JP2015204324A - Transportation heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device capable of making a jig unnecessary and surely preventing warpage of a printed board.SOLUTION: A transportation heating device comprises: a heating device for heating a body to be heated; at least two transportation conveyors which are parallelly provided in the heating device along the transportation direction; a clamp unit which is mounted on the transportation conveyor and has a presser piece capable of being opened and closed for holding at least the four corner adjacencies of the body to be heated; and the lower warp prevention body which is sent in synchronization with the transportation conveyor and supports a plurality of positions of the body to be heated during transportation from below.

Description

  The present invention relates to a conveyance heating apparatus that can be applied to, for example, a reflow apparatus that performs reflow of a printed circuit board.

  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 board is transported to a reflow furnace by a transport conveyor. The reflow apparatus includes a transport conveyor for transporting a substrate and a reflow furnace main body to which an object to be heated, such as a printed circuit board, 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.

  Each of the heating zones has an upper furnace body and a lower furnace body. For example, hot air is blown from the upper furnace body of the zone to the substrate, and hot air is blown from the lower furnace body to the substrate, so that the solder in the solder composition is melted and the printed circuit board electrodes and electronic components And are soldered. In the reflow apparatus, desired soldering is performed by controlling the temperature during heating according to a desired temperature profile.

In the mounting method using such a reflow apparatus, the thickness of the printed circuit board has recently been reduced with the downsizing and thinning of electronic devices, and the printed circuit board is likely to be warped. Furthermore, BGA (Ball Grid Array) is used as an electronic component mounted on a printed circuit board.
When using such a package, the difference in the amount of warpage due to the difference in thermal expansion during heating due to the difference between the thermal expansion coefficient of the BGA and the thermal expansion coefficient of the printed circuit board causes the package electrodes to peel off from the substrate. was there.

  Conventionally, in order to prevent mounting defects due to warping of the printed circuit board during heating, each jig is attached to an object to be heated. However, the use of the jig has a problem of reducing the workability of the mounting process because it requires labor for attaching and detaching the jig. As a method and apparatus not using a jig, the one described in Patent Document 1 has been proposed.

  In order to avoid the occurrence of heating unevenness on the printed circuit board, the heating device of Patent Document 1 is provided with a warpage prevention mechanism equipped on the lower surface portion of the central part of the printed circuit board, thereby causing heat absorption and heat shielding. A warp prevention mechanism is not provided.

JP 2007-001736 A

  In patent document 1, it is set as the structure equipped with two or more holding mechanisms which hold | maintain a part of edge part of a to-be-heated object at predetermined intervals. However, there is a problem that warping cannot be reliably prevented only by holding both ends of the object to be heated. Furthermore, in Patent Document 1, since it is necessary to wait for the work piece to be held in a state where the holding piece of the holding mechanism is rotated by 90 ° or more and to clamp the work, mechanical stress on the spring (using a spring hinge) is large. Moreover, since the thermal stress is applied, there is a problem that the spring is broken.

  Accordingly, an object of the present invention is to provide a heating device that eliminates the need for a jig and can reliably prevent warping of a printed circuit board.

In order to solve the above-described problem, the present invention includes a heating device for heating an object to be heated,
At least two conveyors for conveying the object to be heated, provided in parallel in the conveying direction in the heating device;
A clamp unit that is attached to a conveyor and has openable and closable pressing pieces that sandwich at least four corners of the object to be heated; and
It is the conveyance heating apparatus which consists of a downward warpage prevention body which is sent in synchronization with the conveyance conveyor and supports a plurality of locations of the heated object during conveyance from below.
Preferably, the pressing piece of the clamp unit is rotatably attached to the support shaft so as to be in an open position when the heated body is charged and in a holding position when the heated body is conveyed,
The support shaft is positioned below the conveying surface of the heated object.

  According to at least one embodiment, both end portions extending in the conveyance direction of the object to be heated are held by the plurality of clamp units, and the anti-warping body is disposed below the object to be heated. Can be prevented. Furthermore, in the present invention, the rotation angle of the pressing piece can be made smaller than 90 °, and the risk of the spring being broken can be reduced. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure. In addition, the contents of the present disclosure 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 basic diagram for demonstrating the curvature of the workpiece | work which generate | occur | produces in a reflow apparatus. It is a basic diagram which shows schematic structure of the reflow apparatus by one Embodiment of this invention. It is sectional drawing and an approximate line figure used for description of a lower curvature prevention body. It is a top view which shows an example of a structure of the state which conveys a workpiece | work. It is a top view which shows the other example of a structure of the state which conveys a workpiece | work. It is a basic diagram used for description of the contact position with respect to the workpiece | work of a downward curvature prevention body. It is a front view used for description of a clamp unit. It is a front view which shows the state of the clamp unit before throwing in a workpiece | work, and the state of the clamp unit after throwing in a workpiece | work. It is the side view and front view which are used for description of the opening / closing mechanism of a clamp unit. It is a basic diagram used for the front view and description of position shift of the holding | suppressing mechanism which reduces the position shift of the up-down direction of a conveyance conveyor. It is an approximate line figure used for explanation of one modification of a downward warpage prevention body. It is a basic diagram used for description of the other modification of a lower curvature prevention body. It is a basic diagram used for description of the modification of this invention. It is a basic diagram used for description of the modification of this invention.

Embodiments of the present invention will be described below. The description will be given in the following order.
<1. Conventional Reflow Device>
<2. Embodiment>
<3. Modification>
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 particularly limited to the present invention in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

<1. Conventional Reflow Device>
FIG. 1 shows a schematic configuration of a conventional reflow apparatus 101 to which the present invention can be applied. The reflow apparatus 101 includes a reflow furnace 102, and conveyance conveyors 103 and 104 that pass a substrate to be heated (for example, a work board) W on which surface-mounted electronic components are mounted on both sides, through the reflow furnace 102, Rotating bodies 105 a, 105 b, 105 c, 105 d that define the movement paths of the conveyors 103, 104 and an outer plate 106 are provided. In FIG. 1, only one conveyor 103 of two parallel conveyors is shown.

  The reflow furnace 102 is for heating the workpiece W from above and below and cooling it after heating. The transport conveyors 103 and 104 are two transport conveyors arranged in parallel with the transport direction. For example, roller chains are used as the conveyors 103 and 104. The outer plate 106 is a case for covering the whole.

  After the workpiece W is carried into the reflow furnace 102 from the carry-in entrance 107, it is carried at a predetermined speed by the conveyers 103 and 104 in the arrow direction (from left to right as viewed in FIG. 1), and finally the carry-out exit 108. Taken from. Although not shown, a work carry-in device for carrying the work W is provided in the front stage of the carry-in entrance 107, and a work carry-out apparatus for sending the work W to the outside is arranged in the rear stage of the carry-out port 108. .

  Along the transfer path from the carry-in port 107 to the carry-out port 108, the reflow furnace 102 is sequentially divided into, for example, nine zones Z1 to Z9, and these zones Z1 to Z9 are arranged in-line. Seven zones Z1 to Z7 from the carry-in port 107 side are heating zones, and two zones Z8 and Z9 on the carry-out port 108 side are cooling zones. A forced cooling unit (not shown) is provided in association with the cooling zones Z8 and Z9. The number of zones is an example, and other numbers of zones may be provided. The plurality of zones Z1 to Z9 controls the temperature of the workpiece W according to the temperature profile during reflow. Each of heating zones Z1-Z7 has an upper heating unit and a lower heating unit each including a blower.

  The first section is a temperature raising portion R1 where the temperature rises due to heating, the next section is a preheating (preheating) portion R2 with a substantially constant temperature, the next section is a reflow (reflow) portion R3, and the last section The section is the cooling unit R4. The temperature raising portion R1 is a period for heating the substrate 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 the oxide film on the surface of the electrodes and solder powder, and eliminating uneven heating of the workpiece. The reflow 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 reflow portion R3, the temperature needs to be raised to a temperature exceeding the melting temperature of the solder. The last cooling part R4 is a period in which the printed circuit board is rapidly cooled to form a solder composition. In the case of lead-free solder, the temperature in the reflow portion is higher (for example, 240 ° C. to 260 ° C.).

  In the reflow apparatus 101 having such a configuration, the zones Z1 and Z2 are mainly responsible for temperature control of the temperature raising portion R1. The zones Z3, Z4 and Z5 are mainly responsible for the temperature control of the preheating part R2. Zones Z6 and Z7 are responsible for temperature control of the reflow section R3. The zone Z8 and the zone Z9 are responsible for temperature control of the cooling unit R4.

  The warp of the workpiece W during the reflow of the reflow apparatus 101 described above will be described with reference to FIG. As shown in FIG. 2A, the workpiece W is obtained by mounting a chip component 112, a package component 113 such as a BGA, etc. on the A surface (front surface) of a substrate 111 on which a solder paste is printed. The soldering is completed through the heating and cooling steps by the reflow device 101. As shown in FIG. 2B, the substrate 111 is warped in the reflow process.

  The warp of the substrate 111 causes cracks and unmounting in the soldered portion of each electronic component, resulting in poor mounting. Furthermore, as shown in FIG. 2C, when printing the solder paste on the other side B, there is a problem that a printing failure in which the amount of the solder paste is uneven or a mounting failure of the package component 114 occurs. is there. The present invention prevents the occurrence of such mounting defects.

<2. Embodiment>
"Overall configuration of one embodiment"
As shown in FIG. 3, a reflow apparatus 1 according to an embodiment of the present invention carries a workpiece W from a carry-in entrance 3 into a reflow furnace 2 composed of an upper furnace body 2a and a lower furnace body 2b. The workpiece W is unloaded from the outlet 4. In the reflow furnace 2, similarly to the above-described conventional reflow apparatus 101, heating and cooling processes are performed, and electronic components mounted on the printed circuit board are soldered. Although not shown, a work carry-in device for supplying the work W is provided in the previous stage of the carry-in port 3, and a work carry-out device for sending the work W to the outside is arranged in the subsequent stage of the carry-out port 4. .

  The workpiece W is transported by the transport conveyor 5. The conveyor 5 is configured by, for example, a roller chain. A rotating body, for example, a sprocket 7a is arranged on the front side of the carry-in port 3, and a sprocket 7b is arranged on the rear side of the carry-out port 4, so that the workpiece W can be conveyed between the sprockets 7a and 7b. Further, the conveyor 5 is wound around the sprockets 7c, 7d, 7e, and 7f and has an endless configuration as a whole. For example, a rotational driving force is applied to the sprocket 7a, and the transfer conveyor 5 is transferred in the transfer direction.

  Further, a sprocket 8 a is arranged in the vicinity of the carry-in port 3, and a sprocket 8 b is arranged in the vicinity of the carry-out port 4. A roller chain 9 is bridged between the sprockets 8a and 8b. Further, the roller chain 9 is wound around a sprocket attached to a common shaft with the sprocket 7c and a sprocket attached to a common shaft with the sprocket 7f, so that the entire structure is endless. A conveyor 5 and a conveyor 6 are arranged in parallel to both sides of the conveyor path. The other conveyor 6 is also wound around each sprocket endlessly like the conveyor 5, and the conveyors 5 and 6 are sent synchronously. In FIG. 3, only one conveyor 5 of two parallel conveyors is shown. In order to avoid the thermal influence on the roller chain 9, a roller chain having a smaller heat capacity than that of the roller chains constituting the conveyors 5 and 6 is used. For example, a small roller chain 9 having a smaller pitch is used.

  A roller chain 10 is wound between a sprocket attached to a common shaft with the sprocket 8a and a sprocket attached to a common shaft with the sprocket 7a. For example, a rotational driving force applied to the sprocket 7 a by a driving device such as a motor (not shown) is transmitted to the shaft of the sprocket 8 a via the roller chain 10 to generate a force for sending the roller chain 9. Furthermore, the roller chain 9 is wound around the sprocket attached to the rotation shaft of the sprocket 7c of the conveyor 5 and the sprocket attached to the rotation shaft of the sprocket 7f. Therefore, the movement of the conveyor 5 and the movement of the roller chain 9 are synchronized. The conveyors 5 and 6 and the roller chain 9 are returned to the carry-in port 3 through the lower side of the reflow furnace 2 at the subsequent stage of the carry-out port 4.

"Anti-warping body"
The roller chain 9 is transported at a position lower (lower) than the height of the transport surfaces of the transport conveyors 5 and 6 between the sprockets 8a and 8b. A downward warping prevention body 11 that prevents the downward warping by supporting the lower surface side of the workpiece W protrudes upward from the roller chain 9. The lower warpage prevention body 11 is a metallic plate-like body or rod-like body attached to each link plate of the roller chain 9, for example. Since the lower surface of the workpiece W is supported by the lower warp prevention body 11, the workpiece W is prevented from being bent downward by the weight of the electronic component mounted during heating.

  As shown in FIG. 4A, the downward warping prevention body 11 contacts the workpiece W at a substantially central position in a direction orthogonal to the conveyance direction of the workpiece W to be conveyed. The roller chain 9 to which the lower warp prevention body 11 is attached is transferred. Furthermore, as shown in FIG. 4B, it is preferable that the lower warpage prevention body 11 contacts the workpiece W at a plurality of locations in the conveyance direction of the workpiece W. Since the feed of the workpiece W and the downward warpage prevention body 11 is synchronized, the downward warpage prevention body 11 can stably support the workpiece W.

  Although only one side is shown in FIG. 4A, as shown in FIGS. 5 and 6, two conveyors 5 and 6 are provided that extend in parallel with the conveyance direction of the workpiece W and are sent synchronously. ing. The conveyors 5 and 6 convey the workpiece W while sandwiching the left and right ends of the workpiece W individually. For example, each of the conveyors 5 and 6 is configured as a two-row integrated roller chain (so-called double roller chain). The conveyor 5 is constituted by roller chains 21a and 21b connected in parallel, and the conveyor 6 is constituted by roller chains 22a and 22b connected in parallel.

  Although omitted in FIGS. 5 and 6, as shown in FIGS. 4A and 9, guide rails 23 and 24 for guiding the outer roller chains 21b and 22b are provided. The guide rails 23 and 24 are provided in a region where the workpiece W is conveyed, and in this region, the roller chains 21a, 21b and 22a, 22b travel stably.

  A clamp unit 31 that clamps one end of the workpiece with respect to the inner roller chain 21a constituting the conveyor 5 is attached. Similarly, a clamp unit 32 that clamps one end of the workpiece with respect to the inner roller chain 22a constituting the conveyor 6 is attached. As shown in FIG. 5, the clamp units 31 and 32 are attached to the respective outer plates of the roller chains 21a and 22a. In this case, the clamp units 31 and 32 are attached to all pitches.

  As shown in FIG. 6, the clamp units 31 and 32 may be attached at a ratio of one of the two adjacent outer plates of each of the conveyors 5 and 6. The mounting interval between the clamp units 31 and 32 is selected so that the end portion of the workpiece W is in the range of length and the workpiece W is not warped. For this purpose, it is preferable that the clamp units 31 and 32 sandwich at least the vicinity of the four corners of the workpiece W.

  Since the lower warpage prevention body 11 supports the lower surface of the workpiece W, considering the case of a double-sided printed board, the workpiece W is supported at a location where no electronic component is mounted. Recently, in order to reduce costs, a plurality of circuit boards are produced from a single printed board. The example of FIGS. 5 and 6 is an example in which four circuit boards S1, S2, S3, and S4 are created from one printed board as shown in FIG. 7A. The four circuit boards S1 to S4 have the same board size, and are divided into four circuit boards after component mounting and soldering are completed, and unnecessary parts are cut off. In this case, the center position of the printed circuit board is a board division position and a position where no electronic component is mounted in a direction orthogonal to the transport direction. Therefore, in FIG. 7A, the downward warping prevention body 11 is brought into contact at a plurality of locations on the line indicated by the two-dot chain line.

  As shown in FIG. 7B, six circuit boards S1 to S6 may be created from one printed board. In this case, the position between the circuit boards S1, S2 and the circuit boards S3, S4 (indicated by a two-dot chain line) and the position between the circuit boards S3, S4 and the circuit boards S5, S6 (in a two-dot chain line) Is a board dividing position and a position where no electronic component is mounted. Therefore, in the example of FIG. 7B, the lower warp prevention body 11 is preferably brought into contact at a plurality of locations on the lines indicated by two-dot chain lines. For simplification, the anti-warping body may be in contact with only one of the positions indicated by the two-dot chain line. Further, as shown in FIG. 7C, when two circuit boards S1 and S2 are created from one printed board, electronic parts (package parts, chip parts, etc.) are not mounted on each circuit board. The lower warp prevention body 11 is brought into contact at a plurality of positions on the position (indicated by a two-dot chain line). Thus, it is desirable to set the position where the lower warpage preventing body 11 contacts according to the workpiece W, so the position in the direction perpendicular to the conveying direction of the lower warpage preventing body 11, that is, the roller chain 9 is adjusted. Possible (variable).

"Clamp mechanism"
The clamp units 31 and 32 will be described. Since these clamp units have the same configuration, the clamp unit 31 will be described as an example. FIG. 8 shows the clamp unit 31 in an enlarged manner. An L-shaped attachment plate 34 is formed integrally with the outer plate 33 of the inner roller chain 21 a constituting the transport conveyor 5. The support portion 35 is attached to the end portion of the attachment plate 34 with screws. Each part of the clamp unit 31 is made of a stainless steel material.

  A workpiece placement surface 36 is formed by forming a stepped portion inside the support portion 35 (on the conveyance path side of the workpiece W). An end portion of the workpiece W can be placed on the workpiece placement surface 36. A support shaft (pin) 37 that penetrates the support portion 35 in the transport direction is attached to the support portion 35. The shaft 37 is attached to the support portion 35 at a position below the workpiece placement surface 36.

  The pressing piece 38 is provided with a pressing plate on both side surfaces of the support portion 35 so that the leg portion is rotatably attached to the support shaft 37 and connects the ends of the leg portions. The lower end surface of the pressing plate comes into contact with the upper surface of the workpiece W, and the workpiece W is held between the end surface and the workpiece placement surface 36.

  Further, the presser spring 39 is disposed between the leg portion below the connecting position and the support portion 35 in a contracted state. The holding spring 39 is made of a stainless material, Inconel, or the like. The holding spring 39 generates a force that rotates the lower end of the leg portion in the direction of arrow P. That is, the work W is brought into a state where the front end surface of the presser piece 38 is bent by the presser spring 39 and is pressed against the work placement surface 36 by the front end surface. Thus, since the edge part of the workpiece | work W is clamped by the some clamp unit 31, generation | occurrence | production of the curvature of the workpiece | work W in a reflow process can be prevented.

  A protrusion 40 is formed on the rear side of the leg portion below the pressing piece 38. When the projection 40 is pushed inward against the spring force of the holding spring 39, the lower end of the leg is rotated in the direction of the arrow Q. The presser plate at the upper end of the presser piece 38 rotates rearward and rises, and transitions from a position where the work W is held (pressing position) to a non-holding position (open position). Furthermore, as indicated by a two-dot chain line, the upper end of the leg portion of the pressing piece 38 escapes beyond the width on both sides of the workpiece W, and the pressing piece 38 becomes an obstacle when the workpiece W is loaded at the start of the reflow process. Is prevented.

  FIG. 9A shows an open position immediately before the workpiece W is carried into the reflow apparatus. In this open position, the tip portions of the respective pressing pieces 38 of the clamp units 31 and 32 have escaped to the outside, so that the pressing pieces 38 are not obstructed when the workpiece W is loaded. 9B, the end portion of the work is sandwiched between the front end surface of each of the holding pieces 38 of the clamp units 31 and 32 and the work placement surface. Is done. The work W is securely held by the holding spring 39.

  Here, since the support shaft 37 is disposed below the workpiece placement surface 36, the rotation angle from the clamping position of the workpiece W to the open position when the workpiece is placed to place the workpiece W on the workpiece placement surface 36. Can be less than 90 °. As a result, the amount of expansion / contraction of the pressing spring 39 can be further reduced as compared with the case where the rotation angle is 90 °, the amount of expansion / contraction of the pressing spring 39 can be reduced, and the life thereof can be extended. .

  Before the carry-in port 3 of the reflow apparatus 1, the clamp units 31 and 32 are changed from the pressing position to the open position and the workpiece W is loaded, and then the clamp units 31 and 32 are changed to the pressing position and the workpiece W is moved. A sandwiching operation is performed. The operation of (pressing position → opening position → pressing position) is performed by the cam plate 41 as shown in FIG. FIG. 10 shows the configuration of the clamp unit 31 and the cam plate 41. Although not described, cam plates are also provided for the other clamp units 32 in the same relationship as the relationship between the clamp unit 31 and the cam plate 41. The cam plate 41 is made of a resin (PEEK, Teflon (registered trademark), etc.) excellent in heat resistance and sliding resistance.

  The cam plate 41 is fixed coaxially with the rotating support shaft 42. The sprockets 43a and 43b are fixed in parallel to the support shaft 42. The roller chains 21a and 21b are fed by meshing with the sprockets 43a and 43b and rotating the roller chains 21a and 21b. For example, the sprockets 43a and 43b correspond to the sprocket 7a in the reflow device 1 of FIG.

  The cam plate 41 is positioned between the clamp unit 31 (in FIG. 10, reference numerals 31a to 31e are assigned to the respective clamp units) and the outer plate 33 of the roller chain 21a. To be made. Further, the projection 40 of the clamp unit 31 is in contact with the outer surface of the cam plate 41 to slide along an arcuate locus. On the cam plate 41, a slope 45 is formed in the vicinity of the position where the clamp unit 31 starts to contact, and a slope 46 is formed in the vicinity of the position where the contact of the clamp unit 31 ends.

  The slope 45 is formed so that the thickness of the cam plate 41 gradually increases from the inlet into which the clamp unit 31 enters toward the outlet. The clamp unit 31a in FIG. 10A is controlled by the slope 45 so that the pressing piece 38 rises from the pressing position to the vicinity of the opening position. The clamp unit 31b is in a state where the pressing piece 38 is raised to the open position. The clamp units 31c and 31d are also in the open position. For example, the workpiece W thrown into the clamp unit 31d is placed.

  The slope 46 is formed so that the thickness of the cam plate 41 gradually decreases from the entrance into which the clamp unit 31 enters to the exit. The holding piece 38 of the clamp unit 31e that has entered the slope 46 changes from the open position to a slightly depressed position. After passing through the slope 46, the pressing piece 38 of the clamp unit 31 is closed to the pressing position, and the workpiece W is clamped. It passes through the reflow furnace in this state. By the slope 46, the clamp unit 31 is bent down with a gradual change from the open position to the holding position. Therefore, it is possible to prevent the workpiece W from being vibrated when the workpiece W is clamped, and to prevent the position of the electronic component from being shifted due to the vibration.

  Although not shown, a cam plate is provided in association with the sprocket 7b on the outlet side of the carry-out port 4 shown in FIG. The cam plate on the outlet side sequentially changes the clamp unit 31 from (pressing position → opening position → pressing position). The workpiece after the reflow is completed can be discharged by changing from the pressing position to the opening position. Also at this time, since the operation of the clamp unit 31 gradually changes, it is possible to prevent the workpiece W from being vibrated. Similarly, the other clamp unit 32 is provided with a cam plate on the outlet side, and the clamp unit 32 operates similarly to the clamp unit 31. Furthermore, in the section where the clamp units 31 and 32 are returned from the outlet side to the inlet side below the reflow furnace, the pressing piece 38 is closed and the work piece is closed compared to the open position. It is possible to avoid contamination of the surface in contact with W. Further, the work W can be reliably held by the clamp units 31 and 32 without adjusting the input timing of the work W with respect to the reflow apparatus 1, and control of timing adjustment and the like can be unnecessary.

"Pressing mechanism"
In one embodiment, the clamp unit is attached to the roller chain inside the double roller chain constituting the conveyor. Therefore, when the piece of the roller chain moves while being tilted, the workpiece may be warped. In order to avoid this problem, in one embodiment, a pressing mechanism is provided.

  As shown in FIG. 11A, the roller portion of the roller chain 21a to which the clamp unit 31 is attached is supported and transferred by a plate-like lower rail 51. A holding plate 52 that elastically holds the roller portion of the roller chain 21a from above is provided. The holding plate 52 is rotatably attached to the support shaft 53 and is provided so as to extend downward from the tip of a support arm 55 that is elastically supported by a spring 54 that is a tension spring.

  In addition, you may arrange | position the press board 52 so that there may be a slight clearance with respect to the roller part of the roller chain 21a, without providing the spring 54. FIG. Furthermore, the place which suppresses the roller chain 21a is not restricted to a roller, A plate may be sufficient. A similar pressing mechanism is provided for the other clamp units 32.

  11D and 11E schematically show the conveyance state of the roller chain 21a. In the example of FIG. 11D and FIG. 11E, the clamp unit 31 is intermittently provided on the outer plate 33 of the roller chain 21a. As shown in FIG. 11D, when no inclination occurs in each frame of the roller chain 21a, the workpiece W does not warp. However, as shown in FIG. 11E, the frame may be inclined due to the structure of the roller chain 21a and the clearance with the guide. As a result, when the work W is viewed from the side, it becomes a wave-like shape.

  Since the pressing plate 52 elastically presses the roller chain 21a downward by the pressing mechanism shown in FIG. 11A, each frame of the roller chain 21a is kept horizontal, and the conveyance level in the vertical direction can be optimized. The holding mechanism may be provided in all sections of the reflow furnace 2, but may be provided only in a section where warpage is likely to occur (for example, an area around the glass transition temperature of the workpiece W from the reflow heating zone to the cooling zone). . As shown in FIG. 11B, a configuration in which the pressing mechanism presses the roller chain 21a from the upper side and the lower rail 51 directly presses the support portion of the clamp unit 31 is also possible. Furthermore, as shown in FIG. 11C, a configuration in which the pressing mechanism directly presses the clamp unit 31 from the upper side is also possible.

<3. Modification>
`` Modifications of anti-warping body ''
The above-described lower warp prevention body 11 is a metallic plate-like body or rod-like body attached to each link plate of the roller chain 9. However, other configurations are possible for the downward warping prevention body. As shown in FIGS. 12A and 12B, a wire 81 having a diameter of about 1.5 mm is brought into contact with the lower surface of the workpiece W on a line where no electronic component is mounted. The wire 81 is sent in synchronization with the roller chains 21a and 21b that constitute the transport conveyor 5. 12A is a view seen from the entrance side of the transport path, and FIG. 12B is a view seen from the side of the transport path. As shown in FIG. 12A, the wire 81 is wound around the pulley 82.

  As shown in FIGS. 13A and 13B, the net conveyor 83 may be used as a downward warping prevention body. FIG. 13A is a view seen from the entrance side of the transport path, and FIG. 13B is a view seen from the side of the transport path. In FIG. 13A, illustration of a roller around which the net conveyor 63 is wound is omitted. Since the net conveyor 63 is in surface contact with the workpiece W, it is preferable that the workpiece W has no electronic component mounted on the lower surface thereof. In addition, when the work W is a thin substrate (for example, a flexible substrate), it is also preferable to use the net conveyor 63.

“Modification of transport path”
In the above-described embodiment, a pair of transport conveyors 5 and 6 form one transport path. As shown in FIG. 14, the present invention can also be applied to a reflow apparatus that forms a plurality of, for example, two transport paths. In addition, in FIG. 14, illustration of the lower curvature prevention body is abbreviate | omitted for simplicity.

  The first transport path 61 is constituted by roller chains 63a and 63b guided by guide rails 62a and 62b, respectively. As the roller chain in FIG. 14, a single roller chain is used. A clamp unit 64 is attached to the roller chain 63a, and a clamp unit 65 is attached to the roller chain 63b. These clamp units 64 and 65 are the same as the clamp units 31 and 32 in the embodiment. The workpiece W1 is clamped by the clamp units 64 and 65.

  The second transport path 71 is constituted by roller chains 73a and 73b guided by guide rails 72a and 72b, respectively. A clamp unit 74 is attached to the roller chain 73a, and a clamp unit 75 is attached to the roller chain 73b. These clamp units 74 and 75 are the same as the clamp units 31 and 32 in the embodiment. The workpiece W2 is clamped by the clamp units 74 and 75.

  As shown in FIG. 14B, the positions of the roller chain 63b inside the first conveyance path 61 and the roller chain 73b inside the second conveyance path 71 can be changed. Therefore, the width of each conveyance path is configured to be changeable, and it is possible to cope with soldering of the workpieces W11 and W12 having different widths. Furthermore, two conveyance paths can be provided, and a workpiece can be placed on each conveyance path for soldering, so that the efficiency of soldering can be improved.

  Shields 67 and 77 are provided between these two transport paths 61 and 71. The shields 67 and 77 are configured as plate-like bodies having a substantially L-shaped cross section. The shields 67 and 77 are fixed so as to stand substantially vertically from the upper and lower surfaces of the guide rails 62b and 72b at positions where the two conveyance paths are adjacent to each other. The shields 67 and 77 are provided to suppress temperature interference between the adjacent conveyance paths 61 and 71. As the shields 67 and 77, a stainless (SUS) plate, an aluminum plate, a plate coated with a far-infrared radiation paint, or the like can be used.

  The present invention can also be applied to a reflow apparatus in which two transport paths as described above are provided in parallel, as in the embodiment. In addition, as a conveyance conveyor with a variable position, not only the roller chains 62b and 63b and the roller chains 72b and 73b mentioned above but another roller chain may be used. Further, three or more conveyance paths may be provided.

  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, the present invention is not limited to a printed circuit board, but can also be applied to a flexible substrate, a substrate obtained by bonding a rigid substrate and a flexible substrate, and a reflow of a rigid flexible substrate obtained by combining these substrates. Furthermore, the present invention can be applied not only to the reflow device but also to a heating device for curing the resin. The configurations, methods, steps, shapes, materials, numerical values, and the like given in the above-described embodiments are merely examples, and different configurations, methods, steps, shapes, materials, numerical values, and the like 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. Furthermore, as shown in FIG. 15, the structure which does not provide a downward curvature prevention body is also possible.

W ... Work 1 ... Reflow device 2 ... Reflow furnace 5, 6 ... Conveyors 9, 10, 21a, 21b, 22a, 22b ... Roller chain 11 ... Lower warp prevention body 31 32 ... Clamp unit 35 ... Support portion 36 ... Work placement surface 37 ... Support shaft 38 ... Presser piece 39 ... Presser spring 40 ... Protrusion 41 ... Cam plate 52 ... Presser plate 54 ... Spring

Claims (8)

A heating device for heating an object to be heated;
At least two transport conveyors that are provided in parallel in the transport direction in the heating device and transport the heated object;
A clamp unit that is attached to the transport conveyor and has an openable and closable pressing piece that sandwiches at least four corners of the heated object; and
A conveyance heating apparatus comprising a downward warpage prevention body that is sent in synchronization with the conveyance conveyor and supports a plurality of locations of the heated object during conveyance from below.   The conveyance heating apparatus according to claim 1, wherein the pressing piece of the clamp unit is configured to gently close the pressing piece when transitioning from the open position to the pressing position. The clamp piece of the clamp unit is rotatably attached to a support shaft so as to be in the open position when the heated body is charged and to be in the pressed position when the heated body is transported,
The transport heating apparatus according to claim 2, wherein the support shaft is positioned below the transport surface of the heated body. After the object to be heated is carried out from the carry-out port of the heating device, an endless transfer path is formed in which the conveyor conveys the lower side of the heating device in the reverse direction and returns to the carry-in side,
When the clamp unit carries out the object to be heated, the holding position is set to the open position,
The conveyance heating apparatus according to claim 3, wherein the heated body is returned to the pressing position after being carried out.   The position in the direction orthogonal to the conveyance direction of the said to-be-heated body is variable so that the said downward curvature prevention body may be supported from the downward direction on the 1 or several line in which the components of the to-be-heated body are not arrange | positioned. The conveyance heating apparatus in any one of Claims 1 thru | or 4.   The conveyance heating apparatus according to any one of claims 1 to 5, further comprising a pressing mechanism that optimizes a conveyance level in a vertical direction of the conveyance conveyor.   The said heating mechanism is a conveyance heating apparatus of Claim 6 which suppresses the said conveyance conveyor with elasticity from an upper direction. In the heating device, provided in parallel along the transport direction, and having at least two transport conveyors for transporting the heated object,
The conveyance heating apparatus according to claim 1, wherein at least one position of the two conveyance conveyors is displaced so as to vary a width orthogonal to the conveyance direction.

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