JPH088527A - Infrared heating device - Google Patents

Abstract

PURPOSE:To surely join a joint of a work by local heating carried out in a short time without causing a thermal strain or the like to the work by a method wherein the work is preliminarily heated so as to form a gentle thermal gradient around its joint by preliminary heating. CONSTITUTION:When works W are intermittently transferred by a conveyer 5 and stopped at preliminary heating stations P1 and P2, they are irradiated with infrared rays emitted from preliminary heating light guiding pieces 8, 8..., the joint of the work W is preliminarily heated to rise in temperature while the conveyer 5 is stopped. When the work W is stopped at a processing station S after it is preliminarily heated, it is heated as irradiated with infrared rays which are emitted from a main heating light guiding piece 6 and high enough in energy density to heat its joint up to a prescribed joining temperature while the conveyer 5 stops and subjected to a soldering process. By this setup, the work W is gradually raised in temperature at preliminary heating stations P1 and P2 and furthermore slowly heated up to a prescribed joining temperature, so that the work is protected against thermal strain caused by quick heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies infrared rays to a joining portion of a work to which a soldering process, a brazing process, an assembly process of a thermoplastic resin component, a thermosetting resin heat-curing, a hot-melt adhesive, etc. are applied. The present invention relates to an infrared heating device that irradiates a laser beam to heat the bonding site to a required bonding temperature.

[0002]

2. Description of the Related Art For example, when automatically soldering a terminal of an electronic component to a land portion of a printed circuit board, conventionally, by irradiating infrared rays to a joint portion, only the joint portion is locally contacted without contact. It is known to heat.
The heating by infrared rays has an advantage that the irradiation part can be locally heated, but those having good thermal conductivity such as metal and those reflecting light well have a slow temperature rise,
There is a problem that it takes time to reach the melting temperature of the solder.

In order to simply raise the temperature of the bonding portion in a short time, the energy density of the infrared rays to be irradiated may be increased. In this case, however, the substrate is thermally distorted or warped due to a rapid temperature rise, or the substrate is heated. Are burned or solder balls are formed, resulting in product defects. For this reason, conventionally, the work is put in an electric heating furnace, the whole is irradiated with an infrared lamp, or hot air is blown, so that the temperature of the solder does not melt the whole work (80 to 12).
Preheating is performed to about 0 ° C.) to prevent the harmful effects caused by rapid heating of the joint portion, and vaporize the excess solvent of the flux to increase the affinity with the solder.

[0004]

However, since the main work is performed after preheating the entire work, a plurality of steps are required to heat one joining portion and the processing time is longer. In addition to the above, there is a problem that heating the entire work causes damage to the heat-sensitive electronic components, resulting in defective products. Therefore, it is a technical object of the present invention to perform local heating in a short processing time with a very simple structure and without causing thermal strain so that reliable bonding can be achieved.

[0005]

In order to solve this problem, the first invention of the present application is to attach a carrier of a conveyor to stop a work to be conveyed at a predetermined position, and to apply infrared rays to a joint portion of the work. In the infrared heating device for irradiating, the conveyor is an intermittent conveyor that intermittently conveys the work attached to the carrier at a uniform pitch by a predetermined pitch corresponding to the attachment pitch, and is conveyed by the intermittent conveyor and is predetermined. The main heating light guide that radiates infrared rays to the joining part of the preceding work that arrived at the position to heat the joining part to the required joining temperature, and the preceding stage position of the preceding work heated by the light guide It is characterized in that a preheating light guide body for irradiating infrared rays to a joint portion of a succeeding work to preheat and heat the joint portion is arranged.

The second invention of the present application is an infrared heating device for irradiating infrared rays to a joint portion of a work placed at a predetermined position, and irradiating infrared rays having a high energy density to the substantially center of the joint portion. A main heating light guide that heats a point to a predetermined bonding temperature or higher, and a peripheral heating that irradiates the peripheral portion of the irradiation point with infrared rays having a low energy density to heat the peripheral portion to a temperature lower than the bonding temperature. A light guide is provided.

[0007]

According to the first aspect of the present invention, while the preceding work conveyed by the intermittent conveyor is heated to the required joining temperature by the infrared rays emitted from the main heating light guide, the succeeding work is preliminarily prepared. Infrared rays emitted from the heating light guide are lower than the joining temperature (for example, about 80 to 12 in the case of soldering).
It is preheated to 0 ° C. That is, the work is first preheated and then is finally heated, and is not heated rapidly until the joining temperature is reached. Since the gradient is formed, there is no thermal strain even when heated to the bonding temperature.

Further, when the work is heated by the main heating light guide, since the joining portion of the work is already preheated by the preheating light guide, the work can be heated to the joining temperature in a short time. Therefore, the down time of the conveyor that intermittently conveys the work is shortened and the production efficiency is improved. Furthermore, since the preheating is sequentially performed at the stage of intermittently conveying the work, it is not necessary to variably control the light amount.

Further, according to the second aspect of the present invention, since infrared rays having a high energy density are irradiated to substantially the center of the joint portion and infrared rays having a low energy density are irradiated to the peripheral portion of the irradiation point, The temperature distribution at the joint is high at the center and gradually decreases toward the periphery, so that the thermal strain is relaxed. Further, since the joint area is heated to some extent around the irradiation point of the infrared ray having a high energy density, the heat of the infrared rays radiated to the approximate center is less likely to be dissipated from the joint section, and the heating time can be shortened.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on the embodiments shown in the drawings. FIG. 1 is an explanatory view showing an infrared heating device according to the present invention, and FIG. 2 is a graph showing a temperature change of a joining portion of a work.

In FIG. 1, reference numeral 1 denotes an infrared heating device for soldering the terminals 4 of the electronic component 3 to the land of the printed circuit board 2, and the workpieces W, W, ... The work W mounted on the carrier of the conveyor 5 at an equal pitch is intermittently conveyed by a predetermined pitch corresponding to the mounting pitch and stopped at the processing position S where the soldering process is performed, and the work W stopped at the processing position. It is designed to irradiate the joint area with infrared rays.

At the processing position S of the work W, the joining portion of the arrived work W is irradiated with infrared rays to heat the joining portion to a required joining temperature (in the case of soldering, above the melting temperature of the solder). A main heating light guide 6 is provided. Further, the infrared rays emitted from the main heating light guide 6 are selected to have an energy density such that the workpiece W that has arrived can be heated to the joining temperature within the stop time of the conveyor 5.

Further, infrared rays are radiated to the joining portion of the succeeding work W which has arrived at the preheating positions P ₁ and P ₂ which are the pre-stage positions of the processing position S where the preceding work W is heated by the main heating light guide 6. Pre-heating light guides 8, 8 for preheating the joint portion by preheating are provided. Infrared rays emitted from the preheating light guides 8, 8 ... Can not heat the joint portion to a required joint temperature (melting temperature of solder in the case of soldering) within the stop time of the conveyor 5. Has been selected for the energy density. That is, pre-heating positions P ₁ and P ₂ for pre-heating the joining portion of the work W by the pre-heating light guide are formed on the upstream side of the processing position S,
Until the work W reaches the processing position S, the preheating positions P ₁ , P
Each time it is stopped at ₂ , it is preheated by the preheating light guides 8, 8.

The main heating light guide 6 and the preheating light guides 8, 8 are formed of a bundle fiber in which a large number of optical fibers are bundled, and are connected to the same light source 7 and The heating light guide body 6 has a larger number of optical fibers than the sub-heating light guide bodies 8 and 8 and can irradiate infrared rays having a high energy density. A condenser lens 9 for condensing infrared rays is provided at the tip of each light guide 6, 8, 8.

The above is an example of the configuration of the present invention, and its operation will be described below. First, the work W is the conveyor 5
.. are intermittently conveyed at each of the preheating positions P ₁ and P ₂ , and infrared rays are emitted from the preheating light guides 8, 8 ... Is heated, and the joint portion of the work W is preheated.

FIG. 2 is a graph showing the temperature change at the joining portion. The work W that has arrived at the preheating position P ₁ is approximately equal to room temperature, and the work 5 is stopped while the conveyor 5 is stopped at the preheating position P _1. The workpiece W is heated from room temperature to the temperature T ₁ by irradiating infrared rays on the joint portion of W, and then the workpiece W is
Is stopped at the preheating position P ₂ , the infrared rays are irradiated again, and the work W is heated to the temperature T ₂ . When the preheating is completed and stopped at the processing position S, the conveyor 5
Infrared with an energy density that can heat the joint portion to a predetermined joint temperature within the stop time is irradiated from the main heating light guide 6 to perform main heating, and the joint temperature at which the joint portion of the work W melts the solder. The temperature is raised to Th or higher, and the soldering process is performed.

As described above, the infrared rays having a very high energy density are not irradiated at the processing position S, but the temperature is gradually raised at the preheating positions P ₁ and P ₂ , and the bonding temperature is reached for a long time. Since it is heated, thermal distortion or the like due to rapid heating does not occur. Further, the predecessor work W can be preheated and the main work can be preheated at the same time as the predecessor work W is preheated. Since the joining portion of the work W that has reached the processing position S is already heated to a certain temperature, It takes a very short time to heat this to the joining temperature, and therefore, the stop time of the conveyor 5 can be shortened and the production efficiency can be improved. Further, since the infrared rays are collected and applied only to the bonding portion, the entire printed circuit board is not heated and the electronic parts which are easily damaged by heat are not damaged. Furthermore, since preheating is sequentially performed at the stage where the work W is intermittently conveyed by the conveyor 5, it is also necessary to variably control the energy density of infrared rays emitted from the light guides 6, 8 and 8. In addition, preheating can be performed with a simple configuration.

FIG. 3 (a) is a perspective view showing another example of the preheating light guide body 8. In this example, the preheating light guide body 8 is arranged at the preheating positions P ₁ and P _2. It is not provided separately for each, but is formed so as to irradiate infrared rays in a strip shape along the transport direction of the work W. However, in this case, when the conveyor 5 is stopped, it is heated up to a place on the printed circuit board that does not need to be heated. Therefore, the energy density of the infrared rays emitted from the preheating light guide 8 is controlled. Must be set low.

FIG. 3B is a side view showing another example, in which one light system (lens system) 10 is irradiated with a plurality of lights from each light guide 6, 8, 8. Infrared rays are applied to the joint portions of the workpiece W stopped at the preheating positions P ₁ and P ₂ and the processing position S, respectively. As the work W passes through the preheating positions P ₁ and P ₂ and the processing position S, the cumulative irradiation time of infrared rays becomes longer, so the energy density of the infrared rays irradiated from the preheating light guide 8 is It can be arbitrarily set as long as the joining site does not reach the joining temperature before the work W reaches the processing position S, and the energy density of infrared rays emitted from the main heating light guide 6 is higher than the energy density. Good.

Further, in the embodiment, the case where the infrared heating device 1 is used as the soldering device has been described, but the present invention is not limited to this, and for example, brazing, assembly of thermoplastic resin parts, heat treatment Needless to say, it can be used as a local heating device for heat-curing a curable resin and for bonding with a hot-melt adhesive. Then, for example, when it is necessary to maintain a certain temperature when heating and adhering the thermosetting resin or the hot melt adhesive, as shown in FIG. The post-heating light guide 11 is provided on the main heating guide 6, and after the heating by the main heating light guide 6 is completed, infrared rays are radiated to the joint part of the work W conveyed to the rear side by the conveyor 5 so that the joint part has a predetermined temperature or lower. You may make it maintain so that it does not go down. The number of times of the preheating and the postheating described above can be arbitrarily set according to the type of the work W, the joining temperature, and the like.

FIG. 4 is an explanatory view showing another infrared heating device according to the present invention. In this example, the energy density from the main heating light guide 12 and the peripheral heating light guide 13 to the work W is changed. By irradiating different infrared rays at the same time, a temperature gradient is formed to prevent thermal distortion. Specifically, the main heating light guide 12 that irradiates infrared rays having an energy density capable of heating the joint portion of the work W to a predetermined joint temperature or higher toward the substantially center of the joint portion, and the periphery of the irradiation point 14. The portion 15 is provided with a peripheral edge heating light guide 13 that irradiates a ring-shaped infrared ray having an energy density lower than that of the infrared ray emitted from the main heating light guide element 12.

In this example, the light guides 12 and 13 are
Are each formed of a bundle fiber in which a large number of optical fibers are bundled, and are connected to the same light source 16.
The main heating light guide 12 is provided with a condenser lens 17 at its tip so that infrared rays can be focused and a pinpoint spot light can be emitted toward the approximate center of the joint. There is.

When the work W is placed at the processing position, infrared rays having a high energy density are irradiated from the main heating light guide 12 to substantially the center of the joining portion, and at the same time, the peripheral edge of the irradiation point is heated. Infrared rays having a low energy density are emitted from the light guide body 13 for use. As shown in FIG. 5, in the joining portion, only the substantially center is heated to the joining temperature, and the peripheral portion is heated to a predetermined temperature lower than the joining temperature, and a temperature gradient in which the temperature decreases from the center to the outside is formed. Formed,
Thermal strain is relieved. Further, since the peripheral portion is heated to a certain temperature, the heat of the infrared rays radiated to the center is less likely to be dissipated from the peripheral portion of the joining portion, and the heating time is shortened.

FIG. 6 is a plan view showing another arrangement example of the main heating light guide 12 and the peripheral heating light guide 13.
In this example, the tip of the bundle fiber that becomes the light guide 13 for heating the peripheral edge is branched into a plurality of pieces, which are arranged at predetermined intervals on the circumference with the light guide 12 for main heating as the center. Further, the projected image of infrared rays emitted from the light guide 13 for heating the peripheral edge is not limited to a circular shape, and can be arbitrarily changed according to the shape of the joint portion.

Further, the optical fiber used in the present invention and the optical system used for the light guides 6, 8, 12, 13 and the optical system such as lenses 9, 10, 17 absorb infrared rays and generate heat. A material having a high infrared transmittance which is difficult to be converted and a material having a high heat resistance are selected, and for example, a quartz fiber, a glass fiber, a quartz lens, a glass lens, a sapphire lens and the like are suitable. Furthermore, the light source used in the present invention is not limited to a case where a single light source is used for preheating and main heating and is branched by a bundle fiber or the like, and separate light sources may be used. It is more economical to use one light source.

[0026]

As described above, according to the first aspect of the present invention, the joint portion of the succeeding work can be preheated while the joint portion of the preceding work is main-heated.
Even if the conveyor stop time is shortened and the conveyor speed is increased, it is possible to increase the temperature rise time of each work piece without causing thermal distortion, and it is possible to improve the production efficiency. Have. Also, unlike the case of preheating with an electric heating furnace, an infrared lamp, or hot air, by heating the whole, there is no damage to electronic components that are susceptible to heat damage, and only local heating is required, so that energy can be saved. There is also. Furthermore, if the preheating position is irradiated with infrared rays of the required energy density, preheating is performed sequentially only by intermittently transporting the work, so there is no complicated mechanism for variably controlling the infrared energy density. There is also an effect that it becomes unnecessary and the cost of the equipment can be reduced by making the structure extremely simple.

Further, according to the second aspect of the present invention, since the peripheral portion of the joint portion of the work is heated to a temperature not reaching the joint temperature, it is possible to form a temperature gradient between the center and the peripheral portion. In addition, since the heat applied to the central part is less likely to be diffused to the surroundings, even if the heat is applied in a short time, thermal distortion is unlikely to occur, and the production efficiency can be improved, which is a very excellent effect.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an infrared heating device according to the present invention.

FIG. 2 is a graph showing a temperature change of a joint portion of a work.

FIG. 3 is an explanatory view showing another embodiment.

FIG. 4 is an explanatory view showing another infrared heating device according to the present invention.

FIG. 5 is a graph showing a temperature distribution of a joint portion of a work.

FIG. 6 is a plan view showing another embodiment.

[Explanation of symbols]

1-Infrared heating device W-Work S-Processing position P ₁ , P _2- Preliminary heating position 5-Conveyor 6-・ ・ Main heating light guide 7 ・ ・ ・ ・ ・ Light source 8 ・ ・ ・ ・ ・ ・ Preheating light guide 11 ・ ・ ・ ・ Post heating light guide 12 ・ ・ ・ ・ ・ Main Light guide for heating 13 ・ ・ ・ Light guide for rim heating 14 ・ ・ ・ ・ ・ ・ Irradiation point 15 ・ ・ ・ ・ ・ ・ Rim edge 16 ・ ・ ・ Light source

Claims (6)

[Claims] 1. In an infrared heating device, wherein a work (W) attached to a carrier of a conveyer (5) and conveyed is stopped at a predetermined position, and infrared rays are irradiated to a joint portion of the work, wherein the conveyer (5) is , An intermittent conveyer that intermittently conveys a work (W) attached to a carrier at a uniform pitch by a predetermined pitch corresponding to the attachment pitch, and is conveyed by the intermittent conveyer at a predetermined position (S)
Of the main heating light guide (6) for irradiating infrared rays to the joining portion of the preceding work that has arrived at and heating the joining portion to a required joining temperature, and the preceding work heated by the light guiding body (6). An infrared heating device, comprising: a preheating light guide (8) for irradiating infrared rays to a joining portion of a succeeding workpiece that has arrived at a front stage position to preheat and raise the joining portion. 2. After the heating by the main heating light guide (6) is completed, infrared rays are radiated to the joint portion of the work (W) conveyed to the rear stage side by the intermittent conveyor so that the joint portion has a predetermined temperature or lower. The infrared heating device according to claim 1, further comprising a post-heating light guide body (10) arranged so as not to lower. 3. The infrared heating device according to claim 1, wherein the main heating light guide (6) and the preheating light guide (8) are connected to the same light source (7). 4. The light guide (6) for main heating, the light guide (8) for preheating and the light guide for post-heating are connected to the same light source (7). Infrared heating device described. 5. An infrared heating device for irradiating infrared rays to a joint portion of a workpiece placed at a predetermined position, irradiating infrared rays having a high energy density to a substantially center of the joint portion to make a predetermined irradiation point (14). The main heating light guide (12) that is heated to the bonding temperature or higher and the peripheral edge (15) of the irradiation point (14) are irradiated with infrared rays having a low energy density, and the peripheral edge (1).
An infrared heating device, characterized in that a peripheral edge heating light guide (13) for heating (5) to a temperature lower than the bonding temperature is provided. 6. The infrared heating apparatus according to claim 5, wherein the main heating light guide (12) and the peripheral heating light guide (13) are connected to the same light source (16).