JP3243124U - Reflow furnace - Google Patents

Abstract

A cooling mechanism for a reflow furnace capable of efficiently cooling after use and lowering the temperature during use when an electronic component is mounted on a wiring board using solder.
A reflow furnace used for mounting an electronic component on a wiring board using solder, wherein the reflow furnace is a base and is in contact with a mounting surface on which the wiring board is mounted and a heat source. It is composed of a base having a contact surface that absorbs heat, and a lid that is openable and closable on the mounting surface. A flow path is provided, and the base is pressed by an elastic body against the surface of the heat source on which the reflow furnace is mounted.
[Selection drawing] Fig. 7

Description

The present invention shortens the cooling time for returning the device to room temperature after completion of work, or the cooling time for lowering the temperature as necessary during use, in a reflow furnace used when mounting electronic components on a wiring board using solder. It relates to a cooling mechanism that can

Mounting boards on which electronic components are mounted are used in various products and contribute to the computerization of products. In general, a mounting board used when developing a product and mass-producing a completed device is a dedicated wiring board, and necessary electronic components are assembled by an automated board mounting apparatus. At that time, various devices have been proposed for applying cream solder to the mounting lands of the wiring board to solder the electronic component to the wiring board.

However, these board mounting apparatuses are large-scale for mass production, and are not suitable for mounting boards for trial production during product development. In addition, these days electronic components have become extremely fine, and skillful skill is required to manually solder them to the mounting lands of the wiring board using a soldering iron. The method of mounting an electronic component on the mounting land coated with the ten cream solder and reflowing the solder does not require much skill. A small-sized simple reflow oven has been proposed that allows researchers and engineers to easily fabricate prototypes and mounting substrates under development using cream solder on their work desks.

Patent Document 1 is a simple reflow furnace device filed in 2013 by the inventor of the present invention to solve the above problem. Since the melting of the solder can be observed through the window plate, the solder reflow of the mounting board can be easily performed. By providing the heat collection cover, preheating and main heating with good thermal efficiency can be performed.

Utility Model Registration No. 3229691

However, the device of Patent Document 1 can perform heating with good thermal efficiency by mounting a reflow furnace on the upper surface of the heat source of the existing heating device and providing a heat collecting cover in close contact with it, but when cooling after use or when necessary during use There was a drawback that it took a long time for cooling when the temperature was lowered. Since the heat trapped in the heat source and the reflow furnace cannot be efficiently radiated, the cooling takes a long time. This invention is a cooling mechanism for a reflow furnace that allows researchers and engineers to efficiently cool after use and lower the temperature during use when mounting electronic parts on a wiring board by soldering using an existing heating device. is to provide

In a reflow furnace used for mounting an electronic component on a wiring board using solder, the reflow furnace absorbs heat by being in contact with a mounting surface on which the wiring board is mounted, which is a base, and a heat source. a base having a close contact surface; and a cover that is openable and closable on the placement surface. The base is pressed by an elastic body against the surface of the heat source on which the reflow furnace is mounted.
Since the base is pressed by an elastic body and is in close contact with the heat source, it is possible to directly cool the base and the heat source by flowing a cooling medium through the flow path provided on the contact surface in spite of good heat conduction. It can dissipate the heat trapped in the device.

Furthermore, the heat collecting cover is composed of at least a top plate and a side plate, and the top plate includes an opening for allowing the reflow oven to pass therethrough. By arranging the reflow furnace in the opening of the heat collecting cover and mounting it on an existing heating device for heating, the temperature of the reflow space can be increased and preheated efficiently, and the cooling can be efficiently performed.

In the reflow furnace of the present invention, the flow path for compressed air, which is a cooling medium, is provided inside the base of the reflow furnace and on the contact surface, so that the reflow furnace main body and the heat source can be cooled at the same time. The cooling time can be shortened because the return cooling or the temperature lowering can be efficiently performed as needed during use.

Perspective view of the reflow furnace of the present invention Perspective view of the reflow oven with the lid body opened Front view of reflow furnace Rear view of reflow oven Perspective view with the heat collection cover attached Cross-sectional explanatory drawing including the heat collection cover Cross-sectional view explaining the cooling mechanism Bottom view of the reflow furnace (explanatory drawing of the contact surface)

The reflow furnace 1 of the present invention will be described with reference to the drawings. The reflow furnace 1 has a rectangular box shape, and the internal space thereof serves as a reflow space 70 for melting the solder applied to the land of the wiring board 101 . The reflow furnace 1 is composed of a base 20 on which a wiring board 101 on which electronic components 102 are mounted, and a lid 40 that is openable and closable on the top of the base 20. When the lid 40 is closed, The internal space formed by the cooperation of the base 20 and the lid body 40 serves as the reflow space 70 . When the reflow furnace 1 is heated by the heat source section 90 of the existing heating device, the temperature in the reflow space 70 reaches a temperature at which the solder melts, and the mounting board 100 is reflowed.

The base 20 has a rectangular outer shape and is formed of a metal plate, and faces the adhesion surface 21 to which heat is directly transferred from the heating means 90 when the reflow furnace 1 is mounted on an existing heating device. It has a mounting surface 23 on which the mounting substrate 100 to be reflowed is mounted and which conducts heat to the wiring substrate 101 which is the upper surface. The outer shape of the base 20 need not be rectangular, but may be circular, elliptical, polygonal, or any other shape. The material is preferably aluminum or copper, which have good thermal conductivity, but other metal materials may also be used.

Two recessed portions 25 are provided on each of the two side ends of the rectangular base 20 at intervals. The concave portion 25 is a countersunk surface having a depth from the mounting surface 23 to the middle in the thickness direction of the base 20 . Furthermore, the end face of the base 20 is provided with an inflow port 26 for compressed air, which is a cooling medium, and a flow path 27 leading to the inside from there and a flow path 28 open to the contact surface 21 are provided. The inflow port 26 and the flow paths 27 and 28 flow compressed air to release the heat trapped in the base 20 and the heat source section 90 to the outside of the device for cooling.

The lid body 40 is composed of a frame body 41 , a window plate 42 and a pressing plate 43 . The frame body 41 has a shape similar to that of the base 20 and has an opening 45 in the center, and is sized and shaped to surround the outer periphery of the mounting surface 23 of the base 20 . The window plate 42 is arranged in a groove 44 provided in the upper inner periphery of the frame 41 and fixed by a pressing plate 43 . A transparent heat-resistant glass material can be used for the window plate 42 so that the mounting substrate 100 mounted in the reflow space 70 can be observed. As with the frame 41 , the pressing plate 43 has an opening in the center and is fixed to the frame 41 with screws 49 to fix the window plate 42 in the recess 44 . However, without using the pressing plate 43, the window plate 42 may be directly fixed with screws or fixed to the frame 41 by other means.

The base 20 and the lid 40 are rotatably connected at their rear end portions by a hinge 50 . A shaft 51 extending in the X-axis direction with both ends fixed to two shaft holders 55 projecting from the left and right of the rear end of the base 20 is supported by two bearings 54 fixed to the rear end of the frame 41 . The base 20 and the lid body 40 are connected by being attached through the base 20 , so that the lid body 40 can rotate with respect to the base 20 . The spring 52 is a torsion coil spring and is attached so as to pass through the shaft 51 . One end of the spring 52 is hooked on the base 20 and the other end is hooked on the lid 40 . is urged to open. Two stoppers 56 are provided on the upper part of the shaft holder 55 , and the stoppers 56 restrict the rotation of the lid 40 by coming into contact with the rear end surface of the frame 41 . The height of the stopper 56 can be adjusted by a screw mechanism, and the opening angle can be adjusted by adjusting the height.

Also, the base 20 and the lid 40 are provided with hooks 60 at their front ends facing the hinges 50 . A receiving metal fitting 66 is fixed to the center of the front end face of the base 20, and the lever 61 provided on the lid body 40 enters the opening thereof, and the hanging metal fitting 63 is caught on the lower surface of the receiving metal fitting 66, whereby the lid body 40 is moved to the base. 20 is releasably fixed.
The lever 61 is rotatably supported between left and right bearings 65 fixed to the frame 41 by a support shaft 62 penetrating through the center of the lever 61 . By pulling the upper part of the lever 61 forward, the hook 63 is hooked to the lower surface of the receiving metal 66 to close the lid body 40. By pushing the upper part of the lever 61 backward, the locking metal 63 is released from the receiving metal 66 and the lid body is closed. A spring 52 of the hinge 50 rotates backward to open the door 40 .

The heat collection cover 80 is composed of at least a top plate 81 and a side plate 82 surrounding the periphery, and the top plate 81 is provided with an opening 83 into which the reflow furnace 1 is inserted.
In the opening 83, leaf springs 84, which are elastic bodies, are provided at positions corresponding to the four recesses 25 of the base 20. The tip of each leaf spring 84 is fitted into the corresponding recess 25 and exerts its elastic force. , the base 20 is pressed against the upper surface of the heat source section 90 and adheres thereto. The elastic body is not limited to a leaf spring, and may be a compression spring or the like.

The shape of the heat collecting cover 80 is similar to that of the reflow furnace 1 in FIG. The opening 83 has a shape conforming to the outer shape of the reflow furnace 1, and can be made larger than the outer shape of the reflow furnace 1 by about 10 mm. The height dimension of the opening 83 portion when the heat collecting cover 80 is attached to the heat source part 90 can be made larger than the height dimension of the mounting surface 23 of the reflow furnace 1 .
The heat collecting cover 80 can be made of a thin metal plate, and can be made of copper, aluminum, stainless steel, or the like, but may be made of a heat-resistant resin or the like.

The heat collection cover 80 and the reflow furnace 1 are placed and fixed on the upper surface of the heat source section 90 of the heating device in a state in which the reflow furnace 1 enters the opening 83 . The internal space formed by the upper surface plate 81, the side surface plate 82, and the upper surface of the heat source unit 90 is used as a heat collecting space 85, and the air heated in the heat source unit 90 rises along the side surface of the reflow furnace 1 toward the opening 83 (FIG. 6). refer.
The heat from the heat source part 90 is transferred to the contact surface 21 of the base 20, the mounting surface 23, and the reflow space 70. As shown in FIG. However, the conducted heat is always radiated from the upper surface and the outer peripheral portion of the reflow furnace 1 and slows down the temperature rise of the reflow space 70. Since the heated air flows in the heat space 85, the heat radiation is suppressed and the temperature in the reflow space 70 is maintained. Moreover, even when the lid 40 is opened when the mounting substrate 100 is carried in and out, heat dissipation can be minimized.

Compressed air, which is a cooling medium, is introduced from the inlet 26 when cooling the device after use or when lowering the temperature as necessary. The compressed air flows through the flow paths 27 and 28 and is ejected from the contact surface 23. The pressure of the compressed air slightly floats the entire reflow furnace 1, passes through the gap formed between the contact surface 21 and the heat source 90, and enters the heat collecting space 85. It diffuses out and flows out of the device through the opening 83 (see FIG. 7). As a result, the compressed air cools the base 20 and the central part of the heat source part 90, and the high temperature air trapped in the heat collecting space 85 is discharged to the outside, thereby cooling the entire reflow furnace. The cooling medium does not have to be compressed air, and nitrogen, helium, etc. can also be used.

In a general reflow furnace, a heat source and a plate on which a mounting board is mounted are brought into close contact with each other and fixed with an adhesive, screws, or the like in order to facilitate heat transfer from the heat source to the plate. Therefore, it takes more time to cool the reflow furnace after use, or to lower the temperature if necessary, than when raising the temperature.
In the reflow furnace cooling mechanism of the present invention, the base 20 of the reflow furnace 1 and the heat source part 90 are not fixed, but pressed by the leaf spring 84, which is an elastic body, to be brought into close contact with each other, and the cooling medium is applied to the contact surface 23 of the base 20. Compressed air can be jetted toward the central part of the heat source part 90 by the presence of the air flow path, and the air can be discharged to the outside through the outer peripheral part from the bottom of the reflow furnace, so that the entire device can be efficiently cooled in a short time. becomes easier.

The reflow furnace of the present invention can be mounted on an existing heating device and used by researchers and engineers in research laboratories, laboratories, etc., to mount electronic components on prototype wiring boards or the like using solder. . It can also be used for annealing treatment of metal materials and resin materials.

1 Reflow oven 20 Base 21 Close contact surface 23 Placement surface 25 Recess 26 Inlet 27 28 Channel 40 Lid 41 Frame 42 Window plate 43 Pressing plate 44 Groove 45 Opening 49 Screw 50 Hinge 51 Shaft 52 Spring 54 Bearing 55 Shaft Holder 56 Stopper 60 Hook 61 Lever 62 Support shaft 63 Hook 65 Bearing 66 Receiving metal 70 Reflow space 80 Heat collection cover 81 Top plate 82 Side plate 83 Opening 84 Leaf spring 85 Heat collection space 90 Heat source 100 Mounting substrate 101 Wiring Substrate 102 Electronic component

Claims (2)

In a reflow furnace used for mounting an electronic component on a wiring board using solder, the reflow furnace absorbs heat by being in contact with a mounting surface on which the wiring board is mounted, which is a base, and a heat source. a base having a close contact surface; and a cover that is openable and closable on the placement surface. and wherein the base is pressed by an elastic body against a surface of the heat source on which the reflow furnace is mounted. 2. The reflow furnace according to claim 1, further comprising a heat collection cover comprising at least a top plate and a side plate, the top plate having an opening through which the reflow furnace can pass.

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