JPH0763687B2 - Article cleaning method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and apparatus for cleaning articles, and more particularly to a method and apparatus for cleaning articles having fine gaps and holes such as IC substrates.

[Problems to be solved by the invention]

Ultrasonic cleaning is generally used for cleaning precision processed products such as substrates having fine gaps or recesses.

Ultrasonic cleaning can remove stains adhering to the smooth surface of an article relatively easily, but stains adhering to fine gaps or small holes become soft-fitting, but are not completely removed. Therefore, the yield of the product is poor, and
There is a problem in that mechanical post-processing such as removal is troublesome. Further, the frequency of the conventional ultrasonic device using the oscillator is 28 kHz at most, which is insufficient in itself.

The present invention has been made to solve this problem,
It is an object of the present invention to provide a novel cleaning method capable of easily and completely removing dirt in a gap or a small hole of a substrate in a cleaning tank, and an apparatus for carrying out this method.

[Means for solving problems]

In order to achieve the above object, the present invention is to circulate a cleaning liquid in a cleaning tank containing an object to be cleaned at a predetermined flow pressure and at the same time, introduce a cleaning liquid in a circulation system into air to perform gas-liquid mixing by a mixing device. , A jet flow containing fine bubbles and ultrasonic waves are generated in the cleaning tank, whereby the object to be cleaned in the tank is subjected to primary cleaning by ultrasonic cleaning and friction cleaning, and then the cleaning tank is closed. Then, carbon dioxide is dissolved in the cleaning liquid while being pressed and mixed into the cleaning liquid through the mixing device of the circulation system, and then the cleaning tank is depressurized to cause the mixed gas in the cleaning liquid to diverge in a boiling state from the liquid to separate the gas in the tank. The object to be cleaned is subjected to the secondary cleaning by the vibration and the wave at the time of separation.

Example of Invention

 Embodiments of the present invention will be described with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a cleaning tank in which an object to be cleaned is put into a cleaning liquid inside for cleaning. The cleaning tank 1 is composed of a pressure-resistant container having a lid 2 that can be closed and opened, and a lid 2 is provided with a pressure reducing valve 3.

Here, the washing liquid refers to water or so-called general washing water in which water and a detergent are dissolved.

The cleaning tank 1 is provided with a channel 5 for circulating the cleaning liquid in the tank via the pump 4 at a predetermined pressure, and the pump discharge side pipe 5a of the circulation channel 5, preferably the cleaning tank 1
A mixing device 6, which will be described later, is arranged at the connection part to the.

An air supply means 7 is connected to the circulation flow path 5 from the outside to introduce air or a detergent together with air into the cleaning liquid in the flow path from the outside.

The air supply means 7 is provided with an ejector valve 7b for controlling the flow rate of air in the supply pipe 7a, and the pipe 7a is connected to the circulation passage 5
The mixing device 6 or the upstream side thereof is connected. In the illustrated embodiment, since the self-contained mixing device as shown in FIG. 4 is used as the mixing device 6, the supply pipe 7a is joined to the axis of the mixing device 6, but the air introduction position is shown in FIG. The structure is not limited to, for example, the circulation channel 5
The structure may be such that the supply pipe 7a is connected to the pipe 5a between the pump 4 and the mixing device 6 and air is press-fitted into the cleaning liquid in the flow path 5 by using an air compressor or the like, and cavitation occurs for a long time. Circulation flow path 5
An air supply pipe 7a may be connected to the pump suction side pipe 5b to suck air into the flow path.

Furthermore, the pipe between the pump 4 and the mixing device 6 in the circulation channel 5
A carbon dioxide supply device 8 that pressurizes carbon dioxide CO ₂ into the cleaning liquid in the flow channel from the outside is connected to 5a (pump discharge side pipe). In this CO ₂ supply device 8, the supply pipe 8b of the CO ₂ cylinder 8a is connected to the pipe 5a (pump discharge side pipe) between the pump 4 and the mixing device 6 of the cleaning liquid circulation flow path 5 or the mixing device 6. The regulator mechanism 8c can adjust the discharge pressure in advance.

In the illustrated embodiment, the CO ₂ supply pipe 8b is connected to the pipe 5a between the pump 4 and the mixing device 6, but instead, the pipe 8b is connected to the air supply pipe 7a via a switching valve, Carbon dioxide may be introduced into the shaft core of the self-contained mixing device 6.

It is desirable that the pressure of carbon dioxide is substantially equal to the net head of the pump 4 (total head minus pressure loss of piping and mixing device). For example, if the CO ₂ supply pressure is 4 kg / cm ² , the pump 4 head is (4 + ΔP ₁ +
ΔP ₂ ) kgf / cm ² (ΔP ₁ is the pressure loss of the pipe, ΔP ₂ is the pressure loss of the mixing device 6). This has the advantage that the supply of carbon dioxide is automatically stopped at the time when the pump head of the CO ₂ supply device 8 becomes substantially equal to the pump head. This also means that the supply of CO ₂ automatically stops when the CO ₂ in the cleaning liquid dissolves to the saturation value under the design temperature and pressure, which is extremely convenient for management.

The carbon dioxide CO ₂ supplied from the CO ₂ supply device 8 may be gas, liquid or solid.

Next, FIGS. 2 and 3 show specific examples of the mixing device 6 suitable for carrying out the present invention. The mixing device 6 shown in the drawing basically has a cylindrical mixing shape as shown in FIG. On the inner peripheral wall of the upstream side of the pipe 61, a current-changing guide vane for generating an internal fluid into an accelerated concentric-circle-shaped multilayer swirling flow having a negative pressure portion in the central portion.
62 is provided, and a large number of impact bodies 63 are fixedly mounted on the inner peripheral wall of the downstream side thereof, so that the multilayer swirling flow collides with the impact body 63 and is violently disturbed.

For this reason, the current-changing guide vane 62 intersects the chord side edges 65, 65 of the pair of split elliptical discs 64, 64, and bisects the chord side edges on the upstream side of the intersection in the mixing pipe 1 in the axial direction. The mixing pipe 6 is closed by a triangular partition plate 66, and the arc side edges 67, 67 of the pair of split ellipses 64, 64 are joined to the inner wall of the mixing pipe 61.
It is located inside 1.

Further, the collision body 63 preferably has an inverted frustum frustum portion 63b having a hemispherical portion 63a at the tip as shown in FIG. 3, so that the multilayer swirling flow flowing down in the mixing pipe collides with the collision body 63. Are arranged toward the axis of the mixing tube 61 in various positional relationships.

It is of course possible to attach the basic mixing apparatus of FIG. 2 to the cleaning liquid circulation circuit 5 of the present invention as it is and introduce air from the upstream side of the mixing apparatus 6, but preferably, as shown in FIGS. 1 and 4. Further, the tip of the supply pipe 7a of the air supply means 7 is penetrated through the current-changing guide vane 66 to be used as a self-contained mixing device. That is, in the case of such a configuration, since the tip end opening of the air supply pipe 7a faces the central negative pressure portion of the multilayer swirl flow formed downstream of the current-flow guide vane 66, the air of the air supply means 7 is supplied with a special supply. The cleaning liquid is sucked into the swirling flow of the cleaning liquid in a self-priming manner without requiring any feeding means. Next, the operation of the cleaning method and apparatus of the present invention will be described.

First, an article to be cleaned such as an IC substrate and a cleaning liquid are put in the cleaning tank 1.

Initially, by closing the supply pipe 8b of the CO ₂ supply device 8 and operating the pump 4 of the circulation circuit 5, the cleaning liquid in the tank 1 is circulated through the mixing device 6 in the circulation flow path 5 at a predetermined flow rate, and The ejector valve 7b of the supply means 7 is operated to introduce air into the cleaning liquid flow through the mixing device 6. (Add detergent if necessary). At this stage, the pressure reducing valve 3 or the lid 2 of the cleaning tank 1 may be closed or open.

The cleaning liquid in the circulation circuit 5 pumped by the pump 4 is mixed by the mixing device 6
The variable flow guide vanes 62 form a multi-layered swirling flow with accelerated concentric structures of different densities, and at the same time, swirling the swirling vortex with the air from the air supply device 7 sucked into the central negative pressure part of the swirling vortex And is shaken and agitated by colliding with the protrusion 63 in the process of flowing. As a result, ultrasonic waves are generated in the cleaning liquid, and the air introduced into the cleaning liquid is made into fine bubbles and jetted into the tank 1 together with the cleaning liquid. The ultrasonic waves and the jet flow perform ultrasonic cleaning and friction cleaning in the tank 1. Be seen.

In particular, since the mixing device of the present invention forms a low-pressure portion near the central shaft on the downstream side, it has the effect of lowering the saturated vapor pressure of the fluid by the shearing force due to the action of the pressure gradient, so that gas-liquid mixing is performed rapidly. .

The same applies when air is introduced from the upstream side of the flow guide vanes of the mixing device 6.

Open the ejector valve 7b of the air supply device 6 from "open" to "close"
The amount of introduced air, the amount of generated bubbles,
The bubble particle size as well as the frequency of the generated ultrasonic waves can be controlled. By the way, the frequency of the ultrasonic wave obtained from the present invention by adjusting the cleaning flow rate and the ejector valve and its adjustment range are approximately 16 to 40 kHz.

After the primary cleaning process by ultrasonic cleaning and friction cleaning, the ejector valve 7b of the air supply device 7 is closed, the decompression valve 3 of the cleaning tank 1 is closed and sealed, and then the valve 8c of the CO ₂ supply device 8 is closed. Open and press-fit carbon dioxide CO ₂ into the cleaning liquid in the flow path 5.

The carbon dioxide gas sent into the circulation channel 5 is forcibly stirred and mixed by the above-mentioned action of the mixing device 6 in the process of passing through the mixing device 6 together with the cleaning liquid, and becomes fine bubbles to be uniformly dispersed in the liquid, And, it dissolves up to almost the saturated value at the temperature and pressure at that time. Therefore, carbon dioxide having a substantially saturated value is dissolved in the liquid in the minute gaps or small holes of the article to be cleaned.

The CO ₂ supply device 8 has a regulator mechanism 8c in advance so that the discharge pressure thereof is substantially equal to the net head of the circulation pump.
Since the pressure in the cleaning tank 1 is adjusted to CO ₂
The supply of CO ₂ is automatically stopped when the pressure rises to around the regulated pressure of the supply device.

Next, the pressure reducing valve 3 provided on the upper lid 2 of the cleaning tank 1
open. Then, the carbon dioxide CO ₂ that was high-pressure encapsulated in the cleaning liquid with a large solubility rapidly vaporized as the pressure decreased to equilibrate with the solubility at the pressure outside the tank (for example, atmospheric pressure), and a large amount of small bubbles were formed. As a result, the liquid in every region of the cleaning tank 1 is boiled violently in a boiling state, and is diverged and separated. Thus, due to the vibration and frictional force of the gas and liquid generated when carbon dioxide gas is removed from the liquid, the soft deposits in the fine gaps and small holes of the article to be cleaned, that is, the deposits that could not be removed by ultrasonic cleaning, can be removed cleanly. Be done.

〔The invention's effect〕

As described above, the present invention can be applied to the ultrasonic cleaning and the friction cleaning.
While performing the second cleaning, the soft-adhesion deposits in the fine gaps that cannot be completely removed by the first cleaning are vibrated when carbon dioxide gas is emitted.
Since the secondary cleaning is performed by the wave and frictional force, the cleaning effect is remarkably improved, and the post-treatment is unnecessary. Moreover, these first
Since the second and second cleanings are continuously performed in the same cleaning tank, the operation and management are easy.

Further, in the present invention, since a high frequency of 40 kHz can be obtained, the ultrasonic cleaning itself can be dramatically improved,
A wide range of adjustment from 16 to 40kHz is possible just by operating the valve. Further, when used in the present invention, the device is not only excellent as an ultrasonic generator, but it is easy to uniformly mix and agitate gas and liquid, and has a high gas absorption effect, so that it can be used for both primary and secondary cleaning. And the cleaning action can be synergistically improved.

[Brief description of drawings]

FIG. 1 is a flow chart of the device of the present invention, FIG. 2 is a partially cutaway perspective view of the mixing device used in the present invention, FIG. 3 is an enlarged side view of a collision body of the mixing device, and FIG. 4 is of FIG. It is a longitudinal section of a mixing device in an example. 1 ... Washing tank, 3 ... Pressure reducing valve, 4 ... Pump, 5 ... Circulating flow path, 6 ... Mixing device, 7 ... Air supply device, 8 ...
CO ₂ supply device, 62 …… Current transformation guide vane, 63 …… Collision body.

Continuation of front page (56) Reference JP-A-57-65370 (JP, A) JP-A-62-191090 (JP, A) JP-A-61-278800 (JP, A) JP-A-61-8184 (JP , A) JP 61-78482 (JP, A) JP 60-125283 (JP, A) JP 54-155655 (JP, A) JP 60-125283 (JP, A) JP 54-147557 (JP, A) JP 49-31154 (JP, A) Actual 60-74099 (JP, U) Actual 59-36852 (JP, U) Actual 51-20367 (JP, A) U) Special public Sho 61-9600 (JP, B2) Special public 4-43712 (JP, B2) Actual public 49-16195 (JP, Y1) Actual public 46-32633 (JP, Y1) Actual public Sho 56 -27991 (JP, Y2) Showa 58-23383 (JP, Y2)

Claims (4)

[Claims] 1. A cleaning tank containing an object to be cleaned is circulated at a predetermined flow pressure, and at the same time, air is introduced into the cleaning solution in the circulation system to perform gas-liquid mixing by a mixing device, whereby A jet flow containing fine bubbles and ultrasonic waves are generated, whereby the object to be cleaned in the tank is subjected to the primary cleaning by ultrasonic cleaning and friction cleaning, and then the cleaning tank is closed to close the circulation system. Carbon dioxide CO ₂ is dissolved by pressurizing and mixing it into the cleaning liquid through the mixing device, and then the cleaning tank is depressurized to cause the mixed gas in the cleaning liquid to boil off from the liquid to the cleaning object in the tank. A method for cleaning an article, characterized in that a secondary cleaning is performed by vibration and waves at the time of separation. 2. A pressure-resistant cleaning tank 1 having a pressure reducing valve 3 and capable of being closed.
A cleaning liquid circulation flow path 5 for circulating the cleaning liquid in the cleaning tank 1 via a pump 4, a mixing device 6 arranged in a pump discharge side pipe 5a of the circulation flow path 5, and a mixing device 6 for the circulation flow path. Or connected to its upstream side,
An air supply means 7 for introducing air into the cleaning liquid in the flow path 5 and a CO ₂ supply device 8 connected to the mixing device 6 of the circulation flow path 5 or the upstream side thereof and introducing carbon dioxide into the cleaning liquid in the flow path 5. An article cleaning apparatus comprising: 3. The mixing device (6) has a mixing pipe (61) which intersects the chord side edges of a pair of split ellipses (64, 64) on the upstream side of the cylindrical mixing pipe (61) and between the chord side edges on the upstream side of the intersection. Is equipped with a current guide vane 62 closed by a triangular partition plate 66 that divides the
The article cleaning apparatus according to claim 2, wherein a large number of collision bodies 63 are provided on the inner peripheral wall of the mixing pipe on the downstream side of the guide vanes 62. 4. An article cleaning apparatus according to claim 3, further comprising a supply pipe 7a of the air supply apparatus 7 which is provided through the axis of the current-changing guide vane 62 of the mixing apparatus 6.