JPH04313048A - Sprayed-flux monitoring apparatus - Google Patents

Abstract

PURPOSE:To monitor the state of the concentration of flux in a fog state always in high accuracy regardless of the concentration of the flux in a liquid state and to monitor the applied amount of the flux on a printed circuit board strictly when the flux is applied on the printed circuit board by spraying. CONSTITUTION:A flux spraying mechanism 12 is provided so as to face a printed circuit board 10 to be soldered through a spraying space. A light emitting mechanism emits light on the fog-state flux which is formed in a spraying space with the flux spraying mechanism 12. A light receiving mechanism detects the intensity of the light which is emitted from the light emitting mechanism and transmitted through the flux in the fog-state flux F or the intensity of the light reflected from the flux in the fog-state flux F. These mechanism are provided in this constitution.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a spray flux for monitoring the concentration state of atomized flux formed by a flux spray mechanism for spraying flux onto a printed circuit board to be soldered. Regarding monitoring equipment.

0002

[Prior Art] Generally, in the process of soldering a printed circuit board, it is necessary to apply flux to the printed circuit board as a preliminary step. Therefore, in the past, air was blown into the liquid flux to make it foam. A method is used in which the flux is brought into contact with the printed circuit board, or a method in which flux is sprayed and applied to the printed circuit board. In order to control the amount of flux that actually adheres, the concentration of the liquid flux is adjusted by monitoring the specific gravity of the flux.

On the other hand, liquid flux usually contains about 10% by weight of rosin component as an active ingredient, but it is difficult to remove the remaining rosin component from the printed circuit board after the soldering process is completed. Freon is usually used as a cleaning liquid in cleaning for this purpose. However, the use of fluorocarbons must be discouraged from the standpoint of preserving the global environment. Under these circumstances, it is possible to reduce the concentration of the rosin component in the liquid flux to, for example, 2 to 4% by weight, thereby reducing the amount of rosin component remaining on the printed circuit board after the soldering process is completed. There is a possibility that the process can be made virtually unnecessary.

0004

[Problem to be Solved by the Invention] However, in such a low-concentration liquid flux, the change in specific gravity corresponding to a change in concentration is minute, so it is difficult to adjust the concentration by monitoring the specific gravity. Therefore, there is a problem in that it is not possible to sufficiently control the amount of coating applied to the printed circuit board. Also, when applying flux by spraying, although it is possible to change the amount applied by changing the temperature of the liquid flux, the conveyance speed of the printed circuit board, and the spray conditions, the mist that is formed Because it is not possible to adequately monitor the flux concentration state,
There is a problem in that it is not possible to strictly monitor and control the coating state with high fidelity.

[0005] The present invention solves the above problems,
When applying flux to a printed circuit board by spraying, the concentration state of the atomized flux can always be monitored with high accuracy regardless of the concentration of the liquid flux used, and therefore the amount of flux applied to the printed circuit board can be monitored with high accuracy. The purpose of the present invention is to provide a spray flux monitoring device that can strictly monitor spray flux.

[0006]

[Means for Solving the Problems] In the spray flux monitoring device of the present invention, a flux is formed in the spray space by a flux spray mechanism provided so as to face the printed circuit board to be soldered through the spray space. a light-emitting mechanism that projects light onto the mist-like flux; and a light-receiving mechanism that detects the intensity of the light projected by the light-emitting mechanism and transmitted through the mist-like flux or the light reflected by the mist-like flux. It is characterized by

[0007]

[Operation] According to the spray flux monitoring device of the present invention, liquid flux is sprayed in the spray space to form a mist flux, which contacts the printed circuit board to achieve flux application. The application state corresponds to the concentration state of the atomized flux, and since the light that passes through the atomized flux or the light that is reflected by the atomized flux is detected, the concentration state of the atomized flux can be detected with high accuracy. . Therefore, by adjusting the factors that affect the concentration state of the atomized flux or other application conditions according to the detection results, it is possible to control the amount of flux applied to the printed circuit board to a desired state with high precision. This allows flux application to be achieved at or near the minimum amount required for, for example, a soldering process.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram showing an example of the basic configuration of a spray flux monitoring device according to the present invention. In FIG. 1, reference numeral 10 denotes a printed circuit board to which flux is to be applied, and is conveyed along a conveyance path P by a conveyance mechanism such as a belt conveyor. 12 is a flux spray mechanism, which is used to spray the printed circuit board 10;
A spray space S whose outer periphery is defined by a guide plate 18 is provided below the spray space S. The flux spray mechanism 12 in this example is of an air spray type, and the spray gun 1 has an upward nozzle.
3 is connected to a flux supply pipe 14 and an air supply pipe 15, and the flux is sprayed toward the flux spray mechanism 12 above to form a mist flux F in the spray space S.

[0009] A projector 20 is provided that projects light L1 toward the mist flux F acting on the printed circuit board 10, and transmitted light projected from the projector 20 and transmitted through the mist flux F is provided. A light receiver 22 is provided for receiving L2 and detecting its intensity. Here, as the light projector 20, for example, a light emitting diode, a light emitting lamp, a laser oscillator, or others can be used. Further, as the light receiver 22, a photoelectric element, a charge-coupled device, or other light receiving mechanism can be used, but one that emits an electric signal corresponding to the intensity of the received light is particularly preferable.

A monitor receiver 26 for monitoring the light intensity via a half mirror 25 is provided on the optical path of the light L1 from the projector 20 to the atomized flux F. The intensity of the light emitted is monitored. Further, in order to prevent the flux scattered from the atomized flux F from adhering to the light emitting window of the emitter 20 and the light receiving window of the light receiver 22, an appropriate flux adhesion prevention mechanism, such as an air injector 28, is provided. There is. This flux adhesion prevention mechanism is shown only for the light receiver 22 in FIG.

According to the above configuration, the flux spray mechanism 12 forms the atomized flux F in the spray space S, and when this comes into contact with the printed circuit board 10, the flux is applied to the lower surface of the printed circuit board 10. Ru. Then, the light L1 from the light projector 20 passes through the atomized flux F, and the transmitted light L2 is received by the light receiver 22, the light intensity is detected, and an electric signal corresponding to this is output.

However, when the light L1 with the intensity I0 is incident on the foggy flux F and the transmitted light L2 with the intensity It is detected by the light receiver 22, the degree of attenuation of the intensity of this light is determined by the degree of attenuation of the intensity of the foggy flux F. It corresponds to the concentration state. Moreover, the concentration state of the atomized flux F is particularly limited to minute droplets of the liquid flux in the atomized flux F (
Since it corresponds to the size and density of spray particles), the concentration state of the atomized flux F can be monitored by detecting the intensity of the transmitted light L2 by the light receiver 22.

As described above, since the detection result of the light receiver 22 corresponds to the concentration state of the mist flux F, the detection result of the light receiver 22 is used to determine the concentration state of the mist flux F. By adjusting factors that affect flux and other application conditions, the amount of flux applied to the printed circuit board can be controlled with high precision to a desired state. For example, by adjusting the supply ratio of liquid flux through the flux supply pipe 14, the air supply ratio through the air supply pipe 15, the temperature, concentration, etc. of the supplied liquid flux, the flux spray mechanism 12
It is possible to control the operating state of the Further, by controlling the position of the spray gun 13 or the conveyance speed of the printed circuit board 10, the conditions for coating can be adjusted.

As described above, according to the present invention, the concentration state of the mist flux, which is a direct flux source for the printed circuit board, is detected by transmitted light or reflected light, and the concentration state of the liquid flux used is detected. Since this detection can be carried out independently of the soldering process, it is possible to precisely control the state of flux application to the printed circuit board, and even when using a liquid flux with a low concentration, it is possible to Flux application can be achieved at or near the minimum amount required. Therefore, the amount of rosin component remaining after the soldering process is completed can be reduced to a very small amount, making cleaning of the component virtually unnecessary.

The flux spray mechanism to which the spray flux monitoring device according to the present invention is applied is not limited to a specific one, and can form a mist of flux using liquid flux, and can spray flux onto a printed circuit board. Any material that can be applied may be used. Therefore, methods other than the air spray method in which air is applied to the liquid flux, such as a spray method in which the pressure of the flux itself is increased and it is ejected from micropores, and an atomization method using the cavitation effect of the liquid flux using an ultrasonic vibrator, etc. It can be applied to any type of flux spray mechanism.

In the present invention, as shown in FIG. 2, a light receiver 30 is provided in place of the light receiver 22 for detecting the intensity of the reflected light L3 obtained by reflecting the light L1 from the projector 20 by the atomized flux F. It is also possible to have a configuration, and in this case as well, the same effects as described above can be obtained. However, it is preferable to detect the light that has passed through the atomized flux F because the reliability of the detection result is high, especially in terms of the fidelity corresponding to the state of the atomized flux F.

[0017]

As described above, according to the present invention, with a simple configuration, when applying flux to a printed circuit board by spraying, it is possible to spray the flux with high precision regardless of the concentration of the liquid flux used. Accordingly, it is possible to provide a spray flux monitoring device that can monitor the state of the flux, and therefore can strictly monitor the amount of flux applied to a printed circuit board.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram schematically showing the configuration of an embodiment of a spray flux monitoring device of the present invention.

FIG. 2 is an explanatory diagram schematically showing the configuration of another example of the spray flux monitoring device of the present invention.

[Explanation of symbols]

10 Printed circuit board P Conveyance path 12 Flux spray mechanism 18 Guide plate S Spray space 13 Spray gun 14 Flux supply pipe 15 Air supply pipe F Atomized flux 20 Floodlight 22 Photo receiver 25 Half mirror 26 Monitor receiver 28 Air injector L1 Projection light L2 Transmitted light L3 Reflected light

Claims (1)

[Claims] 1. A light-emitting mechanism for projecting light onto atomized flux formed in the spray space by a flux spray mechanism provided so as to face a printed circuit board to be soldered via a spray space; A spray flux monitoring device comprising: a light receiving mechanism that detects the intensity of light projected from a light emitting mechanism and transmitted through the atomized flux or light reflected by the atomized flux.