KR20030050715A - Barrel plating apparatus and method - Google Patents

Abstract

PURPOSE: A barrel plating apparatus and a barrel plating method are provided to greatly reduce twin chip of any types of small chip component by installing an ultrasonic generator at barrel plating tank and using pulse power supply so that ultrasonic waves and pulse current are periodically alternately generated during barrel plating. CONSTITUTION: The barrel plating apparatus comprises a plating tank(110) in which electrolyte is stored; a barrel main body(130) rotationally arranged inside the plating tank; anodes(122a,122b) arranged inside the plating tank and consisted of the same material as ions contained in the electrolyte; power supply part(120) for supplying pulse current through the cathode connected between the anodes and barrel main body; an ultrasonic wave generation part(140) for supplying certain ultrasonic waves into the plating tank; and a control part(150) for electrically controlling the power supply part and ultrasonic wave generation part so that pulse current and ultrasonic waves are periodically alternately generated, wherein the ultrasonic wave generation part generates ultrasonic waves having a frequency of about 20 to 60 kHz, the periodically alternately generated pulse current and ultrasonic waves are controlled to on-time that is at least longer than one revolution time of the barrel main body in the control part, and the control part is controlled so that both the ultrasonic waves and pulse current are off for a certain period of time when the pulse current and ultrasonic waves are alternately generated.

Description

Barrel Plating Apparatus and Plating Method {BARREL PLATING APPARATUS AND METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrel plating apparatus, and more particularly, to a barrel plating apparatus and a plating method that can effectively prevent chip sticking by periodically applying an ultrasonic wave and a pulse current.

In general, small chip components such as chip resistors, multilayer ceramic chips, chip inductors, etc. are mounted on a printed circuit board by soldering external electrodes. The external electrode of such a small chip component is formed of silver paste or copper paste, and after the nickel plating is applied to the external electrode to improve soldering of the chip component to a printed circuit board, tin (Sn) or tin-lead (Sn-Pb) is used. ) Is plated. The barrel plating method is mainly applied to this plating process. The barrel plating method can be performed by selecting from a rotating barrel, a vibrating barrel, or a high-speed rotating plating apparatus according to the size, shape, etc. of the chip component.

1 is a schematic view of one embodiment of a conventional barrel plating apparatus. Referring to FIG. 1, the barrel plating apparatus includes a plating bath 10, a power supply device 20, and a barrel body 30. The power supply device 20 is a positive electrode (22a, 22b) located outside the barrel body 30 in the plating tank 10, and the negative electrode is connected to the inside of the barrel body 30, the plating body in the barrel Supply DC current to In addition, a metal dummy ball (not shown) is added at an appropriate ratio to smoothly energize the electrode part of the chip part, and a ceramic ball or a large diameter metal can be better mixed with the chip part and the dummy ball. Put the ball in.

The chip part 50 to be plated on the barrel plating apparatus has a large outer shape and sharp edges as shown in FIG. 2A. Accordingly, in the process of plating the external electrode 51 of the chip component 50, as shown in FIG. 2B, the external electrodes 61 and 71 of the chip components 60 and 70 are plated with each other. . This is called a twin chip. When the chip sticking phenomenon occurs, there is insufficient plating thickness on the external electrode on the side, which causes defects and decreases the reliability of parts. In severe cases, the chip parts cannot be used because they are not separated. have.

In order to solve this problem, conventionally, when plating flat and angled chip parts, a number of variables such as the type of barrel, the size and mixing ratio of the dummy ball, and the degree of stirring of the plating solution have been used. However, variables such as the size and the input amount of the chip parts are frequently generated for each process, and it is not easy to find an optimization condition for chip sticking in the conventional method. In addition, since the degree of chipping defects also changes depending on the characteristics of the plating liquid, there is a problem that a great restriction is placed even when the plating liquid is selected in consideration of solderability, workability, liquid stability, and safety.

Therefore, there is a need in the art for a new barrel plating apparatus and a plating method thereof for preventing chip sticking.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to install an ultrasonic wave generator in a barrel plating bath and use pulse power to periodically cross ultrasonic waves and pulse currents during barrel plating, thereby chipping small rectangular chip components. It is to provide a barrel plating apparatus that can greatly reduce the defect.

It is still another object of the present invention to provide a barrel plating method for periodically generating ultrasonic waves and pulse currents during barrel plating in a barrel plating bath.

1 is a schematic view showing a conventional barrel plating apparatus.

2A and 2B are schematic diagrams showing rectangular chip parts and chip sticking phenomenon.

3 is a schematic view showing a barrel plating apparatus according to an embodiment of the present invention.

4 is a graph showing the generation period of the ultrasonic wave and the pulse current.

<Code Description of Main Parts of Drawing>

110: plating bath 120: power supply

130: barrel body 140: ultrasonic generator

150: control unit

In order to achieve the above object, the present invention, the plating tank in which the electrolyte solution is stored, the barrel body is configured to be rotatable in the plating tank, and the anode made of the same material as the ions disposed in the plating bath and contained in the electrolyte solution; A power supply for supplying a pulse current through the cathode connected to the anode and the barrel body, an ultrasonic generator for supplying predetermined ultrasonic waves in the plating bath, and a pulse current and ultrasonic waves to be periodically generated Provided is a barrel plating device comprising a power supply and a control unit for electrically controlling the ultrasonic generator.

In a preferred embodiment of the present invention, the frequency of the ultrasonic waves generated by the ultrasonic wave generator is in the range of about 20 Hz to about 60 Hz.

In particular, the control unit preferably controls each of the pulse current and the ultrasonic wave generated by the periodic crossing at least on-time longer than one rotation time of the barrel body, and when the pulse current and the ultrasonic wave cross-over. During the predetermined time, both the ultrasonic wave and the pulse current are turned off to secure the delay time, thereby restoring the ion concentration distribution of the plating interface to the initial condition.

Furthermore, in the present invention, it is preferable to adjust the pulse current generation time per cycle to about 1 minute or more and 10 minutes or less, and to adjust the ultrasonic generation time per cycle to about 20 seconds to 120 seconds or less.

The present invention also provides a novel barrel plating method. That is, in the method of plating a chip component by using a barrel plating apparatus provided with a plating body and a rotatable barrel body which provides a plating material in a plating tank in which an electrolyte is stored, the method of disposing a chip component to be plated in the plating tank is performed. A second step of supplying a pulse current for a first time using the barrel body and the plated body as two poles, and stopping the pulse current after the first time has elapsed and applying a predetermined ultrasonic wave to the plating bath. It is also possible to provide a barrel plating method comprising a third step of generating for two hours and a fourth step of sequentially repeating the second step and the third step at least once.

Hereinafter, embodiments and principles of the present invention will be described in detail with reference to the drawings.

3 is a schematic diagram of a barrel plating apparatus using the ultrasonic wave generator 140 and the pulse power supply 120 according to the present invention. Referring to FIG. 3, the barrel plating apparatus includes a plating bath 110, a barrel body 130, anodes 122a and 122b as plating bodies, a power supply unit 120, an ultrasonic wave generator 140, and a controller 150. It consists of.

An electrolyte is stored in the plating bath 110, and the barrel body 130, the anodes 122a and 122b, and the ultrasonic wave generator 140 are disposed. The power supply unit 120 supplies a pulse current for performing plating using the anodes 122a and 122b and the cathode inside the barrel body 130 as two poles. In addition, in the present invention, the control unit 150 for controlling the power supply unit 120 and the ultrasonic wave generator 140 is provided so that the pulse current and the ultrasonic wave is periodically generated.

As such, the barrel plating apparatus of the present invention is configured to periodically generate pulse current and ultrasonic waves in the plating bath in which plating is in progress. The pulse current ionizes the anodes 122a and 122b in the electrolyte to form a plating layer on the external electrode of the chip component inside the barrel body connected to the cathode. In addition, the controller 150 stops the pulse current supply after a predetermined time elapses, and then operates the ultrasonic wave generator 110 to supply the predetermined ultrasonic waves into the plating bath 110. These ultrasonic waves serve to separate the chip components attached in the plating process by vibration. By repeatedly performing such an operation through the controller 150, the plating process may be performed while preventing the attachment of the chip component.

A feature of the present invention is that it is possible to form a high quality plating layer while preventing chip sticking by periodically supplying ultrasonic waves and pulse power in a barrel plating process of chip components.

In the state of the art, with mutual interference and reinforcement between sound waves reflected from an object to which ultrasonic waves having a frequency of less than 200 Hz are plated, the generator generates cavities on the surface of the platen by standing waves, which causes the cavity to rupture. It was only known that the surface cleaning effect, the stirring effect, and the like occurred. After experiments and studies on this, the inventors found that the use of ultrasonic waves prevents the plated bodies, in particular, flat surfaces of small chip parts from being plated together when they meet each other due to their vibrational energy.

However, the ultrasonic waves below 200 μs generate stresses in the plating layer, which may affect the nucleation process of the plating layer, thereby causing a problem of forming a dense structure. In order to solve this problem, the present inventors have been able to suggest that, through repeated experiments, the plating and the chipping phenomenon can be prevented at the same time by performing a smooth plating by crossing the period of the ultrasonic wave and the pulse current. In other words, if the ultrasonic wave is not applied during the period of applying the pulse current, the plating process occurs for a short time without the influence of the ultrasonic wave, and the next cycle, the ultrasonic wave is applied and the current is cut off to forcibly separate the chips attached during the plating process. . By devising the barrel plating apparatus of FIG. 3 implemented on the same principle, it is possible to greatly reduce chip adhesion defects and obtain a dense plating layer.

4 is a graph showing the pulse current and the ultrasonic operation of the barrel plating apparatus according to the present invention.

First, the plating process is started by supplying a pulse current for a first time t1-t2. When the first time t2 with respect to the pulse current has elapsed, the pulse current supply is stopped and ultrasonic waves are generated to separate the stuck chip with vibration. When the second time t3-t4 for the ultrasonic supply elapses, the generation of the ultrasonic wave is stopped, and the pulse current supply is also kept off for a predetermined time t2-t3. As such, securing a delay time (t2-t3) between the ultrasonic wave and the pulse current is for restoring the ion concentration distribution at the plating interface to the initial condition after the ultrasonic wave is stopped and before the pulse current is applied. to be. This delay time (t2-t3, t4-t5) is preferably between 1 second and 20 seconds. By repeating the above-described periodic cross supply of pulse current and ultrasonic waves until the plating process is completed, a chip component having an excellent plating layer which prevents chipping phenomenon can be obtained. Subsequently, the pulse current is applied again for the first time t3-t4, and the ultrasonic wave is generated again after a predetermined time t4-t5 interval until the plating is completed.

Here, the pulse current supply time and the ultrasonic generation time is preferably made longer than the time required for one revolution of the barrel body used. This is because at least one rotation time of the barrel body can be supplied to give a uniform effect on all chips. In addition, the ultrasonic generation time is preferably shorter than the time that the pulse current is applied.

More preferably, the pulse current supply time is about 1 to 10 minutes. When the pulse current is supplied for less than 1 minute, it is difficult to form a sufficient plating layer, and when supplied for 10 minutes or more, chip sticking occurs in a plurality of chip parts, and the degree of adhesion is firm, resulting in difficulty in separation. On the other hand, the ultrasonic generation time is preferably in the range of 20 seconds to 120 seconds. This is because if the ultrasonic generation time is 20 seconds or less, sufficient chip part separation effect cannot be obtained, and if it is 120 seconds or more, oxidation may occur in the plating layer generated in the chip part.

Furthermore, the frequency of the ultrasonic wave used in the present invention is preferably in the range of 20 Hz to 60 Hz. This is because a sufficient effect cannot be obtained at less than 20 μs, and material deformation may occur at a plating bath or a barrel body at 60 μs or more.

Hereinafter, an embodiment according to the present invention will be described.

As shown in Fig. 3, a barrel body was installed in a plating bath provided with an ultrasonic vibrator having a frequency of 27 kHz and 1 MHz. The square chip parts in which chip adhesion defects easily occur were plated for 60 minutes at 4.5 amps (A) at a temperature of 55 DEG C in a watt nickel bath.

The resultant was plated with tin (Sn) again. In this tin plating process, the chip sticking rate was evaluated by changing the ultrasonic and pulse current conditions. The chipping incidence rate was evaluated by the weight percentage of the total weight put into the chip | tip generating chip | tip. Table 1 shows the chip sticking rate according to the ultrasonic wave and pulse current conditions.

Psalter Frequency of ultrasound Ultrasonic Generation Time Current supply time Chip adhesion rate (%) One* 27㎑ 0 continuity 17 2 40 seconds 10 minutes 2 3 40 seconds 5 minutes 0.7 4 40 seconds 2 minutes 0.3 5 * continuity continuity 0.2 6 1 MHz 40 seconds 2 minutes 0.1 * Is outside the scope of the present invention.

As shown in Table 1, when ultrasonic waves were not applied, defects occurred very severely at 17%. It can be seen that as the pulse current supply time, i.e., the cycle of applying the ultrasonic wave, becomes faster at the frequency of 27 Hz, the chipping defect is significantly reduced.

In particular, the chip adhesion decreased by 0.3% when the supply time of the pulse current was 2 minutes. If the ultrasonic wave is applied continuously, the chip adhesion is minimized to 0.2%, but it is difficult to apply because there is a problem such as cold solder defect in the soldering process because the plating is very rough and not dense.

In addition, when the ultrasonic frequency was set to 1 MHz, the chip adhesion rate was 0.1%, which is more improved than that at 27 kHz. However, since the energy of the ultrasonic wave is large, the problem of deforming the material of the barrel body arises. Improvements in barrel materials are needed. When the material of the barrel body is improved, the ultrasonic wave effect is generated in such a way that the scattering is very high at 400 kHz or higher, so that standing waves are not formed and energy is directly transmitted to the plating body. Unlike less than 200kHz, since no shock wave is generated, it does not cause stress such as plastic deformation in the plating layer. Therefore, the same effect can be obtained even under the condition corresponding to the specimen 5 * without periodically crossing.

The present invention described above is not limited by the above-described embodiment and the accompanying drawings, but by the appended claims. Therefore, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible without departing from the technical spirit of the present invention described in the claims.

As described above, by installing the ultrasonic generator in the barrel plating bath and using a pulse power source, the chipping defect of the small-sized chip component of the square can be greatly reduced by periodically crossing the ultrasonic wave and the pulse current during barrel plating.

Claims (12)

Plating bath in which the electrolyte is stored; A barrel body disposed in the plating bath and configured to be rotatable; An anode disposed in the plating bath and made of the same material as ions contained in the electrolyte solution; A power supply for supplying a pulse current through the cathode connected to the anode and the barrel body; An ultrasonic wave generator for supplying predetermined ultrasonic waves to the plating bath; And Barrel plating device comprising a control unit for electrically controlling the power supply and the ultrasonic wave generator so that the pulse current and the ultrasonic wave is generated periodically cross. The method of claim 1, And the ultrasonic generator generates a ultrasonic wave having a frequency of about 20 Hz or more and about 60 Hz or less. The method of claim 1, The control unit is a barrel plating apparatus, characterized in that for each of the pulse current and the ultrasonic wave generated periodically intersecting at least on time longer than one rotation time of the barrel body. The method of claim 1, The control unit is a barrel plating apparatus, characterized in that for controlling the pulse current and the ultrasonic wave is generated so that both the ultrasonic wave and the pulse current is turned off for a predetermined time. The method of claim 1, The control unit is a barrel plating apparatus, characterized in that for controlling the pulse current generation time per cycle from about 1 minute to less than 10 minutes. The method of claim 1, The control unit is a barrel plating apparatus, characterized in that for adjusting the ultrasonic generation time per cycle from about 20 seconds to 120 seconds or less. A method of plating a chip component by using a barrel plating apparatus having an anode and a rotatable barrel body for providing a plating material in a plating tank in which an electrolyte is stored, Placing a chip component to be plated in the plating bath; A second step of supplying a pulse current for a first time using two cathodes of the cathode and the anode inside the barrel body; A third step of stopping the pulse current after the elapse of the first time and generating a predetermined ultrasonic wave in the plating bath for a second time; And Barrel plating method comprising the step of repeating the second step and the third step at least one time in sequence. The method of claim 7, wherein And the frequency of the predetermined ultrasonic wave is in the range of about 20 kHz to about 60 kHz. The method of claim 7, wherein And a first time at which the pulse current is generated and a second time at which the ultrasonic wave is generated are at least one rotation time of the barrel body, respectively. The method of claim 7, wherein And both the ultrasonic wave and the pulse current are turned off for a predetermined time between the first time at which the pulse current is generated and the second time at which the ultrasonic wave is generated. The method of claim 7, wherein Barrel plating method characterized in that the first time for generating the pulse current is about 1 minute or more and 10 minutes or less. The method of claim 7, wherein And the second time period during which the ultrasonic waves are generated is about 20 seconds to 120 seconds.