JPH06315662A - Liquid coating device - Google Patents

Abstract

PURPOSE:To surely detect the residual quantity of a liquid difficult to confirm from the outside of a vessel by providing a photosensor to detect the height of the liquid level 'at the cap of the vessel in a liquid coating device having the vessel, in which the high viscous liquid reflecting light in a specific ratio is housed, and for dropping the liquid from the vessel by adequate quantity. CONSTITUTION:In the liquid coating device 8, having the vessel 2 housing the high viscous liquid 3 reflecting the light LA1 in the specific ratio and for dropping the liquid 3 from the vessel 2 by the adequate quantity, the photosensor 9 to detect the height of the liquid level 11 of the liquid 3 is attached at the cap 10 of the vessel 2. As a result, the residual quantity of the liquid (e.g. silver paste) easily sticking to the inside wall of the vessel and difficult to confirm the residual quantity from the outside of the vessel due to reflecting light is stably and surely detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid coating apparatus, and is suitable for application to, for example, a liquid coating apparatus having a measuring section for detecting the remaining amount of adhesive dropped on an integrated circuit lead frame.

[0002]

2. Description of the Related Art Conventionally, an adhesive called a silver paste has been used in a die bonding apparatus for adhering an integrated circuit chip to a lead frame, and an apparatus for dropping the silver paste having the structure shown in FIG. 2 has been used. There is.

In FIG. 2, reference numeral 1 denotes a silver paste dropping device as a whole, and a silver paste 3 is contained in a syringe 2. The silver paste dropping device 1 supplies compressed air 6 through an air hose 5 above the cap 4 attached to the syringe 2. As a result, the silver paste 3 is pushed down according to the pressure of the compressed air 6 and dropped from the nozzle 7 onto each lead frame (not shown).

[0004]

In the silver paste dropping device 1, the amount of the silver paste 3 that can be dropped in a series of bonding steps is limited by the volume of the syringe 2. Therefore, it is necessary to detect the remaining amount of the silver paste 3 in the syringe 2 and replace the syringe 2 with a new syringe 2 filled with the silver paste 3 before a defective adhesive product is generated due to the lack or lack of the silver paste 3. is there.

However, since the silver paste 3 has a high viscosity, the silver paste 3 is likely to remain attached to the inner wall surface of the syringe 2 and has a low transparency. Therefore, it is very difficult to visually confirm the remaining amount of the silver paste 3 from the outside. Have difficulty. Therefore, the cap 4 was removed and the remaining amount of the silver paste 3 was confirmed from above the syringe 2.

In this confirmation method, it is necessary to temporarily stop the die bonder in operation for the confirmation work, and there is a problem that the bonding work is interrupted several times before the replacement of one syringe 2. . Further, there is a problem that a defective product may be produced by continuing the bonding work with the die bonding apparatus while the silver paste 3 is insufficient or lacking due to a delay in residual amount confirmation or an error in visual measurement.

Also, the silver paste 3 is used without removing the cap 4.
It is conceivable to place the float on the silver paste 3 in order to detect the remaining amount of the above from the outside of the syringe 2. However, in the experiment, it was difficult to accurately detect the remaining amount of the silver paste 3 due to sinking of the float, adhesion of the silver paste 3 to the float, and the like.

The present invention has been made in consideration of the above points, and is capable of stably and reliably detecting the remaining amount of liquid which is easily attached to the inner wall of the container and is difficult to confirm with the naked eye from outside the container. Is to propose.

[0009]

In order to solve such a problem, the present invention has a container 2 in which a liquid 3 having a high viscosity and reflecting the light LA1 at a predetermined rate is stored. In the liquid application device 8 that drops an appropriate amount, an optical sensor 9 that detects the height of the liquid surface of the liquid 3 is attached to the lid 10 of the container 2.

[0010]

By measuring the height of the liquid surface 11 of the liquid 3 in the container 2 directly and in a non-contact manner with the optical sensor 9, the light LA1 is obtained.
The state of the liquid surface 11 that reflects the light is not disturbed, and the remaining amount of the liquid 3 can be detected stably and reliably.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 2 are designated by the same reference numerals, numeral 8 indicates a silver paste dropping device as a whole, and a cap 10 having a fiber sensor 9 in place of the cap 4 of the silver paste dropping device 1. Is attached to the upper portion of the syringe 2 so as to detect the remaining amount of the silver paste 3.

The syringe 2 is made of a semi-transparent hard synthetic resin material so that the rough height of the liquid surface 11 can be visually confirmed from the outside of the syringe 2 only when the silver paste 3 is filled. ing. The syringe 2 has a long cylindrical shape with a large diameter of about 15 mm and a nozzle with a predetermined shape corresponding to the shape of the lead frame at the lower end of the bottom where a round outlet is formed and a thin outlet is formed. 7 is attached.

An annular flange 2A is formed along the opening at the opening on the upper end side of the syringe 2. Also flange 2
A is provided with a notch at a position opposed to 180 ° so as to reach almost the outer peripheral surface of the syringe 2 and open at about 90 °.

The cap 10 is made of a semi-transparent hard synthetic resin material, and has a circular ceiling portion 1 continuous with the upper end of the cylindrical portion 10A.
A fiber sensor 9 is attached to 0B. The edge of the lower end of the cylindrical portion 10A is formed into a smooth flat surface and serves as a joint surface for the syringe 2.

An annular flange 10C having a U-shaped cross section is formed on the peripheral portion of the joint surface of the cap 10. In addition, the cylindrical portion 10 is provided at a position opposite to the flange 10C by 180 °.
A notched portion is provided so as to reach the vicinity of the outer peripheral surface of A and open at about 90 °. The flange 10C is configured to sandwich the flange 2A on the inner side surface.

When the cap 10 is attached to the syringe 2, the flange 2A and the flange 10C are combined with each other in the notches and the joint surfaces are brought into contact with each other.
Further, the cap 10 is about 90 mm larger than the syringe 2 so that the folded portion of the flange 10C sandwiches the flange 2A.
Rotated while sliding.

When the cap 10 is locked to the syringe 2 in this manner, the joint surface is brought into close contact with the elastic force of the joint surface itself, and the airtightness of the cap 10 and the syringe 2 is easily maintained. .

One end of an L-shaped joint 12 for supplying compressed air is fixed to the side surface of the cylindrical portion 10A with a screw.
The compressed air 6 is blown out toward the fiber sensor 9 from the blowout hole of this joint. A detachable base 13 is attached to the tip of the air hose 5, and this is connected to the other end of the joint 12.

The fiber sensor 9 has a sensor head 9A having a diameter of about 3 mm connected to a liquid level detecting device (not shown) via a fiber cable 14, and has a length of about 4 mm. The end portion 9B is oriented in the vertical direction, and is attached to the center of the ceiling portion 10B of the cap 10 by the screw portion 9C. The transmission / reception end portion 9B is composed of an injection fiber and a light reception fiber having a diameter of about 0.3 mm, and a thin stainless steel tube for accommodating the two fibers adjacent to each other.

Fiber cable 1 from the liquid level detector
The emission light LA1 given via 4 is emitted from the emission fiber to approximately the center of the liquid surface 11 of the silver paste 3. Further, the reflected light LA2 obtained by reflecting and scattering the emitted light LA1 on the liquid surface 11 is diffused according to the distance, so that the light amount is attenuated and is received by the light receiving fiber, and is received by the fiber cable 14 and the liquid surface. Given to the height sensing device.

As a result, the liquid level detector detects the reflected light L.
The light amount of A2 is measured, and when the light amount reaches a predetermined value, an alarm is generated by detecting that the distance from the tip of the transmission / reception end portion 9B to the center of the liquid surface 11 has reached a predetermined set value, It is designed to stop the die bond machine.

Incidentally, the silver paste 3 is in the form of an off-white mud in which silver fine particles are uniformly mixed in a binder of epoxy resin at room temperature, has a high reflectance for the emitted light LA1, and its liquid surface 11 is silver. The emitted light LA1 is scattered to some extent by forming minute unevenness due to the fine particles.

Further, the silver paste 3 has a liquid level 11 from the state in which the syringe 2 is filled to the level A at the limit of use.
Is almost flat, but the silver paste 3 is dropped and the liquid level 1
As 1 drops, a slight recess is generated in the center of the liquid surface 11.

In the above structure, first, the liquid level detector is adjusted so that an alarm is generated when the silver paste 3 decreases and the liquid level 11 reaches level A. When replacing with a new syringe 2, the cap 10 with the air hose 5 still attached is attached to the syringe 2.
At this time, the compressed air 6 is blown from the outlet of the joint 12 onto the fiber sensor 9, which prevents the splash of the silver paste 3 from adhering to the fiber sensor 9.

When the liquid level 11 is, for example, level B higher than level A, the distance from the tip of the transmitting / receiving end 9B to the liquid level 11 is short. Therefore, the light amount of the reflected light LA2 is large, and the liquid surface height detection device determines that the liquid surface 11 has not reached the level A and does not generate an alarm.

The compressed air 6 is 0.1 to 0.2 times the silver paste 3.
Press down with [kg / cm ² ] to drop. At this time, since the silver paste 3 has a high viscosity, the silver paste 3 remains attached to the inner wall of the syringe 2 and largely blocks the light coming from the outside of the syringe 2. This largely suppresses the influence of external light on the reflected light LA2.

As the silver paste 3 is consumed and the liquid surface 11 descends, the light amount of the reflected light LA2 decreases as the distance from the tip of the transmitting / receiving end 9B to the liquid surface 11 increases. As a result, when the liquid surface 11 reaches the level A, the light quantity of the reflected light LA2 becomes a predetermined set value. Therefore, the liquid level detector
An alarm is generated by detecting that the remaining amount of the silver paste 3 is insufficient, and the die bond device is stopped.

According to the above construction, since the height of the liquid surface 11 is directly measured by the fiber sensor 9 in a non-contact manner, the state of the liquid surface 11 is not disturbed and the silver is stable and reliable. The remaining amount of the paste 3 can be detected. Further, it is possible to prevent the generation of defective adhesion products due to lack or deficiency of the silver paste 3.

Furthermore, since the silver paste 3 can be used up to the minimum amount, the silver paste 3 is not wasted. Further, the work process for confirming the remaining amount of the silver paste 3 becomes unnecessary.

In the above-described embodiment, the fiber sensor 9 for detecting the amount of light to measure the distance is used. However, the present invention is not limited to this, and instead of the fiber sensor 9, the distance is measured by a phase shift. It can also be applied to the case of using a laser sensor.

In the above embodiment, the case where the fiber sensor 9 provided with the emitting fiber and the light receiving fiber is used is described, but the present invention is not limited to this, and one fiber can be used for both emitting and receiving light. The present invention can also be applied to the case of using an optical sensor, a multi-core optical sensor, a coaxial dual optical sensor, or the like.

Further, in the above-mentioned embodiment, the case where the fiber sensor 9 in which the emitting fiber and the light receiving fiber are provided adjacent to each other is used is described, but the present invention is not limited to this, and the emitting part and the light receiving part are not provided. The present invention can also be applied to the case where an optical sensor provided at a predetermined distance is used for triangulation.

Further, in the above embodiment, the liquid surface 11
The case where the remaining amount is detected by measuring the height of the liquid paste has been described, but the present invention is not limited to this, and the dropping speed of the silver paste 3 is detected by measuring the height of the liquid surface 11. It can also be applied when doing.

Further, in the above-mentioned embodiment, the case where the height of the liquid surface 11 of the silver paste 3 is measured has been described, but the present invention is not limited to this, and the light easily adheres to the inner wall of the container and the light is irradiated at a predetermined rate. It can be widely applied to the measurement of the height and the remaining amount of the liquid surface 11 of the liquid that is reflected or scattered by.

Further, in the above-described embodiment, the case where the syringe 2 and the cap 10 are made of a translucent material has been described, but the present invention is not limited to this, and the syringe 2 and the cap 10 are made of an opaque material and absorb light. It can also be applied when the material is made of a high material.

Further, in the above-mentioned embodiment, the case where the predetermined amount of the silver paste 3 is detected to generate the alarm has been described, but the present invention is not limited to this, and light such as a lamp may be used instead of the alarm. You may use.

[0038]

As described above, according to the present invention, since the height of the liquid surface is directly measured in a non-contact manner by an optical sensor, the liquid easily adheres to the inner wall of the container and reflects light at a predetermined rate. It is possible to realize a liquid application device that can stably and reliably detect the remaining amount of the liquid that remains without disturbing the state of the liquid surface.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an embodiment of a liquid applying apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing an overall configuration of a conventional example.

[Explanation of symbols]

1, 8 ... Silver paste dropping device, 2 ... Syringe, 3 ...
... Silver paste, 4,10 ... Cap, 5 ... Air hose, 6 ... Compressed air, 7 ... Nozzle, 9 ... Fiber sensor, 11 ... Liquid level, 12 ... Joint, 13 ... Base,
14 ... Fiber cable, LA1 ... Emitted light, LA2
……reflected light.

Claims (3)

[Claims] 1. A liquid application apparatus having a container containing a liquid having a high viscosity and reflecting light at a predetermined rate, and dropping an appropriate amount of the liquid from the container, wherein a liquid of the liquid is placed on a lid of the container. A liquid application device, wherein an optical sensor for detecting the height of a surface is attached. 2. The liquid coating apparatus according to claim 1, wherein the optical sensor is an optical fiber sensor or a laser sensor. 3. The lid has a compressed air supply hole for adjusting a dropping amount of the liquid on a side wall of the lid, and blows the compressed air to the optical sensor. The liquid application device according to claim 2.