GB2306509A

GB2306509A - concentration control apparatus

Info

Publication number: GB2306509A
Application number: GB9622144A
Authority: GB
Inventors: Kil Nam Hwang; Keun Chang Cho
Original assignee: Anam S & T Co Ltd
Current assignee: Anam S & T Co Ltd
Priority date: 1995-10-27
Filing date: 1996-10-24
Publication date: 1997-05-07
Also published as: DE19645148A1; JPH09249996A; GB9622144D0; KR100201377B1; KR970023663A

Description

A.

2306509 CONCENTRATION CONTROL APPARATUS FOR MULTI-COMPONENT PLATING SOLUTION BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a concentration control apparatus for a plating solution composed of a variety of components, capable of always maintaining constant amounts and concentration ratios of the components, thereby not only improving the quality of the plating, but also reducing the consumption of the plating solution, and more particularly to a central chemical auto control system capable of controlling amounts of the components to be supplied at the centralization place.

Description of the Prior Art

Generally, plating solutions used in the manufacturing process of lead frames or other field are composed of a variety of components. Amounts and concentration ratios of such components considerably influence the quality of products as well as the plating condition. Accordingly, such plating solutions should be controlled in the amounts and concentration ratios of their components within an optimum concentration range. r A.

Meanwhile, the concentrations of basic components in a plating solution may reduce as the reaction time elapses. Conventionally, the reduced concentrations of the basic components have been compensated by manually supplying those components again in certain amounts after a desired time elapses. It is also required to control the plating solution so as to maintain a desired conductivity and pH. To this end, a device for automatically supplying required chemical components has been conventionally used. However, the conventional means for the control of the plating solution requires much labors. In spite of such means, it has also been difficult to maintain the components of the plating solution at optimum conditions in terms of their amounts and concentration ratios. For a plating solution composed of more various elements, in particular, its control becomes more difficult.

SUMMARY OF THE INVENTION

Therefore, the invention has been made in view of the above-mentioned problems involved in the prior art, and an object of the invention is to provide a concentration control apparatus for a plating solution composed of a variety of components, capable of always maintaining the components of the plating solution at optimum conditions in terms of their

2 A & amounts and concentration ratios.

In accordance with the present invention, this object is accomplished by providing an automatic concentration control apparatus for a multicomponent solution supplied by a solution supplying device including a main bath, a number of subsidiary baths arranged in the vicinity of the main bath and contained with undiluted or concentrated solutions of components composing the multi-component solution, respectively, and a number of feeding pumps respectively arranged between the subsidiary baths and the main bath and adapted to quantitatively feed the undiluted or concentrated solutions from the subsidiary baths to the main bath, comprising: a control unit connected, by an interface, to various machines adapted to use the multi-component solution, the control unit being adapted to control the feeding pumps on the basis of the operation conditions of the machines.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and aspects of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings in which:

FIG. 1 is a schematic view illustrating a typical plating solution bath device used in the manufacturing process of lead frames; A_ a 1 FIG. 2 is a block diagram illustrating an apparatus for automatically controlling the concentration of a plating solution in accordance with the present invention, which is applicable to the plating solution bath device shown in FIG. 1; FIG. 3 is a f low chart illustrating the procedure of controlling each f eeding pump by use of the control apparatus of FIG. 2 to achieve a quantitative chemical component supply in accordance with the present invention; FIG. 4 is a flow chart illustrating the procedure of controlling the pumping time of each feeding pump in accordance with the present invention; FIG. 5 is a flow chart illustrating the procedure of controlling each feeding pump to operate in an auto start mode in accordance with the present invention; and FIG. 6 is a flow chart illustrating the procedure of controlling the driving of each feeding pump in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a typical plating solution bath device used in the manufacturing process of lead frames. As shown in FIG. 1, the plating solution bath device includes a main bath MB and a number of subsidiary baths SB arranged in the vicinity of the main bath MB. In the subsidiary baths SB, undiluted or concentrated solutions of components composing a plating solution to be used in the manufacturing process of lead frames are contained, respectively. Between each subsidiary bath SB and the main bath MB, a feeding pump P is arranged to quantitatively feed the concentrated solution from the subsidiary bath SB to the main bath MB.

FIG. 2 illustrates an apparatus for automatically controlling the concentration of a plating solution in accordance with the present invention, which is applicable to the plating solution bath device shown in FIG. 1. As shown in FIG. 2, the concentration control apparatus includes a control unit CU connected, by means of interface devices ID, to various machines M adapted to be used in the manufacturing process of lead frames. The control unit CU is also connected to each feeding pump P SP of the plating solution bath device.

An analog signal, output from each machine M, indicative of the operation condition of lines associated with the machine is received to the control unit CU. The received data is used to calculate the rotating speed and operating time of each feeding pump P in accordance with a given calculation equation, along with data about the baths MB and SB and data about the reaction rate of each associated component of the plating solution (namely, the depletion rate of the component during the operation of the associated lines).

A L on the other hand, FIG. 3 is a flow chart illustrating the procedure of controlling each feeding pump P by use of the control apparatus of FIG. 2 to achieve a quantitative chemical component supply in accordance with the present invention. The control apparatus of the present invention is adapted to operate in either a sampling mode, manual control mode or auto control mode.

In the sampling mode, the control unit CU, which controls the feeding pumps P SP, can take samples from the main bath MB and subsidiary baths SB while performing other functions.

The manual control mode is adapted to provide subsidiary functions for an auto control function. In the manual control mode, each feeding pump P is controlled in accordance with an insufficient or excessive amount of each solution component to maintain the amount of the component in an optimum range. In other words, each component of the solution contained in the main bath MB is analyzed in terms of the concentration and amount during the operation of the automatic plating solution control apparatus. Data indicative of the result of the analysis is received to the control apparatus which, in turn, calculates the RPM and operating time of each feeding pump P, based on the received data. Thus, each f eeding pump P is controlled, based on the results of the calculation. For example, in the case of feeding pumps which feed solution components in excessive amounts, those feeding pumps are kept 6 A & is at their stopped state in an automatic manner for a period corresponding to the surplus amount.

On the other hand, the control unit CU is input with data about the main bath MB and subsidiary bathe, SB, namely, capacities of the baths, desired concentrations of the solution components and data about each feeding pumps P such as the basic RPM and pumping rate. These data are used to calculate the control time and RPM of each feeding pump P when data resulting from the analysis of each component in terms of the concentration and amount is received to the control unit CU.

The control unit W operates considering a plated area, plating time, applied current and potential, and operation status of each machine M, to which a plated area of each machine M is input. The pumping rate varies according to a plated area varied whenever each machine M operates, basically referring to a current placed area already assigned at the time machine M operates.

In the auto control mode, the RPM of each feeding pump P varies in accordance with various parameters such as operation conditions of lead frame production lines and shapes of produced lead frames. In the auto control mode, each component of the plating solution is controlled in accordance with its depletion rate by a continuous adding method or auto start adding method so that its amount can be automatically maintained in an optimum range.

Generally, it is easy to calculate the pumping time and pumping rate of the feeding pumps P if each machine operates without any downtime or under the same condition. However, each machine can not actually operate without downtime or under the same condition.

The auto control mode in accordance with the present invention employs the main bath MB containing various components which is applicable to a number of machines M, thus not only reducing the amount of the plating solution and downtime for setting the baths, but also reducing the labors by accurately adjusting the components in the plating baths.

In the auto control mode, the pumping rate varies in accordance with the plating area of each machine M. The plating area is related to the variation of the number of the machine M.

The pumping rate of the feeding pump is maintained at a fixed rate without any change in the manual control mode or sampling mode.

FIG. 4 is a flow chart illustrating the procedure of controlling the pumping time of each feeding pump in accordance with the present invention. The operating time of each feeding pump is calculated, based on the amount of each associated component to be supplied to the main bath MB. Each feeding pump operates for the calculated operating time and d L then stops automatically.

In accordance with the procedure shown in FIG. 4, the control unit M first reads a timer internally equipped therein and determines whether or not time has elapsed. if time has elapsed, the control unit CU then- checks the operating time of each feeding pump. Where time has not elapsed, the reading operation is repeated.

Thereafter, the number of normally operating lines is checked. Where the number of normally operating lines has varied, the control unit M varies the pumping rate of the feeding pump. If not, the procedure proceeds to the next step for automatically driving the feeding pump.

According to the present invention, each machine M allows various types of products to be plated and has a different operation condition for each product to be plated. During the operation of linest some lines may be under repair or have downtime to substitute the other type of product, by which each line starts to operate at different times.

When the feeding pump has operated for a required operating time, the control unit M checks whether or not the feeding pump rotates reversely, namely, whether or not the feeding pump generates a negative flow. When the feeding pump rotates reversely, the component solution left in a tube adapted to guide the component solution to the main bath is recovered into the associated subsidiary bath.

ld- h After the negative flow is completed, the feeding pump stops. Under this condition, the pumping direction of the feeding pump is changed. The control unit CU then calculates the time for the feeding pump to operate normally again. Thereafter, the feeding pump operates for the calculated operating time.

When there is no negative flow under the condition that the operating time of the feeding pump has elapsed, the feeding pump stops, and the procedure proceeds to the next step to display the operation condition of the feeding pump on a monitor. If the operating time of the feeding pump has not elapsed yet, the amount of the element solution supplied till now is added to the totally accumulated value. Thereafter, the procedure proceeds to the step of displaying the operation condition of the feeding pump. The above procedure is repeated for all feeding pumps. In other words, the number of repeating times corresponds to the number of feeding pumps.

FIG. 5 is a flow chart illustrating the procedure of controlling each feeding pump to operate in an auto start mode. In accordance with the present invention, each feeding motor operates either the sampling mode, manual control mode or auto control mode. The auto control mode includes an auto start mode and a continuous mode. The sampling mode obtains a small amount of solution f rom the main bath as a sample. For this sampling mode, a particular pump with a small - 10 capacity is used.

In the sampling mode, the user obtains a fixed amount of the sample from the main bath MB and subsidiary baths SB by using the feeding pump P operated in the auto control mode and manual control mode, and other pump SP.

In the manual control mode, the user analyzes the concentration of the solution contained in the main bath and determines whether or not the analyzed concentration is lower than a desired concentration. When the analyzed concentration is less than the desired concentration, a concentration difference between these two concentrations is calculated so that the feeding pump can be controlled, based on the calculated concentration difference.

In the manual control mode, the feeding pump is used to feed the concentrated solution of components to the main bath MB from the subsidiary baths SB as in the auto control mode.

In the manual control mode, the feeding pump is used to add a quantitative component either for increasing the concentration of the component or correcting error occurred in the auto control mode.

In the auto control mode, the f eeding pump is used to adjust the component consumed while feeding or stopping the concentrated solution of component supplied to each machine.

The concentration in the main bath is automatically controlled as the operating rate of each component in the main 11 - A AL bath is input to the control unit CU for use only in the auto control mode.

The manual control mode is adapted to provide subsidiary functions for the auto control mode, correcting error occurred in the auto control mode by adding a required amount of the component solution or inputting the analyzed data of the sample to the control unit CU.

In the time-interval control method, each feeding pump is periodically driven for a predetermined time, as shown in FIG. 5. After every driving, the feeding pump stops automatically.

In the continuous control method, each feeding pump is controlled through the on/off manipulation of the user without setting the driving time thereof.

The auto start mode is a time-interval control method, which does not mean the continuous feeding of the component solution but the periodical feeding of the concentrated solution for a fixed time.

The auto start mode is to protect the feeding pump P from the difficult works, namely, feeding a small amount of the solution and reducing the operating time of the pumping.

The continuous mode is to feed the concentrated solution continuously from the subsidiary baths SB, which is useful for adjusting delicately the concentration of each component, but makes the feeding pump overwork. The continuous mode is more accurate than the auto start mode in controlling the plating d L 1 is baths used for the plating line.

In the manual control mode, auto start mode and continuous mode, the same feeding motors are used, as different from the sampling mode. Each feeding pump may be driven in any one of those three modes. However, it is impossible to use any two of those modes at the same time.

FIG. 6 is a flow chart illustrating the procedure of controlling the driving of each feeding pump in accordance with the present invention. Each feeding pump operates for different operating times respectively in different operating modes because it is driven in different manners respectively in those operating modes. Accordingly, the operating time of each feeding pump is calculated using different methods respectively for different operating modes.

For example, in the case of a feeding pump which actually does not have any connection even though it is set, its start is not carried out. Accordingly, it should be determined whether or not the connection of each feeding pump is made, as shown in FIG. 6.

Also, each feeding pump can not operate when setting values include a logically incorrect value disabling the calculation for the pumping time of the feeding pump or when the pumping time is more than 24 hours. Therefore, those conditions should also be checked.

When a feeding pump is desired to generate a negative A- 1 f low, it is controlled to rotate reversely. If not, the feeding pump is normally driven. When the feeding pump, which is in operation, is desired to stop, its control is carried out in accordance with the pumping time controlling procedure shown in FIG. 4.

As mentioned above, the pumping time of each feeding pump is calculated in different methods depending on the operation mode set for the feeding pump.

For example, the pumping time of each feeding pump in the sampling mode is calculated using the following equation:

(Sampte Votume + Deed Votume) X Specific Pumping Rate F tow Rate x Pumping rate Pumping Time = Sample Volume:

Specific Pumping Rate:

Flow Rate Pumping Rate:

Amount (L) of the sample to be taken; Pumping rate (RPM) of the feeding pump as a reference for deriving a flow rate of the solution; Flow rate (L/min) of the solution at a given tube size and specific pumping rate; and Pumping rate (RPM) of the feeding pump to be driven.

j & When the feeding pump is driven to sample the solution contained in the main bath, the solution can not be extracted from the main bath as soon as the feeding pump starts. The solution can be discharged only af ter air existing in the tube is completely vented. This dead volume can be derived using the following equation:

Dead Volume = n()2 x Tube Length Tube Diameter 2 In the manual control mode, the concentration of the solution contained in the main bath is analyzed so that when the analyzed concentration is less than an optimum concentration, a stock solution capable of compensating the shortage of the concentration can be additionally supplied by the pumping operations of desired f eeding pumps. In the manual control mode, the pumping time of each feeding pump can be derived using the following equation:

Pumping Time (Stock Volume + Deed Volume) x Specific Pumping Rate F Low Rate x Pumping Rate The stock volume (L) can be derived using the following equation:

- & a Stock VOLWM (opt i Con. - Analyzed Con.) x Bath city Optimum Con.

Analyzed Con.:

Con. of Stock SOLUtion Con. of Stock Solution:

Desired concentration of the solution (g/L); Analyzed concentration of the solution (g/L); and Concentration of the stock solution (g/L).

In the auto start mode, the user inputs the operation interval of each feeding pump and the operating time of each feeding pump. Based on the input data, each feeding pump operates. On the other hand, each feeding pump operates continuously in the continuous mode unless the user stops the feeding pump. in this case, accordingly, any specific calculation for the pumping time is not required.

As apparent from the above description, the present invention provides a central chemical auto control system for a plating solution, composed of a variety of elements, used in the manufacturing process of lead frames and other fields, capable of always maintaining the components of the plating solution at optimum conditions in terms of their amounts and concentration ratios. In accordance with the present invention, the concentration of each component can be di d automatically and accurately controlled in accordance with the operating line conditions. Accordingly, it is possible to greatly improve the quality of the plating and the quality of products. The consumption of the solution can be greatly reduced.

Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

- 17 A- L

Claims

WHAT IS CLAIMED IS:

1. A concentration control apparatus for a multicomponent solution supplied by a solution supplying device including a main bath, a number of subsidiary baths arranged in the vicinity of the main bath and contained with undiluted or concentrated solutions of components composing the multicomponent solution, respectively, and a number of feeding pumps respectively arranged between the subsidiary baths and the main bath and adapted to quantitatively feed the undiluted or concentrated solutions from the subsidiary baths to the main bath, comprising:

a control unit connected, by an interface, to various machines adapted to use the multi-component solution, the control unit being adapted to control the feeding pumps on the basis of operation conditions of the machines and operating considering a plated area, plating time, applied current and potential, and operation status of each machine M.

2. The concentration control apparatus in accordance with claim 1, wherein the feeding pumps are adapted to operate in either a sampling mode, manual control mode or auto control mode.

3. The concentration control apparatus in accordance with - 18 1 claim 1, wherein the control unit is stored with data about capacities of the main bath and subsidiary baths, data about optimum concentrations of the components composing the multicomponent solution, and data about the feeding pumps so that the data can be used to calculate required pumping times and RPMs of the feeding pumps when the control unit receives data about the operation conditions from the machines.

4. A concentration control apparatus substantially as described herein with reference to and as shown in the drawings.

5. Any novel feature described herein and any novel combination of herein described features.

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