JPH0214856Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The invention is applied to an automatic soldering device for soldering printed circuit boards installed in electronic equipment, communication devices, measuring instruments, etc. The present invention relates to a flux quality control device that constantly maintains the quality of flux in an attached device, and more particularly to a flux quality control device that adjusts the concentration, temperature, purity, etc. of flux.

<Prior Art> In general, in order to maintain the high quality of soldered printed circuit boards, one condition is to ensure that a good flux application process is achieved before soldering. Ru. Therefore, in automatic soldering equipment, various measures have been taken to ensure that the quality of the flux in the flux tank, specifically the concentration, purity, etc., is maintained at a good and constant level. Ta. For example, JP-A-51
-24556 Publication, JP-A-49-11159 Publication, Utility Model Publication
As shown in Publication No. 52-101464, etc., first, the specific gravity of the flux in the flux tank is measured using an electromagnetic or optical detection means, and at the same time, the temperature of the flux is measured using a temperature sensor, etc., and this temperature value is measured. Based on this, the measured value of flux specific gravity is corrected to determine the accurate concentration of flux, and the amount of flux stock solution and diluent supplied to the flux tank is adjusted so that the determined flux concentration value is always kept within an appropriate range. A flux concentration control method has been proposed and developed.

<Problems to be solved by the invention> However, these conventional concentration control means require a correction calculation circuit for calculating an accurate flux concentration based on the measured flux specific gravity value and the measured temperature value, and a Based on the value, concentration control requires various complex components such as control circuits and mechanisms to keep the flux concentration in the flux tank always within the most activated range while responding to changes in flux temperature. The cost of the entire device becomes high.

In addition, in general, when the flux is at a temperature of 18°C or higher, it has an appropriate viscosity and is activated.
If the temperature exceeds 25°C, the amount of evaporation of the diluent in the flux becomes very large, which is economically disadvantageous. Therefore, the flux is suitable for good application to printed circuit boards in the temperature range of 18°C to 25°C, especially at temperatures of about 20°C. However, in the past, few special measures were taken to maintain the flux at a suitable temperature and at a constant temperature, and even if such measures were taken, they were of complicated mechanisms.

Further, in conventional automatic soldering apparatuses, the concentration of flux tends to become non-uniform within the flux tank, which has caused a problem in that subtle unevenness in flux application may occur.

Furthermore, in general, in order to obtain high-quality soldered products, one condition is to stably supply a flux free of impurities to a flux tank. Therefore, automatic soldering apparatuses have conventionally been required to be equipped with a mechanism that satisfies this condition.

The present invention was developed in consideration of the above-mentioned circumstances, and its purpose is to maintain the flux in the flux tank at a uniform concentration and constant temperature, and to maintain high purity at all times. An object of the present invention is to provide a flux quality control device that is simplified.

<Means for solving the problem> The flux quality control device of the present invention connects the flux tank of an automatic soldering device and a pump through two reciprocating routes, and forms a circulation system in which flux circulates by operating the pump. , and each tank for flux stock solution and diluent is connected to the circulation system, heating means and/or cooling means are provided in the outward path of the circulation system, and a filter is connected to the return path of the circulation system. It is characterized by:

The heating means and cooling means used in the present invention are any means that can heat or cool the flux flowing in the outward path of the circulation system and bring the flux in the flux tank to the desired temperature (18°C to 25°C). As a heating means, for example, an electric heating coil arranged around a flux flow path or a structure that blows hot air into a flux flow pipe is used, and as a cooling means, for example, a water jacket is placed around a flux flow path. A method in which the flux is formed near the pipe or a method in which the flux is caused to flow into a cooled metal tube are applicable. For temperature control, heating means are usually used, but in summer when the temperature exceeds 25°C, it is necessary to use cooling means.

In addition, the filter of the present invention includes a filter material such as filter paper, filter cloth, and fibrous filter material that can remove impurities and foreign substances from used flux and regenerate the flux into a flux that has no or almost no contamination of these substances. Applicable.

<Operation> In the present invention, by operating the pump in the circulation system, the flux circulates and flows, that is, it is supplied from the tank to the flux tank, flows through the tank, is recovered from the tank, and then returns to the flux tank again. As a result, a substantially constant flow of flux is formed inside the flux tank, and the concentration distribution of the flux becomes uniform. Furthermore, the temperature of the flux circulating flow can be made uniform by the action of the heating means and the cooling means. Furthermore, in the present invention, foreign matter and impurities are removed from the circulating flux by the function of the filter.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 1 indicates a flux tank of an automatic soldering apparatus, and 3 and 4 indicate a pump unit and a control unit for maintaining the quality of the flux 2 in the tank 1. A circulation system 6 is formed by connecting the pump 5 in the pump unit 3 and the flux tank 1 through two reciprocating paths, and when the pump 5 is operated, the flux 2 circulates and flows, that is, the flux 2 is supplied from the pump 5 to the flux tank 1. It flows inside the tank 1 as shown by arrow A and is collected from the tank 1 by the pump 5. As the pump 5, a conventionally used liquid supply pump may be applied.

The outgoing path 7 of the circulation system 6 includes a heating means 9 of an electric heating coil and a cooling means 10 of a cold metal tube.
are provided in parallel with the pump 5 via a two-way valve 11, while a filter 18 is connected together with the valve 14 in the return path 8 of the circulation system 6. Further, in the circulation system 6, a flux stock solution tank 12 and a diluent tank 13 are connected to a valve 1.
4', 14''.

Furthermore, a specific gravity sensor 15, a liquid level sensor 16, and a temperature sensor 17 are provided at the upper part of the flux tank 1, and each sensor 15, 16, 17
is electrically connected to the control unit 4. The specific gravity sensor 15 is a sensor that detects the specific gravity of the flux based on the stop position of the float, and the liquid level sensor 16 detects the flux level within the allowable range depending on the contact between the three probes and the flux liquid surface. The temperature sensor 17 is a sensor that detects the temperature of the flux using a function such as a thermocouple. In addition to this, a life sensor may be provided that detects flux contamination based on light transmittance. The values detected by these sensors are sent to the control unit 4.
displayed on the panel. The flux concentration value is
Although it is possible to obtain the specific gravity value, temperature value, etc. detected by an arithmetic circuit (not shown),
The apparatus of this embodiment does not operate the mechanism of the pump unit 3 based on this concentration value to control the flux concentration in the tank 1, but merely indicates the actual flux concentration value for confirmation.

When using this device, first open the valve 14 and connect the two-way valve 11 to a predetermined means, and then operate the pump 5 to pump the flux 2.
circulate. Along with this, the heating means 9 is operated during normal times, and the cooling means 10 is operated during the high temperature summer season.

During operation, when the flux concentration reading is lower than a predetermined standard, the control unit 4 opens the valve 14' of the tank 12 and supplies the flux stock solution to the circulation system 6. When the concentration is higher than the predetermined standard, the valve 14'' of the tank 13 is opened to supply diluent to the circulation system 6, and the functions of the means 9 and 10 are adjusted accordingly depending on the temperature reading of the flux 2. Ru.

In the apparatus of the example, the flux 2 in the flux tank 1 was constantly mixed by the steady turbulent flow A formed in the flux tank 1, so that the concentration distribution of the flux was uniform. Furthermore, the temperature of the flux was kept constant, and the flux 2 was maintained at a high purity due to the action of the filter 18.

<Effects of the invention> As explained above, the flux quality control device of the present invention has a structure that stabilizes the flow of flux in the flux tank and raises and lowers the temperature of the flux using special means. Since the concentration of flux in the tank can be kept uniform and the temperature constant, and impurities can be removed by a filter, high purity flux can be maintained at all times.

Furthermore, the device of the present invention does not require a complicated control mechanism to keep the flux concentration constant, has a simple structure, and is very inexpensive to manufacture.

[Brief explanation of the drawing]

The figure shows a flux quality control device according to an embodiment of the present invention. In the figure, 1...Flux tank, 2...Flux, 5...Pump, 6...Circulation system, 7...Outward path, 8...Return path, 9...Heating means, 10...Cooling means, 18 ...Filter.

Claims (1)

[Scope of utility model registration request] A flux tank of an automatic soldering device and a pump are connected through two reciprocating routes, a circulation system is formed in which flux is circulated by the operation of the pump, and each tank for flux stock solution and diluent is connected to the circulation system, A flux quality control device characterized in that a heating means and/or a cooling means are provided in the outward path of the circulation system, and a filter is further connected in the return path of the circulation system.