JP2018015803A - X-ray transparent soldering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow monitoring with a moving image of behavior of molten solder during reflow soldering of a printed circuit board printed with solder paste and implemented with an electronic component in vacuum atmosphere or high-pressure atmosphere using an X-ray reflow simulator device.SOLUTION: An X-ray transparent soldering device includes a container 40 excellent in X-ray transparency, having a base 42 and a cover 44 formed of a high-thermal conductive metal and capable of vertically opening and closing; and heat-resistant packing 50 inserted into a clearance between the base 42 and the cover 44 and having a function for preventing gas leakage. The X-ray transparent soldering device itself does not have a heat source and is used with a device having a heat source.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray transparent soldering apparatus, and in particular, can be soldered in a vacuum atmosphere or a high-pressure atmosphere, which is suitable for observing the behavior of molten solder during reflow soldering. As such, it relates to an X-ray transparent soldering apparatus having no heating source.

  As shown in Patent Documents 1 to 3, an X-ray reflow simulator device developed by the applicant and obtained a patent is known. According to this X-ray reflow simulator device, an object such as a sample is heated to a target temperature or according to a preset temperature profile, and the state change of the X-ray transmission image is observed in real time, or the temperature change By recording or moving images, it becomes possible to analyze the causes of the occurrence of defects in solder joints, the behavior of various materials due to temperature changes, and the like.

  Patent Document 4 also proposes a technique for inspecting the presence or absence of voids in a solder layer of a circuit module using X-rays.

Japanese Patent No. 5290030 Japanese Patent No. 4959844 Japanese Patent No. 5818106 JP 2012-84791 A

  Conventionally, however, it has been difficult to inspect the behavior of molten solder during reflow soldering in a vacuum atmosphere or high-pressure atmosphere of a printed circuit board on which a solder paste is printed and an electronic component is placed.

  The present invention has been made to solve the above-mentioned conventional problems. The behavior of molten solder during reflow soldering in a vacuum atmosphere or high-pressure atmosphere of a printed circuit board on which a solder paste is printed and an electronic component is placed is described as X. It is an object to make it possible to observe a moving image with a line inspection apparatus.

  The present invention has a base and cover made of a metal having excellent X-ray transparency and high thermal conductivity, and a container that can be opened and closed vertically, and a gas leak inserted into a gap between the base and the cover. A heat-resistant packing having a function to prevent, having no heat source itself, and being used together with an apparatus having a heat source. It is.

  Here, the container can be sealed by atmospheric pressure applied to the fixture or the outside of the container.

  In addition, since the central portion of the cover swells upward, a space for placing the soldering object can be formed between the central portion of the cover and the base.

  In addition, the upper surface of the base is flat and can be set with the substrate to be soldered in close contact with the inside, and the thickness increases as it goes to the periphery. A difficult structure can be obtained.

  In addition, a pipe capable of making the inside of the container vacuum or high pressure can be provided and connected to a vacuum pump or a compressor.

  In addition, a thermocouple can be inserted inside the container, and an external heating source can be controlled by the measured temperature of the thermocouple.

  In addition, a magnesium alloy or an aluminum alloy can be used as the metal having excellent X-ray permeability and high thermal conductivity.

  According to the present invention, the soldering apparatus according to the present invention that does not have a heating source can be applied to the space where hot air projects from above and below the X-ray reflow simulator apparatus described in Patent Documents 1 to 3, as if it were a sample substrate. By inserting, the solder paste printed circuit board installed in this soldering device can be reflow soldered mainly by heat conduction heating during vacuum reflow, and by heat conduction heating and convection heating during high pressure reflow, It is possible to photograph and observe a moving image in which the enlargement ratio is increased with X-rays of the behavior of the molten solder during reflow soldering in vacuum or reflow soldering under high pressure. Therefore, it becomes possible to observe the behavior of molten solder in vacuum or high pressure, analysis of the cause of soldering defects such as voids, bridges, non-wetting, and blowholes due to humidity in the board, It is possible to conduct an experiment for countermeasures against these soldering defects, and it is easy to make effective countermeasures against defects.

Sectional drawing which shows embodiment of this invention Same top view The perspective view which similarly shows the thin part of a base Sectional drawing which shows the state which is heating this invention apparatus in an example of an X-ray reflow simulator apparatus Drawing substitute photograph which shows the external appearance of the Example of this invention Drawing substitute photo showing the disassembled state

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content described in the following embodiment and an Example. In addition, the constituent elements in the embodiments and examples described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in the so-called equivalent range. Furthermore, the constituent elements disclosed in the embodiments and examples described below may be appropriately combined or may be appropriately selected and used.

  As shown in FIG. 1 (cross-sectional view) and FIG. 2 (plan view), the present embodiment has a base 42 made of a metal having excellent X-ray transparency, such as magnesium alloy or aluminum alloy, and high thermal conductivity. A container 40 having a cover 44 that can be opened and closed vertically, and a heat-resistant Viton rubber or silicon rubber that is inserted into a gap between the base 42 and the cover 44 and has a function of preventing gas leakage, or made of metal. Packing (plate-like or O-ring-like) 50.

  The upper surface of the base 42 is a flat surface, and the printed wiring board 7 to be soldered can be set in close contact with the inside of the base 42, and the thickness of the body becomes thicker toward the periphery. The structure is also difficult to deform. As shown in FIG. 2 (plan view) and FIG. 3 (perspective view), the base 42 is provided with thin portions 42A in four directions, for example, 0 °, 90 °, 180 °, and 270 °. It is gradually getting thicker. This is to make it easier to accommodate a pipe 60 and a thermocouple 62, which will be described later, and to provide a space for allowing hot air that hits the central concave portion of the base 42 from below to escape to the side surface.

  A solder paste 10 is printed on the lands 9 of the printed wiring board 7, and an electronic component 8 to be reflow soldered is placed thereon.

  The center portion of the cover 44 bulges upward to form a space for placing the printed wiring board 7 to be soldered between the center portion of the cover 44 and the base 42. The cover 44 is also thickened as it goes to the periphery, and has a structure that does not easily deform even when the inside of the container 40 is in a vacuum or high pressure.

  The base 42 and the cover 44 can be sealed by, for example, a bolt 46 and a nut 48 disposed in the thin portion 42A. By accommodating the nut 48 in the thin portion 42A of the base 42, the container 40 can be set horizontally. Note that a fixing tool other than the bolt 46 and the nut 48 can be used. In particular, when the inside of the container 40 is evacuated, the bolt 46 and the nut 48 can be omitted.

  For example, an aluminum pipe 58 is inserted into the insertion opening 42B of the base 42 of the container 40, and a pipe 60 such as a rubber pipe for making the inside of the container 40 vacuum or high pressure is connected to the aluminum pipe 58. . The pipe 60 is connected to a vacuum pump or a high-pressure gas cylinder of nitrogen or a compressor, for example, so that the internal space of the container 40 can be made vacuum or high-pressure.

  Further, for example, the base 42 of the container 40 is provided with an insertion port 42C of a thermocouple 62 to be inserted inside the container 40, and the thermocouple 62 is attached to the printed wiring board 7 installed inside, for example. It is attached. An external heating source (for example, a hot air generating planar heater described later) is controlled by the measured temperature of the thermocouple 62.

  The aluminum tube 58 and the insertion ports 42B and 42C of the thermocouple 62 are filled with a heat-resistant adhesive such as silicon rubber and sealed. It is also possible to use a partition wall penetrating thermocouple as the thermocouple 62.

  FIG. 4 is a cross-sectional view showing a state in which the apparatus of the present invention is heated in an example of the X-ray reflow simulator apparatus described in Japanese Patent No. 4959844 (Patent Document 2) which has already been granted.

  In FIG. 4, 1 is a planar heater for generating hot air, 14 is a shield heat insulating part, 15 is a gas supply pipe, 20 is an X-ray generating part of an X-ray irradiation apparatus, 21 is an X-ray irradiation range, and 22 is a window part. , 23 is an X-ray receiving device, 27 is a sample chamber, 31 is a support, 31a is an exhaust port formed on, for example, a side surface of the support 31, 32 is a hot air blowing plate, and 32a is a hot air blowing hole.

  The planar heater 1 is installed vertically, and an insulating spacer 16 is inserted between the lower planar heater 1 and the container 40 according to the present invention in which the printed wiring board 7 is accommodated.

  The gas supply pipe 15 can be used by being fitted into a hot air blowing hole of the shielding heat insulating part 14.

  In the embodiment configured as described above, in order to heat the sample, a voltage is applied to the planar heater 1 while supplying a gas from the gas supply pipe 15. The voltage may be applied from the end of the planar heater 1 outside the window 22. The applied voltage may be direct current or alternating current. In the case of observation, it is also possible to perform temperature monitoring by installing a thermocouple in a site that does not hinder X-ray observation.

  As the temperature of the planar heater 1 rises, the temperature of the gas supplied from the gas supply pipe 15 also rises, hot air blows out from the hot air blowing holes 32a, and a heated swirling flow is generated in the sample chamber 27. Increase the temperature inside. Then, the temperature of the container 40 in which the printed wiring board 7 as a sample is also rapidly and uniformly increased in the surface, the solder paste 10 is melted, and the electronic component 8 and the copper land 9 are wet and bonded.

  In the heating device of the present invention, only the material having good X-ray permeability is used for the window portion 22 which is a range in which the sample is observed by X-ray, so that the solder wetting behavior is clearly observed under various temperature conditions. Can be observed.

  In addition, real-time observation can be performed under a preset temperature profile, which can be used for elucidating the void generation mechanism.

  Furthermore, since an external heat transfer mechanism is not required, the apparatus can be made smaller and thinner, so that the sample can be brought closer to the X-ray inspection apparatus, and extremely small parts can be clearly observed at a high magnification. It becomes possible.

  In addition, the object which uses the soldering apparatus which concerns on this invention is not limited to what was shown in FIG. 4, It can use also for the apparatus of the other structure described in patent documents 1-3, and also another apparatus.

  FIG. 5 shows a drawing-substituting photograph showing the external appearance of the example, and FIG. 6 shows a drawing-substituting photograph showing the exploded state.

  The shape and arrangement of the examples are slightly different from the embodiment shown in FIGS. 1 to 3, and the pipe 60 and the thermocouple 62 are arranged on the cover 44 side, but are included in the scope of the present invention.

  In addition, in the said embodiment and Example, although the planar shape of the container 40 was circular, other planar shapes, for example, a square, may be sufficient.

DESCRIPTION OF SYMBOLS 7 ... Board | substrate 8 ... Electronic component 9 ... Land 10 ... Solder paste 40 ... Container 42 ... Base 44 ... Cover 46 ... Bolt 48 ... Nut 50 ... Packing 60 ... Piping 62 ... Thermocouple

Claims (7)

A container that is excellent in X-ray transmission and has a base and a cover formed of a metal having high thermal conductivity, and can be opened and closed vertically.
A heat-resistant packing inserted into the gap between the base and the cover and having a function of preventing gas leakage;
An X-ray transmissive soldering apparatus, which itself has no heating source and is used with an apparatus having a heating source.   The X-ray transparent soldering apparatus according to claim 1, wherein the container is sealed by an atmospheric pressure applied to a fixture or the outside of the container.   3. The X-ray transmission according to claim 1, wherein a space for placing an object to be soldered is formed between the central portion of the cover and the base by swelling the central portion of the cover upward. Soldering equipment.   The upper surface of the base is flat, and the soldering target can be set in close contact with the inside of the base, and the thickness increases as it goes to the periphery. The X-ray transparent soldering apparatus according to claim 1, wherein the X-ray transparent soldering apparatus is provided.   The X-ray transparent soldering apparatus according to claim 1, wherein a pipe capable of making the inside of the container vacuum or high pressure is provided and connected to a vacuum pump or a compressor.   6. The X-ray transmissive soldering apparatus according to claim 1, wherein a thermocouple is inserted inside the container, and an external heating source is controlled at a temperature measured by the thermocouple.   The X-ray transparent soldering apparatus according to claim 1, wherein a magnesium alloy or an aluminum alloy is used as the metal having excellent X-ray transparency and high thermal conductivity.