JPH0215873A - Liquid purifying device for soldering device - Google Patents

Abstract

PURPOSE:To operate the purifying device only when an inactive liquid has been contaminated and to improve the operation rate of the device by detecting a degree of contamination of the inactive liquid which has been contaminated by a flux, etc., and purifying it, at the time of soldering electronic parts on a substrate by high temperature saturated vapor of the inactive liquid. CONSTITUTION:A substrate 22 on which electronic parts to be soldered have been placed is carried into a reflow part having a reflow tank 11 of an inactive liquid by a conveyor 5, the inactive liquid in the tank 11 is heated and evaporated by a heater 12, inactive saturated vapor of a high temperature is generated, and by its heat, the electronic parts are soldered onto the substrate. In this process, when the inactive liquid is contaminated by a soldering use flux and has been returned into the reflow tank 11, whether the inactive liquid has been contaminated or not is detected by infrared-ray detectors 23, 23', and only when said liquid has been contaminated, a controller 24 operates a switch 25, the contaminated inactive liquid is purified through a filter 26 of a purifying device 15 by a pump 27, and returned to the reflow tank 11. Since the purifying device 15 is operated only when the inactive liquid has been contaminated, the operation rate of the purifying device 15 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid purification device for a soldering device using an inert solvent.

2. Description of the Related Art In recent years, there have been some remarkable devices that automatically attach electronic components to printed circuit boards. At the same time, there has been a demand for devices that solder electronic components on printed circuit boards to be faster and more reliable. Among them, in the method of using an inert liquid in the soldering equipment, heating it to saturated steam, and melting the solder with the heat, this inert liquid was contaminated with impurities such as flux.

Conventionally, as shown in Fig. 4, a purifier 16 was used to visually check the liquid for dirt and circulate it manually. By setting a certain period of time, the liquid was periodically circulated to the purifying device 16 to purify the liquid. There is also a method of purifying the water by constantly circulating it in the purifier 16 as shown in (b). There is also a device that counts the number of processed substrates 22 and periodically circulates and purifies them to the purifying device 16 for a certain period of time.

In addition, in FIG. 4, 6 is a conveyor that conveys the board 22 on which electronic components are mounted, 13 and 14 are piping, and 27
is a pump, 11 is a reflow tank, 32 is a heating section, 33
29 is a cooling unit, 29 is an optical sensor, 3o is a counting device, and 31 is a pump drive command device.

Problems to be Solved by the Invention However, in the conventional method, the purification device operates regardless of the concentration or contamination of the inert liquid itself, resulting in waste, inappropriate liquid management, and high cost. This was causing a growing problem.

Means for Solving the Problems The means of the present invention for solving the above problems is a reflow process in which an inert liquid is heated with a heater, the solder on the board is melted with inert saturated steam, and solder is applied. A reflow tank for stocking the inert liquid, and a purification device connected to the reflow tank, and a control device for detecting the impurity concentration of the inert liquid in the reflow tank circulates it to the purification device. be.

Operation: According to the above-mentioned means, the control device makes a judgment based on the concentration and dirt of the inert liquid in the reflow tank, operates the purification device, and circulates the inert liquid through the reflow tank and the purification device.

Embodiment FIG. 1 shows an overall view of a soldering device as an embodiment of the present invention, and FIG. 2 shows a detailed sectional view of the same soldering device. The configuration of the soldering device will be described below with reference to FIG.

1 shows the entire soldering apparatus, and includes a loading section 17. The substrate 22 is divided into a preheating section 18, a reflow section 19, and a cooling/unloading section 2°, and the substrate 22 is conveyed by a conveyor 5. 2 indicates the entrance of the substrate 22, and the substrate 22 is carried in in the direction (arrow). The preheating section 18 includes an upper preheating heater 3;
A lower preheating heater 4 is provided, and an electric panel 16 is placed at the lower part.

The reflow section 19 is provided with an exhaust port 6 at the inlet and an exhaust port d at the outlet, and a reflow tank 11 and a heater 12 are installed at the lower center, into which an inert liquid is charged.

A cooler 7 is provided on both sides of the steam outlet 21,
A purification device is provided at the lower left side of the reflow section 19 to remove impurities contained in the cooled and condensed liquid.

The exhaust ports 6 and 6' are connected to the exhaust gas recovery section 1° so that the exhaust gas is sucked in the direction of arrow B. The unloading section 20 is provided with a cooling fan 8 that cools the substrate 22.
A drive motor 9 for driving the conveyor 6 is provided.

The reflow tank 11 is provided with an infrared detection device 23°, 23', and then a control device 24, and output is performed according to a wavelength and transmittance arbitrarily set in the control device 24 in advance. Depending on the output, the switch 26 is turned on and off, and the pump 26 is operated and stopped. Pipes 14 and 13 are provided from the reflow tank 11 and connected to a purification device 16. This purifying device 16 has a built-in filter 28 and a pump 27.

Next, the operation will be described with reference to FIGS. 1 and 2.

After the electronic components are mounted on the board 22, they are transferred to the preheating section 18, which is transferred in the forward direction to the loading section 17 of the device 1, and the board 22 is heated by the upper preheating heater 3 and the lower preheating heater 4.
is preheated. Furthermore, the substrate 22 is transported to the reflow section 19. The inert liquid in the reflow tank 11 is heated by the heater 12 to generate inert saturated steam, which is blown out from the steam outlet 21. The board 22 is heated here and soldered.

The substrate 22 is then transported through the reflow section 19, cooled by the cooling fan 8 at the unloading section 26, and unloaded in the A' direction.

When the inert liquid in the reflow tank 11 is heated and turned into inert saturated vapor to solder the board 22, flux and the like in the solder enters the inert liquid and the liquid becomes contaminated. In Figure 3, the vertical axis shows transmittance and the horizontal axis shows wavelength. In this figure, flux etc.
At wavelengths between -b, it exhibits the characteristics shown in the figure, and usually b -
As shown in the wavelength graph between c and d, equilibrium is maintained, and the wavelength between c and d shows an unstable region. As a result of this action, as shown in FIG. 2, the control device 24 determines the concentration of the inert liquid based on the wavelength and transmittance using the infrared detectors 23 and 23' attached to the reflow tank 11. The signal is output and operates the switch 25. Then, the pump 27 operates, and the liquid in the reflow tank 11 passes through the pump 27 from the pipe 14, passes through the filter 26 of the purification device 16, removes impurities such as flux, and flows as shown by arrow C. It passes through the piping 13 and returns to the reflow tank 11 for circulation. Then, when the impurities are eliminated and the concentration drops to a certain value, the infrared detection devices 23 and 23' perform detection and turn off the amplifier switch 25. At this time, the entire device stops, and after completion of purification, operation automatically starts.

It is also possible to perform circulation within a certain period of time and automatically start operation.

Effects of the Invention As described above, according to the present invention, there is no need to perform purification regardless of whether the liquid is contaminated, as in the past, so it is possible to reduce costs and increase the reliability of purification bags and placement. Moreover, since it is based on the wavelength and transmittance of infrared rays, impurities in the inert liquid can be reliably detected, allowing better liquid management.

[Brief explanation of the drawing]

FIG. 1 is an overall front view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of the essential parts, and FIG. 3 is a characteristic diagram of infrared wavelength and transmittance.
FIG. 4 is a front view of the conventional example. 1... Soldering device, 3, 4... Preheating heater 6... Conveyor, 8... Cooling fan, 11... Reflow tank , 12...
...7111 thermal heater, 15...purification device,
23... Detection device, 26... Name of filling agent, patent attorney Shigetaka Awano, and one other person.

Claims (1)

[Claims] a reflow section that heats an inert liquid with a heater and melts the solder on the board with inert saturated vapor to perform soldering; a cooling section that cools the inert saturated vapor and recovers the inert liquid;
An exhaust recovery section that sucks and recovers steam discharged from an exhaust port provided in the reflow section, a purification device that removes impurities from the recovered inert liquid, and an impurity in the reflow tank provided in the reflow section. Detects impurity concentration in active liquids,
A liquid purification device for a soldering device, comprising: a control device that controls the inert liquid to be circulated to the purification device when an impurity concentration is higher than a predetermined value.