JP2000013007A - Local flux application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device, to reduce equipment cost and to set the use quantity of flux minimum by putting flux into a sealed container where small holes are made in proper parts and connecting a pipe through which the gas of air flows. SOLUTION: A container 1 is inclined or flux 2 is made to flow into a container 1 or it is made to flow out from it. Flux liquid is made to adhere to the inner opening parts of small holes opened by adjusting them to a pad being the soldering part of a substrate at the upper part of the container 1. A plurality of small holes 3 are filled with flux 2 immediately after by the operation of capillary phenomenon. When the gas of air is made to flow into the container from a connected gas flow-in tube 4, flux 2 in the small holes is ejected with pressure and it is adhered to the soldering part of the substrate close to the container. Thus, the enlargement and complication of a device and cost rise owing to misting can be dissolved and the consumption quantity of flux can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local flux applying apparatus for soldering a printed circuit board on which electronic components are mounted.

[0002]

2. Description of the Related Art A previously developed local flux coating apparatus for soldering has a structure as described in Japanese Patent Application Laid-Open No. 9-74272. That is, a spray mask is provided between the mist flux blown out from the spray nozzle and the substrate soldering surface, and the flux is locally applied only to the opening. With this mechanism, it has become possible to eliminate the adhesion of flux to unnecessary portions, which has been an issue so far. As a result, a substrate on which components that do not want to adhere to a flux can be processed in a series of soldering steps, and the substrate cleaning required to remove the flux residue after the soldering can be more easily or omitted. .

[0003] Many electronic components that are easily affected by the adhesion of flux, such as variable resistors, trimmers, switches and connectors, are difficult to withstand cleaning. In addition to the above, washing is a waste liquid treatment,
This has led to technical problems such as replacement products and an increase in processing costs caused by devices having advanced processing functions. The reason for reducing the solid components such as rosin and requiring a low-viscosity flux was to minimize the effect of the flux residue after soldering on the substrate even without cleaning. The fluxer mechanism was also changed from spraying to foaming due to its viscosity change, but the board that still requires precise soldering must be cleaned by flux removal and installed in the subsequent process There are many parts that dislike flux.

[0004]

The flux application mechanism using a spray nozzle can freely adjust the amount of application to adhere to a substrate. In order to uniformly apply an appropriate amount, it is necessary to make the mist sprayed from the nozzle finer and to spray a constant amount toward the substrate surface. However, since a considerable amount of flux that is scattered and does not adhere to the substrate surface is also generated, exhaustion, filtration, recovery, and the like by forced blast in a sealed and covered apparatus are important elements of the apparatus. If this function is not sufficient, the flux that has penetrated into unnecessary parts on the substrate surface often has unexpected effects on movable parts and electrical contact parts. The device for preventing this is large, including the blower fan and duct, requires a complicated mechanism, and the installation cost is also increased.

[0005] Further, there is a lot of waste from the viewpoint of the amount of flux used. That is, the flux is an element for proper soldering only when it is applied to the soldering location. Flux mist that does not adhere to the substrate is discarded without its use.
Even if it adheres to the substrate, if it is separated from the pad, which is the soldering point, it will not be used again and its effect will not be exhibited. A small amount, perhaps a few hundredths, of the sprayed flux serves only its intended purpose of cleaning the soldering surface and increasing its wettability.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and in a fluxer device for local application, a required amount of flux is applied only to a soldering surface by a simple mechanism, so that the flux is scattered to unnecessary portions. It is an object of the present invention to provide a mechanism capable of preventing soldering, reducing the number of post-processed parts, performing more stable soldering, reducing the size of the apparatus, lowering the equipment cost, and additionally minimizing the amount of flux used.

[0007]

In order to achieve the above-mentioned object, in a local flux application apparatus according to the present invention, first, a flux is put into an airtight container having a small hole at an appropriate place, and gas such as air is introduced. It is a tube connected.

[0008] The position where a small hole is formed in the closed container is preferably provided on the upper surface, side surface or lower surface of the container, which is suitable for applying the solution by approaching or contacting the substrate.

It is preferable that the shape of the small hole provided in the closed container is formed in a shape and size that can apply a required amount to a required portion of the substrate flux, and that a small-diameter pipe is connected outside the small hole.

Further, a flux supply plate may be provided inside the closed container, and the small hole of the supply plate opened there and the small hole opened in the container may be overlapped or separated with the movement of the flux supply plate. it can.

Further, it is effective to provide a spray nozzle capable of spraying and supplying the flux inside the closed container.

[0012]

In the local flux applicator constructed as described above, first, the container is tilted, or the flux flows into and out of the container, and the flux liquid adheres to the inner opening of the small hole opened in the container. Let it. Immediately thereafter, the small holes are filled with flux by the action of capillary action. Next, when a gas such as air flows into the container from the connected gas inflow pipe, the flux in the small hole is ejected by the pressure and adheres to the soldering portion of the substrate close to the container.

The shape and size of the small hole depends on the cross-sectional shape and depth of the small hole, the pressure and time of the gas flowing into the small hole. For example, if the opening of the small hole is a small circle, the surface of the substrate is almost circular. And wrap the pad and the soldered part of the terminal in a film shape. At this time, the viscosity and surface tension of the flux act, so that the flux does not form a net or scatter. Further, even when a large number of small holes are provided in the container, the low-viscosity flux does not fly out almost simultaneously and remains in the small holes. If injection is performed while tilting toward two pads on the substrate from two or more small holes, more reliable coating can be performed.

The amount by which the flux adheres to the substrate and spreads is greatly affected by the volume of the small hole formed in the container. Therefore, regardless of the thickness of the container, a flux supply plate is provided in the container to supply an optimal amount of the injection to the small hole. The plate should be of appropriate thickness and a supply plate eyelet of the same shape should be drilled at the same position as the hole drilled in the container when stacked. First, the flux supply plate is immersed in the flux liquid in the container, and the flux is accommodated in the small hole of the supply plate. Then, the flux supply plate is placed on the small hole of the container from the inside to increase the gas pressure in the container, and the flux is attached to the substrate through the small hole of the container.

The flux ejected from the small hole by increasing the gas pressure in the container spreads as a single liquid particle on the substrate. The gas pressure to be injected into the container increases rapidly, and if the injection speed is high, the surface spread on the substrate becomes large.On the contrary, if the gas pressure is not sufficiently increased, the flux in the small hole does not reach the substrate surface and the small hole There is a tendency to diffuse to the outer periphery. Therefore, a small-diameter liquid feed tube is connected to the opening of the small hole, the tip of the tube is brought into contact with or close to the coating surface of the substrate, an appropriate amount of flux is supplied from the inner surface of the small hole to the container, and the pressure inside the container is slowly increased. Since the flux liquid is slowly carried through the liquid feed pipe and comes into contact with the substrate, an appropriate amount of flux is surely applied in a predetermined size, shape and concentration.

The flux contained in the small hole opened in the container is sucked up from the inside of the container by capillary action.
If a large amount of flux liquid is in contact with the small hole, the inside of the small hole is immediately filled with the liquid. If a small amount of film-like liquid is in contact, an amount corresponding to the thickness of the liquid film is supplied to the small hole. Therefore, by spraying the flux with a spray nozzle to infiltrate the inner surface of the container and adjusting the amount of the adhering liquid, it is possible to store an optimal amount of liquid in the small hole.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to the drawings. In FIG.
A plurality of small holes 3 are provided in the upper part of the container 1 in accordance with pads which are soldered portions of the substrate, and a gas inflow pipe 4 which allows gas such as air to flow into the container 1 to increase the internal pressure thereof is connected.

In the embodiment shown in FIG. 2, a small hole 3 is provided on the side surface or bottom surface of the container 1 in the embodiment shown in FIG.

In the embodiment shown in FIG. 3, in the embodiment shown in FIG. 1, the small hole 3 provided in the container 1 is not made cylindrical, but is made to have a shape corresponding to the pad of the substrate, or is perpendicular to the substrate surface. Keep it open without tilting.

In the embodiment shown in FIG. 4, in the embodiment shown in FIG. 1, a flux supply plate 5 is provided inside the container 1, and the flux supply plate 5 is provided in the small-diameter hole 3 of the container 1. At the same time, the supply plate small hole 6 is opened, and the small hole 3 and the supply plate small hole 6
The flux supply plate 5 can be moved so as to overlap or come apart.

In the embodiment shown in FIG. 5, of the embodiment shown in FIG. 1 or FIG. 4, small-diameter liquid feed pipes 9 having the same length are connected to the small holes 3 opened in the container 1, respectively. deep.

In the embodiment shown in FIG. 6, a spray nozzle 7 capable of spraying a flux is provided inside the container 1 in the embodiment shown in FIG.

[0023]

Since the present invention is configured as described above, it has the following effects.

In the conventional spray fluxer, the fine adjustment of the amount applied to the substrate has been performed by the concentration and time of the mist in which the flux liquid is finely crushed by the pressure of air and brought into contact with the substrate surface. This was the best method that could prevent an instantaneous excessive infiltration if the substrate was brought into direct contact with the flux liquid level, and that a proper amount of coating could be applied. However, in order to perform a sufficient coating even on the details of the board on which the components are mounted, it is necessary to bring a flux mist having a uniform concentration into contact with the board surface for a certain time. Therefore, the scattering of the flux described above is an inevitable result, and the exhaust gas recovery device is also a necessary mechanism.

In these apparatuses, the flux liquid is first turned into a mist and adheres to the substrate surface one after another. As described above, the amount of adhering can be adjusted in the process, but the mist in contact with the substrate surface is liquefied due to the superposition of fine particles, and becomes an appropriate amount. Therefore, if the required amount of flux liquid can be brought into contact with a specific part of the substrate, excessive infiltration will not occur, fulfilling the purpose of the fluxer, and eliminating the large size, complexity, and high cost of the mist generated device And the flux consumption can be greatly reduced.

A local flux application device that accommodates a flux liquid in a closed container and applies an appropriate amount of a solution only to a required portion of the substrate in a solution state does not cause the flux to scatter outside the container. Therefore, in the soldering process of the board, the electronic components that were naturally required to be mounted on the board in a separate process as a post-installation in order to avoid the adhesion of the flux by omitting or simplifying the cleaning are also soldered in a series of processes. It has become possible.

Regarding the above-mentioned mechanism for supplying an appropriate amount of flux to the small holes by spraying into the container, the container has a small volume, and since it is sealed, neither scattering nor evaporation of the solvent occurs, and the container contacts the inner surface of the container. The flux which returns to a liquid state and can be easily recovered can be sprayed again without causing waste.

In addition, there is no need for a blower fan or duct for exhausting and filtering, which has been seen in conventional spray fluxers, there is no need to move nozzles for uniform application, and the driving mechanism is minimized to simplify the apparatus. , Miniaturization and equipment cost can be reduced.

Further, the scattering of the flux and the unnecessary application of the flux are eliminated, and the required amount of the applied liquid is applied only to the required portions, so that the amount of the flux used can be drastically reduced, thereby contributing to the reduction of the soldering cost. For the same reason, cleaning and maintenance of the apparatus have been facilitated.

In addition, since the mechanism is simple, small, and has a small number of driving parts as described above, the compressed gas to be used and the amount of electric power can be minimized. There is no air pollution and no noise such as blowers. The equipment is designed with consideration for the surrounding environment, including the simplification of the cleaning process.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a local flux application device.

FIG. 2 is a longitudinal sectional view showing an embodiment in which a small hole is formed in the bottom surface of the container.

FIG. 3 is a longitudinal sectional view showing an embodiment in which the shape of the small hole is adjusted to the shape of a pad.

FIG. 4 is a longitudinal sectional view showing an embodiment in which a flux supply plate is provided.

FIG. 5 is a longitudinal sectional view showing an embodiment in which a liquid feed pipe is connected to a small hole.

FIG. 6 is a longitudinal sectional view showing an embodiment in which a spray nozzle is provided in a container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Flux 3 Small hole 4 Gas inflow pipe 5 Flux supply plate 6 Supply plate small hole 7 Spray nozzle 8 Substrate pad 9 Liquid feed pipe 10 Flux coating substrate

Claims (6)

[Claims] 1. A container (1) in which a flux (2) is stored, a plurality of small holes (3) are opened on the upper surface in accordance with a soldering position of a substrate, and a gas inflow pipe (4) is connected. Also, a local flux application device. 2. The local flux application device according to claim 1, wherein a plurality of small holes (3) are formed in a side surface or a bottom surface of the container (1). 3. The shape of the openings of the plurality of small holes (3) formed in the container (1) is adjusted to the respective soldering positions of the substrate, or the shapes of the openings are inclined with respect to each other, so that two 2. The local flux applicator according to claim 1, wherein the at least one small hole has an open end. 4. A supply plate small hole (6) opened in accordance with a small hole (3) provided in the container (1), and the small hole (3) and the supply plate small hole (6) come into contact with each other and may be separated. The local flux applicator according to claim 1, characterized in that a flux supply plate (5), which is movable as possible, is provided inside the container (1). 5. The local flux applying apparatus according to claim 1, wherein a plurality of small holes (3) opened in the container (1) are connected to liquid feeding pipes (9) having the same length. 6. The local flux application device according to claim 1, further comprising a spray nozzle (7) for spraying a flux into the container (1).