JPH06232541A - Flux application and device therefor - Google Patents

Abstract

PURPOSE:To enable flux to be evenly applied onto a printed board preventing flux from oozing out or bleeding by a method wherein post flux is applied onto the printed board as it is atomized. CONSTITUTION:When post flux 1 in a tank 4 is atomized by driving an ultrasonic vibrator 5, flux mist 2 is gradually gathered at the center by a flux guide 6 and made to gush out of a nozzle 6a. In this state, when a printed board is made to pass through above the nozzle 6 by a transfer means, post flux is applied onto the rear side of the printed board. The coating weight of post flux 1 is monitored by an optical sensor 3 and kept adequate corresponding to the conditions of a printed board. By this setup, flux can be not only restrained from oozing out to a contact component or bleeding to the surface but also applied to through-holes. Flux can be evenly and stably applied and restrained from increasing in consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux applying method used for flow soldering of a printed circuit board unit, and a flux applying apparatus used for the flux applying method.

In the printed circuit board unit, the post flux used for soldering is removed by cleaning in order to improve the appearance quality and maintain reliability. However, fluorocarbons and chlorine-based organic solvents used for cleaning have been determined to be totally abolished in order to protect the global environment, and development of a soldering technique that does not require cleaning is required.

For this reason, there is provided a flux which does not require cleaning after soldering. However, when applying the flux, a soldering failure occurs due to penetration into the contact portion, bleeding onto the surface, and uneven coating. ing. There is a need for a new flux coating method that solves these problems and enables coating.

[0004]

2. Description of the Related Art FIG. 2 shows a conventional example of a flux coating method. In this conventional example, the post flux 1 to be applied
After the foam tube 7 is put therein and the post flux 1 is bubbled, the bubbles are collected by the flux guide 6. The application of the flux 1 is performed by immersing the back surface of the printed circuit board in this bubble.

In this method, however, the amount of post flux 1 applied is large, the flux bleeds to the surface due to a capillary phenomenon, or contact failure occurs due to penetration into contact parts, and non-cleaning flux is applied. In this case, a stable foaming state could not be obtained in terms of characteristics, and there was a drawback that soldering failure was caused by uneven coating.

As a means for solving this, as shown in FIG. 3, a spray method in which pressure is applied to the flux 1 to spray it by the nozzle 6a and an ultrasonic method in which the flux is atomized and sprayed by ultrasonic waves are devised. Has been done.
In FIG. 3, 8 is a flux collector and 9 is a flux supply tank.

However, in this method, when the flux 1 is sprayed on the back surface of the substrate, the nozzle 6a is swung as shown by an arrow in FIG. In addition to the problem that the flux is not sufficiently supplied, the flux coating efficiency is poor and the external shape of the apparatus becomes large.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and prevents flux oozing and bleeding, and enables uniform coating without unevenness. It is intended to provide a coating method of.

[0009]

According to the present invention, the above object is to atomize a post flux 1 and then to atomize a flux mist 2 as shown in FIG. 1 corresponding to an embodiment.
This is accomplished by providing a flux application method in which a printed circuit board is passed over and the post flux 1 is applied to the printed circuit board.

[0010]

In the present invention, the post flux 1 is atomized by an appropriate means and then supplied to the coated surface of the printed circuit board. By making the post-flux 1 into a mist and then supplying it to the printed circuit board, uniform flux application becomes possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows a coating part of a flux coating device used for carrying out the method of the present invention. The coating section has a tank chamber 4 and a flux guide 6 installed in the tank chamber 4.

A post flux 1 is placed in the tank chamber 4, and a liquid level sensor 10 is installed on the wall surface of the tank chamber 4 in order to monitor the liquid level of the post flux 1. Further, a plurality of ultrasonic transducers (atomization device 5) are submerged in the tank chamber 4, and atomize the post flux 1 in the tank chamber 4.

The flux guide 6 will be described later.
The atomized flux mist 2 is formed in a trapezoidal shape in a side view so as to be concentrated toward the central portion, and the lower bottom portion is sunk in the tank chamber 4 so as to cover the ultrasonic transducer 5,
The nozzle 6a at the upper bottom is arranged so as to project above the tank chamber 4.

Further, an optical sensor 3 for monitoring the flow height of the flux mist 2 is provided above the tank chamber 4.
Is provided to control the amount of flux mist 2 flowing out according to the conditions of the printed circuit board, to control the amount of coating into the through holes, to bleed onto the surface, and to bleed onto contact parts, bleed onto the surface. Is being prevented.

Therefore, in this embodiment, first, when the ultrasonic vibrator 5 is driven to atomize the post flux 1 in the tank chamber 4, the flux mist 2 is gradually collected by the flux guide 6 in the central portion. Nozzle 6a
Wells out.

In this state, when the printed circuit board is passed over the nozzle 6a by a conveying means (not shown), the post flux 1 is applied to the back surface of the printed circuit board. As described above, the application amount of the post flux 1 is monitored by the optical sensor 3 and is maintained at an amount according to the conditions of the printed circuit board.

[0017]

As is apparent from the above description, according to the present invention, it is possible to prevent the bleeding on the contact parts and the bleeding on the surface and to enable the application to the through holes. it can.

Further, since it is possible to obtain a uniform and stable coating state without being influenced by the components of the flux, and since it is not necessary to spray at the time of applying the flux, the flux can be used without waste and the flux consumption amount can be reduced. Can be suppressed.

Furthermore, when the height of flux mist is detected by a sensor, the strength of the atomizing device can be controlled based on the detection result, and the optimum coating amount can be determined for each printed circuit board. It can be controlled easily.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, in which (a) is a front view,
(B) is a side view.

FIG. 2 is a view showing a conventional example, (a) is a front view and (b) is a side view.

FIG. 3 is a view showing another conventional example, in which (a) is a front view,
(B) is a side view.

[Explanation of symbols]

 1 Post Flux 2 Flux Mist 3 Sensor 4 Tank Chamber 5 Atomizer 6 Flux Guide 6a Nozzle

Claims (4)

[Claims] 1. A method for applying a flux, which comprises atomizing a post flux (1), then passing the printed circuit board over the atomized flux mist (2), and applying the post flux (1) to the printed circuit board. . 2. The print height of the flux mist (2) is detected by a sensor (3), and then the amount of atomization of the post flux (1) is controlled by the output of the sensor (3) to a printed circuit board. The method of applying flux according to claim 1, wherein the amount of post flux applied is controlled. 3. A tank chamber for storing post flux (1).
(4) and the post-flux deposited in the tank chamber (4)
An atomizing device (5) for atomizing (1) and the atomized flux mist (2) are collected, and the nozzle (6)
A flux applicator having a flux guide (6) for letting out from a). 4. A sensor (3) for monitoring the height of flux mist (2) flowing out from the tip of the nozzle (6a) is provided, and the operation of the atomizing device (5) is controlled by the output of the sensor (3). The flux applicator according to claim 3.