JPS61179594A - Washing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cleaning device, and particularly to a cleaning device suitable for cleaning printed circuit boards after soldering.

[Background of the invention]

In the printed circuit board assembly process, components are usually soldered to the board, and flux is used in this process to ensure soldering quality. If such flux remains on the printed circuit board, problems such as corrosion and poor electrical contact characteristics will occur, so the printed circuit board i is generally cleaned after soldering.

In cleaning operations, in order to efficiently remove such flux, cleaning solutions and cleaning methods that are appropriate for the shape and material of the flux and the object to be cleaned are selected.

In order to ensure cleaning quality, the cleanliness of the cleaning solution is a very important factor as well as the selection of such a cleaning method. By repeating cleaning with a certain amount of cleaning liquid, the flux is dissolved in the cleaning liquid, and the flux concentration in the cleaning liquid increases.

If something is cleaned with such a dirty cleaning solution, the cleaning properties itself will be damaged, and the originally clean surface will also become counter-contaminated, so in order to obtain high-quality cleaning properties, it is important to wash with a clean solution. is an important issue.

The flux concentration in the cleaning liquid must be 0.01% by weight or less for parts having electrical contact portions such as connectors; if the concentration is higher than this, poor contact will occur. 6th @
shows the relationship between the incidence of poor contact and the flux concentration in the cleaning solution, and it can be seen that the flux concentration required at the final stage of cleaning is 0.01% by weight or less.

In order to manage the flux concentration in the cleaning solution to a low concentration in this way, (1) the set distillation amount must always be obtained;

(ii) Increase the number of cleaning tanks as much as possible, and (city) constantly monitor and manage the flux concentration in the cleaning solution.

is valid.

Conventional apparatuses rely on empirical control methods without adequately controlling the amount of distillation and flux concentration, and as a result, printed circuit boards are subject to variations in cleaning quality.

[Purpose of the invention]

An object of the present invention is to provide a flux concentration meter that monitors and manages the flux concentration in a cleaning liquid.

[Summary of the invention]

The present invention provides a cleaning system that includes a cleaning tank that cleans an object to be cleaned with flux attached thereto with a cleaning liquid, and a distillation machine that inputs the cleaning liquid that has passed through at least one cleaning tank and is contaminated by cleaning, and outputs a clean cleaning liquid. equipment is assumed.

The present invention has a first container for taking a sample of clean wash liquid that is the output of the distiller and a second container for taking a sample of contaminated wash liquid after passing through one of the wash tanks. It is a flux concentration meter. Both the first and second containers are at least partially transparent and can transmit light. This flux densitometer includes first and second irradiation means that irradiate light having a wavelength in a specific region;
a first photometer that detects the amount of light emitted by the first irradiation means after passing through the first container; A second photometer that detects the amount of irradiated light compares the transmittance of light detected by the first photometer and the transmittance of light detected by the second photometer, and as a result, the transmittance by the flux is determined. and a control means for determining the ratio.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 4 is a cross-sectional view of the configuration of a printed circuit board cleaning device related to an embodiment of the present invention. This device consists of a first cleaning tank 1 and a second cleaning tank 2 for spray cleaning a printed circuit board 11, and a third cleaning tank 3 for performing immersion cleaning.
and first to third recovery tanks 4 to 6 for recovering the washed liquid, a first flap plate 7 and a second flap plate 8 for selectively flowing the washed waste liquid to the recovery tank. An upper substrate holding hanger 13 and a lower substrate holding hanger 12 for holding and transporting the substrate. It is comprised of a spray nozzle 10 for spray cleaning the substrate in the cleaning tank, a sliding head 14 for sliding the spray nozzle, and an opening/closing shutter 15 for preventing the cleaning liquid from scattering during spraying.

Note that there are five carry-in conveyors 19, a conveyor for conveying the printed circuit boards 11 to the cleaning device, and a discharge conveyor 20.
This is a conveyor that transports the printed circuit board 11 after cleaning.

Further, the upper hanger arm 18 is a transport mechanism for moving the printed circuit board 11 from one cleaning tank to another. The cleaning liquid 1 is in the third cleaning tank 3 and the first to third recovery tanks 4 to 6.
6 is stored or retrieved.

FIG. 5 shows the flow of the cleaning liquid 16 of this embodiment. In addition to those shown in FIG. The first to fourth liquid storage tanks 22 to 25, the flow meter 26 for monitoring the distillation amount, and the flux concentration meter 27 for monitoring the flux concentration in the cleaning liquid in the third cleaning tank 3, which is the final cleaning tank. configured.

In the first cleaning tank and the second cleaning tank in Fig. 5,
The phrases ``second cleaning'' and ``second cleaning'' indicate two steps performed in each cleaning tank and the flow of the cleaning liquid used at that time. Note that all the arrows in FIG. 5 indicate the flow and direction of the cleaning liquid.

Next, the flow of the cleaning liquid and its management method in this embodiment will be explained using FIG.

The clean washing liquid distilled by the distiller 28 is
After being stored in the liquid storage tank 25, it passes through a flow meter 26 and enters the third cleaning tank 3. The liquid overflowing from the third cleaning tank 3 flows into the third liquid storage tank 24, and the liquid overflowing from the third liquid storage tank 24 flows into the second liquid storage tank 2.
3, then overflows from the second liquid storage tank 23 to the first liquid storage tank 22, and returns to the distiller 28 while gradually increasing the flux concentration in the cleaning liquid.

As mentioned above, in order to obtain a clean surface with no electrical problems on the printed circuit board 11, the flux concentration in the cleaning solution should be 0.0.
It is necessary to keep the flux concentration below 1% by weight, and in this embodiment, it is necessary to keep the flux concentration in the third cleaning tank 3, which is the final cleaning step, below the above concentration.

In order to keep the flux concentration in the cleaning liquid below a certain level, it is necessary to always ensure a certain amount of distillation with respect to the amount of flux introduced. The flow meter 26 is installed between the fourth liquid storage tank 25 and the third cleaning tank 3 for this purpose, and when the flow rate is below a certain level, an alarm is issued and the device is stopped.

FIG. 1 shows the structure of a flux concentration meter 27 for monitoring the flux concentration in the cleaning liquid in the third cleaning tank 3. The flux concentration meter 27 includes a light emitter 29a and a light emitter 29b for emitting light having a wavelength in a characteristic region.
, a cell 30a, a cell 30b, a cell 30c for pooling the cleaning liquid in order to pass this light through the cleaning liquid of each status, a photometer 31a and a light intensity for detecting the amount of light that has passed through the cleaning liquid in the cell. A total of 31b, a control unit 32 for determining and controlling information from these two photometers, and a micropump (not shown) for circulating cleaning liquid;
Cell 30a and photometer 31a correspond to cell 30a, and cell 30b corresponds to light emitter 29b.

A cell 30c and a photometer 31b are installed at corresponding positions.

In FIG. 1, solid lines with arrows indicate the flow of cleaning liquid, thick arrows indicate the flow of light, and broken lines with arrows indicate the flow of control information.

Next, the functions of the flux concentration meter 27 of this embodiment will be explained using FIG. 1, FIG. 2, and FIG. 3.

In general, substances have an inherent property of absorbing light of a specific wavelength. A clean cleaning liquid that has been distilled and stored in the fourth liquid storage tank 25 flows in the cell 30a, and the light generated by the first light emitter 29a passes through this liquid and is detected by the photometer 31a. Figure 2 shows the transmittance characteristics of light input to the photometer 31a in this way.
, a2. Absorption peculiar to the liquid passing through this cell occurs at a wavelength of a3. The liquid flowing through this cell is a distilled liquid, and no flux is mixed in. Al, a2. a
The absorption characteristics of No. 3 are considered to be due to the characteristics of the cleaning liquid and the decomposition inhibitor added to the cleaning liquid.

On the other hand, the light generated by the first light emitter 29b passes through a cell 30b in which the same liquid as the cell 30a flows, and a cell 30c in which a cleaning liquid mixed with some flux from the third cleaning tank 3, which is the final cleaning tank, flows and is then passed through the photometer. 31b. At this time, the absorption characteristics of the distilled cleaning liquid are as shown in FIG. 2, al, a2. In addition to a3, third cleaning tank 3
Characteristics bl and b2 corresponding to the concentration of the flux, that is, the characteristics possessed by the cleaning liquid are added. In the unit control 32, when the above-mentioned transmission characteristic is removed, the area indicated by diagonal lines in FIG. 3 is detected as an absorption characteristic peculiar to the flux, and the magnitude of this characteristic value is measured.

The flux concentration in the cleaning solution can be monitored.

Generally, a few percent of a decomposition inhibitor is mixed into a cleaning solution in order to prevent the cleaning solution from decomposing and turning into acids, etc. However, this decomposition inhibitor is used to prevent the cleaning solution from being repeatedly distilled and remanufactured. The concentration changes due to chemical changes. On the other hand, these decomposition inhibitors also have unique light absorption characteristics, and therefore, the influence of changes in the concentration of such decomposition inhibitors is extremely important in order to accurately detect flux concentrations of about 0.01%. Become a factor.

This flux concentration meter 27 makes it possible to separate the absorption characteristics of the decomposition inhibitor and the flux to be monitored.For this reason, the cleaning solution for comparison is not the new solution, but the cleaning tank to be monitored (in this example, the third The above-described error can be minimized by using a distilled cleaning liquid that has the same decomposition level as the cleaning liquid in the cleaning tank 3) and the decomposition inhibitor.

〔Effect of the invention〕

According to the present invention, a flux concentration meter that can constantly monitor and manage the flux concentration is obtained, so there is an effect that the cleaning liquid can always be kept clean.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a flux densitometer showing an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing the relationship between the wavelength of light obtained in the flux densitometer and the transmittance, and FIG. The figure is a sectional view of a cleaning device (example) related to the present invention.
This figure is a flow diagram of the cleaning liquid flowing through the cleaning apparatus shown in FIG. 1, and FIG. 6 is a diagram showing the relationship between the flux concentration in the cleaning liquid and the contact failure rate. 27...-Flux concentration meter 29a, 29b...=Light emitter 30a, 30b, 30c-Cell 31a
, 31b, - Photometer 32... Control unit 1st opening 2 jumping 3 closing 3oo tooo 7so. Placement number η basket〕man + flash 6 mouth, 1. It (V amount%)

Claims (1)

[Claims] A cleaning device having a cleaning tank for cleaning an object to be cleaned with flux attached thereto with a cleaning liquid, and a distillation machine for inputting the cleaning liquid contaminated by the cleaning through at least one of the cleaning tanks and outputting the clean cleaning liquid, first and second irradiation means that irradiate light having a wavelength in a specific region;
at least one first container having a transparent portion for capturing a sample of the clean cleaning solution; and a second container having a transparent portion for capturing a sample of contaminated cleaning solution after passing through any of the cleaning tanks. a first photometer for detecting the amount of light emitted by the first irradiation means after passing through the first container; and a second irradiation device after passing through the first container and the second container. a second device for detecting the amount of light emitted by the means;
the transmittance of the light detected by the first photometer and the second photometer.
1. A cleaning device comprising a flux densitometer that compares the transmittance of light detected by the photometer and determines the transmittance of the flux as a result.