JPH09181438A - Heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent warp of a board in heating by a method wherein carrying means carries substrates ranging over all passages of a preliminary heating step, a full heating step and a cooling step, while movement supporting means is forwarded synchronizing with the above speed by forwarding means, to perform heating. SOLUTION: A printed wiring board 6 is in a condition that it is supported by board carrying means 5 and a chain belt 11, and carried sequentially via a preheat part 2, a main heat part 3 and a cooling part 4. Until a heater is carried in from an inlet port 10A by the chain belt 11 provided ranging over all passages of a processing step of the printed wiring board 6 comprising the preheat part 2, the main heat part 3 and the cooling part 4 and is carried out from an outlet port 10B, the printed board 6 is supported from below at a plurality of locations, so that warp of the board can be prevented in heating.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD OF THE INVENTION Conventional Technology (FIGS. 6 and 7) Problems to be Solved by the Invention (FIGS. 8 and 9) Means for Solving the Problems Embodiments of the Invention (FIGS. 1 to 5) effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device, and is suitable for application to, for example, a reflow furnace used when soldering surface mount components to a printed wiring board.

[0003]

2. Description of the Related Art Conventionally, a reflow furnace has been used for surface mounting an electronic component on a printed wiring board having a desired wiring pattern formed on the front surface and / or the back surface by soldering. That is, solder is supplied to the printed wiring board in advance, terminals are placed at the solder supply positions to place electronic components, and the printed wiring board is heated to melt the solder and solder the terminals of the electronic components to the wiring pattern. It is designed to be attached.

In FIG. 6, reference numeral 1 denotes a heating device which is a reflow furnace as a whole. The heating device 1 is composed of a preheating unit 2, a main heating unit 3, a cooling unit 4 and a substrate carrying means 5. In the heating device 1, the printed wiring board 6 inserted in the direction of the arrow A shown in the drawing is transferred to the board transporting means 5.
The preheating unit 2, the main heating unit 3, and the cooling unit 4
Transport in order. Further, the heating device 1 first performs preliminary heating in the preheating unit 2, preliminary heating in the main heating unit 3, and subsequent cooling in the cooling unit 4 on the printed wiring board 6 to be conveyed. Further, as shown in FIG. 7 viewed from the direction of the arrow A in FIG. 6, the printed wiring board 6 on which the electronic components 7 are arranged on the front surface and the back surface prevents the preheating by the preheating unit 2 and the main heating by the main heating unit 3. In order to prevent it from being conveyed, only the both ends are brought into contact with the substrate conveying means 5 made of a chain belt for conveyance. Here, both ends of the printed wiring board 6 that come into contact with the board conveying means 5 are set in advance as component placement prohibited areas.

The printed wiring board 6 is formed by forming a desired wiring pattern using a conductor on an insulating plate such as a glass plate. Electronic component 7 arranged on printed wiring board 6
A cream-like solder is applied in advance between the terminals of the above and the surface of the printed wiring board 6. The printed wiring board 6 is put into the heating device 1 in such a state. The printed wiring board 6 placed in the heating device 1 is first preheated by the preheating unit 2. The preheat section 2 preliminarily preheats the printed wiring board 6 to dry the solvent contained in the solder, and also to apply an impact to the electronic component 7 arranged on the printed wiring board 6 by the rapid heating. I am trying not to let it go. The printed wiring board 6 is conveyed to the main heating section 3 after being preheated.

The main heating unit 3 heats the conveyed printed wiring board 6 at a high temperature to melt the solder applied to the printed wiring board 6, and the wiring pattern on the printed wiring board 6 and the terminals of the electronic component 7 are melted. Solder and.
After that, the printed wiring board 6 is conveyed to the cooling unit 4, and the molten solder is cooled and fixed to fix the connection between the wiring pattern and the terminal of the electronic component 7.
Thus, the heating device 1 heats the printed wiring board 6 to melt the solder applied on the board, thereby soldering each electronic component 7 to the wiring pattern formed on the surface of the printed wiring board 6. You can

[0007]

By the way, in the heating device 1 having such a configuration, the printed wiring board 6 is moved by the heat source (not shown) provided above or below the preheating section 2 and the main heating section 3. It is heated to melt the solder. However, since heating is performed only from one surface of the printed wiring board 6, the degree of thermal expansion differs between the directly heated surface of the printed wiring board 6 and the surface on the back side thereof, and the printed wiring board 6 itself There is a problem of being warped. That is, as shown in FIG. 8, the printed wiring board 6 causes a warp when the weight of the electronic component 7 arranged on the surface is in the vicinity of the center, so that the printed wiring board 6 is warped so as to bend downward. .

In order to avoid such a problem, a method may be considered in which a chain belt 8 is provided in the cooling section 4 and the printed wiring board 6 having a warp is pushed up from the lower surface to correct the warp. However, in this method, as shown in FIG.
The entire chain belt 8 comes into contact with the printed wiring board 6 within the area AR1, and when the electronic component 7 is arranged in the area AR1, the electronic component 7 may come into contact with the chain belt 8 and fall off. There is nature. For this reason,
The electronic component 7 cannot be placed in the area AR1, and as a result, the area AR1 must be a component placement prohibited area, which causes a problem of impeding high-density mounting. Further, when correcting the warp of the printed wiring board 6 that has been warped once, cracks or voids may occur due to the force applied to the solder joint portion.

The present invention has been made in consideration of the above points, and it is possible to prevent the warp of the substrate during heating without hindering the mounting of components on the substrate. Is to propose.

[0010]

In order to solve such a problem, according to the present invention, a carrier means for sequentially carrying a pre-heating step, a main heating step and a cooling step while supporting both ends of the substrate, and a narrow board on the substrate. A belt-shaped moving support means in which a plurality of connectors provided with projections for contacting with each other to support the substrate are connected, and a forwarding means for forwarding the moving support means are provided. Further, the detecting means for detecting the position of the protrusion and the pushing means for pushing the substrate onto the conveying means according to the detection result of the detecting means are provided.

The substrate is transported while abutting only the protrusion of the moving and supporting means against the substrate to support it. Further, the position of the protrusion is detected by the detecting means, and when the position of the protrusion reaches a predetermined position, the pushing means inserts the substrate into the heating device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 6 are designated by the same reference numerals, reference numeral 10 indicates a heating apparatus which is a reflow furnace as a whole. The heating device 10 is composed of a preheating unit 2, a main heating unit 3, a cooling unit 4 and a substrate carrying means 5, and the printed wiring board 6 loaded from the loading port 10A,
First, the preheating unit 2 performs preheating, the main heating unit 3 performs main heating, and the cooling unit 4 subsequently performs cooling.
In addition, the heating device 10 has a loading port 10A through a loading port 10A.
A chain belt 11 is provided which supports the printed wiring board 6 along all the paths up to and moves in synchronization with the movement of the board conveying means 5. Further, a sensor 13 for detecting a predetermined position of the chain belt 11 and a pusher 14 for pushing the printed wiring board 6 into the heating device 10 according to the detection result of the sensor 13 are provided. The heating device 10 is configured similarly to the heating device 1 except for these configurations.

As shown in FIG. 2, the chain belt 11 is formed by connecting a plurality of connectors 11A with connecting pins 12, respectively. A protrusion 11B is formed on one side of each connector 11A in a direction perpendicular to the longitudinal direction in which the connector 11A is continuous. The protruding portions 11B are intermittently provided on the chain belt 11 at predetermined intervals,
Each is a rectangular metal plate that protrudes from the chain belt 11 in one direction in the vertical direction by a predetermined length.

Further, as shown in FIGS. 3 and 4, the chain belt 11 is provided between the board conveying means 5 provided on the left and right for supporting the printed wiring board 6 at both ends. The chain belt 11 brings the protrusion 11B into contact with a plurality of positions at predetermined positions along the center line of the lower surface of the printed wiring board 6 so that the printed wiring board 6
I support. Then, with the lower surface of the printed wiring board 6 supported, the board conveying means 5 is sequentially fed in synchronization with the speed at which the printed wiring board 6 is conveyed. In this way, by synchronizing the forward movement of the chain belt 11 with the conveyance by the substrate conveying means 5, the protrusion 11B rubs the lower surface of the printed wiring board 6 to cause scratches or damage to mounted components. It is possible to prevent the protruding portion 11B from coming into contact and dropping the component.

Further, the sensor 13 (FIG. 1) detects whether or not the protruding portion 11B of the chain belt 11 has reached a predetermined position, and transmits the detection result to the pusher 14 (FIG. 1). The pusher 14 is provided in front of the input port 10A (FIG. 1), and pushes the printed wiring board 6 into the heating device 1 in accordance with the detection result given from the sensor 13 so that the board conveying means 5 and the chain belt 11 are connected. Put on. Here, the sensor 13 pushes the printed wiring board 6 into the heating device 1 by the pusher 14 for a certain period of time so that the printed wiring board 6 that is put in first and the printed wiring board 6 that is put next are not in contact with each other. It is set to start the next detection after the elapse. In this way, the heating device 10 detects the position of the protruding portion 11B and brings the protruding portion 11B into contact with the position where the electronic component 7 is not arranged, and mounts the printed wiring board 6 on the board conveying means 5 and the chain belt 11. It is done like this. Here, the printed wiring board 6 is transported with its both ends abutting against the substrate transport means 5 so as not to interfere with the preheating by the preheating unit 2 and the main heating by the main heating unit 3. For this reason, both end portions of the printed wiring board 6 that come into contact with the board conveying means 5 are set in advance as component placement prohibited areas.

The heating device 1 supports the lower surface of the printed wiring board 6 inserted through the inlet 10A at a predetermined position along the center line by the protrusions 11B, and at the same time, the printed board 6 by the board transfer means 5. Both ends of the sheet are supported and conveyed to the outlet 10B. The printed wiring board 6 conveyed is heated and melted by the pre-heating and main heating performed by the preheating unit 2 and the main heating unit 3 to melt the solder applied to the surface thereof, and further cooled by the cooling unit 4. As a result, the molten solder is fixed and the wiring pattern and the terminals of the electronic component 7 are soldered.

In the above structure, the printed wiring board 6
While being supported by the substrate transporting means 5 and the chain belt 11, they are sequentially transported through the preheating section 2, the main heating section 3 and the cooling section 4. The printed wiring board 6 preheated by the preheating unit 2 is conveyed to the main heating unit 3. The main heating by the main heating unit 3 melts the solder applied to the printed wiring board 6 to join the wiring on the printed wiring board 6 and the terminals of the electronic component 7. After that, the printed wiring board 6 is cooled by the cooling unit 4, and the molten solder is fixed. Thus, the printed wiring board 6 that has been connected by soldering is carried out of the heating device 10 through the carry-out port 10B.

The heating device 10 is provided with a chain belt 11 which is provided over the entire route of the process of treating the printed wiring board 6 including the preheating part 2, the main heating part 3 and the cooling part 4.
Thus, by supporting the printed wiring board 6 from the lower surface at a plurality of points until it is carried in from the carry-in port 10A and carried out from the carry-out port 10B, it is possible to prevent the printed circuit board 6 from being warped due to heating. it can. Further, as shown in FIG. 5, each connector 1 forming a chain belt 11
The chain belt is configured such that one side of the connector 1A is provided with a protrusion 11B provided in a direction perpendicular to the longitudinal direction in which the connector 11A is continuous so as to abut and support the printed wiring board 6 only in the area AR2. Compared to the case of supporting by 8 (FIG. 9), the contact area can be reduced.

Further, the printed wiring board 6 is provided with an input port 10.
The sensor 13 is placed in a standby state by pausing before A.
When it is detected that the protruding portion 11B of the chain belt 11 has reached a predetermined position, the pusher 13 pushes the protrusion 11B into the heating device 10 through the inlet 10A. By thus detecting the position of the protruding portion 11B and determining the closing timing, the protruding portion 11B can be always brought into contact with the same position of the printed wiring board 6 where the electronic component 7 is not arranged, It is possible to prevent the portion 11B from coming into contact with the electronic component 7 and dropping it.

According to the above construction, the printed circuit board 6 is supported from the lower surface by the chain belt 11 provided from the inlet 10A to the carry-out port 10B, so that the printed circuit board 6 is warped by heat. Can be prevented in advance. Further, protrusions 11B are intermittently provided at a predetermined interval on one side of each connector 11A forming the chain belt 11, and the protrusions 11B are provided in a narrow area AR.
Since the printed wiring board 6 is brought into contact with and supported by the printed wiring board 6 in FIG. 2, it is possible to widen the component placement area on the lower surface of the printed wiring board 6. Further, by detecting the position of the protrusion 11B by the sensor 13 and determining the closing timing, the protrusion 11B can be always brought into contact with the same position of the printed wiring board 6 where the electronic component 7 is not arranged. it can. Thus, it is possible to realize the heating device 10 capable of preventing warpage caused by heating the printed wiring board 6 in advance, without hindering high-density mounting.

In the above-described embodiments, the case where the present invention is applied to the reflow furnace used for soldering electronic parts to the printed wiring board 6 has been described, but the present invention is not limited to this and is generated by heating. If it is necessary to prevent warpage, it may be applied to other heating devices.

Further, in the above-mentioned embodiment, the case where the chain belt 11 for supporting the printed wiring board 6 is provided between the substrate carrying means 5 for carrying while supporting both ends of the printed wiring board 6 is described. However, the present invention is not limited to this, and the printed wiring board 6 may be supported by a plurality of chain belts. This makes it possible to increase the number of contact points between the protruding portion 11B and the printed wiring board 6, and to support the printed wiring board 6 more stably. At this time, if the protruding portion 11B is formed in a thin rod shape to reduce the contact area with the printed wiring board 6, it is possible to prevent the high-density mounting from being hindered by the increase in the contact portion.

Further, in the above-mentioned embodiment, the protrusions 11 for supporting the printed wiring board 6 are provided on the chain belt 11 formed by connecting the connectors 11A arranged on the left and right respectively with the connecting pins 12. Although the case has been described, the present invention is not limited to this, for example, to provide a protruding portion on a belt-shaped belt formed by connecting a plurality of one metal plate,
As long as it is a belt-shaped movement support means in which a plurality of connectors are connected, the movement support means may be provided in any shape to support the substrate.

Further, in the above-mentioned embodiment, the projection 11 for supporting the printed wiring board 6 is provided with the chain belt 11
Although the case where it is provided on one side of each connector 11A forming the above is described, the present invention is not limited to this, and each connector 11A.
The printed wiring board 6 may be supported by providing a protruding portion 11 between them.

[0026]

As described above, according to the present invention, the transport means for sequentially transporting the substrate to the preheating step, the main heating step and the cooling step while supporting both end portions of the substrate and the transport means in a narrow area on the substrate. By providing a belt-like movement supporting means in which a plurality of connectors provided with protrusions for contacting and supporting the substrate and forwarding means for feeding the movement supporting means are provided, only the protrusions of the movement supporting means are provided on the substrate. Since the substrate is transported while abutting and supporting it, the substrate can be transported while supporting it in a narrow area. Further, a detecting means for detecting the position of the protrusion and an extruding means for pushing the substrate onto the conveying means according to the detection result of the detecting means are provided, and the detecting means detects the position of the protruding portion to detect the position of the protrusion. Since the substrate is put into the heating device by the pushing means when the component comes to the predetermined position, the protrusion can be always brought into contact with the substrate at the same position where the component is not arranged. Thus, it is possible to realize a heating device capable of preventing the warp of the substrate during heating without hindering the mounting of components on the substrate.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a heating device according to an embodiment of the present invention.

FIG. 2 is a side view showing the structure of the chain belt according to the embodiment.

FIG. 3 is a front view for explaining the support of the substrate by the chain belt.

FIG. 4 is a side view provided for explaining the support of the substrate by the chain belt.

5A and 5B are a front view and a bottom view for explaining a contact area between a chain having a protrusion and a substrate.

FIG. 6 is a side view showing the configuration of a conventional heating device.

FIG. 7 is a front view provided for explaining a positional relationship between a substrate transfer unit and a substrate.

FIG. 8 is a front view for explaining a warp of the substrate due to heat.

9A and 9B are a front view and a bottom view used to explain a contact area between a normal chain and a substrate.

[Explanation of symbols]

1, 10 ... Heating device, 2 ... Preheating part, 3 ... Main heating part, 4 ... Cooling part, 5 ... Substrate transfer means, 6
...... Printed wiring board, 7 ... Electronic parts, 8,11 ...
Chain belt, 10A ... inlet, 10B ... outlet, 11A ... connector, 11B ... projection, 12 ... connecting pin, 13 ... sensor, 14 ... pusher.

Claims (4)

[Claims] 1. A heating device for heat-treating a substrate by preheating the substrate in a preheating process, heating the substrate in a main heating process, and cooling the heated substrate in a cooling process. And a conveying means for supporting both ends of the substrate to sequentially convey the substrate to the preheating step, the main heating step, and the cooling step, and a protrusion for abutting the substrate in a narrow region to support the substrate. It comprises a belt-shaped moving support means in which a plurality of connectors are connected, and a forwarding means for forwarding the moving support means, wherein the carrying means performs all of the preheating step, the main heating step and the cooling step of the substrate. The substrate is heat-treated while supporting the substrate by feeding the moving support means by the feeding means in synchronism with the speed of transport along the path. Heating device. 2. The heating device according to claim 1, wherein the moving support means is provided over the entire path of the preheating step, the main heating step, and the cooling step. 3. The heating device according to claim 1, wherein the moving support means is a chain belt, and the protrusion is provided only on one side of the pair of left and right connectors. 4. A detection means for detecting the position of the protrusion, and a pushing means for pushing the substrate onto the conveying means according to a detection result of the detection means. The heating device described.