JP2018073902A - Reflow device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heating temperature difference occurring due to difference in thermal capacity.SOLUTION: A reflow device includes a blower, a first heater placed in a gas flow path formed by the blower, a heating panel having multiple small holes, and blowing hot wind formed by the first heater to a heated object through the small hole, and a second heater attached to the heating panel via a shield plate, so as to be parallel with and/or orthogonal to the transport direction of the heated object, and heating the heated object with radiation heat. The second heater is turned ON/OFF independently in relation to the thermal capacity of an electronic component mounted on the heated object.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a reflow apparatus, and in particular, prevents soldering failure due to a difference in heat capacity between electronic components.

  A reflow apparatus is used in which a solder composition is supplied in advance to an electronic component or a printed circuit board, and the printed circuit board is conveyed in a reflow furnace by a conveyor. The reflow apparatus includes a transport conveyor for transporting an object to be heated and a reflow furnace main body to which the object to be heated is supplied by the transport conveyor. For example, the reflow furnace is divided into a plurality of zones along a transfer path from a carry-in port to a carry-out port, and the plurality of zones are arranged in-line. The plurality of zones have roles such as a heating zone and a cooling zone depending on their functions.

  In the heating zone, soldering is performed by blowing hot air against the printed circuit board. The heat capacities of a plurality of electronic components mounted on the same printed circuit board are not constant. Large parts such as QFP (Quad Flat Package) and BGA (Ball Grid Array) have a large heat capacity, and small parts such as an aluminum electrolytic capacitor have a small heat capacity. When these electronic components are mixed and mounted, a difference occurs between the temperature rise of the electronic component having a small heat capacity and the temperature rise of the electronic component having a large heat capacity in the reflow process. When the temperature of the hot air is adjusted to an electronic component having a small heat capacity, heating of the electronic component having a large heat capacity becomes insufficient, which may cause a soldering failure. Conversely, when the temperature of hot air is adjusted to an electronic component having a large heat capacity, the electronic component having a small heat capacity may be damaged.

  A reflow apparatus that reduces such a temperature difference is described in Patent Document 1. In Patent Document 1, by blowing hot air from a plurality of pipe nozzles onto a circuit board, a plurality of hot air blowing points are dispersed on the circuit board plane, and after the blown hot air bounces off the circuit board, the arranged pipes Hot air is circulated in the furnace through a flow path formed by the space between the nozzles. Furthermore, it is described that a radiant heat heater is provided between pipe nozzles in order to increase the amount of heat supplied to a large component.

Japanese Patent No. 4043694

  The reflow apparatus described in Patent Document 1 increases the amount of heat supplied to a large electronic component by using a radiant heater, but the radiant heater has a support plate that supports not only the electronic component to be heated but also the pipe nozzle. As a result, the region heated by the support plate is enlarged, and there is a problem in terms of performing local heating.

  Accordingly, an object of the present invention is to provide a reflow device capable of enhancing the heating capability for an electronic component having a large heat capacity even when electronic components having different heat capacities are mixed and mounted on an object to be heated. There is to do.

  The present invention includes a blower, a first heater disposed in a gas flow path formed by the blower, and a plurality of small holes, and hot air formed by the first heater is heated through the small holes. And a second heater that is attached to the heating panel via a shielding plate so as to be parallel and / or orthogonal to the conveying direction of the object to be heated and heats the object to be heated with radiant heat. A reflow device in which the second heater is independently turned on / off in association with the heat capacity of the electronic component mounted on the object to be heated.

  According to at least one embodiment, since an electronic component having a large heat capacity is additionally heated by the radiant heat of the second heater, the occurrence of problems due to the difference in the heat capacity of the object to be heated can be reduced. Moreover, since it can prevent that the heat | fever of a 2nd heater diffuses into a heating panel via a shielding board, local heating can be performed favorably. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure. Further, the contents of the present invention are not construed as being limited by the exemplified effects in the following description.

It is a basic diagram which shows the outline of the conventional reflow apparatus which can apply this invention. It is a graph which shows the example of the temperature profile at the time of reflow. It is sectional drawing which shows an example of a structure of one heating zone of a reflow apparatus. It is sectional drawing which shows an example of a structure of one heating zone of a reflow apparatus. It is sectional drawing which shows the cross section of the reflow apparatus used for description of one embodiment of this invention. It is sectional drawing which shows the cross section of the reflow apparatus used for description of one embodiment of this invention. It is the one part front view and top view of one Embodiment of this invention. It is a partial enlarged view of one embodiment of the present invention. It is a partial enlarged view of one embodiment of the present invention. It is a partial enlarged view used for description of the modification of the arrangement method of the heater of one embodiment of this invention. It is a basic diagram which shows an example of the temperature profile of this invention.

Embodiments of the present invention will be described below. The description will be given in the following order.
<1. Example of reflow equipment>
<2. Embodiment>
<3. Modification>
Note that the embodiment described below is a preferred specific example of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is specifically described in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

<1. Example of reflow equipment>
FIG. 1 shows a schematic configuration of a conventional reflow apparatus to which the present invention can be applied. In FIG. 1, illustration of the flux collection | recovery apparatus arrange | positioned outside a reflow furnace for convenience of explanation is abbreviate | omitted. An object to be heated, on which electronic components for surface mounting are mounted on both sides of the printed circuit board, is placed on a conveyor, and is carried into the furnace body of the reflow apparatus from the carry-in entrance 11. The conveyor conveys the object to be heated in the direction of the arrow (from left to right as viewed in FIG. 1) at a predetermined speed, and the object to be heated is taken out from the carry-out port 12. The transport direction of the transport conveyor is the horizontal direction.

  A reflow furnace is sequentially divided into, for example, nine zones Z1 to Z9 along the conveyance path from the carry-in port 11 to the carry-out port 12, and these zones Z1 to Z9 are arranged in-line. Seven zones Z1 to Z7 from the inlet side are heating zones, and two zones Z8 and Z9 on the outlet side are cooling zones. A forced cooling unit 14 is provided in relation to the cooling zones Z8 and Z9.

  The plurality of zones Z1 to Z9 described above controls the temperature of the object to be heated according to the temperature profile during reflow. FIG. 2 shows an outline of an example of the temperature profile. The horizontal axis represents time, and the vertical axis represents the surface temperature of a printed circuit board on which an object to be heated, such as an electronic component, is mounted. The temperature of the hot air for heating is higher. The first section is the temperature raising portion R1 where the temperature rises due to heating, the next section is the preheating (preheating) portion R2 where the temperature is substantially constant, the next section is the main heating portion R3, and the last section is This is the cooling unit R4.

  The temperature raising portion R1 is a period in which the substrate is heated from room temperature to a preheating portion R2 (for example, 150 ° C. to 170 ° C.). The preheating portion R2 is a period for performing isothermal heating, activating the flux, removing oxide films on the surfaces of the electrodes and solder powder, and eliminating uneven heating of the printed circuit board. The main heating portion R3 (for example, 220 ° C. to 240 ° C. at the peak temperature) is a period in which the solder is melted and the joining is completed. In the main heating part R3, the temperature needs to be raised to a temperature exceeding the melting temperature of the solder. Even when the preheating portion R2 has passed, the main heating portion R3 needs to be heated to a temperature exceeding the melting temperature of the solder because there is uneven temperature rise. The last cooling section R4 is a period in which the printed circuit board is rapidly cooled to form a solder composition.

  In FIG. 2, curve 1 shows the temperature profile of lead-free solder. The temperature profile in the case of Sn—Pb eutectic solder is shown by curve 2. Since the melting point of lead-free solder is higher than the melting point of eutectic solder, the set temperature in the preheating portion R2 is higher than that of eutectic solder. Further, the temperature of the hot air is set to a temperature higher than the surface temperature of the printed circuit board. For example, the temperature of the hot air is set to 300 ° C to 350 ° C.

  In the reflow apparatus, the heating zones Z1 and Z2 are mainly responsible for temperature control of the temperature raising portion R1 in FIG. The temperature control of the preheating part R2 is mainly handled by the heating zones Z3, Z4 and Z5. The heating zones Z6 and Z7 are responsible for temperature control of the main heating unit R3. The cooling zone Z8 and the zone Z9 are responsible for temperature control of the cooling unit R4.

  Each of the heating zones Z1 to Z7 has an upper furnace body 15 and a lower furnace body 35 each including a blower. For example, hot air is blown against the article to be heated W conveyed from the upper furnace body 15 and the lower furnace body 35 in the zone Z1.

  An example of the heating zone (heating device) will be described with reference to FIG. For example, a cross section when cutting any one of the heating zones Z1 to Z7 along a plane parallel to the transport direction is shown in FIG. 3, and a cross section when cut along a plane orthogonal to the transport direction is shown in FIG. It is shown. Within the gap between the upper furnace body 15 and the lower furnace body 35, an object to be heated (also referred to as a workpiece) W on which one or both surfaces of the printed circuit board are mounted is mounted on the conveyor 41. Placed and transported. The upper furnace body 15 and the lower furnace body 35 are filled with, for example, nitrogen (N2) gas, which is an atmospheric gas. The upper furnace body 15 and the lower furnace body 35 heat the article to be heated W by blowing hot air (heated atmospheric gas) onto the article to be heated W. In addition, you may irradiate infrared rays with a hot air.

  The upper furnace body 15 includes, for example, a blower 16 (comprising a motor and rotary blades) configured as a turbofan, and a rectifying mechanism provided to disperse the wind from the blower 16 to make the temperature distribution in the furnace body uniform. 17 and a heater 18 configured by bending a plurality of heater wires. The rectifying mechanism 17 is configured by a punching plate in which a large number of small holes are formed at equal intervals.

  Furthermore, a large number of small holes, for example, injection nozzles 19 through which hot air formed by the heater 18 passes, have a heating panel 21 protruding from the flat support plate 20 with respect to the object W to be heated. Hot air that has passed through the spray nozzle 19 is blown against the article W to be heated from above. The support plate 20 and the injection nozzle 19 of the heating panel 21 are integrally formed by a casting method including a die casting method using aluminum, zinc or magnesium as a material, or a drawing method.

  A recovery plate 22 is arranged in parallel with the support plate 20 of the heating panel 21 via a predetermined gap. The collection plate 22 has a hole or a slit for collecting the return gas of hot air blown to the article W to be heated by the heating panel 21.

  The heated hot air blown from the injection nozzle 19 and recovered by the recovery plate 22 passes through the gap between the support plate 20 of the heating panel 21 and the recovery plate 22, and further passes through the recovery passage to pass through the central portion of the blower 16. It is sucked in from the suction mouth and blows out downward. The blown gas is heated by the heater 18.

  The lower furnace body 35 has the same configuration as the upper furnace body 15 described above. That is, for example, a blower 26 having a turbofan configuration, a rectifying mechanism 27 disposed oppositely to disperse the air from the blower 26 and make the temperature distribution in the furnace uniform, and a plurality of heater wires are folded back. And a heater 28 configured as described above.

  In addition, a large number of small holes, for example, injection nozzles 29 through which hot air formed by the heater 28 passes, are provided with a heating panel 31 protruding from the flat support plate 30 with respect to the object to be heated W. Hot air that has passed through the spray nozzle 29 of the heating panel 31 is blown against the article W to be heated from below. A plurality of injection nozzles 29 are formed on the support plate 30 in a grid pattern or a five grid pattern.

  A recovery plate 32 is arranged in parallel with the support plate 30 of the heating panel 31 via a predetermined gap. The collection plate 32 has a hole or a slit for collecting the return gas of hot air blown to the article W to be heated by the heating panel 31.

  The heated hot air blown from the injection nozzle 29 and recovered by the recovery plate 32 passes through the gap between the support plate 30 and the recovery plate 32 of the heating panel 31 and further passes through the recovery passageway to the central portion of the blower 26. It is sucked from the suction port and blown upward. The blown gas is heated by the heater 28.

  Unlike the heating zones, the cooling zones Z8 and Z9 are configured not to have the heaters 18 and 28, and the cooling gas (inert gas such as N2 gas or the atmosphere) is passed through the cooling panel by the blowers provided above and below. Thus, it is configured to be sprayed onto the object to be heated W. The cooling panel is formed by forming a large number of small holes in a metal plate such as aluminum.

  In such a reflow apparatus, in the case of an object to be heated W in which an electronic component having a large heat capacity such as a BGA and an electronic component having a small heat capacity such as an aluminum electrolytic capacitor are mounted and mixed, a reflow process (a preheating process and a book) There is a risk that good soldering may not be performed in the heating step) or electronic components may be damaged. The present invention minimizes the temperature difference that occurs during the reflow process.

<2. Embodiment>
An embodiment of the present invention will be described with reference to FIGS. In one embodiment, the present invention is applied to a reflow apparatus as shown in FIGS. Therefore, in FIG. 5 and FIG. 6, the same reference numerals are given to the portions corresponding to FIG. 3 and FIG.

  The gas formed by the blower 16 is blown downward from the periphery and blown to the heating panel 21 via the rectifying mechanism 17. It is sprayed against the object to be heated W through the spray nozzle 19 of the heating panel 21. A heater 18 as a first heater is provided in the gas flow path, and the gas is heated by the heater 18 to form hot air.

  As shown in FIGS. 7A and 7B, a heater Ha serving as a second heater is provided on the surface of the recovery plate 22 disposed in parallel with the heating panel 21 and facing the object to be heated W via a shielding plate 23. It is done. 7A is a cross-sectional view taken along a plane orthogonal to the conveyance direction of the article to be heated W as in FIG. 6, and FIG. 7B is a plan view of the heating panel 21, the heater Ha, and the recovery plate 23 as viewed from below. is there. However, in FIG. 7A and FIG. 7B, illustration of the slit formed in the collection | recovery board 22 is abbreviate | omitted for simplicity. Moreover, the conveyance direction of the heating object W is shown by the arrow in FIG. 7B.

  The heater Ha has a rod shape, for example, a cylindrical shape, and a plurality of heaters Ha are arranged so that the extending direction thereof is parallel to the conveyance direction of the article to be heated W. The heater Ha performs radiant (radiant) heating. For example, as shown in an enlarged view in FIG. 8, the object to be heated W is heated by irradiating infrared rays (or far infrared rays). FIG. 8 partially shows the spray nozzle 19, the heater Ha, and the shielding plate 23. As the heater Ha, various heaters such as a sheathed heater, a ceramic heater, a quartz tube heater, etc. adapted to radiate infrared rays can be used.

  The shielding plate 23 is a reflecting plate formed by bending a metal having high reflectance such as aluminum, and has a circular arc shape along the tube surface of the heater Ha or a trapezoidal cross section with an open bottom. Since the infrared ray generated in the heater Ha and directed toward the recovery plate 22 is reflected downward by the shielding plate 23, the infrared ray is also diffused to the recovery plate 22 through the shielding plate 23 while being heated by the reflection component. Can be prevented. This can prevent the effect of local heating from decreasing. Further, a temperature detection sensor 24 such as a thermocouple is attached to at least one surface of the heater Ha in order to detect the temperature of the heater Ha. The temperature detection sensor may be provided in contact with the recovery plate 22.

  In the above-described embodiment, as illustrated in FIG. 9, the heater Ha and the shielding plate 23 are disposed so as to extend in a direction parallel to the conveyance direction of the article to be heated W. A slit G (or hole) for collecting the return gas of hot air blown to the article to be heated W is formed in the collection plates 22 and 32. The slit G forms a path for collecting the return gas reflected from the heated object W. That is, the hot air after heating the object to be heated that has passed through the slit G passes through the gap between the support plate 20 and the recovery plate 22 of the heating panel 21, passes through the recovery passage, and is sucked from the suction port at the center of the blower 16. , Blown down. The blown gas is heated by the heater 18. A heater Ha is provided so as not to block the slit G.

  FIG. 10 is an enlarged plan view for explaining a modified example of the arrangement of the heaters Ha, and the conveyance direction of the article to be heated W is indicated by an arrow. As shown in FIG. 10A, the heater Ha may be provided so as to be orthogonal to the conveyance direction of the article W to be heated. Furthermore, as shown in FIG. 10B, a heater Ha1 disposed in a direction parallel to the transport direction and a heater Ha2 disposed in a direction orthogonal to the transport direction may be provided.

  Similar to the heater Ha of the upper furnace body 15 described above, the lower furnace body 35 is also provided with a heater Hb as a second heater. That is, a heater Hb as a second heater is provided via the shielding plate 33 on the surface of the recovery plate 32 arranged in parallel with the heating panel 31 so as to face the object to be heated W. The heater Hb has a rod shape, for example, a columnar shape like the heater Ha, and a plurality of heaters Hb are arranged so that the extending direction thereof is parallel to the conveying direction of the article to be heated W. The heater Hb performs radiation (radiation) heating. Note that the heaters Ha and Hb may be divided into a plurality of longitudinal directions, and the divided portions may be independently turned on / off.

  The shielding plate 33 is a reflecting plate formed by bending a metal having high reflectance such as aluminum, and has a circular arc shape along the tube surface of the heater Hb or a trapezoidal cross section with an open bottom. Since the infrared rays generated in the heater Hb and directed toward the collection plate 32 are reflected upward by the shielding plate 33, it is possible to prevent the infrared rays from being diffused to the collection plate 32 through the shielding plate 33. This can prevent the effect of local heating from decreasing. Further, a temperature detection sensor such as a thermocouple is attached to at least one surface of the heater Hb in order to detect the temperature of the heater Hb. The temperature detection sensor may be provided in contact with the collection plate 32. Similar to the heater Ha, the heater Hb can be arranged as shown in FIG.

  Each of the heaters Ha and Hb can be independently turned on / off in association with the heat capacity of the electronic component mounted on the article to be heated W. In this case, the heaters Ha and Hb are turned on so as to increase the temperature of the hot air for the electronic component having a large heat capacity. Information such as the size of the object to be heated W to be reflowed, the components to be heated, and the arrangement thereof is prepared in advance based on, for example, the Gerber data of the substrate, and based on the information, For example, the control unit of the reflow apparatus controls ON / OFF of the heaters Ha and Hb. For example, ON / OFF control of the heaters Ha and Hb is performed such that only the heaters near the line of the object to be heated W on which the BGA, which is a high heat capacity component, is arranged are set to a predetermined temperature and turned on.

  For example, as shown in an enlarged view in FIG. 11, both the electronic parts (BGA and the like) P1 and P2 having a large heat capacity and the electronic parts (aluminum electrolytic capacitors and the like) Q1 and Q2 having a small heat capacity are mounted. If there is, the heater Ha immediately above the electronic components P1 and P2 is selectively turned on. As a result, as shown in the temperature profile of the thin line, the heating temperature for the electronic components P1 and P2 is, for example, 230 ° C. because the partial heating of the heater Ha is applied in addition to the hot air (for example, a temperature of 200 ° C.). . On the other hand, the heating of the electronic components Q1 and Q2 is performed by hot air at 200 ° C. without partial heating because the heater Ha is OFF. Since the heat capacities of the electronic parts P1 and P2 are large, the surface temperature of the electronic parts P1 and P2 and the surface temperature of the electronic parts Q1 and Q2 become substantially equal as a result of increasing the heating temperature in this way. The difference can be reduced. Although omitted in FIG. 11, the heater Hb is also controlled in the same manner as the heater Ha.

  Since the article to be heated W is transported by the transport conveyor 41, it is not stationary. Therefore, the heaters Ha and Hb are turned on / off so that the heating temperature is appropriate for each of the electronic components of the article to be heated W being conveyed. However, it is also possible to perform the heat treatment in a state where the conveyance speed of the article to be heated W is changed or the conveyance of the article to be heated W is stopped.

<2. Modification>
Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments, and various modifications based on the technical idea of the present disclosure are possible. For example, one heater Ha and Hb may be arranged for each of a plurality of spray nozzles. Furthermore, it is good also as a structure which has only one of an upper side furnace body and a lower side furnace body. Furthermore, the second heater may be provided in all of the plurality of heating zones, or the second heater may be provided in a part of the heating zones. Further, the configurations, methods, processes, shapes, materials, numerical values, and the like given in the above-described embodiments are merely examples, and different configurations, methods, processes, shapes, materials, numerical values, etc. are used as necessary. May be. The configurations, methods, steps, shapes, materials, numerical values, and the like of the above-described embodiments can be combined with each other without departing from the gist of the present disclosure.

DESCRIPTION OF SYMBOLS 11 ... Carry-in port 12 ... Carry-out port 14 ... Forced cooling unit 15 ... Upper furnace body 16, 26 ... Blower 18, 28 ... First heater 19, 29 ... Injection Nozzles 20, 30 ... support plate 22, 32 ... recovery plate 23, 33 ... shielding plate 35 ... lower furnace body 41 ... transport conveyor Ha, Hb ... second heater

Claims (8)

A blower,
A first heater disposed in a gas flow path formed by the blower;
A heating panel that has a plurality of small holes and blows hot air formed by the first heater onto the object to be heated through the small holes;
A second heater that is attached to the heating panel via a shielding plate so as to be parallel and / or orthogonal to the conveyance direction of the heated object, and that heats the heated object with radiant heat,
A reflow apparatus in which the second heater is independently turned on / off in association with the heat capacity of an electronic component mounted on an object to be heated.   The said shielding board is interposed between the said 2nd heater and the said heating panel, and is a reflecting plate which reflects the infrared rays or far infrared rays which the said 2nd heater generate | occur | produces in the said to-be-heated material side. Reflow equipment.   The reflow apparatus according to claim 1 or 2, wherein the second heater is turned on so as to increase a heating temperature for an electronic component having a large heat capacity.   The reflow apparatus according to any one of claims 1 to 3, wherein the heating panel includes a flat support plate and a plurality of injection nozzles that protrude from the support plate with respect to an object to be heated. A recovery plate is provided that has a hole or a slit that is arranged substantially in parallel with the support plate through a gap, and that allows the return of hot air blown to the object to be heated by the heating panel.
The reflow apparatus according to any one of claims 1 to 4, wherein the second heater is attached to the recovery plate.   The reflow apparatus according to claim 1, wherein a temperature detection sensor is provided in the second heater.   The reflow apparatus according to any one of claims 1 to 6, wherein a temperature detection sensor is provided on the heating panel.   The reflow device according to any one of claims 1 to 7, wherein the second heater has a rod shape.

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