber 10 includes a heat-insulating front panel 11, a back panel 12, a left panel 13, a right panel 14, and a lower base plate 15 (see FIG. 1). The heating chamber 10 is sealed by attaching a bottom cover 20 and a top cover 50 (described later). As shown in FIG. 1, pipes 17 are connected to the front panel 11 and the back panel 12 of the heating chamber 10 via joints 16, and the other end of each pipe 17 is attached to an external connection joint 18. This allows for the supply of a purge gas, such as an inert gas, which prevents chemical reactions such as oxidation of the heated object, or a reactive gas, which causes a chemical reaction, into the heating chamber 10. The on / off control of the purge gas and reactive gas is controlled by a control unit 80 (described later) via an external solenoid valve (not shown).

[0023] The bottom cover 20 is provided on the bottom surface of the heating chamber 10 and is made of an X-ray transparent material. In this embodiment, the bottom cover 20 is made of an X-ray transparent thin metal plate or quartz plate, and is fitted into the opening of the substrate 15 as shown in Figure 3 or 4. The bottom cover 20 seals the bottom of the heating chamber 10 and also enables X-ray fluoroscopic observation.

[0024] The heating means 30 is disposed inside the heating chamber 10 and heats the object 90 to be heated by radiating infrared rays. In this embodiment, the heating means 30 is composed of two quartz heaters 30a, 30b (collectively referred to as "quartz heaters 30") disposed in parallel. As conceptually shown in FIG. 4, each quartz heater 30 radiates infrared rays from a coil-shaped heating wire (not shown) provided inside a quartz glass tube (30). The quartz glass tube (30) has a reflective film 31 on the rear surface thereof, and is configured to reflect infrared rays IR from the heating wire (not shown) toward the object 90 to be heated.

[0025] The mounting table 40 is disposed inside the heating chamber 10 and is made of an X-ray transparent material, on which the object to be heated 90 is placed. In this embodiment, the mounting table 40 is made of a transparent quartz plate 41. With this configuration, as shown in FIG. 3, infrared rays IR from the quartz heaters 30a and 30b can pass through the mounting table 40 and effectively heat the object to be heated 90. Furthermore, since the mounting table 40 has good X-ray transparency, the object to be heated 90 can be effectively observed through X-rays. 2 and 3, the mounting table 40 has an elevating mechanism 42. As shown in FIG. 2 and FIG. 3, the elevating mechanism 42 includes holding members 43a and 43b (collectively referred to as "holding members 43") that hold the quartz plate 41 from the left and right, respectively, two guide rods 44 and two guide bushes 45 that guide each holding member 43 so that it can move up and down (four in total), one adjusting screw 46 that manually moves the holding member 43 up and down (two in total), and two springs 47 that urge the holding member 43 downward (four in total). By adjusting the height of the elevating mechanism 42, the object 90 can be brought close to the rear surface of the top cover 50 (quartz plate 51), and the object 90 can be brought close to the X-ray detector 120 (see FIG. 1), allowing high-magnification imaging of objects 90 of different heights.

[0026] The top cover 50 is provided on the top surface of the heating chamber 10 and is made of a transparent quartz plate 51 with a gold-plated layer 51a on its underside. This gold-plated layer 51a is transparent to X-rays while being thick enough to reflect infrared rays from the heating means 30 and the object to be heated 90. Note that in FIGS. 1 and 2, the quartz plate 51 is cut away so that the interior of the heating chamber 10 can be seen. In this embodiment, the quartz plate 51 is fixed to a frame 52 with eight clamping brackets 53. L-shaped brackets 54 are attached to the front and rear surfaces of the frame 52, and fixing screws 55 are engaged with the L-shaped brackets 54. These fixing screws 55 screw into threaded holes provided in receiving brackets 19 on the heating chamber 10 side, thereby fixing the top cover 50 to the heating chamber 10.

[0027] The cooling nozzle 60 is a unit that cools the surface of the top cover 50 by blowing air from the side. As shown in FIG. 1, the cooling nozzle 60 is positioned so as not to interfere with the X-ray detector 120, which is located close to the top cover 50. The cooling nozzle 60 comprises a straight hollow tube 61 having a number of blowing holes 61a arranged in a row on its side, and a pair of holders 62 that hold the hollow tube 61 horizontally. A pipe 63 is connected to the hollow tube 61, and clean air is supplied from a clean air supply source (not shown) via an electromagnetic valve 64. The clean air is blown into the gap between the surface of the top cover 50 and the X-ray detector 120, cooling the surface of the top cover 50. This reduces heating of the X-ray detector 120 due to heat from the top cover 50.

[0028] The temperature sensor 70 is a sensor that measures the ambient temperature near the heating means 30 in order to control the temperature of the heated object 90, and any known sensor can be used. In this embodiment, a thermocouple, which is a contact temperature sensor, is used, as shown in Fig. 1 or 2. The temperature sensor 70 is not limited to a thermocouple, and may be a thermistor or a resistance thermometer, or a non-contact sensor such as an infrared temperature sensor.

[0029] The control unit 80 is a unit that controls the output of the heating means 30 (quartz heaters 30a, 30b) based on the temperature detected by the temperature sensor 70. In this embodiment, the control unit 80 also controls the clean air supplied to the cooling nozzle 60 and the purge gas supplied to the heating chamber 10. As conceptually shown in FIG. 5 , the control unit 80 includes a CPU 81 that operates according to a predetermined program, an input interface 82 for the temperature sensor 70, an output interface 83 for the heating means 30, a cooling air valve interface 84, a purge gas valve interface 85, an operation unit 86, and the like. With this configuration, the object to be heated 90 is heated according to a predetermined temperature profile, and the reflow state and the like during this heating can be observed by X-ray.

[0030] (X-ray reflow observation system) FIG. 6 is a conceptual diagram showing an X-ray reflow observation system 2 according to this embodiment. The X-ray reflow observation system 2 of this embodiment is composed of the heating device 1 mounted on the sample stage 101 of a general-purpose X-ray observation device 100, and an X-ray source 110 and an X-ray detector 120 of the X-ray observation device 100.

[0031] The X-ray source 110 is a unit disposed below the bottom cover 20 of the heating device 1, and irradiates the object to be heated 90 with X-rays that pass through the bottom cover 20 and the mounting table 40. A known X-ray source can be used for this X-ray source 110. For example, as described in Patent Document 4, a source that excites a target by irradiating the target with a converged electron beam to generate X-rays may be used.

[0032] The X-ray detector 120 is disposed on the top cover 50 of the heating device 1, and is a unit that detects X-rays that have passed through the object to be heated 90. This X-ray detector 120 can also be a known one. For example, it consists of a plate-shaped scintillator that converts X-rays into visible light, and an imaging element such as a CCD attached to it. However, in this X-ray reflow observation system 2, since the X-ray fluoroscopic image of the object to be heated 90 is digitally magnified to a high magnification, it is preferable that the X-ray detector 120 have a large number of pixels. In addition, a larger imaging surface size of the X-ray detector 120 is preferable because it can image the entire object to be heated at once.

[0033] (Operation and Actions) Next, the operation and behavior of the X-ray reflow observation system 2 including the heating device 1 of this embodiment configured as described above will be described. First, the sample stage 101 of the X-ray observation device 100 shown in Fig. 6 is lowered to separate the heating device 1 from the X-ray detector 120, thereby creating space above the heating device 1. In this state, the knobs of the two fixing screws 55 (see Fig. 1) shown in Fig. 2 are loosened to remove the top cover 50 consisting of the quartz plate 51 and the frame 52 from the heating chamber 10. In this state, the object to be heated (e.g., a semiconductor circuit before reflow) 90 is manually placed on the mounting table 40 in the heating chamber 10. Next, the height is adjusted by turning the adjustment screws 46 on the two holding members 43a, 43b located on the left and right of the lifting mechanism 42 of the mounting table 40. This adjusts the height of the top surface of the object to be heated 90 to protrude a predetermined height (e.g., 1 mm lower than the thickness of the frame 52) from the top end of the heating chamber 10. As a result, when the top cover 50 is attached to the heating chamber 10, the gap between the top surface of the object to be heated 90 and the bottom surface of the quartz plate 51 of the top cover 50 will be approximately 1 mm. After adjustment, the top cover 50 is attached to the heating chamber 10, and the knobs of the two fixing screws 55 (see Figure 1) are tightened.

[0034] Next, the sample stage 101 of the X-ray observation device 100 shown in Fig. 6 is raised to bring the heating device 1 close to the X-ray detector 120. For example, the distance between the upper surface of the quartz plate 51 of the upper cover 50 of the heating device 1 and the lower surface of the X-ray detector 120 is set to about 2 to 3 mm. Furthermore, the solenoid valve 64 for supplying clean air to the cooling nozzle 60 is opened by operating the operating means 86 (see FIG. 5) of the control unit 80, and cooling of the upper surface of the upper cover 50 begins. Also, if necessary, the supply valve (not shown) for a purge gas (such as an inert gas) to the heating chamber 10a is opened by operating the operating means 86 (see FIG. 5), and the heating chamber 10a is purged.

[0035] The heating process program (target temperature profile) to be executed is selected and the process start operation is performed using the operation means 86 of the control unit 80. Then, electricity is supplied to the two quartz heaters 30a and 30b, which are the heating means 30, and the heating process begins. In this heating process, the control unit 80 controls the outputs of the quartz heaters 30a and 30b so that the temperature detected by the temperature sensor 70 conforms to a predetermined target temperature profile.

[0036] In this state, X-ray photography of the object to be heated 90 is performed using the X-ray observation device 100. That is, the X-ray source 110 is operated to generate X-rays XR. These X-rays XR pass through the bottom cover 20 and the mounting table 40 of the heating device 1 mounted on the sample stage 101 and are irradiated onto the object to be heated 90. The X-rays XR that have passed through the object to be heated 90 further pass through the top cover 50 and are incident on the X-ray detector 120, and an X-ray fluoroscopic image of the object to be heated 90 is formed on the image plane of the X-ray detector 120. Still images or videos of this X-ray fluoroscopic image can be captured or viewed on a monitor.

[0037] When the heating process and X-ray observation and photography are completed, for example, the sample stage 101 of the X-ray observation device 100 is lowered to separate the heating device 1 from the X-ray detector 120, and the heating chamber 10 is cooled by air cooling using purged air. After sufficient cooling, the knobs of the two fixing screws 65 are loosened to remove the top cover 50 from the heating chamber 10, and the object to be heated 90 is removed.

[0038] Since the heating device 1 of this embodiment is a test device, it is configured so that the loading and unloading of the object to be heated 90, the raising and lowering adjustment of the mounting table 40, etc. are performed manually. However, in a mass production device, these operations may be performed automatically by the operating means of the control unit 80. Also, in the X-ray reflow observation system 2, the control unit 80 may cooperate with the X-ray observation device 100 so that each operation can be performed from the operation unit of the X-ray observation device 100.

[0039] According to the heating apparatus for reflow observation 1 of this embodiment, the quartz plate 51 and gold plating layer 51a of the top cover 50 are X-ray translucent, allowing X-ray translucent observation of the object to be heated 90, while reflecting infrared rays from the heating means 30 toward the object to be heated 90, thereby effectively heating the object to be heated 90 while reducing heating of the X-ray detector 120. Furthermore, because the quartz plate 51 has little thermal deformation, the X-ray detector 120 can be brought closer without mechanical interference with the quartz plate 51, allowing high-magnification observation of the object to be heated 90. Furthermore, according to the X-ray reflow observation system 2 of the present invention, the object to be heated 90 being heated by the heating device for reflow observation 1 is imaged by bringing the X-ray detector 120 of the X-ray observation device 100 close to the object to be heated 90, thereby making it possible to observe the reflow state of the object to be heated 90 at high magnification.

[0040] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

[0041] For example, in the above embodiment, the heating chamber 10 is structured to have one outer wall each on the front, back, left, right and bottom sides, but this is not limited to this, and it may have a double structure in which an insulating or X-ray transparent partition is further added on the inside to improve insulation.

[0042] In addition, in the above embodiment, the material of the mounting table 40 is a transparent quartz plate 41, but any material that is X-ray transparent may be used. For example, if the heated object 90 is heated by thermal conduction, an X-ray transparent metal may be used.

[0043] Furthermore, in the above embodiment, the lifting mechanism 42 for the mounting table 40 is provided, but if the thickness of the object to be heated 90 is constant and no adjustment is required, for example, the lifting mechanism 42 may not be provided.

[0044] Furthermore, in the above embodiment, the quartz heaters 30a and 30b are used as the heating means 30, but the present invention is not limited to this and any means that can heat to a temperature sufficient for reflow may be used.

[0045] In addition, in the above embodiment, a cooling nozzle 60 is provided that cools the surface of the top cover 50 by blowing air from the side, but in cases where, for example, the heating temperature of the heated object 90 is low and the temperature of the top cover 50 is low, the cooling nozzle 60 does not have to be used.

[0046] In the above embodiment, the control unit 80 was used to control the output of the heating means 30 based on the temperature detected by the temperature sensor 70, and the cooling air, purge gas, etc. were also controlled by the operation means 86 of the control unit 80. However, depending on the purpose of use, the control unit 80 may be configured to only control the output of the heating means 30, or all operations may be performed manually without using the control unit 80. [Industrial Applicability]

[0047] The heating device for reflow observation 1 and the X-ray reflow observation system 2 according to the present invention can be widely used in the industrial fields of semiconductor and automobile part manufacturing. [Explanation of symbols]

[0048] 1. Heating device for reflow observation (heating device) 2 X-ray reflow observation system 10 Heating chamber 10 11 Front plate 12 Back plate 13 Left side plate 14 Right side plate 15 PCB 16 Joints 17 Piping 18 External connection joint 19 Bracket 20 Bottom cover 30 Heating means (quartz heater) 30a, 30b Quartz heater 31 Reflective film 40 Mounting table 41 Quartz plate 42 Lifting mechanism 43, 43a, 43b Holding member 44 Guide rod 45 Guide bush 46 Adjustment screw 47 Spring 50 Top cover 51a Gold plating layer 51 Quartz plate 52 Frame 53 Clamp 54 L bracket 55 fixing screw 60 Cooling nozzle 61a Air outlet 61 Hollow tube 62 Holding part 63 Piping 64 Solenoid valve 70 Temperature Sensor 80 Control Unit 81 CPU 82 Temperature sensor input interface 83 Heating means output interface 84 Cooling Air Valve Interface 85 Purge Gas Valve Interface 86 Operating means 90 Heated object 100 X-ray observation device 101 Sample stage 110 X-ray source 120 X-ray detector IR Infrared X-ray

Claims

1. A device mounted on an X-ray observation device to heat an object to be observed, a substantially box-shaped housing that defines a heating chamber therein; a lower cover provided on a lower surface of the heating chamber and made of an X-ray transparent material; a heating means disposed in the heating chamber and configured to heat the object by radiating infrared rays; a mounting table that is disposed in the heating chamber and is made of an X-ray transparent material and on which the object to be heated is placed; an upper cover provided on the upper surface of the heating chamber and made of a quartz plate with a gold-plated lower surface; A heating device for reflow observation, comprising:

2. 2. The heating apparatus for reflow observation according to claim 1, wherein said mounting table is made of a transparent quartz plate.

3. 3. The heating apparatus for reflow observation according to claim 2, wherein the mounting table has a lifting mechanism.

4. 3. The heating device for reflow observation according to claim 2, wherein the heating means is a quartz heater that radiates infrared rays from a heating element provided inside a quartz glass tube, and the quartz glass tube has a reflective film on the back surface thereof so as to reflect the infrared rays from the heating element toward the object to be heated.

5. 2. The heating apparatus for reflow observation according to claim 1, further comprising a cooling nozzle for blowing air from the side onto the surface of said top cover to cool it.

6. 2. The heating device for reflow observation according to claim 1, further comprising: a temperature sensor for detecting the temperature of the object to be heated; and a control unit for controlling the output of the heating means based on the temperature detected by the temperature sensor.

7. a heating device for reflow observation according to claim 1; an X-ray source disposed under the bottom cover of the heating apparatus for reflow observation, which irradiates the object to be heated with X-rays passing through the bottom cover and the mounting table; an X-ray head disposed on the top cover of the heating apparatus for reflow observation, for detecting X-rays transmitted through the object to be heated; An X-ray reflow observation system comprising:

Images